On May 10, 2022, Advanced Materials are presented under the title "Energy Conversion Analysis of Multi-Layered Triboelectric Nanogenerators for Synergistic Rain and Rain Solar Energy Harvesting "reports on the work of the Instantaneous Friction Nanogenerator (I-TENG) developed by the team of Xiaofeng Xu and Xiaoyi Li at Ocean University of China, which consists of a bionic surface structure and an instantaneous switch structure design.

Researchers developed transient friction nano generator (I-TENG) on Pt line as the top electrode, indium tin oxide/silver nanowires (from feng first nano) composite electrode as the bottom electrode, polytetrafluoroethylene (PTFE) as friction layer, and on the surface of PTFE by plasma etching with micro/nano columnar bump bionic structure. These biomimetic structures give the device superhydrophobic properties, which can increase the surface charge density and reduce liquid residue at the interface. The voltage, current, transfer charge and energy conversion efficiency of I-TENG are 150 V, 1.25 mA, 150 nC and 24.89%, respectively, which are much higher than previously reported.

In addition, a quantitative method called Kinetic energy Calculation and Current Integration Method (KECCI) is proposed to characterize the energy conversion flow, droplet falling velocity, input mechanical energy/kinetic energy, and frictional pressure. Based on this method, the effective pressure on the friction surface and the optimal drop height on the surface can be obtained to facilitate the understanding of the energy flow in the TENG system and guide the development of multi-layer structural design for such systems.

The multi-layer I-TENG designed by the team can collect the energy of raindrops for several consecutive times, significantly improving the energy conversion efficiency. A hybrid energy harvesting system consisting of a high-performance I-TENG and PSC can alternately capture rainwater and solar energy. This study is a milestone in establishing a quantitative analysis of the energy conversion process of TENG and a comprehensive understanding of its working principle. In addition, it provides strategies for the design and manufacture of efficient devices, thus accelerating the commercialization process of the TENG.

The silver nanowires used in this paper come from XFNANO.

Literature link:https://doi.org/10.1002/adma.202202238