Fabrication and Lithium Intercalation Properties of Graphite-Li<sub>10</sub>P<sub>3</sub>S<sub>12</sub>Br Anode Composites

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.