Selective recovery of lithium from thermally pretreated Li-ion batteries by the leaching process

Abstract: LIBs have become an ideal choice in the EVs batteries and stationary storage applications due to their invaluable advantages. The demand for LIBs is projected to increase due to the growth in the sale of EVs. But an average lifespan of LIBs is expected to be around 8 years, thus resulting in the generation of a huge pile of spent batteries after their end of life. The disposal of spent LIBs has several environmental impacts and also results in the loss of valuable metals as a waste. So, efficient, and sustainable recycling methods should also grow at the same pace as of the EVs industries. Li is one of the vital elements for the modern energy revolution and there is a growing demand for its usage in the battery applications. High demand for Li along with supply risks due to its uneven distribution in different geographical locations will increase the Li price. Also, Li was added to the list of EUs critical materials. Currently, only 1% of Li from the end of life products is being recovered. The hydrometallurgy processes based on acid leaching followed by recovery steps are found to be efficient in the recovery of a considerable amount of Li yet there are many drawbacks. Therefore, a combined method such as a thermal treatment followed by water leaching is found to be a promising route to first selectively separate Li from the other valuable metals. The purpose of this research is to investigate the selective leaching of Li from thermally pretreated waste LIBs (by pyrolysis and incineration processes between 400 – 700 ºC for 30, 60, 90min) with water as a leaching agent at high temperature and low L/S ratio. Al salts were also leached along with Li with an efficiency not higher than 3.5%. The finding showed that the time of thermal pretreatment did not have a significant change in Li leaching efficiency. The effect of the S/L ratio showed that the leaching efficiency of Li was higher with an increase in liquid content, keeping the mass of solid constant. At a higher leaching temperature, the leaching efficiency of Li was higher due to an increase in the solubility of Li salts. The highest Li leaching efficiency of nearly 60% was observed from the sample pyrolyzed at 700 ºC for 60 min with the leaching condition S/L ratio = 1:20 g/mL, 80 ºC, 300 rpm, 3 hrs. Furthermore, the tests such as addition of 10% excess carbon during thermal treatment or use of carbonated water during leaching were carried out to enhance the leaching efficiency of Li. However, the test results did not have a significant increase in the leaching efficiency of Li.