Modeling, design, and simulation of pouch battery packs for stratospheric airships considering temperature distribution and air pressure effects

The performance of pouch battery packs is significantly affected by the low temperature and low pressure (LTLP, −65 °C, 5 kPa) conditions encountered by stratospheric airships, leading to considerable performance variations among individual cells. To address this problem, a battery pack model based on the equivalent circuit model (ECM) for single cells is developed, incorporating additional resistance, thermal distribution, and air pressure effects. Firstly, the thermal model of the battery pack was established by COMSOL, and the heat production coefficient of the pack was obtained, which was about 3.5 %. Combined with the additional heating device, the simulation indicated the thermal distribution of the pack under the LTLP conditions is in a multi-peak state and can be stably maintained in a suitable temperature range. Secondly, it is found that the cell will produce about 19.1 % expansion displacement which resulting in performance degradation at 5 kPa. The preload force model of the battery pack was established. And when the preload force of 50 kPa is designed for 48-series pack, the expansion of the pack can be effectively suppressed, so that the battery pack can maintain the rated capacity level at 5 kPa. Finally, the battery pack model is constructed to suitable for the stratospheric airship, and the accuracy of the proposed model is verified by tests and simulations at 2 conditions: normal temperature and normal pressure (NTNP, 25 °C, 1 atm) and LTLP. • The thermal distribution for the battery packs were obtained through simulation of the thermal model by COMSOL. • The preload force model is constructed to solve the expansion of the pouch battery affected by low air pressure. • Considering various influencing factors of stratospheric airship on battery system, a battery pack model is constructed. • The effects of air pressure and temperature on the design of battery systems for stratospheric airships is analyzed.