Preparation and Improvement of Electrochemical Performance of LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> Cathode Materials In Situ Coated with AlPO<sub>4</sub>
Xiaolong Bi, Longjiao Chang, Shiyuan Cao, Shaohua Luo, Wei Yang, Anlu Wei, Ruifen Yang, Jianan Liu
Abstract
In order to reduce the corrosion of LiNi 0.5 Mn 1.5 O 4 by an electrolyte, an innovative method of in situ coating of AlPO 4 was proposed in this paper, which effectively improved the high-temperature cycling performance of the electrode. The effects of AlPO 4 coating with different mass fractions on the structure, morphology, and electrochemical properties of LiNi 0.5 Mn 1.5 O 4 were investigated. Through analysis and testing, it is found that each coating amount has no obvious effect on the spinel structure of the material. When the coating content is 1.0%, the sample has higher capacity, better rate performance, and excellent cycle stability at a high temperature (55 °C). It is also found from the data of the alternating current impedance test that the Li + diffusion of the material is the most favorable when the coating amount is 1.0%, and the capacity retention rate reaches about 90% after 50 cycles at a 1 C rate. The results show that compared with the traditional coating method, the AlPO 4 coating layer of the LiNi 0.5 Mn 1.5 O 4 material obtained by in situ coating is more uniform (the layer thickness is about 4.2 nm), which more effectively blocks the contact between the LiNi 0.5 Mn 1.5 O 4 electrode and electrolyte, reduces the erosion of the electrolyte to LiNi 0.5 Mn 1.5 O 4, inhibits the oxygen loss in the material, and is more conducive to lithium-ion diffusion.