Flexible micro-supercapacitors (MSCs) based on 2D MXenes offer strong potential for next-generation energy storage in wearable and integrated electronics, yet still face critical challenges such as limited energy density, mechanical reliability, and scalable large-area manufacturing. This review surveys recent strategies to address these limitations, with a particular focus on fabrication techniques and wafer-level integration approaches. Wafer-scale processing on both rigid and flexible substrates has emerged as a key milestone toward scalable, high-yield industrial production of flexible MSCs. By examining the strengths and drawbacks of current fabrication strategies, this review highlights essential directions for advancing MXene-based flexible MSCs toward practical and widespread application.

Nitrogen-doped graphene was synthesized by a hydrothermal method using graphene oxide (GO) as the raw material, urea as the reducing agent and nitrogen as the dopant. The morphology, structure, composition and electrochemical properties of the samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorptiondesorption analysis, electrical conductivity and electrochemical tests. The results show that urea can effectively reduce GO and achieve nitrogen doping under the hydrothermal conditions. By adjusting the mass ratio of raw materials to dopants, the graphene with different nitrogen doping contents can be obtained; the nitrogen content range is from 5.28~6.08% (atomic fraction percentage).When the ratio of dopant to urea is 1:30, the nitrogen doping content reaches a maximum of 6.08%.The supercapacitor performance test shows that the nitrogen content prepared by the ratio of 6.08% is the best at 0.1 A·g^-1. The specific capacitance is 95.2 F·g^-1.

Flexible fiber- or yarn-based one-dimensional (1-D) energy storage devices are essential for developing wearable electronics and have thus attracted considerable attention in various fields including ubiquitous healthcare (U-healthcare) systems and textile platforms. 1-D supercapacitors (SCs), in particular, are recognized as one of the most promising candidates to power wearable electronics due to their unique energy storage and high adaptability for the human body. They can be woven into textiles or effectively designed into diverse architectures for practical use in day-to-day life. This review summarizes recent important development and advances in fiber-based supercapacitors, concerning the active materials, fiber configuration, and applications. Active materials intended to enhance energy storage capability including carbon nanomaterials, metal oxides, and conductive polymers, are first discussed. With their loading methods for fiber electrodes, a summary of the four main types of fiber SCs (e.g., coil, supercoil, buckle, and hybrid structures) is then provided, followed by demonstrations of some practical applications including wearability and power supplies. Finally, the current challenges and perspectives in this field are made for future works.

A hybrid supercapacitor is a promising energy storage device in view of its excellent capacitive performance. Commercial three-dimensional foam nickel (Ni) can be used as an ideal framework due to an interconnected network structure. However, its application as an electrode material for supercapacitors is limited due to its low specific capacity. Herein, we report a successful growth of MnO₂ on the surface of graphene by a one-step hydrothermal method; thus, forming a three-dimensional MnO₂-graphene-Ni hybrid foam. Our results show that the mixed structure of MnO₂ with nanoflowers and nanorods grown on the graphene/Ni foam as a hybrid electrode delivers the maximum specific capacitance of 193 F·g^-1 at a current density 0.1 A·g^-1. More importantly, the hybrid electrode retains 104% of its initial capacitance after 1,000 charge-discharge cycles at 1 A·g^-1; thus, showing the potential application as a stable supercapacitor electrode.