Thermal-electrochemical behaviors of LiMn2O4 lithium-ion cell studied by electrochemical–calorimetric method

Abstract

Electrochemical–calorimetric measurements were adopted to investigate the thermal-electrochemical behaviors of LiMn2O4/Li CR2025 button cell during charge–discharge process with various rates at 313.15K. The results showed that the polarization and irreversibility of LiMn2O4 cell would be aggravated with the increasing of charge–discharge rate. X-ray diffraction (XRD) indicated that the crystal structure of the cathode material, LiMn2O4, was partially destroyed by side reaction at high rate (1.0C, 2.0C), producing the impurities of Li2MnO3 and MnO2. These impurities induced electrochemical performance degradation of battery. From the heat flow curves of the charge process, heat exothermic and endothermic process were found at low rates 0.1C. However, only exothermic process was observed when the rate increased from 0.2C to 2.0C. The enthalpy change was increased with the increasing of charge–discharge rate. These results revealed that the choosing of suitable charge–discharge rate is critical to the thermal management during the charge–discharge process of LiMn2O4/Li CR2025 button cell.