Electrolyte Chemistry Toward Sulfur‐Rich Interphase for Wide‐Temperature Sodium‐Ion Batteries

Abstract Achieving wide‐temperature operation is a crucial objective for the practical deployment of sodium‐ion batteries (SIBs). However, the development of suitable electrolytes is hindered by significant challenges, including compromised ionic dynamics at low temperatures and interphase instability at high temperatures. Herein, this study proposes a novel interphase enhancement mechanism utilizing a sulfur‐rich strategy, grounded in rational solvent selection. This approach enriches the electrolyte with sulfur‐containing species that exhibit high Na + affinity and efficient ionic migration at both the cathode and anode sides. Consequently, this strategy significantly enhances interfacial charge transfer and interphase integrity, confirmed by theoretical calculations and electrochemical measurements. The designed electrolyte demonstrates robust performance in half‐cells based on Na 3 V 2 (PO 4 ) 3 (NVP) across a wide temperature range from −25 to 60 °C. Furthermore, the full‐cell, featuring an NVP cathode paired with a hard carbon anode, exhibits exceptional stability. Specifically, the full cell achieves reversible capacities of 56.1 mAh g −1 after 100 cycles at −25 °C and 74.9 mAh g −1 after 100 cycles at 60 °C, with impressive capacity retentions of 87.7% and 88.2%, respectively. Importantly, the study introduces an advanced interphase optimization strategy that enables the operation of SIBs across wide temperatures, providing practical solutions for future developments in the field.