Enhancing the cycle life of rechargeable Zn-air batteries via in-situ growth FeNi layered double hydroxide on Co₃O₄ air electrode

As a promising secondary battery, the short cycle life of Zn-air batteries (ZABs) severely limits their further application. The traditional air electrode could not maximize the OER activity of air electrode due to the existence of multiphase interface. In this work, FeNi layered double hydroxide (FeNi-LDH) without further hydrophobic treatment as main OER catalyst was in-situ grown on the initial Co₃O₄ air electrode (Ketjen Black as conductive carbon) surface by electrochemical deposition method. With a FeNi-LDH as main OER active component, assembled ZABs delivered an enhance cycle life of 38.1 h, 3.15 times than initial Co₃O₄ air electrode (12.1 h). The significant increase in cycle life is mainly due to the lower charging voltage caused by the FeNi-LDH layer with better OER catalytic activity than Co₃O₄, which reduces the ORR site inactivation and carbon oxidation rate. Therefore, after using multiwalled carbon nanotubes with better oxidation resistance as the conductive carbon instead of Ketjen Black and increasing the mass loading of Co₃O₄ air electrode from 2.0 to 4.0 mg cm⁻², the FeNi-LDH layer can increase ZABs cycle life from 61.4 to 218.3 h. The in-situ electrodeposition FeNi-LDH on traditional air electrode strategy provides a simple method for enhancing the cycle life of ZABs.