Liquid‐Locked Bassanites for Scalable Fabrication of High‐Temperature Micro‐Supercapacitors Working at 300 °C

Abstract Many emerging industry applications demand electronic systems with reliable operation at temperatures >300 °C. To date, the most promising on‐chip power sources, micro‐supercapacitors (MSCs), can only operate at temperatures up to 250 °C for a short period as limited by the vulnerability of their electrolyte frameworks at high temperatures. Here, a strategy is proposed to use liquids to lock the phase transformations of bassanite microrods for scalable on‐chip printing of interlocking ceramic frameworks with high thermal stability. The robust ceramic frameworks enable simple yet scalable fabrication of MSCs to work at 300 °C with an areal capacitance of up to >60 mF cm ⁻² and only ≈3% performance degradation after 1000 cycles during a test period of ≈3 h. A large‐scale MSC array, consisting of 20 cells within a footprint area of 4 cm × 8 cm, has been able to supply a power of 7.2 mW at 300 °C. These break through the present limit of 250 °C of almost all high‐temperature energy storage devices and pave the way for on‐chip MSCs for high‐temperature electronics.