Coupling the fast electron transportation of cobalt diselenide-based anode via cationic modulation for high rate Na+ storage

Abstract

The sodium-ion batteries (SIBs), as compelling candidate for partially replacing lithium-ion batteries (LIBs) in relevant application scenarios, is gaining increasing attention. The development of high-rate performance anode materials for sodium-ion batteries is exceptionally crucial. Here, a ZIF (zeolitic imidazolate framework) compound targeting bimetallic cations has applied through a pyrolysis-induced in-situ selenization strategy. This resulted in a nitrogen-doped porous carbon-encapsulated Fe-ion-modified CoSe2 material with a rhombic dodecahedron morphology (Fe-CoSe2@NC). The architecture not only effectively alleviates the bulk stress induced by the insertion/extraction of sodium ions, but also enhances the migration and transport of electrons/ions. Additionally, Fe doping enhances the material's conductivity and expedites reaction kinetics. Consequently, the Fe-CoSe2@NC exhibits outstanding rate performance and cycling stability (362.54 mAh g-1 after 1000 cycles at a current density of 10.0 A g-1) when utilized as an anode for SIBs in a coin-type half-cell. The Fe-CoSe2@NC also delivers a high initial coulombic efficiency (ICE) of 70.14%. This is substantiated by diffusion analysis and in-situ electrochemical impedance spectroscopy (EIS) characterization. The charging and discharging mechanisms of Fe-CoSe2@NC were verified through XRD and TEM characterizations during the electrochemical processes. When coupled with Na3V2(PO4)3 as the cathode material to form a full cell, the Fe-CoSe2@NC// Na3V2(PO4)3 battery system achieves a high energy density of 112.05 Wh kg-1. In this study, the successful construction of a transition metal selenide anode material for SIBs characterized by a stable structure and facilitation of rapid ion migration was demonstrated.