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

Abstract

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 Co O nanospheres embedded in nitrogen-doped carbon nanowall arrays on flexible carbon cloth (NC-Co O /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-Co O /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 , based on the total mass of Zn and catalysts), excellent cycling stability and mechanical flexibility, significantly outperforming Pt- and Ir-based zinc-air batteries.

Structural Engineering of Low‐Dimensional Metal–Organic Frameworks: Synthesis, Properties, and Applications

“…[251][252][253][254] Up to now, various 2D MOF-derived nanostructure arrays have been reported, such as Ni-doped Co-Co 2 N nanosheet/carbon cloth, [255] N-doped carbon-Co 3 O 4 sheet/ carbon cloth, [256] Co 3 O 4 @N-doped carbon nanosheet/nickel foam, [257] and CoSe 2 sheets/carbon cloth. to construct MOF arrays.…”

Multidimensional Ordered Bifunctional Air Electrode Enables Flash Reactants Shuttling for High‐Energy Flexible Zn‐Air Batteries

“…This is also supported by ex situ EIS analysis of the MPZ and PZ batteries under OCV, discharged and charged states. [12,19,[50][51][52][53][54][55][56][57][58] Stability of the MPZ and PI batteries are also examined at a high current density of 50 mA cm −2 with cycle period of 20 min. As shown in Figure 5d, R ct of both electrodes expe rience growth after discharge and then charge, and the slopes of the tails at the low frequency are less steep compared with that measured at OCV state, which is likely caused by the depo sition of ZnO on the air electrode during the cycling process.…”

Hollow‐Structured Metal Oxides as Oxygen‐Related Catalysts

“…The strong interaction between Co and N/B in graphene led to the high electrocatalytic activities of the composite. [39] Hierarchical porous Co 3 O 4 nanoboxes were obtained with well-defined interior voids, functional shells and a large surface area. It remains highly efficient whereas no voltage drop was observed after galvanostatically discharged at 50 mA cm −2 for 15 h. [38] Embeded hollow Co 3 O 4 nanospheres into nitrogen-doped carbon nanowall arrays on flexible carbon cloth have been also reported.…”

“…[6][7][8] Due to the complex charge transfer process with four electrons, these oxygen-related catalytic reactions are hampered by the provided to reduce the recombination. [6][7][8] Due to the complex charge transfer process with four electrons, these oxygen-related catalytic reactions are hampered by the provided to reduce the recombination.…”