JP4904675B2 - 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 vehicles that stop the engine while the vehicle is temporarily stopped, and regenerative braking systems that convert kinetic energy resulting from vehicle deceleration into electrical energy and store this electrical energy have been put into practical use. .

  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, so the depth of discharge inevitably increases. Further, 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% lower than that in the past 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 lead-acid batteries in such a deep discharge life are the deterioration of the active material in the positive electrode due to deep discharge, the increase in impedance due to the formation of a high resistance layer at the active material-lattice interface, and the decrease in charge acceptance of the negative electrode active material. Met.

  Moreover, if the charge acceptance property in a negative electrode active material falls, the charge potential of a negative electrode will shift to a base, and will raise a charge voltage. In order to suppress gas generation in the lead storage battery, so-called constant voltage charging control is performed in which the maximum charging voltage per cell is controlled to about 2.3 to 2.5V. Therefore, due to the transition of the negative electrode charging potential as described above, the charging voltage value rises to the charging control voltage value at an early stage of charging, and the charging current drops.

  Due to such drooping of the charging current, the amount of charge electricity to the lead storage battery cannot be secured, and the lead storage battery is in an insufficiently charged state. In particular, when the insufficient charging state is repeatedly performed in the positive electrode, the bonding between the positive electrode active materials is impaired, the capacity deterioration progresses at an early stage, and the lead-acid battery has a short life.

  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.

In particular, a part of antimony disposed on the surface of the positive electrode lattice is trapped by the positive electrode active material, but a small amount of the other part elutes in the electrolytic solution and is deposited on the negative electrode plate. Antimony deposited on the negative electrode active material has a function of lowering the charging voltage by preciously shifting the charging potential of the negative electrode. As described above, the reduction of the charging voltage in the constant voltage charging control increases the charging current. As a result, the amount of charged electricity in the positive electrode was secured, and the deterioration of the positive electrode due to insufficient charging and the short life of the storage battery due to this were suppressed.

Such a configuration as disclosed in Patent Document 1 is very effective in a conventional lead-acid battery for starting that is used in a charged state in which the 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 lead having only the configuration as in Patent Document 1 is used. In the storage battery, although the life of the positive electrode can be secured, there has been a problem that the rate of water decrease in the electrolytic solution increases rapidly at the end of the life.

  Such a rapid increase in the rate of water reduction in the electrolyte causes exposure of the electrode plate group, particularly the negative electrode shelf, from the electrolyte in a short period of time that a lead-acid battery user cannot expect. As a result, corrosion progressed at the negative electrode shelf and the negative electrode ear, which could lead to disconnection.

  Even when the negative electrode shelf and the negative electrode ear are immersed in the electrolyte, a small amount of antimony deposited on the negative electrode ear causes the negative electrode ear to corrode, reducing the negative electrode ear thickness and reducing the concentration at the negative electrode. There was a problem of reducing the electric efficiency.

  The present invention drastically improves the deep discharge life characteristics by improving the deterioration of the positive electrode in the deep discharge and the charge acceptability in the negative electrode as described above, and also reduces the rate of water decrease in the electrolyte at the end of the life. By suppressing the increase, it is excellent in maintenance-free properties, and by suppressing corrosion at the negative electrode ear, it is possible to provide a lead storage battery suitable for an idle stop vehicle or a vehicle equipped with a regenerative brake system having high reliability. Objective.

Lead-acid battery of the present invention in order to achieve the above object, the surface in contact with the negative electrode plate comprising a negative electrode grid and the anode active material containing no Sb, the positive electrode active material is composed of a positive grid and positive active material containing no Sb A positive electrode plate having a layer containing 0.01 to 0.15 wt% of Sb in the amount of the positive electrode active material, and a separator interposed between the positive electrode and the negative electrode plate. The entire surface of the electrode plate is immersed in an electrolyte solution, and Bi is contained in the negative electrode active material in an amount of 0.02 to 0.10 wt% with respect to the amount of the negative electrode active material.

  Thereby, the deterioration of the positive electrode in the deep discharge and the charge acceptability in the negative electrode can be improved, and the deep discharge life characteristics can be drastically improved. In addition, at the end of the service life, it is excellent in maintenance-free by suppressing the increase in the rate of water decrease in the electrolyte, and also highly reliable idle stop cars and regenerative brakes by suppressing corrosion at the negative electrode ear. A lead-acid battery suitable for a system-equipped vehicle or the like can be provided.

According to the lead storage battery of the present invention, the deterioration of the positive electrode in the deep discharge and the charge acceptability in the negative electrode can be improved, and the deep discharge life characteristics can be dramatically improved. In addition, at the end of the service life, it is excellent in maintenance-free by suppressing the increase in the rate of water decrease in the electrolyte, and also highly reliable idle stop cars and regenerative brakes by suppressing corrosion at the negative electrode ear. A lead-acid battery suitable for a system-equipped vehicle or the like can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described. The base material of the positive electrode lattice 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. Preferably it is 1.20-1.80 mass%. In the present invention, the fact that Sb is not substantially contained in the positive electrode lattice means 0.002 mass% or less. Even if this amount of Sb is contained in the positive electrode grid, it does not migrate to the negative electrode, and as a result, it affects the self-discharge amount in the negative electrode and the maintenance-free performance of the lead storage battery, such as the reduction of the electrolyte. There is no.

In the present invention, a layer containing Sb such as a Pb—Sb alloy is formed on at least a part of the surface of the positive electrode lattice not containing Sb in contact with the positive electrode active material, and the amount of Sb contained in this layer is determined based on the amount of Sb contained in this layer. The range is 0.01 to 0.15 wt% with respect to the amount of substance .

  As a method for 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, it is also preferable that Sn of about 2.0 to 7.0% by mass is contained in the layer containing Sb on the surface of the positive electrode lattice.

  The positive electrode grid is filled with a positive electrode active material paste and then aged and dried to obtain an unformed positive electrode plate. 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, similarly to the positive electrode lattice, the negative electrode lattice is made of a lead alloy substantially not containing Sb. 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. Moreover, the manufacturing method of a negative electrode grating | lattice can be obtained by the method similar to a positive electrode grating | lattice.

  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 the present invention, 0.02 to 0.10 wt% Bi is contained in the negative electrode active material after chemical conversion with respect to the amount of the negative electrode active material.

  As a method for adding Bi in the negative electrode active material, it can be added as a bismuth compound such as bismuth oxide or bismuth sulfate during kneading of the negative electrode active material paste. As another method, it is also an extremely effective method to deposit Bi on the negative electrode active material by adding the above-described bismuth compound to the dilute sulfuric acid electrolyte before the chemical charging step and performing chemical charging. It is.

The negative electrode plate and the positive electrode plate described above are combined with a mat separator or polyethylene separator made of acid-resistant fibers such as glass fibers and polypropylene resin fibers to constitute an electrode plate group. The lead storage battery of this invention can be obtained by comprising a lead storage battery using this electrode group.

  When the lead-acid battery of the present invention is a normal lead-acid battery for automobiles having a nominal voltage of 12 V, six of the electrode plate groups described above are housed in a battery case, and the electrode plate groups are connected in series, and then the battery case opening The part 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.

  The lead-acid battery according to the present invention having the above-described configuration can prevent Sb from being deposited on the negative electrode while trapping Sb in the positive electrode active material and suppressing it to the extent that it does not flow out into the electrolyte and deposit on the negative electrode. By compensating for the decrease in charge acceptability of the negative electrode due to the addition of Bi, a long life and high reliability can be obtained.

  Further, when the amount of Sn contained in the positive electrode lattice base material is 0.80 to 1.80 wt%, the positive electrode lattice corrosion is suppressed, so that the life is extremely long, and as a result, it is used for a long time. The problem of the present invention is a new problem that occurs as the usage period becomes longer, and it is most preferable to apply the configuration of the present invention to such a long-life lead-acid battery.

  FIG. 1 shows a positive electrode surface layer which is a layer containing Sb, an Sb amount (wt%) in the positive electrode surface layer with respect to the positive electrode active material mass, and an Bi amount (wt%) in the negative electrode active material with respect to the negative electrode active material mass. The cycle life characteristics, ear corrosion amount, and liquid reduction amount when a lead storage battery is created as parameters are shown.

  The test battery type was a 55D23 type lead acid battery defined in JIS D5301 “Starting Lead Acid Battery”.

  The cycle life characteristics were measured in the gas phase of 75 degrees by changing the 4-minute discharge of JIS D5301 “light load life” to the 5-minute discharge. That is, every time 480 cycles of 25A discharge for 5 minutes and 14.8V constant voltage (maximum current 25A) are repeated for 480 cycles, determination discharge for 356A for 30 seconds is performed, and when the end-of-discharge voltage becomes 7.2V or less, the life is determined. went.

  The amount of ear corrosion (%) was determined by repeating 25A discharge 60 seconds and 15V constant voltage charge 60 seconds for 150 cycles, followed by 14.5V constant voltage charge for 1 hour and storing for 6 weeks. The rate of decrease in cross-sectional area is compared.

  The amount of liquid reduction (%) is a comparison of the weight loss (%) of the electrolyte before and after the test after repeating 500 cycles of 48 A discharge 60 seconds and 14.5 V charge (maximum current 48 A) 90 seconds.

  The batteries A1 to A5 in the figure do not have a layer containing Sb in the positive electrode surface layer. In this case, the ear corrosion amount and the liquid reduction amount are the same level as the layer containing Sb in the positive electrode surface layer, but it is understood that the cycle life characteristics are considerably inferior.

  The batteries B1 to B5 in the figure contain Sb in the positive electrode surface layer in an amount of 0.005 wt% of the positive electrode active material amount. In this case, the ear corrosion amount and the liquid reduction amount are the same as those of the battery A. In addition, the cycle life characteristics are slightly improved compared to the battery A, but are not sufficiently effective.

Batteries C, D, E, and F in the same figure contain 0.01 wt%, 0.1 wt%, 0.15 wt%, and 0.2 wt% of Sb in the positive electrode surface layer, respectively. In this case, for batteries C2 to C4, D2 to D4, E2 to E4, and F2 to F4 containing 0.02 to 0.10 wt% of Bi in the negative electrode active material, the cycle is Good results have been obtained for all parameters of life characteristics, ear corrosion amount, and liquid reduction amount. In particular, the batteries C2 to C4, D2 to D4, and E2 to E4, in which the Sb amount is 0.01 to 0.15 wt% of the positive electrode active material amount and the Bi amount is 0.02 to 0.10 wt% of the negative electrode active material amount, It can be seen that the amount of ear corrosion and the amount of liquid reduction are superior to those of the battery F having an Sb content of 0.2 wt%. However, the cycle life characteristics are not sufficiently extended for C1, D1, E1, and F1 with a small amount of Bi in the negative electrode active material. On the other hand, although C5, D5, E5, and F5 with a large amount of Bi in the negative electrode active material have improved cycle life characteristics, they are not practical because the amount of liquid reduction increases.

  It can also be seen that when the Sb amount of the positive electrode surface layer is increased to 0.25 wt% of the positive electrode active material amount (battery G), extremely bad results are obtained in terms of ear corrosion amount and liquid reduction amount.

  Further, when the battery H containing moderate Sn in the positive electrode surface layer is seen, it can be seen that better results are obtained in terms of cycle life characteristics than in the case of not containing Sn (battery D). It can be seen that the present invention is more effective when the present invention is used.

  According to the present invention, it is possible to dramatically improve the deep discharge life characteristics by improving the deterioration of the positive electrode in the deep discharge and the charge acceptability in the negative electrode, and also the rate of water decrease in the electrolyte at the end of the life. It is possible to provide a lead-acid battery with a long service life and high reliability by suppressing corrosion at the negative electrode ear, and is equipped with an idle stop vehicle and a regenerative brake system. It is useful in a lead acid battery for automobiles that is frequently used in a low SOC region such as that used in cars.

Characteristic diagram showing the present invention and a comparative example

Claims (1)

A negative electrode plate composed of a negative electrode lattice not containing Sb and a negative electrode active material , a positive electrode active material amount of 0.01 to at least part of a surface composed of a positive electrode lattice not containing Sb and a positive electrode active material and in contact with the positive electrode active material A positive electrode plate having a layer containing 0.15 wt% Sb, and a separator interposed between the positive electrode and the negative electrode plate, and the entire surface of the electrode plate of the positive electrode / negative electrode plate is immersed in an electrolyte solution; A lead-acid battery characterized in that the negative electrode active material contains Bi in an amount of 0.02 to 0.10 wt% with respect to the amount of the negative electrode active material .

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