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Capillary Encapsulation of Metallic Potassium in Aligned Carbon Nanotubes for Use as Stable Potassium Metal Anodes
Author(s) -
Qin Lei,
Lei Yu,
Wang Huwei,
Dong Jiahui,
Wu Yiying,
Zhai Dengyun,
Kang Feiyu,
Tao Ying,
Yang QuanHong
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201901427
Subject(s) - anode , materials science , electrolyte , prussian blue , electrochemistry , chemical engineering , cathode , electrode , wetting , metal , polarization (electrochemistry) , nanotechnology , inorganic chemistry , composite material , metallurgy , chemistry , engineering
Metallic potassium (K) is a desirable anode for potassium secondary batteries due to its low electrode potential in nonaqueous electrolytes and high theoretical capacity. Nevertheless, instability caused by dendritic growth, large volume changes, and parasitic side reactions hamper its practical application. Here, an anode containing metallic K is fabricated by infiltrating an aligned carbon nanotube membrane (ACM) with molten K because of its good wettability to molten K due to the strong capillary forces. The K metal is spatially distributed on the 3D ACM framework, which offers sufficient electrode/electrolyte contact for charge transfer. The robust ACM host provides a large number of K nucleation sites and physically confines the K deposited there, thus mitigating dimensional changes during cycling. The pathways for electrons and ions in the anode are associated to form a mixed conducting network, which is beneficial for the electrochemical redox. Consequently, the anode shows stable plating/stripping profiles with low polarization in symmetric cells using conventional carbonate‐based electrolytes. In addition, dendrite growth is suppressed, and the anode demonstrates excellent suitability when paired with a Prussian blue cathode in a full cell. This design strategy is expected to provide a way to address the problems with using metallic K anodes.