Robust triboelectric-electromagnetic hybrid nanogenerator with maglev-enabled automatic mode transition for exploiting breeze energy

Exploiting the pervasive breeze energy is normally difficult due to the high start-up wind speed of the conventional electromagnetic generator (EMG) and the material abrasion of the emerging triboelectric nanogenerator (TENG). We report herein an automatic-mode-transition (AMT) strategy, which enables the TENG to work in intermittent-contact (IC) mode under a low wind speed of 2.4 m/s and automatically transition to noncontact (NC) mode with the increasing wind speed. Realized with a rationally designed maglev mechanism, the AMT-TENG can replenish the dissipated charges with very small friction drag and minute material abrasion, contributing to a low start-up speed, high mechanical durability, and enhanced electrical stability. During a 10-day durability test, the AMT-TENG can maintain 82 % of its incipient voltage; by contrast, the NC-TENG and C-TENG only retain 36 % and 10 % output voltage, respectively. The AMT-TENG can be upgraded easily to an AMT triboelectric-electromagnetic hybrid nanogenerator (AMT-TEHG) by simply adding pick-up coils, allowing the device to generate complementary electric outputs. By exploiting the breeze energy, the AMT-TEHG can serve not only as a self-sufficient wind speed sensor but also as a green energy source for some electronics. This work demonstrates a promising strategy for realizing robust TEHGs, which has great potential in breeze energy exploitation and self-sufficient sensing.