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

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 MoS 2 /SnS 2 -reduced graphene oxide (MoS 2 /SnS 2 -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 MoS 2 /SnS 2 -RGO calculated by GITT achieves 5.53 × 10 −7  cm 2  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 MoS 2 /SnS 2 -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, MoS 2 /SnS 2 -RGO possesses the highest reversible capacity among the reported anode materials . Furthermore, a SIC composed of optimized MoS 2 /SnS 2 -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 MoS 2 /SnS 2 -RGO anode and a Na 3 V 2 (PO 4 ) 3 /C cathode displays the reversible discharge capacity of 56 mA h g −1 at the high rates of 2 C.