### 铝掺杂及钨酸锂表面包覆双效提升富锂锰基正极材料的循环稳定性

1. 长安大学材料科学与工程学院 西安 710061
• 投稿日期:2020-07-16 发布日期:2020-10-12
• 通讯作者: 李东林 E-mail:dlli@chd.edu.cn
• 基金资助:
项目受国家自然科学基金面上项目（Nos.21473014，21073021）资助.

### Dual Effect of Aluminum Doping and Lithium Tungstate Coating on the Surface Improves the Cycling Stability of Lithium-rich Manganese-based Cathode Materials

Ren Xuqiang, Li Donglin, Zhao Zhenzhen, Chen Guangqi, Zhao Kun, Kong Xiangze, Li Tongxin

1. School of Materials Science and Engineering, Chang'an University, Xi'an 710061, China
• Received:2020-07-16 Published:2020-10-12
• Supported by:
Project supported by the National Natural Science Foundation of China (Nos. 21473014, 21073021).

The layered lithium-rich manganese-based cathode material has been widely concerned because of it's advantages such as a specific discharge capacity greater than 250 mAh·g-1 and a high discharge platform, and is expected to become the next-generation lithium ion battery cathode material. However, lithium-rich manganese-based cathode materials have poor cycle stability, low coulombic efficiency for the first charge and discharge, and low rate performance. The most important thing is that the problem of faster voltage decays on the discharge platform has not been effectively solved, The current it is mainly to improve the performance by element doping modification and surface coating, so it is very important to find suitable doping elements and coating materials. The common coating material is mainly to prevent direct contact between the electrolyte and the positive electrode material to improve the cycle stability, and it is difficult to slow down the attenuation of the discharge voltage platform. Al-doping lithium-rich manganese-based Li1.2Mn0.54-xAlxNi0.13Co0.13O2 (x=0, 0.03) cathode material was prepared by sol-gel method and Li2WO4 surface coating by one-step liquid phase method. The required materials were confirmed by X-ray diffractometer (XRD), energy disperse spectroscopy (EDS) and scanning electron microscope (SEM) tests, and then the effects of Al-doping and Li2WO4 coated double-effect modification on the electrochemical performance of lithium-rich manganese-based cathode materials were studied by electrochemical test system. The results show that Al doping significantly improves the cycling stability of lithium-rich manganese-based cathode materials, and the coating Li2WO4 significantly improves its rate performance and discharge platform voltage attenuation. In 5% Li2WO4 coated Li1.2Mn0.51Al0.03Ni0.13Co0.13O2 cathode material in charge and discharge voltage 2.0~4.8 V, and under the current density 1000 mA·g-1, the specific capacity is still as high as about 110 mAh·g-1. At the same time, the specific capacity retention rate was 78% after 300 cycles at the current density of 100 mA·g-1, and the voltage decay of the discharge platform significantly slowed down during the cycle.