The raised demand for portable electronics in high-temperature environments (>150 °C) stimulates the search for solutions to release the temperature constraints of power supply. All-solid-state microsupercapacitors (MSCs) are envisioned as promising on-chip power supply components, but at present, nearly none of them can work at temperature over 200 °C, mainly restricted by the electrolytes which possess either low thermal stability or incompatible fabrication process with on-chip integration. In this work, we have developed a novel process to fabricate highly thermally stable ionic liquid/ceramic composite electrolytes for on-chip integrated MSCs. Remarkably, the electrolytes enable MSCs with graphene-based electrodes to operate at temp...