Characteristics of Sodium‐Ion Capacitor Devices

In this chapter, the classical features of SICs are summarized. In addition, some important parameters in SICs are reflected by a simple example and a rational construction. Another way of classifying SICs is explained by discussing the criterion of whether the electrolyte is consumed or not, namely the electrolyte consumption mechanism and the sodium ion transport mechanism. This is followed by a presentation of equations to provide further insight into SICs, which further show the similarities and differences between capacitive and battery-type materials. The differences between non-Faraday materials, pseudocapacitive Faraday materials, and Faraday battery-type materials are briefly discussed. Finally, the future trends of multivalent hybrid ion capacitors based on device characteristics and the mechanism of SEIs in SICs are briefly discussed.