While argyrodite sulfides are getting more and more attention as highly promising solid-state electrolytes(SSEs)for solid batteries,they also suffer from the typical sulfide setbacks such as poor electrochemical compa...While argyrodite sulfides are getting more and more attention as highly promising solid-state electrolytes(SSEs)for solid batteries,they also suffer from the typical sulfide setbacks such as poor electrochemical compatibility with Li anode and high-voltage cathodes and serious sensitivity to humid air,which hinders their practical applications.Herein,we have devised an effective strategy to overcome these challenging shortcomings through modification of chalcogen chemistry under the guidance of theoretical modeling.The resultant Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)delivered excellent electrochemical compatibility with both pure Li anode and high-voltage LiCoO_(2)cathode,without compromising the superb ionic conductivity of the pristine sulfide.Furthermore,the current SSE also exhibited highly improved stability to oxygen and humidity,with further advantage being more insulating to electrons.The remarkably enhanced compatibility with electrodes is attributed to in situ formation of helpful electrolyte–electrode interphases.The formation of in situ anode–electrolyte interphase(AEI)enabled stable Li plating/stripping in the Li|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li symmetric cells at a high current density up to 1 mA cm^(-2)over 200 h and 2 mA cm^(-2)for another 100 h.The in situ amorphous nano-film cathode–electrolyte interphase(CEI)facilitated protection of the SSE from decomposition at elevated voltage.Consequently,the synergistic effect of AEI and CEI helped the LiCoO_(2)|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li full-battery cell to achieve markedly better cycling stability than that using the pristine Li_(6)PS_(5)Cl as SSE,at a high area loading of the active cathode material(4 mg cm^(-2))in type-2032 coin cells.This work is to add a desirable SSE in the argyrodite sulfide family,so that high-performance solid battery cells could be fabricated without the usual need of strict control of the ambient atmosphere.展开更多
Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase ...Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase to the 1T phase has been proven to be a significant method to improve the catalytic activity.However,precisely controllable phase engineering of MoSe_(2) has rarely been reported.Herein,by in situ Li ions intercalation in MoSe_(2),a precisely controllable phase evolution from 2H-MoSe_(2) to 1T-MoSe_(2) was realized.More importantly,the definite functional relationship between cut-off voltage and phase structure was first identified for phase engineering through in situ observation and modulation methods.The sulfur host(CNFs/1T-MoSe_(2))presents high charge density,strong polysulfides adsorption,and catalytic kinetics.Moreover,Li-S cells based on it display capacity retention of 875.3mAh g^(-1) after 500 cycles at 1 C and an areal capacity of 8.71mAh cm^(-2) even at a high sulfur loading of 8.47mg cm^(-2).Furthermore,the flexible pouch cell exhibiting decent performance will endow a promising potential in the wearable energy storage field.This study proposes an effective strategy to precisely control the phase structure of MoSe_(2),which may provide the reference to fabricate the highly efficient electrocatalysts for LSBs and other energy systems.展开更多
Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered ...Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics;however,the unwanted side reaction at the anode hinders the practical application of SIBs.In this work,a precisely controlled Al_(2)O_(3)coated nitrogen doped vertical graphene nanosheets(NVG)anode material has been proposed,which exhibits excellent sodium storage capacity and cycling stability.The ultrathin Al_(2)O_(3)coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte,both alleviating the electrolyte decomposition and enhancing sodium adsorption ability.As a result,the optimal Al_(2)O_(3)coated NVG materials delivers a high reversible capacity(835.0 mAh g^(-1))and superior cycling stability(retention of 92.3%after 5000 cycles).This work demonstrates a new way to design graphene-based anode materials for highperformance sodium-ion batteries.展开更多
Transition metal oxide cathodes such as layered Li Co O_(2),spinel Li Mn_(2)O_(4) and olivine Li Fe PO4 have been commercialized for several decades and widely used in the rechargeable Li-ion batteries(LIBs).While gre...Transition metal oxide cathodes such as layered Li Co O_(2),spinel Li Mn_(2)O_(4) and olivine Li Fe PO4 have been commercialized for several decades and widely used in the rechargeable Li-ion batteries(LIBs).While great theoretical efforts have been made using the density functional theory(DFT)method,leading to insightful understanding covering materials stability and functional properties,the lack of consistency in choices of functionals and/or convergence criteria makes it somewhat difficult to compare results.It is therefore highly useful to assess these established systems towards self-consistency,thus offering a reliable working basis for theoretical formulation of novel cathodes.Here in this work,we have carried out systematic DFT calculations on the basis of recently established framework covering both thermodynamic stability,functional properties and associated mechanisms.Efforts have been made in selfconsistent selection of exchange-correlation(XC)functionals in terms of dependable accuracy with affordable computational cost,which is essential for high-throughput first-principles calculations.The outcome of the current work on three established cathode systems is in very good agreement with experimental data,and the methodology is to provide a solid basis for designing novel cathode materials without using costing non-local exchange-correlation functionals for structure-energy calculations.展开更多
To probe the coupling effect of the electron and Li ion conductivities in Ni-rich layered materials(LiNi0.8Co0.15Al0.05O2,NCA),lithium lanthanum titanate(LLTO)nanofiber and carbon-coated LLTO fiber(LLTO@C)materials we...To probe the coupling effect of the electron and Li ion conductivities in Ni-rich layered materials(LiNi0.8Co0.15Al0.05O2,NCA),lithium lanthanum titanate(LLTO)nanofiber and carbon-coated LLTO fiber(LLTO@C)materials were introduced to polyvinylidene difluoride in a cathode.The enhancement of the conductivity was indicated by the suppressed impedance and polarization.At 1 and 5 C,the cathodes with coupling conductive paths had a more stable cycling performance.The coupling mechanism was analyzed based on the chemical state and structure evolution of NCA after cycling for 200 cycles at 5 C.In the pristine cathode,the propagation of lattice damaged regions,which consist of high-density edge-dislocation walls,destroyed the bulk integrity of NCA.In addition,the formation of a rock-salt phase on the surface of NCA caused a capacity loss.In contrast,in the LLTO@C modified cathode,although the formation of dislocation-driven atomic lattice broken regions and cation mixing occurred,they were limited to a scale of several atoms,which retarded the generation of the rock-salt phase and resulted in a pre-eminent capacity retention.Only NiO phase“pitting”occurred.A mechanism based on the synergistic transport of Li ions and electrons was proposed.展开更多
The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed a...The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.展开更多
All-solid-state batteries(ASSB) with lithium anode have attracted ever-increasing attention towards developing safer batteries with high energy densities.While great advancement has been achieved in developing solid e...All-solid-state batteries(ASSB) with lithium anode have attracted ever-increasing attention towards developing safer batteries with high energy densities.While great advancement has been achieved in developing solid electrolytes(SE) with superb ionic conductivity rivalling that of the current liquid technology,it has yet been very difficult in their successful application to ASSBs with sustaining rate and cyclic performances.Here in this work,we have realized a stable ASSB using the Li_(6.25)PS_(5.25)Cl_(0.75) fast ionconducting electrolyte together with LiNbO_3 coated LiCoO_2 as cathode and lithium foil as the anode.The effective diffusion coefficient of Li-ions in the battery is higher than 10^(-12) cm~2 s^(-1),and the significantly enhanced electrochemical matching at the cathode-electrolyte interface was essential to enable long-term stability against high oxidation potential,with the LCO@LNO/Li_(6.25)PS_(5.25)Cl_(0.75)/Li battery to retain 74.12% capacity after 430 cycles at 100 μA cm-2 and 59.7% of capacity after 800 cycles at 50 μA cm^(-2),at a high charging cut-off voltage of 4.2 V.This demonstrates that the Li_(6.25)PS_(5.25)Cl_(0.75) can be an excellent electrolyte for the realization of stable ASSBs with high-voltage cathodes and metallic lithium as anode,once the electrochemical compatibility between cathode and electrolyte can be addressed with a suitable buffer coating.展开更多
All-inorganic CsPbBr_(3)-based perovskite solar cells(PSCs)have attracted great attention because of their high chemical and thermal stabilities in ambient air.However,the short-circuit current density(J_(sc))of CsPbB...All-inorganic CsPbBr_(3)-based perovskite solar cells(PSCs)have attracted great attention because of their high chemical and thermal stabilities in ambient air.However,the short-circuit current density(J_(sc))of CsPbBr_(3)-based PSCs is inadequate under solar illumination because of the wide bandgap,inefficient charge extraction and recombination loss,leading to lower power-conversion efficiencies(PCEs).It is envisaged that in addition to narrowing the bandgap by alloying,J_(sc)of the PSCs could be enhanced by effective improvement of electron transportation,suppression of charge recombination at the interface between the perovskite and electron transporting layer(ETL),and tuning of the space charge field in the device.In this work,Nb-doped SnO_(2)films as ETLs in the CsPbBr_(3)-based PSCs have been deposited at room temperature by high target utilization sputtering(Hi TUS).Through optimizing the Nb doping level alone,the J_(sc)was increased by nearly 19%,from 7.51 to 8.92 mA·cm^(-2)and the PCE was enhanced by 27%from 6.73%to 8.54%.The overall benefit by replacing the spin-coated SnO_(2)with sputtered SnO_(2)with Nb doping was up to 39%increase in J_(sc)and 62%increase in PCE.Moreover,the PCE of the optimized device showed negligible degradation over exposure to ambient environment(T~25°C,RH~45%),with 95.4%of the original PCE being maintained after storing the device for 1200 h.展开更多
The leakage of liquid electrolyte and the formation of lithium dendrites pose challenges to safety and stability of lithium metal batteries(LMBs).The appearance of gel polymer electrolyte(GPE)has obviously improved th...The leakage of liquid electrolyte and the formation of lithium dendrites pose challenges to safety and stability of lithium metal batteries(LMBs).The appearance of gel polymer electrolyte(GPE)has obviously improved the safety of traditional LMBs.However,the limited inhibition of GPE on lithium dendrites is detrimental to the safety of LMBs.Herein,a kind of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)/gelatin(GN)GPE with high ionic conductivity,high-temperature resistance,and flame-retardancy,was prepared by electrospinning and soaking method.Utilizing the electrospinning network of PVDF-HFP,its affinity to liquid electrolytes,makes this GPE more beneficial to ions transport and the formation of gel.And,the GN with sol–gel properties,enhances the mechanical property(13.5 MPa)of HFP-GN GPE.Meanwhile,X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)suggest that the attraction of polar groups of GN to Li+can regulate the distribution of Li+and protect Li anodes.Consequently,the application of HFP-GN GPEs to LMBs with cathodes of LiFePO_(4) and LiCoO_(2) deliver excellent electrochemical performances:after 300 cycles,the LiFePO_(4)/HFP-GN GPE/Li battery keeps a low capacity decay rate of 0.09%at 5 C;after 400 cycles at 2 C,the LiCoO_(2)/HFP-GN GPE/Li cell retains a high capacity retention of 74%.This GPE is demonstrated for the application prospect of safe LMBs.展开更多
The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active m...The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active materials and poor cycling efficiency.In this paper,the pore structures of carbon nanosheets based electrocatalysts were precisely controlled by regulating the content of water-soluble KCl template.The relationship between pore structures and Li-S electrochemical behavior was studied,which demonstrates a key influence of pore structure in polysulfides phase conversions.In the liquid-sloid redox reaction of polysulfides,the micropores and small mesopores(d<20 nm)exhibited little impact,while the meso-pores(d>20 nm)and macropores played a decisive role.As a typical exhibition,the nickel-embedded carbon nanosheets(Ni-CNS)with a high content of large mesopores and macropores can aid Li-S batteries in exhibiting stable cycling performance(760.1 mAh g^(-1)at 1 C after 300 cycles)and superior rate capac-ity(847.8 mAh g^(-1)at 2 C).Furthermore,even with high sulfur loading(8 mg cm^(−2))and low electrolyte(E/S is around 6μL mg^(-1)),the high area capacity of 7.7 mAh cm^(−2)at 0.05 C could be achieved.This work can provide a guideline for the design of the pore structure of carbon-based electrocatalysts toward high-efficiency sulfur species redox reactions,and afford a general,controllable,and simple approach to constructing high performance Li-S batteries.展开更多
The realistic application of lithium-sulfur(Li-S)batteries has been severely hindered by the sluggish conversion kinetics of polysulfides(LiPS)and inhomogeneous deposition of Li_(2)S at high sulfur loading and low ele...The realistic application of lithium-sulfur(Li-S)batteries has been severely hindered by the sluggish conversion kinetics of polysulfides(LiPS)and inhomogeneous deposition of Li_(2)S at high sulfur loading and low electrolyte/sulfur ratio(E/S).Herein,a flexible Li-S battery architecture based on electrocatalyzed cathodes made of interfacial engineered TiC nanofibers and in situ grown vertical graphene are developed.Integrated 1D/2D heterostructured electrocatalysts are realized to enable highly improved Li^(+)and electron transportation together with significantly enhanced affinity to LiPS,which effectively accelerate the conversion kinetics between sulfur species,and thus induce homogeneous deposition of Li_(2)S in the catalyzed cathodes.Consequently,highly active electro-electrocatalystsbased cells exhibit remarkable rate capability at 2C with a high specific capacity of 971 mAh g^(-1).Even at ultra-high sulfur loading and low E/S ratio,the battery still delivers a high areal capacity of 9.1 mAh cm^(-2),with a flexible pouch cell being demonstrated to power a LED array at different bending angles with a high capacity over 100 cycles.This work puts forward a novel pathway for the rational design of effective nanofiber electrocatalysts for cathodes of high-performance Li-S batteries.展开更多
Vertical graphene(VG),possessing superior chemical,physical,and structural peculiarities,holds great promise as a building block for constructing a high-energy density lithium-sulfur(Li-S)battery.Therefore,it is desir...Vertical graphene(VG),possessing superior chemical,physical,and structural peculiarities,holds great promise as a building block for constructing a high-energy density lithium-sulfur(Li-S)battery.Therefore,it is desirable to develop a new VG growth technique with a novel structure to enable wide applications.Herein,we devise a novel complex permittivity-dependent plasma confinement-assisted VG growth technique,via asymmetric growing a VG layer on one side of N-doped carbon nanofibers for the first time,using a unique lab-built high flux plasma-enhanced chemical vapor deposition system,as a bifunctional nanofiber membrane to construct Li-S batteries with low neg-ative/positive(N/P)and electrolyte/sulfur(E/S)ratios.The unique nanofiber membrane could simultaneously protect the cathode and anode,enabling an excellent electrochemical performance with low N/P and E/S ratios in Li-S bat-teries.Such a full cell delivers high gravimetric energy density and volumetric energy density of 340 Wh kg^(-1) and 547 Wh L^(-1),respectively,at low N/P(2:1)and E/S(4:1)ratios.Furthermore,a pouch cell achieves a high areal capacity of 7.1 mAh cm^(-2) at a sulfur loading of 6 mg cm^(-2).This work put forward a novel pathway for the design of high-energy density Li-S batteries.展开更多
Lithium(Li)metal is widely considered the ultimate anode for future rechargeable batteries.However,dendritic growth and related parasitic reactions during long-term cycling often lead to severe safety hazards and cata...Lithium(Li)metal is widely considered the ultimate anode for future rechargeable batteries.However,dendritic growth and related parasitic reactions during long-term cycling often lead to severe safety hazards and catastrophic failure.Herein,we fabricate a hybrid anode by coating single-phase Li_(21)Si_(5)on lithium metal.The resultant electrodes show a stable cycle and depressed polarization in symmetric and half cells.A planar plating/stripping behavior is observed on the modified anode.The investigation of the interplay of Li and Li_(21)Si_(5)shows relatively large adsorption energy in the Li-Si system.The deposition and stripping are surface processes,and Li_(21)Si_(5)maintains its intrinsic phase structure.The deposited Li layer around Li_(21)Si_(5)also has the advantage of diminished preferred orientation,which also contributes to the planar growth of Li.Both LiFePO4(LFP)and LiNi1/3Co1/3 Mn1/3O2(NCM)cathodes were applied to further demonstrate the enhanced rate and cycle performance.展开更多
基金supported in part by the Zhengzhou Materials Genome Institutethe National Natural Science Foundation of China(No.52171082,51001091,51571182,111174256,91233101,51602094,11274100)the Program for Science&Technology Innovation Talents in the Universities of Henan Province(18HASTIT009)。
文摘While argyrodite sulfides are getting more and more attention as highly promising solid-state electrolytes(SSEs)for solid batteries,they also suffer from the typical sulfide setbacks such as poor electrochemical compatibility with Li anode and high-voltage cathodes and serious sensitivity to humid air,which hinders their practical applications.Herein,we have devised an effective strategy to overcome these challenging shortcomings through modification of chalcogen chemistry under the guidance of theoretical modeling.The resultant Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)delivered excellent electrochemical compatibility with both pure Li anode and high-voltage LiCoO_(2)cathode,without compromising the superb ionic conductivity of the pristine sulfide.Furthermore,the current SSE also exhibited highly improved stability to oxygen and humidity,with further advantage being more insulating to electrons.The remarkably enhanced compatibility with electrodes is attributed to in situ formation of helpful electrolyte–electrode interphases.The formation of in situ anode–electrolyte interphase(AEI)enabled stable Li plating/stripping in the Li|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li symmetric cells at a high current density up to 1 mA cm^(-2)over 200 h and 2 mA cm^(-2)for another 100 h.The in situ amorphous nano-film cathode–electrolyte interphase(CEI)facilitated protection of the SSE from decomposition at elevated voltage.Consequently,the synergistic effect of AEI and CEI helped the LiCoO_(2)|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li full-battery cell to achieve markedly better cycling stability than that using the pristine Li_(6)PS_(5)Cl as SSE,at a high area loading of the active cathode material(4 mg cm^(-2))in type-2032 coin cells.This work is to add a desirable SSE in the argyrodite sulfide family,so that high-performance solid battery cells could be fabricated without the usual need of strict control of the ambient atmosphere.
基金National Natural Science Foundation of China,Grant/Award Numbers:U2004172,51972287 and 51502269the Foundation for University Key Teachers of Henan Province,Grant/Award Number:2020GGJS009Natural Science Foundation of Henan Province,Grant/Award Number:202300410368。
文摘Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase to the 1T phase has been proven to be a significant method to improve the catalytic activity.However,precisely controllable phase engineering of MoSe_(2) has rarely been reported.Herein,by in situ Li ions intercalation in MoSe_(2),a precisely controllable phase evolution from 2H-MoSe_(2) to 1T-MoSe_(2) was realized.More importantly,the definite functional relationship between cut-off voltage and phase structure was first identified for phase engineering through in situ observation and modulation methods.The sulfur host(CNFs/1T-MoSe_(2))presents high charge density,strong polysulfides adsorption,and catalytic kinetics.Moreover,Li-S cells based on it display capacity retention of 875.3mAh g^(-1) after 500 cycles at 1 C and an areal capacity of 8.71mAh cm^(-2) even at a high sulfur loading of 8.47mg cm^(-2).Furthermore,the flexible pouch cell exhibiting decent performance will endow a promising potential in the wearable energy storage field.This study proposes an effective strategy to precisely control the phase structure of MoSe_(2),which may provide the reference to fabricate the highly efficient electrocatalysts for LSBs and other energy systems.
基金supported by the National Natural Science Foundation of China(Nos.51602290,91233101,11174256)the Fundamental Research Program from the Ministry of Science and Technology of China(No.2014CB31704)Project funded by China Postdoctoral Science Foundation(No.2016M592310)。
文摘Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics;however,the unwanted side reaction at the anode hinders the practical application of SIBs.In this work,a precisely controlled Al_(2)O_(3)coated nitrogen doped vertical graphene nanosheets(NVG)anode material has been proposed,which exhibits excellent sodium storage capacity and cycling stability.The ultrathin Al_(2)O_(3)coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte,both alleviating the electrolyte decomposition and enhancing sodium adsorption ability.As a result,the optimal Al_(2)O_(3)coated NVG materials delivers a high reversible capacity(835.0 mAh g^(-1))and superior cycling stability(retention of 92.3%after 5000 cycles).This work demonstrates a new way to design graphene-based anode materials for highperformance sodium-ion batteries.
基金supported in part by the 1000 Talents Program of Chinathe Zhengzhou Materials Genome Institute+2 种基金the National Natural Science Foundation of China(No.51001091,51571182,111174256,91233101,51602094,11274100)the Fundamental Research Program from the Ministry of Science and Technology of China(No.2014CB931704)the Program for Science&Technology Innovation Talents in the Universities of Henan Province(18HASTIT009)。
文摘Transition metal oxide cathodes such as layered Li Co O_(2),spinel Li Mn_(2)O_(4) and olivine Li Fe PO4 have been commercialized for several decades and widely used in the rechargeable Li-ion batteries(LIBs).While great theoretical efforts have been made using the density functional theory(DFT)method,leading to insightful understanding covering materials stability and functional properties,the lack of consistency in choices of functionals and/or convergence criteria makes it somewhat difficult to compare results.It is therefore highly useful to assess these established systems towards self-consistency,thus offering a reliable working basis for theoretical formulation of novel cathodes.Here in this work,we have carried out systematic DFT calculations on the basis of recently established framework covering both thermodynamic stability,functional properties and associated mechanisms.Efforts have been made in selfconsistent selection of exchange-correlation(XC)functionals in terms of dependable accuracy with affordable computational cost,which is essential for high-throughput first-principles calculations.The outcome of the current work on three established cathode systems is in very good agreement with experimental data,and the methodology is to provide a solid basis for designing novel cathode materials without using costing non-local exchange-correlation functionals for structure-energy calculations.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51571182 and 51001091)the Fundamental Research Program from the Ministry of Science and Technology of China(No.2014CB931704)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(No.21IRTSTHN003).This work was also partially supported by the Provincial Scientific Research Program of Henan(No.182102310815).
文摘To probe the coupling effect of the electron and Li ion conductivities in Ni-rich layered materials(LiNi0.8Co0.15Al0.05O2,NCA),lithium lanthanum titanate(LLTO)nanofiber and carbon-coated LLTO fiber(LLTO@C)materials were introduced to polyvinylidene difluoride in a cathode.The enhancement of the conductivity was indicated by the suppressed impedance and polarization.At 1 and 5 C,the cathodes with coupling conductive paths had a more stable cycling performance.The coupling mechanism was analyzed based on the chemical state and structure evolution of NCA after cycling for 200 cycles at 5 C.In the pristine cathode,the propagation of lattice damaged regions,which consist of high-density edge-dislocation walls,destroyed the bulk integrity of NCA.In addition,the formation of a rock-salt phase on the surface of NCA caused a capacity loss.In contrast,in the LLTO@C modified cathode,although the formation of dislocation-driven atomic lattice broken regions and cation mixing occurred,they were limited to a scale of several atoms,which retarded the generation of the rock-salt phase and resulted in a pre-eminent capacity retention.Only NiO phase“pitting”occurred.A mechanism based on the synergistic transport of Li ions and electrons was proposed.
基金funded by the Zhengzhou Materials Genome Institute,the National Talents Program of China,and Key Innovation Projects of the Zhengzhou Municipal City of China.
文摘The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.
基金supported in part by the 1000 Talents Program of China, the Zhengzhou Materials Genome Institute (ZMGI)the Natural Science Foundation of China (Nos. 51001091, 91233101)the Fundamental Research Program from the Ministry of Science and Technology of China (no. 2014CB931704)。
文摘All-solid-state batteries(ASSB) with lithium anode have attracted ever-increasing attention towards developing safer batteries with high energy densities.While great advancement has been achieved in developing solid electrolytes(SE) with superb ionic conductivity rivalling that of the current liquid technology,it has yet been very difficult in their successful application to ASSBs with sustaining rate and cyclic performances.Here in this work,we have realized a stable ASSB using the Li_(6.25)PS_(5.25)Cl_(0.75) fast ionconducting electrolyte together with LiNbO_3 coated LiCoO_2 as cathode and lithium foil as the anode.The effective diffusion coefficient of Li-ions in the battery is higher than 10^(-12) cm~2 s^(-1),and the significantly enhanced electrochemical matching at the cathode-electrolyte interface was essential to enable long-term stability against high oxidation potential,with the LCO@LNO/Li_(6.25)PS_(5.25)Cl_(0.75)/Li battery to retain 74.12% capacity after 430 cycles at 100 μA cm-2 and 59.7% of capacity after 800 cycles at 50 μA cm^(-2),at a high charging cut-off voltage of 4.2 V.This demonstrates that the Li_(6.25)PS_(5.25)Cl_(0.75) can be an excellent electrolyte for the realization of stable ASSBs with high-voltage cathodes and metallic lithium as anode,once the electrochemical compatibility between cathode and electrolyte can be addressed with a suitable buffer coating.
基金supported by the National Natural Science Foundation of China(Nos.51602290,91233101,11174256)the Fundamental Research Program from the Ministry of Science and Technology of China(No.2014CB31704)+4 种基金Project funded by China Postdoctoral Science Foundation(No.2016M592310)the financial support from EPSRC New Investigator Award(2018EP/R043272/1)H2020-EU grant(2018CORNET 760949)
文摘All-inorganic CsPbBr_(3)-based perovskite solar cells(PSCs)have attracted great attention because of their high chemical and thermal stabilities in ambient air.However,the short-circuit current density(J_(sc))of CsPbBr_(3)-based PSCs is inadequate under solar illumination because of the wide bandgap,inefficient charge extraction and recombination loss,leading to lower power-conversion efficiencies(PCEs).It is envisaged that in addition to narrowing the bandgap by alloying,J_(sc)of the PSCs could be enhanced by effective improvement of electron transportation,suppression of charge recombination at the interface between the perovskite and electron transporting layer(ETL),and tuning of the space charge field in the device.In this work,Nb-doped SnO_(2)films as ETLs in the CsPbBr_(3)-based PSCs have been deposited at room temperature by high target utilization sputtering(Hi TUS).Through optimizing the Nb doping level alone,the J_(sc)was increased by nearly 19%,from 7.51 to 8.92 mA·cm^(-2)and the PCE was enhanced by 27%from 6.73%to 8.54%.The overall benefit by replacing the spin-coated SnO_(2)with sputtered SnO_(2)with Nb doping was up to 39%increase in J_(sc)and 62%increase in PCE.Moreover,the PCE of the optimized device showed negligible degradation over exposure to ambient environment(T~25°C,RH~45%),with 95.4%of the original PCE being maintained after storing the device for 1200 h.
基金supported by the National Natural Science Foundation of China(Nos.51502269,51972287,and U2004172)Natural Science Foundation of Henan Province(Nos.202300410368 and 222301420039)+1 种基金the Foundation for University Key Teachers of Henan Province(No.2020GGJS009)sponsored by Program for Science&Technology Innovation Talents in Universities of Henan Province(No.23HASTIT001).
文摘The leakage of liquid electrolyte and the formation of lithium dendrites pose challenges to safety and stability of lithium metal batteries(LMBs).The appearance of gel polymer electrolyte(GPE)has obviously improved the safety of traditional LMBs.However,the limited inhibition of GPE on lithium dendrites is detrimental to the safety of LMBs.Herein,a kind of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)/gelatin(GN)GPE with high ionic conductivity,high-temperature resistance,and flame-retardancy,was prepared by electrospinning and soaking method.Utilizing the electrospinning network of PVDF-HFP,its affinity to liquid electrolytes,makes this GPE more beneficial to ions transport and the formation of gel.And,the GN with sol–gel properties,enhances the mechanical property(13.5 MPa)of HFP-GN GPE.Meanwhile,X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)suggest that the attraction of polar groups of GN to Li+can regulate the distribution of Li+and protect Li anodes.Consequently,the application of HFP-GN GPEs to LMBs with cathodes of LiFePO_(4) and LiCoO_(2) deliver excellent electrochemical performances:after 300 cycles,the LiFePO_(4)/HFP-GN GPE/Li battery keeps a low capacity decay rate of 0.09%at 5 C;after 400 cycles at 2 C,the LiCoO_(2)/HFP-GN GPE/Li cell retains a high capacity retention of 74%.This GPE is demonstrated for the application prospect of safe LMBs.
基金supported by the National Natu-ral Science Foundation of China(Nos.U2004172,51972287)the National Natural Science Foundation of Henan Province(Nos.202300410368,222301420039)+2 种基金the Foundation for University Key Teacher of Henan Province(No.2020GGJS009)the Science&Technology Innovation Talents in Universities of Henan Province(No.23HASTIT001)the China Postdoctoral Science Foundation(No.2021M692898).
文摘The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active materials and poor cycling efficiency.In this paper,the pore structures of carbon nanosheets based electrocatalysts were precisely controlled by regulating the content of water-soluble KCl template.The relationship between pore structures and Li-S electrochemical behavior was studied,which demonstrates a key influence of pore structure in polysulfides phase conversions.In the liquid-sloid redox reaction of polysulfides,the micropores and small mesopores(d<20 nm)exhibited little impact,while the meso-pores(d>20 nm)and macropores played a decisive role.As a typical exhibition,the nickel-embedded carbon nanosheets(Ni-CNS)with a high content of large mesopores and macropores can aid Li-S batteries in exhibiting stable cycling performance(760.1 mAh g^(-1)at 1 C after 300 cycles)and superior rate capac-ity(847.8 mAh g^(-1)at 2 C).Furthermore,even with high sulfur loading(8 mg cm^(−2))and low electrolyte(E/S is around 6μL mg^(-1)),the high area capacity of 7.7 mAh cm^(−2)at 0.05 C could be achieved.This work can provide a guideline for the design of the pore structure of carbon-based electrocatalysts toward high-efficiency sulfur species redox reactions,and afford a general,controllable,and simple approach to constructing high performance Li-S batteries.
基金Foundation for University Key Teachers of Henan Province,Grant/Award Number:2020GGJS009National Natural Science Foundation of China,Grant/Award Numbers:U2004172,51972287,51502269Natural Science Foundation of Henan Province,Grant/Award Number:202300410368。
文摘The realistic application of lithium-sulfur(Li-S)batteries has been severely hindered by the sluggish conversion kinetics of polysulfides(LiPS)and inhomogeneous deposition of Li_(2)S at high sulfur loading and low electrolyte/sulfur ratio(E/S).Herein,a flexible Li-S battery architecture based on electrocatalyzed cathodes made of interfacial engineered TiC nanofibers and in situ grown vertical graphene are developed.Integrated 1D/2D heterostructured electrocatalysts are realized to enable highly improved Li^(+)and electron transportation together with significantly enhanced affinity to LiPS,which effectively accelerate the conversion kinetics between sulfur species,and thus induce homogeneous deposition of Li_(2)S in the catalyzed cathodes.Consequently,highly active electro-electrocatalystsbased cells exhibit remarkable rate capability at 2C with a high specific capacity of 971 mAh g^(-1).Even at ultra-high sulfur loading and low E/S ratio,the battery still delivers a high areal capacity of 9.1 mAh cm^(-2),with a flexible pouch cell being demonstrated to power a LED array at different bending angles with a high capacity over 100 cycles.This work puts forward a novel pathway for the rational design of effective nanofiber electrocatalysts for cathodes of high-performance Li-S batteries.
基金National Natural Science Foundation of China,Grant/Award Numbers:51972287,U2004172,51502269Foundation for University Key Teachers of Henan Province,Grant/Award Number:2020GGJS009Natural Science Foundation of Henan Province,Grant/Award Number:202300410368。
文摘Vertical graphene(VG),possessing superior chemical,physical,and structural peculiarities,holds great promise as a building block for constructing a high-energy density lithium-sulfur(Li-S)battery.Therefore,it is desirable to develop a new VG growth technique with a novel structure to enable wide applications.Herein,we devise a novel complex permittivity-dependent plasma confinement-assisted VG growth technique,via asymmetric growing a VG layer on one side of N-doped carbon nanofibers for the first time,using a unique lab-built high flux plasma-enhanced chemical vapor deposition system,as a bifunctional nanofiber membrane to construct Li-S batteries with low neg-ative/positive(N/P)and electrolyte/sulfur(E/S)ratios.The unique nanofiber membrane could simultaneously protect the cathode and anode,enabling an excellent electrochemical performance with low N/P and E/S ratios in Li-S bat-teries.Such a full cell delivers high gravimetric energy density and volumetric energy density of 340 Wh kg^(-1) and 547 Wh L^(-1),respectively,at low N/P(2:1)and E/S(4:1)ratios.Furthermore,a pouch cell achieves a high areal capacity of 7.1 mAh cm^(-2) at a sulfur loading of 6 mg cm^(-2).This work put forward a novel pathway for the design of high-energy density Li-S batteries.
基金the National Natural Science Foundation of China(Nos.51571182 and 51001091)the Fundamental Research Program from the Ministry of Science and Technology of China(No.2014CB931704)+1 种基金the Program for Science&Technology Innovation Talents in Universities of Henan Province(No.18HASTIT009)partially the Provincial Scientific Research Program of Henan(Nos.2017GGJS001 and 172102410023)。
文摘Lithium(Li)metal is widely considered the ultimate anode for future rechargeable batteries.However,dendritic growth and related parasitic reactions during long-term cycling often lead to severe safety hazards and catastrophic failure.Herein,we fabricate a hybrid anode by coating single-phase Li_(21)Si_(5)on lithium metal.The resultant electrodes show a stable cycle and depressed polarization in symmetric and half cells.A planar plating/stripping behavior is observed on the modified anode.The investigation of the interplay of Li and Li_(21)Si_(5)shows relatively large adsorption energy in the Li-Si system.The deposition and stripping are surface processes,and Li_(21)Si_(5)maintains its intrinsic phase structure.The deposited Li layer around Li_(21)Si_(5)also has the advantage of diminished preferred orientation,which also contributes to the planar growth of Li.Both LiFePO4(LFP)and LiNi1/3Co1/3 Mn1/3O2(NCM)cathodes were applied to further demonstrate the enhanced rate and cycle performance.
