Simulation of a Nickel-Zinc Battery on the Cell Level

Kurzfassung

The growing demand for electric energy in combination with a progressing incorporation of renewable energy sources into the power grid calls for sustainable energy storage. The nickel-zinc battery technology, amongst others, is a promising candidate for this task due to abundant and low-cost resources, environmentally friendly and recyclable materials and non-flammable components in connection with competitive specific power and energy [1,2]. Besides these desirable characteristics, limited understanding of the phenomena in nickel-zinc cells prevent the design of a battery with high cycle life. Relevant challenges are the zinc conversion at the negative electrode, proton intercalation at the NiOOH/Ni(OH)2 electrode and gas formation consuming electrolyte, which leads to a dry-out of the cell. Consequentially, these are processes which influence the performance of the cell and induce its degradation. To study such a nickel-zinc cell during cycling, a physics-based and volume-averaged 3D+1D model is implemented, which was derived from existing models [3]. The thermodynamic framework used comprises transport processes and electrochemical reactions. The volume-averaged 3D approach allows to examine the distribution of chemical species and phases (Fig. 1) during cycling on a cell level [4]. Based on realistic battery parameters, geometry and composition, the evolution of concentration fields and shape change of the zinc electrode are investigated during charge and discharge operations.