Pyrochlore-structured polyantimonic acid(PAA)is a potential high-capacity electrode material,but its innately poor electroconductivity(~10^(-10)S/cm)seriously impairs its electrochemical reversibility for lithium-ion ...Pyrochlore-structured polyantimonic acid(PAA)is a potential high-capacity electrode material,but its innately poor electroconductivity(~10^(-10)S/cm)seriously impairs its electrochemical reversibility for lithium-ion storage.Herein,we report design and synthesis of a novel V-substituted PAA(PAA-V),where V^(5+)are introduced to partially replace Sb^(5+).Owing to identical valence and close ionic radius relative to Sb^(5+),the V^(5+)cation can constitute the covalent VO_6octahedra framework without changing the pyrochlore crystal structure of PAA.As a result,the V^(5+)-substitution is capable to modulate the electronic structure of PAA with significantly improved electrical conductivity(~10^(-6)S/cm for PAA-V)and meanwhile decreases the size of crystals with reduced diffusion length for Li^(+)-ions.With varying the ratio of V^(5+)-substitution,the PAA-V with optimized substitution molar ratio(18%)exhibits the best lithium-ion storage performance,delivering a long cycling life with high reversible capacity(731 m Ah/g after 1200cycles at 1 A/g)and outstanding rate capability(279 mAh/g at 15 A/g).More importantly,by pairing the PAA-V as anode and commercial LiFePO_(4)as cathode,the full cell with a limited negative/positive capacity ratio of 1.2 exhibits decent cycling stability at 1 C after 150 cycles with 85.5%capacity retention.展开更多
基金financial support from the National Natural Science Foundation of China(No.21878192)the Fundamental Research Funds for the Central Universities(No.2016SCU04A18)the 1000 Talents Program of Sichuan Province,and the Sichuan Province Science and Technology Support Program(No.2019YFG0221)。
文摘Pyrochlore-structured polyantimonic acid(PAA)is a potential high-capacity electrode material,but its innately poor electroconductivity(~10^(-10)S/cm)seriously impairs its electrochemical reversibility for lithium-ion storage.Herein,we report design and synthesis of a novel V-substituted PAA(PAA-V),where V^(5+)are introduced to partially replace Sb^(5+).Owing to identical valence and close ionic radius relative to Sb^(5+),the V^(5+)cation can constitute the covalent VO_6octahedra framework without changing the pyrochlore crystal structure of PAA.As a result,the V^(5+)-substitution is capable to modulate the electronic structure of PAA with significantly improved electrical conductivity(~10^(-6)S/cm for PAA-V)and meanwhile decreases the size of crystals with reduced diffusion length for Li^(+)-ions.With varying the ratio of V^(5+)-substitution,the PAA-V with optimized substitution molar ratio(18%)exhibits the best lithium-ion storage performance,delivering a long cycling life with high reversible capacity(731 m Ah/g after 1200cycles at 1 A/g)and outstanding rate capability(279 mAh/g at 15 A/g).More importantly,by pairing the PAA-V as anode and commercial LiFePO_(4)as cathode,the full cell with a limited negative/positive capacity ratio of 1.2 exhibits decent cycling stability at 1 C after 150 cycles with 85.5%capacity retention.
