Preparation And Electrochemical Performance Of Deintercalation Vanadium-based Lithium Storage Anode Material

Lithium-ion batteries（LIBs）has been successfully developed in a variety of electronic device fields and continues to be used in electric vehicles and other applications.However,lithium-ion batteries for electric vehicles have problems of low energy/power density,low safety and high cost,especially,the heat generation under high temperature conditions will cause material aging and energy/power density attenuation,and excessive Li⁺insertion will produce large internal stress,resulting in severe particle cracking and rapid capacity attenuation.At present,the intercalation-type vanadium based anode materials can not meet the demand for high performance at different temperatures.Therefore,we will further develop high-performance lithium ion storage materials with useful value.（1）K₂Sr V₄O₁₂（KSVO）nanowires with an average diameter of 200 nm were prepared by electrospinning and calcined at low temperature,which were used as new intercalation-type vanadium-based anode material.Firstly,the KSVO nanowire material has a large theoretical capacity of 381 m Ah g^-1(V⁵⁺（?）V³⁺)and proper working potential（～0.8 V）.In addition,KSVO nanowires have a special structure surrounded by an electrochemically active VO₄tetrahedral layer by an inactive KO₆/Sr O₈polyhedral layer,resulting in a"zero-strain"behavior with superior volume buffering capacity,making the unit-cell-volume change（up to 0.42%at 60℃）negligible.Consequently,KSVO nanowires retain 135.4%capacity at 60℃even after 1000 cycles of current at 4 A g^-1.This demonstrates superior cycle stability.In addition,KSVO materials exhibit better reversible capacity and magnification properties at room temperature and high temperature.（2）First,V₂O₅nanowires were prepared by electrospinning,and then lithium was chemically embedded in argon atmosphere with butyl lithium as the lithium reagent.Li_xV₂O₅（2<x<4）nanowires were successfully prepared as intercalation-type vanadium-based anode material by controlling the amount of lithium intercalation by adjusting the time.The mechanism of electrochemical reaction at different temperatures,crystal structure evolution and“zero-strain”mechanism were studied by means of electrochemical experiment with variable temperature,ex-situ XPS and ex-situ HRTEM.The experimental data show that the electrochemical performance of Li_3.05V₂O₅（LVO）nanowires is different with different time of lithium intercalation,and the electrochemical performance at room temperature of LVO nanowires obtained with lithium intercalation for 1h is the outstanding(a large reversible capacity of 576 m Ah g^-1at 0.05A g^-1;108%capacity retention over 2000 cycles at 10 A g^-1).LVO nanowires have more significant rate performance and excellent long cycle performance at high temperature(a larger reversible capacity of 658 m Ah g^-1at 0.05 A g^-1;108%capacity retention over 1000cycles at 10 A g^-1).Both topics show that lithium ion anode materials can have superior rate performance and long cycle stability at room temperature and high temperature,which provides a new development potential for future exploration of high-performance lithium ion battery anode materials.