Solvothermal Synthesis Of Li₃VO₄ Anode Material And Its Electrochemical Performance

As a new type of intercalation/deintercalation anode material,Li₃VO₄shows high energy density and high safety compared with commercial graphite and Li₄Ti₅O₁₂ anode materials,demonstrating great research and application value.However,it is a great challenge to tune the morphology of Li₃VO₄ owing to its strong hydrophilia,which results in unsatisfactory electrochemical performance.This paper aims to explore the synthesis of Li₃VO₄ via solvothermal method,and to improve the performance of Li₃VO₄ by combining it with conductive components.A mixed solution of ethylene glycol and deionized water（volume ratio1:1）was choosed as solvent,on the basis of preliminary experimental exploration.The main contents of this paper are as follows:Li₃VO₄ particles and Li₃VO₄/reduced graphene oxide（rGO）composite material was firstly synthesized via a solvent thermal approach at 90℃and atmosphere pressure.It is found that the introduction of graphene oxide not only effectively improves the conductivity of Li₃VO₄,but also inhibits the aggregation of Li₃VO₄ particles.As a result,the electronic conductivity and lithium ion diffusion of the Li₃VO₄/rGO are distinctly improved.The Li₃VO₄/rGO exhibits excellent electrochemical performance as anode for lithium ion batteries.When cycling at a specific current of 0.15 A g^-1,the Li₃VO₄/rGO delivers initial charge/discharge capacity of 500.5/751.3 m Ah g^-1.After 200 cycles,high discharge capacity of410.7 m Ah g^-1 is still remained.The facile and the normal-pressure synthesis is easy to scale up,which is beneficial to its practical use.Li₃VO₄/rGO composite material was successfully prepared under high-temperature and high-pressure solvothermal environment in an autocave.The electrochemical performance of the Li₃VO₄/rGO could be optimized by tuning the reaction temperature.The obtained Li₃VO₄/rGO composite shows initial charge/discharge capacity of 629.8/847 m Ah g^-1 at 0.15 A g^-1,maintaining of 522.9/526.5 m Ah g^-1 after 300 cycles.When increasing the current from0.15 to 0.3,0.75,1.5 and 1.5 m Ah g^-1,the discharge capacity decreases from 526.4 to 448.2,370.1,314.2 and 261.9 m Ah g^-1,respectively.After two periods of rate performance testing,the discharge capacity could revert to 486.1 m Ah g^-1,showing excellent stability.The synthesis and electrochemical performance optimization of Li₃VO₄ via solvothermal method provide a new approach for the design of high-performance Li₃VO₄ materials.Li₃VO₄-MXene/N composite material was successfully synthesized via a solvothermal environment by introducing MXene as conductive material and hexamethylenetetramine as the source for N doping.The MXene/N could significantly improve the charge transfer and lithium ion diffusion in the composite,inducing high pseudocapacitive charge storage and excellent electrochemical performance.The initial charge/discharge capacity of the Li₃VO₄-MXene/N composite is 535.8/797.3 m Ah g^-1 at 0.15 A g^-1,respectively.After 200 cycles,the charge/discharge capacity still retains of 463.8/465.3 m Ah g^-1.The high pseudocapacitance contribution caused by N-doped MXene provides a reference for the design of high-performance Li₃VO₄ anode materials.The excellent electrochemical performance of the Li₃VO₄-MXene/N makes it great potential in lithium-ion batteries.