Co<sub>9</sub>S<sub>8</sub>@NiFe-LDH Bifunctional Electrocatalysts as High-Efficiency Cathodes for Zn–Air Batteries
Yang Zhou, Jiaqi Si, Hongmei Wang, Xiaofeng Li, Sen Zhang, Chao Deng
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 Co 9 S 8 nanorods loaded with NiFe-LDH nanosheets (Co 9 S 8 @NiFe-LDH) was constructed. Co 9 S 8 @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). Co 9 S 8 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 Co 9 S 8 nanorods. Benefiting from such a delicate structural design, the OER potential of Co 9 S 8 @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 RuO 2, indicating its excellent OER activity close to that of noble metal catalysts. The prepared zinc–air cell based on the Co 9 S 8 @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.