期刊
ACS NANO
卷 12, 期 8, 页码 8297-8307出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b03572
关键词
Mg-ion battery; magnesium; energy storage; nanocrystal; synthesis
类别
资金
- Innosuisse, Swiss Innovation Agency
- ETH Zurich [ETH-56 12-2]
- Innosuise, Swiss Innnovation Agency, CTI project [14698.2 PFIW-IW]
- Swiss National Science Foundation (SNF Ambizione Energy) [PZENP2_154287]
- Scholarship Fund of the Swiss Chemical Industry (SSCI Award 2015)
At present, the technical progress of secondary batteries employing metallic magnesium as the anode material has been severely hindered due to the low oxidation stability of state-of-the-art Mg electrolytes, which cannot be used to explore high-voltage (>3 V versus Mg-2+/Mg) cathode materials. All known electrolytes based on oxidatively stable solvents and salts, such as Mg(ClO4)(2) and Mg bis(trifluoromethanesulfonimide), react with the metallic magnesium anode, forming a passivating layer at its surface and preventing the reversible plating and stripping of Mg. Therefore, in a near-term effort to extend the upper voltage limit in the exploration of future candidate Mg-ion battery cathode materials, bismuth anodes have attracted considerable attention due to their efficient magnesiation and demagnesiation alloying reaction in such electrolytes. In this context, we present colloidal Bi nanocrystals (NCs) as a model anode material for the exploration of cathode materials for rechargeable Mg-ion batteries. Bi NCs demonstrate a stable capacity of 325 mAh g-1 over at least 150 cycles at a current density of 770 mA g(-1), which is among the most-stable performance of Mg-ion battery anode materials. First-principles crystal structure prediction methodologies and ex situ X-ray diffraction measurements reveal that the magnesiation of Bi NCs leads to the simultaneous formation of the low-temperature trigonal structure, aMg3Bi2, and the high-temperature cubic structure, beta-Mg3Bi2, which sheds insight into the high stability of this reversible alloying reaction. Furthermore, small-angle X-ray scattering measurements indicate that although the monodispersed, crystalline nature of the Bi NCs is indeed disturbed during the first discharge step, no notable morphological or structural changes occur in the following electrochemical cycles. The cost-effective and facile synthesis of colloidal Bi NCs and their remarkably high electrochemical stability upon magnesiation make them an excellent model anode material with which to accelerate progress in the field of Mg-ion secondary batteries.
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