LAUSR

Abstract Online Electrochemical Mass Spectrometry (OEMS) provides unparalleled access to the details of electrode/electrolyte interfacial reactions in electrochemical systems. Herein, the development and validation of an OEMS system along with detailed calibration protocols and limits of detection sensitivity are showcased. Combined partial and total pressure monitoring provides a clear advantage when detailing major and minor gas reactions as well as when determining unaccounted gases. A classical Li-ion LiCoO2/Graphite full cell is studied during overcharge to 4.9 V vs. Li+/Li at 50 °C at an unprecedented level of detail and the results are compared to LiCoO2/LiFePO4 and Graphite/LiFePO4 cells in order to differentiate between gases forming at the anode and cathode. The release of O2 from LixCoO2 (x