Wan, MintaoMintaoWanFei, HuifangHuifangFeiLiu, HaowenHaowenLiuNAE-LIH WUPasserini, StefanoStefanoPasseriniBresser, DominicDominicBresser2026-01-082026-01-082026-03https://www.scopus.com/record/display.uri?eid=2-s2.0-105023143515&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/735150Energy density and safety are two crucial parameters when evaluating lithium-metal batteries (LMBs). Herein, we present an ultralight polymer-based current collector, incorporating flame-retardant materials, designed specifically for thin lithium-metal anodes. Compared to the traditional copper current collector (8.96 mg cm−2, 10 μm thick), the polymer-based current collector (12 μm thick) has a significantly lower areal density of 1.41 mg cm−2, i.e., only one-sixth of the copper collector, thus enabling substantially higher energy densities. Accordingly, when employed in Li||NMC622 full-cells, the polymer-based current collector enables a specific energy of 449 Wh kg−1, representing a notable improvement of about 14.5% compared to cells employing a classic copper current collector. The inclusion of Al(OH)3 as a flame retardant into the current collector suppresses flammability and, thereby, significantly improves the safety of the resulting LMBs.BatteryCurrent collectorFlame retardantLithium-metal anodePolymerjournal article10.1016/j.jechem.2025.10.052