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

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, NiCoO 2 and NiCo 2 S 4 were loaded onto the surface of SNGA (denoted as NiCoO 2 /SNGA-X and NiCo 2 S 4 /SNGA-X) via two-step hydrothermal and one-step hydrothermal method, respectively. The results show that NiCoO 2 and NiCo 2 S 4 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 NiCo 2 S 4 prepared by one-step hydrothermal process plays the role of intercalation support during the formation of SNGA, which makes the porous structure of NiCo 2 S 4 /SNGA-X more compact and coherent. Benefiting from adequate active sites and porous structure, NiCoO 2 /SNGA-X and NiCo 2 S 4 /SNGA-X show high reversible capacity as anode materials for lithium energy storage. NiCoO 2 /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, NiCo 2 S 4 /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. [Display omitted] • The surface-distributed N atoms with the metal ions and the presence of sulfur-metal bonds improve the stability of material. • NiCo 2 S 4 /SNGA-0.3 shows excellent rate capability (259.7 mA h g−1 at 5 A g−1). • NiCoO 2 /SNGA-0.4 shows superior stability (356.3 mA h g−1 at 1 A g−1 after 300 cycles). • The rich pore structure helps to slow down the accumulation of graphene flakes and to reduce the volume expansion. [ABSTRACT FROM AUTHOR]