Mediator Catalyst for Lithium Fluoride Decomposition for Lithium Recovery

A catalyst to electrochemically decompose lithium fluoride (LiF), which is abound in the electrode of the spent LiBs, was studied to develop a Li reproduction technology. Since the oxidizing activity of halogen I2, Br2, Cl2, or F2, increases, the reaction I2 + 2LiF → F2 + 2LiI cannot proceed. We examined the catalytic activity of interhalogens such as iodine monobromide (IBr) and iodine chloride (ICl) for LiF decomposition in specific organic solvents. We observed the chemical decomposition of LiF in IBr and ICl dimethyl sulfoxide (DMSO) solutions. This decomposition was induced by an increase in solution acidity, accompanied by a large deviation in the electric charge between two halogen elements due to the complex formation of interhalogen with DMSO. A double-chamber-type cell for Li recovery from LiF was constructed by combining this LiF decomposition behavior with redox coupling of IBr or ICl operated by electrical charging. The cell was first demonstrated to be chargeable due to the continuous decomposition of LiF.