JP2013145664A - Control valve type lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control valve type lead storage battery which has high capacity and excellent various properties and is arranged so that an internal short circuit never occurs even if the distance between electrodes is shortened.SOLUTION: The control valve type lead storage battery comprises an electrode plate group having positive and negative electrodes opposed to each other with a separator located therebetween. The content of tin contained in an active material of the positive electrode is 0.2-0.5 mass% to the total amount of lead in the active material. The distance between the positive and negative electrodes is 0.3-0.45 mm.

Description

  The present invention relates to a technique for improving discharge characteristics and cycle life characteristics of a control valve type lead-acid battery.

  In recent years, as a countermeasure for global environmental problems, a shift from an engine vehicle using fossil fuel to a clean electric vehicle that does not exhaust exhaust gas such as carbon dioxide has been accelerated. On the other hand, a storage battery used for energy storage combined with natural energy such as a solar battery has attracted attention. Accordingly, there is a demand for utilization of lead-acid batteries that have been used for a long time and have high reliability as power sources and to improve their performance (particularly, increase in capacity and increase in life).

  Control valve-type lead-acid batteries that do not require maintenance meet the above-mentioned requirements, but the design is adapted to trickle applications that continue to be charged with a weak current, and the design is adapted to those that are suitable for cycle applications involving relatively deep discharge (cycles). It is necessary to achieve a long service life in the application). For this purpose, it is particularly necessary to improve the positive electrode.

  In the positive electrode, as the charge / discharge cycle is repeated, the active material softens and easily falls off the lattice. Since this problem can be overcome if a tin compound is added to the positive electrode, efforts have been made to devise the amount and form of addition as in Patent Documents 1 to 3.

JP 05-013081 A Japanese Patent Laid-Open No. 05-054881 Japanese Patent Laid-Open No. 06-0776825

  In order to increase the battery capacity per volume in accordance with the above-described requirements, a control valve type lead storage battery in which the distance between the positive electrode and the negative electrode (distance between the electrodes) is shortened is being demanded. However, in accordance with the description in Patent Documents 1 to 3 (with tin contained in a range of 0.01 to 5 mol% with respect to the amount of lead in the positive electrode active material), a control valve type lead-acid battery with a short interelectrode distance is randomized. In the case of manufacturing in this manner, the problem is that internal short-circuits frequently occur.

  An object of the present invention is to provide a control valve type lead-acid battery that has a high capacity and excellent characteristics without causing an internal short circuit even when the distance between the electrodes is shortened. To do.

  In order to solve the above-described problem, the invention according to claim 1 of the present invention is a control valve type lead-acid battery having an electrode plate group in which a positive electrode and a negative electrode are opposed to each other via a separator. The content of tin contained in the material is 0.2 to 0.5% by mass with respect to the total amount of lead in the active material, and the distance between the positive electrode and the negative electrode is 0.3 to 0.45 mm. It is characterized by being.

  The invention according to claim 2 of the present invention is the separator according to claim 1, wherein the separator comprises a first separator made of a glass mat and a bag-like second separator including at least one of a positive electrode and a negative electrode. It is characterized by that.

  The internal short circuit that becomes a problem occurs when the tin compound added to the active material of the positive electrode elutes, forms a dendrite when energized, and connects the positive electrode and the negative electrode. This internal short circuit is accelerated not only when the tin compound is unevenly distributed but also when the distance between the electrodes is short.

  Further, when the distance between the electrodes is extremely shortened, the amount of the electrolyte solution held between the electrodes is reduced, so that various characteristics of the battery are deteriorated.

  However, as a result of intensive studies by the present inventors to reduce the tin compound that is the source of dendrite while shortening the distance between the electrodes, in a very limited specific range, not only the generation of dendrite can be suppressed, but also the battery We found that the properties improved in a well-balanced manner. The specific range is that the content of tin contained in the active material of the positive electrode is 0.2 to 0.5% by mass with respect to the total amount of lead in the active material, and the distance between the electrodes is 0.3 to The range is 0.45 mm. The present invention makes use of this finding.

  ADVANTAGE OF THE INVENTION According to this invention, even if it shortens distance between electrodes and aims at high capacity | capacitance, it becomes possible to provide a control valve type lead acid battery excellent in various characteristics, without causing an internal short circuit.

The schematic diagram which shows the electrode group of the control valve type lead acid battery of this invention The figure which shows the evaluation result of the Example of this invention The figure which shows the evaluation result of the Example of this invention

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an electrode plate group of a control valve type lead storage battery of the present invention. An electrode plate group 4 is formed by opposing a positive electrode 1 in which an active material made of lead dioxide or the like is held in a lattice and a negative electrode 2 in which an active material made of lead or the like is held in a lattice through a separator 3. To do. The separator 3 includes a plate-like first separator 3 a made of a glass mat and a bag-like second separator 3 b including the positive electrode 1.

  In the present invention, the content of tin contained in the active material of the positive electrode 1 is 0.2 to 0.5% by mass with respect to the total amount of lead in the active material, and the electrodes of the positive electrode 1 and the negative electrode 2 The inter-distance (the sum of the thickness of the first separator 3a and the thickness of the second separator 3b) is 0.3 to 0.45 mm.

  The internal short circuit which the present invention regards as a problem occurs when the tin compound added to the active material of the positive electrode 1 is eluted and dendrites are formed during energization to connect the positive electrode 1 and the negative electrode 2 together. This internal short circuit is accelerated not only when the tin compound is unevenly distributed but also when the distance between the electrodes is short. Further, when the distance between the electrodes is extremely shortened, the amount of the electrolyte solution held between the electrodes is reduced, so that various characteristics of the battery are deteriorated.

  However, as a result of diligent investigations to reduce the tin compound that is the source of dendrites while shortening the distance between the electrodes, it is possible not only to suppress the generation of dendrites in a very limited specific range, but also to have a good balance of battery characteristics. I found out that The specific range is that the content of tin contained in the active material of the positive electrode 1 is 0.2 to 0.5 mass% with respect to the total amount of lead in the active material, and the distance between the electrodes is 0.3. It is the range of -0.45 mm.

  When the tin content is less than 0.2% by mass, the tin compound as a conductor cannot be efficiently present around the active material, so that the initial charging efficiency is deteriorated and the initial capacity is lowered. On the other hand, when the tin content exceeds 0.5% by mass, an internal short circuit due to dendrites is likely to be induced in an environment where the distance between the electrodes is short.

  When the distance between the electrodes is less than 0.3 mm, the electrolyte solution held between the electrodes (held by the first separator 3a and the second separator 3b) is reduced, and various characteristics (such as initial characteristics) of the battery are deteriorated. In addition, even if the tin content is reduced, the distance between the electrodes is extremely short, so that an internal short circuit due to dendrites tends to be induced. On the other hand, if the distance between the poles exceeds 0.45 mm, the concept of the present invention “desired to increase the capacity by shortening the distance between the poles” deviates from the concept.

  Here, the separator 3 is mainly composed of a first separator 3a made of a glass mat that plays a role of holding an electrolytic solution, and a polymer material (e.g., polypropylene that has been subjected to a hydrophilic treatment) that plays a role of mainly preventing an internal short circuit. By comprising from the 2nd separator 3b using the nonwoven fabric which becomes, the effect of this invention becomes easy to be acquired.

  When the second separator 3b includes the positive electrode 1 as shown in FIG. 1, even if the active material of the positive electrode 1 falls off, it is stored in the bag-like second separator 3b (so as not to contact the negative electrode 2). In addition, rationalization can be achieved by considering the constituent conditions of the electrode plate group 4 (constituted by one more negative electrode 2 than the positive electrode 1). On the other hand, when the second separator 3b includes the negative electrode 2, since the second separator 3b is disposed on the outermost side of the electrode plate group 4, it can be smoothly inserted into a battery case or the like. Occurrence can be avoided.

A predetermined amount of lead powder is kneaded while adding dropwise an aqueous solution of SnSO ₄ and dilute sulfuric acid in an amount of 0.1 to 0.7% by mass of tin with respect to the total amount of lead (one condition is an aqueous solution of SnSO _4). After filling the lattice, aging and drying steps were performed to obtain an unformed positive electrode 1. Further, by going through the method described above without using the SnSO ₄ aqueous solution, to obtain a negative electrode 2 of the unformed.

  The positive electrode 1 is included in the second separator 3b using a nonwoven fabric made of polypropylene that has been subjected to hydrophilic treatment in the form of a bag, and this is opposed to the negative electrode 2 via the first separator 3a made of glass mat. Board group 4 was constructed. Here, the sum of the thickness of the first separator 3a and the thickness of the second separator 3b was 0.37 mm. After this electrode plate group 4 was put in a container, it was injected as an electrolytic solution made of a predetermined amount of sulfuric acid and subjected to initial charging, thereby producing a single cell battery having a nominal capacity of 60 Ah at a 5-hour rate. The following evaluation was performed with respect to the single cell produced on various conditions.

(Initial capacity)
One cycle when a charge of 0.50 Ah / g is charged based on the weight of all lead elements in the active material of the positive electrode and then discharged to 1.65 V at a constant current of 3 hours in a 25 ° C. atmosphere. The eye discharge capacity was evaluated as the initial capacity.

(Internal short circuit)
Twenty batteries were prepared for each production condition, the voltage was measured after charging until the SOC reached 100% in an atmosphere at 25 ° C., stored in a constant temperature room at 25 ° C. for 2 weeks, and then the voltage of the battery again. Was measured. The amount of voltage decrease obtained as a difference is due to self-discharge or self-discharge and short-circuit discharge. When the amount of voltage decrease is 7 mV or more, it was determined that an internal short circuit occurred.

  The evaluation results are shown in FIG. As is clear from FIG. 2, when the tin content is less than 0.2% by mass, the tin compound as the conductor cannot be efficiently present around the active material, so that the initial charging efficiency is deteriorated and the initial capacity is reduced. Lower. On the other hand, when the content of tin exceeds 0.5% by mass, an internal short circuit occurs. As a result of disassembling the battery that caused the internal short circuit, all these were due to tin dendrites. It can be seen that when a tin compound similar to the conventional one is added in an environment where the distance between the electrodes is as short as 0.37 mm as in this example, an internal short circuit due to tin dendrite tends to be induced. From FIG. 2, the appropriate range of the tin content in an environment where the distance between the electrodes is as short as 0.37 mm is 0.2 to 0.5 mass% with respect to the total amount of lead contained in the active material of the positive electrode. I know that there is.

The content of SnSO ₄ with respect to the positive electrode was kept constant at 0.35% by mass with respect to the total amount of lead contained in the active material of the positive electrode, and the distance between the electrodes was changed between 0.1 and 0.6 mm. Except for this, a single cell battery was produced under the same configuration conditions as in Example 1, and evaluated under the same evaluation conditions as in Example 1. The evaluation results are shown in FIG.

  When the distance between the electrodes is less than 0.3 mm, an internal short circuit occurs. As a result of disassembling the battery that caused the internal short circuit, all these were due to tin dendrites. In addition, the initial characteristics of the battery also deteriorated. This is considered to be due to the fact that the electrolyte solution held between the electrodes (held by the first separator 3a and the second separator 3b) is reduced. On the other hand, when the distance between the electrodes exceeds 0.45 mm, the initial capacity of the battery is reduced because it deviates from the concept of “increasing the capacity by shortening the distance between the electrodes” intended by the present invention. From FIG. 3, it can be seen that the appropriate range of the distance between the electrodes is 0.3 to 0.45 mm when the distance between the electrodes is shortened and a high capacity type control valve type lead-acid battery is adopted.

  By using the present invention, it is possible to provide a control valve type lead-acid battery having a high capacity and excellent characteristics. Its industrial applicability is extremely high.

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 3a 1st separator 3b 2nd separator 4 Electrode plate group

Claims (2)

A control valve type lead-acid battery having an electrode plate group in which a positive electrode and a negative electrode are opposed via a separator,
The content of tin contained in the active material of the positive electrode is 0.2 to 0.5% by mass with respect to the total amount of lead in the active material, and the distance between the positive electrode and the negative electrode is 0 A control valve-type lead-acid battery characterized by having a diameter of 3 to 0.45 mm. 2. The control according to claim 1, wherein the separator includes a first separator 3 a made of a glass mat and a bag-like second separator 3 b including at least one of the positive electrode and the negative electrode. Valve-type lead acid battery.

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