Expecting the unexpected: high pressure crystallization significantly boosts up triboelectric outputs of microbial polyesters

Abstract

Bio-triboelectric nanogenerators (bio-TENGs) have become one of the choices of energy supply for new electronic devices, but the relationship between the internal crystalline structure of bio-derived materials and the triboelectric performance has not been investigated. In this paper, microbial polyhydroxybutyrate (PHB) with special wrinkled spherulites is prepared by a high-pressure solid-state forming method, which unexpectedly facilitates the contact electrification of PHB. When the PHB-based TENG is stimulated, the intrinsic micro-/nanoscale dual crystalline structure of wrinkled spherulites enables significant improvement of the surface charge density of PHB. The open-circuit voltage and short-circuit current of the high-pressure crystallized PHB based TENG are around 5 and 12 times higher than those of the normal-pressure crystallized PHB-based TENG, respectively. Moreover, the bio-TENG shows remarkable stability and durability, and can be utilized as a reliable power source to drive commercial LEDs. In particular, the self-powered TENG sensor based on high-pressure crystallized PHB exhibits great prospects for monitoring and recognizing human athletic motions. This work shows that there is a simple but novel method to improve the performance of bio-TENGs, which not only determines the relationship between the crystalline structure of biomaterials and triboelectricity, but also provides a new insight for developing high-performance and environment-friendly electronic devices.