For sodium-ion batteries, solving the issue of short cycle life is key to their large-scale adoption in the industry, and the electrolyte plays an important role on this. Herein, this work aims to design a practical sodium ion battery electrolyte with industrial application value and introduces anhydride compounds as additives for the first time. Meanwhile, by adjusting the solvent composition and using a combination of ether and ester solvents, the optimal electrolyte formulation of 1 M NaPF₆ (sodium hexafluorophosphate) + DME (glycol dimethyl ether)/VC (vinylidene carbonate) (1 : 1, v/v) + 2 wt% GA (glutaric anhydride) is designed. Na⁺-VC, which has the highest occupied molecular orbital in this electrolyte, is preferentially oxidized to form a cathode electrolyte interface on the cathode. And synchronously, Na⁺-GA with the lowest unoccupied molecular orbital is preferentially reduced to form a surface electrolyte interface on the anode. This electrolyte can achieve simultaneous film formation on both sides of the electrode, thus greatly increasing the cycle life of the sodium-ion battery. For example, the Na‖NVP (sodium vanadium phosphate) battery still maintains a specific capacity of 91.16 mA h g⁻¹ with a capacity retention rate of 85.06% after 2500 cycles. And the NVP‖HC (hard carbon) full battery also maintains a capacity retention rate of 66.50% after 800 cycles. This work will provide important ideas and strong evidence for the industrial application of sodium ion battery electrolytes with long cycle life.

中文翻译：

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由戊二酸酐添加剂实现的超长循环钠离子电池


对于钠离子电池来说，解决循环寿命短的问题是其在工业上大规模采用的关键，而电解液在其中发挥着重要作用。在此，本工作旨在设计一种具有工业应用价值的实用钠离子电池电解液，并首次引入酸酐化合物作为添加剂。同时，通过调整溶剂组成并使用醚和酯类溶剂的组合，设计了 1 M NaPF₆（六氟磷酸钠）+ DME（乙二醇二甲醚）/VC（偏二氧化乙烯碳酸酯）（1 ： 1，v/v）+ 2 wt% GA（戊二酸酐）的最佳电解质配方。Na⁺-VC 在该电解质中具有最高的占据分子轨道，优先被氧化，在阴极上形成阴极电解质界面。同时，具有最低未占据分子轨道的 Na⁺-GA 优先被还原，在阳极上形成表面电解质界面。这种电解液可以在电极的两侧同时形成薄膜，从而大大延长钠离子电池的循环寿命。例如，Na‖NVP（磷酸钒钠）电池在 2500 次循环后仍保持 91.16 mA h ^g-1 的比容量，容量保持率为 85.06%。而 NVP‖HC（硬碳）满电池在 66.50 次循环后也保持了 800% 的容量保持率。这项工作将为长循环寿命钠离子电池电解液的工业应用提供重要思路和有力证据。