Lithium recycling: Researchers find a pocket and eco-friendly way

Using a mechanochemical approach to recycling

Conventionally, metal recovery is attempted largely using metallurgical methods. This often means that a large amount of energy needs to be spent to recover the material. Adding chemicals to the process can reduce the amount of energy required but often leads to the production of a hazardous by-product.

A collaboration between the researchers at KIT's Energy Storage Systems Department and Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU) in Germany used a mechanochemical approach for the recovery of lithium.

In such an approach, mechanical processes are used to bring about chemical reactions that give much higher yields of desired products while consuming lesser energy and improving sustainability.

While previous attempts at lithium recovery have required the prior sorting of materials, the new approach can be applied to the batteries directly, making it much more efficient.

In this approach, the researchers at KIT and their collaborators used aluminum as a reducing agent. Since aluminum is already contained in the cathode of lithium-ion batteries, it does not have been added externally.

The recovery process is also quite simple. The battery first needs to be ground where the material reacts with aluminum to form metallic composites. Lithium, which is water soluble, is recovered by mixing water with the ground mixture and then heating it separately to make the water evaporate.

The researchers found that up to 70 percent lithium recovery can be achieved with this method, which does not require the use of corrosive chemicals or high temperatures. Since most of the process happens at normal room temperature and pressure, it is highly efficient.

Going forward, the method is also scalable and can be deployed at an industrial scale when a large number of batteries become available.

The research findings were published in the journal Communications Chemistry.

Study abstract:

The increasing lithium-ion battery production calls for profitable and ecologically benign technologies for their recycling. Unfortunately, all used recycling technologies are always associated with large energy consumption and utilization of corrosive reagents, which creates a risk to the environment. Herein we report a highly efficient mechanochemically induced acid-free process for recycling Li from cathode materials of different chemistries such as LiCoO2, LiMn2O4, Li(CoNiMn)O2, and LiFePO4. The introduced technology uses Al as a reducing agent in the mechanochemical reaction. Two different processes have been developed to regenerate lithium and transform it into pure Li2CO3. The mechanisms of mechanochemical transformation, aqueous leaching, and lithium purification were investigated. The presented technology achieves a recovery rate for Li of up to 70% without applying any corrosive leachates or utilizing high temperatures. The key innovation is that the regeneration of lithium was successfully performed for all relevant cathode chemistries, including their mixture.