Recent advances in micro-supercapacitors for AC line-filtering performance: From fundamental models to emerging applications

Recently, micro-supercapacitors (MSCs) have undergone major development as next-generation micro-electrochemical energy storage devices for self-powered, integrated, and wearable systems, thanks to their excellent performance capability. In particular, their rapid frequency response characteristics make them potential candidates to replace conventional capacitors and function as alternating current (AC) line filters to rectify pulse energy or as current ripple filters in the kHz range. However, few papers have been published about the associated fundamental device components, architectures, and correct characterization of MSCs applied in filter applications. In addition, it is a huge challenge to achieve a balance between capacitance and frequency response, not yet to be overcome. This review comprehensively summarizes recent advances in MSCs for AC line-filtering, from fundamental mechanisms to appropriate characterization and emerging applications. Special attention is given to progress in microfabrication strategies, electrode materials, and electrolytes for high-frequency MSCs. We also present perspectives and insights into the development of MSCs in different frequency ranges for AC line-filtering applications.