Silicon-based(Si-based)materials with high specific capacity are driving the electric vehicle industry and the power storage market.However,poor electrical conductivity and volume expansion during cycling limit its fu...Silicon-based(Si-based)materials with high specific capacity are driving the electric vehicle industry and the power storage market.However,poor electrical conductivity and volume expansion during cycling limit its further application.Rational structural designs and specific material selections can be used to create robust volume buffer structures and conductive networks,which consequently contribute to the electrochemical performance of Si materials.Herein,Si particles were encapsulated in the hollow tubular carbon fiber(HT).Further,the porous carbon layer and SnS_(2)nanosheets were hierarchically assembled on the surface of fibers to create free-standing films with a yolk@multi-shell structure.The unique yolk@multi-shell structure provides sufficient reserved cavities,porous structure,and multiple buffers to significantly resist volume changes.The final electrode is endowed with a multi-dimensional integrated conductive structure by HT and SnS_(2)nanosheets,which greatly improves the poor conductivity of Sibased electrodes.Finally,the free-standing films can be used directly as anodes,achieving a high specific capacity of 1513.6 mAh g^(-1)after 100 cycles at 0.1 A g^(-1).Additionally,the assembled full cell showed 331.4 mAh g^(-1)after 100 cycles at 0.2 A g^(-1),which contributes significantly to the advancement of power electronics technology.展开更多
SnO_(2)-based anodes for lithium-ion batteries(LIBs)experience volume expansion,leading to rapid capacity decay and low conductivity.To address this problem,a composite consists of C/SnO_(2) with a core-shell structur...SnO_(2)-based anodes for lithium-ion batteries(LIBs)experience volume expansion,leading to rapid capacity decay and low conductivity.To address this problem,a composite consists of C/SnO_(2) with a core-shell structure and a carbonized nitrogen-doped Co-metal organic framework(Co-MOF)(NC)supported on carbon cloth(CC)was designed and prepared,which was denoted as C/SnO_(2)@NC@CC.C/SnO_(2)@NC@CC could be used directly as a flexible anode for LIBs.The combination of core-shell structure centered on carbon spheres,carbonized nitrogen-doped Co-MOF,and CC not only restricts the volume expansion but also functions as conductive networks to improve the electrical conductivity.C/SnO_(2)@NC@CC exhibits excellent electrochemical performance with charge and discharge specific capacities of 2066.0 and 2077.1 mAh/g,respectively,after 120 cycles at a current density of 0.5 A/g.展开更多
The limited ion/electron transport kinetics and insufficient crystalline stability of TiNb_(2)O_(7)(TNO)present significant challenges to the development of high-performance lithium-ion batteries(LIBs)with fastchargin...The limited ion/electron transport kinetics and insufficient crystalline stability of TiNb_(2)O_(7)(TNO)present significant challenges to the development of high-performance lithium-ion batteries(LIBs)with fastcharging capabilities and long cycle life.Here we propose a dual-modification strategy combining Ndoped carbon(NC)coating and Co^(2+)/W^(6+)doping,which not only enhances ionic and electronic conductivity but also effectively regulates volume expansion during electrochemical cycling.Upon Li+ion insertion,a significant reduction in the unit cell expansion coefficient of doped TNO is observed,from 7.48%(pristine TNO)to 5.37%(with 3%W^(6+)doping)and 4.65%(with 3%Co^(2+)doping),alo ng with lowered lattice distortion and improved uniformity in internal strain release.Density functional theory(DFT)simulation demonstrates that Co^(2+)and W^(6+)ions preferentially substitute Ti^(4+)sites in the TNO crystal,leading to the improved electronic conductivity by narrowing the bandgap.Moreover,Co^(2+)doping creates lower electron density and wider Li+ion transport channels than W^(6+)doping.The optimized 3Co-TNO@NC anode delivers a remarkable power density of 11.0 kW kg^(-1)at 20 C while maintaining a high reversible capacity of 150.9 mAh g^(-1)at 10 C after 2000 cycles.It also exhibits excellent compatibility in full cells,paired well with LiFePO_(4)(137.9 mAh g^(-1)after 2000 cycles)and Ni-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)(130.9 mAh g^(-1)after 500cycles)cathodes at 5 C,highlighting its potential as a high-safety,low-strain anode material for highpower LIBs.展开更多
Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to...Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.展开更多
As a prevailing cathode material of lithium-ion batteries(LIBs),LiCoO_(2)(LCO)still encounters the tricky problems of structural collapse,whose morphological engineering and cation doping are crucial for surmounting t...As a prevailing cathode material of lithium-ion batteries(LIBs),LiCoO_(2)(LCO)still encounters the tricky problems of structural collapse,whose morphological engineering and cation doping are crucial for surmounting the mechanical strains and alleviating phase degradation upon cycling.Hereinafter,we propose a strategy using a zeolitic imidazolate framework(ZIF)as the self-sacrificing template to directionally prepare a series of LiNi_(0.1)Co_(0.9)O_(2)(LNCO)with tailorable electrochemical properties.The rational selection of sintering temperature imparts the superiority of the resultant products in lithium storage,during which the sample prepared at 700℃(LNCO-700)outperforms its counterparts in cyclability(156.8 mA h g^(-1)at 1 C for 200 cycles in half cells,1 C=275 mA g^(-1))and rate capability due to the expedited ion/electron transport and the strengthen mechanical robustness.The feasibility of proper Ni doping is also divulged by half/full cell tests and theoretical study,during which LNCO-700(167 mA h g^(-1)at 1 C for 100 cycles in full cells)surpasses LCO-700 in battery performance due to the mitigated phase deterioration,stabilized layered structu re,ameliorated electro nic co nductivity,a nd exalted lithium sto rage activity.This work systematically unveils tailorable electrochemical behaviors of LNCO to better direct their practical application.展开更多
The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the ...The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.展开更多
Extending the charging voltage of LiCoO_(2)(LCO)is an ongoing and promising approach to increase its energy density.However,the main challenge of the approach lies in the insuperable cathodic interfacial processes at ...Extending the charging voltage of LiCoO_(2)(LCO)is an ongoing and promising approach to increase its energy density.However,the main challenge of the approach lies in the insuperable cathodic interfacial processes at high voltage,which leads to rapid failure both in the performance and structure of the LCO cathode.Herein,a Li_(2)CO_(3)-based additive was prepared by a simple sand-milling method,enabling a low electrochemical decomposition voltage<4.6 V from commonly>4.8 V,stabilizing the interface of the LCO cathode at 4.6 V.The decomposition of Li_(2)CO_(3)provides extra Li^(+)and CO_(2)to supplement the Li consumption required in the initial irreversible interfacial reactions and rapidly form a uniform and stable cathode electrolyte interphase layer(less organic and more inorganic components)on the LCO cathode by reducing CO_(2).Thus,the phase transformation and the emergence of high-valent Co ions on the surface of LCO at 4.6 V high voltage were inhibited.Thanks to this,with 2%Li_(2)CO_(3)-based additive,the capacity retention of commercial LCO at a high voltage of 4.6 V at 0.5 C for 100 cycles was improved from 59.3%to 79.3%.This work improves the high-voltage stability of LCO and provides a new idea for realizing the high-voltage operation of batteries.展开更多
Robust covalent organic frameworks(COFs)with abundant redox-active sites have attracted intense attention for organic cathode materials due to the ordered structure and excellent stability.Herein,a two-dimensional(2D)...Robust covalent organic frameworks(COFs)with abundant redox-active sites have attracted intense attention for organic cathode materials due to the ordered structure and excellent stability.Herein,a two-dimensional(2D)crystalline copper-porphyrin covalent triazine framework(CuBCPP-CTF)was synthesized via polycondensation of 5,15-bis(4-cyanophenyl)porphyrin(H2BCPP)and followed by post-copperization.The integration of copper-porphyrin moieties and triazine linkages provides two kinds of functional sites for outstanding Li+and PF6−ions storage.Electrochemical studies reveal a high discharge capacity of 232 mAh·g^(−1)at 200 mA·g^(−1)and high mid-point voltage(2.77 V vs.Li^(+)/Li),corresponding to an outstanding energy density of 601 Wh·kg^(−1).Density functional theory calculations and ex-situ characterizations disclose the intrinsic bipolar redox mechanism of metalloporphyrin for both PF6−and Li^(+)accommodation and p-type triazine units for PF_(6)^(−)storage.展开更多
Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures...Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.展开更多
3D hierarchical flowerlike WS_(2) microspheres were synthesized through a facile one-pot hydrothermal route.The as-synthesized samples were characterized by powder X-ray powder diffraction (XRD),energy-dispersive spec...3D hierarchical flowerlike WS_(2) microspheres were synthesized through a facile one-pot hydrothermal route.The as-synthesized samples were characterized by powder X-ray powder diffraction (XRD),energy-dispersive spectroscopy (EDS),scanning electron microscopy (SEM) and Raman.SEM images of the samples reveal that the hierarchical flowerlike WS_(2) microspheres with diameters of about 3-5μm are composed of a number of curled nanosheets.Electrochemical tests such as charge/discharge,cyclic voltammetry,cycle life and rate performance were carried out on the WS_(2) sample.As an anode material for lithium-ion batteries,hierarchical flowerlike WS_(2) microspheres show excellent electrochemical performance.At a current density of100 mA·g^(-1),a high specific capacity of 647.8 mA·h·g^(-1) was achieved after 120 discharge/charge cycles.The excellent electrochemical performance of WS_(2) as an anode material for lithium-ion batteries can be attributed to its special 3D hierarchical structure.展开更多
Inactive elemental doping is commonly used to improve the structural stability of high-voltage layered transition-metal oxide cathodes.However,the one-step co-doping strategy usually results in small grain size since ...Inactive elemental doping is commonly used to improve the structural stability of high-voltage layered transition-metal oxide cathodes.However,the one-step co-doping strategy usually results in small grain size since the low diffusivity ions such as Ti^(4+)will be concentrated on grain boundaries,which hinders the grain growth.In order to synthesize large single-crystal layered oxide cathodes,considering the different diffusivities of different dopant ions,we propose a simple two-step multi-element co-doping strategy to fabricate core–shell structured LiCoO_(2)(CS-LCO).In the current work,the high-diffusivity Al^(3+)/Mg^(2+)ions occupy the core of single-crystal grain while the low diffusivity Ti^(4+)ions enrich the shell layer.The Ti^(4+)-enriched shell layer(~12 nm)with Co/Ti substitution and stronger Ti–O bond gives rise to less oxygen ligand holes.In-situ XRD demonstrates the constrained contraction of c-axis lattice parameter and mitigated structural distortion.Under a high upper cut-off voltage of 4.6 V,the single-crystal CS-LCO maintains a reversible capacity of 159.8 mAh g^(−1)with a good retention of~89%after 300 cycles,and reaches a high specific capacity of 163.8 mAh g^(−1)at 5C.The proposed strategy can be extended to other pairs of low-(Zr^(4+),Ta^(5+),and W6+,etc.)and high-diffusivity cations(Zn^(2+),Ni^(2+),and Fe^(3+),etc.)for rational design of advanced layered oxide core–shell structured cathodes for lithium-ion batteries.展开更多
Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast...Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.展开更多
The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and ...The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and long-haul electric vehicles.Monoclinic TiNb_(2)O_(7)(TNO)with the theoretical capacity of 387 mAh g^(-1)has been proposed as a high-capacity anode materials to replace Li4Ti5O12.In this work,homovalent doping strategy was used to enhance the electrochemical performance of TiNb_(2)O_(7)(TNO)by employing Zr to partial substitute Ti through solvothermal method.The doping of Zr^(4+)ions can enlarge the lattice structure without changing the chemical valence of the original elements,refine and homogenize the grains,improve the electrical conductivity,and accelerate the ion diffusion kinetics,and finally enhance the cycle and rate performance.Specifically,Z0.05-TNO shows initial discharge capacity of as high as 312.2 mAh g^(-1)at 1 C and 244.8 mAh g^(-1)at 10 C,and still maintains a high specific capacity of 171.3 mAh g^(-1)after 800 cycles at 10 C.This study provides a new strategy for high-performance fast-charging energy storage electrodes.展开更多
Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01～0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of t...Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01～0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of the LiCo 1- x RE x O 2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO 2. Moreover, the performance of LiCo 1- x RE x O 2 as the cathode material in lithium ion battery is improved, especially LiCo 1- x Y x O 2 and LiCo 1- x La x O 2. The initial charge/discharge capacities of LiCo 0.99 Y 0.01 O 2 and LiCo 0.99 La 0.01 O 2 are 174/154 (mAh·g -1 ) and 159/149 (mAh·g -1 ) respectively, while those for LiCoO 2 working in the same way are only 139/131 (mAh·g -1 ).展开更多
In this paper,the ammonia leaching process and high-energy ball milling method were adapted to recover spent LiCoO_(2) material.The ammonia reduction leaching mechanism of LiCoO_(2) material in the ammonia-sodium sulf...In this paper,the ammonia leaching process and high-energy ball milling method were adapted to recover spent LiCoO_(2) material.The ammonia reduction leaching mechanism of LiCoO_(2) material in the ammonia-sodium sulfite-ammonium chloride system was elucidated.Compared with untreated LiCoO_(2) material,the leaching equilibrium time of LiCoO_(2) after ball-milled for 5 h was reduced from 48 h to 4 h,and the leaching efficiency of lithium and cobalt was improved from 69.86%and 70.80%to 89.86%and98.22%,respectively.Importantly,the apparent activation energy and leaching kinetic equation of the reaction was calculated by the shrinking core reaction model,indicating that the reaction was controlled by the chemical reaction.展开更多
Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observ...Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observed from X-ray diffraction（XRD）increases with decreasing the Ni content or increasing the Co content.The scanning electron microscopy（SEM） images reveal that the small primary particles are agglomerated to form the secondary ones.As the Mn content increases,the primary and secondary particles become larger and the resulted particle size for the Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 is uniformly distributed in the range of100-300 nm.Although the initial discharge capacity of the Li/Li[NixCoyMn2]O2 cells reduces with decreasing the Ni content,the cyclic performance and rate capability are improved with higher Mn or Co content.The Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 can deliver excellent cyclability with a capacity retention of 97.1%after 50 cycles.展开更多
Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization...Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.展开更多
2LiFe1-xCoxPO4-Li3V2（P04）3/C was synthesized using Fel-2xCo2xVO4 as precursor which was prepared by a simple co-precipitation method. 2LiFej-xCoxPO4-Li3V2（PO4）3/C samples were characterized by X-ray diffraction （...2LiFe1-xCoxPO4-Li3V2（P04）3/C was synthesized using Fel-2xCo2xVO4 as precursor which was prepared by a simple co-precipitation method. 2LiFej-xCoxPO4-Li3V2（PO4）3/C samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. All 2LiFel-xCoxPOa-Li3V2（PO4）3/C composites are of the similar crystal structure. The XRD analysis and SEM images show that 2LiFe0.96Co0.04PO4-Li3V2（PO4）3/C sample has the best-ordered structure and the smallest particle size. The charge-discharge tests demonstrate that these powders have the best electrochemical properties with an initial discharge capacity of 144.1 mA.h/g and capacity retention of 95.6% after 100 cycles when cycled at a current density of 0.1C between 2.5 and 4.5 V.展开更多
Antimony-based materials with high capacities and moderate potentials are promising anodes for lithium-/-sodium-ion batteries.However,their tremendous volume expansion and inferior conductivity lead to poor structural...Antimony-based materials with high capacities and moderate potentials are promising anodes for lithium-/-sodium-ion batteries.However,their tremendous volume expansion and inferior conductivity lead to poor structural stability and sluggish reaction kinetics.Herein,a doubleconfined nanoheterostructure Sb/Sb_(2)S_(3)@Ti_(3)C_(2)T_(x)@C has been fabricated through a solvothermal method followed by low-temperature heat treatment.The dual protection of“MXene”and“carbon”can better accommodate the volume expansion of Sb/Sb_(2)S_(3).The strong covalent bond(Ti-S,Ti-O-Sb,C-O-Sb)can firmly integrate Sb-based material with Ti_(3)C_(2)T_(x)and carbon,which significantly improves the structure stability.In addition,the carbon layer can restrain the oxidation of MXenes,and the nano-Sb/Sb_(2)S_(3)can facilitate electron/ion transport and suppress the restacking of MXenes.The heterogeneous interface between Sb and Sb_(2)S_(3)can further promote interfacial charge transfer.The MXene-Sb/Sb_(2)S_(3)@C-1 with the optimal Sb content shows high specific capacities,comparable rate properties and ultra-stable cycling performances(250 m Ah·g^(-1)after 2500 cycles at 1 A·g^(-1)for sodium-ion batteries).Ex situ X-ray diffractometer(XRD)test reveals the storage mechanism including the conversion and alloying process of MXene-Sb/Sb_(2)S_(3)@C-1.Cyclic voltammetry(CV)test results demonstrate that the pseudocapacitance behavior is dominant in MXene-Sb/Sb_(2)S_(3)@C-1,especially at large current.This design paves the way for exploring high-performance alloy-based/conversion-type anode for energy storage devices.展开更多
A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDO...A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more homogeneously.Besides,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress mitigation.This paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.展开更多
基金supported by the Shanghai Aerospace Science and Technology Innovation Fundation(No.SAST2020105)the Natural Science Basic Research Program of Shaanxi Province(No.2024JC-YBQN-0442)+1 种基金We would also like to acknowledge Analytical&Testing Center of Northwestern Polytechnical University for the Equipment Support Provided for FETEM(FEI Talos F200X)SEM(FEI Verios G4).
文摘Silicon-based(Si-based)materials with high specific capacity are driving the electric vehicle industry and the power storage market.However,poor electrical conductivity and volume expansion during cycling limit its further application.Rational structural designs and specific material selections can be used to create robust volume buffer structures and conductive networks,which consequently contribute to the electrochemical performance of Si materials.Herein,Si particles were encapsulated in the hollow tubular carbon fiber(HT).Further,the porous carbon layer and SnS_(2)nanosheets were hierarchically assembled on the surface of fibers to create free-standing films with a yolk@multi-shell structure.The unique yolk@multi-shell structure provides sufficient reserved cavities,porous structure,and multiple buffers to significantly resist volume changes.The final electrode is endowed with a multi-dimensional integrated conductive structure by HT and SnS_(2)nanosheets,which greatly improves the poor conductivity of Sibased electrodes.Finally,the free-standing films can be used directly as anodes,achieving a high specific capacity of 1513.6 mAh g^(-1)after 100 cycles at 0.1 A g^(-1).Additionally,the assembled full cell showed 331.4 mAh g^(-1)after 100 cycles at 0.2 A g^(-1),which contributes significantly to the advancement of power electronics technology.
基金National Natural Science Foundation of China(No.61376017)。
文摘SnO_(2)-based anodes for lithium-ion batteries(LIBs)experience volume expansion,leading to rapid capacity decay and low conductivity.To address this problem,a composite consists of C/SnO_(2) with a core-shell structure and a carbonized nitrogen-doped Co-metal organic framework(Co-MOF)(NC)supported on carbon cloth(CC)was designed and prepared,which was denoted as C/SnO_(2)@NC@CC.C/SnO_(2)@NC@CC could be used directly as a flexible anode for LIBs.The combination of core-shell structure centered on carbon spheres,carbonized nitrogen-doped Co-MOF,and CC not only restricts the volume expansion but also functions as conductive networks to improve the electrical conductivity.C/SnO_(2)@NC@CC exhibits excellent electrochemical performance with charge and discharge specific capacities of 2066.0 and 2077.1 mAh/g,respectively,after 120 cycles at a current density of 0.5 A/g.
基金support from the BRICS STI Framework Programme(No.52261145703)National Research Foundation+2 种基金Singapore under Award No.NRF-CRP24-2020-0002the Italy-Singapore Science and Technology Cooperation(Grant No.R23101R040)the use of computing resources at the A*STAR Computational Centre and National Supercomputer Centre,Singapore。
文摘The limited ion/electron transport kinetics and insufficient crystalline stability of TiNb_(2)O_(7)(TNO)present significant challenges to the development of high-performance lithium-ion batteries(LIBs)with fastcharging capabilities and long cycle life.Here we propose a dual-modification strategy combining Ndoped carbon(NC)coating and Co^(2+)/W^(6+)doping,which not only enhances ionic and electronic conductivity but also effectively regulates volume expansion during electrochemical cycling.Upon Li+ion insertion,a significant reduction in the unit cell expansion coefficient of doped TNO is observed,from 7.48%(pristine TNO)to 5.37%(with 3%W^(6+)doping)and 4.65%(with 3%Co^(2+)doping),alo ng with lowered lattice distortion and improved uniformity in internal strain release.Density functional theory(DFT)simulation demonstrates that Co^(2+)and W^(6+)ions preferentially substitute Ti^(4+)sites in the TNO crystal,leading to the improved electronic conductivity by narrowing the bandgap.Moreover,Co^(2+)doping creates lower electron density and wider Li+ion transport channels than W^(6+)doping.The optimized 3Co-TNO@NC anode delivers a remarkable power density of 11.0 kW kg^(-1)at 20 C while maintaining a high reversible capacity of 150.9 mAh g^(-1)at 10 C after 2000 cycles.It also exhibits excellent compatibility in full cells,paired well with LiFePO_(4)(137.9 mAh g^(-1)after 2000 cycles)and Ni-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)(130.9 mAh g^(-1)after 500cycles)cathodes at 5 C,highlighting its potential as a high-safety,low-strain anode material for highpower LIBs.
基金supported by the National Natural Science Foundation of China(No.22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(No.XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(No.XJ2023G027)。
文摘Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.
基金the financial support from the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(“Climbing Program”Special Funds,pdjh2023b0145)Guangdong Provincial International Joint Research Center for Energy Storage Materials(2023A0505090009)。
文摘As a prevailing cathode material of lithium-ion batteries(LIBs),LiCoO_(2)(LCO)still encounters the tricky problems of structural collapse,whose morphological engineering and cation doping are crucial for surmounting the mechanical strains and alleviating phase degradation upon cycling.Hereinafter,we propose a strategy using a zeolitic imidazolate framework(ZIF)as the self-sacrificing template to directionally prepare a series of LiNi_(0.1)Co_(0.9)O_(2)(LNCO)with tailorable electrochemical properties.The rational selection of sintering temperature imparts the superiority of the resultant products in lithium storage,during which the sample prepared at 700℃(LNCO-700)outperforms its counterparts in cyclability(156.8 mA h g^(-1)at 1 C for 200 cycles in half cells,1 C=275 mA g^(-1))and rate capability due to the expedited ion/electron transport and the strengthen mechanical robustness.The feasibility of proper Ni doping is also divulged by half/full cell tests and theoretical study,during which LNCO-700(167 mA h g^(-1)at 1 C for 100 cycles in full cells)surpasses LCO-700 in battery performance due to the mitigated phase deterioration,stabilized layered structu re,ameliorated electro nic co nductivity,a nd exalted lithium sto rage activity.This work systematically unveils tailorable electrochemical behaviors of LNCO to better direct their practical application.
基金supported by the National Key R&D Program of China(No.2022YFB2404400)the National Natural Science Foundation of China(Nos.U23A20577,52372168,92263206 and 21975006)+1 种基金the“The Youth Beijing Scholars program”(No.PXM2021_014204_000023)the Beijing Natural Science Foundation(Nos.2222001 and KM202110005009).
文摘The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.
基金supported by the National Key Research and Development Program of China(2022YFB2502103)the Xiamen Science and Technology Project(No.3502Z20231057)+2 种基金the National Natural Science Foundation of China(No.22288102,No.22279107,No.22309153)the Fujian Provincial Natural Science Foundation of China(No.2024J01040)the Fundamental Research Funds for the Central Universities(No.20720230039)。
文摘Extending the charging voltage of LiCoO_(2)(LCO)is an ongoing and promising approach to increase its energy density.However,the main challenge of the approach lies in the insuperable cathodic interfacial processes at high voltage,which leads to rapid failure both in the performance and structure of the LCO cathode.Herein,a Li_(2)CO_(3)-based additive was prepared by a simple sand-milling method,enabling a low electrochemical decomposition voltage<4.6 V from commonly>4.8 V,stabilizing the interface of the LCO cathode at 4.6 V.The decomposition of Li_(2)CO_(3)provides extra Li^(+)and CO_(2)to supplement the Li consumption required in the initial irreversible interfacial reactions and rapidly form a uniform and stable cathode electrolyte interphase layer(less organic and more inorganic components)on the LCO cathode by reducing CO_(2).Thus,the phase transformation and the emergence of high-valent Co ions on the surface of LCO at 4.6 V high voltage were inhibited.Thanks to this,with 2%Li_(2)CO_(3)-based additive,the capacity retention of commercial LCO at a high voltage of 4.6 V at 0.5 C for 100 cycles was improved from 59.3%to 79.3%.This work improves the high-voltage stability of LCO and provides a new idea for realizing the high-voltage operation of batteries.
基金supported by the National Natural Science Foundation of China(Nos.22261132512,22235001,22175020,and 22131005)Guizhou Provincial Key Laboratory Platform Project(No.ZSYS[2025]008)+1 种基金Talent Program of Guizhou University(No.[2024]11)Xiaomi Young Scholar Program,and University of Science and Technology Beijing.
文摘Robust covalent organic frameworks(COFs)with abundant redox-active sites have attracted intense attention for organic cathode materials due to the ordered structure and excellent stability.Herein,a two-dimensional(2D)crystalline copper-porphyrin covalent triazine framework(CuBCPP-CTF)was synthesized via polycondensation of 5,15-bis(4-cyanophenyl)porphyrin(H2BCPP)and followed by post-copperization.The integration of copper-porphyrin moieties and triazine linkages provides two kinds of functional sites for outstanding Li+and PF6−ions storage.Electrochemical studies reveal a high discharge capacity of 232 mAh·g^(−1)at 200 mA·g^(−1)and high mid-point voltage(2.77 V vs.Li^(+)/Li),corresponding to an outstanding energy density of 601 Wh·kg^(−1).Density functional theory calculations and ex-situ characterizations disclose the intrinsic bipolar redox mechanism of metalloporphyrin for both PF6−and Li^(+)accommodation and p-type triazine units for PF_(6)^(−)storage.
基金supported by the National Natural Science Foundation of China(22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(XJ2023G027).
文摘Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.
基金Funded by the Jiangsu Province Industry-University-Research Cooperation Project (No.BY2018314)the Scientific Research Foundation of Jiangsu University of Technology (No.KYY18030)Jiangsu Overseas Visiting Scholar Program for University Prominent Young&Middle-aged Teachers and Presidents。
文摘3D hierarchical flowerlike WS_(2) microspheres were synthesized through a facile one-pot hydrothermal route.The as-synthesized samples were characterized by powder X-ray powder diffraction (XRD),energy-dispersive spectroscopy (EDS),scanning electron microscopy (SEM) and Raman.SEM images of the samples reveal that the hierarchical flowerlike WS_(2) microspheres with diameters of about 3-5μm are composed of a number of curled nanosheets.Electrochemical tests such as charge/discharge,cyclic voltammetry,cycle life and rate performance were carried out on the WS_(2) sample.As an anode material for lithium-ion batteries,hierarchical flowerlike WS_(2) microspheres show excellent electrochemical performance.At a current density of100 mA·g^(-1),a high specific capacity of 647.8 mA·h·g^(-1) was achieved after 120 discharge/charge cycles.The excellent electrochemical performance of WS_(2) as an anode material for lithium-ion batteries can be attributed to its special 3D hierarchical structure.
基金the Hong Kong Polytechnic University(Q-CDBG),the Science and Technology Program of Guangdong Province of China(2020A0505090001)the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.PolyU152178/20E)+2 种基金the National Natural Science Foundation of China(22379052)the Natural Science Foundation of Guangdong(No.2022A1515011667)China Postdoctoral Science Foundation(2021T140268).
文摘Inactive elemental doping is commonly used to improve the structural stability of high-voltage layered transition-metal oxide cathodes.However,the one-step co-doping strategy usually results in small grain size since the low diffusivity ions such as Ti^(4+)will be concentrated on grain boundaries,which hinders the grain growth.In order to synthesize large single-crystal layered oxide cathodes,considering the different diffusivities of different dopant ions,we propose a simple two-step multi-element co-doping strategy to fabricate core–shell structured LiCoO_(2)(CS-LCO).In the current work,the high-diffusivity Al^(3+)/Mg^(2+)ions occupy the core of single-crystal grain while the low diffusivity Ti^(4+)ions enrich the shell layer.The Ti^(4+)-enriched shell layer(~12 nm)with Co/Ti substitution and stronger Ti–O bond gives rise to less oxygen ligand holes.In-situ XRD demonstrates the constrained contraction of c-axis lattice parameter and mitigated structural distortion.Under a high upper cut-off voltage of 4.6 V,the single-crystal CS-LCO maintains a reversible capacity of 159.8 mAh g^(−1)with a good retention of~89%after 300 cycles,and reaches a high specific capacity of 163.8 mAh g^(−1)at 5C.The proposed strategy can be extended to other pairs of low-(Zr^(4+),Ta^(5+),and W6+,etc.)and high-diffusivity cations(Zn^(2+),Ni^(2+),and Fe^(3+),etc.)for rational design of advanced layered oxide core–shell structured cathodes for lithium-ion batteries.
基金supported by the Natural Science Foundation of Jiangsu Province of China(No.BK20201008).
文摘Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.
基金supported by the National Natural Science Foundation of China(52272258)Beijing Nova Program(20220484214)+1 种基金Fundamental Research Funds for the Central Universities(No.2021JCCXJD01)Key R&D and transformation projects in Qinghai Province(2021-HZ-808)and Hebei Province(21314401D).
文摘The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and long-haul electric vehicles.Monoclinic TiNb_(2)O_(7)(TNO)with the theoretical capacity of 387 mAh g^(-1)has been proposed as a high-capacity anode materials to replace Li4Ti5O12.In this work,homovalent doping strategy was used to enhance the electrochemical performance of TiNb_(2)O_(7)(TNO)by employing Zr to partial substitute Ti through solvothermal method.The doping of Zr^(4+)ions can enlarge the lattice structure without changing the chemical valence of the original elements,refine and homogenize the grains,improve the electrical conductivity,and accelerate the ion diffusion kinetics,and finally enhance the cycle and rate performance.Specifically,Z0.05-TNO shows initial discharge capacity of as high as 312.2 mAh g^(-1)at 1 C and 244.8 mAh g^(-1)at 10 C,and still maintains a high specific capacity of 171.3 mAh g^(-1)after 800 cycles at 10 C.This study provides a new strategy for high-performance fast-charging energy storage electrodes.
文摘Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01～0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of the LiCo 1- x RE x O 2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO 2. Moreover, the performance of LiCo 1- x RE x O 2 as the cathode material in lithium ion battery is improved, especially LiCo 1- x Y x O 2 and LiCo 1- x La x O 2. The initial charge/discharge capacities of LiCo 0.99 Y 0.01 O 2 and LiCo 0.99 La 0.01 O 2 are 174/154 (mAh·g -1 ) and 159/149 (mAh·g -1 ) respectively, while those for LiCoO 2 working in the same way are only 139/131 (mAh·g -1 ).
基金financially supported by the National Natural Science Foundation of China(Nos.51822812,51778627)the Fundamental Research Funds for the Central Universities of Central South University(No.2020zzts474)。
文摘In this paper,the ammonia leaching process and high-energy ball milling method were adapted to recover spent LiCoO_(2) material.The ammonia reduction leaching mechanism of LiCoO_(2) material in the ammonia-sodium sulfite-ammonium chloride system was elucidated.Compared with untreated LiCoO_(2) material,the leaching equilibrium time of LiCoO_(2) after ball-milled for 5 h was reduced from 48 h to 4 h,and the leaching efficiency of lithium and cobalt was improved from 69.86%and 70.80%to 89.86%and98.22%,respectively.Importantly,the apparent activation energy and leaching kinetic equation of the reaction was calculated by the shrinking core reaction model,indicating that the reaction was controlled by the chemical reaction.
基金Project(21473258)supported by the National Natural Science Foundation of ChinaProject(13JJ1004)supported by the Distinguished Young Scientists of Hunan Province,ChinaProject(NCET-11-0513)supported by the New Century Excellent Talents in University,China
文摘Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observed from X-ray diffraction（XRD）increases with decreasing the Ni content or increasing the Co content.The scanning electron microscopy（SEM） images reveal that the small primary particles are agglomerated to form the secondary ones.As the Mn content increases,the primary and secondary particles become larger and the resulted particle size for the Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 is uniformly distributed in the range of100-300 nm.Although the initial discharge capacity of the Li/Li[NixCoyMn2]O2 cells reduces with decreasing the Ni content,the cyclic performance and rate capability are improved with higher Mn or Co content.The Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 can deliver excellent cyclability with a capacity retention of 97.1%after 50 cycles.
基金Project supported by Ministry of Education Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, China Project (2010JK765) supported by the Education Department of Shaanxi Province, China
文摘Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.
基金Project(51072233) supported by National Natural Science Foundation of China
文摘2LiFe1-xCoxPO4-Li3V2（P04）3/C was synthesized using Fel-2xCo2xVO4 as precursor which was prepared by a simple co-precipitation method. 2LiFej-xCoxPO4-Li3V2（PO4）3/C samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. All 2LiFel-xCoxPOa-Li3V2（PO4）3/C composites are of the similar crystal structure. The XRD analysis and SEM images show that 2LiFe0.96Co0.04PO4-Li3V2（PO4）3/C sample has the best-ordered structure and the smallest particle size. The charge-discharge tests demonstrate that these powders have the best electrochemical properties with an initial discharge capacity of 144.1 mA.h/g and capacity retention of 95.6% after 100 cycles when cycled at a current density of 0.1C between 2.5 and 4.5 V.
基金supported by the National Natural Science Foundation of China(Nos.52071073,52177208,52171202 and 51971055)Hebei Province"333 talent project"(No.C20221012)+2 种基金the Natural Science Foundation of Hebei Province(No.E2020501004)the Fundamental Research Funds for the Central Universities(No.N2123032)the Science and Technology Project of Hebei Education Department(No.BJK2023005)。
文摘Antimony-based materials with high capacities and moderate potentials are promising anodes for lithium-/-sodium-ion batteries.However,their tremendous volume expansion and inferior conductivity lead to poor structural stability and sluggish reaction kinetics.Herein,a doubleconfined nanoheterostructure Sb/Sb_(2)S_(3)@Ti_(3)C_(2)T_(x)@C has been fabricated through a solvothermal method followed by low-temperature heat treatment.The dual protection of“MXene”and“carbon”can better accommodate the volume expansion of Sb/Sb_(2)S_(3).The strong covalent bond(Ti-S,Ti-O-Sb,C-O-Sb)can firmly integrate Sb-based material with Ti_(3)C_(2)T_(x)and carbon,which significantly improves the structure stability.In addition,the carbon layer can restrain the oxidation of MXenes,and the nano-Sb/Sb_(2)S_(3)can facilitate electron/ion transport and suppress the restacking of MXenes.The heterogeneous interface between Sb and Sb_(2)S_(3)can further promote interfacial charge transfer.The MXene-Sb/Sb_(2)S_(3)@C-1 with the optimal Sb content shows high specific capacities,comparable rate properties and ultra-stable cycling performances(250 m Ah·g^(-1)after 2500 cycles at 1 A·g^(-1)for sodium-ion batteries).Ex situ X-ray diffractometer(XRD)test reveals the storage mechanism including the conversion and alloying process of MXene-Sb/Sb_(2)S_(3)@C-1.Cyclic voltammetry(CV)test results demonstrate that the pseudocapacitance behavior is dominant in MXene-Sb/Sb_(2)S_(3)@C-1,especially at large current.This design paves the way for exploring high-performance alloy-based/conversion-type anode for energy storage devices.
基金the National Research Foundation of Korea(Nos.2018R1A5A7023490 and 2022R1A2C1003003)。
文摘A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more homogeneously.Besides,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress mitigation.This paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.
