Owing to zinc dendrites and parasitic reactions, aqueous Zn-metal batteries often suffer from poor reversibility and cyclability. Electrolyte additives present a promising strategy to improve Zn anode stability. However, the ever-evolving perspectives and mechanisms, paradoxically, complicate battery design, causing a scenario where any electrolyte additive seems to be effective. Herein, it is taken ionic liquid (IL) additives as an example and detailed explored the impact of three typical IL anions, namely OTF⁻, TFA⁻, and BF₄⁻. It is identified that the primary determinant of electrolyte additives as their electrical double layer (EDL) structures and their subsequent solid-electrolyte interface (SEI) composition. An advantageous EDL structure, akin to an ion-shield, can reduce the absorption of H₂O molecules, which further enrich the SEI with zincophilic and hydrophobic components, thereby mitigating parasitic reactions and Zn dendrite formation. As a result, the Zn||Zn cell with optimal [EMIM]OTF additives demonstrates an exceptional cycling life under challenging conditions, its cumulative plated capacity surpasses most previously reported results by utilizing different IL additives. This work extends beyond performance enhancements, representing a valuable exploration of key criteria for electrolyte additives is believed. These insights are expected to offer fundamental guidance for future research and electrolyte design.

中文翻译：

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增强锌金属阳极稳定性：电解质添加剂对离子屏蔽状双电层和稳定固体电解质界面的关键影响

由于锌枝晶和寄生反应，水系锌金属电池通常可逆性和循环性较差。电解质添加剂是提高锌负极稳定性的一种有前景的策略。然而，矛盾的是，不断发展的观点和机制使电池设计变得复杂，导致任何电解质添加剂似乎都有效的情况。本文以离子液体（IL）添加剂为例，详细探讨了三种典型IL阴离子OTF ^-、TFA ^-和BF ₄ ^-的影响。据认为，电解质添加剂的主要决定因素是其双电层（EDL）结构及其随后的固体电解质界面（SEI）组成。类似于离子屏蔽的有利的EDL结构可以减少H ₂ O分子的吸收，这进一步使SEI富含亲锌和疏水成分，从而减轻寄生反应和锌枝晶的形成。因此，具有最佳 [EMIM]OTF 添加剂的 Zn||Zn 电池在具有挑战性的条件下表现出出色的循环寿命，其累积镀覆容量超过了大多数先前报道的使用不同 IL 添加剂的结果。这项工作超出了性能增强的范围，相信代表了对电解质添加剂关键标准的有价值的探索。这些见解预计将为未来的研究和电解质设计提供基本指导。