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Issue 6, 2018
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Fluoroalkyl ether-diluted dimethyl carbonate-based electrolyte solutions for high-voltage operation of LiNi0.5Co0.2Mn0.3O2 electrodes in lithium ion batteries

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Abstract

The energy density of lithium-ion batteries can be increased by improving the battery voltage and/or specific capacity. However, conventional electrolyte solutions decompose oxidatively at high voltages. The stability against oxidation of electrolyte solutions could be enhanced by increasing the concentration of lithium salts. The nearly saturated 8.67 mol kg−1 LiBF4/dimethyl carbonate (DMC) electrolyte solution enabled high-voltage operation of LiNi0.5Co0.2Mn0.3O2 positive-electrodes at 4.6 V, and extended the discharge capacity to ca. 200 mA h g−1. BF4 anions, as well as DMC solvents, were stabilized at the high concentration. To reduce the viscosity and Li concentration without losing the high stability against oxidation toward practical use, the highly concentrated electrolyte solution was diluted with fluorinated co-solvents having a low donor ability. Raman spectroscopy revealed that the solvation structure of LiBF4/DMC was maintained after dilution with a specific fluoroalkyl ether. The resultant low-viscosity and -concentration electrolyte solution was highly stable against oxidation at the LiNi0.5Co0.2Mn0.3O2 electrodes as long as the DMC/LiBF4 molar ratio was kept low. The charge/discharge performance was much better than that for a conventional 1 M LiPF6/ethylene carbonate-based electrolyte solution and the energy density far exceeded that of 5 V class LiNi0.5Mn1.5O4 electrodes.

Graphical abstract: Fluoroalkyl ether-diluted dimethyl carbonate-based electrolyte solutions for high-voltage operation of LiNi0.5Co0.2Mn0.3O2 electrodes in lithium ion batteries

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Publication details

The article was received on 21 Jan 2018, accepted on 22 Mar 2018 and first published on 29 Mar 2018


Article type: Paper
DOI: 10.1039/C8SE00036K
Citation: Sustainable Energy Fuels, 2018,2, 1197-1205
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    Fluoroalkyl ether-diluted dimethyl carbonate-based electrolyte solutions for high-voltage operation of LiNi0.5Co0.2Mn0.3O2 electrodes in lithium ion batteries

    T. Doi, R. Matsumoto, Z. Cao, M. Haruta, M. Hashinokuchi and M. Inaba, Sustainable Energy Fuels, 2018, 2, 1197
    DOI: 10.1039/C8SE00036K

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