【摘要】 以聚乙二醇(PEG)作为还原剂和碳源,采用流变相法成功合成碳包覆的单斜晶系磷酸钒锂正极材料,采用XRD、SEM和电化学性能测试手段考察不同相对分子质量组合的聚乙二醇对合成材料的影响。SEM观察显示,大相对分子质量和小相对分子质量的聚乙二醇组合有利于合成更小、更均匀的颗粒。相对分子质量为200和20k组合的聚乙二醇合成的磷酸钒锂在0.1C,3.0~4.2 V电压范围进行充放电循环,其首次放电比容量为131.1 mA·h/g,30次循环后仍有123.6 mA·h/g,优于其他相对分子质量组合形式。通过CV和EIS图谱分析,相对分子质量相差越大,越有利于提高锂离子扩散系数,从而改善材料的电化学性能。更多还原

【Abstract】 The carbon-coated monoclinic Li3V2(PO4)3(LVP) cathode materials were successfully synthesized by liquid phase method using PEG as reducing agent and carbon source. The effects of relative molecular mass of PEG on the properties of Li3V2(PO4)3/C were evaluated by X-ray diffraction(XRD), scanning electron microscope(SEM) and electrochemical performance tests. The SEM images show that smaller size particles are obtained by adding larger and smaller PEGs. The electrochemical cycling of Li3V2(PO4)3/C prepared by both PEG200 and PEG20 k has a high initial discharge capacity of 131.1 mA·h/g at 0.1C during 3.0-4.2 V, and delivers a reversible discharge capacity of 123.6 m A·h/g over 30 cycles, which is better than that of other samples. The improvement in electrochemical performance is caused by its improved lithium ion diffusion coefficient for the macroporous morphology, which is verified by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).更多还原