In‐Situ Cross‐linked F‐ and P‐Containing Solid Polymer Electrolyte for Long‐Cycling and High‐Safety Lithium Metal Batteries with Various Cathode Materials

The practical application of lithium metal batteries (LMBs) has been hindered by limited cycle‐life and safety concerns. To solve these problems, we develop a novel fluorinated phosphate cross‐linker for gel polymer electrolyte in high‐voltage LMBs, achieving superior electrochemical performance and high safety simultaneously. The fluorinated phosphate cross‐linked gel polymer electrolyte (FP‐GPE) by in‐situ polymerization method not only demonstrates high oxidation stability but also exhibits excellent compatibility with lithium metal anode. LMBs utilizing FP‐GPE realize stable cycling even at a high cut‐off voltage of 4.6 V (vs Li/Li+) with various high‐voltage cathode materials. The LiNi0.6Co0.2Mn0.2O2|FP‐GPE|Li battery exhibits an ultralong cycle‐life of 1200 cycles with an impressive capacity retention of 80.1%. Furthermore, the FP‐GPE‐based batteries display excellent electrochemical performance even at practical conditions, such as high cathode mass loading (20.84 mg cm−2), ultrathin Li (20 μm), and a wide temperature range of −25 to 80 ℃. Moreover, the first reported solid‐state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse. Additionally, the industry‐level 18650 cylindrical LiMn2O4|FP‐GPE|Li4Ti5O12 cells demonstrate a remarkable cycle‐life of 1400 cycles. Therefore, the impressive electrochemical performance and high safety in practical batteries demonstrate a substantial potential of well‐designed FP‐GPE for large‐scale industrial applications.