Direct conversion of thermal energy to stored electrochemical energy via a self-charging pyroelectrochemical cell

Abstract

This work investigates a pyroelectrochemical cell (PEC) as a novel device concept for direct conversion of thermal energy to stored electrochemical energy. The PEC integrates a porous, pyroelectric separator within a supercapacitor. The pyroelectric separator induces an electric field within the PEC when exposed to a temperature change with time. The electric field drives ions into electrode double layers to charge the cell. Experimental results are coupled with simulations to explore PEC response when thermally cycled, with predicted pyroelectric orientation effects observed in two tests. When tested through amperometry, the pyroelectric separator showed a 155% increase in measured current upon heating compared to a 35% increase in measured current for a non-pyroactive separator. Under open circuit conditions, the PEC charged by 0.65 mV after four applications of a 20–30–20 °C thermal cycle. Finite element simulations confirm that the PEC self-charges by pyroelectric field-driven ion flux. With optimization of the pyroelectric separator, the PEC is predicted to generate >100 μJ cm⁻² of energy from temperature fluctuations commonly found in natural and built environments, making the PEC an exciting new energy source for low power Internet of Things sensors.