Inactive components and safety hazards are two critical challenges in realizing high-energy lithium-ion batteries. Metal foil current collectors with high density are typically an integrated part of lithium-ion batteries yet deliver no capacity. Meanwhile, high-energy batteries can entail increased fire safety issues. Here we report a composite current collector design that simultaneously minimizes the ‘dead weight’ within the cell and improves fire safety. An ultralight polyimide-based current collector (9 μm thick, specific mass 1.54 mg cm⁻²) is prepared by sandwiching a polyimide embedded with triphenyl phosphate flame retardant between two superthin Cu layers (~500 nm). Compared to lithium-ion batteries assembled with the thinnest commercial metal foil current collectors (~6 µm), batteries equipped with our composite current collectors can realize a 16–26% improvement in specific energy and rapidly self-extinguish fires under extreme conditions such as short circuits and thermal runaway.

非活性成分和安全隐患是实现高能锂离子电池的两个关键挑战。高密度金属箔集电器通常是锂离子电池不可或缺的一部分，但无法提供任何容量。同时，高能电池可能带来更多的消防安全问题。在这里，我们报告了一种复合式集电器设计，该设计可同时最大程度地减小电池内的“死重”并提高防火安全性。超轻聚酰亚胺基集电器（9μm厚，比重1.54 mg cm ^-2）是通过将嵌入磷酸三苯酯阻燃剂的聚酰亚胺夹在两个超薄铜层（〜500 nm）之间来制备的。与装配有最薄的商用金属箔集电器（〜6 µm）的锂离子电池相比，配备了我们的复合集电器的电池可以实现16％至26％的比能量提高，并在极端条件下（例如，短路和热失控。