Method and device for judging the condition of secondary batteries and method for regenerating secondary batteries

• US 20050206389A1
• Filed: 05/16/2005
• Published: 09/22/2005
• Est. Priority Date: 08/10/1998
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ito, Takashi, Nakamura, Kenji, Minohara, Taketoshi
• Granted Patent: US 7,075,305 B2
• Time in Patent Office: Days
• US Class Current: 324/430
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/4242 Regeneration of electrolyte or reactants
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The internal resistance related value which is related to the internal resistance of a secondary battery is compared with a previously obtained relation between the internal resistance related value and battery condition to judge the battery condition of the secondary battery. Since the internal resistance related value is a value related to the internal resistance which closely depends on the battery condition, the battery condition can be judged in detail based on the above relation. And the internal resistance related value can be obtained more speedily with a predetermined method. On the other hand, when the level of the degradation of a negative electrode is low, an electrolyte is supplemented, and when the level of the degradation of the negative electrode is high, a reducing agent is added to the electrolyte to regenerate the secondary battery. With this regenerating method, the performance of the negative electrode can be recovered without degrading a positive electrode.

Claims

1. A method for judging the condition of a secondary battery by applying an AC voltage to the secondary battery to detect a quantity of electricity, which is related to an impedance of the secondary battery, or a quantity of electricity, which is related to the maximum power density, and judging the performance of the secondary battery based on the detected quantity of electricity, characterized in that a quantity of electricity related to the component of the impedance of the secondary battery, which does not vary with the frequency component of the AC voltage, is obtained as a DC impedance related quantity of electricity, and the quantity of electricity related to the component of the impedance of the secondary battery, which varies with the frequency component of the AC voltage, is obtained as an AC impedance related quantity of electricity, and the secondary battery is judged good when both said DC impedance related quantity of electricity and said AC impedance related quantity of electricity are respectively predetermined values or less while the secondary battery is judged inferior when both said DC impedance related quantity of electricity and said AC impedance related quantity of electricity are respectively more than predetermined values.

2. A method as claimed in claim 1, wherein by applying an AC voltage of a large number of frequency values within a predetermined frequency band to the secondary battery, a real axis component and imaginary axis component of said impedance of the secondary battery are obtained against each frequency value, and said quantity of electricity, which is related to the impedance, is calculated from the obtained real axis component and imaginary axis component.

3. A method as claimed in claim 1, wherein said AC impedance component is calculated based on a diameter of a circular arc-shaped locus of said impedance in a two-dimensional plane of which axes are said real axis component and said imaginary axis component.