Crystallization-Induced Shift in a Triboelectric Series and Even Polarity Reversal for Elastic Triboelectric Materials.

A stretchable triboelectric nanogenerator (TENG) can be a promising solution for the power supply of various flexible electronics. However, the detailed electrification mechanism of elastic triboelectric materials still needs to be clarified. In this work, we found crystallization behavior induced by strain and low temperature can lead to a shift in a triboelectric series for commonly used triboelectric elastomers and even reverse the triboelectric polarity. This effect is attributed to the notable rearrangement of surface electron cloud density happening along with the crystallization process of the molecular chain. This effect is significant with natural rubber, and silicone rubber can experience this effect at low temperature, which also leads to a shift in a triboelectric series, and an applied strain at low temperature can further enhance this shift. This study demonstrated that the electrification polarity of triboelectric materials should be re-evaluated under different strains and different temperatures, which provides a mechanism distinct from the general understanding of elastic triboelectric materials.