Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C...Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2＋ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA-h/g at 10C rate show good capacity retention capability （75% of their initial capacity after 800 cycles at 10C rate）. The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.展开更多
Due to the abundant sodium reserves and high safety,sodium ion batteries(SIBs)are foreseen a promising future.While,hard carbon materials are very suitable for the anode of SIBs owing to their structure and cost advan...Due to the abundant sodium reserves and high safety,sodium ion batteries(SIBs)are foreseen a promising future.While,hard carbon materials are very suitable for the anode of SIBs owing to their structure and cost advantages.However,the unsatisfactory initial coulombic efficiency(ICE)is one of the crucial blemishes of hard carbon materials and the slow sodium storage kinetics also hinders their wide application.Herein,with spherical nano SiO_(2)as pore-forming agent,gelatin and polytetrafluoroethylene as carbon sources,a multi-porous carbon(MPC)material can be easily obtained via a co-pyrolysis method,by which carbonization and template removal can be achieved synchronously without the assistance of strong acids or strong bases.As a result,the MPC anode exhibited remarkable ICE of 83%and a high rate capability(208 m Ah/g at 5 A/g)when used in sodium-ion half cells.Additionally,coupling with Na3V2(PO4)3as the cathode to assemble full cells,the as-fabricated MPC//NVP full cell delivered a good rate capability(146 m Ah/g at 5 A/g)as well,implying a good application prospect the MPC anode has.展开更多
LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron micr...LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron microscopy (TEM),energy dispersive spectroscopy (EDS),charge-discharge cycling,cyclic voltammetry (CV),and electrochemical impedance spectroscopy (EIS).Uniform coated layer with a thickness of about 3 nm was observed on the surface of LiNi1/3Co1/3Mn1/3O2 particle by TEM.At 0.5C and 2C rates,1.5% (mass fraction) AlF3-coated LiNi1/3Co1/3Mn1/3O2/Li in 2.8-4.3 V versus Li/Li+ after 80 cycles showed less than 3% of capacity fading,while those of the bare one were 16.5% and 45.9%,respectively.At 5C rate,the capacity retention of the coated sample after 50 cycles maintained 91.4% of the initial discharge capacity,while that of the bare one decreased to 52.6%.EIS result showed that a little change of charge transfer resistance of the coated sample resulting from uniform thin AlF3 layer was proposed as the main reason why its rate capability was improved obviously.CV result further indicated a greater reversibility for the electrode processes and better electrochemical performance of AlF3-coated layer.展开更多
In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vert...In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^(-2) and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^(-2) but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^(-2);the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^(-2)(246.9 mAh g^(-1)) at 3 mA cm^(-2) and outstanding rate performance with 84.7% retention at 30 mA cm^(-2),suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^(-2) at the power density of 2.14 mW cm^(-2) with excellent electrochemical cycling stability.展开更多
Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density an...Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.展开更多
MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable inte...MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.展开更多
The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve th...The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve the high rate capability of Co_(3)O_(4)nanowire array electrodes by uniformly loading Ag nanoparticles onto the surfaces of the Co_(3)O_(4)nanowires via the silver-mirror reaction.The highly electrically conductive silver nanoparticles function as a network for the facile transport of electrons between the current collectors(Ti substrates)and the Co_(3)O_(4)active materials.High capacity as well as remarkable rate capability has been achieved through this simple approach.Such novel Co_(3)O_(4)-Ag composite nanowire array electrodes have great potential for practical applications in pseudo-type supercapacitors as well as in lithium ion batteries.展开更多
The flexible transparent supercapacitors have been considered as one of the key energy-storage components to power the smart portable electronic devices.However,it is still a challenge to explore flexible transparent ...The flexible transparent supercapacitors have been considered as one of the key energy-storage components to power the smart portable electronic devices.However,it is still a challenge to explore flexible transparent capacitive electrodes with high rate capability.Herein,conductive Ni3(HITP)2(HITP=2,3,6,7,10,11-hexaiminotriphenylene)thin films are adopted as capacitive electrodes in flexible transparent supercapacitors.The Ni3(HITP)2 electrode possesses the excellent optoelectronic property with optical transmittance(T)of 78.4%and sheet resistance(Rs)of 51.3Ωsq-1,remarkable areal capacitance(CA)of 1.63 mF cm^-2and highest scan rate up to 5000 mV s-1.The asymmetric Ni3(HITP)2//PEDOT:PSS supercapacitor(T=61%)yields a high CA of 1.06 mF cm^-2at 3μA cm-2,which maintains 77.4%as the current density increases by 50 folds.The remarkable rate capability is ascribed to the collaborative advantages of low diffusion resistance and high ion accessibility,resulting from the intrinsic conductivity,short oriented pores and large specific areas of Ni3(HITP)2 films.展开更多
High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through ...High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through a facile and cost-effective self-assembly of.one-dimensional(10)PANI nanofibers and two-dimensional(20)Ti3C2Tx nanosheets.PANl!Ti3C2Tx delivers greatly improved specific capacitance,ultrahigh rate capability(67%capacitance retention from 1 to 100 A·g^(-1))as well as good cycle stability.Electrochemical kinetic analysis reveals that PANI/Ti3C2Tx is featured with surface capacitance-dominated process and has a quasi-reversible kinetics at high scan rates,giving rise to an ultrahigh rate capability.By using PANl!Ti3C2Tx as positive electrode,an 1.8 V aqueous asymmetric supercapacitor(ASC)is successfully assembled,showing a maximum energy density of 50.8 Wh·kg^(-1)·(at 0.9 kW-kg-1)and a power density of 18 kW·kg^(-1)(at 26 Wh·kg^(-1)).Moreover,an 3.0 V organic ASC is also elaborately fabricated,·by using PANI/Ti3C2Tx,achieving an ultrahigh energy density of 67.2 Wh·kg^(-1)(at 1.5 kW·kg^(-1))and a power density of 30 kW·kg^(-1)·(at 26.8 Wh·kg^(-1)).The present work not only improves fundamental understanding of the structure-property relationship towards ultrahigh rate capability electrode materials,but also provides valuable guideline for the rational design of high-performance:energy storage devices with both high energy and power densities.展开更多
In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for as...In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.展开更多
An effective method is designed to construct three-dimensional(3D)Nb_(2)C/reduced graphene oxide(rGO)hybrid aerogels through a low-temperature graphene oxide(GO)-assisted hydrothermal self-assembly followed by freeze-...An effective method is designed to construct three-dimensional(3D)Nb_(2)C/reduced graphene oxide(rGO)hybrid aerogels through a low-temperature graphene oxide(GO)-assisted hydrothermal self-assembly followed by freeze-drying and annealing.The intimately coupled Nb_(2)C/rGO hybrid aerogel combines the advantages of large specific surface area and rich 3D interconnected porous structure of aerogel as well as high conductivity and low potassium diffusion energy barrier of Nb_(2)C,which not only effectively prevents the self-restacking of Nb2C nanosheets to allow more active sites exposed and accommodate the volume change during the charge/discharge process,but also increases the accessibility of electrolyte and promotes the rapid transfer of ions/electrons.As a result,Nb_(2)C/rGO-2 as the anode of potassium ion batteries(KIBs)delivers a large reversible specific capacity(301.7 mAh·g^(−1)after 500 cycles at 2.0 A·g^(−1)),an ultrahigh rate capability(155.5 mAh·g^(−1)at 20 A·g^(−1)),and an excellent long-term large-current cycle stability(198.8 mAh·g^(−1)after 1,000 cycles at 10 A·g^(−1),with a retention of 83.3%).Such a high-level electrochemical performance,especially the ultrahigh rate capability,is the best among transition metal carbides and nitride(MXene)-based materials reported so far for KIBs.The diffusion kinetics of K+is investigated thoroughly,and the synergetic charge–discharge mechanism and the structure–performance relationship of Nb_(2)C/rGO are revealed explicitly.The present work provides a good strategy to solve the self-restacking problem of two-dimensional materials and also enlarges the potential applications of MXenes.展开更多
The massive application of single crystal(SC)ternary cathode material LiNi_(1-x-y)Mn_(x)Co_(y)O_(2)is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+diffusion and structura...The massive application of single crystal(SC)ternary cathode material LiNi_(1-x-y)Mn_(x)Co_(y)O_(2)is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+diffusion and structural instability.Herein,Pr^(3+),a large radius ion is introduced to single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)to enhance Li^(+)conductivity and structural stability.With 0.4%Pr doping,the Li(Ni_(0.5)Mn_(0.3)Co_(0.2))_(0.996)Pr_(0.004)O_(2)cathode displays a capacity retention of 79.72%at 10 C,and a 98.17%capacity retention after 50 cycles at 25°C and 96.3%capacity retention after 50 cycles at 55°C within a 3.0–4.5 V voltage window.Electrochemical impedance spectroscopy confirms that the Pr doping can effectively lower the charge-transfer resistance and facilitate the transportation of Li^(+)on the surface of LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2).The Direct current internal resistance result implies that the structure of the Pr-doped cathode particles is more stable during cycling.In addition,differential scanning calorimetry measurements measurement combined with in situ X-ray diffraction confirms the thermo-stabilization effect of the Pr dopant.展开更多
Surface modification of graphite anode with electroactive matters has been proven of a more practical strategy in enhancing the performance of Li-ion batteries than exploring alternative novel anode materials.Herein,r...Surface modification of graphite anode with electroactive matters has been proven of a more practical strategy in enhancing the performance of Li-ion batteries than exploring alternative novel anode materials.Herein,rutile TiNbO_(4-x) nanoparticles with a tunnel structure are employed as multifunctional decoration substances in combination with a carbon coating layer to improve the rate and cycle properties of mesocarbon microbeads(MCMBs).As compared to pristine MCMB,the Li^(+)diffusion coefficients of the composite anodes are enhanced due to the synergistic effect of TiNbO_(4-x)@C.Meanwhile,the overcharge and voltage polarization of the composite anodes at high rate are obviously minimized due to the current sharing effect of the high-potential TiNbO_(4-x).Moreover,the amorphous Li_(y)TiNbO_(4-x) converted from TiNbO_(4-x) in the initial lithiation process can deliver pseudocapacitive capacity to the composite anodes from the second cycle.All of these functions of TiNbO_(4-x)@Ccoating layer have directly contributed to the improved rate and cycle performance of the MCMB/TiNbO_(4-x)@C composite anodes.The one containing 12.0 wt%TiNbO_(4-x) exhibits a high reversible specific capacity of 118 m Ah·g^(-1)at 10C(1C=372 m A·g^(-1)),together with a high capacity retention of 90.9%after 300 cycles at 3C,which are all much superior to those of pristine MCMB.展开更多
MXene is a promising energy storage material for miniaturized microbatteries and microsupercapacitors(MSCs).Despite its superior electrochemical performance,only a few studies have reported MXene-based ultrahigh-rate(...MXene is a promising energy storage material for miniaturized microbatteries and microsupercapacitors(MSCs).Despite its superior electrochemical performance,only a few studies have reported MXene-based ultrahigh-rate(>1000 mV s^(−1))on-paper MSCs,mainly due to the reduced electrical conductance of MXene films deposited on paper.Herein,ultrahigh-rate metal-free on-paper MSCs based on heterogeneous MXene/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)-stack electrodes are fabricated through the combination of direct ink writing and femtosecond laser scribing.With a footprint area of only 20 mm^(2),the on-paper MSCs exhibit excellent high-rate capacitive behavior with an areal capacitance of 5.7 mF cm^(−2)and long cycle life(>95%capacitance retention after 10,000 cycles)at a high scan rate of 1000 mV s^(−1),outperforming most of the present on-paper MSCs.Furthermore,the heterogeneous MXene/PEDOT:PSS electrodes can interconnect individual MSCs into metal-free on-paper MSC arrays,which can also be simultaneously charged/discharged at 1000 mV s^(−1),showing scalable capacitive performance.The heterogeneous MXene/PEDOT:PSS stacks are a promising electrode structure for on-paper MSCs to serve as ultrafast miniaturized energy storage components for emerging paper electronics.展开更多
Synthesis of the spinel structure lithium manganese oxide （LiMn2O4） by supercritical hydrothermal （SH） accelerated solid state reaction （SSR） route was studied. The impacts of the reaction pressure, reaction tem...Synthesis of the spinel structure lithium manganese oxide （LiMn2O4） by supercritical hydrothermal （SH） accelerated solid state reaction （SSR） route was studied. The impacts of the reaction pressure, reaction temperature and reaction time of SH route, and the calcination temperature of SSR route on the purity, particle morphology and electrochemical properties of the prepared LiMn2O4 materials were studied. The experimental results show that after 15 min reaction in SH route at 400 ℃ and 30 MPa, the reaction time of SSR could be significantly decreased, e.g. down to 3 h with the formation temperature of 800 ℃, compared with the conventional solid state reaction method. The prepared LiMn2O4 material exhibits good crystallinity, uniform size distribution and good electrochemical performance, and has an initial specific capacity of 120 mA.h/g at a rate of 0.1C （1C=148 mA/g） and a good rate capability at high rates, even up to 50C.展开更多
Layered sodium trititanate(Na_(2)Ti_(3)O_(7),NTO)is a promising anode material for sodium-ion batteries(NIBs)for large-scale energy storage applications because of its relatively low charge potential and low cost.Howe...Layered sodium trititanate(Na_(2)Ti_(3)O_(7),NTO)is a promising anode material for sodium-ion batteries(NIBs)for large-scale energy storage applications because of its relatively low charge potential and low cost.However,NTO suffers from unsatisfactory structural stability against cycling and poor electron conductivity.Herein,an isovalent doping strategy using Sn^(4+)to partially replace Ti^(4+)is demonstrated for improving the cycling stability and rate capability of NTO.The isovalent doping of Sn^(4+)does not alter the valence state of Ti^(4+),thus maintaining the lattice integrality and structural stability.Moreover,the Sn^(4+)dopant creates more Na^(+)-preferable travel channels and expands the interlayer spacing,thus increasing Na^(+)diffusivity.As a result,a Sn^(4+)-doped Na_(2)Ti_(3)O_7(NSTO)electrode exhibits a reversible Na^(+)storage specific capacity of 176 mA h g^(-1)at 0.1C and an ultra-long cycling life with 80.2%capacity retention after5000 cycles at 1C,far outperforming the undoped and aliovalent-doping NTO electrodes reported in the literature.In addition,the NSTO electrode delivers a rate capability of 102 mA h g^(-1)at 5C,higher than that of the NTO electrode(62 mA h g^(-1)).In situ X-ray diffraction characterization results reveal that Na^(+)storage in NSTO undergoes a partial solid-solution reaction mechanism,which is completely different from the two-phase transition mechanism of NTO.Density functional theory calculation results demonstrate that Sn^(4+)doping strengthens the Ti-O bond,contributing to structural stability.This work provides a robust approach to significantly improving the electrochemical performance of NTO-based anode materials for developing long-life NIBs.展开更多
Cubic phase cobalt disulfide(CoS_(2))is recognized as a potential negative material for sodium-ion batteries(SIBs)because of its low band gap,simple synthesis process,and high capacity.Nonetheless,the challenges of sl...Cubic phase cobalt disulfide(CoS_(2))is recognized as a potential negative material for sodium-ion batteries(SIBs)because of its low band gap,simple synthesis process,and high capacity.Nonetheless,the challenges of slow ion diffusion and substantial volume change during cycling,resulting in inadequate rate and cycling performances,remain unresolved.Here,a porous structure is fabricated by etching electrospun carbon nanofibers,subsequently facilitating the growth of CoS_(2)nanoparticles at the pore locations.A nitrogen-doped carbon layer is then applied to the surface to buffer the volumetric expansion effect of CoS_(2).The findings indicate that the carbon nanofibers establish a stable conductive network,while the porous architecture of the carbon fibers,in conjunction with the carbon coating,efficiently mitigates volumetric expansion.Furthermore,density functional theory(DFT)studies show the presence of an interlayer van der Waals force between the sulfur atoms in CoS_(2)and the carbon atoms,which reduces the band gap,enhances the conductivity of the structure,and lowers the energy barrier of Na^(+)migration.The as-prepared anode achieves a reversible capacity of 302.6 mAh g^(-1)at 3.2 A g^(-1)and maintains a capacity of 384.6 mAh g^(-1)at 1.0 A g^(-1)over 800 cycles,demonstrating exceptional rate performance and improved cycling stability.This work shows that the combination of hierarchical porous architecture and a unique electronic structure offers valuable insights for designing high-performance negative materials for SIB s.展开更多
Na_(2)FePO_(4)F is a promising sodium ion cathode due to its low cost,non-toxicity,and high stability.However,the sluggish Na^(+)diffusion kinetics and limited intrinsic electronic conductivity critically restrict its...Na_(2)FePO_(4)F is a promising sodium ion cathode due to its low cost,non-toxicity,and high stability.However,the sluggish Na^(+)diffusion kinetics and limited intrinsic electronic conductivity critically restrict its worldwide application.Herein,an anion-substitution strategy is proposed with SiO_(4)^(4-)as the dopant.SiO_(4)^(4-)substitution for PO_(4)^(3-)can apparently alter the localized electronic density and structural configuration in the lattice of Na_(2)FePO_(4)F,effectively elevating the charge transfer efficiency.As a result,the electrochemical reaction kinetics of Na_(2)FePO_(4)F is significantly enhanced,which is well demonstrated by a series of electrochemical characterizations.As-obtained Na_(2.2)Fe(PO_(4))_(0.8)(SiO_(4))_(0.2)F renders a specific capacity of 84.9 m A h g^(-1)within the region of 2.5-4.0 V at 60 mA g^(-1)(0.5 C),good rate capability,and a capacity retention of 70.0% after 1000 cycles at 1.24 A g^(-1)(10 C).Furthermore,the stabilities of the cathode-electrolyte interface and structure are strengthened,which are verified by in situ EIS and ex situ XRD analysis.These findings highlight silicate anion substitution as a promising and cost-effective strategy for overcoming the limitations of Na_(2)FePO_(4)F,contributing to the development of sustainable energy storage solutions.展开更多
Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies...Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies have shown that constructing heterostructures are considered an effective strategy to solve the hysteresis problem of electronic and ion dynamics in sodiumion battery anode materials.Herein,a nickel-cobalt bimetallic coordination polymer(NiCoCP)was synthesized using a coprecipitation method,and a CoSe_(2)@NiSe_(2) cross-stacked structure was obtained through high-temperature carbonization and selenization processes.CoSe_(2)@NiSe_(2) has a unique heterostructure and carbon film,which synergistically increases a large number of adsorption sites and alleviates the diffusion energy barrier,thereby improving the rapid diffusion kinetics of Na^(+)ions.It has superior rate performance and long-lasting cycle life.For sodium-ion batteries(SIBs),the specific capacity of CoSe_(2)@NiSe_(2) is around 460 mA h g^(-1) after 400 cycles at 1.0 A g^(-1).For potassium-ion batteries(PIBs),CoSe_(2)@NiSe_(2) also exhibits excellent cycling stability,maintaining a specific capacity of 160 mA h g^(-1) after 700 cycles at 1.0 A g^(-1).This study provides a new way to prepare metal selenide heterostructure as the promising anode material for SIBs.展开更多
As promising anodes for sodium-ion batteries,metal sulfides ubiquitously suffer from low-rate and high-plateau issues,greatly hindering their application in full-cells.Herein,exemplifying carbon nanotubes(CNTs)-string...As promising anodes for sodium-ion batteries,metal sulfides ubiquitously suffer from low-rate and high-plateau issues,greatly hindering their application in full-cells.Herein,exemplifying carbon nanotubes(CNTs)-stringed metal sulfides superstructure(CSC)assembled by nano-dispersed SnS_(2) and CoS_(2) phases,cocktail mediation effect similar to that of high-entropy materials is initially studied in ether-based electrolyte to solve the challenges.The high nano-dispersity of metal sulfides in CSC anode underlies the cocktail-like mediation effect,enabling the circumvention of intrinsic drawbacks of different metal sulfides.By utilizing ether-based electrolyte,the reversibility of metal sulfides is greatly improved,sustaining a long-life effectivity of cocktail-like mediation.As such,CSC effectively overcomes low-rate flaw of SnS_(2) and highplateau demerit of CoS_(2),simultaneously realizes a high rate and a low plateau.In half-cells,CSC delivers an ultrahigh-rate capability of 327.6 mAh g^(−1) anode at 20 A g^(−1),far outperforming those of monometallic sulfides(SnS_(2),CoS_(2))and their mixtures.Compared with CoS_(2) phase and SnS_(2)/CoS_(2) mixture,CSC shows remarkably lowered average charge voltage up to ca.0.62 V.As-assembled CSC//Na1.5VPO4.8F0.7 full-cell shows a good rate capability(0.05~1.0 A g^(−1),120.3 mAh g^(−1) electrode at 0.05 A g^(−1))and a high average discharge voltage up to 2.57 V,comparable to full-cells with alloy-type anodes.Kinetics analysis verifies that the cocktail-like mediation effect largely boosts the charge transfer and ionic diffusion in CSC,compared with single phase and mixed phases.Further mechanism study reveals that alternative and complementary electrochemical processes between nano-dispersed SnS_(2) and CoS_(2) phases are responsible for the lowered charge voltage of CSC.This electrolyte/structure-dependent cocktail-like mediation effect effectively enhances the practicability of metal sulfide anodes,which will boost the development of high-rate/-voltage sodium-ion full batteries.展开更多
基金Project(2011M501090) upported by the China Postdoctoral Science FoundationProject(SCUT2012ZZ0042) upported by the Fundamental Research Funds for the Central Universities+1 种基金Project supported by the"SPR-2011"of South China University of TechnologyProject(NRC07/08.EG01)supprted by the Fok Ying Tung Foundation
文摘Spinel LiMn2O4 microspheres with durable high rate capability were synthesized by a facile route using spherical MnCO3 precursors as the self-supported templates, combined with the calcinations of LiNO3 at 700 °C for 8 h. The spherical MnCO3 precursors were obtained from the control of the crystallizing process of Mn2＋ ions and NH4HCO3 in aqueous solution. The effects of the mole ratio of the raw materials, reaction time, and reaction temperature on the morphology and yield of the MnCO3 were investigated. The as-synthesized MnCO3 and LiMn2O4 microspheres were characterized by powder X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Galvanostatic charge/discharge tests indicate that the spinel LiMn2O4 microspheres deliver a discharge capacity of 90 mA-h/g at 10C rate show good capacity retention capability （75% of their initial capacity after 800 cycles at 10C rate）. The durable high rate capability suggests that the as-synthesized LiMn2O4 microspheres are promising cathode materials for high power lithium ion batteries.
基金financially supported by the Start-up Funding of Jinan University(No.88016105)the Discipline Construction Outstanding Young Backbone Project(No.12819023)+3 种基金the Fundamental Research Funds for the Central Universities(No.21620317)the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110611 and 2021A1515010362)the Guangzhou Basic and Applied Basic Research Foundation(No.202102020995)supported by the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(No.2020B121201005)。
文摘Due to the abundant sodium reserves and high safety,sodium ion batteries(SIBs)are foreseen a promising future.While,hard carbon materials are very suitable for the anode of SIBs owing to their structure and cost advantages.However,the unsatisfactory initial coulombic efficiency(ICE)is one of the crucial blemishes of hard carbon materials and the slow sodium storage kinetics also hinders their wide application.Herein,with spherical nano SiO_(2)as pore-forming agent,gelatin and polytetrafluoroethylene as carbon sources,a multi-porous carbon(MPC)material can be easily obtained via a co-pyrolysis method,by which carbonization and template removal can be achieved synchronously without the assistance of strong acids or strong bases.As a result,the MPC anode exhibited remarkable ICE of 83%and a high rate capability(208 m Ah/g at 5 A/g)when used in sodium-ion half cells.Additionally,coupling with Na3V2(PO4)3as the cathode to assemble full cells,the as-fabricated MPC//NVP full cell delivered a good rate capability(146 m Ah/g at 5 A/g)as well,implying a good application prospect the MPC anode has.
基金Project(50542004) supported by the National Natural Science Foundation of ChinaProject(1960-71131100017) supported by Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron microscopy (TEM),energy dispersive spectroscopy (EDS),charge-discharge cycling,cyclic voltammetry (CV),and electrochemical impedance spectroscopy (EIS).Uniform coated layer with a thickness of about 3 nm was observed on the surface of LiNi1/3Co1/3Mn1/3O2 particle by TEM.At 0.5C and 2C rates,1.5% (mass fraction) AlF3-coated LiNi1/3Co1/3Mn1/3O2/Li in 2.8-4.3 V versus Li/Li+ after 80 cycles showed less than 3% of capacity fading,while those of the bare one were 16.5% and 45.9%,respectively.At 5C rate,the capacity retention of the coated sample after 50 cycles maintained 91.4% of the initial discharge capacity,while that of the bare one decreased to 52.6%.EIS result showed that a little change of charge transfer resistance of the coated sample resulting from uniform thin AlF3 layer was proposed as the main reason why its rate capability was improved obviously.CV result further indicated a greater reversibility for the electrode processes and better electrochemical performance of AlF3-coated layer.
基金supported by the National Natural Science Foundation of China (Nos. 21975123, 61704076)the Natural Science Basic Research Program of Shaanxi (No. 2020JM-092)+2 种基金the Natural Science Foundation of Jiangsu Province (No. BK20171018)the Six Talent Peaks Project in Jiangsu Province (No. XCL-024)the Fundamental Research Funds for the Central Universities。
文摘In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^(-2) and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^(-2) but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^(-2);the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^(-2)(246.9 mAh g^(-1)) at 3 mA cm^(-2) and outstanding rate performance with 84.7% retention at 30 mA cm^(-2),suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^(-2) at the power density of 2.14 mW cm^(-2) with excellent electrochemical cycling stability.
基金financially supported by the National Natural Science Foundation of China(52074023)the Beijing Natural Science Foundation(2222062)+1 种基金the National Key R&D Program of China(2018YFB0905600)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-21-023)。
文摘Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.
基金supported by the National Natural Science Foundation of China(No.52062030)the Key Program of the Natural Science Foundation of Gansu Province(23JRRA789)。
文摘MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.
基金This work was jointly supported by the City University of Hong Kong(Project 7002465)the National Natural Science Foundation of China(No.21001117/B0107).
文摘The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve the high rate capability of Co_(3)O_(4)nanowire array electrodes by uniformly loading Ag nanoparticles onto the surfaces of the Co_(3)O_(4)nanowires via the silver-mirror reaction.The highly electrically conductive silver nanoparticles function as a network for the facile transport of electrons between the current collectors(Ti substrates)and the Co_(3)O_(4)active materials.High capacity as well as remarkable rate capability has been achieved through this simple approach.Such novel Co_(3)O_(4)-Ag composite nanowire array electrodes have great potential for practical applications in pseudo-type supercapacitors as well as in lithium ion batteries.
基金supported by the National Natural Science Foundation of China(NSFC)(61804082,21671108,51473078,and 61935017)Synergetic Innovation Center for Organic Electronics and Information Displays and Projects of International Cooperation and Exchanges NSFC(51811530018)+4 种基金the China Postdoctoral Science Foundation funded project(2018M642286)National Program for Support of Top-Notch Young Professionals,Scientific and Technological Innovation Teams of Colleges and Universities in Jiangsu Province(TJ215006)Priority Academic Program Development of Jiangsu Higher Education Institutions(YX03001)Jiangsu Planned Projects for Postdoctoral Research Funds(2019K047A)Science Foundation of Nanjing University of Posts and Telecommunications(NY217142)。
文摘The flexible transparent supercapacitors have been considered as one of the key energy-storage components to power the smart portable electronic devices.However,it is still a challenge to explore flexible transparent capacitive electrodes with high rate capability.Herein,conductive Ni3(HITP)2(HITP=2,3,6,7,10,11-hexaiminotriphenylene)thin films are adopted as capacitive electrodes in flexible transparent supercapacitors.The Ni3(HITP)2 electrode possesses the excellent optoelectronic property with optical transmittance(T)of 78.4%and sheet resistance(Rs)of 51.3Ωsq-1,remarkable areal capacitance(CA)of 1.63 mF cm^-2and highest scan rate up to 5000 mV s-1.The asymmetric Ni3(HITP)2//PEDOT:PSS supercapacitor(T=61%)yields a high CA of 1.06 mF cm^-2at 3μA cm-2,which maintains 77.4%as the current density increases by 50 folds.The remarkable rate capability is ascribed to the collaborative advantages of low diffusion resistance and high ion accessibility,resulting from the intrinsic conductivity,short oriented pores and large specific areas of Ni3(HITP)2 films.
基金support of the National Natural Science Foundation of China(No.21773116)the Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP,20130091110010)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK2011438)the National Science Fund for Talent Training in Basic Science(No.J1103310)the Modern Analysis Center of Nanjing University and the Program B for Outstanding PhD Candidate of Nanjing University.
文摘High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through a facile and cost-effective self-assembly of.one-dimensional(10)PANI nanofibers and two-dimensional(20)Ti3C2Tx nanosheets.PANl!Ti3C2Tx delivers greatly improved specific capacitance,ultrahigh rate capability(67%capacitance retention from 1 to 100 A·g^(-1))as well as good cycle stability.Electrochemical kinetic analysis reveals that PANI/Ti3C2Tx is featured with surface capacitance-dominated process and has a quasi-reversible kinetics at high scan rates,giving rise to an ultrahigh rate capability.By using PANl!Ti3C2Tx as positive electrode,an 1.8 V aqueous asymmetric supercapacitor(ASC)is successfully assembled,showing a maximum energy density of 50.8 Wh·kg^(-1)·(at 0.9 kW-kg-1)and a power density of 18 kW·kg^(-1)(at 26 Wh·kg^(-1)).Moreover,an 3.0 V organic ASC is also elaborately fabricated,·by using PANI/Ti3C2Tx,achieving an ultrahigh energy density of 67.2 Wh·kg^(-1)(at 1.5 kW·kg^(-1))and a power density of 30 kW·kg^(-1)·(at 26.8 Wh·kg^(-1)).The present work not only improves fundamental understanding of the structure-property relationship towards ultrahigh rate capability electrode materials,but also provides valuable guideline for the rational design of high-performance:energy storage devices with both high energy and power densities.
基金supported by the National Natural Science Foundation of China (51672144, 51572137 and 51702181)the Natural Science Foundation of Shandong Province (ZR2017BB013 and ZR2019BEM042)+2 种基金Higher Educational Science and Technology Program of Shandong Province (J17KA014, J18KA001 and J18KA033)Taishan Scholars Program of Shandong Province (ts201511034)Overseas Taishan Scholars Program
文摘In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.
基金the National Natural Science Foundation of China(No.21773116)and Modern Analysis Center of Nanjing University.
文摘An effective method is designed to construct three-dimensional(3D)Nb_(2)C/reduced graphene oxide(rGO)hybrid aerogels through a low-temperature graphene oxide(GO)-assisted hydrothermal self-assembly followed by freeze-drying and annealing.The intimately coupled Nb_(2)C/rGO hybrid aerogel combines the advantages of large specific surface area and rich 3D interconnected porous structure of aerogel as well as high conductivity and low potassium diffusion energy barrier of Nb_(2)C,which not only effectively prevents the self-restacking of Nb2C nanosheets to allow more active sites exposed and accommodate the volume change during the charge/discharge process,but also increases the accessibility of electrolyte and promotes the rapid transfer of ions/electrons.As a result,Nb_(2)C/rGO-2 as the anode of potassium ion batteries(KIBs)delivers a large reversible specific capacity(301.7 mAh·g^(−1)after 500 cycles at 2.0 A·g^(−1)),an ultrahigh rate capability(155.5 mAh·g^(−1)at 20 A·g^(−1)),and an excellent long-term large-current cycle stability(198.8 mAh·g^(−1)after 1,000 cycles at 10 A·g^(−1),with a retention of 83.3%).Such a high-level electrochemical performance,especially the ultrahigh rate capability,is the best among transition metal carbides and nitride(MXene)-based materials reported so far for KIBs.The diffusion kinetics of K+is investigated thoroughly,and the synergetic charge–discharge mechanism and the structure–performance relationship of Nb_(2)C/rGO are revealed explicitly.The present work provides a good strategy to solve the self-restacking problem of two-dimensional materials and also enlarges the potential applications of MXenes.
基金Financial supports from National Natural Science Foundation of China(51872027)Beijing Natural Science Foundation(Z200011)are gratefully acknowledged。
文摘The massive application of single crystal(SC)ternary cathode material LiNi_(1-x-y)Mn_(x)Co_(y)O_(2)is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+diffusion and structural instability.Herein,Pr^(3+),a large radius ion is introduced to single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)to enhance Li^(+)conductivity and structural stability.With 0.4%Pr doping,the Li(Ni_(0.5)Mn_(0.3)Co_(0.2))_(0.996)Pr_(0.004)O_(2)cathode displays a capacity retention of 79.72%at 10 C,and a 98.17%capacity retention after 50 cycles at 25°C and 96.3%capacity retention after 50 cycles at 55°C within a 3.0–4.5 V voltage window.Electrochemical impedance spectroscopy confirms that the Pr doping can effectively lower the charge-transfer resistance and facilitate the transportation of Li^(+)on the surface of LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2).The Direct current internal resistance result implies that the structure of the Pr-doped cathode particles is more stable during cycling.In addition,differential scanning calorimetry measurements measurement combined with in situ X-ray diffraction confirms the thermo-stabilization effect of the Pr dopant.
基金supported by the Natural Science Foundation Project of Fujian Province(Nos.2020J01287 and 2020H0024)。
文摘Surface modification of graphite anode with electroactive matters has been proven of a more practical strategy in enhancing the performance of Li-ion batteries than exploring alternative novel anode materials.Herein,rutile TiNbO_(4-x) nanoparticles with a tunnel structure are employed as multifunctional decoration substances in combination with a carbon coating layer to improve the rate and cycle properties of mesocarbon microbeads(MCMBs).As compared to pristine MCMB,the Li^(+)diffusion coefficients of the composite anodes are enhanced due to the synergistic effect of TiNbO_(4-x)@C.Meanwhile,the overcharge and voltage polarization of the composite anodes at high rate are obviously minimized due to the current sharing effect of the high-potential TiNbO_(4-x).Moreover,the amorphous Li_(y)TiNbO_(4-x) converted from TiNbO_(4-x) in the initial lithiation process can deliver pseudocapacitive capacity to the composite anodes from the second cycle.All of these functions of TiNbO_(4-x)@Ccoating layer have directly contributed to the improved rate and cycle performance of the MCMB/TiNbO_(4-x)@C composite anodes.The one containing 12.0 wt%TiNbO_(4-x) exhibits a high reversible specific capacity of 118 m Ah·g^(-1)at 10C(1C=372 m A·g^(-1)),together with a high capacity retention of 90.9%after 300 cycles at 3C,which are all much superior to those of pristine MCMB.
基金China Scholarship Council,Grant/Award Number:201906230359Vetenskapsrådet,Grant/Award Number:2019-04731+4 种基金HORIZON EUROPE Digital,Industry and Space,Grant/Award Number:101070255Stiftelsen Olle Engkvist Byggmästare,Grant/Award Number:2014/799Swedish National Infrastructure in Advanced Electron Microscopy,Grant/Award Numbers:2021-00171,RIF21-0026KTH Energy Platform,Grant/Award Number:HT2021Swedish Foundation for Strategic Research,Grant/Award Number:STP19-0014。
文摘MXene is a promising energy storage material for miniaturized microbatteries and microsupercapacitors(MSCs).Despite its superior electrochemical performance,only a few studies have reported MXene-based ultrahigh-rate(>1000 mV s^(−1))on-paper MSCs,mainly due to the reduced electrical conductance of MXene films deposited on paper.Herein,ultrahigh-rate metal-free on-paper MSCs based on heterogeneous MXene/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)-stack electrodes are fabricated through the combination of direct ink writing and femtosecond laser scribing.With a footprint area of only 20 mm^(2),the on-paper MSCs exhibit excellent high-rate capacitive behavior with an areal capacitance of 5.7 mF cm^(−2)and long cycle life(>95%capacitance retention after 10,000 cycles)at a high scan rate of 1000 mV s^(−1),outperforming most of the present on-paper MSCs.Furthermore,the heterogeneous MXene/PEDOT:PSS electrodes can interconnect individual MSCs into metal-free on-paper MSC arrays,which can also be simultaneously charged/discharged at 1000 mV s^(−1),showing scalable capacitive performance.The heterogeneous MXene/PEDOT:PSS stacks are a promising electrode structure for on-paper MSCs to serve as ultrafast miniaturized energy storage components for emerging paper electronics.
基金Project supported by the Research Funds of the Key Laboratory of Fuel Cell Technology of Guangdong Province,ChinaProject(7411793079907)supported by the Guangzhou Special Foundation for Applied Basic Research+1 种基金Project(2013A15GX048)supported by the Dalian Science and Technology Project Foundation,ChinaProject(21376035)supported by the National Natural Science Foundation of China
文摘Synthesis of the spinel structure lithium manganese oxide （LiMn2O4） by supercritical hydrothermal （SH） accelerated solid state reaction （SSR） route was studied. The impacts of the reaction pressure, reaction temperature and reaction time of SH route, and the calcination temperature of SSR route on the purity, particle morphology and electrochemical properties of the prepared LiMn2O4 materials were studied. The experimental results show that after 15 min reaction in SH route at 400 ℃ and 30 MPa, the reaction time of SSR could be significantly decreased, e.g. down to 3 h with the formation temperature of 800 ℃, compared with the conventional solid state reaction method. The prepared LiMn2O4 material exhibits good crystallinity, uniform size distribution and good electrochemical performance, and has an initial specific capacity of 120 mA.h/g at a rate of 0.1C （1C=148 mA/g） and a good rate capability at high rates, even up to 50C.
基金supported by the Natural Science Foundation of Shandong Province(ZR2022QB025 and ZR2021QF070)the Start-up Foundation of Qingdao University(DC2000005025)。
文摘Layered sodium trititanate(Na_(2)Ti_(3)O_(7),NTO)is a promising anode material for sodium-ion batteries(NIBs)for large-scale energy storage applications because of its relatively low charge potential and low cost.However,NTO suffers from unsatisfactory structural stability against cycling and poor electron conductivity.Herein,an isovalent doping strategy using Sn^(4+)to partially replace Ti^(4+)is demonstrated for improving the cycling stability and rate capability of NTO.The isovalent doping of Sn^(4+)does not alter the valence state of Ti^(4+),thus maintaining the lattice integrality and structural stability.Moreover,the Sn^(4+)dopant creates more Na^(+)-preferable travel channels and expands the interlayer spacing,thus increasing Na^(+)diffusivity.As a result,a Sn^(4+)-doped Na_(2)Ti_(3)O_7(NSTO)electrode exhibits a reversible Na^(+)storage specific capacity of 176 mA h g^(-1)at 0.1C and an ultra-long cycling life with 80.2%capacity retention after5000 cycles at 1C,far outperforming the undoped and aliovalent-doping NTO electrodes reported in the literature.In addition,the NSTO electrode delivers a rate capability of 102 mA h g^(-1)at 5C,higher than that of the NTO electrode(62 mA h g^(-1)).In situ X-ray diffraction characterization results reveal that Na^(+)storage in NSTO undergoes a partial solid-solution reaction mechanism,which is completely different from the two-phase transition mechanism of NTO.Density functional theory calculation results demonstrate that Sn^(4+)doping strengthens the Ti-O bond,contributing to structural stability.This work provides a robust approach to significantly improving the electrochemical performance of NTO-based anode materials for developing long-life NIBs.
基金financially supported by the National Natural Science Foundation of China(Nos.52271211 and 52072120)the Science and Technology Innovation Program of Hunan Province,China(Nos.2022RC3037 and 2023RC3185)+1 种基金Hunan Provincial Natural Science Foundation Regional Joint Fund,China(No.2024JJ7205)the HORIZON-Marie Sklodowska-Curie Actions-2021-PF,European Union(No.101065098)
文摘Cubic phase cobalt disulfide(CoS_(2))is recognized as a potential negative material for sodium-ion batteries(SIBs)because of its low band gap,simple synthesis process,and high capacity.Nonetheless,the challenges of slow ion diffusion and substantial volume change during cycling,resulting in inadequate rate and cycling performances,remain unresolved.Here,a porous structure is fabricated by etching electrospun carbon nanofibers,subsequently facilitating the growth of CoS_(2)nanoparticles at the pore locations.A nitrogen-doped carbon layer is then applied to the surface to buffer the volumetric expansion effect of CoS_(2).The findings indicate that the carbon nanofibers establish a stable conductive network,while the porous architecture of the carbon fibers,in conjunction with the carbon coating,efficiently mitigates volumetric expansion.Furthermore,density functional theory(DFT)studies show the presence of an interlayer van der Waals force between the sulfur atoms in CoS_(2)and the carbon atoms,which reduces the band gap,enhances the conductivity of the structure,and lowers the energy barrier of Na^(+)migration.The as-prepared anode achieves a reversible capacity of 302.6 mAh g^(-1)at 3.2 A g^(-1)and maintains a capacity of 384.6 mAh g^(-1)at 1.0 A g^(-1)over 800 cycles,demonstrating exceptional rate performance and improved cycling stability.This work shows that the combination of hierarchical porous architecture and a unique electronic structure offers valuable insights for designing high-performance negative materials for SIB s.
基金funding support from the Beijing Natural Science Foundation(2252055)the National Natural Science Foundation of China(52072033 and 52271234)+1 种基金the State Key Laboratory of Clean Energy Utilization(Open Fund Project,ZJUCEU2024010)the BIT Research and Innovation Promoting Project(2024YCXY040,GIIP2023-34)。
文摘Na_(2)FePO_(4)F is a promising sodium ion cathode due to its low cost,non-toxicity,and high stability.However,the sluggish Na^(+)diffusion kinetics and limited intrinsic electronic conductivity critically restrict its worldwide application.Herein,an anion-substitution strategy is proposed with SiO_(4)^(4-)as the dopant.SiO_(4)^(4-)substitution for PO_(4)^(3-)can apparently alter the localized electronic density and structural configuration in the lattice of Na_(2)FePO_(4)F,effectively elevating the charge transfer efficiency.As a result,the electrochemical reaction kinetics of Na_(2)FePO_(4)F is significantly enhanced,which is well demonstrated by a series of electrochemical characterizations.As-obtained Na_(2.2)Fe(PO_(4))_(0.8)(SiO_(4))_(0.2)F renders a specific capacity of 84.9 m A h g^(-1)within the region of 2.5-4.0 V at 60 mA g^(-1)(0.5 C),good rate capability,and a capacity retention of 70.0% after 1000 cycles at 1.24 A g^(-1)(10 C).Furthermore,the stabilities of the cathode-electrolyte interface and structure are strengthened,which are verified by in situ EIS and ex situ XRD analysis.These findings highlight silicate anion substitution as a promising and cost-effective strategy for overcoming the limitations of Na_(2)FePO_(4)F,contributing to the development of sustainable energy storage solutions.
基金supported by the National Natural Science Foundation of China(52472194,52101243)the Natural Science Foundation of Guangdong Province,China(2023A1515012619,2025A1515012571,2025A1515010345)the Science and Technology Planning Project of Guangzhou(202201010565).
文摘Sodium-ion batteries are receiving more and more attention due to their low cost and abundant sodium storage capacity,and are considered to be a promising alternative to lithium-ion batteries.A large number of studies have shown that constructing heterostructures are considered an effective strategy to solve the hysteresis problem of electronic and ion dynamics in sodiumion battery anode materials.Herein,a nickel-cobalt bimetallic coordination polymer(NiCoCP)was synthesized using a coprecipitation method,and a CoSe_(2)@NiSe_(2) cross-stacked structure was obtained through high-temperature carbonization and selenization processes.CoSe_(2)@NiSe_(2) has a unique heterostructure and carbon film,which synergistically increases a large number of adsorption sites and alleviates the diffusion energy barrier,thereby improving the rapid diffusion kinetics of Na^(+)ions.It has superior rate performance and long-lasting cycle life.For sodium-ion batteries(SIBs),the specific capacity of CoSe_(2)@NiSe_(2) is around 460 mA h g^(-1) after 400 cycles at 1.0 A g^(-1).For potassium-ion batteries(PIBs),CoSe_(2)@NiSe_(2) also exhibits excellent cycling stability,maintaining a specific capacity of 160 mA h g^(-1) after 700 cycles at 1.0 A g^(-1).This study provides a new way to prepare metal selenide heterostructure as the promising anode material for SIBs.
基金This work was supported by Guangdong Basic and Applied Basic Research Foundation,China(No.2019A1515110980)research project from the National Natural Science Foundation of China(No.21361162004)China Scholarship Council,and CSIRO.We acknowledge Dr Yesim Gozukara,Dr Malisja de Vries,and Dr Yunxia Yang from CSIRO(Clayton)for their help with material characterization training.
文摘As promising anodes for sodium-ion batteries,metal sulfides ubiquitously suffer from low-rate and high-plateau issues,greatly hindering their application in full-cells.Herein,exemplifying carbon nanotubes(CNTs)-stringed metal sulfides superstructure(CSC)assembled by nano-dispersed SnS_(2) and CoS_(2) phases,cocktail mediation effect similar to that of high-entropy materials is initially studied in ether-based electrolyte to solve the challenges.The high nano-dispersity of metal sulfides in CSC anode underlies the cocktail-like mediation effect,enabling the circumvention of intrinsic drawbacks of different metal sulfides.By utilizing ether-based electrolyte,the reversibility of metal sulfides is greatly improved,sustaining a long-life effectivity of cocktail-like mediation.As such,CSC effectively overcomes low-rate flaw of SnS_(2) and highplateau demerit of CoS_(2),simultaneously realizes a high rate and a low plateau.In half-cells,CSC delivers an ultrahigh-rate capability of 327.6 mAh g^(−1) anode at 20 A g^(−1),far outperforming those of monometallic sulfides(SnS_(2),CoS_(2))and their mixtures.Compared with CoS_(2) phase and SnS_(2)/CoS_(2) mixture,CSC shows remarkably lowered average charge voltage up to ca.0.62 V.As-assembled CSC//Na1.5VPO4.8F0.7 full-cell shows a good rate capability(0.05~1.0 A g^(−1),120.3 mAh g^(−1) electrode at 0.05 A g^(−1))and a high average discharge voltage up to 2.57 V,comparable to full-cells with alloy-type anodes.Kinetics analysis verifies that the cocktail-like mediation effect largely boosts the charge transfer and ionic diffusion in CSC,compared with single phase and mixed phases.Further mechanism study reveals that alternative and complementary electrochemical processes between nano-dispersed SnS_(2) and CoS_(2) phases are responsible for the lowered charge voltage of CSC.This electrolyte/structure-dependent cocktail-like mediation effect effectively enhances the practicability of metal sulfide anodes,which will boost the development of high-rate/-voltage sodium-ion full batteries.
