The role of mechanically induced separator creep in lithium-ion battery capacity fade

► Mechanical response of batteries is dominated by electrochemically inactive materials. ► Stresses as low as 1 MPa cause viscoelastic creep and pore closure in the separator. ► Varying the magnitude of the stress simulates long-time viscoelastic creep. ► Power fade and capacity loss observed due to limited ion transport in the separator. ► Results can be generalized to other intercalation electrode energy storage systems.