Pyrolytic carbon from graphite oxide as a negative electrode of sodium-ion battery

•Pyrolytic carbons with various interlayer spacing were obtained from graphite oxide.•The reversible capacity reached 252 mAh g−1.•Sodium ions were inserted between the carbon layers.

Carbons with various interlayer spacings of 0.422–0.334 nm were prepared from the pyrolysis of graphite oxide at various temperatures. Raman measurement indicated that these carbons contain many defects even when the interlayer spacing was almost comparable to that of graphite. The charge and discharge potentials monotonically changed when they were used for the negative electrode of sodium-ion battery, which was rather similar to that observed for soft carbons. The maximum reversible capacity reached 252 mAh g−1 for the carbon prepared at 300 °C and it showed relatively good cycling stability. The X-ray diffraction pattern of it after charged to 0 V indicated that sodium ions are inserted between the carbon layers, forming a stage 1 intercalation compound. The capacity slightly decreased as the increase in the temperature for pyrolysis and more steeply decreased above 900 °C, however, the carbon obtained at 1000 °C still delivered a capacity of 95 mAh g−1.