Aqueous Zn‐ion batteries (AZIBs) are regarded as a promising alternative to the widely used lithium‐ion batteries in large‐scale energy storage systems. The researches on the development of novel aqueous electrolyte to improve battery performance have also attracted great interest since the electrolyte is a key component for Zn2+ migration between cathode and anode. Herein, we briefly summarized and illuminated the recent development tendency of aqueous electrolyte for AZIBs, then deeply analyzed its existing issues (water decomposition, cathode dissolution, corrosion and passivation, and dendrite growth) and discussed the corresponding optimization strategies (pH regulation, concentrated salt solution, electrolyte composition design, and functional additives). The internal mechanisms of these strategies were further revealed and the relationships between issues and solutions were clarified, which could guide the future development of aqueous electrolytes for AZIBs.

Developing a highly stable and dendrite-free zinc anode is essential to the commercial application of zinc metal batteries. However, the understanding of zinc dendrites formation mechanism is still insufficient. Herein, for the first time, we discover that the interfacial heterogeneous deposition induced by lattice defects and epitaxial growth limited by residual stress are intrinsic and critical causes for zinc dendrite formation. Therefore, an annealing reconstruction strategy was proposed to eliminate lattice defects and stresses in zinc crystals, which achieve dense epitaxial electrodeposition of zinc anode. The as-prepared annealed zinc anodes exhibit dendrite-free morphology and enhanced electrochemical cycling stability. This work first proves that lattice defects and residual stresses are also very important factors for epitaxial electrodeposition of zinc in addition to crystal orientation, which can provide a new mechanism for future researches on zinc anode modification.

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Cu (1 1 1) facet exposure can promote zinc nucleation and uniformize zinc growth. [6] The expensive Cu (1 0 0) single-crystal has also been used to inhibit the generation of zinc dendrites. [7] However, there is a limited prospect for graphene, copper nanowires, copper foam, and copper single-crystal because of their high cost. [8] Therefore, it is essential to develop more efficient and low-cost substrate regulation strategies.Electrolytic copper foil is a widely used commercial current collector with mature fabrication technology and acceptable cost. [9] Selective facet exposure during the electrolysis of copper foils has been proven to be easily achievable in existing copper foil preparations. [10] It may be a promising method to prepare specially oriented copper foils by electrolysis for practical applications. Various facets such as (1 1 1), (2 0 0), (2 2 0), and (3 1 1) may be exposed during the copper electrolysis process. [11] If the zinc deposition activity of these facets is identified, zinc deposition can be efficiently regulated by selectively exposing the most active facet. In addition to the effect of substrate facet exposure on zinc deposition, the exposed zinc facets during the deposition process can also influence the subsequent zinc deposition because of the different activities of the different zinc facets. [12] Crystal growth theory suggests that the fast-growing crystalline facets tend to disappear gradually, while slow-growing facets are preferentially exposed. [13] This critical conclusion is usually overlooked by some researchers who determine the preferential growth or exposure of crystal facets only by the intensity of the X-ray diffraction (XRD) peaks. This approach is usually inadequate because the relative peak intensities of bulk samples are related to the grain alignment orientation. [14] Electron backscatter diffraction (EBSD) can be used to precisely analyze the correlation between crystal facet growth and exposure to understand the zinc growth mechanism during electrodeposition. Based on the above considerations, fabrication of copper substrates with high active facet exposure by electrolysis and in-depth study of zinc growth mechanism on substrates are important to enhance its reversibility for zinc plating and stripping.In this work, we reveal the highest zinc deposition activity of Cu (2 2 0) facet in comparison with other low-index crystal facets by optical microscopy and EBSD techniques. An industrial electrolysis method is proposed to construct Cu (2 2 0) substrate with highly preferential orientation, denoted as PCu. This uniformly oriented substrate with zincophilicity can playThe most commonly used zinc foil anode for aqueous zinc-ion batteries suffers from poor cycle stability and low zinc utilization. Zinc-plated anodes on the host materials with high zincophilicity and stability are receiving increasing attention to alleviate these above issues. Here, the high zinc deposition activity of Cu (2 2 0) is confirmed through experimental observations and theoretical cal...

Aqueous zinc‐ion batteries (AZIBs) have drawn the attention of numerous researchers owing to their high safety and cost‐effectiveness. However, the dendrite growth and side reactions of the zinc (Zn) anodes limit their further practical applications. Herein, a porous amorphous silicon nitride protective layer with high zincophobicity is constructed on the Zn anode surface, which can guide the uniform stripping/plating of Zn2+ underneath the protective layer through its isotropic Zn affinity to alleviate the growth of dendrites and by‐products. As a result, the amorphous silicon nitride‐protected Zn anode can maintain a stable Coulombic efficiency (CE) of 98.8% and low voltage hysteresis for 710 cycles in the half cell. The full cell with the as‐prepared Zn anode can deliver excellent electrochemical performances (89.0% capacity retention and 144.4 mAh g−1 discharge capacity after 1000 cycles at 4 A g−1). This work reveals the key role of uniform metal affinity induced by the amorphous materials in the interface modification of metal anodes, which is instructive for the design of stable metal anodes.

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The amide additives acting as hydrogen-bonding ligands effectively break the cross-linking structures between water molecules and increase the entropy of mixed solvents, thus enabling the mixed solvent with an ultralow...