JP4904674B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead-acid battery.

  Lead-acid batteries are used for various purposes such as vehicle engine starting and backup power supply. Among them, the lead acid battery for starting supplies power to various electric / electronic devices mounted on the vehicle as well as supplying power to the cell motor for starting the engine. After the engine is started, the lead storage battery is charged by an alternator. Here, the output voltage and output current of the alternator are set so that charging and discharging of the lead storage battery are balanced and the SOC (charged state) of the lead storage battery is maintained at 90 to 100%.

  In recent years, improvement in fuel efficiency of vehicles has been studied from the viewpoint of environmental conservation. For example, idle-stop cars that stop the engine while the vehicle is temporarily stopped, and regenerative braking systems that convert the vehicle's kinetic energy into electrical energy and store this electrical energy are put into practical use. ing.

  In the idling stop vehicle as described above, the lead storage battery is not charged while the engine is stopped. On the other hand, it is necessary to continue to supply power to the on-board equipment, which inevitably increases the depth of discharge. In addition, in a vehicle equipped with a regenerative braking system, it is necessary to control the SOC of the lead storage battery to about 50 to 90%, which is lower than before, in order to store electric energy during regeneration.

  Therefore, in a vehicle equipped with these systems, the lead storage battery is used at a deeper discharge depth and lower SOC, and for application to such a vehicle, the lead storage battery is used when a deep discharge is performed. Life characteristics are required. The main causes of deterioration of the lead-acid battery in such a deep discharge life are deterioration of the positive electrode active material caused by a decrease in charge acceptability of the negative electrode active material due to deep discharge and insufficient charge of the positive electrode generated thereby.

In order to suppress the deterioration of the positive electrode due to the deep discharge of the lead storage battery, for example, Patent Document 1 discloses that a lead alloy layer containing tin and antimony is formed on the surface of the positive electrode lattice of a lead-calcium-tin alloy. . Tin and antimony present on the surface of the positive electrode lattice have an effect of suppressing deterioration of the active material and formation of a high resistance layer at the active material-lattice interface. Such a configuration as disclosed in Patent Document 1 is very effective in a start-up lead-acid battery used in a charged state in which the conventional SOC exceeds 90%, and dramatically improves the life characteristics. .
JP-A-3-37962

  However, if the vehicle is equipped with an idle stop vehicle or a regenerative braking system as described above, that is, when the discharge depth is deeper and the SOC is lower, the configuration as in Patent Document 1 is only used. In the case of a battery, the life characteristics were not sufficient.

Such a deterioration phenomenon of the deep discharge life is not so remarkable in a control valve type lead-acid battery which does not have a free electrolytic solution released from the electrode plate group by impregnating the electrode plate group with all the electrolyte solution. . In such a valve-regulated lead-acid battery, a charging current is generated due to a gas absorption reaction inside the battery. Therefore, even if the above-described decrease in the charge acceptability of the negative electrode proceeds, the decrease in the amount of charge in the positive electrode is not much. Not serious. However, in an open-type liquid lead-acid battery in which all electrode plates are immersed in an electrolyte, a gas absorption reaction does not occur, so a charging current based on the gas absorption reaction cannot be expected, and a negative charge acceptability decrease immediately occurs. Directly connected to a decrease in charging current, it was more difficult to secure the amount of charge electricity at the positive electrode.
And the lead sulfate which is a discharge product accumulates on a positive electrode by the fall of the amount of charge electricity. The lead sulfate accumulated in the positive electrode is less likely to recover by charging than the lead sulfate accumulated in the negative electrode. Further, when insufficient charging at the positive electrode is repeatedly performed, the capacity of the positive electrode rapidly decreases at a certain point. In the positive electrode in which a sudden capacity drop has occurred, the bonding between the positive electrode active materials is impaired, and recovery becomes more difficult even after charging. Therefore, in order to suppress the capacity decrease due to insufficient charging of the positive electrode, it is necessary to maintain the charge acceptability of the negative electrode and to secure the amount of charge electricity.
In order to ensure charge acceptability of the negative electrode, a metal having a hydrogen overvoltage lower than Pb, such as Sb, can be added to the negative electrode. Thereby, since the negative electrode potential at the time of charging shifts more preciously, the charging voltage of the storage battery decreases. Therefore, the charging current at the time of constant voltage charging generally used in a lead storage battery increases, and deterioration due to insufficient charging at the positive electrode can be suppressed.

  However, although the addition of Sb in the negative electrode improves the charge acceptability, the negative electrode active material is promoted in the process of repeating the charge / discharge cycle, and the new active material has a new problem that the positive electrode and the negative electrode are short-circuited. Occurred. This falling off phenomenon of the negative electrode active material was remarkable particularly in an expanded lattice body having no frame around the negative electrode lattice as shown in FIG. In the case of a cast lattice body as shown in FIG. 3, it is a common practice to form the entire periphery of the negative electrode lattice body with a frame bone, but the cast lattice body is more productive than the expanded lattice body. There was the subject that it was low and was unpreferable at the surface of manufacturing cost reduction of a storage battery.

  It is an object of the present invention to provide a lead storage battery suitable for an idle stop vehicle, a vehicle equipped with a regenerative brake system, or the like that has drastically improved the deep discharge life characteristics by improving the charge acceptance in the negative electrode as described above. In particular, an object of the present invention is to provide such a lead storage battery at a lower cost by making it possible to apply an expanded lattice to the negative electrode lattice.

In order to achieve the above object, a lead storage battery according to the present invention is used in an idle stop vehicle or a vehicle equipped with a regenerative brake system, and comprises a positive electrode / negative electrode plate comprising a positive electrode grid and a negative electrode grid not containing Sb, and the negative electrode And a bag-like mat separator for covering the plate, the entire electrode plate surface of the positive electrode / negative electrode plate is immersed in an electrolyte solution, an expanded lattice is used as the negative electrode lattice, and only 1b of Sb is contained in the active material of the negative electrode. It is characterized by containing -30 ppm.

  As a result, by improving the charge acceptability at the negative electrode in the charge / discharge cycle of the lead storage battery in the lead storage battery for automobiles that is frequently used in the low SOC region, such as used in idle stop cars and cars equipped with a regenerative brake system, etc. In addition, it is possible to provide a lead-acid battery suitable for an idle stop vehicle, a vehicle equipped with a regenerative brake system, or the like that has drastically improved deep discharge life characteristics.

  Preferably, when the Sb contained in the negative electrode active material is 1 to 10 ppm, a more preferable lead storage battery can be provided.

  According to the present invention, by improving the charge acceptance in the negative electrode in the charge / discharge cycle of the lead-acid battery, the deterioration due to insufficient charging of not only the negative electrode but also the positive electrode is suppressed, and thus the effect of remarkably improving the life characteristics is obtained. It is very useful in industry.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The positive grid used in the lead storage battery of the present invention is made of a lead alloy substantially free of Sb. As a lead alloy not containing Sb, a Pb—Ca—Sn alloy is used in terms of strength and corrosion resistance. The amount of Ca in the positive electrode lattice is 0.03 to 0.10% by mass from the viewpoint of lattice strength, and the amount of Sn is 0.60 to 1.80% by mass from the viewpoint of lattice strength and corrosion resistance. Is appropriate.

  In the present invention, the fact that the positive electrode lattice does not substantially contain Sb means 0.002 mass% or less. Even if this amount of Sb is included in the positive electrode grid, it does not migrate to the negative electrode, and as a result, it affects the battery's maintenance-free performance such as the amount of self-discharge in the negative electrode and the reduction of the electrolyte. Absent.

  In addition, as a method of creating a lattice, a conventionally known cast lattice, continuous cast lattice, or a lattice body obtained by subjecting a rolled body of the lead alloy to punching or expanding can be used.

  In consideration of durability against overdischarge of the positive electrode, a Pb—Sn alloy layer containing about 2.0 to 7.0% by mass of Sn on a part of the positive electrode lattice surface and 1.0 to 7.0 wt% of Pb. A -Sb alloy layer can also be formed. It is of course possible to form a Pb—Sb—Sn alloy layer containing Sn and Sb at the concentrations described above.

  After filling the positive electrode grid with the positive electrode active material paste, the positive electrode plate in an unformed state is obtained by aging and drying. As known in the art, the positive electrode active material paste can be obtained by kneading lead powder containing lead oxide and metal lead as components with water and dilute sulfuric acid.

  Next, the negative electrode lattice is made of a lead alloy substantially free of Sb as a base material alloy, like the positive electrode lattice. As with the positive electrode lattice, a Pb—Ca—Sn alloy can be used. However, since the negative electrode lattice is not affected by corrosion as compared with the positive electrode, the addition of Sn is not always necessary. However, Sn, as described above, may improve the lattice strength or improve the molten lead flowability of the molten lead at the time of forming the cast lattice, so it may be added in an amount of about 0.2% to 0.6% by mass.

The amount of Ca in the negative electrode lattice is 0.03 to 0.10% by mass for the main purpose of securing the lattice strength, as in the positive electrode. Note that the presence of Sb in the negative electrode lattice directly affects the self-discharge of the negative electrode and the reduction of the electrolyte solution, so the content is made 0.001% by mass or less. Further, Fukyokukaku child is by the same method as the positive electrode grid, it is preferable to use a Rue Kisupando grid can be obtained.

  The negative electrode grid obtained as described above is filled with a negative electrode active material paste and aged and dried to prepare an unformed negative electrode plate.

  In this invention, 1-30 ppm of Sb is contained in the negative electrode active material after chemical conversion. As a method for adding Sb in the negative electrode active material, it can be added as an antimony compound such as antimony oxide or its salt such as antimony sulfate or antimonate during kneading of the negative electrode active material paste. In addition, as another method, it is also an extremely effective method to deposit Sb on the negative electrode active material by adding the above-described antimony compound to the dilute sulfuric acid electrolyte before the chemical charging step and performing chemical charging. It is. When Sb is added to the electrolytic solution, about 10 ppm of Sb remains in the electrolytic solution.

This negative electrode plate is accommodated in a bag-shaped separator, and these and the positive electrode plate are combined to constitute an electrode plate group. Incidentally, as a separator material, it is possible to use a mat formed of acid resistant fibers such as glass fibers or polypropylene fibers. In the negative electrode active more purpose of suppressing falling of the material, it is good preferable to use a mat separator.

  The lead storage battery of the present invention is obtained by using a predetermined number of the above electrode plate groups. However, in the lead storage battery of the present invention, the reaction surfaces of the positive electrode plate and the negative electrode plate are substantially immersed in the electrolytic solution.

  When the lead storage battery of the present invention is an automotive lead storage battery having a normal nominal voltage of 12 V, six of the above-described electrode plate groups are housed in a battery case and the electrode plate groups are connected in series, The tank opening may be covered with a lid, and pole columns derived from the electrode plate groups located at both ends in series connection may be inserted into a terminal bushing that is insert-molded into the lid, and the terminal bushing and the tip of the pole column may be welded. Thereafter, dilute sulfuric acid electrolyte may be injected from a liquid inlet provided on the lid, and chemical conversion charging may be performed.

  In addition, after chemical conversion, the lead storage battery of the present invention has a configuration in which at least the electrode plate surfaces contributing to the charge / discharge reaction of the positive electrode plate and the negative electrode plate constituting the electrode plate group are all immersed in the electrolytic solution.

  In the embodiment described above, the battery according to the example of the present invention and the battery according to the comparative example shown in FIG. 1 were prepared by variously changing the configuration of the amount of Sb in the negative electrode active material, the negative electrode lattice, the separator and the like.

  The test battery type was a 55D23 type lead acid battery defined in JIS D5301 12V48Ah.

  In the life cycle number test, 1A CA discharge in a 40 degree environment and 14.5V constant voltage charge (maximum charge current 4.8A) 90 seconds are repeated every 500 cycles for 300A judgment discharge, and the voltage at the 5th second is It was determined by determining that the life was 8 V or less.

  The short-circuit occurrence rate indicates the rate at which a short-circuit occurred, assuming that the number of samples n = 10. 0% is when no short circuit occurred, and 100% is when all 10 are short-circuited. In addition, the short circuit in the present invention is not a short circuit due to deformation of the positive electrode plate that occurs due to overcharge, but is due to expansion / dropping of the negative electrode active material. When a short circuit occurred, a change in the color tone of the active material at the short circuit site occurred as the cell voltage decreased. In particular, although the positive electrode active material usually has a dark brown color, the area around the short-circuited portion was grayish white because it was converted to lead sulfate by a short-circuit.

  In the figure, the glass mat plate shape is a flat plate separator. The glass mat -U has a separator folded in half and a -plate arranged on the inside, and the glass mat + U has a separator folded in half and a + plate placed on the inside. The glass mat-bag is formed in a U-shape by folding the separator in half, and the overlapped side edges are joined together to form a bag with only the upper part opened, and a plate is placed in this bag. . Glass mat + bag is a bag in which a + plate is placed in the above bag. The polyethylene sheet-bag is the same as the glass mat-bag.

As a method for producing the bag, in the case of a polyethylene sheet, since it is a heat-welding material, mechanical sealing is performed while heating. In the case of a mat separator, when a polypropylene fiber is used, since this is also a heat-weldable material, the method is the same as that for a polyethylene sheet. In the case of glass fiber, a bag can be produced by the same method as that for a polyethylene sheet by bonding with a polypropylene resin-based hot melt agent or by mixing heat-weldable polypropylene fiber in glass fiber.

  In FIG. 1, A-1 to A-5 whose separator shape is plate-like are clearly inferior in both cycle life and short-circuit occurrence rate regardless of the amount of Sb. In addition, D1 to D5 and E-1 to E-5 whose separator shapes are -U-shaped are more effective in adding Sb than A-1 to A-5, but have a sufficient cycle life and a short-circuit occurrence rate. It is not.

  On the other hand, when B and C using a bag-shaped separator are seen, when the Sb amount is 1 to 30 ppm, both the cycle life and the short-circuit occurrence rate are good values. In particular, when the Sb content is 1 to 10 ppm, the cycle life exceeds 40,000 cycles, and a preferable value of 0% short-circuit occurrence rate is obtained.

  Further, when F and G using a cast lattice as a negative electrode lattice body were observed, the same tendency as that using an expanded lattice body was obtained. That is, using a bag-shaped separator, only G-2 having a Sb content in the range of 1 to 30 ppm showed a good value.

Furthermore bag-like polyethylene sheet as a separator - If using the bag, although Ru Riretsu by when the cycle life characteristics using a glass mat, the amount of Sb exhibits generally good value if the range of 1~30ppm Can be read.

Summarizing the above, the present invention comprises, as shown in the claims, a positive electrode / negative electrode plate composed of a positive electrode lattice and a negative electrode lattice not containing Sb, and a bag-like mat separator covering the negative electrode plate, It has an effect on a lead storage battery in which the entire surface of the positive electrode / negative electrode plate is immersed in an electrolytic solution, uses an expanded lattice as the negative electrode lattice , and contains 1 to 30 ppm of Sb in the negative electrode active material. in an effect that significantly improves the life characteristics of high productivity lead-acid battery.

  According to the lead acid battery of the present invention, it has an effect of remarkably improving the life characteristics by improving the charge acceptability of the negative electrode in the charge / discharge cycle of the lead acid battery, so that it is extremely useful industrially and highly reliable. This is suitable for an idle stop vehicle or a vehicle equipped with a regenerative brake system.

Characteristic diagram showing the present invention and a comparative example Diagram showing a typical expansion Diagram showing a typical casting grid

Claims (2)

A positive electrode / negative electrode plate composed of a positive electrode lattice and a negative electrode lattice not containing Sb, and a bag-like mat separator covering the negative electrode plate, and the entire electrode plate surface of the positive electrode / negative electrode plate is immersed in an electrolyte; A lead-acid battery for use in an idle stop vehicle or a vehicle equipped with a regenerative brake system , wherein an expanded lattice is used as the negative electrode lattice, and only the negative electrode contains 1 to 30 ppm of Sb in the active material.   The lead acid battery according to claim 1, wherein Sb contained in the negative electrode active material is 1 to 10 ppm.

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