Hollow Co3O4 Nanosphere Embedded in Carbon Arrays for Stable and Flexible Solid‐State Zinc–Air Batteries

• Published in: Advanced materials (Weinheim) 2017-11, Vol.29 (44), p.n/a
• Main Authors: Guan, Cao, Sumboja, Afriyanti, Wu, Haijun, Ren, Weina, Liu, Ximeng, Zhang, Hong, Liu, Zhaolin, Cheng, Chuanwei, Pennycook, Stephen J., Wang, John
• Format: Article
• Language: English
• Subjects: bifunctional electrocatalysts; Carbon; Catalysis; Catalysts; Cathodes; Cloth; Coating effects; Cobalt oxides; Conversion coating; flexible Zn–air batteries; hollow Co3O4 nanospheres; Iridium; Kirkendall effect; Materials science; Metal air batteries; metal–organic frameworks; Nanospheres; Open circuit voltage; Oxygen evolution reactions; Platinum; Rechargeable batteries; Scale (corrosion); Solid state; Structural hierarchy; Zinc; Zinc-oxygen batteries
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201704117

Highly active and durable air cathodes to catalyze both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are urgently required for rechargeable metal–air batteries. In this work, an efficient bifunctional oxygen catalyst comprising hollow Co3O4 nanospheres embedded in nitrogen‐doped carbon nanowall arrays on flexible carbon cloth (NC‐Co3O4/CC) is reported. The hierarchical structure is facilely derived from a metal–organic framework precursor. A carbon onion coating constrains the Kirkendall effect to promote the conversion of the Co nanoparticles into irregular hollow oxide nanospheres with a fine scale nanograin structure, which enables promising catalytic properties toward both OER and ORR. The integrated NC‐Co3O4/CC can be used as an additive‐free air cathode for flexible all‐solid‐state zinc–air batteries, which present high open circuit potential (1.44 V), high capacity (387.2 mAh g−1, based on the total mass of Zn and catalysts), excellent cycling stability and mechanical flexibility, significantly outperforming Pt‐ and Ir‐based zinc–air batteries. An efficient bifunctional oxygen catalyst comprising hollow Co3O4 nanospheres embedded in N‐doped carbon nanowall arrays (NC‐Co3O4) is facilely fabricated from a metal–organic framework. The additive‐free NC‐Co3O4 electrode can be directly utilized as an efficient air cathode for a flexible solid‐state Zn–air battery, which demonstrates much improved cycling stability and mechanical flexibility over Pt‐ and Ir‐based zinc–air batteries.