Reversible Cobalt‐Species Transformation During Charge–Discharge Cycling to Improve Zinc‐Air Battery Stability

ABSTRACT Efficient bifunctional catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), together with real‐time mechanistic insight, are critical to advancing high‐performance zinc–air batteries (ZABs). Here, we introduce a Co/CoP heterojunction embedded in a nitrogen‐doped carbon matrix on carbon cloth (Co‐CoP@NC/CC). The intimate heterojunction interface drives electron transfer from metallic Co to CoP, optimally tuning the adsorption of oxygen‐containing intermediates and markedly enhancing both ORR and OER activities. Operando X‐ray absorption fine structure (XAFS) spectroscopy uncovers dynamic, reversible transformation of Co─P ⇌ Co─O and Co─Co ⇌ Co─O─Co species during each charge‐discharge cycle, which underpin the enhanced performance and durability of ZABs. Consequently, Co‐CoP@NC/CC achieves a charge‐discharge voltage gap of just 0.76 V at 10 mA cm −2 in aqueous ZABs and sustains stable cycling for over 1100 h. Moreover, flexible ZABs incorporating this electrocatalyst operate robustly across an extended temperature range, maintaining continuous performance for 350 h at −60°C. This study is expected to expedite the practical deployment of advanced bifunctional electrocatalysts in next‐generation energy conversion devices.