Rationally-designed configuration of directly-coated Ni3S2/Ni electrode by RGO providing superior sodium storage

Designing nanocomposite materials is an effective approach for enhancing the performance of sodium-ion batteries (SIBs), and understanding the synergy among components is critically important for new, better materials design. Herein, a directly reduced graphene oxide (RGO) decorated anode electrode was designed and tested for SIBs, in which uniform RGO coating onto the Ni3S2/Ni electrode was realized using facile hydrothermal reactions. The results indicate that the RGO/Ni3S2/Ni electrode delivers a high reversible specific capacity of 448.6 mAh g(-1), high capacity retention of 96.5% after 100 cycles, and excellent rate capability of 263.1mAh g(-1) at 800mA g(-1). Compared with the Ni3S2/Ni electrode, the improved performance of the RGO/Ni3S2/Ni electrode benefits from RGO-promoted displacement reaction of Ni3S2 with sodium. DFT calculations reveal that the RGO layer can significantly improve the electron mobility of the RGO/Ni3S2 + Na structure, and the hybrid interaction between the extraneous p orbits of C and indigenous p and d orbits of Ni, as well as p orbits of S is the major reason for why RGO can improve the electrical transport properties. (C) 2018 Elsevier Ltd. All rights reserved.