Patent ID: 8617742

Claim:
A method for manufacturing a lithium ion secondary cell, comprising: (a) a step of preparing a positive electrode, a negative electrode, a separator, and an initial electrolyte serving as constituent members of the cell, wherein the initial electrolyte includes, a fluorine-containing lithium salt as a supporting salt being dissolved in an organic solvent in a prescribed concentration; (b) a step of ascertaining, based on the content of moisture contained in the positive electrode, the negative electrode, the separator, and the initial electrolyte prepared in the step (a), a molar equivalent value a of the total content of moisture to be mixed in a case due to the constituent members; (c) a step of substituting a value of the Î± into the following mathematical expression (A): [Mathematical Expression 2] âˆ’0.8â‰¦log(Î²/Î±)â‰¦1.5â€ƒâ€ƒ(A), and calculating a numerical value range of the Î² satisfying the mathematical expression (A); (d) a step of adding a compound represented by the following chemical formula (I): as an additive, in a number of moles within the numerical value range of Î² calculated in the step (c) to the initial electrolyte, and preparing a final electrolyte; and (e) a step of assembling a lithium ion secondary cell under an environment with a dew point of âˆ’10Â° C. or less using the positive electrode, the negative electrode, the separator, and the final electrolyte.