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.