(Invited) Recycling of Used Li-Ion Batteries By Innovative Electrodialysis Using New Lithium Ionic Conductor Membrane

Abstract

As a means of addressing global warming, the world is increasingly turning to the use of Li-ion batteries in electric vehicles and as storage batteries in the home; therefore, there is a growing need for Li. I have developed a method for the recovery of Li from used Li-ion batteries using a Li ionic conductor functioning as a Li-ion separation membrane (LISM). This innovative method involves the use of an LISM whereby only Li ions in a solution of used Li-ion batteries permeate from the positive electrode side to the negative electrode side during electrodialysis; the other ions, including Co, Al, and F, do not permeate the membrane. Li0.29La0.57TiO3 was selected as the LISM. The positive side of the dialysis cell was filled with used Li-ion battery solution. Then the negative side was filled with distilled water. The applied dialysis voltage was 5 V, and electrode area was 16 cm2. The Li recovery ratio increased with electrodialysis time. Then, Co, Al, and F were not permeated (Fig.1). Measurements of the Li ion concentration at the negative electrode side as a function of dialysis duration showed that the Li recovery ratio increased to approximately 90% after 72 h. Moreover, other ions in the seawater did not permeate the LISM. With both ends of the LISM bound with a negative and positive electrode, hydrated Li ion was transformed to Li ion only because Li ion can permeate through the LISM [1]. After electrodialysis, CO2 gas was bubbled in the Li recovery water to produce lithium carbonate (Li2CO3) as a raw material for Li-ion batteries. The Li2CO3 deposition was easily generated by the reaction of CO2 gas and the Li recovery solution as a lithium hydroxide (LiOH) solution (Fig.2). Moreover, the purity of Li2CO3 is up to 99.99%. This new method for recycling Li-ion batteries shows good energy efficiency and is easily scalable. Thus, this electrodialysis method is suitable for the recycling of Li from used Li-ion batteries. Fig.1 Schematic of Li recovery from Li-ion battery solution using the proposed electrodialysis. Fig.2 Production of High-purity Li2CO3 by CO2 bubbling method. [1] T. Hoshino, Desalination, 359, 59-63 (2015). Figure 1