New Fluorinated Electrolyte Boosts High-Voltage Lithium Battery Performance

Researchers develop an all-fluorinated electrolyte that stabilizes cobalt-free LNMO cathodes for next-gen electric vehicle batteries.

Feb. 26, 2026 at 2:16am

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A team of researchers led by the University of California, Irvine has developed an all-fluorinated electrolyte (AFE) that can stabilize high-voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes, a promising cobalt-free alternative for electric vehicle batteries. The new electrolyte, which combines fluorinated solvents with a boron-containing additive, forms a robust Cathode-Electrolyte Interphase (CEI) layer that prevents oxidation and degradation, allowing LNMO cells to retain 84.1% of capacity after 250 cycles at 4.9V.

Why it matters

As the demand for electric vehicles grows, there is a pressing need to develop batteries with higher energy density, lower costs, and reduced reliance on scarce materials like cobalt. LNMO cathodes offer a potential solution, but their commercial adoption has been hindered by instability issues with standard electrolytes. This new all-fluorinated electrolyte breakthrough could help unlock the potential of LNMO and accelerate the development of more powerful, longer-lasting EV batteries.

The details

The researchers replaced traditional solvents with fluorinated counterparts and added a boron-containing additive (TMSB) to create the new all-fluorinated electrolyte (AFE). Fluorinated solvents have special chemical properties that make them resistant to oxidation, allowing the electrolyte to withstand voltages up to 6.5V without decomposing. The key is the formation of a robust Cathode-Electrolyte Interphase (CEI) layer rich in fluorine and boron, which acts as a protective 'skin' to prevent side reactions and cathode dissolution.

  • The study's findings were published in the journal Energy Materials and Devices on December 1, 2025.
  • In comparative tests, Li//LNMO cells using the new AFE retained 84.1% of their capacity after 250 cycles at a high cut-off voltage of 4.9V.

The players

Huolin Xin

A researcher at the University of California, Irvine who led the team that developed the new all-fluorinated electrolyte.

Peichao Zou

A former postdoctoral researcher in Xin's research group who helped design the new electrolyte formulation.

Lulu Ren

A former postdoctoral researcher in Xin's research group who discussed the next steps for optimizing the electrolyte.

LNMO

Spinel LiNi 0.5 Mn 1.5 O 4, a cobalt-free cathode material that offers high operating voltage but has faced issues with electrochemical instability.

AFE

The all-fluorinated electrolyte developed by the research team to stabilize LNMO cathodes.

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What they’re saying

“To boost the energy density of batteries, we need to push the voltage limits. But conventional electrolytes are like using an oil that burns off when the engine gets too hot—they simply oxidize and decompose at voltages above 4.2 V.”

— Peichao Zou, Former postdoctoral researcher

“Think of the CEI layer as a protective skin that forms on the cathode. With standard electrolytes, this skin is weak and keeps breaking, consuming the battery's fluid. Our fluorinated electrolyte builds a tough, stable armor that stops side reactions and prevents the metal structure of the cathode from dissolving.”

— Peichao Zou, Former postdoctoral researcher

“This study presents a facile and effective approach to promoting the commercialization of high-voltage LNMO cathodes. Our next steps involve optimizing the formula to improve low-temperature conductivity and fast-charging capabilities, ensuring these batteries are ready for all-climate applications.”

— Lulu Ren, Former postdoctoral researcher

What’s next

The researchers plan to further optimize the all-fluorinated electrolyte formula to improve low-temperature conductivity and fast-charging capabilities, ensuring the technology is ready for all-climate electric vehicle applications.

The takeaway

This breakthrough in all-fluorinated electrolyte technology represents a significant step forward in unlocking the potential of high-voltage LNMO cathodes, a promising cobalt-free alternative for next-generation electric vehicle batteries that could boost energy density, lower costs, and reduce reliance on scarce materials.