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Issue 2, 2019
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Extremely stable antimony–carbon composite anodes for potassium-ion batteries

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Potassium-ion batteries (PIBs) have been considered as promising alternatives to lithium-ion batteries due to potassium's high natural abundance of 2.09 wt% (vs. 0.0017 wt% for Li) and K/K+ having a low redox potential of −2.93 V (vs. −2.71 V for Na/Na+). However, PIB electrodes still suffer huge challenges due to the large K-ion radius and slow reaction dynamics. Herein, we report a high-capacity Sb@CSN composite anode with Sb nanoparticles uniformly encapsulated by a carbon sphere network (CSN) for PIBs. First-principles computations and electrochemical characterization confirm a reversible sequential phase transformation of KSb2, KSb, K5Sb4, and K3Sb during the potassiation/depotassiation process. In a concentrated 4 M KTFSI/EC + DEC electrolyte, the Sb@CSN anode delivers a high reversible capacity of 551 mA h g−1 at 100 mA g−1 after 100 cycles with an extremely slow capacity decay of only 0.06% per cycle from the 10th to 100th cycle; when at a high current density of 200 mA g−1, the Sb@CSN anode still maintains a capacity of 504 mA h g−1 after 220 cycles. The Sb@CSN anodes demonstrate one of the best electrochemical performances for all K-ion battery anodes reported to date. The exceptional performance of Sb@CSN should be attributed to the efficient encapsulation of small Sb nanoparticles in the conductive carbon network as well as the formation of a robust KF-rich SEI layer on the Sb@CSN anode in the concentrated 4 M KTFSI/EC + DEC electrolyte.

Graphical abstract: Extremely stable antimony–carbon composite anodes for potassium-ion batteries

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Article information

27 Sep 2018
08 Jan 2019
First published
08 Jan 2019

Energy Environ. Sci., 2019,12, 615-623
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Author version available

Extremely stable antimony–carbon composite anodes for potassium-ion batteries

J. Zheng, Y. Yang, X. Fan, G. Ji, X. Ji, H. Wang, S. Hou, M. R. Zachariah and C. Wang, Energy Environ. Sci., 2019, 12, 615
DOI: 10.1039/C8EE02836B

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