Asymmetric Ether Solvents for High-Performance Lithium-Metal Batteries

Stanford researchers have developed a new class of asymmetric ether solvents — both non-fluorinated and fluorinated — for next-generation lithium-metal batteries. These innovative solvents, which include 1,2-methoxy ethoxy ethane (MEE) and its fluorinated derivatives (F1MEE, F2MEE, F3MEE), are synthesized via scalable methods from widely available chemical feedstocks and can serve as core components in advanced battery electrolytes.

Lithium-metal batteries promise much higher energy density than conventional lithium-ion batteries, but their commercial adoption has been hindered by poor cycling stability, low coulombic efficiency, and safety concerns stemming from unstable solid-electrolyte interphases (SEI) and dendrite formation. The inventors' new asymmetric ether solvents address these challenges by optimizing lithium-ion solvation and promoting the formation of stable, robust SEI layers. This results in electrolytes that deliver high coulombic efficiency (up to 99.5%), low overpotential, and exceptional cycling stability across a range of high-voltage and high-rate battery electrode chemistries — including LiFePO₄ (LFP), LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811), sulfurized polyacrylonitrile (SPAN), and silicon electrodes.

Notably, F3MEE-based electrolytes combine exceptional ionic conductivity with enhanced oxidative stability and enable robust operation in demanding applications such as electric vehicles, electric vertical take-off and landing (eVTOL) aircraft, and grid storage. This technology offers a practical, scalable pathway to safer, longer-lasting, and higher-performing lithium-metal batteries, unlocking new possibilities for energy storage and electrified transportation.

Stage of Development
Proof of concept — validated in laboratory-scale lithium-metal batteries.