WS2@NC Square Hexahedral Nanosheets with Na+-DME-Solvent Cointercalation Mechanism for Fast and Durable Sodium Ion Storage

Sodium-ion batteries (SIBs) face challenges in practical applications due to substantial volume expansion of anode materials and unstable solid–electrolyte interphases (SEIs), limiting their cycling life, rate performance, and reaction kinetics. Here, we report the successful synthesis of unique N-doped carbon-coated WS2 hexahedral nanoporous core–shell structures (WS2@NC) combined with a Na+-solvation strategy for high capacity and long-life sodium storage. Nanoporous architecture facilitates sufficient electrolyte infiltration and buffers volume expansion. The uniform N-doped carbon shell improves the conductivity, the stable inorganic-rich SEI improves the cycle stability, and the Na+-solvent cointercalation partially avoids the desolvation process and realizes the rapid reaction kinetics. Unique structural design and excellent compatibility with electrolytes give the WS2@NC electrode unprecedented long cycling life and rate capability in SIBs (207.7 mAh g–1 after 10,000 cycles at 20 A g–1 and 343 mAh g–1 at 50 A g–1). This work provides critical insights into performance enhancement mechanisms, offering a crucial theoretical basis for SIB applications.