A dipole antenna with wideband characteristics is presented. The proposed antenna consists of a dipole with periodic capacitive loading and a pair of coplanar striplines （CPSs） as an impedance transformer. By adding...A dipole antenna with wideband characteristics is presented. The proposed antenna consists of a dipole with periodic capacitive loading and a pair of coplanar striplines （CPSs） as an impedance transformer. By adding interlaced coupling lines at each section, periodic capacitive loading is realized. The periodic interlaced coupling lines divide each arm of the dipole into five sections, and currents are distributed on different sections at different frequencies, which is useful to achieve a wide impedance bandwidth. By parametric study using HFSS, the optimized parameters of this dipole antenna are obtained. In order to validate the simulation results, a prototype of the proposed dipole antenna is fabricated and tested. The results show that the proposed antenna can achieve a gain of 3.1 dB–5.1 dB and bandwidth of 51% for ｜S 11 ｜ 10 dB over the band of 3.9 GHz–6.6 GHz, indicating its good radiation performance and radiation efficiency.展开更多
Sodium-ion hybrid capacitors(SICs)offer inherent energy-power synergy but are constrained by mismatched kinetics and life spans between the anode and cathode materials.Two-dimensional MoS_(2)@C composites demonstrate ...Sodium-ion hybrid capacitors(SICs)offer inherent energy-power synergy but are constrained by mismatched kinetics and life spans between the anode and cathode materials.Two-dimensional MoS_(2)@C composites demonstrate excellent kinetics and structural stability,thanks to the built-in electric field of the carbon heterostructure and its adaptability to volume changes.Yet,the carbon shell imposes a physical barrier to interfacial Na^(+)diffusion,while deep discharge induces the formation of crystalline Na_(2)S,accompanied by severe volumetric expansion and sluggish reversibility—factors that accelerate capacity fading and structural degradation.To address these challenges,a trace-level Ni doping strategy is introduced,enabling precise modulation of the composite's interlayer structure,electronic configuration,and reaction pathway.Ni incorporation expands the MoS_(2) interlayer spacing,reconstructs short-range ordered nanocrystals within a hierarchically porous network,and promotes Na^(+)diffusion by weakening interlayer van der Waals forces.Orbital hybridization between Ni-3d and Mo-4d/S-3p states enhances electronic conductivity and reduces charge transfer resistance.Critically,Ni doping enhances electron transfer from Ni to sulfur,which weakens Na–S bonds and promotes the formation of amorphous Na_(2)S,thereby suppressing crystalline Na_(2)S and enabling a reversible MoS_(2)/Na_(2)S conversion mechanism for improved structural stability and cycling performance.As a result,the optimized MoS_(2)-Ni@C anode delivers a high reversible capacity of 334 mAh g^(-1)at 10 A g^(-1)with 68%retention after 10,000 cycles.When assembled into a SIC device(MoS_(2)-Ni@C//AC),it achieves an energy density of 135 Wh kg^(-1)at a power density of 60.8 kW kg^(-1)(based on anode mass),with 76%retention over 3,000 cycles.展开更多
Carbon superstructures with multiscale hierarchies and functional attributes represent an appealing cathode candidate for zinc hybrid capacitors,but their tailor-made design to optimize the capacitive activity remains...Carbon superstructures with multiscale hierarchies and functional attributes represent an appealing cathode candidate for zinc hybrid capacitors,but their tailor-made design to optimize the capacitive activity remains a confusing topic.Here we develop a hydrogen-bond-oriented interfacial super-assembly strategy to custom-tailor nanosheet-intertwined spherical carbon superstructures(SCSs)for Zn-ion storage with double-high capacitive activity and durability.Tetrachlorobenzoquinone(H-bond acceptor)and dimethylbenzidine(H-bond donator)can interact to form organic nanosheet modules,which are sequentially assembled,orientally compacted and densified into well-orchestrated superstructures through multiple H-bonds(N-H···O).Featured with rich surface-active heterodiatomic motifs,more exposed nanoporous channels,and successive charge migration paths,SCSs cathode promises high accessibility of built-in zincophilic sites and rapid ion diffusion with low energy barriers(3.3Ωs-0.5).Consequently,the assembled Zn||SCSs capacitor harvests all-round improvement in Zn-ion storage metrics,including high energy density(166 Wh kg-1),high-rate performance(172 m Ah g^(-1)at 20 A g^(-1)),and long-lasting cycling lifespan(95.5%capacity retention after 500,000 cycles).An opposite chargecarrier storage mechanism is rationalized for SCSs cathode to maximize spatial capacitive charge storage,involving high-kinetics physical Zn^(2+)/CF_(3)SO_(3)-adsorption and chemical Zn^(2+)redox with carbonyl/pyridine groups.This work gives insights into H-bond-guided interfacial superassembly design of superstructural carbons toward advanced energy storage.展开更多
Modern power electronics,from electric vehicles to renewable energy systems,demand capacitors that can reliably store high energy at elevated temperatures.Polymer dielectrics are widely used in capacitors due to their...Modern power electronics,from electric vehicles to renewable energy systems,demand capacitors that can reliably store high energy at elevated temperatures.Polymer dielectrics are widely used in capacitors due to their high breakdown strength and ease of processing,but they traditionally suffer from poor energy density at high temperatures[1-4].展开更多
Transition metal selenides as sodium-ion hybrid capacitor(SIHC)anodes still suffer from amorphization difficulties and capacity degradation triggered by polyselenide dissolution.Herein,an atomistic amorphous strategy ...Transition metal selenides as sodium-ion hybrid capacitor(SIHC)anodes still suffer from amorphization difficulties and capacity degradation triggered by polyselenide dissolution.Herein,an atomistic amorphous strategy is proposed to construct adjacent Nb-Nb diatomic pairs with Se/O-coordination(Se4-Nb2-O2)in N-doped carbon-confined amorphous selenide clusters(a-Nb-Se/O@NC).Synergistic carbon confinement and hydrothermal oxygenation induce amorphization of Nb–Se bonds,eliminating crystalline rigidity while creating isotropic dual-ion transport channels and high-density active sites enriched with dangling bonds,thereby enhancing structural integrity and Na+storage capacity.The unique Se/O-coordinated Nb-Nb diatomic configuration establishes an electron-delocalized system,where the low electronegativity of Se counterbalances electron withdrawal from coordinated O at Nb centers.These strengthen d-p orbital hybridization,reduce Na+adsorption energy,and optimize charge transfer pathways and reaction kinetics in the amorphous clusters.Electrochemical tests reveal that the a-Nb-Se/O@NC anode delivers a high reversible capacity of 312.57 mAh g^(−1)and exceptional cyclic stability(103%capacity retention)after 5000 cycles at 10.0 A g^(−1).Assembled SIHCs achieve outstanding energy/power densities(207.1 Wh kg^(−1)/18966 W kg^(−1)),surpassing most amorphous and crystalline counterparts.This work provides methodological insights for the design of electrodes in high-power storage devices through atomic modulation and electronic optimization of amorphous selenides.展开更多
Metal-insulator-metal aluminium electrolytic capacitors(MIM-AECs)combine high capacity-density and high breakdown field strength of solid AECs with high-frequency responsibility,wide workingtemperature window and wate...Metal-insulator-metal aluminium electrolytic capacitors(MIM-AECs)combine high capacity-density and high breakdown field strength of solid AECs with high-frequency responsibility,wide workingtemperature window and waterproof properties of MIM nanocapacitors.However,interfacial atomic diffusion poses a major obstacle,preventing the high-voltage MIM-AECs exploitation and thereby hampering their potential and advantages in high-power and high-energy-density applications.Here,an innovative high-voltage MIM-AECs were fabricated.The AlPO_(4)buffer layer is formed on AlO(OH)/AAO/Al surface by using H_(3)PO_(4)treatment,then a stable van der Waals(vdW)SnO_(2)/AlPO_(4)/AAO/Al multilayer was constructed via atomic layer deposition(ALD)technology.Due to higher diffusion barrier and lower carrier migration of SnO_(2)/AlPO_(4)/AAO interfaces,Sn atom diffusion is inhibited and carrier acceleration by electric field is weakened,guaranteeing high breakdown field strength of dielectric AAO and avoiding local breakdown risks.Through partial etching to hydrated AlO(OH)by H_(3)PO_(4)treatment,the tunnel was further opened up to facilitate subsequent ALD-SnO_(2)entry,thus obtaining a high SnO_(2)coverage.The SnO_(2)/AlPO_(4)/AAO/Al capacitors show a comprehensive performance in high-voltage(260 V),hightemperature(335℃),high-humidity(100%RH)and high-frequency response(100 k Hz),outperforming commercial solid-state AECs,and high-energy density(8.6μWh/cm^(2)),markedly exceeding previously reported MIM capacitors.The work lays the foundation for next-generation capacitors with highvoltage,high-frequency,high-temperature and high-humidity resistance.展开更多
In the context of rapid economic development,the pursuit of sustainable energy solutions has become a major challenge.Lithium-ion capacitors(LICs),which integrate the high energy density of lithium-ion batteries with ...In the context of rapid economic development,the pursuit of sustainable energy solutions has become a major challenge.Lithium-ion capacitors(LICs),which integrate the high energy density of lithium-ion batteries with the high power density of supercapacitors,have emerged as promising candidates.However,challenges such as poor capacity matching and limited energy density still hinder their practical application.Carbon nanofibers(CNFs),with their high specific surface area,excellent electrical conductivity,mechanical flexibility,and strong compatibility with active materials,are regarded as ideal electrode frameworks for LICs.This review summarizes key strategies to improve the electrochemical performance of CNF-based LICs,including structural engineering,heteroatom doping,and hybridization with transition metal oxides.The underlying mechanisms of each approach are discussed in detail,with a focus on their roles in improving capacitance,energy density,and cycling stability.This review aims to provide insights into material design and guide future research toward high-performance LICs for next-generation energy storage applications.展开更多
Lithium-ion capacitors(LICs)combine the high power dens-ity of electrical double-layer capacitors with the high energy density of lithium-ion batteries.However,they face practical limitations due to the narrow operati...Lithium-ion capacitors(LICs)combine the high power dens-ity of electrical double-layer capacitors with the high energy density of lithium-ion batteries.However,they face practical limitations due to the narrow operating voltage window of their activated carbon(AC)cathodes.We report a scalable thermal treatment strategy to develop high-voltage-tolerant AC cathodes.Through controlled thermal treatment of commer-cial activated carbon(Raw-AC)under a H_(2)/Ar atmosphere at 400-800℃,the targeted reduction of degradation-prone functional groups can be achieved while preserving the critical pore structure and increasing graph-itic microcrystalline ordering.The AC treated at 400℃(HAC-400)had a significant increase in specific capacity(96.0 vs.75.1 mAh/g at 0.05 A/g)and better rate capability(61.1 vs.36.1 mAh/g at 5 A/g)in half-cell LICs,along with an 83.5%capacity retention over 7400 cycles within an extended voltage range of 2.0-4.2 V in full-cell LICs.Scalability was demonstrated by a 120 g batch production,enabling fabrication of pouch-type LICs with commercial hard carbon anodes that delivered a higher energy density of 28.3 Wh/kg at 1 C,and a peak power density of 12.1 kW/kg compared to devices using raw AC.This simple,industry-compatible approach may be used for producing ad-vanced cathode materials for practical high-performance LICs.展开更多
The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively ...The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively applying mono-capacitor positioning, multiple positioning and reconfiguration processes using GA-based algorithms implemented in a Matlab environment. From the diagnostic study of this network, it was observed that a minimum voltage of 0.90 pu induces a voltage deviation of 5.26%, followed by active and reactive losses of 425.08 kW and 435.09 kVAR, respectively. Single placement with the NSGAII resulted in the placement of a 3000 kVAR capacitor at node 128, which proved to be the invariably neuralgic point. Multiple placements resulted in a 21.55% reduction in losses and a 0.74% regression in voltage profile performance. After topology optimization, the loss profile improved by 65.08% and the voltage profile improved by 1.05%. Genetic algorithms are efficient and effective tools for improving the performance of distribution networks, whose degradation is often dynamic due to the natural variability of loads.展开更多
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
Submodule capacitor aging poses significant challenges to the safe operation of modular multilevel converter(MMC)systems.Traditional detection methods rely predominantly on offline tests,lacking real-time evaluation c...Submodule capacitor aging poses significant challenges to the safe operation of modular multilevel converter(MMC)systems.Traditional detection methods rely predominantly on offline tests,lacking real-time evaluation capabilities.Moreover,existing online approaches require additional sampling channels,thereby increasing system complexity and costs.To address these issues,this paper proposes an online evaluation method for submodule capacitor aging based on CapAgingNet.Initially,an MMC system simulation platform is developed to examine the effects of submodule capacitor aging on system operational characteristics and to create a dataset of submodule capacitor switching states.Subsequently,the CapAgingNet model is introduced,incorporating key technical modules to enhance performance:the Deep Stem module,which extracts larger receptive fields through multiple convolution layers and mitigates the impact of data sparsity in capacitor aging on feature extraction;the efficient channel attention(ECA)module,utilizing onedimensional convolution for dynamic weighting to adjust the importance of each channel,thereby enhancing the ability of the model to process high-dimensional features in capacitor aging data;and the multiscale feature fusion(MSF)module,which integrates capacitor aging information across different scales by combining fine-grained and coarse-grained features,thus improving the capacity of the model to capture high-frequency variation characteristics.The experimental results reveal that the CapAgingNet model achieves a TOP-1 accuracy of 95.32%and a macro-averaged F1 score of 95.49%on the test set,thereby providing effective technical support for online monitoring of submodule capacitor aging.展开更多
Reconfiguration,as well as optimal utilization of distributed generation sources and capacitor banks,are highly effective methods for reducing losses and improving the voltage profile,or in other words,the power quali...Reconfiguration,as well as optimal utilization of distributed generation sources and capacitor banks,are highly effective methods for reducing losses and improving the voltage profile,or in other words,the power quality in the power distribution system.Researchers have considered the use of distributed generation resources in recent years.There are numerous advantages to utilizing these resources,the most significant of which are the reduction of network losses and enhancement of voltage stability.Non-dominated Sorting Genetic Algorithm II(NSGA-II),Multi-Objective Particle Swarm Optimization(MOPSO),and Intersect Mutation Differential Evolution(IMDE)algorithms are used in this paper to perform optimal reconfiguration,simultaneous location,and capacity determination of distributed generation resources and capacitor banks.Three scenarios were used to replicate the studies.The reconfiguration of the switches,as well as the location and determination of the capacitor bank’s optimal capacity,were investigated in this scenario.However,in the third scenario,reconfiguration,and determining the location and capacity of the Distributed Generation(DG)resources and capacitor banks have been carried out simultaneously.Finally,the simulation results of these three algorithms are compared.The results indicate that the proposed NSGAII algorithm outperformed the other two multi-objective algorithms and was capable of maintaining smaller objective functions in all scenarios.Specifically,the energy losses were reduced from 211 to 51.35 kW(a 75.66%reduction),119.13 kW(a 43.54%reduction),and 23.13 kW(an 89.04%reduction),while the voltage stability index(VSI)decreased from 6.96 to 2.105,1.239,and 1.257,respectively,demonstrating significant improvement in the voltage profile.展开更多
Zinc-ion hybrid capacitors (ZIHCs) have received increasing attention as energy storage devices owing to their low cost,high safety,and environmental friendliness.However,their progress has been hampered by low energy...Zinc-ion hybrid capacitors (ZIHCs) have received increasing attention as energy storage devices owing to their low cost,high safety,and environmental friendliness.However,their progress has been hampered by low energy and power density,as well as unsatisfactory long-cycle stability,mainly due to the lack of suitable electrode materials.In this context,we have developed manganese single atoms implanted in nitrogen-doped porous carbon nanosheets (MnSAs/NCNs) using a metal salt template method as cathodes for ZIHCs.The metal salt serves a dual purpose in the synthesis process:It facilitates the uniform dispersion of Mn atoms within the carbon matrix and acts as an activating agent to create the porous structure.When applied in ZIHCs,the MnSAs/NCNs electrode demonstrates exceptional performance,including a high capacity of 203 m Ah g^(-1),an energy density of 138 Wh kg^(-1)at 68 W kg^(-1),and excellent cycle stability with 91%retention over 10,000 cycles.Theoretical calculations indicate that the introduced Mn atoms modulate the local charge distribution of carbon materials,thereby improving the electrochemical property.This work demonstrates the significant potential of carbon materials with metal atoms in zinc-ion hybrid capacitors,not only in enhancing electrochemical performance but also in providing new insights and methods for developing high-performance energy storage devices.展开更多
Zinc-ion capacitors have gained significant interest because of the exceptional capacity of zinc,the safety of aqueous electrolytes,and the low cost of carbon materials.However,the low capacity of carbon materials gre...Zinc-ion capacitors have gained significant interest because of the exceptional capacity of zinc,the safety of aqueous electrolytes,and the low cost of carbon materials.However,the low capacity of carbon materials greatly limits the energy density of the capacitors.Structural modification or introduction of heteroatom doping to carbon materials sacrifices their volumetric density and cycling stability.Here,we introduce soluble methylene blue(MB)into the electrolyte of the carbon electrode to enhance the capacity by utilizing its redox reactions at the interface.Adding MB increases the electrode capacity to118 m A·h·g^(-1),3.8 times higher compared to that without MB.Importantly,AC electrode with MB delivers an ultrahigh cycling stability with a retention of 90%after 12000 cycles.In situ and ex situ characterization indicates that MB undergoes reversible structural changes during the processes.Theoretical calculations further demonstrate that the reaction of MB discharging process involves two electrons and two protons,going through a radical intermediate state.Assembled Zn//AC capacitor with MB achieves a maximum capacity of 137 m A·h·g^(-1),3.4 times higher compared to the capacitor without MB.Additionally,the capacitor with MB exhibits an energy density of 105.8 W·h·kg^(-1),three times higher than that without MB.Moreover,the capacitor exhibits outstanding cycling stability,retaining92%of the capacity even after 8000 cycles.Our results demonstrate that MB can effectively promote the energy density of the capacitor without sacrificing its cycling stability.展开更多
Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Effi...Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Efficient potassium activation is the key to develop high-performance oxygen-rich porous carbon cathodes.Herein,the alkali lignin,extracted from eucalyptus wood by geopolymer-assisted low-alkali pretreatment,is used to prepare oxygen-rich lignin-derived porous carbons(OLPCs)through KOH activation and K_(2)CO_(3)activation at 700-900℃.KOH activation constructs a hierarchical micro-mesoporous structure,while K_(2)CO_(3)activation constructs a microporous structure.Furthermore,K_(2)CO_(3)activation could more efficiently construct active oxygen(C=O)species than KOH activation.The OLPCs prepared by KOH/K_(2)CO_(3)activations at 800℃show the highest microporosity(78.4/87.7%)and C=O content(5.3/8.0 at.%).Due to that C=O and micropore adsorb zinc ions,the OLPCs prepared by K_(2)CO_(3)activation at 800℃with higher C=O content and microporosity deliver superior capacitive performance(256 F g^(-1)at 0.1 A g^(-1))than that by KOH activation at 800℃(224 F g^(-1)at 0.1 A g^(-1)),and excellent cycling stability.This work provides a new insight into the sustainable preparation of oxygenrich porous carbon cathodes through efficient potassium activation for ZIHCs.展开更多
Zinc-ion capacitors(ZICs)are promising energy storage devices due to their balance between the energy and power densities inherited from Zn-ion batteries and supercapacitors,respectively.However,the low specific capac...Zinc-ion capacitors(ZICs)are promising energy storage devices due to their balance between the energy and power densities inherited from Zn-ion batteries and supercapacitors,respectively.However,the low specific capacitance of carbon cathode materials and the dendrite growth on Zn anode have set fatal drawbacks to their energy density and cycle stability.Herein,we demonstrate that,in 1 M Zn(CF_(3)SO_(3))_(2)/DMF(N,N-dimethylformamide)electrolyte,confining oxygen in carbon cathode materials via high-energy ball milling can synergistically introduce additional pseudocapacitance on the cathode side while suppressing the dendrite growth on Zn anode side,which jointly lead to high energy density(94 Wh kg^(−1)at 448 W kg^(−1))and long cycle stability of ZICs.The hydroxyl group in carbon cathode can be transformed to C–O–Zn together with the release of protons during the initial discharge,which in turn stimulates the defluorination of CF_(3)SO_(3)^(-)anions and formation of ZnF_(2)on both cathode and anode.The ZnF2 formed on the surface of the Zn anode suppresses the dendrite growth by regulating the Zn^(2+)deposition/stripping in a reticular structure,resulting in the excellent cycle stability.This work provides a facile strategy to rationally design and construct high energy and stable ZICs through engineering the oxygen-bearing functional groups in carbon cathode materials.展开更多
Developing high-performance anode materials is crucial for the advancement of sodium-ion capacitors with high-energy density and large power density.Bimetallic oxides exhibit a high specific capacity due to their syne...Developing high-performance anode materials is crucial for the advancement of sodium-ion capacitors with high-energy density and large power density.Bimetallic oxides exhibit a high specific capacity due to their synergistic effects in electrochemical processes.However,challenges such as poor electrical conductivity,slow ion transport,and volume expansion severely limit their development.In this study,Co_(2)VO_(4)@C-1.5 was synthesized through a straightforward method involving solvent-heating and carbonization via calcination.The synergistic effect of Co and V,mitigation of volume expansion by the carbon-coated layer,enhancement of pseudocapacitive behavior and improved electrical conductivity of Co_(2)VO_(4)@C-1.5 contribute to its superior electrochemical performance.The specific capacity of Co_(2)VO_(4)@C-1.5 remained steady at 288.8 and 171.7 mAh g^(-1)after 100 and 500 cycles at 100 and 1000 mA g^(-1),respectively.Density functional theory(DFT)calculations show a notable reduction in the energy barrier of Co_(2)VO_(4)@C-1.5.Furthermore,the assembled sodium-ion capacitor Co_(2)VO_(4)@C-1.5//AC demonstrates high-energy density(108.5 Wh kg^(-1)at 99.8 W kg^(-1)),remarkable power density(38.2 Wh kg^(-1)at 12,000 W kg^(-1)),and longcycle stability(capacity retention of 80.6%after 6000 cycles).The design and optimization of the carbon-coated structure provide valuable insights for the development of bimetallic oxide materials in sodium-ion capacitors(SICs).展开更多
Low specific capacitances and/or limited working potential(≤4.5 V).of the prevalent carbon-based positive electrodes as the inborn bottleneck seriously hinder practical advancement of lithium-ion capacitors.Thus,brea...Low specific capacitances and/or limited working potential(≤4.5 V).of the prevalent carbon-based positive electrodes as the inborn bottleneck seriously hinder practical advancement of lithium-ion capacitors.Thus,breakthroughs in enhancement of both specific capacitances and upper cutoff potentials are enormously significant for high-energy density lithium-ion capacitors.Herein,we first meticulously design and scalably fabricate a commercializable fluorine-doped porous carbon material with competitive tap density,large active surface,appropriate aperture distribution,and promoted affinity with the electrolyte,rendering its abundant electroactive inter-/surface and rapid PF_(6)^(-)transport.Theoretical calculations authenticate that fluorine-doped porous carbon possesses lower PF_(6)^(-)adsorption energy and stronger interaction with PF_(6)^(-).Thanks to the remarkable structural/compositional superiority,when served as a positive electrode toward lithium-ion capacitors,the commercial-level fluorine-doped porous carbon showcases the record-breaking electrochemical properties within a wider working window of 2.5-5.0 V(vs Li/Li^(+))in terms of high-rate specific capacitances and long-duration stability,much superior to commercial activated carbon.More significantly,the 4.5 V-class graphite//fluorine-doped porous carbon lithium-ion capacitors are first constructed and manifest competitive electrochemical behaviors with long-cycle life,modest polarization,and large energy density.Our work provides a commendable positive paradigm and contributes a major step forward in next-generation lithium-ion capacitors and even other high-energy density metal-ion capacitors.展开更多
The rise of Zn-ion hybrid capacitor(ZHC)has imposed high requirements on carbon cathodes,including reasonable configuration,high specific surface area,multiscale pores,and abundant defects.To achieve this objective,a ...The rise of Zn-ion hybrid capacitor(ZHC)has imposed high requirements on carbon cathodes,including reasonable configuration,high specific surface area,multiscale pores,and abundant defects.To achieve this objective,a template-oriented strategy coupled with multi-heteroatom modification is proposed to precisely synthesize a three-dimensional boron/nitrogen-rich carbon nanoflake-interconnected micro/nano superstructure,referred to as BNPC.The hierarchically porous framework of BNPC shares short channels for fast Zn2+transport,increased adsorption-site accessibility,and structural robustness.Additionally,the boron/nitrogen incorporation effect significantly augments Zn2+adsorption capability and more distinctive pseudocapacitive nature,notably enhancing Zn-ion storage and transmission kinetics by performing the dual-storage mechanism of the electric double-layer capacitance and Faradaic redox process in BNPC cathode.These merits contribute to a high capacity(143.7 mAh g^(-1)at 0.2 A g^(-1))and excellent rate capability(84.5 mAh g^(-1)at 30 A g^(-1))of BNPC-based aqueous ZHC,and the ZHC still shows an ultrahigh capacity of 108.5 mAh g^(-1)even under a high BNPC mass loading of 12 mg cm^(-2).More critically,the BNPC-based flexible device also sustains notable cyclability over 30,000 cycles and low-rate self-discharge of 2.13 mV h-1 along with a preeminent energy output of 117.15 Wh kg^(-1)at a power density of 163.15Wkg^(-1),favoring a creditable applicability in modern electronics.In/ex-situ analysis and theoretical calculations elaborately elucidate the enhanced charge storage mechanism in depth.The findings offer a promising platform for the development of advanced carbon cathodes and corresponding electrochemical devices.展开更多
1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with...1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with enlarged interlayer spacing,vertically bonded to reduced graphene oxide(rGO)(1T-MoS_(2)/rGO),were designed using a hydrothermal-assisted dispersion and intercalation strategy.The active nitrogen species derived from N,N-dimethylformamide(DMF)not only bridge the rGO and MoS_(2)through strong Mo-N-C bonds to promote the formation of dispersed MoS_(2)nanosheets,but also intercalate into the MoS_(2)structure,further enlarging the interlayer spacing.This unique structure synergistically enhances meso-and microscale mass transfer outside and inside of the few-layered nanosheets,significantly improving electrochemical reaction kinetics and reducing the kinetic mismatch between the anode and cathode.Consequently,the resulting 1T-MoS_(2)/rGO achieves a capacity of 500 mAh g^(-1)after 500 cycles at 5 A g^(-1)and a high rate performance of 587 mAh g^(-1)at a high rate of 10 A g^(-1).Moreover,the assembled 3D vertical 1T-MoS_(2)/rGO//AC LIC delivers a high energy density of 100.3 Wh kg^(-1)at a power density of1.0 kW kg^(-1),and long cycle stability with capacity retention as high as 91.02%after 5000 cycles at 2 A g^(-1).This work provides a generalizable strategy for engineering two-dimensional material-based electrodes,offering new insights into high-performance energy storage systems.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61172115 and 60872029)the High-Tech Research and Development Program of China (Grant No. 2008AA01Z206)the Aeronautics Foundation of China (Grant No. 20100180003)
文摘A dipole antenna with wideband characteristics is presented. The proposed antenna consists of a dipole with periodic capacitive loading and a pair of coplanar striplines （CPSs） as an impedance transformer. By adding interlaced coupling lines at each section, periodic capacitive loading is realized. The periodic interlaced coupling lines divide each arm of the dipole into five sections, and currents are distributed on different sections at different frequencies, which is useful to achieve a wide impedance bandwidth. By parametric study using HFSS, the optimized parameters of this dipole antenna are obtained. In order to validate the simulation results, a prototype of the proposed dipole antenna is fabricated and tested. The results show that the proposed antenna can achieve a gain of 3.1 dB–5.1 dB and bandwidth of 51% for ｜S 11 ｜ 10 dB over the band of 3.9 GHz–6.6 GHz, indicating its good radiation performance and radiation efficiency.
基金supported by the Carbon Emission Peak and Neutrality of Jiangsu Province(BE2022031-4)the National Natural Science Foundation of China(Key Program)(52131306,52122209,52403001)+1 种基金the Project on National Key R&D Program of China(2021YFB2400400)the Cultivation Program for The Excellent Doctoral Dissertation of Nanjing Tech University。
文摘Sodium-ion hybrid capacitors(SICs)offer inherent energy-power synergy but are constrained by mismatched kinetics and life spans between the anode and cathode materials.Two-dimensional MoS_(2)@C composites demonstrate excellent kinetics and structural stability,thanks to the built-in electric field of the carbon heterostructure and its adaptability to volume changes.Yet,the carbon shell imposes a physical barrier to interfacial Na^(+)diffusion,while deep discharge induces the formation of crystalline Na_(2)S,accompanied by severe volumetric expansion and sluggish reversibility—factors that accelerate capacity fading and structural degradation.To address these challenges,a trace-level Ni doping strategy is introduced,enabling precise modulation of the composite's interlayer structure,electronic configuration,and reaction pathway.Ni incorporation expands the MoS_(2) interlayer spacing,reconstructs short-range ordered nanocrystals within a hierarchically porous network,and promotes Na^(+)diffusion by weakening interlayer van der Waals forces.Orbital hybridization between Ni-3d and Mo-4d/S-3p states enhances electronic conductivity and reduces charge transfer resistance.Critically,Ni doping enhances electron transfer from Ni to sulfur,which weakens Na–S bonds and promotes the formation of amorphous Na_(2)S,thereby suppressing crystalline Na_(2)S and enabling a reversible MoS_(2)/Na_(2)S conversion mechanism for improved structural stability and cycling performance.As a result,the optimized MoS_(2)-Ni@C anode delivers a high reversible capacity of 334 mAh g^(-1)at 10 A g^(-1)with 68%retention after 10,000 cycles.When assembled into a SIC device(MoS_(2)-Ni@C//AC),it achieves an energy density of 135 Wh kg^(-1)at a power density of 60.8 kW kg^(-1)(based on anode mass),with 76%retention over 3,000 cycles.
基金financially supported by the National Natural Science Foundation of China(Nos.22272118,22172111,and 22309134)the Science and Technology Commission of Shanghai Municipality,China(Nos.22ZR1464100,20ZR1460300,and 19DZ2271500)+2 种基金the China Postdoctoral Science Foundation(2022M712402),the Shanghai Rising-Star Program(23YF1449200)the Zhejiang Provincial Science and Technology Project(2022C01182)the Fundamental Research Funds for the Central Universities(2023-3-YB-07)。
文摘Carbon superstructures with multiscale hierarchies and functional attributes represent an appealing cathode candidate for zinc hybrid capacitors,but their tailor-made design to optimize the capacitive activity remains a confusing topic.Here we develop a hydrogen-bond-oriented interfacial super-assembly strategy to custom-tailor nanosheet-intertwined spherical carbon superstructures(SCSs)for Zn-ion storage with double-high capacitive activity and durability.Tetrachlorobenzoquinone(H-bond acceptor)and dimethylbenzidine(H-bond donator)can interact to form organic nanosheet modules,which are sequentially assembled,orientally compacted and densified into well-orchestrated superstructures through multiple H-bonds(N-H···O).Featured with rich surface-active heterodiatomic motifs,more exposed nanoporous channels,and successive charge migration paths,SCSs cathode promises high accessibility of built-in zincophilic sites and rapid ion diffusion with low energy barriers(3.3Ωs-0.5).Consequently,the assembled Zn||SCSs capacitor harvests all-round improvement in Zn-ion storage metrics,including high energy density(166 Wh kg-1),high-rate performance(172 m Ah g^(-1)at 20 A g^(-1)),and long-lasting cycling lifespan(95.5%capacity retention after 500,000 cycles).An opposite chargecarrier storage mechanism is rationalized for SCSs cathode to maximize spatial capacitive charge storage,involving high-kinetics physical Zn^(2+)/CF_(3)SO_(3)-adsorption and chemical Zn^(2+)redox with carbonyl/pyridine groups.This work gives insights into H-bond-guided interfacial superassembly design of superstructural carbons toward advanced energy storage.
文摘Modern power electronics,from electric vehicles to renewable energy systems,demand capacitors that can reliably store high energy at elevated temperatures.Polymer dielectrics are widely used in capacitors due to their high breakdown strength and ease of processing,but they traditionally suffer from poor energy density at high temperatures[1-4].
基金supported by the National Natural Science Foundation of China(Grant No.52573299)the Natural Science Foundation of Jiangxi province(No.20242BAB25223,20232BCJ23025,20232BCJ25040,20232BAB214024)the Special Funding Program for Graduate Student Innovation of Jiangxi Province(No.YC2024-S594).
文摘Transition metal selenides as sodium-ion hybrid capacitor(SIHC)anodes still suffer from amorphization difficulties and capacity degradation triggered by polyselenide dissolution.Herein,an atomistic amorphous strategy is proposed to construct adjacent Nb-Nb diatomic pairs with Se/O-coordination(Se4-Nb2-O2)in N-doped carbon-confined amorphous selenide clusters(a-Nb-Se/O@NC).Synergistic carbon confinement and hydrothermal oxygenation induce amorphization of Nb–Se bonds,eliminating crystalline rigidity while creating isotropic dual-ion transport channels and high-density active sites enriched with dangling bonds,thereby enhancing structural integrity and Na+storage capacity.The unique Se/O-coordinated Nb-Nb diatomic configuration establishes an electron-delocalized system,where the low electronegativity of Se counterbalances electron withdrawal from coordinated O at Nb centers.These strengthen d-p orbital hybridization,reduce Na+adsorption energy,and optimize charge transfer pathways and reaction kinetics in the amorphous clusters.Electrochemical tests reveal that the a-Nb-Se/O@NC anode delivers a high reversible capacity of 312.57 mAh g^(−1)and exceptional cyclic stability(103%capacity retention)after 5000 cycles at 10.0 A g^(−1).Assembled SIHCs achieve outstanding energy/power densities(207.1 Wh kg^(−1)/18966 W kg^(−1)),surpassing most amorphous and crystalline counterparts.This work provides methodological insights for the design of electrodes in high-power storage devices through atomic modulation and electronic optimization of amorphous selenides.
基金supported by the National Natural Science Foundation of China(52477221,52202296)the Natural Science Foundation of Shaanxi Province(2023KXJ-246,2022JQ-048)。
文摘Metal-insulator-metal aluminium electrolytic capacitors(MIM-AECs)combine high capacity-density and high breakdown field strength of solid AECs with high-frequency responsibility,wide workingtemperature window and waterproof properties of MIM nanocapacitors.However,interfacial atomic diffusion poses a major obstacle,preventing the high-voltage MIM-AECs exploitation and thereby hampering their potential and advantages in high-power and high-energy-density applications.Here,an innovative high-voltage MIM-AECs were fabricated.The AlPO_(4)buffer layer is formed on AlO(OH)/AAO/Al surface by using H_(3)PO_(4)treatment,then a stable van der Waals(vdW)SnO_(2)/AlPO_(4)/AAO/Al multilayer was constructed via atomic layer deposition(ALD)technology.Due to higher diffusion barrier and lower carrier migration of SnO_(2)/AlPO_(4)/AAO interfaces,Sn atom diffusion is inhibited and carrier acceleration by electric field is weakened,guaranteeing high breakdown field strength of dielectric AAO and avoiding local breakdown risks.Through partial etching to hydrated AlO(OH)by H_(3)PO_(4)treatment,the tunnel was further opened up to facilitate subsequent ALD-SnO_(2)entry,thus obtaining a high SnO_(2)coverage.The SnO_(2)/AlPO_(4)/AAO/Al capacitors show a comprehensive performance in high-voltage(260 V),hightemperature(335℃),high-humidity(100%RH)and high-frequency response(100 k Hz),outperforming commercial solid-state AECs,and high-energy density(8.6μWh/cm^(2)),markedly exceeding previously reported MIM capacitors.The work lays the foundation for next-generation capacitors with highvoltage,high-frequency,high-temperature and high-humidity resistance.
文摘In the context of rapid economic development,the pursuit of sustainable energy solutions has become a major challenge.Lithium-ion capacitors(LICs),which integrate the high energy density of lithium-ion batteries with the high power density of supercapacitors,have emerged as promising candidates.However,challenges such as poor capacity matching and limited energy density still hinder their practical application.Carbon nanofibers(CNFs),with their high specific surface area,excellent electrical conductivity,mechanical flexibility,and strong compatibility with active materials,are regarded as ideal electrode frameworks for LICs.This review summarizes key strategies to improve the electrochemical performance of CNF-based LICs,including structural engineering,heteroatom doping,and hybridization with transition metal oxides.The underlying mechanisms of each approach are discussed in detail,with a focus on their roles in improving capacitance,energy density,and cycling stability.This review aims to provide insights into material design and guide future research toward high-performance LICs for next-generation energy storage applications.
文摘Lithium-ion capacitors(LICs)combine the high power dens-ity of electrical double-layer capacitors with the high energy density of lithium-ion batteries.However,they face practical limitations due to the narrow operating voltage window of their activated carbon(AC)cathodes.We report a scalable thermal treatment strategy to develop high-voltage-tolerant AC cathodes.Through controlled thermal treatment of commer-cial activated carbon(Raw-AC)under a H_(2)/Ar atmosphere at 400-800℃,the targeted reduction of degradation-prone functional groups can be achieved while preserving the critical pore structure and increasing graph-itic microcrystalline ordering.The AC treated at 400℃(HAC-400)had a significant increase in specific capacity(96.0 vs.75.1 mAh/g at 0.05 A/g)and better rate capability(61.1 vs.36.1 mAh/g at 5 A/g)in half-cell LICs,along with an 83.5%capacity retention over 7400 cycles within an extended voltage range of 2.0-4.2 V in full-cell LICs.Scalability was demonstrated by a 120 g batch production,enabling fabrication of pouch-type LICs with commercial hard carbon anodes that delivered a higher energy density of 28.3 Wh/kg at 1 C,and a peak power density of 12.1 kW/kg compared to devices using raw AC.This simple,industry-compatible approach may be used for producing ad-vanced cathode materials for practical high-performance LICs.
文摘The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively applying mono-capacitor positioning, multiple positioning and reconfiguration processes using GA-based algorithms implemented in a Matlab environment. From the diagnostic study of this network, it was observed that a minimum voltage of 0.90 pu induces a voltage deviation of 5.26%, followed by active and reactive losses of 425.08 kW and 435.09 kVAR, respectively. Single placement with the NSGAII resulted in the placement of a 3000 kVAR capacitor at node 128, which proved to be the invariably neuralgic point. Multiple placements resulted in a 21.55% reduction in losses and a 0.74% regression in voltage profile performance. After topology optimization, the loss profile improved by 65.08% and the voltage profile improved by 1.05%. Genetic algorithms are efficient and effective tools for improving the performance of distribution networks, whose degradation is often dynamic due to the natural variability of loads.
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supported by China Yangtze Power Co.,Ltd.(No.ZSF2502001).
文摘Submodule capacitor aging poses significant challenges to the safe operation of modular multilevel converter(MMC)systems.Traditional detection methods rely predominantly on offline tests,lacking real-time evaluation capabilities.Moreover,existing online approaches require additional sampling channels,thereby increasing system complexity and costs.To address these issues,this paper proposes an online evaluation method for submodule capacitor aging based on CapAgingNet.Initially,an MMC system simulation platform is developed to examine the effects of submodule capacitor aging on system operational characteristics and to create a dataset of submodule capacitor switching states.Subsequently,the CapAgingNet model is introduced,incorporating key technical modules to enhance performance:the Deep Stem module,which extracts larger receptive fields through multiple convolution layers and mitigates the impact of data sparsity in capacitor aging on feature extraction;the efficient channel attention(ECA)module,utilizing onedimensional convolution for dynamic weighting to adjust the importance of each channel,thereby enhancing the ability of the model to process high-dimensional features in capacitor aging data;and the multiscale feature fusion(MSF)module,which integrates capacitor aging information across different scales by combining fine-grained and coarse-grained features,thus improving the capacity of the model to capture high-frequency variation characteristics.The experimental results reveal that the CapAgingNet model achieves a TOP-1 accuracy of 95.32%and a macro-averaged F1 score of 95.49%on the test set,thereby providing effective technical support for online monitoring of submodule capacitor aging.
文摘Reconfiguration,as well as optimal utilization of distributed generation sources and capacitor banks,are highly effective methods for reducing losses and improving the voltage profile,or in other words,the power quality in the power distribution system.Researchers have considered the use of distributed generation resources in recent years.There are numerous advantages to utilizing these resources,the most significant of which are the reduction of network losses and enhancement of voltage stability.Non-dominated Sorting Genetic Algorithm II(NSGA-II),Multi-Objective Particle Swarm Optimization(MOPSO),and Intersect Mutation Differential Evolution(IMDE)algorithms are used in this paper to perform optimal reconfiguration,simultaneous location,and capacity determination of distributed generation resources and capacitor banks.Three scenarios were used to replicate the studies.The reconfiguration of the switches,as well as the location and determination of the capacitor bank’s optimal capacity,were investigated in this scenario.However,in the third scenario,reconfiguration,and determining the location and capacity of the Distributed Generation(DG)resources and capacitor banks have been carried out simultaneously.Finally,the simulation results of these three algorithms are compared.The results indicate that the proposed NSGAII algorithm outperformed the other two multi-objective algorithms and was capable of maintaining smaller objective functions in all scenarios.Specifically,the energy losses were reduced from 211 to 51.35 kW(a 75.66%reduction),119.13 kW(a 43.54%reduction),and 23.13 kW(an 89.04%reduction),while the voltage stability index(VSI)decreased from 6.96 to 2.105,1.239,and 1.257,respectively,demonstrating significant improvement in the voltage profile.
基金National Natural Science Foundation of China (No. 22179123)Taishan Scholar Program of Shandong Province,China (No. tsqn202211048)Fundamental Research Funds for the Central Universities (No.202262010)。
文摘Zinc-ion hybrid capacitors (ZIHCs) have received increasing attention as energy storage devices owing to their low cost,high safety,and environmental friendliness.However,their progress has been hampered by low energy and power density,as well as unsatisfactory long-cycle stability,mainly due to the lack of suitable electrode materials.In this context,we have developed manganese single atoms implanted in nitrogen-doped porous carbon nanosheets (MnSAs/NCNs) using a metal salt template method as cathodes for ZIHCs.The metal salt serves a dual purpose in the synthesis process:It facilitates the uniform dispersion of Mn atoms within the carbon matrix and acts as an activating agent to create the porous structure.When applied in ZIHCs,the MnSAs/NCNs electrode demonstrates exceptional performance,including a high capacity of 203 m Ah g^(-1),an energy density of 138 Wh kg^(-1)at 68 W kg^(-1),and excellent cycle stability with 91%retention over 10,000 cycles.Theoretical calculations indicate that the introduced Mn atoms modulate the local charge distribution of carbon materials,thereby improving the electrochemical property.This work demonstrates the significant potential of carbon materials with metal atoms in zinc-ion hybrid capacitors,not only in enhancing electrochemical performance but also in providing new insights and methods for developing high-performance energy storage devices.
基金support from National Natural Science Foundation of China(22109056,22409075)Marine Equipment and Technology Institute,Jiangsu University of Science and Technology(XTCX202405)。
文摘Zinc-ion capacitors have gained significant interest because of the exceptional capacity of zinc,the safety of aqueous electrolytes,and the low cost of carbon materials.However,the low capacity of carbon materials greatly limits the energy density of the capacitors.Structural modification or introduction of heteroatom doping to carbon materials sacrifices their volumetric density and cycling stability.Here,we introduce soluble methylene blue(MB)into the electrolyte of the carbon electrode to enhance the capacity by utilizing its redox reactions at the interface.Adding MB increases the electrode capacity to118 m A·h·g^(-1),3.8 times higher compared to that without MB.Importantly,AC electrode with MB delivers an ultrahigh cycling stability with a retention of 90%after 12000 cycles.In situ and ex situ characterization indicates that MB undergoes reversible structural changes during the processes.Theoretical calculations further demonstrate that the reaction of MB discharging process involves two electrons and two protons,going through a radical intermediate state.Assembled Zn//AC capacitor with MB achieves a maximum capacity of 137 m A·h·g^(-1),3.4 times higher compared to the capacitor without MB.Additionally,the capacitor with MB exhibits an energy density of 105.8 W·h·kg^(-1),three times higher than that without MB.Moreover,the capacitor exhibits outstanding cycling stability,retaining92%of the capacity even after 8000 cycles.Our results demonstrate that MB can effectively promote the energy density of the capacitor without sacrificing its cycling stability.
基金supported by the National Natural Science Foundation of China(22408061 and 22468005)Program for Introducing High-Level Talents from Guangxi University,and Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(2023Z014).
文摘Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Efficient potassium activation is the key to develop high-performance oxygen-rich porous carbon cathodes.Herein,the alkali lignin,extracted from eucalyptus wood by geopolymer-assisted low-alkali pretreatment,is used to prepare oxygen-rich lignin-derived porous carbons(OLPCs)through KOH activation and K_(2)CO_(3)activation at 700-900℃.KOH activation constructs a hierarchical micro-mesoporous structure,while K_(2)CO_(3)activation constructs a microporous structure.Furthermore,K_(2)CO_(3)activation could more efficiently construct active oxygen(C=O)species than KOH activation.The OLPCs prepared by KOH/K_(2)CO_(3)activations at 800℃show the highest microporosity(78.4/87.7%)and C=O content(5.3/8.0 at.%).Due to that C=O and micropore adsorb zinc ions,the OLPCs prepared by K_(2)CO_(3)activation at 800℃with higher C=O content and microporosity deliver superior capacitive performance(256 F g^(-1)at 0.1 A g^(-1))than that by KOH activation at 800℃(224 F g^(-1)at 0.1 A g^(-1)),and excellent cycling stability.This work provides a new insight into the sustainable preparation of oxygenrich porous carbon cathodes through efficient potassium activation for ZIHCs.
基金financially supported by the Natural Science Foundation of Xiamen,China(No.3502Z202373070).
文摘Zinc-ion capacitors(ZICs)are promising energy storage devices due to their balance between the energy and power densities inherited from Zn-ion batteries and supercapacitors,respectively.However,the low specific capacitance of carbon cathode materials and the dendrite growth on Zn anode have set fatal drawbacks to their energy density and cycle stability.Herein,we demonstrate that,in 1 M Zn(CF_(3)SO_(3))_(2)/DMF(N,N-dimethylformamide)electrolyte,confining oxygen in carbon cathode materials via high-energy ball milling can synergistically introduce additional pseudocapacitance on the cathode side while suppressing the dendrite growth on Zn anode side,which jointly lead to high energy density(94 Wh kg^(−1)at 448 W kg^(−1))and long cycle stability of ZICs.The hydroxyl group in carbon cathode can be transformed to C–O–Zn together with the release of protons during the initial discharge,which in turn stimulates the defluorination of CF_(3)SO_(3)^(-)anions and formation of ZnF_(2)on both cathode and anode.The ZnF2 formed on the surface of the Zn anode suppresses the dendrite growth by regulating the Zn^(2+)deposition/stripping in a reticular structure,resulting in the excellent cycle stability.This work provides a facile strategy to rationally design and construct high energy and stable ZICs through engineering the oxygen-bearing functional groups in carbon cathode materials.
基金financially supported by the Applied Basic Research Project of Qinghai Province(No.2024-ZJ-766)the Youth Innovation Promotion Association CAS(No.2018466)
文摘Developing high-performance anode materials is crucial for the advancement of sodium-ion capacitors with high-energy density and large power density.Bimetallic oxides exhibit a high specific capacity due to their synergistic effects in electrochemical processes.However,challenges such as poor electrical conductivity,slow ion transport,and volume expansion severely limit their development.In this study,Co_(2)VO_(4)@C-1.5 was synthesized through a straightforward method involving solvent-heating and carbonization via calcination.The synergistic effect of Co and V,mitigation of volume expansion by the carbon-coated layer,enhancement of pseudocapacitive behavior and improved electrical conductivity of Co_(2)VO_(4)@C-1.5 contribute to its superior electrochemical performance.The specific capacity of Co_(2)VO_(4)@C-1.5 remained steady at 288.8 and 171.7 mAh g^(-1)after 100 and 500 cycles at 100 and 1000 mA g^(-1),respectively.Density functional theory(DFT)calculations show a notable reduction in the energy barrier of Co_(2)VO_(4)@C-1.5.Furthermore,the assembled sodium-ion capacitor Co_(2)VO_(4)@C-1.5//AC demonstrates high-energy density(108.5 Wh kg^(-1)at 99.8 W kg^(-1)),remarkable power density(38.2 Wh kg^(-1)at 12,000 W kg^(-1)),and longcycle stability(capacity retention of 80.6%after 6000 cycles).The design and optimization of the carbon-coated structure provide valuable insights for the development of bimetallic oxide materials in sodium-ion capacitors(SICs).
基金support from the National Natural Science Foundation of China(Grant No.U22A20145,51904115,52072151,52171211,52102253,and 52271218)Jinan Independent Innovative Team(2020GXRC015)Major Program of Shandong Province Natural Science Foundation(ZR2023ZD43,ZR2021ZD05).
文摘Low specific capacitances and/or limited working potential(≤4.5 V).of the prevalent carbon-based positive electrodes as the inborn bottleneck seriously hinder practical advancement of lithium-ion capacitors.Thus,breakthroughs in enhancement of both specific capacitances and upper cutoff potentials are enormously significant for high-energy density lithium-ion capacitors.Herein,we first meticulously design and scalably fabricate a commercializable fluorine-doped porous carbon material with competitive tap density,large active surface,appropriate aperture distribution,and promoted affinity with the electrolyte,rendering its abundant electroactive inter-/surface and rapid PF_(6)^(-)transport.Theoretical calculations authenticate that fluorine-doped porous carbon possesses lower PF_(6)^(-)adsorption energy and stronger interaction with PF_(6)^(-).Thanks to the remarkable structural/compositional superiority,when served as a positive electrode toward lithium-ion capacitors,the commercial-level fluorine-doped porous carbon showcases the record-breaking electrochemical properties within a wider working window of 2.5-5.0 V(vs Li/Li^(+))in terms of high-rate specific capacitances and long-duration stability,much superior to commercial activated carbon.More significantly,the 4.5 V-class graphite//fluorine-doped porous carbon lithium-ion capacitors are first constructed and manifest competitive electrochemical behaviors with long-cycle life,modest polarization,and large energy density.Our work provides a commendable positive paradigm and contributes a major step forward in next-generation lithium-ion capacitors and even other high-energy density metal-ion capacitors.
基金Natural Science Foundation of Xinjiang Uygur Autonomous Region,Grant/Award Number:2023D01C11National Natural Science Foundation of China,Grant/Award Numbers:22369019,U2003216+2 种基金Special Projects on Regional Collaborative Innovation-SCO Science and Technology Partnership Program,International Science and Technology Cooperation Program,Grant/Award Number:2022E01020Tianshan Talent Training Program,Grant/Award Number:2023TSYCLJ0019National Key Research and Development Program of China,Grant/Award Numbers:2022YFB4101600,2022YFB4101601。
文摘The rise of Zn-ion hybrid capacitor(ZHC)has imposed high requirements on carbon cathodes,including reasonable configuration,high specific surface area,multiscale pores,and abundant defects.To achieve this objective,a template-oriented strategy coupled with multi-heteroatom modification is proposed to precisely synthesize a three-dimensional boron/nitrogen-rich carbon nanoflake-interconnected micro/nano superstructure,referred to as BNPC.The hierarchically porous framework of BNPC shares short channels for fast Zn2+transport,increased adsorption-site accessibility,and structural robustness.Additionally,the boron/nitrogen incorporation effect significantly augments Zn2+adsorption capability and more distinctive pseudocapacitive nature,notably enhancing Zn-ion storage and transmission kinetics by performing the dual-storage mechanism of the electric double-layer capacitance and Faradaic redox process in BNPC cathode.These merits contribute to a high capacity(143.7 mAh g^(-1)at 0.2 A g^(-1))and excellent rate capability(84.5 mAh g^(-1)at 30 A g^(-1))of BNPC-based aqueous ZHC,and the ZHC still shows an ultrahigh capacity of 108.5 mAh g^(-1)even under a high BNPC mass loading of 12 mg cm^(-2).More critically,the BNPC-based flexible device also sustains notable cyclability over 30,000 cycles and low-rate self-discharge of 2.13 mV h-1 along with a preeminent energy output of 117.15 Wh kg^(-1)at a power density of 163.15Wkg^(-1),favoring a creditable applicability in modern electronics.In/ex-situ analysis and theoretical calculations elaborately elucidate the enhanced charge storage mechanism in depth.The findings offer a promising platform for the development of advanced carbon cathodes and corresponding electrochemical devices.
基金the financial support from the National Natural Science Foundation of China(No.52225208 and 51802131)the Training Program for academic and technical leaders in major disciplines of Jiangxi Province-Young Talents(No.20212BCJ23021)the Natural Science Foundation of Jiangxi Province,China(No.20232BAB204020).
文摘1T-MoS_(2)nanosheets,with metallic conductivity and high capacity,hold great potential for lithium-ion capacitors(LICs),but suffer from sluggish reaction kinetics due to dense stacking.Herein,1T-MoS_(2)nanosheets with enlarged interlayer spacing,vertically bonded to reduced graphene oxide(rGO)(1T-MoS_(2)/rGO),were designed using a hydrothermal-assisted dispersion and intercalation strategy.The active nitrogen species derived from N,N-dimethylformamide(DMF)not only bridge the rGO and MoS_(2)through strong Mo-N-C bonds to promote the formation of dispersed MoS_(2)nanosheets,but also intercalate into the MoS_(2)structure,further enlarging the interlayer spacing.This unique structure synergistically enhances meso-and microscale mass transfer outside and inside of the few-layered nanosheets,significantly improving electrochemical reaction kinetics and reducing the kinetic mismatch between the anode and cathode.Consequently,the resulting 1T-MoS_(2)/rGO achieves a capacity of 500 mAh g^(-1)after 500 cycles at 5 A g^(-1)and a high rate performance of 587 mAh g^(-1)at a high rate of 10 A g^(-1).Moreover,the assembled 3D vertical 1T-MoS_(2)/rGO//AC LIC delivers a high energy density of 100.3 Wh kg^(-1)at a power density of1.0 kW kg^(-1),and long cycle stability with capacity retention as high as 91.02%after 5000 cycles at 2 A g^(-1).This work provides a generalizable strategy for engineering two-dimensional material-based electrodes,offering new insights into high-performance energy storage systems.
