Charge–discharge properties of tin dioxide for sodium-ion battery

• The electrochemical reaction of SnO2 as an anode for Na-ion batteries was studied.
• The SnO2 electrode delivered the initial discharge capacity of 747 mAh/g.
• Alarge irreversible capacity (597 mAh/g)was observedin the first cycle.
• The in-plain crack in the electrode caused the incompletereduction of SnO2.

Tin dioxide was investigated as an anode material for sodium-ion batteries. The Na/SnO2 cell delivered a first discharge capacity of 747 mAh/g, but the first charge capacity was 150 mAh/g. The irreversible capacity in the first cycle was examined through characterization by X-ray diffraction and scanning electron microscopy. X-ray diffraction analysis revealed that the SnO2 active material was not reduced fully to metallic Sn. Furrows and wrinkles were formed on the electrode surface owing to the volumetric expansion upon first discharge, which led to a deterioration of the electrode structure and a loss of electrical contact between the active materials. The analysis is summarized in the schematic drawing.

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