Alkaline zinc-air batteries (ZABs) have gained interest in recent years for their high theoretical energy density as well as their use of low-cost abundant zinc metal for the anode. In order to overcome activation energy barrier of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), commonly noble metals are used. Within this work, transition metal-functionalized Poly(heptazine imide)s (PHIs) are studied as an alternative and more abundant electrocatalyst as they offer the homogenous immobilization of metals within their ordered structure. Introducing Fe and Ni into the PHI network enables the formation of single and mixed transition metal PHIs, that show reduced overpotentials for ORR and OER. The formation of Ni single atoms even induces outstanding catalytic activity for the OER during charging of ZAB full cells with performance comparable to that of RuO₂. Furthermore, full cell tests show excellent stability over the course of 250 discharge-charge cycles, making it a promising system for sustainable energy storage. This work paves the way for the molecular design of a novel material class as electrocatalyst for ZAB.
Jacobi et al. (Thu,) studied this question.