Ion Intercalation Process in MXene Pseudocapacitors With Aqueous and Non-Aqueous Electrolytes

The 2D transition metal carbide and nitride MXenes, especially titanium carbide, are ideal electrode materials for pseudocapacitors due to their metallic conductivity, open interlayer space, and redox-active surface. This article summarizes the electrochemical ion intercalation processes in MXene-based pseudocapacitors with both aqueous and non-aqueous electrolytes. We discuss the impact of ion intercalation on the interfacial characteristics of MXenes, such as interlayer space, surface groups, and interfacial ion-solvent arrangement. Furthermore, we reveal the importance of ion accessibility on the overall pseudocapacitive performance of MXenes and summarize the general strategies to facilitate ion intercalation.