French Researchers (PROMES-CNRS Lab) Invent Solar Pyrolysis To Recycle Lithium Batteries

Research conducted at the PROMES-CNRS laboratory, under the leadership of Gilles Flamant, has recently validated the viability of employing a solar-powered pyro-metallurgical process for recycling valuable elements such as lithium, nickel, cobalt, and others from lithium-ion batteries. The PROMES-CNRS laboratory specializes in endeavors aimed at industrial decarbonization through the utilization of extremely high-temperature solar energy.

PROMES-CNRS lead Gilles Flamant asserts that with the anticipated surge in lithium-ion battery disposal over the coming decades, there is a pressing need for effective treatment methods, wherein solar thermal technology could significantly contribute to industrial decarbonization efforts.

For years and decades industries such as steel, cement, chemicals etc. have relied on fossil fuels, making fossil heat the established norm in these sectors. This poses a significant obstacle for concentrated solar power technology. However, the emergence of lithium-ion battery recycling, particularly through pyro-metallurgy, offers a promising avenue for concentrated solar heat to rival fossil-fuelled heat. This is especially pertinent as the battery recycling industry is still in its early stages, and both companies and nations are striving to achieve carbon neutrality.

Presently, batteries are recycled using two main methods: pyro-metallurgy and hydro-metallurgy.

Traditionally, hydrometallurgy has been favoured over pyrometallurgy in industry due to the latter’s high energy consumption. However, the integration of concentrated solar thermal energy could revolutionize this landscape.

The research team successfully harnessed high-temperature solar energy to generate a metal alloy comprising lithium, cobalt, nickel, and manganese (iron), as detailed in their paper titled “A Solar Pyro-Metallurgical Process for Li-ion Batteries Recycling: Proof of Concept,” published by PROMES.

Lithium-ion batteries consist of key components including the anode, cathode (current collectors), separator, and electrolyte, containing crucial metals like lithium, cobalt, and nickel primarily in the cathode.

How New Technology Works

The team at PROMES conducted a proof-of-concept test using a 1.5 kW solar furnace to explore solar pyrolysis for recycling strategic metals from lithium-ion batteries, marking the first successful demonstration of this pyrometallurgical process utilizing solar energy.

The process begins with thermal pre-treatment through solar pyrolysis at 580°C for 30 minutes to eliminate binders, organic impurities, and separate electrode materials, including copper and aluminum foils.

Following this, mechanical separation is employed to extract metallic foils and pyrolysis products from the cathode, resulting in a residue known as the “black mass.”

The black mass undergoes carbothermal reduction at 1000°C for 30 minutes, combining with graphite from the anode to create a Ni-based alloy.

Utilizing a 1.5 kW reactor at PROMES, a beam-down system reflects sunlight onto a parabolic surface, concentrating solar radiation onto a reaction chamber below.

This proof of concept marks the initial endeavor to utilize solar energy for such processes, with future steps including the separation of lithium from cobalt and nickel, refining smelting temperatures, engineering a continuous process, exploring reaction mechanisms, and mitigating pollutant emissions.

The proponents of the new technology envision the proliferation of midsize or smaller solar battery recycling plants across Southern Europe, leveraging the region’s ample solar resources. These facilities could be dispersed throughout the counties of Europe and elsewhere aligning with the PROMES technology and the concentrated solar prevalent in the area.