Green and Efficient Strategy for Recycling Lithium-Ion Batteries

In a recent study published in Angewandte Chemie, researchers developed a novel approach to extract lithium and other valuable metals from neutral solutions. The method uses the hydrometallurgical process, which is low-cost, highly effective, and environmentally friendly. The addition of the amino acid glycine and a solid-solid reduction mechanism, called the battery effect, both increase the leaching efficiency.

Lithium-ion batteries are essential for powering smartphones, tablets, and electric cars, and are increasingly critical for storing erratic renewable energy. As their use grows, so does the number of spent batteries.

Recycling these batteries offers the potential to recover raw materials like lithium, cobalt, nickel, and manganese for the production of new rechargeable batteries. It also has the potential to reduce environmental impact.

Currently, hydrometallurgical reprocessing techniques for spent lithium-ion batteries rely on acid or ammonia-leaching processes. However, excessive and repeated use of acids and bases raises environmental concerns and safety risks. A pH-neutral procedure would be a safer, more environmentally friendly alternative.

The aggressive reagents required for traditional leaching methods are difficult to replace. To address this, the team led by Lei Ming and Xing Ou at Central South University, Zhen Yao at Guizhou Normal University, and Jiexi Wong at the National Engineering Research Center of Advanced Energy Storage Materials had to explore alternative solutions.

The first step in the process was the creation of "micro batteries" on the spot. These micro batteries assist in breaking down the lithium-coated nickel cobalt manganese oxide (NCM) cathode material from the spent batteries. The NCM particles are combined with sodium oxalate, an iron (II) salt, and the amino acid glycine in a neutral liquid.

This results in a thin, solid layer of iron(II) oxalate being deposited on the particles. The NCM cores act as the cathode, while the iron(II) oxalate “shell” serves as the anode (battery effect), allowing for easy electron transfer through direct contact.

Moreover, this coating prevents unwanted byproducts from adhering to the particles. An electrochemical reaction, fueled by the battery effect, reduces oxygen ions from the NCM particles to OH– ions with water, while iron (II) ions are oxidized to iron (III) ions.

As a result, the NCM layers break down, releasing the ions of manganese, nickel, cobalt, and lithium into the solution.

The second step involves the glycine "trapping" these ions in complexes. Glycine also helps to buffer the pH of the solution, maintaining it within a neutral range. After 15 minutes, 99.99 % of the lithium, 96.8 % of the nickel, 92.35 % of the cobalt, and 90.59 % of the manganese can be leached out of the spent cathodes.

This efficient, neutral solution-based leaching process could enable large-scale, environmentally friendly recycling of spent batteries. The glycine effluent can be used as fertilizer, and minimal toxic gases are produced. Compared to traditional methods, this process is cheaper and consumes significantly less energy.

Journal Reference:

Xu, Z., et al. (2025) A Green and Efficient Recycling Strategy for Spent Lithium‐Ion Batteries in Neutral Solution Environment. Angewandte Chemie International Edition. doi.org/10.1002/anie.202414899.