Presenters: Paige Leland, College of Engineering, Chemical
Authors: Paige Leland, Katrina Le
Faculty Advisors: Rosanne Warren, College of Engineering, Mechanical
Institution: University of Utah
Due to the increasing use of remote, distributed sensing networks for environmental and human systems monitoring, efficient forms of electrical energy generation and storage are needed, leading to increased interest in small-scale, “self-powered” electrochemical cells. The incorporation of piezoelectric energy harvesting materials in electrochemical cells is a novel way to convert mechanical energy directly into stored electrochemical energy. However, much is still unknown about how to optimize the performance of these types of combined energy harvesting-storage cells, known as “self-charging power cells”. Self-charging power cells use porous polyvinylidene fluoride (PVDF) as a thin film separator for the electrochemical cell. PVDF is a piezoelectric material, meaning that the polarization of PVDF increases or decreases in response to mechanical stress. This changing polarization can drive ions through the separator, charging the electrochemical cell. In order to improve the efficiency of self-charging power cells, the piezoelectric performance and porous structure of PVDF films must be optimized. The goal of this research project is to study the effect of fabrication parameters on the piezoelectric response and battery performance of porous PVDF films. To fabricate a PVDF film, PVDF powder is dissolved in dimethylformamide solvent, mixed with barium titanate (BaTiO3) nanopowder that increases piezoelectric response, pulled with a doctor blade into a film, immersed in ethanol baths to produce varying porosities, and then annealed. The films are characterized via scanning electron microscopy, infrared spectroscopy, and materials testing to examine structure, electrical polarization, and electro-mechanical properties respectively. Together, these characterization techniques enable a comprehensive understanding of the effects of PVDF thin film fabrication parameters on the resulting piezoelectric properties and battery separator performance. This work is expected to result in an improved methodology to fabricate PVDF films that will result in better energy harvesting efficiency and higher quality piezoelectric separators for self-charging power cell applications.