Zinc based metal-air batteries have the advantage of high energy density, because oxygen from ambient air is used without in-cell storage. As a consequence, lighter batteries are produced with the reversible available Zinc as the only limiting factor.

However, before Zn-air batteries can be used as secondary elements some obstacles have to be overcome. The low cyclability of state of the art Zn-air batteries is caused by the passivation rate and dendrite growth of zinc, carbonate formation in the alkaline electrolytes, corrosion of cathode materials and flooding of the cathode.

Due to the volume expansion of Zinc in alkaline Zn-air batteries, it is important to optimize the penetration depth of electrolyte into the porous structure of the cathode by an appropriate pore size distribution.

Electrochemical impedance spectroscopy measurements were conducted for different applied electrolyte pressures and correlated to the electrolyte penetration depth and the electrochemical performance.

To get a better understanding how the electrolyte infiltrates the porous structure, an electrolyte intrusion cell was build. The volume increase and decrease of the zinc during charge and discharge could be mimicked with the developed cell by electrolyte intrusion and extrusion. The effect of the pore size distribution is strongly reflected in this measurements. This test was done for electrodes at different stages of degradation, to see how the penetration characteristics change over the cycle life of the cathode and how a long life battery could be obtained. Additionally electrodes at different state of charge (SOC) were compared and, in addition, changes in hydrophilic and hydrophobic pore properties were studied.