Solvent Chain‐Length Engineering Enables All‐Climate Sodium‐Ion Batteries
Zongbin Luo, Linyu Hu, Chunlong Dai, Guoliang Ma, Yong Ye, Kui Xu, Zifeng Lin
Abstract
Abstract Achieving high‐rate capability, long‐term cycling stability, high‐voltage tolerance, and wide‐temperature adaptability in sodium‐ion batteries (SIBs) remains a challenge due to intrinsic solvent trade‐offs. Here, we propose a molecular‐scale electrolyte design strategy addressing this multi‐objective optimization through solvent chain‐length engineering. By coupling short‐chain ethers (low‐temperature kinetics) and long‐chain glycol ethers (high‐voltage/thermal stability) with 1,3‐dioxolane (DOL) and fluoroethylene carbonate (FEC), we construct a hybrid‐solvent electrolyte that redefines Na⁺ solvation chemistry. Systematic solvent–solvent interaction modulation weakens Na⁺‐solvent binding to accelerate ion transport, while FEC‐induced anion‐rich coordination shells enhance interfacial stability. The hybrid electrolyte enables Na 3 V 2 (PO 4 ) 3 ||Na cells to deliver an 82.75 mAh g −1 discharge capacity after 9500 cycles at 10 C, sustain 600‐day operation at 1 C, and function across −40 to 60 °C. Symmetric Na||Na cells demonstrate stable cycling for over one year. Moreover, the electrolyte exhibits good compatibility with various commercial cathode materials within a wide voltage window of 2.0–4.5 V and demonstrates excellent wide‐temperature adaptability in full‐cell systems. This work demonstrates solvent chain‐length‐driven solvation engineering as a viable strategy to concurrently address kinetic, thermodynamic, and interfacial challenges, offering a practical pathway toward all‐climate SIBs with balanced multi‐performance metrics.