Modeling the effect of cathode thickness on the low-temperature discharge behavior of all-solid-state thin-film lithium-ion batteries

All-solid-state thin-film lithium-ion batteries (ATLBs) are considered to be a promising energy storage power source due to their high safety and energy density. However, the limited lithium-ion conduction at low temperatures seriously hinders the performance of the battery. The cathode thickness influences the length of the lithium-ion diffusion path, which in turn affects the low-temperature performance of ATLBs. In order to enhance the low-temperature performance of ATLBs to meet the practical requirements, an advanced two-dimensional numerical model is established based on the electrochemical-thermal coupling model. The model considers the influence of lithium-ion concentration along the cathode thickness on its diffusion coefficient, and its effectiveness and accuracy are verified by comparing the simulation results with the experimental data. Then, this work discusses the low-temperature performance of ATLBs and its potential influencing mechanism in detail, and deeply analyzes the influence law of cathode thickness on the low-temperature performance of ATLBs. It is found that the discharge time increases by 125 s as the cathode thickness decreases from 320 nm to 240 nm at an extremely low temperature of 253.15 K, with an approximate increase of 6.08 %. Correspondingly, the capacity utilization also increases from 86.98 % to 92.26 %. This work provides theoretical guidance for the performance optimization and cathode thickness design of ATLBs at low temperatures. • The accuracy of the ATLB electrochemical-thermal coupling model is improved. • Thin cathode has a relative lower lithium-ion concentrations polarization. • The increase in discharge time can be up to 6.08 % at 253.15 K. • The capacity utilization increases from 86.98 % to 92.28 % at 253.15 K.