A PVDF-Based Suspension Carbonate Electrolyte Drives Solvation-Sheath Regulation for Stable Lithium-Metal Batteries.

Abstract

Lithium-metal batteries (LMBs) are promising candidates for next-generation high-energy-density energy storage systems, but their practical application is limited by unstable Li-metal interfaces and poor compatibility of conventional carbonate electrolytes with high-voltage cathodes. Here, we report a poly(vinylidene fluoride) (PVDF)-based suspension carbonate electrolyte as an effective electrolyte-modification strategy, which improves the electrochemical stability of LMBs by enabling more uniform Li deposition and better oxidative stability. Molecular dynamics simulations combined with spectroscopic analyses reveal that fluorine-rich PVDF particle/electrolyte interfaces locally regulate Li+ coordination by weakening solvent-dominated solvation and enhancing anion participation around PVDF particles, thereby increasing contact ion pairs and aggregates. This promotes the formation of a gradient interphase with a fluorinated/organic-rich outer region and an inorganic inner region, while the intrinsically higher oxidation resistance of PVDF helps suppress parasitic reactions under high-voltage conditions. As a result, the suspension electrolyte delivers a Li+ transference number of 0.611, an oxidative stability window up to 4.7 V, and stable Li plating/stripping for over 2500 h in symmetric cells, while also improving the cycling stability and rate capability of Li||LiFePO4 and Li||NCM811 cells. This work provides a practical strategy for interfacial stabilization in carbonate electrolytes.