The high-temperature adaptive interfacial chemistry engineering of sulfolane-based electrolytes enables long-cycle lithium-ion batteries under extreme temperatures (≥80 °C)

Abstract

With the growing demand for lithium-ion batteries (LIBs) capable of reliable operation under extreme high-temperature conditions (≥60 °C), conventional carbonate-based electrolytes face critical limitations due to thermal instability and interfacial degradation. In this study, we develop a sulfolane (SL)-based electrolyte incorporating fluorine-free vinylene carbonate (VC) as a functional additive to construct a high-temperature adaptive interfacial chemistry strategy. VC, featuring moderate coordination ability and interfacial passivation capability, enables controllable formation of thermally stable solid electrolyte interphases (SEIs). Systematic analysis reveals that increasing temperature induces a transition from solvent-separated ion pairs (SSIPs) to contact ion pairs (CIPs) and aggregated ion clusters (AGGs), which promotes the formation of a composite SEI comprising LiF-rich inorganic phases and poly(VC) networks. The interwoven SEI exhibits excellent mechanical integrity, thermal robustness, and facilitates efficient Li⁺ transport. Electrochemical evaluations demonstrate that the SL-based electrolyte enables graphite half-cells to retain 95.89 % of capacity after 200 cycles at 60 °C, and pouch cells (NCM523||graphite) maintain 89.55 % of capacity after 1000 cycles at 60 °C, outperforming conventional systems. These results highlight the potential of SL-based electrolytes for safe and long-lasting high-temperature LIB applications.