• 18 MAY 16
    LiODFB

    LiODFB

    Application

    LiODFB (Lithium oxalyldifluoroborate) is first reported as the salt for improved electrolyte of Li-ion battery. This salt was found to have the combined advantages of lithium bis(oxalato)borate (LiBOB) and LiBF4 due to its chemical structure comprising the half molecular moieties of LiBOB and LiBF4. Compared with LiBOB, the salt is more soluble in linear carbonates and the resulting solution is less viscous, which results in the battery better low temperature and high rate performance. Unlike LiBF4, the salt is highly capable of stabilizing solid electrolyte interface (SEI) on the surface of graphite anode, which enables Li-ion cell to be operated stably at high temperature. For example, a graphite/LiNi1−x− yMxNyO2 (M and N are metal atoms) Li-ion cell suffered only about 10% capacity loss after 200 cycles at 60 °C. On the other hand, graphite can be cycled reversibly with LiODFB even in a solution containing high concentration (50 wt%) of propylene carbonate (PC), which makes it possible to formulate the low freezing temperature electrolyte by using PC as the co-solvent. Other merits of the LiODFB-based electrolytes include (1) the ability to support metallic lithium cycling reversibly on the surface of copper anode current collector, (2) the ability to passivate aluminum cathode current collector at high potentials, (3) the ability to participate in formation of the SEI and support Li-ion battery operating stably at high temperatures, and (4) the ability to increase battery safety protection and overcharge tolerance.

    Features

    1. LiODFB has higher thermal stability and much less free acid content, and released CO2 possibly provides good safety of cells.

    2. The cells using LiODFB-based electrolyte have lower capacity fade than the cells using LiPF6-based electrolyte after 100 cycles at 55 ℃, and higher initial capacity retention at the elevated temperature.

    3. At 0.5C and 1C discharge rates, the rate capability of the cells with the LiODFB-based electrolyte is almost the same as that of the cells with the LiPF6-based electrolyte after 20 cycles,and the gap between the two cells is tiny.

    4. Interface properties of the cells show that LiODFB is reduced and forms a thickening and protective SEI film on the negative electrode. Although this can increase the impedance of SEI film, the cells still can provide a preferable rate performance. More work is needed to carry out in the lithium battery of commercialization in the future.

    Synonyms Lithium Oxalyldifluoro Borate; Borate(1-), [ethanedioato(2-)-κO1,κO2]difluoro-, lithium (1:1); Lithium [ethanedioato(2-)-κ2O1,O2](difluoro)borate(1-); Lithium difluoro(oxalato)borate; LITHIUM DIFLUORO(OXALATO)BORATE(1-)

    CAS Number 409071-16-5 | Molecular Formula C2BF2LiO4 | Molecular Weight 143.768 | MDL Number MFCD21608640

    SMILES [Li+].[B-]1(OC(=O)C(=O)O1)(F)F

    StdInChI InChI=1S/C2BF2O4.Li/c4-3(5)8-1(6)2(7)9-3;/q-1;+1

    StdInChIKey MEDDCIKGDMDORY-UHFFFAOYSA-N

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