磷表面包覆正极材料LiCoO2及其电化学性能研究

通过低温固相法制备了单质磷表面包覆LiCoO2超细粉体,研究了不同包覆量对LiCoO2粉体物理性能和电化学性能的影响。通过XRD、SEM研究了晶体结构、形貌等。分析表明包覆的粉体具有层状结构,表面光滑,粉体分布均匀,粒径分布在0.2~0.6μm之间。充放电循环测试表明:与LiCoO2相比,包覆磷后电压平台略有下降;当单质磷包覆量为5%时,正极材料LiCoO2的初始容量为173.3 mAh.g-1,50个循环后容量为143.2 mAh.g-1;在0.5C倍率下,正极材料LiCoO2初始容量144.0 mAh.g-1,100次循环后容量118.3 mAh.g-1,平均每次容量损失为0.18%。

Study on Electrochemical Performance of Phosphorus-coating LiCoO2

Phosphorus-coated LiCoO2 ultrafine powder was synthesized by low-temperature solid-phase method. The effects of the phosphorus content on the physics and electrochemical performance of LiCoO2 were investigated. The materials were characterized by XRD and SEM, and it was found that the ultrafine powder has layered structure, smooth surface, uniform distribution, with particle size between 0. 2 - 0. 6 μm. Charge-discharge cycle test showed that： compared with LiCoO2, phosphorus coated LiCoO2 has a slight decreased voltage platform. At 0. 2 C , the initial discharge capacity of phosphorus-coated LiCoO2 is 173. 3 mAh·g^-1 and discharge capacity after 50 cycles is 143.1 mAh·g^-1. At 0. 5 C,the initial discharge capacity is 144. 0 mAh·g^-1 and discharge capacity after 100 cycles is 118.3 mAh ·g^-1, the average loss for each cycle is 0. 18 %.