High‐Performance and Flexible Co‐Planar Integrated Microsystem of Carbon‐Based All‐Solid‐State Micro‐Supercapacitor and Real‐Time Temperature Sensor

With the rapid development of flexible and portable microelectronics, the extreme demand for miniaturized, mechanically flexible, and integrated microsystems are strongly stimulated. Here, biomass‐derived carbons (BDCs) are prepared by KOH activation using Qamgur precursor, exhibiting three‐dimensional (3D) hierarchical porous structure. Benefiting from unobstructed 3D hierarchical porous structure, BDCs provide an excellent specific capacitance of 433 F g −1 and prominent cyclability without capacitance degradation after 50 000 cycles at 50 A g −1 . Furthermore, BDC‐based planar micro‐supercapacitors (MSCs) without metal collector, prepared by mask‐assisted coating, exhibit outstanding areal‐specific capacitance of 84 mF cm −2 and areal energy density of 10.6 μWh cm −2 , exceeding most of the previous carbon‐based MSCs. Impressively, the MSCs disclose extraordinary flexibility with capacitance retention of almost 100% under extreme bending state. More importantly, a flexible planar integrated system composed of the MSC and temperature sensor is assembled to efficiently monitor the temperature variation, providing a feasible route for flexible MSC‐based functional micro‐devices.