A Decoupled Cycling Architecture of Asymmetric Zinc-Air Battery Unlocks Stable Catalyst Strategy and pH-Dynamic Influence

An asymmetric zinc–air battery (AZAB) employing membrane-separated acidic and alkaline electrolytes exhibits high output voltage and superior energy density. However, the bifunctional electrode suffers from severe catalyst degradation during cycling. Furthermore, the influence of pH dynamics on battery performance is challenging to investigate due to catalyst instability. The introduction of a pH gradient provides additional energy to the battery, but its impact on battery efficiency remains unexplored. Round-trip efficiency (RtE) is an effective indicator of battery efficiency. For fully enclosed batteries, RtE reflects the full capacity. While in half-open systems, RtE represents only partial capacity and is affected by pH dynamics. Therefore, a decoupled AZAB (DAZAB) featuring separated charge/discharge architectures is developed, which ensures catalyst stability and enables subsequent investigation of pH-dynamic influences. The contribution of the acid-base difference in the pH-decoupled system is described by a universal equation that defines a modified pH-dynamic RtE for standard comparison, making it suitable for half-open batteries operating on partial capacity. Moreover, an innovative, low-cost membrane and a carbon-based catalyst are fabricated for the battery. The well-designed DAZAB reveals the influence of pH dynamics on battery performance, offering an innovative pathway for efficient utilization of the acid-base gradient to achieve high battery efficiency.