Potassium-ion batteries (KIBs) are an attractive energy storage system due to their advantages of low cost and abundant potassium resources. However, their rapid development is greatly impeded by their low capacity and poor stability, due in particular to their much larger volumetric expansion compared to transition metal lithium-ion batteries. Herein, we report a new etching route to fabricate a new class of zero-strain potassium fluoromanganate hollow nanocubes (KMnF-NCs) for boosting the performance of KIBs in terms of capacity, rate capability and cycling stability. The as-made KMnF-NCs containing rich K and F vacancies exhibit a high capacity and super high stability by showing a specific capacity of 110 mA h g⁻¹ even after 10 000 cycles, which is the best stability for KIBs. In situ X-ray diffraction and the first-principles calculations reveal a new storage mechanism for KIBs, in which the intercalation/deintercalation of K ions into/from the K and F vacancies (as a battery behavior) and the adsorption/desorption onto/from the surface (as a pseudocapacitance characteristic) are the key to increasing the capacity of KIBs. Most importantly, we found that during the discharge process, the volume expansion of the etched KMnF-NC was only 1.4%, which is much lower as compared to well-known negative materials, showing great potential as a new class of high-performance zero-strain negative materials for KIBs.

中文翻译：

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零应变K _0.6 Mn ₁ F _2.7空心纳米立方体，用于超稳定的钾离子存储†

钾离子电池（KIBs）具有低成本和丰富的钾资源的优点，是一种有吸引力的能量存储系统。然而，由于其低容量和较差的稳定性，极大地阻碍了它们的快速发展，特别是由于与过渡金属锂离子电池相比，其更大的体积膨胀。在这里，我们报告了一条新的蚀刻路线，以制造新型的零应变氟代锰酸钾空心纳米立方体（KMnF-NCs），以提高KIBs在容量，速率能力和循环稳定性方面的性能。含有丰富的K和F空位的KMnF-NCs甚至在经过10 000次循环后仍显示出110 mA hg ^-1的比容量，从而显示出高容量和超高稳定性，这对于KIB来说是最佳的稳定性。原位X射线衍射和第一性原理计算揭示了一种新的KIBs储存机理，其中K离子向K / F空位中的嵌入/脱嵌（作为电池行为）以及K / F空位中的吸附/解吸。表面（作为伪电容特性）是增加KIB容量的关键。最重要的是，我们发现在放电过程中，蚀刻的KMnF-NC的体积膨胀仅为1.4％，与众所周知的负极材料相比要低得多，显示出作为新型高性能零合金的巨大潜力-为KIBs过滤负性材料。