Pu Shengda D, Gong Chen, Tang Yuanbo T, Ning Ziyang, Liu Junliang, Zhang Shengming, Yuan Yi, Melvin Dominic, Yang Sixie, Pi Liquan, Marie John-Joseph, Hu Bingkun, Jenkins Max, Li Zixuan, Liu Boyang, Tsang S C Edman, Marrow T James, Reed Roger C, Gao Xiangwen, Bruce Peter G, Robertson Alex W
Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
The Faraday Institution, Quad One, Becquerel Avenue, Harwell Campus, Didcot, OX11 0RA, UK.
Adv Mater. 2022 Jul;34(28):e2202552. doi: 10.1002/adma.202202552. Epub 2022 Jun 4.
Despite being one of the most promising candidates for grid-level energy storage, practical aqueous zinc batteries are limited by dendrite formation, which leads to significantly compromised safety and cycling performance. In this study, by using single-crystal Zn-metal anodes, reversible electrodeposition of planar Zn with a high capacity of 8 mAh cm can be achieved at an unprecedentedly high current density of 200 mA cm . This dendrite-free electrode is well maintained even after prolonged cycling (>1200 cycles at 50 mA cm ). Such excellent electrochemical performance is due to single-crystal Zn suppressing the major sources of defect generation during electroplating and heavily favoring planar deposition morphologies. As so few defect sites form, including those that would normally be found along grain boundaries or to accommodate lattice mismatch, there is little opportunity for dendritic structures to nucleate, even under extreme plating rates. This scarcity of defects is in part due to perfect atomic-stitching between merging Zn islands, ensuring no defective shallow-angle grain boundaries are formed and thus removing a significant source of non-planar Zn nucleation. It is demonstrated that an ideal high-rate Zn anode should offer perfect lattice matching as this facilitates planar epitaxial Zn growth and minimizes the formation of any defective regions.
尽管水系锌电池是电网级储能最有前景的候选者之一，但实际应用的水系锌电池受到枝晶形成的限制，这导致安全性和循环性能显著受损。在本研究中，通过使用单晶锌金属阳极，在前所未有的200 mA cm 的高电流密度下，可以实现平面锌的可逆电沉积，其容量高达8 mAh cm 。即使在长时间循环（50 mA cm 下>1200次循环）后，这种无枝晶电极仍能很好地保持。这种优异的电化学性能归因于单晶锌抑制了电镀过程中缺陷产生的主要来源，并极大地有利于平面沉积形态。由于形成的缺陷位点极少，包括那些通常会出现在晶界处或用于适应晶格失配的位点，即使在极端电镀速率下，枝晶结构也几乎没有成核的机会。这种缺陷的稀缺部分归因于合并的锌岛之间完美的原子拼接，确保不会形成有缺陷的浅角晶界，从而消除了非平面锌成核的一个重要来源。结果表明，理想的高倍率锌阳极应提供完美的晶格匹配，因为这有利于平面外延锌生长，并最大限度地减少任何缺陷区域的形成。
