Chloride-Ion-Enriched Solid Electrolyte Interphase with Rapid Na⁺ Migration toward High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have emerged as potential alternatives to lithium-ion batteries (LIBs), particularly for large-scale applications. Alloy-type anode materials for sodium-ion batteries are esteemed as prospective candidate materials for sodium-ion anodes, owing to their elevated theoretical capacity, heightened utilization efficiency, and minimal production of insulating byproducts. However, the severe volume changes and sluggish ion diffusion kinetics can lead to irreversible particle fragmentation and reaggregation phenomena, ultimately resulting in electrode degradation. Additionally, repetitive volume changes can cause an unstable solid electrolyte interphase (SEI). This study presents the synthesis of chloride-ion-modulated bimetallic SnSb/C nanoparticle anode materials, highlighting the following advantages: (i) Designing a bimetallic SnSb alloy structure serves to buffer the structural stresses generated during sodium insertion/extraction processes, effectively mitigating particle fracture phenomena induced by electrode material expansion/contraction. (ii) Nanostructuring both alloy materials enables the full utilization of active materials and shortens diffusion pathways, thereby significantly enhancing the diffusion rate of sodium ions. (iii) Introducing a carbonaceous matrix serves to alleviate self-agglomeration phenomena of the material during charge/discharge cycles, enhancing the material's conductivity and structural stability. (iv) Utilizing chloride-ion interface modification to achieve a chloride-rich solid-electrolyte interphase (SEI) enhances battery performance.