Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat-to-electricity conversion efficiency hinder further application. In this paper, we designed a high-performance thermally chargeable supercapacitor device composed of ZnMn₂O₄@Ti₃C₂T_x MXene composites (ZMO@Ti₃C₂T_x MXene) electrode and UIO-66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro-propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K⁻¹, thermal voltage of 243 mV, and outstanding heat-to-electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge–discharge cycling stability at high-temperature differences (3 K) and low-temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.

On-chip microsupercapacitors (MSCs) compatible with on-chip geometries of integrated circuits can be used either as a separate power supply in microelectronic devices or as an energy storage or energy receptor accessory unit. In this work, we report the fabrication of flexible two-dimensional Ni(OH)₂ nanoplates-based MSCs, which achieved a specific capacitance of 8.80 F/cm³ at the scan rates of 100 mV/s, losing only 0.20% of its original value after 10, 000 charge/discharge cycles. Besides, the MSCs reached an energy density of 0.59 mWh/cm³ and a power density up to 1.80 W/cm³, which is comparable to traditional carbon-based devices. The flexible MSCs exhibited good electrochemical stability when subjected to bending at various conditions, illustrating the promising application as electrodes for wearable energy storage.