High-capacity and fast Na-ion diffusion rate three-dimensional MoS2/SnS2-RGO anode for advanced sodium-ion batteries and sodium-ion capacitors

Abstract

Sodium-ion batteries (SIBs) and Sodium-ion capacitors (SICs) have great promise for large-scale energy storage. However, the mismatch of electrode kinetics and charge-storage capacity between anode and cathode materials remains a challenge. Here three-dimensional self-assembled MoS2/SnS2-reduced graphene oxide (MoS2/SnS2-RGO) anode material with fast Na-ion diffusion rate and pseudocapacitive charge storage has been successfully prepared via a facile hydrothermal method. With this particular structure, the Na-ion diffusion coefficient of MoS2/SnS2-RGO calculated by GITT achieves 5.53 × 10−7 cm2 s−1 during the desodiation process, which effectively improves the reaction kinetics for anode material. When tested against metal sodium in the potential window of 0.01–3.00 V, the optimized MoS2/SnS2-RGO delivers an excellent reversible capacity of 818.9 mA h g−1 at a specific current of 100 mA g−1 after 100 cycles and a superior rate capability of 555.4 mA h g−1 at 2000 mA g−1 over 500 cycles. So far, MoS2/SnS2-RGO possesses the highest reversible capacity among the reported anode materials. Furthermore, a SIC composed of optimized MoS2/SnS2-RGO anode and a CC cathode reaches a high specific energy of 113.9 W h kg−1 at specific power of 561.25 W kg−1. Similarly, a SIB consisted of the MoS2/SnS2-RGO anode and a Na3V2(PO4)3/C cathode displays the reversible discharge capacity of 56 mA h g−1 at the high rates of 2 C.