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Zero-strain K0.6Mn1F2.7 hollow nanocubes for ultrastable potassium ion storage

Abstract

Potassium-ion batteries (KIBs) are an attractive energy storage system due to their good advantages of low cost and abundant potassium resource. However, their rapid development is greatly impeded by their low capacity and poor stability in particular due to their much larger volumetric expansion than that of transitional lithium ion batteries. Herein, we report a new etching route to fabricate a new class of zero-stain 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 mAh·g-1 even after 10000 cycles, which is the best stability for KIBs. In-situ X-ray diffraction and the first-principle calculation reveal that they show 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 in increasing the capacity of KIBs herein. Most importantly, we found that during the discharge process, the volume expansion of the etched KMnF-NC is only 1.4%, much lower than those of well-known negative materials, which shows the great potential as a new class of high-performance zero-strain negative materials for KIBs.

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Publication details

The article was received on 04 Jun 2018, accepted on 07 Aug 2018 and first published on 07 Aug 2018


Article type: Paper
DOI: 10.1039/C8EE01611A
Citation: Energy Environ. Sci., 2018, Accepted Manuscript
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    Zero-strain K0.6Mn1F2.7 hollow nanocubes for ultrastable potassium ion storage

    W. A. Wang, Z. Liu, P. Li, G. Suo, S. Gong, C. Lao, Y. Xie, H. Guo, Q. Yu, Z. Wang, K. Han, Q. Wang, M. Qin, K. Xi and X. Qu, Energy Environ. Sci., 2018, Accepted Manuscript , DOI: 10.1039/C8EE01611A

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