Dynamic failure analysis of lithium-ion battery under high-velocity impact using the FE-SPH based simulation

Lithium-ion batteries are inevitably subjected to mechanical abuses of high-velocity impact on the battlefield, challenging the safety of electrified military equipment. It is vital to understand the failure mechanisms of batteries under high-velocity impacts, nevertheless limited by the lack of effective numerical and experimental methods. For this purpose, a FE-SPH based numerical model considering equivalent homogeneous electrodes is established to investigate the dynamic failure behaviors of LIBs under high-velocity impact. Compared to FEM method using element deletion, the FE-SPH method addresses the problem of numerical sudden drop in resistance force during dynamic indentations. We precisely simulate damage morphologies of impacted batteries compared to previous ballistic tests, and the debris cloud of crushed battery components is well reproduced. The effect of stress wave in the dynamic failure of electrodes and separators in LIBs is revealed during the penetration stage, which affects the fragment distribution in the structural response stage of impacted batteries. Furthermore, we systematically investigate the effects of battery thickness, impact velocity and penetrator shape on the damaged morphologies and structural debris cloud of impacted LIBs. The mechanical failure sequence of battery components is then compared between the low-velocity and high-velocity impact. It's deduced that cathode and anode layers fail before the rupture of separators in LIBs under the high-velocity impact, underlying that the heat generation is not mainly attributed to instantaneous electrochemical short circuits caused by the rupture of the separator. This study provides new insights for understanding the failure mechanism and protection design for batteries.