Sodium-ion batteries (NIBs) have attracted worldwide attention for next-generation energy storage systems. However, the severe instability of the solid–electrolyte interphase (SEI) formed during repeated cycling hinders the development of NIBs. In particular, the SEI dissolution in NIBs with a high-voltage cathode is more severe than in the case of Li-ion batteries (LIBs) and leads to continuous side reactions, electrolyte depletion and irreversible capacity loss, making NIBs less stable than LIBs. Here we report a rational electrolyte design to suppress the SEI dissolution and enhance NIB performance. Our electrolyte lowers the solvation ability for SEI components and facilitates the formation of insoluble SEI components, which minimizes the SEI dissolution. In addition to the stable SEI on a hard carbon (HC) anode, we also show a stable interphase formation on a NaNi_0.68Mn_0.22Co_0.1O₂ (NaNMC) cathode. Our HC||NaNMC full cell with this electrolyte demonstrates >90% capacity retention after 300 cycles when charged to 4.2 V. This study enables high-voltage NIBs with long cycling performance and provides a guiding principle in electrolyte design for sodium-ion batteries.

钠离子电池（NIB）作为下一代储能系统已经引起了全世界的关注。然而，在重复循环过程中形成的固体电解质界面 (SEI) 的严重不稳定性阻碍了 NIBs 的发展。特别是，具有高压正极的 NIBs 中的 SEI 溶解比锂离子电池 (LIBs) 更严重，并导致持续的副反应、电解质耗尽和不可逆的容量损失，使得 NIBs 不如 LIBs 稳定。在这里，我们报告了一种合理的电解质设计，以抑制 SEI 溶解并提高 NIB 性能。我们的电解质降低了 SEI 组分的溶剂化能力并促进了不溶性 SEI 组分的形成，从而最大限度地减少了 SEI 溶解。除了在硬碳 (HC) 阳极上稳定的 SEI，_0.68 Mn _0.22 Co _0.1 O ₂ (NaNMC)阴极。我们采用这种电解液的 HC||NaNMC 全电池在充电至 4.2 V 时，在 300 次循环后表现出 > 90% 的容量保持率。这项研究使高压 NIBs 具有长循环性能，并为钠离子电池的电解液设计提供了指导原则。