New Technology Effectively Recycles Lithium Battery Waste, Minimizing Pollution with High Benefits

The demand for lithium metal continues to increase, but mining, extraction, and recycling of lithium metal can all lead to environmental pollution. Using environmentally friendly recycling methods can pose challenges due to potential cost inefficiencies. Recently, a university in the United States has developed an efficient and low-energy method for lithium recycling, which can reduce the pollution caused by chemical recovery processes.

At the core of lithium batteries lies lithium metal, which is used in electronic products, electric vehicles, and even energy storage systems for power grids. According to some statistics, the global market value of lithium batteries was estimated to be around $500 to $600 billion in 2023, and it is projected to grow to over $1 trillion in the next decade.

However, as the lithium battery market continues to expand, there may be a risk of supply shortages of the commonly used lithium (Li), cobalt (Co), and nickel (Ni) metals. As a result, some are turning their attention to discarded lithium batteries, hoping to recover metals for reuse.

While traditional lithium battery recycling methods are economically feasible, the use of leaching agents such as strong acids, strong reducing agents, or corrosive agents can pose environmental pollution risks. Past attempts at wet metallurgical recovery using low-melting solvent (DES) with less environmental impact have only been able to recover less than 5% of lithium, which does not meet economic viability. Therefore, most recycling operators have focused on transition metals like cobalt and nickel.

In late June, a new research study was published in the journal “Advanced Functional Materials”: Rice University in the United States placed discarded lithium batteries into a specially designed DES solvent and used microwave radiation for heating, allowing the solvent to selectively recover lithium metal efficiently.

The research team chose DES solvent because it can extract and separate different target components from various samples, offering environmental friendliness, simple preparation, low cost, and easy biodegradability.

By mixing choline chloride (ChCl) and ethylene glycol (EG) in a 3:2 ratio to create the DES solvent, and using microwave radiation for heating assistance, lithium metal could be extracted in just 30 seconds with an efficiency of up to 50%. Within 30 minutes, the extraction rate approached 100%.

The choice of choline chloride and ethylene glycol facilitates the formation of hydrogen bonds in cobalt and nickel oxides, which then form soluble chlorometallic acid salts with chloride ions in choline chloride.

Moreover, choline chloride has a microwave-absorbing property. By immersing battery waste into the solvent and using microwave-assisted heating, researchers were able to accelerate lithium extraction in 30 seconds without the need for additional reducing agents.

In addition, microwave radiation reduces particle aggregation, promotes the formation of large pores and cracks, increases the contact surface area between battery waste and DES solvent, thereby speeding up metal extraction.

Researchers found that this microwave-based process achieved an extraction rate of 87% in just 15 minutes, compared to traditional oil bath heating methods which required 16 to 18 hours to achieve the same recovery rate.

Furthermore, with the microwave-based process, after 30 minutes of reaction, lithium, cobalt, and nickel extraction efficiencies were 96.6%, 37.2%, and 31.5%, respectively. This method also exhibited selective lithium extraction at temperatures ranging from 160°C to 180°C, with better performance at 220°C.

This rapid microwave method not only reduces time and energy consumption, improves recycling efficiency, but also prevents premature degradation of DES due to prolonged heating, prolonging its lifecycle. This advances the economic viability and environmental impact of lithium battery recycling, providing a sustainable solution.

This method can also be applied to DES systems with different compositions to attempt rapid extraction of other types of metals, granting DES systems selectivity for specific metals.

One of the main authors of the paper, Salma Alhashim, a doctoral student at Rice University, explained, “The low recovery rate of lithium batteries is due to other metals in battery waste precipitating first, followed by lithium metal. Here, we mix choline chloride and ethylene glycol to create the DES solvent, allowing lithium metal to be quickly extracted once surrounded by chloride ions in choline chloride.”