High-Performance Electrolytes for Lithium Metal Batteries

Lithium metal batteries present an avenue for achieving exceptionally high energy densities but face challenges arising from unstable electrolyte–electrode interfaces, limited electrochemical windows and uneven lithium deposition. High-performance electrolytes for these systems aim to stabilise the lithium metal anode, suppress dendritic growth and enable compatibility with high-voltage cathodes. Strategies span solvent design—ranging from fluorinated ethers to monofluoride analogues—salt selection and concentration modulation to engineer solvation structures that foster robust solid-electrolyte interphases (SEIs) and cathode-electrolyte interphases (CEIs). Recent advances demonstrate that tailoring solvent molecular architecture can enhance oxidation stability beyond 4.5 V while maintaining high ionic conductivity and facilitating rapid ion transport at low temperatures. Moreover, concentrated and pseudo-oversaturated formulations have been developed to yield inorganic-rich SEIs that promote uniform lithium nucleation and long cycle life. Collectively, these approaches are converging towards electrolytes that combine high voltage tolerance, fast-charging capability and safety—essential hallmarks for the next generation of electric vehicles and grid-scale storage.

Research from Nature Portfolio

Recent studies have reported a monofluoride ether solvent that achieves Li–F and Li–O tridentate coordination, combining wide electrochemical stability with enhanced ionic conductivity. This electrolyte supports fast charging at high current densities and stable cycling over a broad temperature range (−60 °C to +60 °C), enabling pouch cells with specific energies exceeding 420 Wh kg⁻¹ and 80 per cent capacity retention after 200 cycles. Targeted trifluoromethylation of ether solvents has also been shown to balance electrolyte conductivity and oxidation resistance. A 2 M solution of lithium bis(fluorosulfonyl)imide in a trifluoro-substituted dimethoxypropane solvent yielded oxidation stability up to 4.8 V, ionic conductivity above 7 mS cm⁻¹ at 25 °C and high retention in high-loading LiNi₀.₈Co₀.₁Mn₀.₁O₂ cells. More recently, a molecular anchoring approach has been introduced in diluted ether electrolytes, where hydrogen-bonding solvents suppress free solvent reactivity. This strategy stabilises nickel-rich cathodes at 4.7 V, mitigates thermal runaway and maintains battery safety under abuse conditions, signalling a new pathway to high-voltage compatibility without resorting to extreme salt concentrations.

High-Performance Electrolytes for Lithium Metal Batteries publication trend

The graph below shows the total number of articles in high-performance electrolytes for lithium metal batteries across all publications each year (not limited to Nature Index journals).

Technical terms

Solvation structure: The arrangement of solvent molecules and anions around a lithium ion, influencing electrolyte conductivity and interphase formation.

Solid-electrolyte interphase (SEI): A passivating layer on the lithium metal surface formed by electrolyte decomposition, critical for cycling stability and dendrite suppression.

Cathode-electrolyte interphase (CEI): A protective interface at the positive electrode that prevents solvent oxidation and maintains electrode integrity at high voltages.

Pseudo-oversaturated electrolyte (POSE): An electrolyte formulation in which inert diluents allow higher salt-to-solvent ratios than solubility limits suggest, enhancing interphase stability.

Hydrogen-bonding anchoring: A strategy that uses solvent molecules with hydrogen-bond donors to immobilise free solvent, reducing side reactions and improving voltage tolerance.

References

1. Demystifying the Salt-Induced Li Loss: A Universal Procedure for the Electrolyte Design of Lithium-Metal Batteries. Nano-Micro Letters (2023).
2. Long‐life lithium batteries enabled by a pseudo‐oversaturated electrolyte. Carbon Energy (2023).
3. A monofluoride ether-based electrolyte solution for fast-charging and low-temperature non-aqueous lithium metal batteries. Nature Communications (2023).
4. Electrolyte engineering via ether solvent fluorination for developing stable non-aqueous lithium metal batteries. Nature Communications (2023).
5. Molecular anchoring of free solvents for high-voltage and high-safety lithium metal batteries. Nature Communications (2024).
6. Ultra‐Low Concentration Electrolyte Enabling LiF‐Rich SEI and Dense Plating/Stripping Processes for Lithium Metal Batteries. Advanced Science (2022).