Comparative Study on the Thermal Characteristics of Solid-State Lithium-Ion Batteries

Battery temperature greatly affects its electrical performance and safety. In this work, the thermal characteristics of a hybrid solid–liquid battery (referred to as a solid-state battery) were systematically studied for the development of future battery thermal management systems (BTMSs). The battery resistance characteristics were investigated by performing electrochemical impedance spectroscopy (EIS) measurements. Then, the extracted outcomes were connected with the heat generation and used to explain the trends of the battery thermal characteristics at different temperatures and current rates. Moreover, the resistance and thermal characteristics of the solid-state battery were compared to those of the traditional LiNiMnCoO2 (NMC) and LiFePO4 (LFP) batteries with similar capacities. According to the results, the solid-state battery has a bigger polarization resistance than the traditional batteries because of the larger charge transfer impedance and impedance across the film evoked by the solid electrolyte. The higher resistance makes the solid-state battery generate more heat and achieve a higher temperature rise, and a BTMS with stronger cooling performance is required. Moreover, the battery temperature rise plateau of the solid-state battery is mainly affected by the reversible heat, and the polarization heat is the biggest contributor to the total heat generation in the solid-state battery.