Vanadium-site multivalent cation doping strategy of fluorophosphate cathode for low self-discharge sodium-ion batteries  

作　　者：Xinyuan Wang Qian Wang Jiakai Zhang Yuanzhen Ma Miao Huang Xiaojie Liu 

机构地区：[1]Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education,College of Chemistry&Materials Science,Northwest University,Xi'an 710127,Shaanxi,China

出　　处：《Journal of Energy Chemistry》2025年第3期365-376,共12页能源化学(英文版)

基　　金：supported by the National Natural Science Foundation of China(22075227);the Shaanxi Fundamental Science Research Project for Chemistry and Biology(23JHQ011)。

摘　　要：Na_(3)V_(2)O_(2x)(PO_(4))_(2)F_(3-2x)(NVPOF)is considered one of the most promising cathode materials for sodium-ion batteries due to its favorable working potential and optimal theoretical specific capacity.However,its long-cycle and rate performance are significantly constrained by the low Na^(+)electronic conductivity of NVPOF.Furthermore,the prevalent self-discharge phenomenon restricts its applicability in practical applications.In this paper,the cathode material Na_(3)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(x=0.16)was synthesized by quantitatively introducing Fe^(3+)into the V-site of NVPOF.The introduction of Fe^(3+)significantly reduced the original bandgap and the energy barrier of NVPOF,as demonstrated through density functional theory calculations(DFT).When material x=0.16 is employed as the cathode material for the sodium-ion battery,the Na^(+)diffusion coefficient is significantly enhanced,exhibiting a lower activation energy of42.93 kJ mol^(-1).Consequently,material x=0.16 exhibits excellent electrochemical performance(rate capacity:57.32 mA h g^(-1)@10 C,cycling capacity:the specific capacity of 101.3 mA h g^(-1)can be stably maintained after 1000 cycles at 1 C current density).It can also achieve a full charge state in only2.39 min at a current density of 10 C while maintaining low energy loss across various stringent self-discharge tests.In addition,the sodium storage mechanism associated with the three-phase transition of Na_(X)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(X=1,2,3)was elucidated by a series of experiments.In conclusion,this study presents a novel approach to multifunctional advanced sodium-ion battery cathode materials.

关 键 词：Multivalent cation doping V-site doping Fe^(3+)doping SELF-DISCHARGE Fluorophosphate cathode Sodium-ion batteries 

分 类 号：TM912[电气工程—电力电子与电力传动]