Fabrication and inkjet printing of manganese oxide electrodes for energy storage

Inkjet printing of nanoparticle inks is rising method for fabricating energy storage electrodes and is driven by the demand for supercapacitors and flexible batteries for wearables. The process can be optimized on two fronts, the printing parameters and the ink fabrication. Researchers often lack control over ink formulation and must instead focus on optimizing printing parameters. This study demonstrates that both aspects can be optimized using Pulsed Laser Ablation in Liquid (PLAL) to tailor nanoparticle ink properties, coupled with real-time process monitoring and design of experiments for inkjet printing. Automated in-line monitoring of nanoparticle size and concentration via UV–Vis and DLS measurements every 5 min provided real-time data. The final ink had a mean particle size of 3 nm with a viscosity of 1.3 mPa.s. A design of experiments approach examined the effects of inkjet parameters on print quality on a polymer substrate with optimal printing conditions found to be 30 layers, 40 kHz jetting frequency, and 28 °C nozzle/bed temperature based on consistency in pixel values. The resulting Mn electrodes exhibited pseudocapacitive behavior with initial oxidation leading to stable manganese oxides. XPS analysis of printed electrodes revealed a chemical composition of MnO (64 %), MnO₂ (26 %), and Mn₂O₃ (9 %).