# Acid-Free Electrochemical Regeneration of Sandrose-like Aluminum Layered Double Hydroxide Electrodes for Selective Lithium-Ion Recovery in Mixed Ion Solution

## TL;DR

This paper introduces a new eco-friendly method for recovering lithium ions using a special aluminum material that works efficiently without harsh chemicals.

## Contribution

A novel acid-free electrochemical method for selective lithium-ion recovery using aluminum layered double hydroxide electrodes is introduced.

## Key findings

- Al-LDH electrode achieved 57.6 mg/g lithium ion adsorption capacity, significantly higher than Al(OH)3.
- The method operates under pH-neutral conditions, avoiding harsh chemicals and reducing environmental impact.
- Al-LDH shows high selectivity for lithium ions over sodium ions, making it suitable for mixed ion solutions.

## Abstract

The demand for lithium production has seen a significant
rise,
with the growing electric vehicle and stationary battery markets requiring
further development of sustainable and scalable extraction methods.
Direct lithium extraction technologies have been developed to address
potential shortages, with adsorption emerging as a key method due
to its efficiency and low environmental impact. Given that Al­(OH)3 is already utilized as an adsorbent in various industrial
applications, the practical importance of Al-based alternative systems
for lithium ion extraction is increasing, yet lithium ion recovery
requires harsh chemicals. In this study, we report a novel lithium
extraction method combining chemical adsorption and electrochemical
release using a synthesized aluminum layered double hydroxide (Al-LDH)
material, developed under mild reaction conditions. The performance
of the Al-LDH electrode was evaluated against a commercial Al­(OH)3 adsorbent. Comprehensive characterization using techniques
such as X-ray diffraction, Fourier-transform infrared spectroscopy,
and scanning electron microscopy revealed detailed insights into the
crystalline structure, particle size distribution, and surface morphology
of the materials. The Al-LDH electrode exhibited a lithium ion adsorption
capacity, achieving an average chemical uptake of lithium ions of
57.6 mg/g. In contrast, lithium-ion uptake capacity for Al­(OH)3 was 1.0 mg/g over 15 cycles. Notably, this method operates
under pH-neutral conditions, eliminating the need for harsh acidic
or basic eluents. As a result, it prevents structural degradation
and minimizes secondary pollution for potential future applications
of lithium-ion recovery. The material’s layered structure selectively
allowed lithium ion intake while blocking sodium ions, demonstrating
its high selectivity and utility in lithium ion recovery processes.
The integration of pH-neutral regeneration and high selectivity shows
that Al-LDH electrodes as viable candidates for next-generation, green
lithium extraction technologies.