Construction of ultra-stable NiFe armored catalyst for liquid and flexible quasi-solid-state rechargeable Zn–air batteries

The commercial application of non-precious metal-based electrocatalysts is not only limited by the intrinsic activity of the catalysts, but also the stability of the catalysts is extremely important. Herein, we fabricated an ultra-stable NiFe armored catalyst (Ar-NiFe/NC) by a simple secondary pyrolysis strategy. The as-obtained Ar-NiFe/NC electrocatalyst exhibits an excellent bifunctional oxygen electrocatalytic performance with an activity indicator ∆E of 0.74 V vs. reversible hydrogen electrode (RHE). More importantly, the Ar-NiFe/NC electrocatalyst also shows a remarkable operational and storage stability. After accelerated durability test (ADT) cycles, no obvious degradation of oxygen electrocatalytic performance could be observed. In addition, the Ar-NiFe/NC electrocatalyst still exhibits an unbated oxygen electrocatalytic performance comparable to fresh catalysts after three months of air-exposed storage. The assembled liquid and flexible quasi-solid-state rechargeable Zn–air batteries with the Ar-NiFe/NC electrocatalyst exhibit impressive performance. The liquid rechargeable Zn–air batteries possess a high open-circuit voltage (OCV) of 1.43 V and a salient peak power density of 146.40 mW·cm⁻², while the flexible quasi-solid-state rechargeable Zn–air batteries also exhibit an excellent OCV of 1.60 V and an exciting peak power density of 41.99 mW·cm⁻².