Hydrogen Bonds Boost Lithium Salt Dissociation in Composite Solid‐State Electrolyte: Enhanced Cycling Life of Lithium Metal Batteries

Abstract Lithium metal batteries with composite solid‐state electrolytes are considered a promising approach to breaking through the energy limit of current lithium‐ion batteries. However, the low ionic conductivity of polymer electrolytes at room temperature and the stability of the electrode/electrolyte interface have become the major obstacles to the practical application of solid‐state lithium metal batteries. Here, thermoplastic polyurethane is crosslinked with poly(vinylidene fluoride) via hydrogen bonding interactions and combined with Li 1+x Al x Ge 2−x (PO 4 ) 3 (LAGP) to form a novel hybrid solid‐state electrolyte (denoted as TPLL). Experimental characterization and theoretical calculations have demonstrated that the rich 3D hydrogen bonding network in TPLL effectively increases the Li─O coordination number and promotes lithium salt dissociation, resulting in a high ionic conductivity of 0.182 mS cm −1 at 25 °C. Moreover, the abundant F groups effectively construct a stable electrode/electrolyte interface, enabling stable cycling of symmetric Li/Li cells for over 600 h at 0.1 mA cm −2 at room temperature. The Li/LiFePO 4 full cell assembled with TPLL‐CPE achieves excellent long‐term cycling stability with a decay rate of only 0.016% per cycle at room temperature. This strategy of hydrogen‐bonded crosslinking for salt dissociation opens up a new path for improving the solid‐state electrolytes.