PAN/MXene: a potent piezo-gen and cogent piezoelectric separator for self-chargeable supercapacitors.

All-in-one self-charging devices with integrated storage systems have become one of the bottlenecks of research at present. Amidst a worthwhile contribution to this direction of research, we present a self-charging piezo-supercapacitor device (SCPS) consisting of carbonized polyacrylonitrile/MXene (C-PMX) nanofiber electrodes, a PMX nanofiber separator, and PVA/KOH as a gel electrolyte. First, the energy harvesting properties of PMX, followed by self-charging energy storage, were studied discretely. The piezoelectric nanogenerator (PNG) with PMX-3% showed the highest output voltage, short-circuit current, and power density of 9.9 V, 1124 nA, and 9.6 μW cm^-2, respectively. Consequently, the SCPS offered a device-specific capacitance of 100.5 F g^-1, along with an energy density of 5 Wh kg^-1 at a power density of 300 W kg^-1 and 92% capacitance retention. Further evaluation of self-charging was carried out with compression and tapping. Interestingly, the SCPS-CF can be charged up to 250 μV in just 0.2 s, while the discharge time takes about 1.5 s. Moreover, the influence of piezo-separators in piezo-electrochemical conversion and rectifications with SCPS-NF is discussed in detail. Thus, a new insight into the integration of harvesting and storage for future self-powered electronics has been brought in.