Large-scale current collectors for regulating heat transfer and enhancing battery safety

Thermal runaway, a major battery safety issue, is triggered when the local temperature exceeds a threshold value resulting from slower heat dissipation relative to heat generation inside the cell. However, improving internal heat transfer is challenged by the low thermal conductivity of metal current collectors (CCs) and challenges in manufacturing nonmetal CC foils at large scales. Here we report a rapid temperature-responsive nonmetallic CC that can substitute benchmark Al and Cu foils to enhance battery safety. The nonmetallic CC was fabricated through a continuous thermal pressing process to afford a highly oriented Gr foil on a hundred-meter scale. This Gr foil demonstrates a high thermal conductivity of 1,400.8 W m−1 K−1, about one order of magnitude higher than those of Al and Cu foils. Importantly, LiNi0.8Co0.1Mn0.1O2||graphite cells integrated with these temperature-responsive foils show faster heat dissipation, eliminating the local heat concentration and circumventing the fast exothermic aluminothermic and hydrogen-evolution reactions, which are critical factors causing the thermal failure propagation of lithium-ion battery packs. Understanding and preventing thermal runaway is critical to ensuring the safe and reliable operation of batteries. Here the authors demonstrate the large-scale production of a highly conductive graphene-based foil current collector to mitigate thermal runaway in high-capacity batteries.