Aqueous Li-ion batteries suffer from parasitic hydrogen evolution due to limited cathodic stability. We introduce in this work a dual-additive strategy combining a persulfate and a fluorinated acrylate in a 21 mol kg^–1 LiTFSI aqueous electrolyte. The additives promote the formation of a bilayer solid electrolyte interphase (SEI) comprising an inorganic LiF-rich inner layer and a hydrophobic organic-rich outer layer, which effectively suppresses hydrogen evolution and inhibits SEI dissolution. With this formulation, a LiMn₂O₄/Li₄Ti₅O₁₂ cell is shown to retain over 80% of its initial capacity after 300 cycles, outperforming both the baseline and single-additive controls. The persulfate–acrylate pair likewise improves the cycling stability in other aqueous electrolytes. We also extended the concept to alternative initiator–monomer combinations, demonstrating its versatility in interfacial engineering. By enabling robust SEI formation, this strategy addresses a key limitation of aqueous Li-ion batteries and supports their practical deployment.

中文翻译：

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双重电解质添加剂抑制水系锂离子电池中的析氢

由于阴极稳定性有限，水性锂离子电池会发生寄生析氢。在这项工作中，我们引入了一种双添加剂策略，将过硫酸盐和氟化丙烯酸酯结合在 21 mol kg^–1 LiTFSI 水性电解质中。添加剂促进双层固体电解质界面 （SEI） 的形成，包括富含无机 LiF 的内层和疏水性的富含有机物的外层，有效抑制析氢并抑制 SEI 溶解。使用这种配方，LiMn₂O₄/Li₄Ti₅O₁₂ 电池在 300 次循环后仍能保留其 80% 以上的初始容量，性能优于基线和单一添加剂对照。过硫酸盐-丙烯酸酯对同样提高了其他水性电解质中的循环稳定性。我们还将这一概念扩展到替代引发剂-单体组合，展示了它在界面工程中的多功能性。通过实现稳健的 SEI 形成，该策略解决了水性锂离子电池的一个关键限制，并支持其实际部署。