The construction of an optimized electrolyte system compatible with layered transition metal (TM) oxides is of great importance to advanced sodium-ion batteries (SIBs). Herein, a low-cost iron-containing manganese-based layered cathode material of Na_0.67Ni_0.15Fe_0.2Mn_0.65O₂ (N-NFM) is prepared through an improved coprecipitation method. Then, the chemical properties of interfaces between the N-NFM cathode and organic liquid electrolytes based on NaClO₄ and NaPF₆ are investigated, respectively. Results show that the cathode electrolyte interphase (CEI) film formed in the NaPF₆-based electrolyte is dense and uniform, which inhibits the dissolution of TM ions effectively and provides a low energy barrier for the transport of Na⁺. Apart from that the CEI film formed in the NaClO₄-based electrolyte contains more organic but less inorganic compounds, resulting in an increase in impedance. In addition, it is believed that the stability of the CEI film is susceptible to the perchlorate with strong oxidizing property. In this role, a small part of the CEI film falls from the cathode surface, accelerating the dissolution of TM ions and leading to the reactivation of electrolyte decomposition.

中文翻译：

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钠离子电池正极与Na0.67Ni0.15Fe0.2Mn0.65O2相容钠盐电解质的选择

构建与层状过渡金属 (TM) 氧化物兼容的优化电解质系统对于先进的钠离子电池 (SIB) 非常重要。在此，通过改进的共沉淀法制备了低成本的Na _0.67 Ni _0.15 Fe _0.2 Mn _0.65 O ₂ (N-NFM)的含铁锰基层状正极材料。然后，分别研究了 N-NFM 正极和基于 NaClO ₄和 NaPF _{6 的}有机液体电解质之间界面的化学性质。结果表明，在 NaPF _{6 中}形成的阴极电解质中间相 (CEI) 膜基电解质致密均匀，有效抑制了TM离子的溶解，为Na ⁺的传输提供了低能垒。除此之外，在基于NaClO ₄的电解质中形成的CEI膜包含更多的有机但更少的无机化合物，导致阻抗增加。此外，认为CEI膜的稳定性易受具有强氧化性的高氯酸盐的影响。在此作用下，一小部分 CEI 膜从阴极表面落下，加速了 TM 离子的溶解并导致电解质分解的重新激活。