Transparent PVDF-based electrolyte enabled by lipophilic lithium magnesium silicate for solid-state lithium batteries

Solid-state batteries with solid polymer electrolytes are considered the most promising due to their high energy density and safety advantages. However, their development is hindered by the limitations of polymer electrolytes, such as low ionic conductivity, poor mechanical strength and inadequate fire resistance. This study presents a thin polyvinylidene fluoride-based composite solid electrolyte film (25 μm) incorporating two-dimensional modified lipophilic lithium magnesium silicate (LLS) as additives with good dispersibility. The incorporation of LLS promotes grain refinement in polyvinylidene fluoride (PVDF), enhances the densification of electrolyte films, increases the tensile strength to 10.42 MPa and the elongation to 251.58%, improves ion transport interface, and facilitates uniform deposition of lithium ions. Furthermore, LLS demonstrates strong adsorption ability, promoting the formation of solvated molecules, resulting in high ionic conductivity (2.07 × 10⁻⁴ S·cm⁻¹ at 30 °C) and a stable lithium/electrolyte interface. Symmetric Li//Li cells assembled with the thin composite electrolytes exhibit stable cycling for 2000 h at 0.1 mA·cm⁻² and 0.05 mAh·cm⁻². Additionally, the LiFePO₄//Li battery shows a capacity retention rate of 99.9% after 200 cycles at 0.5C and room temperature.

Graphical abstract