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Method for producing secondary battery

  • US 9,157,964 B2
  • Filed: 09/24/2009
  • Issued: 10/13/2015
  • Est. Priority Date: 09/24/2009
  • Status: Active Grant
First Claim
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1. A method for producing a secondary battery, comprising:

  • an inspection step for selecting the secondary battery having a defect caused by a micro short-circuit among a plurality of the secondary batteries,wherein the inspection step includes a first step for performing a self-discharge inspection in which the plurality of the secondary batteries are allowed to stand at normal temperature for a predetermined period, a second step for calculating a short circuit resistance of said each secondary battery, and a third step for determining the defect caused by the micro short-circuit on the basis of the short circuit resistance in said each secondary battery,wherein in the second step, the short circuit resistance Rs is calculated from a formula Rs=t/C·

    In{Vs1·

    Vi0/(Vs0·

    Vi1)} by using a capacitance C of said each secondary battery calculated before the self-discharge inspection, a time t required for the self-discharge inspection, a first reference voltage Vi0 calculated from open circuit voltages of the plurality of the secondary batteries measured before the self-discharge inspection, a second reference voltage Vi1 calculated from the open circuit voltages of the plurality of the secondary batteries measured after the self-discharge inspection, a first voltage Vs0 which is the open circuit voltage, measured before the self-discharge inspection, of one secondary battery selected from the plurality of the secondary batteries, and a second voltage Vs1 which is the open circuit voltage of the selected secondary battery measured after the self-discharge inspection,wherein in the third step, if the short circuit resistance is equal to or lower than a predetermined standard value, the selected secondary battery is determined to have the defect caused by the micro short-circuit,wherein the first reference voltage is a smaller value of an average and a median of the open circuit voltages of the plurality of the secondary batteries measured before the self-discharge inspection, andwherein the second reference voltage is a larger value of an average and a median of the open circuit voltages of the plurality of the secondary batteries measured after the self-discharge inspection.

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