Non-aqueous electrolytic solution for lithium secondary battery or lithium ion capacitor, and lithium secondary battery or lithium ion capacitor using the same
摘要
說明書
Therefore, the present inventors made a diligent study in order to solve the above-described problems, and consequently have discovered that the flash point of the non-aqueous electrolytic solution is allowed to be 20° C. or higher and the electric conductivity of the non-aqueous electrolytic solution is allowed to be 8 mS/cm or more under the conditions that in a non-aqueous electrolytic solution including a lithium salt as dissolved in a non-aqueous solvent in a concentration of 0.8 to 1.5 M (mol/L), the non-aqueous solvent includes, in relation to the whole of the non-aqueous solvent, 5 to 25% by volume of ethylene carbonate, 5 to 25% by volume of propylene carbonate, 20 to 30% by volume of dimethyl carbonate, 10 to 20% by volume of a fluorinated chain ester, and 20 to 40% by volume of methyl ethyl carbonate, the total content of ethylene carbonate and propylene carbonate in the non-aqueous solvent is 20 to 30% by volume, and the total content of dimethyl carbonate and the fluorinated chain ester in the non-aqueous solvent is 30 to 40% by volume. The present inventors have perfected the present invention by discovering that furthermore, by using a mixed solvent containing various carbonates and the fluorinated chain ester in specific proportions, the resulting non-aqueous electrolytic solution does not freeze even at ?40° C. or lower, is capable of being used with a liquid state being maintained in “a wide temperature range extending over a temperature width of 100° C.,” exhibits excellent battery performances, and the withstand voltage is also improved. It is to be noted that such effects as described above are the effects that were absolutely not able to be achieved by the techniques of Patent Documents 1 to 5, and are the effects that have not absolutely been suggested in Patent Documents 1 to 5.
