# Recycling of High-Purity Lithium Metal from Waste Battery by Photoelectrochemical Extraction at Ultralow Overall Potential

## TL;DR

This paper introduces a solar-powered method to efficiently extract high-purity lithium metal from waste batteries using a photoelectrochemical system.

## Contribution

The study presents a novel low-potential PEC system for selective and efficient lithium extraction with high purity and Faradaic efficiency.

## Key findings

- The PEC system achieved a lithium extraction rate of ~1.38 g h−1 m−2 with 90.7% Faradaic efficiency.
- The extracted lithium metal had a purity of 99.5%.
- The system also showed potential for purifying waste electrolytes and recycling other metals like Fe, Co, and Ni.

## Abstract

A low-potential photoelectrochemical (PEC) system was designed and used to selectively and efficiently extracts Li metals from multi-cation electrolytes under 1 sun illumination.A coplanar Si-based photocathode-TiO2 photoanode PEC device exhibited an acceptable extraction rate of ~1.38 g h−1 m−2, an excellent FE of 90.7% and a high production purity of 99.5%.The designed PEC system also showed potential for purifying the waste electrolytes and recycling the other metals (i.e., Fe, Co, and Ni).

A low-potential photoelectrochemical (PEC) system was designed and used to selectively and efficiently extracts Li metals from multi-cation electrolytes under 1 sun illumination.

A coplanar Si-based photocathode-TiO2 photoanode PEC device exhibited an acceptable extraction rate of ~1.38 g h−1 m−2, an excellent FE of 90.7% and a high production purity of 99.5%.

The designed PEC system also showed potential for purifying the waste electrolytes and recycling the other metals (i.e., Fe, Co, and Ni).

The online version contains supplementary material available at 10.1007/s40820-025-01958-z.

To ease the scarcity of lithium (Li) resource and cut down on environmental pollution, an efficient, selective, inexpensive and sustainable Li recycling process from waste batteries is needed, which is yet to be achieved. Here, we report a low-potential photoelectrochemical (PEC) system that selectively and efficiently extracts Li metals from multi-cation electrolytes under 1 sun illumination. Based on the difference of redox potential, we can get rid of the disturbance of other cations (i.e., Fe, Co and Ni ions) by a bias-free PEC device to realize the extraction of high-purity Li metals on a coplanar Si-based photocathode-TiO2 photoanode tandem device at 2 V of applied bias (far less than the redox potentials of Li+/Li). In such system, the extraction rate of Li metals (purity > 99.5%) exceeds 1.35 g h−1 m−2 with 90% of Faradaic efficiency. Long-term experiments, different electrode/electrolyte tests, and various price assessments further demonstrate the stability, compatibility and economy of PEC extraction system, enabling a solar-driven pathway for the recycling of critical metal resources.

The online version contains supplementary material available at 10.1007/s40820-025-01958-z.