Synthesis and Electrochemical Properties of Oxygen-deficient Crystalline Lithium Silicon Oxide for the Anode of All-Solid-state Lithium-Ion Batteries

Oxygen-deficient crystalline LiSiO _2 − x materials for the anode of all-solid-state lithium batteries (ASLBs) were prepared using a sol-gel and reduction process. The resulting powder had a composition of Li _1.2 Si ₁ O _1.86 , with a particle size of approximately 20 µm and good crystallinity. The change in oxygen content on the particle surface was examined by X-ray photoelectron spectroscopy, indicating that oxygen deficiency was optimized when heat-treated at 700°C after silicon addition. The powder was then mixed with graphite (Gr), Li _6.25 Al _0.25 La ₃ Zr ₂ O ₁₂ (LLZO), polyethylene oxide (PEO), and Super-P in specific ratios to form a composite anode. To investigate the effect of silicon oxide on the anode, the LiSiO _2 − x :graphite ratio was varied across three compositions (10:0, 5:5, and 2:8). ASLBs were fabricated using a half-cell configuration with 2032-coin cells, consisting of a working electrode made of LiSiO _2 − x composite anode, a solid electrolyte composed of LLZO-PEO composite film, and a lithium metal counter electrode. No liquid electrolyte was used, and LiClO ₄ salt was incorporated into both the anode and electrolyte. Electrochemical testing revealed that the cell with a Si:Gr ratio of 2:8 exhibited an initial capacity of 360 mAh g ^− 1 , confirming reduced irreversible capacity loss during cycling.