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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.

3D printing can allow for the efficient manufacturing of elaborate structures difficult to realise conventionally without waste, such as the hollow geometries of nickel-based superalloy aeronautic components. To fully exploit this method, we must move towards new alloys and processes. Conventional superalloy manufacturing Superalloys, a family of metal mixes based on nickel, cobalt, or iron, are resistant to high temperature deformation, corrosion and oxidation, particularly when operating at elevated temperature close to their melting point. They were first developed for gas turbine components in turbojet engines, and are now widely used for high temperature applications in the aerospace and power generation industries. To achieve these high temperature properties (both mechanical and chemical), microstructural control is critical and is enabled by a combination of specific alloying element additions and careful manufacturing processes. Nickel-based superalloys, the earliest and best-developed superalloy family, rely on a twophase microstructure consisting of a strengthening phase-a dispersion of (Ni,Co) 3 (Al,Ti,Ta) precipitates (of L1 2 crystallography) called γ′-grown in a matrix of Cr-enriched Ni. Other alloying elements such as refractories (Re, Mo, W) or metalloids (B, C) may also be added. Based on their chemistry, these alloys are some of the most complex humanity has designed. During conventional processing, this crucial precipitation occurs via a diffusion-controlled reaction during cooling in the temperature range 1000-750°C 1. Manufacturing is traditionally the 'Achilles' heel' of superalloy applications-structurally sound mechanical properties have not been achieved without long-winded and costly subtractive manufacturing via machining of castings. Today, we still use precision investment casting processes that date back to classical antiquity. For example, to produce a jet engine turbine blade, both a wax model and silica-based replica of the cooling channels are needed to create a ceramic mould for every component produced, into which kilograms of molten metal are cast under vacuum. Cooling to ambient conditions takes several hours, and it is impossible to suppress the precipitation of the γ′ precipitates during cooling; moreover, very careful subsequent heat treatment of several hours at~1300°C is needed-just below the melting temperature-to reduce chemical dendritic segregation from the casting route. Finally, machining is required to shape the final intricate turbine blade geometry. The investment casting process involves several chemical and process controls with significant waste/scrappage generated during the casting and subsequent machining of the turbine parts: only about 10% of the superalloy ends up as finished goods 2 .

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