Inkjet-printed microband electrodes for a cost-efficient state-of-charge monitoring in redox flow batteries

A readily available prototyping process for the fabrication of low-cost microband electrodes is introduced, which are applicable for the accurate amperometric state-of-charge (SOC) measurement in redox flow battery (RFB) electrolytes. For this purpose, an inexpensive and straightforward inkjet printing of conductive platinum-based and insulating polymer-based inks was investigated. The overall inkjet-printed microband electrode performance in 0.4 M ferri-/ferrocyanide with 0.5 M KCl as supporting electrolyte were compared to sputter-coated microband electrodes and commercial disk microelectrodes using an SOC measurement method based on steady-state amperometry. Absolute root-mean-square deviations (RMSD) are below 1.04% SOC for the printed microband electrodes. The low material costs of about €2.52 (USD2.86) for the presented prototype and the simplicity of the fabrication process could facilitate a widespread application of the amperometric SOC measurement in RFBs.