High voltage stable cycling of all-solid-state lithium metal batteries enabled by top-down direct fluorinated poly (ethylene oxide)-based electrolytes

Poly (ethylene oxide) (PEO)-based solid-state polymer electrolytes (SPEs) show prospects in all-solid-state lithium metal batteries. However, they suffer from low ionic conductivity at room temperature and interfacial instability with high voltage cathodes for long-term cycling. In this work, top-down fluorinated PEOs (F-PEOs) for the all-solid-state electrolytes, which are scalable and cost-effective, are developed to improve the battery performance. We demonstrate, that by enhancing the disordering of the F-PEO matrix, the SPE achieves a maximum Li⁺ conductivity of 1.1 × 10^-4 S cm^-1 at 40 °C, which is 20 times higher than the baseline. By forming robust cathode/SPE and Li/SPE interfaces, the F-PEO-based SPEs demonstrate stable cycling in the LiFePO₄/Li and LiNi_0·8Mn_0·1Co_0·1O₂/Li (3-4.4 V, 500 cycles, capacity retention of 91.6%) based all-solid-state batteries at 40 °C. Furthermore, our work highlights the significance of "disordering engineering" for energy storage materials.