Separation-Free Planar Interconnection for Thermo-electrochemical cells

A thermo-electrochemical cell (TEC) that converts low-grade waste thermal energy into electricity shows great sustainability for powering emerging wearable devices and Internet of Things (IoT) sensors. To meet any voltage requirement for practical applications, two types of interconnection methods, such as banded and flip-flop interconnections, have been widely used to integrate TECs in electrical series. However, these methods involve injecting an electrolyte into each cell one at a time and reliably sealing the cells, which becomes challenging when connecting a large numbers of TECs. To address this issue, we propose a separation-free planar series interconnection (SPSI) configuration that allows TECs to be electrically connected in series using a single electrolyte injection and sealing process, resulting in a simple TEC integration method. An electrochemical equivalent circuit for the SPSI configuration is investigated to determine design parameters affecting the output voltage and power from the TECs. As a practical demonstration, a strip-shaped TEC device consisting of 25 cells is fabricated and wrapped around a heat pipe to convert the temperature difference between the surface of a heat pipe and its surroundings into electricity. The introduction of this interconnection method would induce significant advances in TEC integration and application.