烧结温度对共沉淀法合成LiNi_(0.8)Co_(0.2)O_2电化学性能的影响

采用并流共沉淀法制备了前驱体Ni0.8Co0.2(OH)2,然后采用高温固相反应法制备了锂离子电池正极材料LiNi0.8Co0.2O2,通过热重分析(TG)、X射线衍射(XRD)、扫描电子显微镜(SEM)与恒流充放电测试等研究了烧结温度对所制备材料物相结构、微观形貌和电化学性能的影响。结果表明,在卧式管式炉中空气气氛下进行两段控温烧结:第一段烧结温度为700℃,第二段烧结温度为750℃时,合成的LiNi0.8Co0.2O2具有良好的六方晶系α-NaFeO2层状结构;在0.5C充放电倍率下和2.7-4.3 V电压范围内,其首次放电比容量为153.0 mAh/g,20次循环后的容量保持率高达98.5%。

Effects of sintering temperature on electrochemical properties of LiNi0.8Co0.2O2 synthesized by co-precipitation method

The precursor Ni0.8Co0.2(OH)2 was prepared by the concurrent co-precipitation method,then cathode material LiNi0.8Co0.2O2 for Li-ion batteries was synthesized by high temperature solid state reaction method.Effects of sintering temperature on the structures,surface morphology and electrochemical properties of the prepared material were investigated through TG analysis,XRD,SEM and constant current charge/discharge test,etc.The results demonstrate that the LiNi0.8Co0.2O2 sintered firstly at 700 ℃,secondly at 750 ℃ in air atmosphere in tubular furnace possesses a good hexagonal α-NaFeO2 layer structure,at the 0.5C rate and in the 2.7–4.3 V,its initial discharge specific capacity is 153.0 mAh/g,and the capacity retention reaches 98.5% after 20 cycles.