Low-cost recovery of ultra-high purity lithium achieved by QST using used batteries

The research team of Senior Principal Researcher Tsuyoshi Hoshino of the National Institutes for Quantum Science and Technology Fusion Energy Directorate Rokkasho Fusion Institute, Proliferation Functional Materials Development Group, has realized the low cost recovery of ultra-high purity lithium (Li) as a battery material from in-vehicle lithium-ion batteries (LIBs) through an ultra-high purity (99.99%) Li recovery technology, using the Li separation method by ionic conductor (LiSMIC) technology which allowed for the development of a high-performance ionic conductor as a Li separation film.

Li is an essential substance for producing tritium, which is a fuel for fusion reactors. In Japan, by 2027-2030, securing sufficient amounts of Li is predicted to be challenging owing to the increase in the number of electric vehicles (EVs) in recent years. Therefore, the research team has been conducting research and development on Li resource recovery using LiSMIC technology. The research team evaluated the Li recovery cost of the developed Li ion conductor. To achieve this, they developed a new Li recovery device that could stack 20 ion conductors, be operated continuously for several weeks, and search for the optimum conditions for Li recovery.

To test this Li recovery device, the black powder (battery ash) obtained by heat-treatment (roasting) of the used LIBs was immersed in water. Then, 50 liters of the water leachate was used as a stock solution, and the optimum conditions for the voltage to be applied, temperature of the solution, and flow velocity in the device were determined. Furthermore, a high-performance ion conductor was subjected to surface Li adsorption treatment for 14 days. The results of this treatment for continuous Li recovery showed an increase in the recovery rate that was significantly higher (approximately 13 times) than that when using a conventional ion conductor; furthermore, the Li recovery rate achieved in the case of the former was stable.

The cost of manufacturing lithium hydroxide from water leachate was calculated based on these results. Lithium hydroxide (2,000 tons/year), which is the raw material for batteries, could be manufactured at a production cost of less than half that of the import price (average import price of ¥1287/kilogram; 2020 trade statistics). Furthermore, by increasing the Li concentration in the water leachate to the maximum concentration at which Li in the black powder dissolves, and by improving the Li recovery rate, it was possible to determine the potential for recovery at a manufacturing cost of less than half the import price. For Japan, which relies 100% on overseas imports of Li, this achievement has opened up the prospect for future domestic resource recycling.

According to Senior Principal Researcher Dr. Hoshino, "LiSMIC can be applied to the industrial recycling of large in-vehicle lithium-ion batteries, which has been considered difficult in terms of cost. In the future, we will demonstrate the technology on a pilot plant scale with larger equipment, and through the stable supply of ultra-high purity lithium, we will contribute greatly to the spread of EVs, which hold the key to carbon neutrality. In Europe, the mandatory recycling of used lithium-ion batteries is being considered, and the recycling movement is accelerating. We would like to contribute to the circular economy of lithium-ion batteries in Japan and overseas."