Recent Advances of the Electrode Materials for Sodium-Ion Capacitors

Sodium ion hybrid capacitors (SIHCs) have been considered to be one of the most promising electrochemical energy storage devices because of the abundant and low cost of sodium resources , and their similar physical and chemical properties to that of the lithium. SIHCs are usually assembled with high-energy anode and high-power cathode , which can bridge the energy and power gaps between sodium-ion batteries and supercapacitors. However, their large-scale application is strongly impeded by the kinetics and capacity imbalance between capacitive-type cathode and battery-type anode. In this paper, the working principle of SIHCs and the research progress of various anode and cathode materials are summarized. The development trend of SIHCs is reviewed emphatically from the aspects of controlled preparation and modification of material structure. The main challenges encountered in the development of SIHCs are discussed and the future research direction of the electrode materials in this field is prospected.