Identification of Electrolyte Salts in Lithium-Ion Battery Black Mass

Abstract

Based on ion chromatographic and thermal analyses, it was demonstrated that the assumption that the presence of PF₆^– ions in lithium-ion battery (LIB) black mass is due to LiPF₆ residues is incorrect. In the industrial samples investigated, PF₆^–-containing residues were present in the case of low temperature-pretreated LIB black mass. Based on thermal analysis, a significant proportion of the PF₆^– species was found to originate from NaPF₆. The presence of NaPF₆ is due to the use of tap water in the commercial workup process. Due to the transformation of the PF₆^– species and the associated changes in degradation and hydrolysis behavior, appropriate recycling routes need to be adapted regarding the handling of the conducting salt.