Interfacial engineering of metal oxide/graphene nanoscrolls with remarkable performance for lithium ion batteries

The strong interfacial interaction between graphene nanosheets (GNS) and metal oxides (MO) intensively enhances Li+ diffusion, achieving superior rate capability and excellent cycle stability as such interaction strongly restricts the expansion of MO near the interface during lithiation. However, how to design strong interface between GNS and MO is a challenge. Herein, strong interface was achieved by adding sodium citrate (SC) during the dispersion and mixing process of GO and MO (i.e., Fe3O4, Co3O4 and NiO). The use of SC enables better dispersion of MO particles and allows every MO particle to be attached on the GNS. The discharge capacity of Fe3O4@GNS(SC) was 1882 mA h g(-1) in the second cycle at 0.1C which is higher than Fe3O4@GNS (1120 mA h g(-1)), and maintained at 1610 mA h g(-1) after 100 cycles much better than that of Fe3O4@GNS (810 mA h g(-1)). The Fe3O4@GNS(SC) composite material also delivered excellent rate performance of 1035 mA h g(-1) at 1C, in contrast to Fe3O4@GNS(680 mA h g(-1)). In the case of NiO and Co3O4, the corresponding composites displayed the same tendency as Fe3O4@GNS(SC). These results imply that SC with an oxygen functional group and short carbon chain can ensure a large contact area between MO and GNS and short diffusion path for lithium ions in the active material. This work may pave a way for obtaining GNS-based materials for efficient electrochemical energy storage.