PVP-Assisted Synthesis of N-Doped Spatial Confinement Carbon-Coated CoS 2 Anode for Sodium-Ion Batteries with Long Cycle Life

Abstract

The limited availability of lithium resources significantly constrains the sustainable development and large-scale application of lithium-ion batteries.Encouragingly, the abundance of sodium resources and their chemical similarity to lithium render sodium-ion batteries highly promising for large-scale energy storage applications. In this study, a nitrogen-doped carbon-encapsulated CoS 2 nano-anode material with core-shell interstitial voids (denoted as N-CoS 2 @C-PVP) was successfully fabricated via a rationally designed preparation process. By introducing PVP, which adsorbs onto the particle surface to form a protective layer, the spatial steric hindrance effect effectively inhibits particle agglomeration, thereby facilitating the synthesis of nanoparticles and the realization of nitrogen doping. Benefiting from the PVP protective layer, a carbon coating with a cavity structure was constructed during calcination and carbonization. This structural architecture effectively accommodates the repeated volume expansion and contraction of CoS 2 during sodiation/desodiation processes, thus enhancing the cycling stability of the material.The N-CoS 2 @C-PVP anode retains a discharge specific capacity of 377.55 mAh g -1 after 3000 cycles at 1 A g -1 , with a corresponding capacity retention of 62.61%, which is significantly superior to that of the PVP-free N-CoS 2 @C counterpart. Additionally, the synergistic effect between nano-sized CoS 2 particles and nitrogen doping enhances the specific capacity and rate capability of the material.