Abnormal contact electrification induced by mechanical deformation between identical materials

Contact electrification (CE) is known as the charge transfer between two surfaces upon contacting and separating, which has been exploited for the development of triboelectric nanogenerator (TENG). It is generally understood that CE is dependent on the difference of the charge affinity of dissimilar polymers, which is considered as an intrinsic property of polymers, i.e., CE is expected to be minor between identical materials. Here, abnormally evident CE behavior between identical polymers that are subjected to mechanical deformation (MD) to the plastic strain level is observed. Meanwhile, a unique correlation between the dynamic variation of coefficient of friction and friction electrification output is revealed as a result of the MD effect on CE. Analysis demonstrates that the observed MD effect on CE can be attributed to the strain-induced reconstruction of molecular structures of polymers. The present results indicate that CE/TENG is highly prone to the dynamic structure evolutions induced by contact-separation/friction, providing a new perspective to understand the intrinsic correlation between friction and CE behaviors between materials, as well as a potential way to modulate CE by MD.