Fabrication and Lithium Intercalation Properties of Graphite-Li₁₀P₃S₁₂Br Anode Composites

Abstract

A Li₁₀GeP₂S₁₂-type lithium-ion conductor Li₁₀P₃S₁₂Br was investigated as a potential solid electrolyte for composite anodes in all-solid-state lithium-ion batteries. Cyclic voltammetry measurements using an Au/Li₁₀P₃S₁₂Br/Li cell revealed that Li₁₀P₃S₁₂Br possesses a sufficiently wide electrochemical window, making it suitable for anode reactions at low potentials. Spherical graphite-Li₁₀P₃S₁₂Br composite anodes, fabricated via rotary mixing, exhibited lithium (de)intercalation activity, demonstrating the feasibility of Li₁₀P₃S₁₂Br as an electrolyte for all-solid-state battery anodes. Composite anodes with a higher proportion of Li₁₀P₃S₁₂Br relative to graphite exhibited improved cycle retention of charge-discharge capacities. A composite comprising graphite (d₅₀: 8 µm) and Li₁₀P₃S₁₂Br (d₅₀: 0.3 µm) in a 20:80 wt.% ratio achieved a discharge capacity of 365 mAh g⁻¹ at the 30th cycle. In contrast, the 50:50 wt.% composite exhibited a notable decrease in lithium intercalation capacity in the stage 2 (LiC₁₂) and stage 1 (LiC₆) regions. These results suggest that reducing the lithium diffusion distance within graphite particles is crucial for enhancing the intercalation properties of graphite/Li₁₀P₃S₁₂Br composite anodes.