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

• US 20050208368A1
• Filed: 05/18/2005
• 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 7,180,298 B2
• Time in Patent Office: Days
• US Class Current: 429/49
• 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 regenerating a secondary battery, characterized in that an electrolyte is only supplemented without performing a reducing treatment when the level of the degradation of a negative electrode is low, and a reducing agent is added to said electrolyte when the level of the degradation of said negative electrode is high.

2. A method as claimed in claim 1, wherein the level of the degradation of said negative electrode is judged low, and said electrolyte is only supplied when the average thickness of said oxidized layer which is formed on said surface of said active material of said negative electrode is less than a predetermined standard, and the level of the degradation of said negative electrode is judged high, and the reducing agent is added to the electrolyte when the average thickness of said oxidized layer is the predetermined standard or more.

3. A method as claimed in claim 2, wherein said standard is the average thickness of said oxidized layer, which is measured at the time the discharge capacity of a reference battery equivalent to the secondary battery rapidly decreases or the internal resistance of the reference battery rapidly increases.

4. A method as claimed in claim 3, wherein the average thickness of said oxidized layer as said standard is 1000 nm.

5. A method as claimed in claim 1, wherein said secondary battery is a nickel-hydrogen battery including a negative electrode of which a negative electrode active material is a hydrogen-occluding alloy, and an electrolyte interposed between a positive electrode and said negative electrode.