In Situ High‐performance Gel Polymer Electrolyte with Dual‐reactive Cross‐linking for Lithium Metal Batteries

Lithium metal batteries have been considered as one of the most promising next‐generation power‐support devices due to their high specific energy and output voltage. However, the uncontrollable side‐reaction and lithium dendrite growth lead to the limited serving life and hinder the practical application of lithium metal batteries. Here, a tri‐monomer copolymerized gel polymer electrolyte (TGPE) with a cross‐linked reticulation structure was prepared by introducing a cross‐linker (polyurethane group) into the acrylate‐based in situ polymerization system. The soft segment of polyurethane in TGPE enables the far migration of lithium ions, and the ‐NH forms hydrogen bonds in the hard segment to build a stable cross‐linked framework. This system hinders anion migration and leads to a high Li + migration number ( = 0.65), which achieves uniform lithium deposition and effectively inhibits lithium dendrite growth. As a result, the assembled symmetric cell shows robust reversibility over 5500 h at a current density of 1 mA cm −2 . The LFP¦¦TGPE¦¦Li cell has a capacity retention of 89.8% after cycling 800 times at a rate of 1C. In summary, in situ polymerization of TGPE electrolytes is expected to be a candidate material for high‐energy‐density lithium metal batteries.