Schottky model for triboelectric temperature dependence

Abstract

The triboelectric effect, charging by contact, is the working principle in a device called a triboelectric nanogenerator. They are used as efficient energy transducers in energy harvesting. In such generators the charging of surfaces at contact is followed by a separation of the surfaces increasing the electrical energy which can subsequently be used. Different materials have different triboelectric potentials leading to charging at contact. The temperature dependence of the charging has just recently been studied: the triboelectric effect is decreasing with temperature for a generator of Al-PTFE-Cu. Here, we suggest a mechanism to explain this effect assuming ion transfer using a two-level Schottky model where the two levels corresponds to the two surfaces. The difference in binding energy for ions on the two surfaces then enters the formula for charging. We fit the triboelectric power density as a function of temperature obtained from a two-level Schottky model to measured data for nanogenerators made of Al-PTFE-Cu found in three references. We obtain an average separation energy corresponding to a temperature of 365 K which is of the right magnitude for physically adsorbed atoms. We anticipate that this model could be used for many types of triboelectric nanogenerators.

Microphysical Effects of Water Content and Temperature on the Triboelectrification of Volcanic Ash on Long Time Scales

“…We also observe that charging of the volcanic sample decreases as the temperature increases. As discussed above, similar behaviors have been noted in nonvolcanic materials by a number of investigators (e.g., Greason, 2000;Lu et al, 2017;Olsen et al, 2018;and Su et al, 2015).…”

“…For example, Greason [2000] found that the magnitude of charge on beads in a vibrated bed decreases with increasing temperature. Additionally, Olsen et al [2018] notes that some researchers (including Wen et al [2014], Su et al [2015], and Lu et al [2017]) report a power output decrease with temperature in triboelectric nano-generators. Temperature variations may also affect the presence of contaminants on surfaces, changing their ability to gain or retain charge [Lowell and Rose-Innes, 1980].…”

Microphysical effects of water content and temperature on the triboelectrification of volcanic ash on long timescales

“…and Olsen et al [2018]). Note that the effect of changing humidity is greater than that of changing temperature.…”

Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator

“…Triboelectric nanogenerators (TENG:s) are used as efficient energy transducers in energy harvesting to replace the need for batteries for small electronic devices 1–4 , or as sensors for different physical properties. For many types of generators containing non-metals the triboelectric charging seems to be done by ion transfer 5,6 or by electron transfer between potential wells of atoms 7 or by both mechanisms. At separation of the surfaces of the generator the so created charge differences induce an electric voltage that contains energy to be harvested.…”