A pseudocapacitance dominated anode material assembled from Li_(3)VO_(4)nanocrystals encapsulated in the interlayers of N-doped graphene has been developed via a facile 2D nanospace confined strategy for lithium ion c...A pseudocapacitance dominated anode material assembled from Li_(3)VO_(4)nanocrystals encapsulated in the interlayers of N-doped graphene has been developed via a facile 2D nanospace confined strategy for lithium ion capacitors(LICs).In this contribution,the N-doped graphene synthesized by a faicle solid state reaction using C_(3)N_(4)nanosheets as template and glucose as carbon source provides sufficient 2D nanospace for the confined and homogeneous growth of Li_(3)VO_(4)at the nanoscale,and simultaneously efficiently anchors each nanobuilding block inside the interlayers,thus realizing the utilizaiton of full potential of active components.The so-formed 3D hybrids not only ensure intimate electronic coupling between active materials and N-doped graphene,but also realize robust structure integrity.Owing to these unique advantages,the resulting hybrids show pseudocapacitance dominated lithium storage behaviors with capacitive contributions of over 90%at both low and high current rates.The LVO@C@NG delivers reversible capacities of 206 mAh/g at 10 A/g,capacity retention of 92.7%after 1000 cycles at 2 A/g,and a high energy density of 113.6 Wh/kg at 231.8 W/kg for LICs.展开更多
High-performance and low-cost sodium-ion capacitors(SICs)show tremendous potential applications in public transport and grid energy storage.However,conventional SICs are limited by the low specific capacity,poor rate ...High-performance and low-cost sodium-ion capacitors(SICs)show tremendous potential applications in public transport and grid energy storage.However,conventional SICs are limited by the low specific capacity,poor rate capability,and low initial coulombic efficiency(ICE)of anode materials.Herein,we report layered iron vanadate(Fe5V15O39(OH)9·9H2O)ultrathin nanosheets with a thickness of~2.2 nm(FeVO UNSs)as a novel anode for rapid and reversible sodium-ion storage.According to in situ synchrotron X-ray diffractions and electrochemical analysis,the storage mechanism of FeVO UNSs anode is Na+intercalation pseudocapacitance under a safe potential window.The FeVO UNSs anode delivers high ICE(93.86%),high reversible capacity(292 mAh g^−1),excellent cycling stability,and remarkable rate capability.Furthermore,a pseudocapacitor–battery hybrid SIC(PBH-SIC)consisting of pseudocapacitor-type FeVO UNSs anode and battery-type Na3(VO)2(PO4)2F cathode is assembled with the elimination of presodiation treatments.The PBH-SIC involves faradaic reaction on both cathode and anode materials,delivering a high energy density of 126 Wh kg^−1 at 91 W kg^−1,a high power density of 7.6 kW kg^−1 with an energy density of 43 Wh kg−1,and 9000 stable cycles.The tunable vanadate materials with high-performance Na+intercalation pseudocapacitance provide a direction for developing next-generation highenergy capacitors.展开更多
Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials ...Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.展开更多
Cobalt-Aluminum layered double hydroxide(CoAl LDH) is a hopeful electrode material due to the advantage of easy modifiability for preparing LDH-based derivatives.However,there is short of modification methods to prepa...Cobalt-Aluminum layered double hydroxide(CoAl LDH) is a hopeful electrode material due to the advantage of easy modifiability for preparing LDH-based derivatives.However,there is short of modification methods to prepare the Co-based derivatives from CoAl LDH and also short of an intuitive perspective to analyze the pseudocapacitance mechanism of CoAl LDH and its derivatives.Herein,Graphene/CoAl LDH and its derivatives including Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP were prepared by reasonably using alkali etching treatment,sulfofication and phosphorization.The specific capacitance of Graphene/CoAl LDH,Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP at1 A g^(-1) are 260.7,371.3,440.8,61.4 and 122.2 F g^(-1),especially.The pseudocapacitance mechanism of Graphene/CoAl LDH and its derivatives was analyzed.Due to the positive effect of sulfofication on the electrical conductivity of GO and cobalt sulfide,the Graphene/CoS and Graphene/CoS-1 exhibit the optimal electrochemical performance and superior rate capability.In addition,due to the repulsion effect between Graphene and OH-,the Graphene/CoAl LDH exhibits optimal cycling stability of 224.1% capacitance retention after 20000 cycles.Besides,the reason of terrible specific capacitance of Graphene/CoOOH is that the presence of H bond in interlayer of CoOOH inhibits the interaction between Co3+ and OHspecies.Hence,not all modifications will increase the specific capacitance of the electrode materials.Overall,this work provides us with a detailed analysis of the electrochemical mechanism and correlation of CoAl LDH and its derivatives from the perspective of crystal structure and composition.展开更多
It is challenging to create cation vacancies in electrode materials for enhancing the performance of rechargeable lithium ion batteries (LIBs). Herein, we utilized a strong alkaline etching method to successfully crea...It is challenging to create cation vacancies in electrode materials for enhancing the performance of rechargeable lithium ion batteries (LIBs). Herein, we utilized a strong alkaline etching method to successfully create Co vacancies at the interface of atomically thin Co_(3−x)O_(4)/graphene@CNT heterostructure for high-energy/power lithium storage. The creation of Co-vacancies in the sample was confirmed by high-resolution scanning transmission electron microscope (HRSTEM), X-ray photoelectron spectroscopy (XPS) and electron energy loss near-edge structures (ELNES). The obtained Co_(3−x)O_(4)/graphene@CNT delivers an ultra-high capacity of 1688.2 mAh g^(−1) at 0.2 C, excellent rate capability of 83.7% capacity retention at 1 C, and an ultralong life up to 1500 cycles with a reversible capacity of 1066.3 mAh g^(−1). Reaction kinetic study suggests a significant contribution from pseudocapacitive storage induced by the Co-vacancies at the Co_(3−x)O_(4)/graphene@CNT interface. Density functional theory confirms that the Co-vacancies could dramatically enhance the Li adsorption and provide an additional pathway with a lower energy barrier for Li diffusion, which results in an intercalation pseudocapacitive behavior and high-capacity/rate energy storage.展开更多
Energy density can be substantially raised and even maximized if the bulk of an electrode material is fully utilized.Transition metal oxides based on conversion reaction mechanism are the imperative choice due to eith...Energy density can be substantially raised and even maximized if the bulk of an electrode material is fully utilized.Transition metal oxides based on conversion reaction mechanism are the imperative choice due to either constructing nanostructure or intercalation pseudocapacitance with their intrinsic limitations.However,the fully bulk utilization of transition metal oxides is hindered by the poor understanding of atomic-level conversion reaction mechanism,particularly it is largely missing at clarifying how the phase transformation(conversion reaction)determines the electrochemical performance such as power density and cyclic stability.Herein,α-Fe_(2)O_(3) is a case provided to claim how the diffusional and diffusionless transformation determine the electrochemical behaviors,as of its conversion reaction mechanism with fully bulk utilization in alkaline electrolyte.Specifically,the discharge productα-FeOOH diffusional from Fe(OH)2 is structurally identified as the atomic-level arch criminal for its cyclic stability deterioration,whereas the counterpartδ-FeOOH is theoretically diffusionless-like,unlocking the full potential of the pseudocapacitance with fully bulk utilization.Thus,such pseudocapacitance,in proof-of-concept and termed as conversion pseudocapacitance,is achieved via diffusionless-like transformation.This work not only provides an atomic-level perspective to reassess the potential electrochemical performance of the transition metal oxides electrode materials based on conversion reaction mechanism but also debuts a new paradigm for pseudocapacitance.展开更多
Manganese phosphates have shown excellent performances and great potential in electrochemical energy storage,which are demonstrated by research works published in recent years.For manganese phosphates,the open-framewo...Manganese phosphates have shown excellent performances and great potential in electrochemical energy storage,which are demonstrated by research works published in recent years.For manganese phosphates,the open-framework structures with large channels and cavities endow them with good ion conductivity and charge storage capacity.In this review,we present the recent progress on manganese phosphates,by focusing on their advantages/disadvantages and potential applications as a new class of electrode materials in supercapacitors.The structural characteristics,synthesis methods,and mineral sources to prepare these manganese phosphates are investigated,together with the modification,as they strongly affect the electrochemical energy storage performance.Attentions are paid to those hybrid-type materials,where strong synergistic effects exist.In the summary,interlayer engineering for the manganese phosphates and hybrid-types are proposed and discussed.展开更多
Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheles...Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheless,applications of SICs are severely restricted by their insufficient energy densities (<100Wh/kg) resulted from the kinetics imbalance between cathodes and anodes.Herein,we report a nanograin-boundary-rich hierarchical Co_(3)O_(4) nanorod anode composed of~20 nm nanocrystallites.Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na^(+) storage process.Co_(3)O_(4) nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g),excellent rate capability (335 mAh/g@5.0 A/g),and improved cycle stability (100 cycles@1.0 A/g with negligible capacity degradation).The outstanding performance can be credited to the hierarchical morphology of Co_(3)O_(4) nanorods and the well-designed nanograinboundaries between nanocrystallites that avoid particle agglomeration,induce pseudocapacitive-type Na^(+) storage,and accommodate volume variation during sodiation-desodiation processes.Nitrogendoping of the Co_(3)O_(4) nanorods not only generates defects for extra surficial Na^(+) storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na^(+) intercalation.Synergy of conventional reaction mechanism and pseudocapacitive-type Na^(+) storage enables high specific capacity,rapid Na^(+) diffusion,and improved structural stability of the Co_(3)O_(4) nanorod electrode.The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg),power density (6632 W/kg@37 Wh/kg),cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%),and coulombic efficiency (~100%).展开更多
Layered nickel oxides have been focused with intense research interests as high-performance lithium-ion batterie(LIB)anode.However,it is hard to obtain few layered nickel oxides material directly as it easily forms bu...Layered nickel oxides have been focused with intense research interests as high-performance lithium-ion batterie(LIB)anode.However,it is hard to obtain few layered nickel oxides material directly as it easily forms bulk material with the strong interaction between the interlayer.In this work,two-dimensional(2 D)nickel-based coordination polymers were successfully prepared according to aqueous phase copolymerization approach.And then uniform carbondoped NiO nanosheets were successfully obtained from facile solution assembly and post-thermal treatment.The detailed electrochemical testing shows that the uniform NiO nanocrystals encapsulated into porous N-doped carbon(NiO@NC)nanosheets present much higher rate capability with the discharge specific capacity of 782.7 mAh·g^(-1) at high current density of 2.0 A·g^(-1) than pure NiO(690 mAh·g^(-1)).It also shows long-term cycling performance with 91%retention after 50 cycles at 1.0 A·g^(-1).The high rate capability,cycling stability and the easy synthesis make NiO@NC nanosheets as a promising candidate for LIB anode and build up new way for the fabrication of metal oxides anode materials.展开更多
Pseudocapacitive materials that store charges via reversible surface or near-surface faradaic reactions are capable of overcoming the capacity limitations of electrical double-layer capacitors.Revealing the structure...Pseudocapacitive materials that store charges via reversible surface or near-surface faradaic reactions are capable of overcoming the capacity limitations of electrical double-layer capacitors.Revealing the structure–activity relationship between the microstructural features of pseudocapacitive materials and their electrochemical performance on the atomic scale is the key to build high-performance capacitor-type devices containing ideal pseudocapacitance effect.Currently,the high brightness(flux),and spectral and coherent nature of synchrotron X-ray analytical techniques make it a powerful tool for probing the structure–property relationship of pseudocapacitive materials.Herein,we report a comprehensive and systematic review of four typical characterization techniques(synchrotron X-ray diffraction,pair distribution function[PDF]analysis,soft X-ray absorption spectroscopy,and hard X-ray absorption spectroscopy)for the study of pseudocapacitance mechanisms.In addition,we offered significant insights for understanding and identifying pseudocapacitance mechanisms(surface redox pseudocapacitance,intercalation pseudocapacitance,and the extrinsic pseudocapacitance phenomenon in battery materials)by combining in situ hard XAS and electrochemical analyses.Finally,a perspective for further depth of understanding into the pseudocapacitance mechanism using synchrotron X-ray analytical techniques is proposed.展开更多
The design and development of energy storage device with high energy/power density has become a research hotspot.Zinc-ion hybrid capacitors(ZHCs)are considered as one of the most promising candidates.However,the appli...The design and development of energy storage device with high energy/power density has become a research hotspot.Zinc-ion hybrid capacitors(ZHCs)are considered as one of the most promising candidates.However,the application of ZHCs is hindered by their low energy density at high power density due to the unsatisfactory cathode material.In this study,a novel 3D phosphorus-doped carbon nanotube/reduced graphene oxide(P-CNT/rGO)aerogel cathode is synthesized through a synergistic modification strategy of CNT insertion and P doping modification combined with 3D porous design.The as-obtained P-CNT/rGO aerogel cathode manifests significantly increased surface aera,expanded interlayer spacing,and enhanced pseudocapacitance behavior,thus leading to significantly enhanced specific capacitance and superb ions transport performance.The as-assembled ZHC based on P-CNT/rGO cathode delivers a superior energy density of 42.2 Wh/kg at an extreme-high power density of 80 kW/kg and excellent cycle life.In-depth kinetic analyses are undertaken to prove the enhanced pseudocapacitance behavior and exceptional power output capability of ZHCs.Furthermore,the reaction mechanism of physical and chemical adsorption/desorption of electrolyte ions on the P-CNT/rGO cathode is revealed by systematic ex-situ characterizations.This work can provide a valuable reference for developing advanced graphene-based cathode for high energy/power density ZHCs.展开更多
Drinking water contamination by heavy metals,particularly chromium and arsenic oxyanions,is a severe challenge threatening humanity’s sustainable development.Electrochemically mediated water purification is gaining a...Drinking water contamination by heavy metals,particularly chromium and arsenic oxyanions,is a severe challenge threatening humanity’s sustainable development.Electrochemically mediated water purification is gaining attention due to its high uptake,rapid kinetics,modularity,and facile regeneration.Here,we designed a composite electrode by combining a redox-active/Faradaic polymer,poly(norbornene-diphenothiazine)(PNP_(2)),with carbon nanotubes(CNTs)–PNP_(2)-CNT.The PNP_(2)-CNT demonstrated exceptional pseudocapacitance behavior,resulting in significantly accelerated adsorption rates for dichromate(Cr(Ⅵ);0.008 gmg^(-1) min^(-1))and arsenite(As(Ⅲ);0.03 gmg^(-1) min^(-1)),surpassing reported materials by a margin of 3–200 times,while demonstrating a high adsorption capacity,666.3 and 612.4 mg g^(-1),respectively.Furthermore,it effectively converted As(Ⅲ)to the less toxic arsenate(As(Ⅴ))during adsorption and Cr(Ⅵ)to the less toxic chromium(Cr(Ⅲ))during desorption.This PNP_(2)-CNT system also showed significantly lower energy consumption,only 0.17%of the CNT control system.This study demonstrated for the first time the use of PNP_(2) redox-active polymers in the separation and conversion process,meeting the six criteria of high uptake,rapid kinetics,selectivity,stability,recyclability,and energy efficiency.This achievement expands the scope of advanced materials that address environmental concerns and make an impact by generating energy-and cost-effective water purification.展开更多
Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline el...Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.展开更多
Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-ty...Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-type mechanism for Na+storage in VN anodes but does not explain the phenomena of their size-dependent specific capacities and underlying causes of pseudocapacitive charge storage behaviors.Herein,we insightfully reveal the VN anode exhibits a surface-redox pseudocapacitive mechanism in nonaqueous,Na+-based electrolytes,as demonstrated by kinetics analysis,experimental observations,and first-principles calculations.Through ex situ X-ray photoelectron spectroscopy and semiquantitative analyses,the Na+storage is characterized by redox reactions occurring with the V5+/V4+to V3+at the surface of VN particles,which is different from the well-known conversion reaction mechanism.The pseudocapacitive performance is enhanced through nanoarchitecture design via oxidized vanadium states at the surface.The optimized VN-10 nm anode delivers a sodium-ion storage capability of 106 mAh g−1 at the high specific current of 20 A g−1,and excellent cycling performance of 5000 cycles with negligible capacity losses.This work demonstrates the emerging opportunities of utilizing pseudocapacitive charge storage for realizing high-rate sodium-ion storage applications.展开更多
Potassium-ion batteries(PIBs)are promising ne15t-generation energy storage candidates due to abundant resources and low cost.Sb-based materials with high theoretical capacity(660 mAh·g^(-1))and low working potent...Potassium-ion batteries(PIBs)are promising ne15t-generation energy storage candidates due to abundant resources and low cost.Sb-based materials with high theoretical capacity(660 mAh·g^(-1))and low working potential are considered as promising anode for PIBs.The remaining challenge is poor stability and slow kinetics.In this work,FeSb@N-doped carbon quantum dots anchored in three-dimensional(3D)porous N-doped carbon(FeSb@C/Nc3DC/N),a Sb-based material with a particular structure,is designed and constructed by a green salt-template method.As an anode for PIBs,it exhibits extraordinarily high-rate and long-cycle stability(a capacity of 245 mAh·g^(-1) at 3,080 mAh·g^(-1) after 1,000 cycles).The pseudocapacitance contribution(83%)is demonstrated as the origin of high-rate performance of the FeSb@C/NС3DC/N electrode.Furthermore,the potassium storage mechanism in the electrode is systematically investigated through ex-situ characterization techniques including ex-situ transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).Overall,this study could provide a useful guidance for future design of high-performance electrode materials for PIBs.展开更多
Compressible supercapacitors play an increasingly significant role in flexible sensors and wearable electronic devices.However,the integration of mechanical compressibility and excellent electrochemical performance in...Compressible supercapacitors play an increasingly significant role in flexible sensors and wearable electronic devices.However,the integration of mechanical compressibility and excellent electrochemical performance into a single device remains a challenge.Herein,we demonstrate a compressible and high-performance supercapacitor based on an N-doped carbon foam elastomer with hierarchical carbon nanotubes.Hierarchically structured Fe3C@N-doped carbon nanotubes/N-doped carbon foam and Ni@N-doped carbon nanotubes/N-doped carbon foam have been synthesized via a simple and universal self-catalytic strategy.The hierarchical structural features of self-catalytic N-doped carbon nanotubes serve as a cushion when the composite is subjected to an external force,exhibiting excellent mechanical properties with a maximum compressive strain of 80%and fatigue resistance of 1000 cycles.Moreover,the different electroactive potentials of the transition-metal species in the composites provide the assembly with a maximum operating voltage of 1.4 V,which shows a maximum energy density of∼10.74 Wh kg^(−1)(0.084 mWh cm^(−3))at the power density of∼179.2 W kg^(−1)(1.4 mWh cm^(−3)),and retains 88.4%of the original capacitance after 20,000 charge–discharge cycles,even at a strain of 80%.This work paves the way for controllable fabrication of compressible electrodes and supercapacitors.展开更多
Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This wo...Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This work presents an innovative Pseudocapacitive Sensor.The key lies in switching the energy storage kinetics from pseudocapacitor to electrical double layer capacitor by employing the change of local pH(-log[H^(+)])in MXene-based flexible supercapacitors during bending.Pseudocapacitive sensing is observed in acidic electrolyte but absent in neutral electrolyte.Applied shearing during bending causes liquid-crystalline MXene sheets to increase in their degree of anisotropic alignment.With blocking of H+mobility due to the higher diffusion barrier,local pH increases.The electrochemical energy storage kinetics transits from Faradaic chemical protonation(intercalation)to non-Faradaic physical adsorption.We utilize the phenomenon of capacitance change due to shifting energy storage kinetics for strain sensing purposes.The developed highly sensitive Pseudocapacitive Sensors feature a remarkable gauge factor(GF)of approximately 1200,far surpassing conventional strain sensors(GF:~1 for dielectric-cap sensor).The introduction of the Pseudocapacitive Sensor represents a paradigm shift,expanding the application of pseudocapacitance from being solely confined to energy devices to the realm of multifunctional electronics.This technological leap enriches our understanding of the pseudocapacitance mechanism of MXenes,and will drive innovation in cutting-edge technology areas,including advanced robotics,implantable biomedical devices,and health monitoring systems.展开更多
Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact an...Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.展开更多
The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel...The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel lithium titanate(LTO)is a strong contender to replace graphite anodes due to its optimal zero-strain merit and outstanding structural stability.Nevertheless,low reversible capacity and poor rate performance hinder the widespread application of LTO.Amazingly,the promising pseudocapacitive effect enables LTO to surmount the limit of theoretical capacity via boosted surface Li storage,contributing to observably upgraded energy and power densities in a wide temperature range.By leveraging the synergistic effect of multiple modification strategies to create additional active sites,the pseudocapacitive response of LTO can be markedly enhanced.This paper reviews the progress of pseudocapacitive LTO for the first time.We highlight the zero-strain characteristic and pseudocapacitance mechanism of LTO and review the design strategies of pseudocapacitive LTO.Significative issues for further developing pseudocapacitive LTO are proposed.It is worth noting that the pseudocapacitive contribution can greatly improve the low-temperature electrochemical performances of LTO.We anticipate that more efforts will be aroused to study the advanced pseudocapacitive LTO to accelerate the development of next-generation LIBs and energy storage devices.展开更多
SnO_(2)is a potential anode material with high theoretical capacity for lithium-ion batteries(LIBs),however,its applications have been limited by the severe volume expansion during charging-discharging process.In this...SnO_(2)is a potential anode material with high theoretical capacity for lithium-ion batteries(LIBs),however,its applications have been limited by the severe volume expansion during charging-discharging process.In this work,an inverse opal TiO_(2)/SnO_(2)composite with an interconnect network nanostructure was designed to confine Sn O_(2)nanoparticles in the porous TiO_(2).Due to this nanoconfinement structure,the volume expansion in the process was effectively alleviated,therefore the safety performance and cycling stability of the battery were effectively improved.At the same time,with a large number of microporous structures in the framework,the appearance of pseudocapacitance improves the rate performance and reversible capacity.In terms of electrochemical kinetics,its framework provides the connected path for charge migration,effectively reducing the charge transfer impedance,meanwhile,quantities of micropores in its skeleton could provide a smoother channel for lithium ions,thus greatly improving the diffusion rate of LIBs.The design of this nanostructure provides a new idea for the research of SnO_(2)-based anode with effectively enhanced electrochemical performance,which is promising anode for practical application.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52001059,52072119)Hunan Provincial Natural Science Foundation(No.2023JJ50015)the 111 Project(No.D20015)。
文摘A pseudocapacitance dominated anode material assembled from Li_(3)VO_(4)nanocrystals encapsulated in the interlayers of N-doped graphene has been developed via a facile 2D nanospace confined strategy for lithium ion capacitors(LICs).In this contribution,the N-doped graphene synthesized by a faicle solid state reaction using C_(3)N_(4)nanosheets as template and glucose as carbon source provides sufficient 2D nanospace for the confined and homogeneous growth of Li_(3)VO_(4)at the nanoscale,and simultaneously efficiently anchors each nanobuilding block inside the interlayers,thus realizing the utilizaiton of full potential of active components.The so-formed 3D hybrids not only ensure intimate electronic coupling between active materials and N-doped graphene,but also realize robust structure integrity.Owing to these unique advantages,the resulting hybrids show pseudocapacitance dominated lithium storage behaviors with capacitive contributions of over 90%at both low and high current rates.The LVO@C@NG delivers reversible capacities of 206 mAh/g at 10 A/g,capacity retention of 92.7%after 1000 cycles at 2 A/g,and a high energy density of 113.6 Wh/kg at 231.8 W/kg for LICs.
基金This work was financially supported by the National Natural Science Foundation of China(No.22005256)the National Key R&D Program of China(Grant No.2016YFA0202600)the Natural Science Foundation of Fujian Province of China(No.2020J01034).
文摘High-performance and low-cost sodium-ion capacitors(SICs)show tremendous potential applications in public transport and grid energy storage.However,conventional SICs are limited by the low specific capacity,poor rate capability,and low initial coulombic efficiency(ICE)of anode materials.Herein,we report layered iron vanadate(Fe5V15O39(OH)9·9H2O)ultrathin nanosheets with a thickness of~2.2 nm(FeVO UNSs)as a novel anode for rapid and reversible sodium-ion storage.According to in situ synchrotron X-ray diffractions and electrochemical analysis,the storage mechanism of FeVO UNSs anode is Na+intercalation pseudocapacitance under a safe potential window.The FeVO UNSs anode delivers high ICE(93.86%),high reversible capacity(292 mAh g^−1),excellent cycling stability,and remarkable rate capability.Furthermore,a pseudocapacitor–battery hybrid SIC(PBH-SIC)consisting of pseudocapacitor-type FeVO UNSs anode and battery-type Na3(VO)2(PO4)2F cathode is assembled with the elimination of presodiation treatments.The PBH-SIC involves faradaic reaction on both cathode and anode materials,delivering a high energy density of 126 Wh kg^−1 at 91 W kg^−1,a high power density of 7.6 kW kg^−1 with an energy density of 43 Wh kg−1,and 9000 stable cycles.The tunable vanadate materials with high-performance Na+intercalation pseudocapacitance provide a direction for developing next-generation highenergy capacitors.
基金supported by the National Natural Science Foundation of China(51832004,51521001)the National Key Research and Development Program of China(2016YFA0202603)+2 种基金the Program of Introducing Talents of Discipline to Universities(B17034)the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)the “Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University。
文摘Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.
基金the financial support provided by the Graduate Research and innovation of Chongqing, China (Grant No. CYB18002)the National Natural Science Foundation of China (Grant No. 21576034 and 51908092)+1 种基金the State Education Ministry and Fundamental Research Funds for the Central Universities (2019CDQYCL042, 2019CDXYCL0031, 106112017CDJXSYY0001, 2018CDYJSY0055, 106112017CDJQJ138802, 106112017CDJSK04XK11, and 2018CDQYCL0027)the Joint Funds of the National Natural Science Foundation of China-Guangdong (Grant No. U1801254)。
文摘Cobalt-Aluminum layered double hydroxide(CoAl LDH) is a hopeful electrode material due to the advantage of easy modifiability for preparing LDH-based derivatives.However,there is short of modification methods to prepare the Co-based derivatives from CoAl LDH and also short of an intuitive perspective to analyze the pseudocapacitance mechanism of CoAl LDH and its derivatives.Herein,Graphene/CoAl LDH and its derivatives including Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP were prepared by reasonably using alkali etching treatment,sulfofication and phosphorization.The specific capacitance of Graphene/CoAl LDH,Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP at1 A g^(-1) are 260.7,371.3,440.8,61.4 and 122.2 F g^(-1),especially.The pseudocapacitance mechanism of Graphene/CoAl LDH and its derivatives was analyzed.Due to the positive effect of sulfofication on the electrical conductivity of GO and cobalt sulfide,the Graphene/CoS and Graphene/CoS-1 exhibit the optimal electrochemical performance and superior rate capability.In addition,due to the repulsion effect between Graphene and OH-,the Graphene/CoAl LDH exhibits optimal cycling stability of 224.1% capacitance retention after 20000 cycles.Besides,the reason of terrible specific capacitance of Graphene/CoOOH is that the presence of H bond in interlayer of CoOOH inhibits the interaction between Co3+ and OHspecies.Hence,not all modifications will increase the specific capacitance of the electrode materials.Overall,this work provides us with a detailed analysis of the electrochemical mechanism and correlation of CoAl LDH and its derivatives from the perspective of crystal structure and composition.
基金This work was financially supported by the Australian Research Council(ARC)Discovery Projects(DP210103266,DP200100965 and DP200100365)the ARC Discovery Early Career Researcher Award(DE210101102)the Griffith University Postdoctoral Fellowship Scheme(YUDOU 036 Research Internal).
文摘It is challenging to create cation vacancies in electrode materials for enhancing the performance of rechargeable lithium ion batteries (LIBs). Herein, we utilized a strong alkaline etching method to successfully create Co vacancies at the interface of atomically thin Co_(3−x)O_(4)/graphene@CNT heterostructure for high-energy/power lithium storage. The creation of Co-vacancies in the sample was confirmed by high-resolution scanning transmission electron microscope (HRSTEM), X-ray photoelectron spectroscopy (XPS) and electron energy loss near-edge structures (ELNES). The obtained Co_(3−x)O_(4)/graphene@CNT delivers an ultra-high capacity of 1688.2 mAh g^(−1) at 0.2 C, excellent rate capability of 83.7% capacity retention at 1 C, and an ultralong life up to 1500 cycles with a reversible capacity of 1066.3 mAh g^(−1). Reaction kinetic study suggests a significant contribution from pseudocapacitive storage induced by the Co-vacancies at the Co_(3−x)O_(4)/graphene@CNT interface. Density functional theory confirms that the Co-vacancies could dramatically enhance the Li adsorption and provide an additional pathway with a lower energy barrier for Li diffusion, which results in an intercalation pseudocapacitive behavior and high-capacity/rate energy storage.
基金This research is supported by the National Natural Science Foundation of China (51932003,51872115)2020 International Cooperation Project of the Department of Science and Technology of Jilin Province (20200801001GH)+5 种基金Program for the Development of Science and Technology of Jilin Province (20190201309JC)the Jilin Province/Jilin University Co-Construction Project-Funds for New Materials (SXGJSF2017-3,Branch-2/440050316A36)Project for Self-innovation Capability Construction of Jilin Province Development and Reform Commission (2021C026)the Open Project Program of Wuhan National Laboratory for Optoelectronics (2018WNLOKF022)the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT,2017TD-09)the Fundamental Research Funds for the Central Universities JLU,and“Double-First Class”Discipline for Materials Science&Engineering.
文摘Energy density can be substantially raised and even maximized if the bulk of an electrode material is fully utilized.Transition metal oxides based on conversion reaction mechanism are the imperative choice due to either constructing nanostructure or intercalation pseudocapacitance with their intrinsic limitations.However,the fully bulk utilization of transition metal oxides is hindered by the poor understanding of atomic-level conversion reaction mechanism,particularly it is largely missing at clarifying how the phase transformation(conversion reaction)determines the electrochemical performance such as power density and cyclic stability.Herein,α-Fe_(2)O_(3) is a case provided to claim how the diffusional and diffusionless transformation determine the electrochemical behaviors,as of its conversion reaction mechanism with fully bulk utilization in alkaline electrolyte.Specifically,the discharge productα-FeOOH diffusional from Fe(OH)2 is structurally identified as the atomic-level arch criminal for its cyclic stability deterioration,whereas the counterpartδ-FeOOH is theoretically diffusionless-like,unlocking the full potential of the pseudocapacitance with fully bulk utilization.Thus,such pseudocapacitance,in proof-of-concept and termed as conversion pseudocapacitance,is achieved via diffusionless-like transformation.This work not only provides an atomic-level perspective to reassess the potential electrochemical performance of the transition metal oxides electrode materials based on conversion reaction mechanism but also debuts a new paradigm for pseudocapacitance.
基金financially supported by the Sichuan Science and Technology Project(No.2020YJ0163)the Research Foundation for Teacher Development of Chengdu University of Technology(No.10912-2019KYQD-06847)the Science and Technology Innovation Foundation for University Students(No.30800-2019DCXM065)。
文摘Manganese phosphates have shown excellent performances and great potential in electrochemical energy storage,which are demonstrated by research works published in recent years.For manganese phosphates,the open-framework structures with large channels and cavities endow them with good ion conductivity and charge storage capacity.In this review,we present the recent progress on manganese phosphates,by focusing on their advantages/disadvantages and potential applications as a new class of electrode materials in supercapacitors.The structural characteristics,synthesis methods,and mineral sources to prepare these manganese phosphates are investigated,together with the modification,as they strongly affect the electrochemical energy storage performance.Attentions are paid to those hybrid-type materials,where strong synergistic effects exist.In the summary,interlayer engineering for the manganese phosphates and hybrid-types are proposed and discussed.
基金financially supported by the IMDEA Materials Institute STRUBAT Project, Spanish Ministry of Economy, Industry, and Competitiveness (MINECO), the Spanish Ministry of Science and Innovation, and Comunidad de Madrid for Juan de la Cierva fellowship (IJCI-2015-25488)the Retos Investigacion Project (MAT2017-84002-C2-2-R)/Ramon y Cajal fellowship (RYC-2018-025893-I)+1 种基金the Talent attraction fellowship (2016-T1/IND-1300)the China Scholarship Council (201706740087)。
文摘Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheless,applications of SICs are severely restricted by their insufficient energy densities (<100Wh/kg) resulted from the kinetics imbalance between cathodes and anodes.Herein,we report a nanograin-boundary-rich hierarchical Co_(3)O_(4) nanorod anode composed of~20 nm nanocrystallites.Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na^(+) storage process.Co_(3)O_(4) nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g),excellent rate capability (335 mAh/g@5.0 A/g),and improved cycle stability (100 cycles@1.0 A/g with negligible capacity degradation).The outstanding performance can be credited to the hierarchical morphology of Co_(3)O_(4) nanorods and the well-designed nanograinboundaries between nanocrystallites that avoid particle agglomeration,induce pseudocapacitive-type Na^(+) storage,and accommodate volume variation during sodiation-desodiation processes.Nitrogendoping of the Co_(3)O_(4) nanorods not only generates defects for extra surficial Na^(+) storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na^(+) intercalation.Synergy of conventional reaction mechanism and pseudocapacitive-type Na^(+) storage enables high specific capacity,rapid Na^(+) diffusion,and improved structural stability of the Co_(3)O_(4) nanorod electrode.The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg),power density (6632 W/kg@37 Wh/kg),cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%),and coulombic efficiency (~100%).
基金financially supported by the National Natural Science Foundation of China(No.21676060)the Natural Science Foundation of Guangdong Province of China(No.2018A030313516)the Science and Technology Planning Project of Guangzhou(No.201804010449)。
文摘Layered nickel oxides have been focused with intense research interests as high-performance lithium-ion batterie(LIB)anode.However,it is hard to obtain few layered nickel oxides material directly as it easily forms bulk material with the strong interaction between the interlayer.In this work,two-dimensional(2 D)nickel-based coordination polymers were successfully prepared according to aqueous phase copolymerization approach.And then uniform carbondoped NiO nanosheets were successfully obtained from facile solution assembly and post-thermal treatment.The detailed electrochemical testing shows that the uniform NiO nanocrystals encapsulated into porous N-doped carbon(NiO@NC)nanosheets present much higher rate capability with the discharge specific capacity of 782.7 mAh·g^(-1) at high current density of 2.0 A·g^(-1) than pure NiO(690 mAh·g^(-1)).It also shows long-term cycling performance with 91%retention after 50 cycles at 1.0 A·g^(-1).The high rate capability,cycling stability and the easy synthesis make NiO@NC nanosheets as a promising candidate for LIB anode and build up new way for the fabrication of metal oxides anode materials.
基金financialy supported by National Key R&D Program of China(2022YFB2402600)the National Natural Science Foundation of China(22279166)+1 种基金the Research Start-up Funds from Sun Yat-Sen University(200306)the Fundamental Research Funds for the Central Universities,Sun Yat-Sen University(22qntd0101 and 22dfx01)
文摘Pseudocapacitive materials that store charges via reversible surface or near-surface faradaic reactions are capable of overcoming the capacity limitations of electrical double-layer capacitors.Revealing the structure–activity relationship between the microstructural features of pseudocapacitive materials and their electrochemical performance on the atomic scale is the key to build high-performance capacitor-type devices containing ideal pseudocapacitance effect.Currently,the high brightness(flux),and spectral and coherent nature of synchrotron X-ray analytical techniques make it a powerful tool for probing the structure–property relationship of pseudocapacitive materials.Herein,we report a comprehensive and systematic review of four typical characterization techniques(synchrotron X-ray diffraction,pair distribution function[PDF]analysis,soft X-ray absorption spectroscopy,and hard X-ray absorption spectroscopy)for the study of pseudocapacitance mechanisms.In addition,we offered significant insights for understanding and identifying pseudocapacitance mechanisms(surface redox pseudocapacitance,intercalation pseudocapacitance,and the extrinsic pseudocapacitance phenomenon in battery materials)by combining in situ hard XAS and electrochemical analyses.Finally,a perspective for further depth of understanding into the pseudocapacitance mechanism using synchrotron X-ray analytical techniques is proposed.
基金financially supported by Distinguished Young Scientists of Hunan Province(No.2022JJ10024)National Natural Science Foundation of China(No.21601057)+1 种基金Natural Science Foundation of Hunan Province(No.2021JJ30216)Key Projects of Hunan Provincial Education Department(No.22A0412).
文摘The design and development of energy storage device with high energy/power density has become a research hotspot.Zinc-ion hybrid capacitors(ZHCs)are considered as one of the most promising candidates.However,the application of ZHCs is hindered by their low energy density at high power density due to the unsatisfactory cathode material.In this study,a novel 3D phosphorus-doped carbon nanotube/reduced graphene oxide(P-CNT/rGO)aerogel cathode is synthesized through a synergistic modification strategy of CNT insertion and P doping modification combined with 3D porous design.The as-obtained P-CNT/rGO aerogel cathode manifests significantly increased surface aera,expanded interlayer spacing,and enhanced pseudocapacitance behavior,thus leading to significantly enhanced specific capacitance and superb ions transport performance.The as-assembled ZHC based on P-CNT/rGO cathode delivers a superior energy density of 42.2 Wh/kg at an extreme-high power density of 80 kW/kg and excellent cycle life.In-depth kinetic analyses are undertaken to prove the enhanced pseudocapacitance behavior and exceptional power output capability of ZHCs.Furthermore,the reaction mechanism of physical and chemical adsorption/desorption of electrolyte ions on the P-CNT/rGO cathode is revealed by systematic ex-situ characterizations.This work can provide a valuable reference for developing advanced graphene-based cathode for high energy/power density ZHCs.
基金supported by the Research Grants Council of the Hong Kong SAR Government(Early Career Scheme,#26309420,and General Research Fund,#16306921 and#16306022)the Department of Chemical and Biomolecular Engineering,HKUST(startup funding)+1 种基金sponsored by the Shanghai Jiao Tong University High-End Computing Center.Y.W.would like to thank the support from the National Natural Science Foundation of China(No.52102183,No.52281240409)the Natural Science Foundation of Shanghai(No.22ZR1433400).
文摘Drinking water contamination by heavy metals,particularly chromium and arsenic oxyanions,is a severe challenge threatening humanity’s sustainable development.Electrochemically mediated water purification is gaining attention due to its high uptake,rapid kinetics,modularity,and facile regeneration.Here,we designed a composite electrode by combining a redox-active/Faradaic polymer,poly(norbornene-diphenothiazine)(PNP_(2)),with carbon nanotubes(CNTs)–PNP_(2)-CNT.The PNP_(2)-CNT demonstrated exceptional pseudocapacitance behavior,resulting in significantly accelerated adsorption rates for dichromate(Cr(Ⅵ);0.008 gmg^(-1) min^(-1))and arsenite(As(Ⅲ);0.03 gmg^(-1) min^(-1)),surpassing reported materials by a margin of 3–200 times,while demonstrating a high adsorption capacity,666.3 and 612.4 mg g^(-1),respectively.Furthermore,it effectively converted As(Ⅲ)to the less toxic arsenate(As(Ⅴ))during adsorption and Cr(Ⅵ)to the less toxic chromium(Cr(Ⅲ))during desorption.This PNP_(2)-CNT system also showed significantly lower energy consumption,only 0.17%of the CNT control system.This study demonstrated for the first time the use of PNP_(2) redox-active polymers in the separation and conversion process,meeting the six criteria of high uptake,rapid kinetics,selectivity,stability,recyclability,and energy efficiency.This achievement expands the scope of advanced materials that address environmental concerns and make an impact by generating energy-and cost-effective water purification.
基金financially supported by the National Natural Science Foundation of China(No.U2004210)Application Foundation Frontier Project of Wuhan Science and Technology Program(No.2020010601012199)City University of Hong Kong Strategic Research Grant,Hong Kong,China(No.7005505)。
文摘Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.
基金National Natural Science Foundation of China,Grant/Award Numbers:22005256,22179113Fundamental Research Funds for the Central Universities,Grant/Award Number:20720210045Natural Science Foundation of Fujian Province of China,Grant/Award Number:2020J01034。
文摘Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-type mechanism for Na+storage in VN anodes but does not explain the phenomena of their size-dependent specific capacities and underlying causes of pseudocapacitive charge storage behaviors.Herein,we insightfully reveal the VN anode exhibits a surface-redox pseudocapacitive mechanism in nonaqueous,Na+-based electrolytes,as demonstrated by kinetics analysis,experimental observations,and first-principles calculations.Through ex situ X-ray photoelectron spectroscopy and semiquantitative analyses,the Na+storage is characterized by redox reactions occurring with the V5+/V4+to V3+at the surface of VN particles,which is different from the well-known conversion reaction mechanism.The pseudocapacitive performance is enhanced through nanoarchitecture design via oxidized vanadium states at the surface.The optimized VN-10 nm anode delivers a sodium-ion storage capability of 106 mAh g−1 at the high specific current of 20 A g−1,and excellent cycling performance of 5000 cycles with negligible capacity losses.This work demonstrates the emerging opportunities of utilizing pseudocapacitive charge storage for realizing high-rate sodium-ion storage applications.
基金the National Natural Science Foundation of China(Nos.51661009 and 21875097)the Natural Science Foundation of Guangxi Province(No.2019GXNSFDA245014)+1 种基金the Science and Technology Base and Talent Special Project of Guangxi Province(No.AD 19245162)the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen(No.JCYJ20200109141640095).
文摘Potassium-ion batteries(PIBs)are promising ne15t-generation energy storage candidates due to abundant resources and low cost.Sb-based materials with high theoretical capacity(660 mAh·g^(-1))and low working potential are considered as promising anode for PIBs.The remaining challenge is poor stability and slow kinetics.In this work,FeSb@N-doped carbon quantum dots anchored in three-dimensional(3D)porous N-doped carbon(FeSb@C/Nc3DC/N),a Sb-based material with a particular structure,is designed and constructed by a green salt-template method.As an anode for PIBs,it exhibits extraordinarily high-rate and long-cycle stability(a capacity of 245 mAh·g^(-1) at 3,080 mAh·g^(-1) after 1,000 cycles).The pseudocapacitance contribution(83%)is demonstrated as the origin of high-rate performance of the FeSb@C/NС3DC/N electrode.Furthermore,the potassium storage mechanism in the electrode is systematically investigated through ex-situ characterization techniques including ex-situ transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).Overall,this study could provide a useful guidance for future design of high-performance electrode materials for PIBs.
基金National Natural Science Foundation of China(grant nos.21805051 and 21875048)Outstanding Youth Project of Guangdong Natural Science Foundation(grant no.2020B1515020028)+3 种基金University Innovation Team Scientific Research Project of Guangzhou Education Bureau(grant no.202235246)Science and Technology Research Project of Guangzhou(grant nos.202102020376 and 202201020214)Guangdong University Student Science and Technology Innovation Climbing Program(grant no.pdjh2022b0415)2022 Innovation Training Program for College Students(grant no.s202211078133).
文摘Compressible supercapacitors play an increasingly significant role in flexible sensors and wearable electronic devices.However,the integration of mechanical compressibility and excellent electrochemical performance into a single device remains a challenge.Herein,we demonstrate a compressible and high-performance supercapacitor based on an N-doped carbon foam elastomer with hierarchical carbon nanotubes.Hierarchically structured Fe3C@N-doped carbon nanotubes/N-doped carbon foam and Ni@N-doped carbon nanotubes/N-doped carbon foam have been synthesized via a simple and universal self-catalytic strategy.The hierarchical structural features of self-catalytic N-doped carbon nanotubes serve as a cushion when the composite is subjected to an external force,exhibiting excellent mechanical properties with a maximum compressive strain of 80%and fatigue resistance of 1000 cycles.Moreover,the different electroactive potentials of the transition-metal species in the composites provide the assembly with a maximum operating voltage of 1.4 V,which shows a maximum energy density of∼10.74 Wh kg^(−1)(0.084 mWh cm^(−3))at the power density of∼179.2 W kg^(−1)(1.4 mWh cm^(−3)),and retains 88.4%of the original capacitance after 20,000 charge–discharge cycles,even at a strain of 80%.This work paves the way for controllable fabrication of compressible electrodes and supercapacitors.
基金supported by NRF-2021M3H4A1A03047333 and NRF-2022R1F1A1075084 of the National Research Foundation(NRF)of Korea funded by the Ministry of Science and ICT,Koreasupported by Semiconductor-Secondary Battery Interfacing Platform Technology Development Project of NNFC.
文摘Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This work presents an innovative Pseudocapacitive Sensor.The key lies in switching the energy storage kinetics from pseudocapacitor to electrical double layer capacitor by employing the change of local pH(-log[H^(+)])in MXene-based flexible supercapacitors during bending.Pseudocapacitive sensing is observed in acidic electrolyte but absent in neutral electrolyte.Applied shearing during bending causes liquid-crystalline MXene sheets to increase in their degree of anisotropic alignment.With blocking of H+mobility due to the higher diffusion barrier,local pH increases.The electrochemical energy storage kinetics transits from Faradaic chemical protonation(intercalation)to non-Faradaic physical adsorption.We utilize the phenomenon of capacitance change due to shifting energy storage kinetics for strain sensing purposes.The developed highly sensitive Pseudocapacitive Sensors feature a remarkable gauge factor(GF)of approximately 1200,far surpassing conventional strain sensors(GF:~1 for dielectric-cap sensor).The introduction of the Pseudocapacitive Sensor represents a paradigm shift,expanding the application of pseudocapacitance from being solely confined to energy devices to the realm of multifunctional electronics.This technological leap enriches our understanding of the pseudocapacitance mechanism of MXenes,and will drive innovation in cutting-edge technology areas,including advanced robotics,implantable biomedical devices,and health monitoring systems.
基金supported by the National Key R&D Program of China(Grant Nos.2023YFC3009900)National Natural Science Foundation of China(Grant Nos.61904116)+1 种基金Natural Science Foundation of Jiangsu Province(Grant Nos.BK20211029)the young scientific talent lifting project of Jiangsu Association for Science and Technology(Grant Nos.JSTJ-2023-018).
文摘Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.
基金financially supported by the National Natural Science Foundation of China(51108455,52106264)Civil Aviation Safety Capacity Building Fund(ADSA2022026)+2 种基金Liaoning Revitalization Talents Program(XLYC2018013)Liaoning Province AppliedFoundation Research Program Project(2023JH2/101300215)Unveiled the List of Local Service Projects from Education Department of Liaoning Province(JYTMS20230227)。
文摘The progression of anodes has markedly promoted the advancement of lithium-ion batteries(LIBs).Typical LIBs using carbon anodes cannot meet the continuously increasing demands for qualified safety and longevity.Spinel lithium titanate(LTO)is a strong contender to replace graphite anodes due to its optimal zero-strain merit and outstanding structural stability.Nevertheless,low reversible capacity and poor rate performance hinder the widespread application of LTO.Amazingly,the promising pseudocapacitive effect enables LTO to surmount the limit of theoretical capacity via boosted surface Li storage,contributing to observably upgraded energy and power densities in a wide temperature range.By leveraging the synergistic effect of multiple modification strategies to create additional active sites,the pseudocapacitive response of LTO can be markedly enhanced.This paper reviews the progress of pseudocapacitive LTO for the first time.We highlight the zero-strain characteristic and pseudocapacitance mechanism of LTO and review the design strategies of pseudocapacitive LTO.Significative issues for further developing pseudocapacitive LTO are proposed.It is worth noting that the pseudocapacitive contribution can greatly improve the low-temperature electrochemical performances of LTO.We anticipate that more efforts will be aroused to study the advanced pseudocapacitive LTO to accelerate the development of next-generation LIBs and energy storage devices.
基金support of Project Supported by Keypoint Research and Invention in Shaanxi Province of China(No.2020GY-270)this work was supported by the National Natural Science Foundation of China(No.U22A20144)。
文摘SnO_(2)is a potential anode material with high theoretical capacity for lithium-ion batteries(LIBs),however,its applications have been limited by the severe volume expansion during charging-discharging process.In this work,an inverse opal TiO_(2)/SnO_(2)composite with an interconnect network nanostructure was designed to confine Sn O_(2)nanoparticles in the porous TiO_(2).Due to this nanoconfinement structure,the volume expansion in the process was effectively alleviated,therefore the safety performance and cycling stability of the battery were effectively improved.At the same time,with a large number of microporous structures in the framework,the appearance of pseudocapacitance improves the rate performance and reversible capacity.In terms of electrochemical kinetics,its framework provides the connected path for charge migration,effectively reducing the charge transfer impedance,meanwhile,quantities of micropores in its skeleton could provide a smoother channel for lithium ions,thus greatly improving the diffusion rate of LIBs.The design of this nanostructure provides a new idea for the research of SnO_(2)-based anode with effectively enhanced electrochemical performance,which is promising anode for practical application.
