Strongly enhanced charge density via gradient nano-doping for high performance elastic-material-based triboelectric nanogenerators

Elastic-material-based triboelectric nanogenerators (EMB-TENGs) are most effective to harvest random (low frequency, low amplitude) and distributed mechanical energy. However, the low output of EMB-TENGs caused by drastic charge attenuation and low sensitivity limits its applications. Here, we propose a gradient nano-doping strategy to boost the charge density and sensitivity of triboelectric sponge materials via the gradient electrical field caused by the inhomogeneous concentration field of polytetrafluoroethylene nanoparticles. The triboelectric charge density (537 mu C.m(-3)) and the peak power density (732.6 mW.m(-3)) is increased by 1.2 times and 1.8 times. A sensitivity of 1.851 kPa(-1) is successfully realized at 50% compressive strain. From this, a self-powered smart boxing bag with functions of both the force analysis and real-time counting statistic was developed at the large strain. This work presents a new method for design and development of triboelectric materials, as well as expanding the functionalities and applications of self-powered system combining with the EMB-TENGs.