Figures of Merit for Piezoelectrochemical Energy-Harvesting Systems

Mechanical micro-energy harvesting is a promising technology that could provide energy to small-scale sensors and other microelectronics without the need for traditional power sources. One such mechanism, called the piezoelectrochemical (PEC) effect, is of particular interest because many PEC systems have higher theoretical energy densities than other mechanical energy harvesters. This energy-harvesting mechanism has been demonstrated in multiple systems, including commonly used electrodes for lithium-ion batteries. However, due to the large variety of materials, it is difficult to consistently compare the utility of PEC systems, which makes the selection and optimization of PEC energy harvesters challenging. Here, we propose using figures of merit including short-circuit current (ΔISC), open-circuit voltage (ΔVOC),fill factor (FF), and efficiency (ηEC), which provide a unifying scheme to quantify the performance of different PEC systems. We experimentally validate this approach and demonstrate ways to increase voltage and current outputs of these harvesters.