Joule
Volume 3, Issue 5, 15 May 2019, Pages 1289-1300
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Article
A Metal-Organic Framework Host for Highly Reversible Dendrite-free Zinc Metal Anodes

https://doi.org/10.1016/j.joule.2019.02.012Get rights and content
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Highlights

  • MOF is first employed as the host for high efficiency and dendrite-free Zn anode

  • The results show a new and low-cost avenue for developing highly reversible zinc anode

  • The AC//Zn@ZIF-8-500 supercapacitor delivers 72% capacity retention after 20,000 cycles

  • The I2//Zn@ZIF-8-500 battery shows a long life of 1,600 cycles

Context & Scale

Aqueous Zn-based batteries and supercapacitors have been considered as promising candidates for electrochemical energy storage devices because of the inherent advantages of metallic Zn. Unfortunately, the stability of the Zn anode in the mild electrolyte is still much limited by the dendrite growth, undesired hydrogen evolution, and the formation of inert “dead” Zn. Here, we report the utilization of MOF ZIF-8 treated with an optimized temperature (500°C) as a host material for the development of highly stable and dendrite-free Zn metal anodes. The ZIF-8-500 anode exhibits unprecedented reversibility of Zn plating/stripping behavior, high Coulombic efficiency (close to 100%), and dendrite-free Zn. The novel Zn@ZIF-8-500 anode coupled with an activated carbon cathode or an I2 cathode works well. This work represents a new and low-cost avenue for developing a highly reversible zinc metal anode.

Summary

Zinc metal featuring low cost, high capacity, low potential, and environmental benignity is an exciting anode material for aqueous energy storage devices. Unfortunately, the dendrite growth, limited reversibility, and undesired hydrogen evolution hinder its application. Herein, we demonstrate that MOF ZIF-8 annealed at 500°C (ZIF-8-500) can be used as a host material for high-efficiency (approximately 100%) and dendrite-free Zn plating and stripping because of its porous structure, trace amount of zinc in the framework, and high over-potential for hydrogen evolution. The Zn@ZIF-8-500 anode (i.e., ZIF-8-500 pre-plated with 10.0 mAh cm−2 Zn) is coupled with an activated carbon cathode or an I2 cathode to form a hybrid supercapacitor or a rechargeable battery, respectively. The supercapacitor delivers a high energy density of 140.8 Wh kg−1 (normalized to the mass of active materials in electrodes) while retaining 72% capacity over 20,000 cycles, and the battery shows a long life of 1,600 cycles.

Keywords

dendrite-free zinc anode
MOF host
aqueous Zn battery
Zn-based supercapacitor

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