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

A fluorinated phosphate cross-linked gel polymer electrolyte (FP-GPE) has been designed and fabricated for high-voltage lithium metal batteries (LMBs). The FP-GPE-based batteries display excellent electrochemical performance and high safety simultaneously even at practical conditions. Moreover, the first reported solid-state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse.

Abstract

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 LiNi_0.6Co_0.2Mn_0.2O₂|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 °C. 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.

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