Abstract
Usually, high temperature decreases the output performance of triboelectric nanogenerator because of the dissipation of triboelectric charges through the thermionic emission. Here, a temperature difference triboelectric nanogenerator is designed and fabricated to enhance the electrical output performance in high temperature environment. As the hotter friction layer’s temperature of nanogenerator is 0 K to 145 K higher than the cooler part’s temperature, the output voltage, current, surface charge density and output power are increased 2.7, 2.2, 3.0 and 2.9 times, respectively (from 315 V, 9.1 μA, 19.6 μC m−2, 69 μW to 858 V, 20 μA, 58.8 μC m−2, 206.7 μW). With the further increase of temperature difference from 145 K to 219 K, the surface charge density and output performance gradually decrease. At the optimal temperature difference (145 K), the largest output current density is 443 μA cm−2, which is 26.6% larger than the reported record value (350 μA cm−2).
Highlights
High temperature decreases the output performance of triboelectric nanogenerator because of the dissipation of triboelectric charges through the thermionic emission
The electron thermionic emission in triboelectric nanogenerators (TENG) has been studied[22–24], which is used to explain the influence of temperature on the output performance of TENG
This work is done in nanoscale by using an atomic force microscope (AFM) tip, it gives a possibility in principle that the temperature difference between two friction layers can be utilized to enhance the output of TENG through rational design
Summary
Theoretical study of the influence of ΔT on TENG’s output. Taking the heat exchanges between hotter and cooler friction layers into account, the temperature of the cooler friction layer will continuously rise through the air and contacting heat transfer, and the accumulated charges in the cooler friction layer will gradually escape to the air as well as the hotter friction layer by electron thermionic emission. Because of the electron thermionic emission effect of triboelectric charges, as the right part of Fig. 1a shows, electrons are easier to escape out of the potential well and get back to the hotter friction layer in contact processes or spill into the air when the temperature of the cooler friction layer increases, which reduces charge density and output performance of TENG. Λ1 A0 k qv TcekTc , where λ1 is the material-specific correction factor, A0 is Richardson constant of a free electron, k is the Boltzmann constant, the relationship between surface charge density of TENG and temperature difference ΔT (ΔT=Th-Tc) is calculated (Fig. 1b). E, when the thermal conductivity of the cooler friction layer increases from 0.06 W m−1 K−1 to 0.18 W m−1 K−1, the effect of Th on Tc gradually decreases (Supplementary Fig. 2), and the material-related correction factor a change from 0.224 to 0.101. Through the classical electrodynamics derivation and by ignoring the effect of borders, the relationship between the voltage output of TDNG (V(t)) and ΔT can be established as follows
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