# Redox‐Mediated Electrochemical Regeneration of Spent LiFePO4 Battery Cathodes

## TL;DR

A new electrochemical method regenerates spent LiFePO4 battery cathodes using a redox mediator, achieving performance similar to new materials.

## Contribution

A scalable, redox-mediated electrochemical process for direct regeneration of LiFePO4 cathodes is introduced.

## Key findings

- The redox mediator Fe-PDTA enables electron transfer to repair degraded LiFePO4.
- The process achieves current densities up to 100 mA/cm² on a 100 g scale.
- Regenerated LiFePO4 matches the electrochemical performance of pristine material.

## Abstract

Direct recycling of lithium‐ion battery cathodes offers considerable appeal over metallurgical approaches. Here, we demonstrate a mediated electrochemical method for direct regeneration of degraded LiFePO4 (LFP). The approach uses a redox mediator, iron propylenediamine tetraacetate, that undergoes electrochemical reduction and is circulated through an external reservoir, where it supplies the electrons needed to regenerate LFP in the presence of Li+ ions derived from LiOH oxidation. Rapid outer‐sphere electron transfer is observed from the mediator to the degraded LFP material. This feature, together with good aqueous solubility of the mediator (0.3 M), supports current densities up to 100 mA/cm2, and this electrochemical recycling process is demonstrated on 100 g scale. 57Fe Mössbauer spectroscopy is used to monitor the correction of structural defects in the degraded LFP, providing the basis for regeneration of LFP that matches the electrochemical performance of pristine LFP.

This work demonstrates a redox‐mediated electrochemical method for direct recycling of spent LiFePO4 battery cathodes. A water‐soluble mediator, iron propylenediamine tetraacetate (Fe‐PDTA), transports electrons into an off‐electrode reservoir where it drives compositional and structural repair of degraded LiFePO4. This process achieves current densities up to 100 mA/cm2 and regenerates LiFePO4 with performance comparable to pristine material.