(148f) Novel Wave-Shaped MnO2 Cathode Supported by a Partially Porous Nickel Layer for Fuel Cell/Battery

Increasing global demand for green energy has boosted the development of various means of energy generation and storage. Both fuel cells and batteries show big potential for an increasing amount of applications, however they still suffer from various drawbacks. Among others, fuel cells possess a low power density, which can mainly be ascribed to the reaction that occurs at a three-phase interface between electrode, electrolyte and cathodic and anodic reactants. Batteries, on the other, hand lack high energy density, whose reason lies in the limited amount of active material in the electrodes.

To eliminate each one’s drawback, a so called Fuel Cell/Battery (FCB) has been suggested in previous works. As the name implies, it can work both as a fuel cell and battery. When working as latter, the best results were obtained when coating MnO₂ via electrochemical deposition on carbon fibers. However, oxygen charging – crucial when running in fuel cell mode – was fairly poor. Therefore, a novel cathode structure is presented in this work.

On the one hand, a high surface area to enhance the oxygen charging rate is obtained via a wave-shaped structure in the micrometer scale. Thanks to the obtained surface increase, a reaction rate improvement by up to one order of magnitude is expected compared to a flat electrode. To tackle the problem of having to charge electrically insulating MnO₂ via oxygen while enabling electron collection, a novel, tunnel-looking structure has been developed. Via template method, a several micrometer thick Nickel electrode with one micrometer long pillars has been obtained through electrochemical deposition. On top of the pillars, MnO₂ is deposited, creating a triple layer consisting of MnO₂, porous Nickel, and bulk Nickel.