Mixed polyanionic compounds are potential cathode materials for sodium-ion batteries. Herein, considering the advantages of the strong inductive effect of sulfate and the diverse, flexible coordination modes of oxalate, we systematically explored mixed sulfate-oxalate systems and obtained three sodium-contained polyanionic compounds. Interestingly, the novel three-dimensional Na₂Co(C₂O₄)(SO₄)·xH₂O (x=1–1.5) was found to be a promising cathode material for sodium-ion batteries with good electrochemical activity at high voltage. The present study sets an example of exploring sodium-storage materials in the mixed polyanionic family and provides new insights into designing novel high-voltage cathodes for sodium-based energy storage devices.

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中文翻译：

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混合聚阴离子化合物作为钠离子电池高压正极材料的探索

混合聚阴离子化合物是钠离子电池的潜在正极材料。在此，考虑到硫酸盐强诱导作用和草酸盐多样、灵活的配位方式的优点，我们系统地探索了混合硫酸盐-草酸盐体系，得到了三种含钠聚阴离子化合物。有趣的是，新型三维Na ₂ Co(C ₂ O ₄ )(SO ₄ )·xH ₂ O (x=1–1.5)被发现是一种有前途的钠离子电池正极材料，在高温下具有良好的电化学活性。电压。本研究树立了探索混合聚阴离子家族中钠存储材料的范例，并为设计用于钠基储能装置的新型高压阴极提供了新的见解。

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