Study on CxN and CxS with disordered carbon structure as the anode materials for secondary lithium batteries

CxN (x = 12.5 and 7.3) and CxS (x = 31.8 and 28.0) with disordered carbon structure was synthesized by chemical vapor deposition (CVD) from pyridine and thiophene, respectively, at 800 °C in the absence or presence of chlorine. Lithium was reversibly inserted into these materials. In addition, CxN and CxS had larger capacities than pyrolytic carbon synthesized by CVD from benzene at 800 °C. The capacities of CxN and CxS increased with increase in nitrogen or sulfur content. In particular, C7.3N had a first cycle discharge capacity of 507 mAh/g in the potential range of 0–3 V versus Li/Li+, which exceeds the theoretical capacity of graphite (372 mAh/g). C28.0S had a large first cycle discharge capacity of 551 mAh/g. The average interlayer spacing of C7.3N increased during charging and decreased during discharging like that of pyrolytic carbon. On the other hand, the average interlayer spacing of C28.0S hardly changed during charging and discharging.