【摘要】 以PVDF为碳源,采用溶胶凝胶法制备Li1.2Mn0.54Ni0.13Co0.13O2/C正极复合材料.利用X-射线衍射(XRD)、同步热分析、扫描电子显微镜(SEM)表征合成材料的结构,利用充放电测试、循环伏安及交流阻抗测试系统地研究了碳包覆对材料电化学性能的影响.研究表明,合成的材料具有a-Na Fe O2层状结构且碳均匀包覆在Li1.2Mn0.54Ni0.13Co0.13O2颗粒表面.相比于Li1.2Mn0.54Ni0.13Co0.13O2,Li1.2Mn0.54Ni0.13Co0.13O2/C表现出更好的倍率性能和循环稳定性.电化学性能测试表明,碳表面修饰层增强了活性材料颗粒之间的电导性能,有效缓解电解液中HF对活性材料的腐蚀,降低电荷跃迁电阻(Rct),从而有效提高了材料的电化学性能.更多还原

【Abstract】 Li1.2Mn0.54Ni0.13Co0.13O2/C cathode materials were successfully prepared by sol-gel method with PVDF ascarbon sources. The structural properties of the synthesized composites were characterized with XRD, STA andSEM techniques. The effects of carbon-coating on the electrochemical performances were investigated systemati-cally by charge-discharge test, cyclic voltammetry(CV), and AC impedance, respectively. The obtained resultsshow that the as-prepared powder has α-Na Fe O2 layered structure and that the carbon particles are uniformlydeposited on Li1.2Mn0.54Ni0.13Co0.13O2 surface. In comparison with Li1.2Mn0.54Ni0.13Co0.13O2,Li1.2Mn0.54Ni0.13Co0.13O2/C dem-onstrates higher rate performances and better cyclic reversibility. The analysis of electrochemical measurementsreveals that carbon layer will enhance the electronic conductivity between active material particles, protect effec-tively active materials from HF attack in the Li PF6 based electrolyte, reduce the charge transfer resistance(Rct)and consequently improve electrochemical performances.更多还原