Review—Chemical Analysis for a Better Understanding of Aging and Degradation Mechanisms of Non-Aqueous Electrolytes for Lithium Ion Batteries: Method Development, Application and Lessons Learned

Non-aqueous organic solvent based electrolytes solutions are state of the art components in lithium ion batteries. Numerous investigations have led to the structural, qualitative and quantitative information of the electrolyte degradation products and eventually resulted in the proposal of mechanisms for the related electrolyte aging reactions. To obtain more detailed and also more quantitative knowledge about the fundamental degradation processes, and to identify numerous degradation products and their structures, novel analytical techniques for chemical analysis were developed and systematic research of the decomposition products was performed by applying these new methods. In this mini-review, we introduce these techniques and how they can be applied for the chemical analysis of non-aqueous organic solvent and ionic liquid based electrolytes to gain a deeper knowledge of aging and degradation of electrolytes for lithium and lithium ion batteries.