Sodium symphony: Crafting the future of energy storage with sodium-ion capacitors

The high-power density enables rapid charging of energy storage devices. As technology advances, this is increasingly becoming a crucial method to evaluate these systems. Ionic hybrid capacitors are designed to provide more strength and higher energy storage capacity compared to electric double-layer capacitors. By fusing the best features of ionic batteries with electric double-layer capacitors, ionic hybrid capacitors expect to outperform both in terms of energy density as well as power density. Substituting lithium-ion capacitors with sodium-ion capacitors offers cost and material savings, among other advantages. The metal oxide electrodes possess a greater potential specific capacity compared to carbon-based electrodes due to their robust redox reaction. Therefore, they exhibit excellent compatibility with solid-state batteries, commonly referred to as sodium-ion capacitors. In the case of electric double-layer capacitors, the power output gap is reduced due to the high surface pseudocapacitance properties of metal oxide electrodes, which facilitate rapid ion movement. Metal oxides resolved the incompatibility between sodium-ion capacitor electrodes and electric double-layer capacitor counter electrodes. These issues were compounded by the reported drawbacks of metal oxides, such as poor electrical conductivity and significant expansion. To produce high-performance silicon carbides, it is crucial to adhere to appropriate modification techniques and electrode compatibility criteria. This item provides a concise summary of the study conducted on solid-state capacitor electrodes composed of various metal oxides, including the materials utilized. Additionally, there is a comprehensive discussion of the storage mechanism and construction of sodium-ion capacitors. Ultimately, this study provides an extensive understanding and more insights into enhancing the concert of metal oxide electrodes as well as exploring their potential applications, hence promoting further investigation in this field.