Heatable Polymer Current Collectors for Cold‐Climate Battery Operation

Abstract Low‐temperature operation remains a big challenge for lithium‐ion batteries (LIBs), primarily due to hinders ion transport and lithium dendrite formation. Herein, a polymer‐based composite current collector (CC) with an embedded polyimide/carbon nanotubes (PI/CNTs) Joule heating layer is presented that enables rapid, low‐current internal heating to enhance battery performance in cold environments. The obtained heatable H─Al CCs achieve uniform surface temperatures up to 77.5 °C under 97 mA at 25 V, offering a heating rate three times faster than conventional external methods while reducing the mass by 29.9% compared with commercial Al CCs. When integrated into pouch cells, this design leads to a 3.35‐fold increase in discharge capacity at 0 °C (2.78 Ah vs 0.83 Ah), with 97.9% capacity retention after prolonged cycling at 0.5 C. Mechanistically, localized heating accelerates Li⁺ transport and modifies nucleation behavior, effectively suppressing dendrite growth and promoting dense, uniform lithium deposition even at subzero temperatures. This scalable, lightweight heating strategy provides a robust solution for improving the safety and electrochemical performance of LIBs in cold climates without altering the core cell architecture.