Talc Nanosheet Ionogel Electrolytes with High Lithium-Ion Conductivity for Solid-State Lithium Metal Batteries

Ionogels are attractive solid-state electrolytes for lithium (Li) metal batteries due to their nonflammability, favorable electrochemical properties, and broad processing compatibility. However, they typically present limited Li-ion conductivity resulting from low Li-ion transference numbers, constraining their battery performance. Here, ionogel electrolytes with high Li-ion conductivity are introduced based on liquid-phase-exfoliated talc nanosheets and an imidazolium ionic liquid. While serving as a solid matrix to confine the ionic liquid and solidify the ionogel electrolytes, the talc nanosheets reduce the formation of Li-ion complexes with the ionic liquid anions, thus improving Li-ion mobility. These effects are promoted by the large surface area of the talc nanosheets, significantly enhancing the Li-ion transference number of the ionogel electrolytes. The resulting talc nanosheet ionogel electrolytes show high Li-ion conductivity up to 0.9 mS cm^-1 at room temperature, enabling the fabrication of solid-state LiFePO₄|Li batteries with superlative rate performance and excellent cycling stability.