Detection of protons using the rotating ring disk electrode method during electrochemical oxidation of battery electrolytes

Knowledge of the degradation mechanisms inside lithium-ion batteries (LIBs) is critical in designing robust next-generation materials. While significant efforts have led to advances in characterization techniques and in our general understanding of the numerous decomposition reactions, the complex, multicomponent nature of batteries has hindered our progress towards developing a complete picture of these processes. In this work, we present a method for the detection of protons—one of the commonly proposed products of battery electrolyte decomposition at high potentials—using the rotating ring disk electrode (RRDE) method. Using the H2 oxidation reaction (HOR) as a model reaction, we first determine that protons generated at the disk electrode can be detected in organic carbonate-based electrolyte at the ring electrode with a ring collection efficiency close to the theoretical value. We then show that protons are indeed generated during the electrochemical decomposition of the battery electrolyte on Pt(1 1 1) at high potentials. Furthermore, quantitative detection of protons provided a valuable insight into the mechanism of oxidation for the electrolyte used. Overall, our work demonstrates the value of RRDE as a complementary method for studying potential-dependent electrolyte stability.