Dispenser Printed Electrochemical Capacitors for Power Management of Millimeter Scale Lithium Ion Polymer Microbatteries for Wireless Sensors

A direct write dispenser printing system demonstrates a flexible method for integrating electrochemical energy storage components onto an autonomous device. The capacitor’s function will be to extend the lifetime of a rechargeable battery by absorbing the high power demands of the electronic device. Electrochemical capacitors based on mesocarbon microbeads suspended in a poly(vinylidene fluoride) polymer binder are printed onto a substrate. The electrolyte is composed of the binder and 1-butyl-3-methylimidazolium tetrafluoroborate, a room temperature ionic liquid. The electrode and electrolyte films are printed successively on top of each other. The gel electrolyte flows and therefore can be printed, but when dried, has enough mechanical strength to support the weight of the top electrode and current collector. It also has a high room temperature ionic conductivity of 10 Scm, sufficient for high power devices, like wireless sensors. Cyclic voltammetry of the electrolyte showed its electrochemical stability with respect to potential. The capacitors were also galvanostatically cycled and a discharge capacity of 65+7.5μF was calculated.