Transition Metal Dissolution in Lithium-Ion Cells: A Piece of the Puzzle
Seoung‐Bum Son, Zhengcheng Zhang, Jihyeon Gim, Christopher S. Johnson, Yifen Tsai, Michael Kalensky, Susan Lopykinski, Özgenur Kahvecioğlu, Zhenzhen Yang, Anthony T. Montoya, Ira Bloom
Abstract
Static leaching tests were performed using the chemically delithiated positive electrode materials, LiFePO 4, LiCoO 2, LiMn 2 O 4, LiNiO 2, and LiNi 0.8 Mn 0.1 Co 0.1 O 2 . Instead of the common electrolyte, which contains LiPF 6, the solvent consisted of only ethylene carbonate (EC) and ethyl methyl carbonate (EMC), limiting the possible reactions to only those that depend on the solvent. The product liquids from these experiments showed that there were lithium-bearing species in common, such as Li(EC) + and Li(EMC) + . Interestingly, we found evidence of electrolyte degradation products in both the positive- and negative-ion mass spectral results. The positive-ion results showed that the products tended to coordinate to lithium. The negative-ion results showed that most of the products tended to complex with transition metals. It was difficult to discern which positive ion was associated with which negative ion.