Fully printed, high energy density flexible zinc-air batteries based on solid polymer electrolytes and a hierarchical catalyst current collector

Abstract

Emerging applications such as flexible electronics and on-body medical devices have created an unmet need for a thin, high energy density, low cost, and low toxicity energy source. We propose here that metal air batteries are particularly attractive for these applications as they eliminate two of the thickness limiting components of other chemistries: the cation-storage cathode and thick encapsulation layers. For the first time, fully printed, ultrathin metal air batteries have been demonstrated with high areal capacities of ∼2 mAh cm−2 for total cell thicknesses, of <160 μm, including the substrate. This provides a volumetric capacity of >140 mAh cm−3 which is among the highest ever reported for cells approaching 100 μm in thickness. The printed cell stack utilizes a printable solid polymer electrolyte based on a non-volatile hydroxide anion ionic liquid and a printed porous hierarchically-structured catalyst layer. The catalyst layer is composed of a porous carbon nanotube cathode current collector network supporting a nanoscale MnCo2O4—decorated reduced graphene oxide air catalyst. This novel combination of materials enables a monolithic, fully printed, and continuous fabrication sequence for ultrathin batteries based on low toxicity materials that does not require an assembled mechanical separator structure or electrolyte filling steps.