How does room temperature cycling ageing affect lithium-ion battery behaviors under extreme indentation?

Safety of lithium-ion battery (LIB) cells throughout the whole lifecycle has drawn enormous research interest. Understanding how cycling ageing affects the mechanical-electrical-thermal responses of LIB cells under mechanical abuse is meaningful for more considerate safety design. In the present study, impact of room temperature ageing on morphology of lithium-ion pouch cell was experimentally explored at first, which clearly identified the deposition phenomenon on electrodes induced by electrolyte consumption. Spherical indentation along out-of-plane direction was carried out on both pristine and aged cells, in which the mechanical-electrical-thermal responses were all monitored. Test results indicate that the mechanical response of the aged cells is quite distinct from the pristine ones, characterized by a rightward shift of the force-displacement curve. Electrical and thermal responses of the aged cells were comparatively less severe. It is inferred that those deposits generated during the ageing process postpone the failure of cells. The short circuit of aged cells behaves relatively tenderly as short contact is alleviated by deposits on the surface of electrodes. By combining the present results with previous researches, correlation between the ageing mechanism and the mechanical abuse failure was sorted for different cells subjected to different ageing processes. It is recognized that changes in mechanical, electrical, and thermal responses of aged cells are highly dependent on both ageing condition and battery configuration.