Degradation Pathways of Carbonate‐Based Electrolyte Formulations in Potassium Vanadium Phosphate/Graphite Potassium‐Ion Batteries

Electrolyte development for potassium-ion batteries (KIBs) pose great challenges due to the high intrinsic reactivity of the K-ion system as well as the desired high-voltage application of KIBs, which often trigger strong decomposition of the electrolyte at the electrode interfaces. A common approach to tailor the electrolyte's properties is the use of cosolvents and additives. While their role in lithium- and sodium-based systems is progressively elucidated and even become established as standard cell components, the impact in KIBs still demands for a fundamental investigation. In this study, a comparative analysis of K-ion full cells based on a potassium vanadium phosphate cathode (KVP/C) and a graphite anode employing several electrolyte formulations was carried out to shed light on the complex interrelations of cyclability and the use of prevalent electrolyte additives. Thereby, vinylene carbonate (VC) was determined as most promising additive for next-generation high-voltage KIBs.