S/N co-doped graphene porous skeleton loaded with Ni-Co active material for lithium storage

Abstract

The flexible porous skeleton of S/N co-doped graphene aerogel (SNGA) can not only provide abundant ion transport channels but also improve the rate capability of graphene. Herein, taking the advantage of SNGA structure, NiCoO2 and NiCo2S4 were loaded onto the surface of SNGA (denoted as NiCoO2/SNGA-X and NiCo2S4/SNGA-X) via two-step hydrothermal and one-step hydrothermal method, respectively. The results show that NiCoO2 and NiCo2S4 particle agglomeration can be successfully mitigated since the Ni-Co binding process is influenced by the high specific surface area carbon source of SNGA. In addition, the NiCo2S4 prepared by one-step hydrothermal process plays the role of intercalation support during the formation of SNGA, which makes the porous structure of NiCo2S4/SNGA-X more compact and coherent. Benefiting from adequate active sites and porous structure, NiCoO2/SNGA-X and NiCo2S4/SNGA-X show high reversible capacity as anode materials for lithium energy storage. NiCoO2/SNGA-0.4 exhibits superior stability of 356.3 mA h g−1 at the current density of 1 A g−1 after 300 cycles, NiCo2S4/SNGA-0.3 exhibits excellent rate capability of 259.7 mA h g−1 at the current density of 5 A g−1. Lithium ion battery anode materials with high reversible specific capacity under high current density were successfully prepared. The research would provide a theoretical guidance for further application of SNGA skeletons.