Graphene oxide assisted template-free synthesis of nanoscale splode-like NiCoO hollow microsphere with superior lithium storage properties.

A facile template-free Ostwald ripening method is developed for the preparation of the reduced graphene oxide supported splode-like NiCoO hollow microsphere (SNHM/rGO). The graphene oxide used in the reaction mixture is found to play a crucial role in the formation of the SNHM/rGO. It promotes the formation of the NiCo-glycerol microspheres suitable for the Ostwald ripening to form the reduced graphene oxide supported hollow NiCo-glycerol microspheres, which is important for the subsequent calcination to form the SNHM/rGO. The obtained SNHM/rGO shows a great promise as the anode for lithium-ion batteries and can deliver a stable reversible capacity of 1048.1 mA h g at the current density of 100 mA g. The performance of the SNHM/rGO is much higher than that of most NiCoO-based materials reported previously, strongly suggesting that the SNHM/rGO could be used as the anode for practical applications. This is well supported by the higher performance of the LiCoO//SNHM-rGO full cell. The excellent electrochemical performance can be attributed to the specific structure of the SNHM/rGO, which comprises the splode-like hollow NiCoO microspheres with the reduced graphene oxide integrated.