Enhancing Rapid Li⁺/Na⁺ Storage Performance via Interface Engineering of Reduced Graphene Oxide-Wrapped Bimetallic Sulfide Nanocages

Transition-metal sulfide is considered to be an admirable transformational electrode material due to low cost, large specific capacity, and good reversibility in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Herein, the reduced graphene oxide-wrapped open bimetallic sulfide (NiS₂-Co₃S₄@rGO) nanocage, derived from nickel-cobalt Prussian blue, was obtained by two-step calcination. There are luxuriant pore structures in the nanocage composite with a specific surface area of 85.28 m² g^-1, which provides plentiful paths for rapid transmission of Li⁺/Na⁺ and alleviates the volume stress caused by insertion and extraction of alkali metal ions. The excellent interface combination of bimetallic sulfide wrapped in reduced graphene oxide improves the conductivity and overall performance of the battery. Thanks to the special interface engineering, the open NiS₂-Co₃S₄@rGO nanocage composite displays rapid lithium storage properties with an average diffusion coefficient of 8.5 × 10^-13 cm² s^-1. Moreover, after 300 cycles, the reversible capacity of the composite is 1113.2 mAh g^-1 at 1 A g^-1. In SIBs, the capacity of the open NiS₂-Co₃S₄@rGO composite is 487.9 mAh g^-1 when the current density is 5 A g^-1. These preeminent performances demonstrate the enormous development prospects of bimetallic sulfide nanocage as anode material in LIBs and SIBs.