Solvent-assisted ligand exchange induces the epitaxial growth of VSe2 on the surface of a 3D nitrogen-doped carbon network for ultra-long-life lithium/sodium-ion batteries

Abstract

Metal selenides (MSes) possess high capacity and conductivity; however, the problems of volume expansion and polyselenide shuttling still need to be solved. Herein, a nitrogen-doped carbon (NC)-supported VSe₂ composite (VSe₂/NC) was synthesized via a solvent-assisted ligand exchange method. The findings of this study demonstrate that NC effectively inhibits VSe₂ structural expansion and polyselenide dissolution. The optimized VSe₂/NC composite displays exceptional cycling durability in lithium/sodium-ion batteries (LIBs/SIBs): 192 mAh g⁻¹ in LIBs (10 A g⁻¹, 4500 cycles) and 314.4 mAh g⁻¹ in SIBs (2 A g⁻¹, 500 cycles). With lithium cobalt oxide (LiCoO₂) as the positive electrode, the VSe₂/NC‖LiCoO₂ full cell delivers an energy density of 127.5 Wh kg⁻¹ and a power density of 85 W kg⁻¹. It exhibits a capacity retention of 83.43% after 300 cycles at 0.2 C and illuminates 202 LEDs for 5 minutes. Experimental and density functional theory (DFT) calculations all reveal that the excellent battery performance arises from NC incorporation, which induces porous structures and structural defects, boosting alkali-ion migration rates and storage site density. This work establishes a new design strategy for high-rate battery anode materials.