Polarization behavior of lithium-rich manganese-based cathode materials at different temperatures

Abstract

Lithium-rich manganese-based cathode material is a promising next-generation lithium-ion battery cathode material, however, it exhibits significant differences in electrochemical performance at different temperatures, which severely limits the application in practical environments. A variety of electrochemical measures were used to characterize the difference in electrochemical performance of lithium-rich material within the temperature range of 5-45℃. The influencing factors of material properties and temperature dependence were analyzed from the perspective of polarization. The results show that the charge/discharge capacity of lithium-rich material decreases with decreasing temperature, which is mainly due to the significant increase in the polarization of the oxygen/manganese ion reaction in the high-voltage and low-voltage ranges with decreasing temperature, resulting in a severe decrease in its capacity contribution.The significantly increased polarization is mainly caused by the poor intrinsic kinetic performance of oxygen/manganese ions, which leading to high apparent activation energy of the charge transfer process. In addition, the participation of oxygen and manganese ions in the charge compensation reaction changes the structure of the material seriously.It induces changes in the composition of the interface film, which increases the apparent activation energy of lithium ion transmission at the interface in the low voltage interval. Moreover, it causes bulk diffusion of lithium ions at the end of the charge and discharge process having higher apparent activation energy. Therefore, improving the oxygen/manganese ion reaction kinetics of lithium-rich material is the main method to enhance its environmental adaptability.

Keywords

• lithium ion battery
• lithium-rich manganese-based cathode material
• electrochemical performance
• polarization characteristic
• temperature dependence