CoAl_2O_4包覆LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的电化学性能

Electrochemical Performance of CoAl_2O_4-Coated LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

通过共沉淀法制得类球形锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2，并用非水相共沉法对其进行CoAl2O4包覆得到LNCMO（x）．采用x射线衍射（XRD）、扫描电子显微术（SEM）和透射电子显微术（TEM）测试材料的结构和观察材料形貌．结果表明．CoAl2O4在材料表面形成8nm均匀包覆层，未改变主体材料的结构．电化学性能测试表明，1％（bymass）CoAl204包覆量的LiNi1/3Co1/3Mn1/3O2材料（LNCMO（1））高充电电压（3．0～4．6V，150mA·g^-1）100周期循环放电容量保持率为93．7％（无包覆LNCMO（0）保持率为74．4％）；55℃高温100周期循环容量保持率为77％（无包覆LNCMO（0）保持率17％）．XRD和电感耦合等离子体原子发射光谱（ICP—AES）测试表明，CoAl2O4包覆的LNCMO（x）材料可有效地减缓材料中Mn离子在电解液的溶解，提高材料结构稳定性和热稳定性．

A method to improve the electrochemical performance of Li Ni1/3Co1/3Mn1/3O2 for high voltage lithium-ion battery by Co Al2O4 coating was present in this work. The effects of Co Al2O4 coatings on the structure and electrochemical properties of Li Ni1/3Co1/3Mn1/3O2 were investigated in detail. The results show that Co Al2O4 forms a thin layer of 8 nm on the surface of Li Ni1/3Co1/3Mn1/3O2 without destroying the structure of the core material. The Co Al2O4-coated Li Ni1/3Co1/3Mn1/3O2 possesses better rate capability and cycle performance than the uncoated sample. The excellent cycling performance can be obtained even with1%（by mass） Co Al2O4 coating, for example, the capacity retentions at the 100 th cycle increase from 74.4% to 93.7% at room temperature, and 17.7% to 77% at 55 oC, respectively. It was also confirmed that the Co Al2O4 coating could depress Mn ions dissolving into the electrolyte, and could lead to the enhancement in the structural stability and the thermal stability of Li Ni1/3Co1/3Mn1/3O2, suggesting that the Co Al2O4 coating is an efficient way to improve the electrochemical performance of Li Ni1/3Co1/3Mn1/3O2.