Co9S8@NiFe-LDH Bifunctional Electrocatalysts as High-Efficiency Cathodes for Zn–Air Batteries

Abstract

Exploring new cathodes with high-energy storage is a key issue for zinc–air batteries. Herein, a multidimensional free-standing cathode catalyst consisting of Co9S8 nanorods loaded with NiFe-LDH nanosheets (Co9S8@NiFe-LDH) was constructed. Co9S8@NiFe-LDH not only provides a conductive backbone for fast electron/ion transfer but also has abundant active sites to accelerate the oxygen reduction/evolution reaction (ORR/OER). Co9S8 nanorods with high ORR activity and good electrical conductivity were grown in situ on carbon cloth, and NiFe LDH nanorods were successfully loaded on the surface of Co9S8nanorods. Benefiting from such a delicate structural design, the OER potential of Co9S8@NiFe-LDH is 1.62 V at 10 mA cm–2, which is slightly higher than the OER potential of 1.61 V for the commercial noble metal RuO2, indicating its excellent OER activity close to that of noble metal catalysts. The prepared zinc–air cell based on the Co9S8@NiFe-LDH cathode has an ideal specific capacity of 780.5 mAh g–1 at 10 mA cm–2, a high power density of 148 mW cm–2 at 180 mA cm–2, and a good 200 h cycle stability. Therefore, this work paves the way for catalyst design and promotes the development of multidimensional composite-structured cathode materials for zinc–air batteries.