Recent Progress in MXene-Based Electrochemical Actuators and Capacitors

A new family of two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXenes) has attracted increasing attention owing to their electrical, chemical, and physical properties. Together with various attractive properties of the MXenes, they also exhibit electrochemical induced deformation (i.e., expansion/contraction) via ion intercalation/de-intercalation in/from MXene layers. In this respect, MXenes offer the possibility of application as the electrode of electrochemical actuators (ECAs). While the MXene-based ECAs are still in their infancy stage, researchers have made great effort to achieve high-performance MXene-based electrochemical capacitors (ECs). As the name suggests, both ECAs and ECs shared common traits in which their operations are based on electrochemical processes. This review provides the recent progress in the MXene-based ECAs in parallel with that in the MXene-based ECs to gain insights from the relatively mature developments in EC applications. Finally, based on the findings from previous studies on both electrochemical applications, perspectives on future MXene-based ECAs in terms of electrode, electrolyte, and cell configuration are provided.