Multifactor Effects on the Thermal Performances of Molten-Salt Solid-State Lithium-Ion Batteries: A Numerical Study

摘要

The molten-salt battery is a very suitable battery for large-scale energy storage due to its low cost and excellent performance. A solid electrolyte-based liquid lithium battery (called SELL battery) is a new type of molten-salt battery with enormous potential for stationary energy storage and extreme environment energy storage such as aerospace and deserts. It has a series of advantages, including the good thermal and chemical performance of the LLZTO electrolyte, lithium anode’s high theoretical specific capacity (3860 mA h g~(–1)), and recharged high-capacity cathode material. For more stable operation and higher energy utilization efficiency of molten-salt batteries, we designed a thermal–electrochemical coupled 3D SELL battery module model. We successfully realized the module-level long-term (dozens of hours) transient simulation under different operating conditions. Results demonstrate the existence of an optimal charge–discharge rate, which minimizes the sum of the heat generated by the battery and heating plate (31% energy saving compared to battery standing). The heating plate’s variable power working mode is more flexible and effective than the constant power working mode. With the increasing thickness of the heat insulation board, energy consumption gradually reduces (energy consumption of which the thickness of heat insulation board equals 3 cm is 3.7 times that of a 12 cm one) and tends to be gentle. A dense array of batteries helps maintain battery temperature and different heating plate shapes have little effect on the average heating plate power. This paper successfully simulated the electrochemical and heat transfer processes of the SELL battery for the first time. It provided a general and efficient numerical simulation method for the molten-salt battery. The results obtained are conducive to improving the molten-salt battery’s stability and reducing the battery module’s energy consumption.