Achieving Ultrahigh‐Rate Planar and Dendrite‐Free Zinc Electroplating for Aqueous Zinc Battery Anodes

Abstract

attractive for future grid-level energy storage applications. Metallic Zn, as the ideal anode for AZBs, has the highest theoretical capacity (5851 mAh mL −1 ). It is also non-toxic, non-flammable, abundant, and has good electrical conductivity and water stability. [1][2][3][4][5] However, conventional metallic Zn anodes suffer from severe dendrite formation during cycling, causing serious problems like poor reversibility, voltage hysteresis, increased parasitic reactions, shorting-induced battery failures, and other issues. [1,3,6] These dendritic structures, either rarefied needle, or non-planar platelet deposits, preferentially form at irregular or defective areas of the electrode where the localized current density is highest and the initial nucleation event is most likely, [7] and is exacerbated by cycling at high current densities and capacities. [8,9] Strategies for controlling and suppressing dendritic growth have revolved around manipulating the electrolyte, typically by inclusion of additives, [10][11][12][13][14][15] or by engineering the electrode into a high-surface-area sponge, [16][17][18] or with a protective surface coating, [19] in order to suppress dendrite formation.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 −2 can be achieved at an unprecedentedly high current density of 200 mA cm −2 . This dendrite-free electrode is well maintained even after prolonged cycling (>1200 cycles at 50 mA cm −2 ). 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.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202202552.

Unraveling the Interphasial Chemistry for Highly Reversible Aqueous Zn Ion Batteries

“…It is noted that a certain amorphous structure might still exist on the Zn electrodes which is not detected by XRD. The intensity proportion of (002) Zn and (100) Zn peaks of the Zn deposition is enhanced after the addition of acetate additives, suggesting the preferential deposition of (002) Zn planes as shown in Figure a–f which is consistent with previous reports. , Moreover, the (002) Zn /(100) Zn proportion of Zn deposition increases along with cycling (Figure S15), which enables homogeneous Zn deposition and stable cycling as discussed in Figure d,e.…”

Emerging strategies for steering orientational deposition toward high-performance Zn metal anodes

“…5(a) and (b)), leading to the formation of a homoepitaxial layer rather than the case of current collector design via heteroepitaxy. 93 In this realm, many efforts have been made to regulate Zn deposition morphology at the Zn/electrolyte interface.…”

High‐Index Zinc Facet Exposure Induced by Preferentially Orientated Substrate for Dendrite‐Free Zinc Anode

“…The Zn (0 0 1) facet exhibits the lowest surface energy among all zinc crystal facets, which infers that the Zn (0 0 1) facet tends to be preferentially exposed during the zinc nucleation stage based on crystal growth theory and can provide a substrate for homoepitaxial growth for subsequent Zn (0 0 1) facet growth. [24] At a high zinc deposition capacity, the active deposition sites of copper are occupied by zinc and the subsequent zinc is deposited not on copper surface but on the previously deposited zinc. Zn (0 0 1) texture is formed on PCu at the initial stage of zinc nucleation and the zinc deposits still consist of stacked hexagonal flakes by the continuous homoepitaxial growth of Zn (0 0 1) even though the deposition capacity increases.…”