Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because the large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g−1 in half-cells at a scan rate of 5 mV s−1, corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g−1 in full cells after 5,000 cycles at 10 C). The promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.
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机译:与其他碱金属离子相比,使用钾离子作为电荷载体的水性电化学储能装置具有较高的安全性,较低的成本和出色的运输性能,因此具有吸引力。然而,难以容纳具有令人满意的容量和循环能力的钾离子,因为钾离子的大离子半径甚至在层状电极中也会引起结构变形和不稳定性。在这里,我们报告水诱导钒氧八面体的结构重排,并增强了高度无序的嵌入钾的钒氧化物纳米片的稳定性。与结构水结合的氧化钒纳米片具有高容量(183 mAh g -1 sup>在半电池中,扫描速率为5 mV s -1 sup>,对应于0.89电荷)每钒中)和极好的循环能力(在10 C下进行5,000次循环后,在全电池中为62.5 mAh g -1 sup>)。结构水对无序氧化钒纳米片的促进作用将有助于从地球上富集的元素中探索无序结构,以用于电化学储能。
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