JPS6046516B2 - Overcharge detection method for sealed storage batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealed storage battery equipped with a hydrogen gas oxidation auxiliary electrode, and particularly to a method for detecting oxygen gas generated during overcharging.

Conventionally, sealed storage batteries such as nickel-zinc storage batteries and nickel-cadmium storage batteries generate a large amount of oxygen gas when overcharged, causing various problems such as increased internal pressure, expansion of the container, and failures due to electrolyte leakage. It was hot.

Conventionally, in order to eliminate such a problem, the following method is known as a method for detecting overcharging after charging is completed. (1) Battery voltage detection method, (2) Coulometer method to memorize the amount of energization, (3) Detection method using battery temperature rise or catalyst temperature rise, (4) Detection method using electrolyte specific gravity change 1 →μ1:}1 -Hon-μ, Ll1-, and O all had large detection errors and were not practically satisfactory. For example, in a battery voltage detection method that detects overcharging by detecting the terminal voltage of a storage battery at the end of charging, overcharging is detected because it is difficult to maintain a constant terminal voltage due to changes in battery internal resistance, temperature changes due to heat generation during charging, etc. was difficult. Another overcharge detection method is to detect overcharge by providing an oxygen gas absorption electrode in the battery and measuring the potential difference between the oxygen gas absorption electrode and the cathode. This method measures the oxygen gas generated during overcharging as an oxygen gas absorption current flowing between the oxygen gas absorption electrode and the cathode, but with this method, the oxygen gas absorption electrode itself is easily oxidized and deteriorates. Resulting in. This resulted in a disadvantage that the sensitivity deteriorated and the overcharge detection accuracy deteriorated. In view of the above points, it is an object of the present invention to provide a method for detecting overcharge of a sealed storage battery that responds accurately without being affected by environmental temperature, charging current, etc.

The present invention comprises an anode, a cathode, a separator interposed between the anode and the cathode, a waterproofed hydrogen gas oxidation auxiliary electrode, a diode and a resistor connected in series between the anode and the hydrogen gas oxidation auxiliary electrode. There is a method for detecting overcharge of a sealed storage battery in which oxygen gas generated during overcharging is detected by a voltage change between an anode and a hydrogen gas oxidation auxiliary electrode.

An example of the configuration of a sealed storage battery suitable for use in the method of the present invention will be described below with reference to FIG. 1, which shows a cross-sectional view.

The sealed storage battery has a power generation section configured as follows. However, in the power generation section of the lever, a sintered anode layer 1 mainly composed of a nickel compound and a cathode layer 2 mainly composed of a zinc compound are laminated with a separator (including an electrolyte holding layer) 3 interposed therebetween. It is constructed by winding it into a spiral shape. This power generation section has a metal container 7 which also serves as a cathode terminal and has an open end.
A heat-shrinkable tube 9 having electrical insulation is interposed therebetween. 4 indicates the anode lead, 5 indicates the cathode lead,
The anode lead 4 is connected to a lid 6 which also serves as an anode terminal, and the cathode lead 5 and a metal container 7 which also serves as a cathode terminal. The lid 6 which also serves as an anode terminal is sealed and attached to the opening of the metal container 7 which serves as a cathode terminal via an electrical insulating material 8. Further, a waterproofed hydrogen gas oxidation auxiliary electrode 10 is provided in the air core with a separator 3 in between, and a resistor 11 and a silicon diode 12 are connected in series between the hydrogen gas oxidation auxiliary electrode 10 and the anode 1. The auxiliary electrode lead 13 is connected to an auxiliary electrode terminal 14 provided on the lid 6 which also serves as an anode terminal via an electrolyte-resistant insulating resin layer. In the above configuration, the hydrogen gas oxidation auxiliary electrode is polarized in the base direction during charging, and the hydrogen gas generated by charging and discharging and self-discharge is electrochemically oxidized and the hydrogen absorption current (H2 + 20H
-→2H20+? flows. However, during overcharging, the hydrogen absorption current decreases rapidly at the same time as oxygen gas is generated, and the hydrogen gas oxidation auxiliary electrode sharply decreases with respect to the anode potential. It is polarized in the noble direction, and the voltage between the anode and the hydrogen gas oxidation auxiliary electrode decreases rapidly. Note that when charging is interrupted, most of the oxygen gas is absorbed by the cathode, and the potential of the hydrogen gas oxidation auxiliary electrode rapidly recovers. Therefore, by measuring and determining the voltage between the anode and the hydrogen gas oxidation auxiliary electrode, a sudden voltage drop due to oxygen gas generation during overcharging can be detected.

In order to measure the voltage between the anode and the cathode and the voltage between the anode and the hydrogen gas oxidation auxiliary electrode, voltage recorders 15 and 16 are provided, for example, as shown in FIG. 1. 17 is for charging the storage battery.
The figure shows the power supply section for the power supply. Specific examples to which the method of the present invention is applied will be shown below.

As a sealed storage battery, an AA nickel-zinc storage battery having an anode charging capacity of 1.5 Ah and a cathode charging capacity of 4.5 Ah was constructed as described above. A porous nickel sintered body with an apparent surface area of 5C71f1 and a thickness of 0.3W1 was used as a hydrogen gas oxidation auxiliary electrode, impregnated with a mixture of platinum and tungsten carbide as a hydrogen gas absorption catalyst, and polytetrafluoroethylene was used for waterproofing. The one that was bound was used. Further, the resistor 11 is 100Ω, the diode 12 is a silicon diode, and each is coated with an electrolyte-resistant resin. As the electrolytic solution, an 8N potassium hydroxide aqueous solution saturated with zinc oxide was used. Figure 2 shows the anode-cathode terminal voltage (hereinafter abbreviated as El), the anode-auxiliary electrode terminal voltage (hereinafter abbreviated as El3), and the anode-cathode terminal voltage (hereinafter abbreviated as El) and Indicates changes in battery internal pressure. In the curve a of FIG. 2, A1 to A2 indicate charging of the battery active material, and voltage increases in A2 to A3 indicate progress during overcharging. Then, at A3, most of the charging current is used to generate oxygen gas, and at this time, the generation of oxygen gas from the anode rapidly increases, and the pressure inside the cell increases as shown by curve c. E
In curve b showing l3, a rapid voltage drop is seen from 8 onwards. This is because the potential of the hydrogen gas oxidation auxiliary electrode is polarized in the noble direction at the same time as oxygen gas is generated. In Naori 4, most of the oxygen gas is absorbed by the cathode, and El3 rapidly recovers again. Next, El when changing the environmental temperature. and El3 were measured and shown in FIG. As a result, El during overcharging. The change in is significantly affected by the environmental temperature, and the higher the temperature, the smaller the change becomes, making it difficult to detect overcharging.
However, the rate of change of El3 is not affected by changes in environmental temperature and always shows a rapid change (voltage drop), making it possible to accurately detect overcharge. Further, FIG. 4 shows El2 and El3 when the charging current is changed, and FIG. 5 shows El2 and El3 when the number of charging and discharging cycles changes.

As a result, El2 is significantly affected by a decrease in battery capacity due to changes in charging current and the number of charge/discharge cycles, an increase in internal resistance, etc., making it difficult to detect overcharging. On the other hand, El3 exhibits a rapid change (voltage drop) during overcharging, making it possible to reliably detect overcharging. As described above, El at the end of charging.

Changes in battery life are affected by environmental temperature, charging current, and number of charge/discharge cycles, making it difficult to detect overcharging. On the other hand, by using the method of the present invention and measuring El3, it is possible to measure El3 without being affected by the above conditions, and to measure El3 due to oxygen gas generation at the end of charging.
It shows a significant voltage drop of 3, and can easily be overcharged.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a configuration example of an overcharging device for a sealed storage battery according to the present invention, and FIGS. 2 to 5! ? 1 is a curve diagram showing various characteristics of a method and device for detecting overcharge of a sealed storage battery according to the present invention. 1... Anode layer, 2... Cathode layer, 3...
Separator, 6... Lid body that also serves as an anode terminal, 7... Metal container that also serves as a cathode terminal, 10...
...Hydrogen gas oxidation auxiliary electrode, 11...Resistor, 1
2... Diode, 13... Auxiliary pole lead, 14... Auxiliary pole terminal.

Claims (1)

[Claims] 1 an anode, a cathode, a separator interposed between the anode and the cathode, a waterproofed hydrogen gas oxidation auxiliary electrode, a diode and a resistor connected in series between the anode and the hydrogen gas oxidation auxiliary electrode; A sealed storage battery characterized by detecting oxygen gas generated during overcharging by a voltage change between an anode and a hydrogen gas oxidation auxiliary electrode. Overcharge detection method.