Synthesis And Electrochemical Performance Characterization Of Li-ion Batteries Cathode Material Li_1+xV₃O₈

Comparing with traditional lithium-ion battery cathode material such as LiCoO₂,LiMn2O4, etc.LiV₃O₈ has a high discharge capacity, inexpensive, and it's easy to synthesize. However, as LiV₃O₈ has some disadvantages such as more than two discharge platform, cycling performance is not good enough, etc. difficulties in applying still remain. In this paper, we prepared LiV₃O₈ cathode materials through sol-gel method, solid-state method, and doped LiV₃O₈ cathode materials to improve specific capacity and good cycle performance.The conventional high temperature synthesis of LiV₃O₈ undergoes a melting procedure, its products have low capacity, and difficult to control the proportion of lithium and vanadium, what's more, there exists post-processing problems. So gradually attention has been paid on low-temperature liquid phase method due to it's low temperature, low power consumption.In this paper, with LiNO3 and NH4VO3 as raw materials, we prepared LiV₃O₈ by sol-gel method, investigated morphology and electrochemical properties of the products through X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge test, cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS) experiments.Microwave sintering technology has many advantages such as sintering temperature can be controlled, sintering time is short, heating efficiency is high, security, pollution-free, etc.this technology has been used for synthesis of LiFePO4, LiMn2O4 and so on, but there is very little research on microwave sintering technology in the field of LiV₃O₈ materials. In this article, we prepared LiV₃O₈ by sol-gel method and treat it by microwave, studied the effects of after-microwave treatment on the structure, morphology and electrochemical properties of LiV₃O₈ synthesized by sol-gel method.Comparing with other methods, solid state reaction method is the simplest one and most easy for industrillisation. In this paper, with Li2CO3 and V2O5 as raw materials, we synthesized Li_1+xV₃O₈ material by solid state reaction method at moderate heating temperature which is below the melt temperature of LiV₃O₈ .effects of heating temperature and heating time were studied and the best sintering condition was designed.under the best sintering condition, we synthesized Li1+ xV3O8 material and researched its structure and electrochemical properties.To improve the electrochemical properties of Li_1+xV₃O₈ cathode material synthesized by solid state reaction method at moderate-heating temperature, this paper synthesized Ti⁴⁺-doped Li_1+xV₃O₈ with Rutile nano-TiO₂ as Ti source, F-- doped Li_1+xV₃O₈ with LiF as F source ,and finally prepared Ti-F complex doped Li_1+xV₃O₈ material with rutile nano-TiO₂ as Ti source, LiF as F source espectively. By XRD, SEM, charge-discharge test, CV test and EIS tests, we studied the effects of doping on the structure, morphology and electrochemical properties of Li_1+xV₃O₈ cathode material synthesized by solid state reaction method at moderate-heating temperature. The results show that doping, especially anion-cation complex doping, can effectively reduce the crystallization of Li_1+xV₃O₈ material,increace the capacity of the material, improve the charge-discharge performance and cycle performance of Li_1+xV₃O₈; Reducing the electrochemical impedance, enhanced the structural stability.