As one of the most important micro energy storage devices (MESDs), graphene-based micro-supercapacitors (G-MSCs) possess the advantages of excellent flexibility, long cycle life, affordability and high reliability. In most cases, constructing three-dimensional (3D) graphene networks is widely utilized to promote the permeation of electrolyte and enhance the utilization of active materials. In this work, conventional freeze-drying process is utilized in the fabrication of G-MSCs to constitute 3D interconnected networks micro-electrodes, and further by regulating the composition of inks, carbon spheres (CSs) at different mass loadings are introduced into the graphene scaffolds to further increase the active sites of the micro-electrodes. The fabricated all carbon-based MSC with the optimal mass loading of CSs (0.406 mg cm⁻²) exhibits a high specific areal capacitance of 17.01 mF cm⁻² at the scan rate of 10 mV s⁻¹ and a capacitance retention of 93.14% after 10000 cycles at the scan rate of 500 mV s⁻¹. The proposed microfabrication process is facile and fully compatible with modern microtechnologies and will be highly suitable for large-scale production and integration.

A novel microfabrication process based on optimized photolithography combined with pyrolysis-reduction is proposed to fabricate interdigital porous carbon/tin quantum dots (C/Sn QDs) microelectrodes. C/Sn QDs active microelectrodes are also employed as current collectors of a micro-supercapacitor (MSC). A uniform dispersion of Sn QDs (diameter of ~3 nm) in the carbon matrix is achieved using our facile and controllable microfabrication process. The as-fabricated C/Sn QDs MSC obtained by carbonization at 900 ℃ exhibits a higher areal specific capacitance (5.79 mF·cm^-2) than that of the pyrolyzed carbon-based MSC (1.67 mF·cm^-2) and desirable cycling stability (93.3% capacitance retention after 5, 000 cyclic voltammetry cycles). This novel microfabrication process is fully compatible with micromachining technologies, showing great potential for large-scale fine micropatterning of carbon-based composites for applications in micro/nano devices.

In the last decade, pyrolyzed-carbon-based composites have attracted much attention for their applications in micro-supercapacitors. Although various methods have been investigated to improve the performance of pyrolyzed carbons, such as conductivity, energy storage density and cycling performance, effective methods for the integration and mass-production of pyrolyzed-carbon-based composites on a large scale are lacking. Here, we report the development of an optimized photolithographic technique for the fine micropatterning of photoresist/chitosan-coated carbon nanotube (CHIT-CNT) composite. After subsequent pyrolysis, the fabricated carbon/CHIT-CNT microelectrode-based micro-supercapacitor has a high capacitance (6.09 mF·cm^–2) and energy density (4.5 mWh·cm^–3) at a scan rate of 10 mV·s^–1. Additionally, the micro-supercapacitor has a remarkable long-term cyclability, with 99.9% capacitance retention after 10, 000 cyclic voltammetry cycles. This design and microfabrication process allow the application of carbon microelectromechanical system (C-MEMS)-based micro-supercapacitors due to their high potential for enhancing the mechanical and electrochemical performance of micro-supercapacitors.