The emergence of micropower-type applications such as self-powered sensors and miniaturized electronic systems has increased interest in on-chip electrochemical energy storage such as microsupercapacitors. Microsupercapacitors (MSCs) are high rate and high power yet miniaturized versions of macroscopic supercapacitors. MSCs with planar configuration have higher power density at potentially comparable energy density to thin-film batteries, while possessing essentially infinite cycle life. They could also offer compatible integration with smart electronic devices on an integrated chip (IC). In this dissertation, state-of-the-art microsupercapacitors based on Ti3C2Tx MXene and other pseudocapacitive electrode materials are proposed. The proposed strategies involve engineering both intrinsic properties of materials, fabrication methods and device architecture.