Toyota Jidosha Kabushiki Kaisha

Hiroshi Kawadu

Hisataka Fujimaki

Hisanao Kojima

Shinya Kamada

Provided is a method for producing a lithium secondary battery in which localized precipitation of a foreign metal in the negative electrode can be reliably suppressed in a shorter time, regardless of, for instance, electrode type or electrode variability. The production method is a method for producing a secondary battery that includes a positive electrode provided with a positive electrode active material layer, a negative electrode provided with a negative electrode active material layer, and a nonaqueous electrolyte. The method comprises a step of constructing a cell including the positive electrode, the negative electrode and the nonaqueous electrolyte; a micro-charging step of performing charging over one hour or longer, up to 0.01% to 0.5% of the capacity of the constructed cell, in a state of charge such that a positive electrode potential is equal to or higher than an oxidation potential of iron (Fe), and a negative electrode potential is equal to or higher than a reduction potential of iron (Fe), and maintaining the state of charge; and a step of performing an initial conditioning charging.

Method for producing secondary battery

Provided are a secondary battery having a configuration with which localized metal contaminant precipitation at the negative electrode can be reliably inhibited in less time, and a method for producing a secondary battery that allows reliable deactivation of metal contaminant in less time. The battery comprises a positive electrode, a negative electrode, and a separator placed between the two electrodes. The separator has an air resistance Rp&#x2266;100 sec in an in-plane direction vertical to its thickness direction and an air resistance Rt&#x3e;Rp in the thickness direction. The method comprises a minimal charging step where the cell is charged to 0.01% to 0.5% capacity over at least one hour to obtain a state of charge where the positive and negative electrode potentials are at or above the oxidation and reduction potentials of a probable metal contaminant, respectively; and a step of performing initial conditioning charging.

Growing community of inventors

Toyota, Japan

Hiroshi Kawadu