# Enhancing Solid Booster Utilization in Redox-targeted Flow Batteries with Non-fluorinated Binders

## TL;DR

This paper shows how using non-fluorinated binders improves the performance of redox-targeted flow batteries by boosting solid booster utilization.

## Contribution

The study introduces non-fluorinated, biodegradable binders that significantly enhance LiFePO4 conversion rates in redox-targeted flow batteries.

## Key findings

- Non-fluorinated binders like polycaprolactone and cellulose acetate increase LiFePO4 conversion rates by up to 175%.
- Higher solid booster utilization is directly linked to binder hydrophilicity.
- Improved performance is observed at cycling rates up to 10 mA cm–2.

## Abstract

Redox-targeted flow batteries (RTFBs) are promising for
large-scale
energy storage but suffer from poor solid booster utilization. This
study examines how binder selection affects the reaction rate between
a LiFePO4/FePO4 solid booster composite and
a dissolved [Fe­(CN)6]4–/3– redox
mediator. The porosity and hydrophilicity of LiFePO4 composites
correlate with booster utilization, determined by galvanostatic cell
cycling and by in situ UV–Vis spectroscopy.
Compared with state-of-the-art polyvinylidene difluoride composites,
booster pellets containing non-fluorinated, biodegradable polycaprolactone
or cellulose acetate binders exhibit up to 175% higher LiFePO4 conversion rates and improved capacity utilization at cycling
rates up to 10 mA cm–2. Solid-material utilization
directly correlates with binder hydrophilicity, establishing it as
a key design parameter for RTFBs and offering a straightforward path
toward more efficient and non-fluorinated booster formulations.