控制结晶法合成球形正极材料LiNi_(0.8)Co_(0.2)O_2及其电化学性能

Synthesize and properties of spherical cathode materials LiNi_(0.8)Co_(0.2)O_2 by controlled crystallization method

采用控制结晶法制备锂离子电池用高密度球形正极材料LiNi0.8Co0.2O2。对前驱体Ni0.8Co0．2（OH）2制备工艺进行优化，在金属盐溶液流速为8mL／min，搅拌速率450r／min，pH值为11.5，氨浓度20g／L反应36h的条件下，合成了振实密度为2．02g／cm^3的球形Ni0．8Co0.2（OH）2。并以Ni0.8Co0.2（OH）2为原料，与LiOH·H2O进行混合研磨进行高温烧结，考察烧结制度对合成材料LiNi0.8Co0.2O2电化学性能的影响。在Li／（Ni＋Co）配比为1.05、氧气流量为800mL／min，750℃下烧结16h所得材料LiNi0.8Co0.2O2电化学性能最优：在0．2C，3．0-4．3V的条件下，首次放电容量达到195．4mA·h/g，循环50次后容量保持率达到89．2％。

High-density spherical cathode material LiNi0.8Co0.2O2 powders for lithium secondary battery were prepared via a controlled crystallization method. Under the preparation conditions, when metal salt solution flow rate was 8 mL/min, stirring speed was 450 r/min, pH value was 11.5, ammonia concentration was 20 g/L and reaction time was 36 h, the spherical Ni0.8Co0.2（OH）2 powders with tap-density of 2.02 g/cm^3 were obtained. The mixture of Ni0.8Co0.2（OH）2 and LiOH-H2O was sintered and the calcination process, especially sintering time and sintering temperature, was studied. LiNi0.8Co0.2O2cathode material, which is synthesized with 1.05 Li/（Ni＋Co） under 800 mL/min oxygen flow and 750 ℃ for 16 h, achieves a high initial discharge capacity of 195.4 mA·h/g at 0.2 C current between 3.0 and 4.3 V, and excellent capacity retention of 89,2% after 50 cycles.