CoAl2O4包覆LiNi1/3Co1/3Mn1/3O2的电化学性能

通过共沉淀法制得类球形锂离子电池正极材料LiNi_1/3Co_1/3Mn_1/3O₂，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8 nm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%（by mass）CoAl₂O₄包覆量的LiNi1/3Co1/3Mn1/3O2材料（LNCMO(1)）高充电电压（3.0 ~ 4.6 V，150 mA·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 °C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.

Electrochemical Performance of CoAl2O4-Coated LiNi1/3Co1/3Mn1/3O2

A method to improve the electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂ for high voltage lithium-ion battery by CoAl₂O₄ coating was present in this work. The effects of CoAl₂O₄ coatings on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were investigated in detail. The results show that CoAl₂O₄ forms a thin layer of 8 nm on the surface of LiNi_1/3Co_1/3Mn_1/3O₂ without destroying the structure of the core material. The CoAl₂O₄-coated LiNi_1/3Co_1/3Mn_1/3O₂ possesses better rate capability and cycle performance than the uncoated sample. The excellent cycling performance can be obtained even with 1% (by mass) CoAl₂O₄ coating, for example, the capacity retentions at the 100th cycle increase from 74.4% to 93.7% at room temperature, and 17.7% to 77% at 55 °C, respectively. It was also confirmed that the CoAl₂O₄ coating could depress Mn ions dissolving into the electrolyte, and could lead to the enhancement in the structural stability and the thermal stability of LiNi_1/3Co_1/3Mn_1/3O₂, suggesting that the CoAl₂O₄ coating is an efficient way to improve the electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂.