Structure analyses using X-ray photoelectron spectroscopy and X-ray absorption near edge structure for amorphous MS3 (M: Ti, Mo) electrodes in all-solid-state lithium batteries

• Electronic structure changes of sulfurs in amorphous TiS3 and MoS3 are examined.
• Reversible sulfur redox of S2− and S22− in a-TiS3 mainly occurs during cycling.
• Irreversible sulfur structure change in a-MoS3 affects the 1st cell reversibility.

Electronic structure changes of sulfurs in amorphous TiS3 and MoS3 for positive electrodes of all-solid-state lithium batteries are examined by X-ray photoelectron spectroscopy (XPS) and the X-ray absorption near edge structure (XANES). The all-solid-state cell with amorphous TiS3 electrode shows the reversible capacity of about 510 mAh g−1 for 10 cycles with sulfur-redox in amorphous TiS3 during charge-discharge process. On the other hand, the cell with amorphous MoS3 shows the 1st reversible capacity of about 720 mAh g−1. The obtained capacity is based on the redox of both sulfur and molybdenum in amorphous MoS3. The irreversible capacity of about 50 mAh g−1 is observed at the 1st cycle, which is attributed to the irreversible electronic structure change of sulfur during the 1st cycle. The electronic structure of sulfur in amorphous MoS3 after the 10th charge is similar to that after the 1st charge. Therefore, the all-solid-state cell with amorphous MoS3 electrode shows relatively good cyclability after the 1st cycle.