Hierarchical Co3O4 Nano-Micro Arrays Featuring Superior Activity as Cathode in a Flexible and Rechargeable Zinc-Air Battery.

Yaotang Zhong,Jie Yang,Zhenghui Pan,Yitong Lu,Xianshu Wang,Yongcai Qiu,Shuyuan Xu,Weishan Li,Qiming Huang

doi:10.1002/advs.201802243

Abstract

All‐solid‐state zinc–air batteries are characterized as low cost and have high energy density, providing wearable devices with an ideal power source. However, the sluggish oxygen reduction and evolution reactions in air cathodes are obstacles to its flexible and rechargeable application. Herein, a strategy called MOF‐on‐MOF (MOF, metal‐organic framework) is presented for the structural design of air cathodes, which creatively develops an efficient oxygen catalyst comprising hierarchical Co3O4 nanoparticles anchored in nitrogen‐doped carbon nano‐micro arrays on flexible carbon cloth (Co3O4@N‐CNMAs/CC). This hierarchical and free‐standing structure design guarantees high catalyst loading on air cathodes with multiple electrocatalytic activity sites, undoubtedly boosting reaction kinetics, and energy density of an all‐solid‐state zinc–air battery. The integrated Co3O4@N‐CNMAs/CC cathode in an all‐solid‐state zinc–air battery exhibits a high open circuit potential of 1.461 V, a high capacity of 815 mAh g−1 Zn at 1 mA cm−2, a high energy density of 1010 Wh kg−1 Zn, excellent cycling stability as well as outstanding mechanical flexibility, significantly outperforming the Pt/C‐based cathode. This work opens a new door for the practical applications of rechargeable zinc–air batteries in wearable electronic devices.

Highlights

All-solid-state zinc–air batteries are characterized as low cost and have high cost, and high safety.[1–5] the previously reported zinc–air battery (ZAB) have been generally energy density, providing wearable devices with an ideal power source
With no need for sealing, the flexible all-solid-state ZABs have attracted much attention due to the advantages of higher practicability, oxygen catalyst comprising hierarchical Co3O4 nanoparticles anchored in nitrogen-doped carbon nano-micro arrays on flexible carbon cloth (Co3O4@NCNMAs/CC)
The as-formed Co3O4 nanoparticles can be exactly confirmed by X-ray diffraction (XRD) pattern, and all diffraction are well consistent with the Co3O4 (JCPDS # 42-1467) (Figure S6a, Supporting Information)

Summary

Results and Discussion

The unique hierarchical 3D-on-2D structure in ZIF-L-D-Co3O4/ CC provides a great number of electrocatalytic activity sites for charge transfer and paths for mass transfer, which reduce the electrochemical impedance and lead to the excellent performances of ZIF-L-D-Co3O4/CC-based ZAB,[42–44] comparable with other all-solid-state ZABs reported by previous literature (Table S3, Supporting Information).[2,9,10,35,37,45,46]. There is no doubt that the ZIF-L-D-Co3O4/CC-based all-solid-state ZAB is successfully applied to realistic wearable electronic devices, and can push the enormous advance of next-generation flexible energy conversion and storage devices

Conclusion

Experimental Section

Conflict of Interest