Bimetallic MOF-Derived CoS₂/CuCo₂S₄ Particles Anchoring on Nitrogen-Doped Carbon Framework as Anodes for Sodium-Ion Batteries

Cobalt disulfide (CoS₂) has attracted much attention as anodes of sodium-ion batteries (SIBs) due to its high theoretical capacity. Nevertheless, the serious volume variation and polysulfide dissolution issues during cycling usually lead to poor electrochemical performance, greatly limiting its application. Here, by employing a CuCo-based metal organic framework (MOF) and bacterial cellulose (BC) as precursor and template, we have fabricated heterostructured CoS₂/CuCo₂S₄ particles anchoring on an N-doped carbon framework (denoted as CuCo-S/NC) through ion adsorption and exchange reaction with a subsequent thermal annealing process. The generation of a CoS₂/CuCo₂S₄ heterostructure which can boost the charge transfer rate in the hybrid composite has been investigated, while the introduction of an N-doped carbon framework derived from the BC could not only enhance the electrical conductivity but also improve the structural integrity by mitigating the mechanical stress and inhibiting the aggregation of active materials. Benefitting from the designed composition and structure, the optimal CuCo-S/NC electrode exhibits a high capacity of 889 mAh g⁻¹ at 0.2 A g⁻¹ and an outstanding rate capability of 394 mAh g⁻¹ at 10 A g⁻¹. The results achieved in this work indicate the great potential of this bimetallic MOF-derived template method for the rational design and fabrication of novel hybrid composite anodes for high-performance SIBs.