Failure mechanism and predictive model of lithium-ion batteries under extremely high transient impact

•The voltage of lithium-ion batteries under high impact is measured, with a sharp drop and slow rise.•The partial short circuit of the separator and the relaxation effect contribute to the impact failure.•MI-PNGV model is proposed to simulate the failures under different extreme mechanical conditions.•The design guideline is proposed to avoid the mechanic impact failure of lithium-ion batteries.