Self-thermoregulating current collectors: built-in thermal protection for safe lithium-ion batteries†

Abstract

Significant heat is often generated within lithium-ion batteries during practical operation, particularly under fast-charging or extreme conditions. If not dissipated efficiently, this heat can induce catastrophic thermal runaway. In this study, we present a built-in thermal-responsive design based on a phase change composite current collector, which is constructed by impregnating paraffin, a phase change material, into a nanoporous copper foil, followed by sealing through electroplating. The resulting thermoregulating current collector (TCC), with a high heat storage capacity, serves as an alternative to conventional copper foils, providing self-actuated over-heating protection for temperature-sensitive anodes and their solid electrolyte interphases. When assembled with the TCC, 225-mAh LiFePO₄‖graphite pouch cells and 1-Ah LiNi_0.8Co_0.1Mn_0.1O₂‖graphite pouch cells demonstrate enhanced thermal safety due to latent heat storage. This work provides an effective route to built-in stimuli-responsive designs for safer lithium-ion batteries with high energy density.