Key Findings
Researchers from UNIST and KAIST have developed an electrolyte formulation that triples the cycle life of lithium-metal batteries compared to conventional electrolytes tested under identical conditions. The formulation consists of two inexpensive, commodity solvents—ethylene carbonate (EC) and sulfolane (SL)—mixed at a 3-to-7 weight ratio, combined with a lithium salt and a small quantity of an SEI-stabilizing additive. This result was reported in ACS Nano on August 11, 2026.
Technical Details
The performance gain is attributed to a mechanism called “cooperative solvation.” While EC and SL individually bind too strongly to lithium ions to be suitable for lithium-metal anodes, mixing them creates strong intermolecular hydrogen bonds between EC’s hydrogen atoms and SL’s oxygen atoms. This interaction pulls the solvent molecules toward each other rather than toward the lithium ion.
- Desolvation: The hydrogen bonding reduces the total binding energy, making it easier for lithium ions to shed their solvent shell (desolvation) before depositing on the anode.
- Solvation Sheath: Computational modeling verified that both solvents appear simultaneously in the first solvation sheath in a new configuration, sharing the coordination of the lithium ion.
Background & Context
Lithium-metal batteries theoretically offer significantly higher energy density per kilogram than graphite-anode batteries, potentially doubling or increasing range up to ten times. However, lithium metal is highly reactive, leading to the continuous growth and cracking of the solid electrolyte interphase (SEI) and the formation of needle-like dendrites. To combat this, engineers previously relied on expensive fluorinated solvents or very high salt concentrations to weaken the solvent’s grip on lithium ions.
Significance & Outlook
By using two low-cost, industrially produced solvents that were previously considered unsuitable, this research provides a new design principle that overturns conventional wisdom. The ability to achieve high performance without expensive materials could accelerate the commercialization of compact grid-scale energy storage and longer-range electric vehicles.
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