Bimetallic Organic Framework-Derived MnSe/CoSe2/C Heterostructure as High-Performance Anode Material for Sodium-Ion Batteries

Abstract Metal selenides, which combine high theoretical capacity with excellent electrical conductivity, represent promising anode materials for sodium-ion batteries. Nevertheless, the significant volume changes during cycling and the poor ion diffusion kinetics of metal selenides result in inferior cycling stability and rate capability, constraining practical applications. In this study, a porous MnSe/CoSe2/C hybrid was fabricated by the selenization of a MnCo-MOF-74 precursor. The built-in electric field within the MnSe/CoSe2/C heterostructure facilitates charge migration, which significantly boosts Na+ diffusion kinetics. Moreover, the potential difference between MnSe and CoSe2 promotes the formation of buffer phases, which, together with the MnCo-MOF-74-derived carbon coating, markedly mitigate the volumetric expansion of the active materials, thus boosting cycling stability. In terms of electrochemical performance, MnSe/CoSe2/C∥Na cells deliver a discharge capacity of 285.4 mAh/g with a 71.52% capacity retention rate after 3000 cycles at 2 A/g. This synthesis strategy provides an effective pathway for optimizing ion diffusion kinetics and the cycling stability of metal selenides, while expanding the application boundaries of MOF materials in energy storage.