A study of the effects of external pressure on the electrical performance of a lithium-ion pouch cell

The introduction of lithium-ion batteries for vehicle powertrain electrification has increased in recent years. They feature high energy density, high power density, long cycle life, and is also environmentally friendly compared with other types of batteries. A large number of Li-ion cells are usually required to meet the demand in capacity and power for automotive applications. Pouch cells have been favored by many manufacturers because of the high packaging efficiency and, therefore, a higher pack energy density. However, robust packaging is required for performance and safety criteria due to their low mechanical stability, which results in them being compressed in the module/pack. This paper describes research into the effects of external pressure on the electrical performance of lithium-ion pouch cells. The authors have adopted pulse power test, capacity test and electrical impedance spectroscopy test to characterize the effects and the test result indicates lithium-ion pouch cell´s performance changes under varying external pressures. Conclusions are drawn on how to make use of the results presented to influence and improve the design of automotive battery modules and packs to meet the challenges in the automotive industry.