Transition metal sulfides have great potential as anode mterials for sodium-ion batteries(SIBs)due to their high theoretical specific capacities.However,the inferior intrinsic conductivity and large volume variation d...Transition metal sulfides have great potential as anode mterials for sodium-ion batteries(SIBs)due to their high theoretical specific capacities.However,the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cyde performance,unbeneficial for the application as fast-charging and long-cycling SIBs anode.Herein,the three-dimensional porous Cu_(1.81)S/nitrogen-doped carbon frameworks(Cu_(1.81)S/NC)are synthesized by the simple and facile sol-gel and annealing processes,which can accommodate the volumetric expansion of Cu_(1.81)S nanoparticles and accelerate the transmission of ions and electrons during Na^(+)insertion/extraction processes,exhibiting the excellent rate capability(250.6 mA·g^(-1)at 20.0 A·g^(-1))and outstanding cycling stability(70% capacity retention for 6000 cycles at 10.0 A·g^(-1))for SIBs.Moreover,the Na-ion full cells coupled with Na_(3)V_(2)(PO_(4))_(3)/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g^(-1)at 5.0 A·g^(-1)and long-cycle performance with the 86.9% capacity retention at 2.0 A·g^(-1)after 750 cycles.This work proposes a promising way for the conversionbased metal sulfides for the applications as fast-charging sodium-ion battery anode.展开更多
Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anod...Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.展开更多
High-efficiency sodium-ion batteries(SIBs) are in great demand for energy storage applications,which are dominated by the Na+storage performance of electrode materials.Here,a one-pot solvothermal method is developed t...High-efficiency sodium-ion batteries(SIBs) are in great demand for energy storage applications,which are dominated by the Na+storage performance of electrode materials.Here,a one-pot solvothermal method is developed to construct amorphous/crystalline MoO_(2)(a/c-MoO_(2)) homojunction for boosting Na+storage.Theoretical simulations signify that electrons redistribute at the homogenous interface of a/c-MoO_(2),resulting in an inbuilt driving force to easily adsorb charge carriers and promote the electron/ion transfer ability.Relying on its crystallographic superiorities,the a/c-MoO_(2)homojunction with high Na adsorbability(-1.61 eV) and low Na diffusion energy barrier(0.519 eV) achieves higher capacity(307 mA h g^(-1)at 0.1 A/g),better rate capability and cycling stability than either a-MoO_(2)or c-MoO_(2)counterpart.Combining in-situ X-ray diffraction(XRD) and ex-situ X-ray photoelectron spectroscopy(XPS)techniques,the ’adsorption-insertion-conversion’ mechanism is well established for Na+storage of MoO_(2).Our work opens new opportunities to optimize electrode materials via crystallographic engineering for efficient Na+storage,and helps to better understand the effects of homojunction structure in enhanced electrochemical performance.展开更多
Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion...Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion of slovated Na+but allow the entrance of naked Na^(+) into the pores,which can reduce the interficial contact between the electrolyte and the inner pores without sacrificing the fast diffusion kinetics.Herein,a molten diffusion-carbonization method is proposed to transform the micropores(>1 nm)inside carbon into ultra-micropores(<0.5 nm).Consequently,the designed carbon anode displays an enhanced capacity of 346 mAh g^(−1) at 30 mA g^(−1) with a high ICE value of~80.6%and most of the capacity(~90%)is below 1 V.Moreover,the high-loading electrode(~19 mg cm^(−2))exhibits a good temperature endurance with a high areal capacity of 6.14 mAh cm^(−2) at 25℃ and 5.32 mAh cm^(−2) at −20℃.Based on the in situ X-ray diffraction and ex situ solid-state nuclear magnetic resonance results,the designed ultra-micropores provide the extra Na+storage sites,which mainly contributes to the enhanced capacity.This proposed strategy shows a good potential for the development of high-performance SIBs.展开更多
Low-temperature assembly of MXene nanosheets into three-dimensional(3D) robust aerogels addresses the crucial stability concern of the nano-building blocks during the fabrication process,which is of key importance for...Low-temperature assembly of MXene nanosheets into three-dimensional(3D) robust aerogels addresses the crucial stability concern of the nano-building blocks during the fabrication process,which is of key importance for transforming the fascinating properties at the nanoscale into the macroscopic scale for practical applications.Herein,suitable cross-linking agents(amino-propyltriethoxysilane,Mn^(2+),Fe^(2+),Zn^(2+),and Co^(2+)) as interfacial mediators to engineer the interlayer interactions are reported to realize the graphene oxide(GO)-assisted assembly of Ti_(3)C_(2)T_(x) MXene aerogel at room temperature.This elaborate aerogel construction not only suppresses the oxidation degradation of Ti_(3)C_(2)T_(x) but also generates porous aerogels with a high Ti_(3)C_(2)T_(x) content(87 wt%) and robustness,thereby guaranteeing the functional accessibility of Ti_(3)C_(2)T_(x) nanosheets and operational reliability as integrated functional materials.In combination with a further sulfur modification,the Ti_(3)C_(2)T_(x) aerogel electrode shows promising electrochemical performances as the freestanding anode for sodium-ion storage.Even at an ultrahigh loading mass of 12.3 mg cm^(-2),a pronounced areal capacity of 1.26 mAh cm^(-2) at a current density of 0.1 A g^(-1) has been achieved,which is of practical significance.This work conceptually suggests a new way to exert the utmost surface functionalities of MXenes in 3D monolithic form and can be an inspiring scaffold to promote the application of MXenes in different areas.展开更多
Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials ...Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.展开更多
Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish inte...Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish intercalation kinetics of sodium ions impedes the rate performance.Thus,the precise structure control of carbon materials is important to improve the battery performance.Herein,a 3D porous hard-soft composite carbon(3DHSC)was prepared using the NaCl as the template and phenolic resin and pitch as carbon precursors.The NaCl template restrains the growth of the graphite crystallite during the carbonization process,resulting in small graphitic domains with expanded interlayer spacing which is favorable for the sodium storage.Moreover,the Na Cl templates help to create abundant mesopores and macropores for fast sodium ion diffusion.The porous structure and the graphite crystalline structure can be precisely controlled by simply adjusting the mass ratio of Na Cl,and thus,the suitable structure can be prepared to reach high capacity and rate performance while keeping a relatively high Coulombic efficiency.Typically,a high reversible capacity(215 mA h g^(-1)at 0.05 A g^(-1)),an excellent rate capability(97 mA h g^(-1)at 5 A g^(-1)),and a high initial Coulombic efficiency(60%)are achieved.展开更多
O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on...O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.展开更多
The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by ...The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor.As an anode for SIB,HHPC-1100 exhibits a capacity of 331.7 mA h g^(-1) at 20 mA g^(-1),while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping.Moreover,the synergistic effect of O,N,S,P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study,which provide a theoretical basis for the prominent electrochemical performance of the material.展开更多
Tin selenide(SnSe)is considered as a potential anode for sodium-ion batteries(SIBs)owing to its high theoretical specific capacity.Unfortunately,it suffers from drastic volume expansion/contraction during sodium ions ...Tin selenide(SnSe)is considered as a potential anode for sodium-ion batteries(SIBs)owing to its high theoretical specific capacity.Unfortunately,it suffers from drastic volume expansion/contraction during sodium ions insertion/extraction,resulting in poor cycling stability.Herein,a pomegranate-inspired porous carbon shell wrapped heterogeneous SnSe/ZnSe composite(SnSe/ZnSe@C)is exquisitely designed and fabricated through electrostatic spraying followed by high-temperature selenization.The polyacrylonitrile-derived carbon shell acts as an adhesive to link the porous cubic SnSe/ZnSe and form highly interconnected microcircuits to improve the electron/ion transfer efficiency and inhibit the bulk volume change of internal metallic selenide nanoparticles and polyselenides dissolution during repeated cycling.Moreover,the abundant heterostructure interface of SnSe/ZnSe further significantly accelerates the electrons/ions transport.As a result,the as-prepared SnSe/ZnSe@C electrode exhibits a high specific capacity(508.3 m Ah g^(-1)at 0.05 A g^(-1)),excellent rate performance(177.8 m Ah g^(-1)at 10.0 A g^(-1)),and remarkable cycling stability(195.9 m Ah g^(-1)after 10,000 cycles at 5.0 A g^(-1)).Furthermore,in-situ Xray diffraction(XRD)/Raman,ex-situ transmission electron microscopy,and kinetic analysis clearly reveal a four-step electrochemical reaction process and battery-capacitor dual-mode sodium storage mechanism.This work provides a new perspective for developing commercial SIBs anode materials with high capacity and long lifespan.展开更多
Sodium-ion battery materials and devices are promising candidates for largescale applications,owing to the abundance and low cost of sodium sources.Emerging sodium-ion pseudocapacitive materials provide one approach f...Sodium-ion battery materials and devices are promising candidates for largescale applications,owing to the abundance and low cost of sodium sources.Emerging sodium-ion pseudocapacitive materials provide one approach for achieving high capacity at high rates,but are currently not well understood.Herein,a comprehensive overview of the fundamentals and electrochemical behaviors of vanadium-based pseudocapacitive materials for sodium-ion storage is presented.The insight of sodium-ion storage mechanisms for various vanadium-based materials,including vanadium oxides,vanadates,vanadium sulfides,nitrides,and carbides are systematically discussed and summarized.In particular,areas for further development to improve fundamental understanding of electrochemical and structural properties of materials are identified.Finally,we provide a perspective on the application of pseudocapacitive materials in high-power and high-energy sodium-ion storage devices(e.g.,sodium-ion capacitors).展开更多
Rational electrode structure design is of great significance for realizing superior Na^(+)storage performance.Herein,a metal salt-induced polymer blowing-bubble approach followed by selenization procedure is developed...Rational electrode structure design is of great significance for realizing superior Na^(+)storage performance.Herein,a metal salt-induced polymer blowing-bubble approach followed by selenization procedure is developed to in-situ generate abundant sub-10 nm CoSe_(2) nanocrystals on 3D Se/N co-doped carbon networks(CoSe_(2)@3DSNC).The phase transition from Co to CoSe_(2) and the incorporation of Se into the carbon layer are realized simultaneously to establish above configuration,in which the CoSe_(2) nanocrystals are anchored on interlayer expanded carbon networks.Such unique configuration endows electrode with lower Na+diffusion energy barrier,higher Na+storage capability and better structural durability.Reflected in SIBs,the optimized CoSe_(2)@3 DSNC delivers superior rate capability(310 m Ah g^(-1) at 10 A g^(-1))and excellent longterm cycling stability(409 m Ah g^(-1) after 1200 cycles at 5 A g^(-1)).Moreover,this configuration can also be obtained in other metal selenides-carbon composite through a similar approach.展开更多
The latest view suggests the inactive core,surface pulverization,and poly sulfide shuttling effect of metal sulfides are responsible for their low capacity and poor cycling performance in sodium-ion batteries(SIBs).Wh...The latest view suggests the inactive core,surface pulverization,and poly sulfide shuttling effect of metal sulfides are responsible for their low capacity and poor cycling performance in sodium-ion batteries(SIBs).Whereas overcoming the above problems based on conventional nanoengineering is not efficient enough.In this work,erythrocyte-like CuS microspheres with an elastic buffering layer of ultrathin poly aniline(PANI) were synthesized through one-step selfassembly growth,followed by in situ polymerization of aniline.When CuS@PANI is used as anode electrode in SIBs,it delivers high capacity,ultrahigh rate capability(500 mAh gat 0.1 A g,and 214.5 mAh gat 40 A g),and superior cycling life of over 7500 cycles at 20 A g.A series of in/ex situ characterization techniques were applied to investigate the structural evolution and sodium-ion storage mechanism.The PANI swollen with electrolyte can stabilize solid electrolyte interface layer,benefit the ion transport/charge transfer at the PANI/electrolyte interface,and restrain the size growth of Cu particles in confined space.Moreover,finite element analyses and density functional simulations confirm that the PANI film effectively buffers the volume expansion,suppresses the surface pulverization,and traps the poly sulfide.展开更多
Conversion-type anode materials with a high charge storage capability generally su er from large volume expansion, poor electron conductivity, and sluggish metal ion transport kinetics. The electrode material describe...Conversion-type anode materials with a high charge storage capability generally su er from large volume expansion, poor electron conductivity, and sluggish metal ion transport kinetics. The electrode material described in this paper, namely cobalt sulphide nanoparticles encapsulated in carbon cages(Co9S8@NC), can circumvent these problems. This electrode material exhibited a reversible sodium-ion storage capacity of 705 mAh g^-1 at 100 mA g^-1 with an extraordinary rate capability and good cycling stability. Mechanistic study using the in situ transmission electron microscope technique revealed that the volumetric expansion of the Co9S8 nanoparticles is bu ered by the carbon cages, enabling a stable electrode–electrolyte interface. In addition, the carbon shell with high-content doped nitrogen significantly enhances the electron conductivity of the Co9S8@NC electrode material and provides doping-induced active sites to accommodate sodium ions. By integrating the Co9S8@NC as negative electrode with a cellulose-derived porous hard carbon/graphene oxide composite as positive electrode and 1 M NaPF6 in diglyme as the electrolyte, the sodium-ion capacitor full cell can achieve energy densities of 101.4 and 45.8 Wh kg^-1 at power densities of 200 and 10,000 W kg^-1, respectively.展开更多
Rechargeable sodium-ion batteries(SIBs)are considered as the next-generation secondary batteries.The performance of SIB is determined by the behavior of its electrode surface and the electrode–electrolyte interface d...Rechargeable sodium-ion batteries(SIBs)are considered as the next-generation secondary batteries.The performance of SIB is determined by the behavior of its electrode surface and the electrode–electrolyte interface during charging and discharging.Thus,the characteristics of these surfaces and interfaces should be analyzed to realize large-scale energy storage systems with high energy density and long-cycle stability.Although various studies have investigated the properties of electrode materials,few studies have focused on the construction of stable and efficient SIB interfaces,and even fewer have explored the mechanisms of interfacial effects;however,the strategies of regulating interfacial effects are yet to be completely developed.Moreover,the results obtained thus far are insufficient to draw systematic conclusions.The present study reviews the literature on the mechanism of interfacial effects in Na+storage devices.The interfaces in a sodium-ion storage device include a heterogeneous interface between electrode materials,a solid electrolyte interphase,and a cathode electrolyte interphase.The interfacial effects during the intercalation,transformation,and alloy reactions and the resulting overall battery performance were theoretically analyzed.In this review,we aim to provide a theoretical basis for optimizing the structures of electrode surface and electrode–electrolyte interface to optimize the performance of SIBs.In addition,the challenges of investigating interfacial effects and several possible helpful methods and opportunities for studying the mechanisms of interfacial effects in SIBs will be presented.展开更多
Vanadium disulfide(VS_(2)) as a typical two-dimensional transition metal chalcogenide has excellent competitiveness for sodium-ion storage due to its wide layer spacing(0.575 nm),high theoretical capacity of 932mAh...Vanadium disulfide(VS_(2)) as a typical two-dimensional transition metal chalcogenide has excellent competitiveness for sodium-ion storage due to its wide layer spacing(0.575 nm),high theoretical capacity of 932mAh·g^(-1) originating from multi-electron electrochemical redox.However,continuous sodiation process accompanied by crystal structural evolution and collapse cause rapid capacity decaying.Herein,novel few-layer VS_(2)nanosheets with open(001) crystal planes are in-situ constructed on reduced graphene oxide to solve these issues mentioned above.It indicates that few-layer VS_(2)provides more Na^(+) storage activity due to the low Na^(+)surface migration energy barrier on exposed crystal(001)planes.The flexible and high electronic conductivity of carbon matrix also effectively builds multi-level buffer structure and electron transport kinetics to boost the Na^(+)insertion/conversion reactive activity on VS_(2) as well as Na^(+) pseudocapacitance storage kinetics on edges and defects of nano sheets.Those coupling effects result in high rate capability and long cycling stability as a battery/capacitor anode.It delivers conspicuous high energy density of 81 and 40 Wh·kg^(-1) at power density of 118 and 10,286W·kg^(-1),as well as 80% energy retention rate after 5000cycles,confirming its great application potential in sodiumbased storage devices.展开更多
Common evaluation methodology of sodium(Na)-containing two-electrode or three-electrode configurations overlooks the interference from highly reactive Na metal,leading to the underestimation or inconsistent performanc...Common evaluation methodology of sodium(Na)-containing two-electrode or three-electrode configurations overlooks the interference from highly reactive Na metal,leading to the underestimation or inconsistent performance of low-potential hard carbon(HC)electrodes.Herein,the trap of Na metal was systematically investigated with or without applied current,uncovering its inadequacy as the reference or counter electrode in different configurations.A Na-metal-free three-electrode protocol is proposed for evaluating the actual Na^(+)-storage capability of the typical low-potential HC electrode.By avoiding Na crosstalk and precisely controlling the working electrode's potential,the actual electrochemical performance of HC in the carbonate esterbased electrolyte can be recognized with high capacity of 222 mAh g^(-1)at 2 C and 113 mAh g^(-1)at 5 C,correcting the misunderstanding of the inferior performance of HC in coin-type half cells(68%and 50%undervaluation at 2 C and 5 C,respectively).The advanced protocol is expected to reduce misunderstandings or underestimation due to evaluation methods and to guide the development of high-performance battery materials.展开更多
Cobalt selenide(CoSe_(2))has become a promising anode material for sodium-ion batteries(SIBs)due to its stable chemical properties,environmental friendliness,and high theoretical capacity.However,the undesirable rate ...Cobalt selenide(CoSe_(2))has become a promising anode material for sodium-ion batteries(SIBs)due to its stable chemical properties,environmental friendliness,and high theoretical capacity.However,the undesirable rate capacity and cycle stability of the anode materials largely limit its applications for SIBs due to the relatively low electronic conductivity and huge volume change during the Na+insertion/extraction.In this study,electrostatic spinning combined with a wet chemical method is employed to synthesize coral-like composite material(CNF@c-CoSe_(2)/C),which is composed of CoSe_(2)/carbon nanosheet arrays(CoSe_(2)/C)and carbon nanofibers(CNFs).CoSe_(2)/C nanoflakes derived from metal-organic frameworks(MOFs)with high surface area and the porous structure can inhibit the pulverization and amorphization of CoSe_(2) during charge and discharge processes,thus significantly keeping the stability of the microstructure.CNF can limit the overgrowth of nanosheets and serve as a conductive skeleton.Compared to two-dimensional CoSe_(2)/C nanoflakes and pure CoSe_(2) nanoparticles,the composite can expose more active sites and effectively accelerate the diffusion of Na+,which displays enhanced rate capability(266.5 mAh·g^(-1) at 5.0 A·g^(-1))and cycling stability(268.3 mAh·g^(-1) after 100 cycles at 1.0 A·g^(-1)).Moreover,the rational preparation strategy for metal selenide-based heterostructure material presents a new way for high-performance SIB s.展开更多
Benefiting from the distinctive ordering degree and local microstructure characteristics,hard carbon(HC)is considered as the most promising anode for sodium-ion batteries(SIBs).Unfortunately,the low initial Coulombic ...Benefiting from the distinctive ordering degree and local microstructure characteristics,hard carbon(HC)is considered as the most promising anode for sodium-ion batteries(SIBs).Unfortunately,the low initial Coulombic efficiency(ICE)and limited reversible capacity severely impede its extensive application.Here,a homogeneous curly graphene(CG)layer with a micropore structure on HC is designed and executed by a simple chemical vapor deposition method(without catalysts).CG not only improves the electronic/ionic conductivity of the hard carbon but also effectively shields its surface defects,enhancing its ICE.In particular,due to the spontaneous curling structural characteristics of CG sheets(CGs),the micropores(≤2 nm)formed provide additional active sites,increasing its capacity.When used as a sodium-ion battery anode,the HC-CG composite anode displayed an outstanding reversible capacity of 358 mAh·g^(-1),superior ICE of 88.6%,remarkable rate performance of 145.8 mAh·g^(-1)at 5 A·g^(-1),and long cycling life after 1000 cycles with 88.6%at 1 A·g^(-1).This work provides a simple defect/microstructure turning strategy for hard carbon anodes and deepens the understanding of Na+storage behavior in the plateau region,especially on the pore-filling mechanism by forming quasi-metallic clusters.展开更多
Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-ty...Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-type mechanism for Na+storage in VN anodes but does not explain the phenomena of their size-dependent specific capacities and underlying causes of pseudocapacitive charge storage behaviors.Herein,we insightfully reveal the VN anode exhibits a surface-redox pseudocapacitive mechanism in nonaqueous,Na+-based electrolytes,as demonstrated by kinetics analysis,experimental observations,and first-principles calculations.Through ex situ X-ray photoelectron spectroscopy and semiquantitative analyses,the Na+storage is characterized by redox reactions occurring with the V5+/V4+to V3+at the surface of VN particles,which is different from the well-known conversion reaction mechanism.The pseudocapacitive performance is enhanced through nanoarchitecture design via oxidized vanadium states at the surface.The optimized VN-10 nm anode delivers a sodium-ion storage capability of 106 mAh g−1 at the high specific current of 20 A g−1,and excellent cycling performance of 5000 cycles with negligible capacity losses.This work demonstrates the emerging opportunities of utilizing pseudocapacitive charge storage for realizing high-rate sodium-ion storage applications.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.U1904173 and 52272219)the Key Research Projects of Henan Provincial Department of Education(No.19A150043)+2 种基金the Natural Science Foundation of Henan Province(Nos.202300410330 and 222300420276)the Nanhu Scholars Program for Young Scholars of Xinyang Normal Universitythe Xinyang Normal University Analysis&Testing Center。
文摘Transition metal sulfides have great potential as anode mterials for sodium-ion batteries(SIBs)due to their high theoretical specific capacities.However,the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cyde performance,unbeneficial for the application as fast-charging and long-cycling SIBs anode.Herein,the three-dimensional porous Cu_(1.81)S/nitrogen-doped carbon frameworks(Cu_(1.81)S/NC)are synthesized by the simple and facile sol-gel and annealing processes,which can accommodate the volumetric expansion of Cu_(1.81)S nanoparticles and accelerate the transmission of ions and electrons during Na^(+)insertion/extraction processes,exhibiting the excellent rate capability(250.6 mA·g^(-1)at 20.0 A·g^(-1))and outstanding cycling stability(70% capacity retention for 6000 cycles at 10.0 A·g^(-1))for SIBs.Moreover,the Na-ion full cells coupled with Na_(3)V_(2)(PO_(4))_(3)/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g^(-1)at 5.0 A·g^(-1)and long-cycle performance with the 86.9% capacity retention at 2.0 A·g^(-1)after 750 cycles.This work proposes a promising way for the conversionbased metal sulfides for the applications as fast-charging sodium-ion battery anode.
基金supported by the Natural Science Foundation of China(5207123251871165)。
文摘Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.
基金Financial support by National Natural Science Foundation of China(21706103 and U21A20311)Natural Science Foundation of Jiangsu Province(BK20170549)China Postdoctoral Science Foundation(2022M711381)。
文摘High-efficiency sodium-ion batteries(SIBs) are in great demand for energy storage applications,which are dominated by the Na+storage performance of electrode materials.Here,a one-pot solvothermal method is developed to construct amorphous/crystalline MoO_(2)(a/c-MoO_(2)) homojunction for boosting Na+storage.Theoretical simulations signify that electrons redistribute at the homogenous interface of a/c-MoO_(2),resulting in an inbuilt driving force to easily adsorb charge carriers and promote the electron/ion transfer ability.Relying on its crystallographic superiorities,the a/c-MoO_(2)homojunction with high Na adsorbability(-1.61 eV) and low Na diffusion energy barrier(0.519 eV) achieves higher capacity(307 mA h g^(-1)at 0.1 A/g),better rate capability and cycling stability than either a-MoO_(2)or c-MoO_(2)counterpart.Combining in-situ X-ray diffraction(XRD) and ex-situ X-ray photoelectron spectroscopy(XPS)techniques,the ’adsorption-insertion-conversion’ mechanism is well established for Na+storage of MoO_(2).Our work opens new opportunities to optimize electrode materials via crystallographic engineering for efficient Na+storage,and helps to better understand the effects of homojunction structure in enhanced electrochemical performance.
基金Singapore MOE Tier Ⅱ grant R143-000-A29-112the National Research Foundation under the Grant of NRF2017NRF-NSFC001-007.
文摘Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion of slovated Na+but allow the entrance of naked Na^(+) into the pores,which can reduce the interficial contact between the electrolyte and the inner pores without sacrificing the fast diffusion kinetics.Herein,a molten diffusion-carbonization method is proposed to transform the micropores(>1 nm)inside carbon into ultra-micropores(<0.5 nm).Consequently,the designed carbon anode displays an enhanced capacity of 346 mAh g^(−1) at 30 mA g^(−1) with a high ICE value of~80.6%and most of the capacity(~90%)is below 1 V.Moreover,the high-loading electrode(~19 mg cm^(−2))exhibits a good temperature endurance with a high areal capacity of 6.14 mAh cm^(−2) at 25℃ and 5.32 mAh cm^(−2) at −20℃.Based on the in situ X-ray diffraction and ex situ solid-state nuclear magnetic resonance results,the designed ultra-micropores provide the extra Na+storage sites,which mainly contributes to the enhanced capacity.This proposed strategy shows a good potential for the development of high-performance SIBs.
基金This work was supported by the National Natural Science Foundation of China(52071137,51977071,51802040,and 21802020)the Science and Technology Innovation Program of Hunan Province(2021RC3066 and 2021RC3067)+1 种基金the Natural Science Foundation of Hunan Province(2020JJ3004 and 2020JJ4192)N.Zhang and X.Xie also acknowledge the financial support of the Fundamental Research Funds for the Central Universities.
文摘Low-temperature assembly of MXene nanosheets into three-dimensional(3D) robust aerogels addresses the crucial stability concern of the nano-building blocks during the fabrication process,which is of key importance for transforming the fascinating properties at the nanoscale into the macroscopic scale for practical applications.Herein,suitable cross-linking agents(amino-propyltriethoxysilane,Mn^(2+),Fe^(2+),Zn^(2+),and Co^(2+)) as interfacial mediators to engineer the interlayer interactions are reported to realize the graphene oxide(GO)-assisted assembly of Ti_(3)C_(2)T_(x) MXene aerogel at room temperature.This elaborate aerogel construction not only suppresses the oxidation degradation of Ti_(3)C_(2)T_(x) but also generates porous aerogels with a high Ti_(3)C_(2)T_(x) content(87 wt%) and robustness,thereby guaranteeing the functional accessibility of Ti_(3)C_(2)T_(x) nanosheets and operational reliability as integrated functional materials.In combination with a further sulfur modification,the Ti_(3)C_(2)T_(x) aerogel electrode shows promising electrochemical performances as the freestanding anode for sodium-ion storage.Even at an ultrahigh loading mass of 12.3 mg cm^(-2),a pronounced areal capacity of 1.26 mAh cm^(-2) at a current density of 0.1 A g^(-1) has been achieved,which is of practical significance.This work conceptually suggests a new way to exert the utmost surface functionalities of MXenes in 3D monolithic form and can be an inspiring scaffold to promote the application of MXenes in different areas.
基金supported by the National Natural Science Foundation of China(51832004,51521001)the National Key Research and Development Program of China(2016YFA0202603)+2 种基金the Program of Introducing Talents of Discipline to Universities(B17034)the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)the “Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University。
文摘Sodium-ion storage devices are highly desirable for large-scale energy storage applications owing to the wide availability of sodium resources and low cost.Transition metal nitrides(TMNs)are promising anode materials for sodium-ion storage,while their detailed reaction mechanism remains unexplored.Herein,we synthesize the mesoporous Mo3N2 nanowires(Meso-Mo_(3)N_(2)-NWs).The sodium-ion storage mechanism of Mo3N2 is systematically investigated through in-situ XRD,ex-situ experimental characterizations and detailed kinetics analysis.Briefly,the Mo_(3)N_(2) undergoes a surface pseudocapacitive redox charge storage process.Benefiting from the rapid surface redox reaction,the Meso-Mo_(3)N_(2)-NWs anode delivers high specific capacity(282 m Ah g^(-1) at 0.1 A g^(-1)),excellent rate capability(87 m Ah g^(-1) at 16 A g^(-1))and long cycling stability(a capacity retention of 78.6%after 800 cycles at 1 A g^(-1)).The present work highlights that the surface pseudocapacitive sodium-ion storage mechanism enables to overcome the sluggish sodium-ion diffusion process,which opens a new direction to design and synthesize high-rate sodiumion storage materials.
基金supported by the Guangdong Natural Science Funds for Distinguished Young Scholar (2017B030306006)the National Natural Science Foundation of China (Nos. 51772164, U1601206 and U1710256)+2 种基金the National Key Basic Research Program of China (2014CB932400)the Shenzhen Technical Plan Project (Nos. KQJSCX20160226191136, JCYJ20150529164918734 and JCYJ20170412171630020)the Shenzhen Environmental Science and New Energy Technology Engineering Laboratory (No. SDRC [2016]172)
文摘Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish intercalation kinetics of sodium ions impedes the rate performance.Thus,the precise structure control of carbon materials is important to improve the battery performance.Herein,a 3D porous hard-soft composite carbon(3DHSC)was prepared using the NaCl as the template and phenolic resin and pitch as carbon precursors.The NaCl template restrains the growth of the graphite crystallite during the carbonization process,resulting in small graphitic domains with expanded interlayer spacing which is favorable for the sodium storage.Moreover,the Na Cl templates help to create abundant mesopores and macropores for fast sodium ion diffusion.The porous structure and the graphite crystalline structure can be precisely controlled by simply adjusting the mass ratio of Na Cl,and thus,the suitable structure can be prepared to reach high capacity and rate performance while keeping a relatively high Coulombic efficiency.Typically,a high reversible capacity(215 mA h g^(-1)at 0.05 A g^(-1)),an excellent rate capability(97 mA h g^(-1)at 5 A g^(-1)),and a high initial Coulombic efficiency(60%)are achieved.
基金financial support from the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. NSFC51621001)the Guangdong Special Support Program (2017TQ04N224)+1 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2017B030306004)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme。
文摘O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.
基金supported by the National Natural Science Foundation of China(Grant No.51872236)the Joint Fund ProjectEnterprise-Shaanxi Coal Joint Fund Project(2019JLM-32)。
文摘The large-scale application of sodium ion batteries(SIBs)is limited by economic and environmental factors.Here,we prepare multi-heteroatom self-doped hierarchical porous carbon(HHPC)with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor.As an anode for SIB,HHPC-1100 exhibits a capacity of 331.7 mA h g^(-1) at 20 mA g^(-1),while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping.Moreover,the synergistic effect of O,N,S,P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study,which provide a theoretical basis for the prominent electrochemical performance of the material.
基金support from the National Natural Science Foundation of China(51920105004,52102223)the Basic and Applied Basic Research Fund Project of Guangdong Province(2020A1515110401)。
文摘Tin selenide(SnSe)is considered as a potential anode for sodium-ion batteries(SIBs)owing to its high theoretical specific capacity.Unfortunately,it suffers from drastic volume expansion/contraction during sodium ions insertion/extraction,resulting in poor cycling stability.Herein,a pomegranate-inspired porous carbon shell wrapped heterogeneous SnSe/ZnSe composite(SnSe/ZnSe@C)is exquisitely designed and fabricated through electrostatic spraying followed by high-temperature selenization.The polyacrylonitrile-derived carbon shell acts as an adhesive to link the porous cubic SnSe/ZnSe and form highly interconnected microcircuits to improve the electron/ion transfer efficiency and inhibit the bulk volume change of internal metallic selenide nanoparticles and polyselenides dissolution during repeated cycling.Moreover,the abundant heterostructure interface of SnSe/ZnSe further significantly accelerates the electrons/ions transport.As a result,the as-prepared SnSe/ZnSe@C electrode exhibits a high specific capacity(508.3 m Ah g^(-1)at 0.05 A g^(-1)),excellent rate performance(177.8 m Ah g^(-1)at 10.0 A g^(-1)),and remarkable cycling stability(195.9 m Ah g^(-1)after 10,000 cycles at 5.0 A g^(-1)).Furthermore,in-situ Xray diffraction(XRD)/Raman,ex-situ transmission electron microscopy,and kinetic analysis clearly reveal a four-step electrochemical reaction process and battery-capacitor dual-mode sodium storage mechanism.This work provides a new perspective for developing commercial SIBs anode materials with high capacity and long lifespan.
基金support of the Office of Naval Research(ONR grant numbers N000141712244 and N000141912113)support from the National Key R&D Program of China(Grant Number:2016YFA0202602)+1 种基金Natural Science Foundation of Fujian Province of China“Double-First Class”Foundation of Materials and Intel igent Manufacturing Discipline of Xiamen University
文摘Sodium-ion battery materials and devices are promising candidates for largescale applications,owing to the abundance and low cost of sodium sources.Emerging sodium-ion pseudocapacitive materials provide one approach for achieving high capacity at high rates,but are currently not well understood.Herein,a comprehensive overview of the fundamentals and electrochemical behaviors of vanadium-based pseudocapacitive materials for sodium-ion storage is presented.The insight of sodium-ion storage mechanisms for various vanadium-based materials,including vanadium oxides,vanadates,vanadium sulfides,nitrides,and carbides are systematically discussed and summarized.In particular,areas for further development to improve fundamental understanding of electrochemical and structural properties of materials are identified.Finally,we provide a perspective on the application of pseudocapacitive materials in high-power and high-energy sodium-ion storage devices(e.g.,sodium-ion capacitors).
基金financially supported by the National Natural Science Foundation of China(21471040)。
文摘Rational electrode structure design is of great significance for realizing superior Na^(+)storage performance.Herein,a metal salt-induced polymer blowing-bubble approach followed by selenization procedure is developed to in-situ generate abundant sub-10 nm CoSe_(2) nanocrystals on 3D Se/N co-doped carbon networks(CoSe_(2)@3DSNC).The phase transition from Co to CoSe_(2) and the incorporation of Se into the carbon layer are realized simultaneously to establish above configuration,in which the CoSe_(2) nanocrystals are anchored on interlayer expanded carbon networks.Such unique configuration endows electrode with lower Na+diffusion energy barrier,higher Na+storage capability and better structural durability.Reflected in SIBs,the optimized CoSe_(2)@3 DSNC delivers superior rate capability(310 m Ah g^(-1) at 10 A g^(-1))and excellent longterm cycling stability(409 m Ah g^(-1) after 1200 cycles at 5 A g^(-1)).Moreover,this configuration can also be obtained in other metal selenides-carbon composite through a similar approach.
基金This work was financially supported by the National Natural Science Foundation of China(NSFC.U1904190,51925207,U1910210,52161145101 and 51872277)the Natural Science Foundation for Excellent Young Scholars of Henan Province(Grant No.212300410091)+5 种基金Program for Science and Technology Innovation Talents in Universities of Henan Province(Grant No.22HASTIT005)Key Program of Henan Province for Science and Technology(222102240029)the“Transformational Technologies for Clean Energy and Demonstration”Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA21000000)the National Synchrotron Radiation Laboratory(KY2060000173)the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(Grant.YLU-DNL Fund 2021002)the Fundamental Research Funds for the Central Universities(WK2060140026).
文摘The latest view suggests the inactive core,surface pulverization,and poly sulfide shuttling effect of metal sulfides are responsible for their low capacity and poor cycling performance in sodium-ion batteries(SIBs).Whereas overcoming the above problems based on conventional nanoengineering is not efficient enough.In this work,erythrocyte-like CuS microspheres with an elastic buffering layer of ultrathin poly aniline(PANI) were synthesized through one-step selfassembly growth,followed by in situ polymerization of aniline.When CuS@PANI is used as anode electrode in SIBs,it delivers high capacity,ultrahigh rate capability(500 mAh gat 0.1 A g,and 214.5 mAh gat 40 A g),and superior cycling life of over 7500 cycles at 20 A g.A series of in/ex situ characterization techniques were applied to investigate the structural evolution and sodium-ion storage mechanism.The PANI swollen with electrolyte can stabilize solid electrolyte interface layer,benefit the ion transport/charge transfer at the PANI/electrolyte interface,and restrain the size growth of Cu particles in confined space.Moreover,finite element analyses and density functional simulations confirm that the PANI film effectively buffers the volume expansion,suppresses the surface pulverization,and traps the poly sulfide.
基金supported by The Australian Research Council(ARC)under project FL170100101The University of Queensland for o ering UQI Scholarship
文摘Conversion-type anode materials with a high charge storage capability generally su er from large volume expansion, poor electron conductivity, and sluggish metal ion transport kinetics. The electrode material described in this paper, namely cobalt sulphide nanoparticles encapsulated in carbon cages(Co9S8@NC), can circumvent these problems. This electrode material exhibited a reversible sodium-ion storage capacity of 705 mAh g^-1 at 100 mA g^-1 with an extraordinary rate capability and good cycling stability. Mechanistic study using the in situ transmission electron microscope technique revealed that the volumetric expansion of the Co9S8 nanoparticles is bu ered by the carbon cages, enabling a stable electrode–electrolyte interface. In addition, the carbon shell with high-content doped nitrogen significantly enhances the electron conductivity of the Co9S8@NC electrode material and provides doping-induced active sites to accommodate sodium ions. By integrating the Co9S8@NC as negative electrode with a cellulose-derived porous hard carbon/graphene oxide composite as positive electrode and 1 M NaPF6 in diglyme as the electrolyte, the sodium-ion capacitor full cell can achieve energy densities of 101.4 and 45.8 Wh kg^-1 at power densities of 200 and 10,000 W kg^-1, respectively.
基金supported by the National Natural Science Foundation of China(Nos.U22A20107 and 22162026)the Science and Technology R&D Program Joint Fund Project of Henan Provincial(No.222301420001)+2 种基金the Distinguished Young Scholars Innovation Team of Zhengzhou University(No.32320275)Qiushi Scientific Research Initiation Plan of Zhengzhou University(No.32213243)Postgraduate Education Reform Project of Henan Province(No.2021SJGLX093Y).
文摘Rechargeable sodium-ion batteries(SIBs)are considered as the next-generation secondary batteries.The performance of SIB is determined by the behavior of its electrode surface and the electrode–electrolyte interface during charging and discharging.Thus,the characteristics of these surfaces and interfaces should be analyzed to realize large-scale energy storage systems with high energy density and long-cycle stability.Although various studies have investigated the properties of electrode materials,few studies have focused on the construction of stable and efficient SIB interfaces,and even fewer have explored the mechanisms of interfacial effects;however,the strategies of regulating interfacial effects are yet to be completely developed.Moreover,the results obtained thus far are insufficient to draw systematic conclusions.The present study reviews the literature on the mechanism of interfacial effects in Na+storage devices.The interfaces in a sodium-ion storage device include a heterogeneous interface between electrode materials,a solid electrolyte interphase,and a cathode electrolyte interphase.The interfacial effects during the intercalation,transformation,and alloy reactions and the resulting overall battery performance were theoretically analyzed.In this review,we aim to provide a theoretical basis for optimizing the structures of electrode surface and electrode–electrolyte interface to optimize the performance of SIBs.In addition,the challenges of investigating interfacial effects and several possible helpful methods and opportunities for studying the mechanisms of interfacial effects in SIBs will be presented.
基金financially supported by the National Natural Science Foundation of China (Nos.52072322 and 51604250)Sichuan Science and Technology Program (Nos.2022YFG0294 and 2019-GH02-00052-HZ)。
文摘Vanadium disulfide(VS_(2)) as a typical two-dimensional transition metal chalcogenide has excellent competitiveness for sodium-ion storage due to its wide layer spacing(0.575 nm),high theoretical capacity of 932mAh·g^(-1) originating from multi-electron electrochemical redox.However,continuous sodiation process accompanied by crystal structural evolution and collapse cause rapid capacity decaying.Herein,novel few-layer VS_(2)nanosheets with open(001) crystal planes are in-situ constructed on reduced graphene oxide to solve these issues mentioned above.It indicates that few-layer VS_(2)provides more Na^(+) storage activity due to the low Na^(+)surface migration energy barrier on exposed crystal(001)planes.The flexible and high electronic conductivity of carbon matrix also effectively builds multi-level buffer structure and electron transport kinetics to boost the Na^(+)insertion/conversion reactive activity on VS_(2) as well as Na^(+) pseudocapacitance storage kinetics on edges and defects of nano sheets.Those coupling effects result in high rate capability and long cycling stability as a battery/capacitor anode.It delivers conspicuous high energy density of 81 and 40 Wh·kg^(-1) at power density of 118 and 10,286W·kg^(-1),as well as 80% energy retention rate after 5000cycles,confirming its great application potential in sodiumbased storage devices.
基金supported by the National Key Research and Development Program of China(2022YFB3803400)the National Natural Science Foundation of China(22379028,22109028,52261135631 and 52103335)+2 种基金the Natural Science Foundation of Shanghai(22ZR1404400)the Chenguang Program sponsored by Shanghai Education Development FoundationShanghai Municipal Education Commission(19CG01)。
文摘Common evaluation methodology of sodium(Na)-containing two-electrode or three-electrode configurations overlooks the interference from highly reactive Na metal,leading to the underestimation or inconsistent performance of low-potential hard carbon(HC)electrodes.Herein,the trap of Na metal was systematically investigated with or without applied current,uncovering its inadequacy as the reference or counter electrode in different configurations.A Na-metal-free three-electrode protocol is proposed for evaluating the actual Na^(+)-storage capability of the typical low-potential HC electrode.By avoiding Na crosstalk and precisely controlling the working electrode's potential,the actual electrochemical performance of HC in the carbonate esterbased electrolyte can be recognized with high capacity of 222 mAh g^(-1)at 2 C and 113 mAh g^(-1)at 5 C,correcting the misunderstanding of the inferior performance of HC in coin-type half cells(68%and 50%undervaluation at 2 C and 5 C,respectively).The advanced protocol is expected to reduce misunderstandings or underestimation due to evaluation methods and to guide the development of high-performance battery materials.
基金financially supported by the National Natural Science Foundation of China(Nos.51603092 and 21706103)the Natural Science Foundation of Jiangsu Province(Nos.BK20160537 and BK20170549)China Postdoctoral Science Foundation(No.2019T120393)。
文摘Cobalt selenide(CoSe_(2))has become a promising anode material for sodium-ion batteries(SIBs)due to its stable chemical properties,environmental friendliness,and high theoretical capacity.However,the undesirable rate capacity and cycle stability of the anode materials largely limit its applications for SIBs due to the relatively low electronic conductivity and huge volume change during the Na+insertion/extraction.In this study,electrostatic spinning combined with a wet chemical method is employed to synthesize coral-like composite material(CNF@c-CoSe_(2)/C),which is composed of CoSe_(2)/carbon nanosheet arrays(CoSe_(2)/C)and carbon nanofibers(CNFs).CoSe_(2)/C nanoflakes derived from metal-organic frameworks(MOFs)with high surface area and the porous structure can inhibit the pulverization and amorphization of CoSe_(2) during charge and discharge processes,thus significantly keeping the stability of the microstructure.CNF can limit the overgrowth of nanosheets and serve as a conductive skeleton.Compared to two-dimensional CoSe_(2)/C nanoflakes and pure CoSe_(2) nanoparticles,the composite can expose more active sites and effectively accelerate the diffusion of Na+,which displays enhanced rate capability(266.5 mAh·g^(-1) at 5.0 A·g^(-1))and cycling stability(268.3 mAh·g^(-1) after 100 cycles at 1.0 A·g^(-1)).Moreover,the rational preparation strategy for metal selenide-based heterostructure material presents a new way for high-performance SIB s.
基金The authors acknowledge the financial support of this work by the National Natural Science Foundation of China(No.52202302)National Natural Science Foundation of Shaanxi(Nos.2019JLZ-01 and 2022KXJ-146)+1 种基金the Fundamental Research Funds for the Central Universities(No.3102019JC005)the Youth Innovation Team of Shaanxi Universities and ND Basic Research Funds(No.G2022WD).
文摘Benefiting from the distinctive ordering degree and local microstructure characteristics,hard carbon(HC)is considered as the most promising anode for sodium-ion batteries(SIBs).Unfortunately,the low initial Coulombic efficiency(ICE)and limited reversible capacity severely impede its extensive application.Here,a homogeneous curly graphene(CG)layer with a micropore structure on HC is designed and executed by a simple chemical vapor deposition method(without catalysts).CG not only improves the electronic/ionic conductivity of the hard carbon but also effectively shields its surface defects,enhancing its ICE.In particular,due to the spontaneous curling structural characteristics of CG sheets(CGs),the micropores(≤2 nm)formed provide additional active sites,increasing its capacity.When used as a sodium-ion battery anode,the HC-CG composite anode displayed an outstanding reversible capacity of 358 mAh·g^(-1),superior ICE of 88.6%,remarkable rate performance of 145.8 mAh·g^(-1)at 5 A·g^(-1),and long cycling life after 1000 cycles with 88.6%at 1 A·g^(-1).This work provides a simple defect/microstructure turning strategy for hard carbon anodes and deepens the understanding of Na+storage behavior in the plateau region,especially on the pore-filling mechanism by forming quasi-metallic clusters.
基金National Natural Science Foundation of China,Grant/Award Numbers:22005256,22179113Fundamental Research Funds for the Central Universities,Grant/Award Number:20720210045Natural Science Foundation of Fujian Province of China,Grant/Award Number:2020J01034。
文摘Vanadium nitride(VN)electrode displays high-rate,pseudocapacitive responses in aqueous electrolytes,however,it remains largely unclear in nonaqueous,Na+-based electrolytes.The traditional view supposes a conversion-type mechanism for Na+storage in VN anodes but does not explain the phenomena of their size-dependent specific capacities and underlying causes of pseudocapacitive charge storage behaviors.Herein,we insightfully reveal the VN anode exhibits a surface-redox pseudocapacitive mechanism in nonaqueous,Na+-based electrolytes,as demonstrated by kinetics analysis,experimental observations,and first-principles calculations.Through ex situ X-ray photoelectron spectroscopy and semiquantitative analyses,the Na+storage is characterized by redox reactions occurring with the V5+/V4+to V3+at the surface of VN particles,which is different from the well-known conversion reaction mechanism.The pseudocapacitive performance is enhanced through nanoarchitecture design via oxidized vanadium states at the surface.The optimized VN-10 nm anode delivers a sodium-ion storage capability of 106 mAh g−1 at the high specific current of 20 A g−1,and excellent cycling performance of 5000 cycles with negligible capacity losses.This work demonstrates the emerging opportunities of utilizing pseudocapacitive charge storage for realizing high-rate sodium-ion storage applications.