# Politecnico di Milano tests room-temperature fluoride battery membrane in coin cells

- Published: 2026-11-07 04:55 UTC
- Section: Power & Energy › Batteries
- Tags: fluoride-ion battery, quasi-solid polymer electrolyte, Politecnico di Milano, room temperature battery, fluoride exchange membrane
- URL: https://realtech.media/news/rt-661b8671f9091dd17ec6597b_politecnico_di_milano/

**A quasi-solid polymer electrolyte achieved 1.3 × 10⁻³ S cm⁻¹ ionic conductivity at room temperature, completing over 50 cycles in a prototype cell.**

![Politecnico di Milano tests room-temperature fluoride battery membrane in coin cells](https://realtech.media/media/2026/11/0617503cd03c5dc6.jpg)
*Farizat Aidyn, Wikimedia Commons, CC BY-SA 4.0*

Researchers from the Department of Chemistry, Materials and Chemical Engineering at Politecnico di Milano have developed a quasi-solid polymer electrolyte for fluoride-ion batteries, according to a study published in Energy Storage Materials. The prototype system operates at room temperature, addressing a key limitation of previous fluoride-ion designs that required heating to 100–150 °C to achieve sufficient conductivity. During laboratory experiments, the team demonstrated stable cycling performance exceeding 50 cycles in a standard coin-cell format [1].

Fluoride-ion batteries provide an alternative to lithium-based systems by using more abundant raw materials and non-flammable components. However, practical implementation has been held back by low ionic conductivity in solid-state electrolytes at ambient conditions. The Italian researchers formulated a fluoride-exchange membrane based on a perfluorosulfonic amide ionomer functionalized with tetraalkylammonium fluoride groups. The polymer matrix was swollen using a binary solvent mixture containing 1,3-dioxolane and dimethyl sulfoxide, which enhanced ion mobility without compromising phase stability [1].

## Transport mechanisms and performance

Molecular dynamics simulations confirmed that dimethyl sulfoxide functions as a polar swelling agent within the membrane network, facilitating the dissociation and migration of fluoride ions. Electrochemical impedance spectroscopy showed that the prepared membrane achieved an ionic conductivity of up to 1.3 × 10⁻³ S cm⁻¹ at room temperature [1]. According to the authors, the theoretical energy density of fluoride-ion systems can reach approximately 600 Wh/kg, compared with 150–250 Wh/kg typical of conventional lithium-ion cells.

## Electrode reversibility

To verify electrochemical stability, the team assembled test cells with lead and lead fluoride electrodes. Galvanostatic charge-discharge tests confirmed reversible fluorination and defluorination reactions at ±0.8 V under a current density of 0.1 C [1]. The researchers reported that the non-flammable quasi-solid electrolyte sustained reversible transport throughout testing, providing an experimental basis for solid-state fluoride energy storage without the need for auxiliary heating systems.

## Sources

1. [Energy storage materials](https://doi.org/10.1016/j.ensm.2026.105410)
2. [EurekAlert](https://www.eurekalert.org/news-releases/1150799)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-661b8671f9091dd17ec6597b_politecnico_di_milano/