Layer‐structured (MoO₂)₂P₂O₇ was prepared through the decomposition of MoO₂HPO₄ and further used as a cathode material for sodium‐ion batteries. Results reveal that the capacity and cycling stability of the (MoO₂)₂P₂O₇/Na battery largely depends on the lower cutoff voltage. When cycling between 4.0 ‐1.5 V, (MoO₂)₂P₂O₇ delivers a capacity of 180 mAh g⁻¹ in the first cycle, but it drops very fast owing to a phase decomposition of the crystal structure to an amorphous one. The cycling stability is still not good when cycling between 4.0 ‐1.7 V. However, when cycling between 4.0 ‐ 2.0 V, the performance can be significantly improved, which delivers 93 mAh g⁻¹ in the first cycle and, after 50 cycles, the capacity can maintain 55 mAh g⁻¹. This is mainly attributed to the stable crystal structure of the Na‐intercalated (MoO₂)₂P₂O₇ electrode. Ex situ X‐ray diffraction examination demonstrates that the volume change of the (MoO₂)₂P₂O₇ electrode during the first charging process is only 1 %.

中文翻译：

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层状钼（Oxy）焦磷酸盐（MoO2）2P2O7作为钠离子电池的阴极材料

通过分解MoO ₂ HPO ₄制备层状（MoO ₂）₂ P ₂ O ₇，并进一步用作钠离子电池的正极材料。结果表明，（MoO ₂）₂ P ₂ O ₇ / Na电池的容量和循环稳定性在很大程度上取决于较低的截止电压。在4.0到1.5 V之间循环时，（MoO ₂）₂ P ₂ O ₇可提供180 mAh g ^-1的容量在第一循环中，由于晶体结构的相分解为非晶态，其下降非常快。在4.0到1.7 V之间循环时，循环稳定性仍然不佳。但是，在4.0到2.0 V之间循环时，性能可以得到显着改善，在第一个循环中可提供93 mAh g ^-1的能量，在50个循环后可提供93 mAh g ^-1的能量。容量可以维持55 mAh g ^-1。这主要归因于Na嵌入（MoO ₂）₂ P ₂ O ₇电极的稳定晶体结构。异位X射线衍射检查表明（MoO ₂）₂ P ₂ O ₇的体积变化 第一次充电过程中的电极仅为1％。