High-efficiency self-charging power systems based on performance-enhanced hybrid nanogenerators and asymmetric supercapacitors for outdoor search and rescue

Self-charging power systems (SCPSs) that combine energy harvest/store technologies have attracted extensive attention owing to their vast potential in the Internet of things (IoT). Still, the long charging time is a severe obstacle to the practical use of SCPSs. Herein, we have successfully prepared a high-efficiency SCPS composed of a performance-enhanced rotational hybrid nanogenerator (R-HNG) and high-energy-density asymmetric supercapacitor (ASC). The R-HNG consists of a rotational triboelectric nanogenerator (R-TENG) and an electromagnetic generator (EMG), exhibiting superior charging performance. Among them, the output characteristics of the R-TENG can be enhanced by adjusting the work function difference between the friction layer and electrode. The working principle of the R-HNG is systematically explained by both Kelvin probe force microscope (KPFM) and finite element simulation. Meanwhile, the as-prepared ASC based on honeycomb-like NiCo-layered double hydroxides (LDH) nanosheets are used as an energy storing device within SCPS. The SCPS can reach 5.9 V after 120 s under a rotation speed of 200 rpm, which can power a homemade positioning device for outdoor search and rescue. This work provides a novel and effective solution for constructing high-performance SCPSs and is expected to accelerate the development of SCPSs in the IoT.