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New Insights into the Electrochemistry Superiority of Liquid Na–K Alloy in Metal Batteries
Author(s) -
Huang Man,
Xi Baojuan,
Feng Zhenyu,
Wu Fangfang,
Wei Denghu,
Liu Jing,
Feng Jinkui,
Qian Yitai,
Xiong Shenglin
Publication year - 2019
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201804916
Subject(s) - materials science , electrochemistry , alloy , electrolyte , faraday efficiency , anode , electrochemical kinetics , chemical engineering , electrode , cathode , battery (electricity) , metal , inorganic chemistry , composite material , metallurgy , chemistry , thermodynamics , power (physics) , physics , engineering
The significant issues with alkali metal batteries arise from their poor electrochemical properties and safety problems, limiting their applications. Herein, TiO 2 nanoparticles embedded into N‐doped porous carbon truncated ocatahedra (TiO 2 ⊂NPCTO) are engineered as a cathode material with different metal anodes, including solid Na or K and liquid Na–K alloy. Electrochemical performance and kinetics are systematically analyzed, with the aim to determine detailed electrochemistry. By using a galvanostatic intermittent titration technique, TiO 2 ⊂NPCTO/NaK shows faster diffusion of metal ions in insertion and extraction processes than that of Na‐ions and K‐ions in solid Na and K. The lower reaction resistance of liquid Na–K alloy electrode is also examined. The higher b ‐value of TiO 2 ⊂NPCTO/NaK confirms that the reaction kinetics are promoted by the surface‐induced capacitive behavior, favorable for high rate performance. This superiority highly pertains to the distinct liquid−liquid junction between the electrolyte and electrode, and the prohibition of metal dendrite growth, substantiated by symmetric cell testing, which provides a robust and homogeneous interface more stable than the traditional solid−liquid one. Hence, the liquid Na–K alloy‐based battery exhibits to better cyclablity with higher capacity, rate capability, and initial coulombic efficiency than solid Na and K batteries.