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

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 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 °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.