Heterointerface engineering and piezoelectric effect enhanced performance of self-charging supercapacitors power cell

Reasonable design of self-charging power cell (SCPC) is essentially significant to the development of wearable electronics devices owing to their ability to harvest/store energy in an integrated device. Herein, we propose a novel solid-state self-charging supercapacitor power cell (SCSPC) composed of NiCoP/NiCoN heterostructure as positive electrode and active carbon (AC) as negative electrode for energy storage and poly(vinylidene fluoride-co-trifluoroethylene)/barium titanate [P(VDF-TrFE)/BTO] piezo-film as separator to generate built-in piezoelectric field for energy harvesting. The homologous NiCoP/NiCoN heterostructure formed by in-situ phosphonitridation integrates the distinct advantages of optimized electronic structure and strong synergistic effect on heterointerface to realize efficient electron transport and fast reaction kinetics. The NiCoP/NiCoN heterostructure as self-supported electrode, achieves high capacitance of 3544 mF cm−2 (1772 F g−1) at the current density of 1 mA cm−2 and outstanding cycling stability. Benefiting from heterointerface engineering and piezoelectric effect, the SCSCP simultaneously exhibits excellent energy storage performance (a high energy density of 62.1 Wh kg−1 at 850 W kg−1) and superior self-charging characteristics (a self-charging voltage of 132 mV in 155 s). Our work provides a promising direction for the research of design and synthesis of heterointerface materials, as well as a new prospect for the development of the self-powered sustainable power sources.