Modulation of solvation structure and electrode work function by an ultrathin polymer of intrinsic microporosity layer to enhance the reaction kinetics and uniformity of a Zn metal electrode

J. Heo, Y.-E. Hwang, G. Doo, J. Jung, K. Shin, D.-Y. Koh*, H.-T. Kim*, Small, 18, 2201163 (2022)

https://doi.org/10.1002/smll.202201163

Heo and Hwang equally contributed

Zinc ion batteries are promising candidates for large-scale energy storage systems. However, they suffer from the critical problems of insufficient cycling stability due to internal short-circuiting by zinc dendrites and zinc metal orphaning. In this work, a polymer of intrinsic microporosity (PIM-1) is reported as an ion regulating layer and an interface modulator, which promotes a uniform Zn plating and stripping process. According to spectroscopic analyses and computational calculations, PIM-1 enhances the reaction kinetics of a Zn metal electrode by altering the solvation structure of Zn2+ ions and increasing the work function of the Zn surface. As a result, the PIM-1 coating significantly improves the cyclability (1700 h at 0.5 mA cm−2) and Coulombic efficiency (99.6% at 3 mA cm−2) of the Zn/Zn2+ redox reaction. Moreover, the PIM-1 coated Zn operates for more than 200 h at 70% Zn utilization even under 10 mA cm−2 and 110 h at 95% Zn utilization of the Zn metal electrode. A Zn||V2O5 full cell employing the PIM-1 layer exhibits seven times longer cycle life compared to the cell using bare Zn. The findings in this report demonstrate the potential of microporous materials as a key ingredient in the design of reversible Zn electrodes.