With graphite currently leading as the most viable anode for potassium-ion batteries(KIBs),other materials have been left relatively underexamined.Transition metal oxides are among these,with many positive attributes ...With graphite currently leading as the most viable anode for potassium-ion batteries(KIBs),other materials have been left relatively underexamined.Transition metal oxides are among these,with many positive attributes such as synthetic maturity,longterm cycling stability and fast redox kinetics.Therefore,to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5(KTNO)and its rGO nanocomposite(KTNO/rGO)synthesised via solvothermal methods as a high-performance anode for KIBs.Through effective distribution across the electrically conductive rGO,the electrochemical performance of the KTNO nanoparticles was enhanced.The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g^(−1) and reversible capacity of 97.5 mAh g^(−1) after 500 cycles at 20 mA g^(−1),retaining 76.1%of the initial capacity,with an exceptional rate performance of 54.2 mAh g^(−1)at 1 A g^(−1).Furthermore,to investigate the attributes of KTNO in-situ XRD was performed,indicating a low-strain material.Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage,with the titanium showing greater redox reversibility than the niobium.This work suggests this lowstrain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.展开更多
Solid-state lithium-metal batteries based on poly(vinylidene fluoride-co-hexafluoropropylene)(PVH)are frequently proposed to address the detrimental safety issue of conventional lithium-ion batteries by eliminating th...Solid-state lithium-metal batteries based on poly(vinylidene fluoride-co-hexafluoropropylene)(PVH)are frequently proposed to address the detrimental safety issue of conventional lithium-ion batteries by eliminating the use of flammable solvents,but still face a key challenge:low capacity and sluggish charge/discharge rate due to the intrinsic large-gradient Li^(+)distribution across the ionically-inert PVH matrix.Herein,Te vacancies in form of Bi_(2)Te_(3-x) are proposed to polarize the PVH unit to realize efficient decoupling of lithium salts at the atomic level in PVH-based solid polymeric electrolyte.Te vacancies in the PVH electrolyte doped with Bi_(2)Te_(3-x)(PVBT)induce a high-throughput and homogenous Li^(+)flow within the PVH matrices and near the Li metal.Theoretical calculations show that Te vacancies own high adsorption energy with bis(trifluoromethanesulfonyl)imide anions(TFSI^(-)),repulsive effect on Li^(+),and localized electron distribution,giving rise to a lithium-ion concentration gradient of 30 mol m^(-3),the smallest among the PVH-based inorganic/organic composite electrolytes.Consequently,the polarized electrolyte owns an unprecedented high-rate battery capacity of 114 mAh g^(-1)at~700 mA g^(-1)and also superior capacity performances with a cathode loading of 12 mg cm^(-2),outperforming the state-of-art PVH-based inorganic/organic composite electrolytes in Li||LiFePO_(4)battery.The work demonstrates an efficient strategy for achieving fast Liþdiffusion dynamics across polymeric matrices of classic solid-state electrolytes.展开更多
1.INTRODUCTION The rapid research progression in metal batteries(MBs)highlights the importance of metal anodes,the most energy-dense choice among all anodes.Metal anodes involve alkali metals(Li,Na,and K)1 and multiva...1.INTRODUCTION The rapid research progression in metal batteries(MBs)highlights the importance of metal anodes,the most energy-dense choice among all anodes.Metal anodes involve alkali metals(Li,Na,and K)1 and multivalent metals(Mg,Ca,Zn,and Al),2 and they are usually utilized in the form of metal foils.However,the practical application of metal anodes is accompanied by notorious challenges such as safety risks induced by metal dendrite growth,low Coulombic efficiency(CE)caused by parasitic reactions and“dead metal”,unstable solid electrolyte interphase(SEI),and low utilization of metal anodes due to their excessive thicknesses.展开更多
Rough Li plating,low ionic conductivity,and low thermal stability of conventional electrolytes post-primary challenges for achieving reliable high-capacity rechargeable lithium batteries,for which lithiummetal is freq...Rough Li plating,low ionic conductivity,and low thermal stability of conventional electrolytes post-primary challenges for achieving reliable high-capacity rechargeable lithium batteries,for which lithiummetal is frequently proposed as themost promising anode material.Conventional low-polarity commercial polypropylene/polyethylene separators fail to support the application of high-energy-density Li anodes due to their rigid physicochemical properties and the high reactivity of Li metal,leading to fatal dendrite formation and vigorous exothermic reaction with electrolytes.Herein,we develop a Li-wetting,flame-retardant binary polymer electrolyte by functionalizing poly(vinylidene fluoride)(PVDF)separators with nonflammable polybenzimidazole(PBI)to build safe room-temperature solid-state electrolyte membranes.A dendrite-free LiFePO4 cell with the solid polymer electrolyte(SPE)delivers a discharge capacity of 127 mAh g^(-1) at 25℃ with a capacity retention of 87.5%after 500 cycles at 0.5℃(0.15 mA cm^(-2)).Phase-field simulations and density functional theory calculations demonstrate that the negatively charged benzimidazole chains of PBI own superior affinity to lithium bis(trifluoromethanesulfonyl)imide(LiTFSI),and shares overlapping electron density with Li anode,giving rise to accelerated Li^(+)conduction at room temperature and uniform Li electrodeposition at the electrolyte/Li metal interface.The SPE is also flame-retardant since heat-resistant polytetrafluoroethylene and a dense,heat-blocking graphitized carbon layer are formed in intense heat throughdehydrogenation/fluorination of PVDF under the catalysis of Lewis base imidazole rings and the decomposition of benzimidazole rings in PBI.No such fire-resistant mechanism is ever reported in conventional electrolytes.展开更多
基金Y.X.acknowledges the financial support of the Engineering and Physical Sciences Research Council(EP/X000087/1,EP/V000152/1)Leverhulme Trust(RPG-2021-138)Royal Society(IEC\NSFC\223016).
文摘With graphite currently leading as the most viable anode for potassium-ion batteries(KIBs),other materials have been left relatively underexamined.Transition metal oxides are among these,with many positive attributes such as synthetic maturity,longterm cycling stability and fast redox kinetics.Therefore,to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5(KTNO)and its rGO nanocomposite(KTNO/rGO)synthesised via solvothermal methods as a high-performance anode for KIBs.Through effective distribution across the electrically conductive rGO,the electrochemical performance of the KTNO nanoparticles was enhanced.The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g^(−1) and reversible capacity of 97.5 mAh g^(−1) after 500 cycles at 20 mA g^(−1),retaining 76.1%of the initial capacity,with an exceptional rate performance of 54.2 mAh g^(−1)at 1 A g^(−1).Furthermore,to investigate the attributes of KTNO in-situ XRD was performed,indicating a low-strain material.Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage,with the titanium showing greater redox reversibility than the niobium.This work suggests this lowstrain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.
基金supported by Chongqing Technology Innovation and Application Development Special Key Project,CSTB2023TIAD-KPX0010Chongqing Technology Innovation and Application Development Special Major Project,CSTB2023TIAD-STX0033+1 种基金Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX0246,CSTB2022NSCQ-MSX1572,CSTB2022NSCQ-MSX0310)the Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environments.
文摘Solid-state lithium-metal batteries based on poly(vinylidene fluoride-co-hexafluoropropylene)(PVH)are frequently proposed to address the detrimental safety issue of conventional lithium-ion batteries by eliminating the use of flammable solvents,but still face a key challenge:low capacity and sluggish charge/discharge rate due to the intrinsic large-gradient Li^(+)distribution across the ionically-inert PVH matrix.Herein,Te vacancies in form of Bi_(2)Te_(3-x) are proposed to polarize the PVH unit to realize efficient decoupling of lithium salts at the atomic level in PVH-based solid polymeric electrolyte.Te vacancies in the PVH electrolyte doped with Bi_(2)Te_(3-x)(PVBT)induce a high-throughput and homogenous Li^(+)flow within the PVH matrices and near the Li metal.Theoretical calculations show that Te vacancies own high adsorption energy with bis(trifluoromethanesulfonyl)imide anions(TFSI^(-)),repulsive effect on Li^(+),and localized electron distribution,giving rise to a lithium-ion concentration gradient of 30 mol m^(-3),the smallest among the PVH-based inorganic/organic composite electrolytes.Consequently,the polarized electrolyte owns an unprecedented high-rate battery capacity of 114 mAh g^(-1)at~700 mA g^(-1)and also superior capacity performances with a cathode loading of 12 mg cm^(-2),outperforming the state-of-art PVH-based inorganic/organic composite electrolytes in Li||LiFePO_(4)battery.The work demonstrates an efficient strategy for achieving fast Liþdiffusion dynamics across polymeric matrices of classic solid-state electrolytes.
基金the financial support of the Engineering and Physical Sciences Research Council(EP/X000087/1,EP/V000152/1)Leverhulme Trust(RPG-2021-138)+1 种基金Royal Society(IEC\NSFC\223016)Science and Technology Facilities Council Batteries Network(ST/R006873/1).
文摘1.INTRODUCTION The rapid research progression in metal batteries(MBs)highlights the importance of metal anodes,the most energy-dense choice among all anodes.Metal anodes involve alkali metals(Li,Na,and K)1 and multivalent metals(Mg,Ca,Zn,and Al),2 and they are usually utilized in the form of metal foils.However,the practical application of metal anodes is accompanied by notorious challenges such as safety risks induced by metal dendrite growth,low Coulombic efficiency(CE)caused by parasitic reactions and“dead metal”,unstable solid electrolyte interphase(SEI),and low utilization of metal anodes due to their excessive thicknesses.
基金Applied Fundamental Research Fund of Sichuan Province,Grant/Award Number:2019YJ0169Fundamental Research Funds for the Chinese Central Universities,Grant/Award Number:ZYGX2015Z003+1 种基金Natural Science Foundation of China,Grant/Award Number:51972043Science&Technology Support Funds of Sichuan Province,Grant/Award Number:2016GZ0151。
文摘Rough Li plating,low ionic conductivity,and low thermal stability of conventional electrolytes post-primary challenges for achieving reliable high-capacity rechargeable lithium batteries,for which lithiummetal is frequently proposed as themost promising anode material.Conventional low-polarity commercial polypropylene/polyethylene separators fail to support the application of high-energy-density Li anodes due to their rigid physicochemical properties and the high reactivity of Li metal,leading to fatal dendrite formation and vigorous exothermic reaction with electrolytes.Herein,we develop a Li-wetting,flame-retardant binary polymer electrolyte by functionalizing poly(vinylidene fluoride)(PVDF)separators with nonflammable polybenzimidazole(PBI)to build safe room-temperature solid-state electrolyte membranes.A dendrite-free LiFePO4 cell with the solid polymer electrolyte(SPE)delivers a discharge capacity of 127 mAh g^(-1) at 25℃ with a capacity retention of 87.5%after 500 cycles at 0.5℃(0.15 mA cm^(-2)).Phase-field simulations and density functional theory calculations demonstrate that the negatively charged benzimidazole chains of PBI own superior affinity to lithium bis(trifluoromethanesulfonyl)imide(LiTFSI),and shares overlapping electron density with Li anode,giving rise to accelerated Li^(+)conduction at room temperature and uniform Li electrodeposition at the electrolyte/Li metal interface.The SPE is also flame-retardant since heat-resistant polytetrafluoroethylene and a dense,heat-blocking graphitized carbon layer are formed in intense heat throughdehydrogenation/fluorination of PVDF under the catalysis of Lewis base imidazole rings and the decomposition of benzimidazole rings in PBI.No such fire-resistant mechanism is ever reported in conventional electrolytes.
