OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available online. The article discusses the development of ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon (OLC). These supercapacitors have high power density, capacitance, and energy density, with discharge rates up to 200 V s⁻¹, which is three orders of magnitude higher than conventional supercapacitors. The microsupercapacitors are produced by electrophoretic deposition of a several-micrometre-thick layer of nanostructured OLC. The high surface-to-volume ratio of the active material allows for efficient ion access, enhancing performance. The study compares the performance of OLC-based microsupercapacitors with other energy storage devices, showing that OLC-based microsupercapacitors have a much higher energy density and power density than electrolytic capacitors and batteries. The research highlights the potential of OLC for high-power, high-energy storage applications in microelectronics, wireless sensor networks, and biomedical devices. The study also discusses the advantages of OLC over other carbon materials, including its fully accessible surface area and binder-free deposition technique. The results demonstrate that OLC-based microsupercapacitors can compete with batteries and conventional electrolytic capacitors in various applications. The study is supported by references to previous research on electrochemical capacitors, supercapacitors, and energy storage materials.OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available online. The article discusses the development of ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon (OLC). These supercapacitors have high power density, capacitance, and energy density, with discharge rates up to 200 V s⁻¹, which is three orders of magnitude higher than conventional supercapacitors. The microsupercapacitors are produced by electrophoretic deposition of a several-micrometre-thick layer of nanostructured OLC. The high surface-to-volume ratio of the active material allows for efficient ion access, enhancing performance. The study compares the performance of OLC-based microsupercapacitors with other energy storage devices, showing that OLC-based microsupercapacitors have a much higher energy density and power density than electrolytic capacitors and batteries. The research highlights the potential of OLC for high-power, high-energy storage applications in microelectronics, wireless sensor networks, and biomedical devices. The study also discusses the advantages of OLC over other carbon materials, including its fully accessible surface area and binder-free deposition technique. The results demonstrate that OLC-based microsupercapacitors can compete with batteries and conventional electrolytic capacitors in various applications. The study is supported by references to previous research on electrochemical capacitors, supercapacitors, and energy storage materials.