JP2006114235A - Lead acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead acid storage battery having superior life characteristics and high reliability by suppressing movement of Sb to a negative electrode in the lead acid storage battery which is stored for a long period as a stock such as more than six months from the manufacturing till actual use. <P>SOLUTION: The lead acid storage battery comprises a positive electrode plate 1 in which a positive electrode active material 3 is filled in positive electrode grid 2, a negative electrode plate in which a negative electrode active material is filled in a negative electrode grid, and a separator which is installed between the positive electrode plate and the negative electrode plate. The positive electrode grid is constructed of Pb-Ca-Sn alloy matrix and a surface layer 4 made of Pb-Sb-Ba alloy is provided at least at a part of a face where the positive electrode grid contacts the positive electrode active material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 start lead-acid battery supplies power to various electric and electronic devices mounted on the vehicle as well as power to the engine start cell motor. After the engine is started, the battery is charged by the alternator. Here, the output voltage and output current of the alternator are set so that charging and discharging of the battery are balanced and the SOC (charged state) of the battery is maintained at 90 to 100%. Such a lead acid battery for starting is different from a lead acid battery for cycle service, and is used at a relatively high SOC.

  On the other hand, one of the main deterioration modes of the lead acid battery for starting is deterioration of the positive electrode plate due to overcharge. This deterioration is mainly due to corrosion of the positive electrode grid body due to overcharge, and this corrosion reduces the current collection efficiency of the grid body, and the positive electrode extends due to the volume expansion of the grid body due to corrosion. Cause a short circuit.

  In order to suppress such corrosion in the positive grid, the positive grid alloy composition has been studied conventionally. In particular, in the field of so-called maintenance-free start-up lead storage batteries in which self-discharge and liquid reduction are suppressed, Sb is not included in the positive electrode lattice, Ca, Sn addition amount, Bi, Ba, etc. in the Pb-Ca-Sn alloy The alloy components are being studied. Among them, for example, as described in Patent Document 1, a lattice body obtained from a rolled body of a Pb—Ca—Sn alloy containing 0.03 to 0.08 wt% Ca and 0.5 to 1.8 wt% Sn. Is excellent in corrosion resistance and can be used for a positive electrode grid of a lead storage battery to obtain a long-life lead storage battery.

  Thus, although the positive electrode lattice obtained from the rolled material of the Pb—Ca—Sn alloy has the advantage of being excellent in corrosion resistance, on the other hand, since the lattice does not contain Sb, the positive electrode was an advantage of Sb. The effect of improving the bonding force between the active materials and between the positive electrode lattice and the active material cannot be obtained. In addition, the rolled material has a very smooth surface as compared with the conventional cast lattice, and the physical bonding force between the positive electrode lattice and the active material is reduced as described above.

  In such a situation, when the charge / discharge cycle of the lead-acid battery is repeated, there is a problem that the positive electrode active material is further refined and detached from the electrode plate, the capacity is reduced, and the life is reached. In order to improve the life characteristics of the lead-acid battery resulting from such a positive electrode, for example, Patent Document 2 shows that a layer containing Sb is formed at the interface in contact with the active material of the positive electrode grid. Part of the Sb present at the positive electrode lattice-active material interface is transferred to the positive electrode active material, improving the bonding strength between the positive electrode active materials as described above and between the positive electrode lattice and the active material, as described above. It is known to suppress a decrease in life caused by the positive electrode.

As described above, the configuration in which Sb is arranged on the surface of the Pb—Ca—Sn positive electrode lattice utilizes the characteristics of the Pb—Ca—Sn lattice excellent in corrosion resistance optimum for the positive electrode lattice, and the conventional Pb—Sb alloy lattice. It is useful because it can achieve both the positive electrode reforming effect brought about by Sb and improve the life characteristics of the lead-acid battery at a relatively low cost.
Japanese Patent Laid-Open No. 5-343070 JP-A 63-148556

  However, although Sb arranged on the surface of the positive electrode lattice gradually elutes into the positive electrode active material to improve the characteristics of the positive electrode active material, a part of the eluted Sb is eluted into the electrolyte and moves to the negative electrode. Over time, Sb on the surface of the positive electrode lattice moves to the negative electrode via the positive electrode active material in order to reduce the self-discharge characteristics or increase the amount of water decrease in the electrolyte (hereinafter referred to as “liquid reduction amount”). As a result, there is a problem that the effect of the positive electrode reforming by Sb is lowered.

  Such a problem has been serious when, for example, a lead storage battery is used after being left in stock for a long time after manufacturing. That is, when Sb is eluted from the positive electrode lattice surface into the stock for a long time and diffuses into the electrolyte, the effect of arranging Sb on the positive electrode lattice surface, that is, the life extension effect cannot be obtained sufficiently. was there. Nowadays, lead-acid batteries for starting have various distribution forms in the market, and in some cases, the period of actual use from the production of lead-acid batteries may be longer than half a year. If the distribution period is long, the intended life performance cannot be obtained.

  An object of the present invention is to provide a highly reliable lead storage battery having excellent life characteristics even in such a lead storage battery stocked for a long period of time.

  In order to achieve the above object, the present invention provides a lead-acid battery in which a surface layer of a Pb-Sb-Ba alloy is formed on a part of the surface in contact with the positive electrode active material of a positive electrode lattice made of a Pb-Ca-Sn alloy base material. It is formed.

  Further, the amount of Ba contained in the surface layer is preferably 0.3 to 7.0 wt%, and the amount of Ba contained in the surface layer is more preferably 3.5 to 7.0 wt%. .

  With such a configuration of the present invention, it is possible to suppress the deterioration of the life characteristics even when the lead storage battery is left for a long period. In particular, by adding Ba to the Sb-containing layer, Sb elution from the Sb layer included during the standing period is suppressed, and Sb is retained in the positive electrode even after being left for a long period of time. Can be obtained. Moreover, since this suppresses the transition of Sb to the negative electrode, it is possible to improve the liquid reduction performance after standing for a long time.

  Embodiments of the present invention will be described below.

  The positive grid 2 used in the lead storage battery of the present invention is based on a Pb—Ca—Sn alloy. The base material may be a rolled material of a Pb—Ca—Sn alloy. The amount of Ca in the positive electrode lattice is suitably 0.03 to 0.10 wt% from the viewpoint of lattice strength, and the amount of Sn is suitably 1.00 to 2.00 wt% from the viewpoint of lattice strength and corrosion resistance. is there.

  In the present invention, the surface layer 4 of Pb—Sb—Ba alloy is formed on at least a part of the surface of the positive electrode grid 2 used for the positive electrode plate 1 in contact with the positive electrode active material 3. Here, Sb contained in the surface layer 4 is added for the purpose of ensuring the bonding force between the positive electrode active materials and between the positive electrode lattices and the active material by being present at the positive electrode lattice-active material interface. In order to obtain these effects, the amount of Sb is suitably in the range of 1.0 to 7.0 wt%.

Further, the amount of Ba contained in the surface layer 4 is in the range of 0.3 to 7.0 wt%, preferably 3.5 to 7.0 wt%. Ba contained in the surface layer 4 has an action of improving the corrosion resistance of the surface layer 4. By improving the corrosion resistance of the surface layer 4, the elution rate of Sb to the positive electrode active material is reduced, and Sb is prevented from dissipating to the positive electrode active material, the electrolytic solution, and the negative electrode at an early stage due to the elution. As a result, Sb remains on the surface of the positive electrode lattice for a relatively long period of time and gradually moves to the positive electrode active material, so that the positive electrode reforming effect by Sb and the life extension effect by this can be obtained more continuously. .

  In addition, as a manufacturing method of the positive electrode grid 2, it can obtain with good productivity by using a rolled sheet obtained by superimposing a Pb—Sb—Ba alloy sheet on a base alloy slab and rolling and integrating the two. . A positive electrode plate used in the lead storage battery of the present invention can be obtained by subjecting this rolled sheet to a punching process such as a punching process or an expanding process, filling it with an active material paste, and cutting it into a single electrode plate.

  In addition, in order to obtain a high output lead-acid battery, when an ultra-thin type, for example, a positive electrode grid having a thickness of about 0.1 to 0.5 mm is adopted, the rolled sheet is not subjected to drilling, and is directly applied on the rolled sheet. A material paste or an active material slurry may be applied.

  And the lead acid battery of this invention is assembled as a lead acid battery by the usual method using this positive electrode plate. In particular, in the present invention, since the Pb—Ca—Sn alloy is used for the base material of the positive electrode lattice 2 in consideration of maintenance-free property, the Pb—Ca alloy, Pb containing no Sb in the lattice also in the negative electrode. Needless to say, it is preferable to use Pb alloy such as -Ca-Sn alloy or Pb.

  A conventionally known positive electrode active material paste can be used. Needless to say, for example, a red lead for the purpose of improving chemical conversion efficiency, a tin compound such as tin sulfate or tin oxide, or a carbon added for the purpose of improving the initial capacity characteristics can be used.

  Various batteries shown in Table 1 were produced. The battery is a 55D23 type lead storage battery for start-up specified by JIS D5301 (1999).

次いで表１に示される電池について、寿命試験、放置後の寿命試験、減液性能試験を行い、その結果を表２に示す。

Subsequently, the battery shown in Table 1 was subjected to a life test, a life test after being left to stand, and a liquid reduction performance test. The results are shown in Table 2.

ここで、寿命試験は、７５℃気相中で、２５Ａ、４分間放電を行った後１４．８Ｖ（最大電流２５Ａ）、１０分間充電を行ったものを一サイクルとし、前記サイクルの４８０サイクル毎に２５℃気相中で、３５６Ａ、３０秒放電時の放電末期電圧を測定し、前記放電末期電圧が７．２Ｖに低下するまでのサイクル数を寿命サイクル数とした。

Here, the life test is performed in a gas phase of 75 ° C. for 25 A for 4 minutes and then 14.8 V (maximum current 25 A) and charged for 10 minutes as one cycle, and every 480 cycles of the above cycle. In the gas phase at 25 ° C., the end-of-discharge voltage at the time of 356 A, 30-second discharge was measured, and the number of cycles until the end-of-discharge voltage decreased to 7.2 V was defined as the number of life cycles.

  Further, in the liquid reduction performance test (measurement of the liquid reduction amount), after charging in a 40 ° C. water tank for 14.4 V (constant voltage) for 500 hours, the decrease in mass before and after charging was defined as the liquid reduction amount.

  In addition, the life cycle test and the liquid reduction performance test of the left battery in Table 2 were conducted in an open circuit state at 40 ° C. for 4 months, and then charged at 15.0 V constant voltage, maximum current 25 A, 25 ° C. environment. A life test and a liquid reduction performance test were performed under the above conditions for the battery that was supplemented for 6 hours under the above conditions.

  As is clear from the results of Table 2, in the battery A having no surface layer, a decrease in the number of life cycles is recognized. Further, even in the case of a battery having a surface layer, since the amount of liquid reduction is greatly increased in the battery B in which Ba is not included in the positive electrode lattice base material, the liquid level is regularly controlled every predetermined period. Even during this period, the liquid level falls below the minimum liquid level during this period, the negative electrode strap and the electrode plate are exposed from the electrolyte, and the capacity decrease proceeds rapidly, and corrosion occurs in the negative electrode strap. .

  On the other hand, in the battery (battery C to battery I) using the Pb—Sb—Ba alloy as the surface layer, both the life cycle characteristics and the liquid reducing performance are good, and in particular, the Ba amount is 0.3 to 7 A preferable result was obtained that the liquid reduction performance was further improved at 0.0 wt%, and that the life characteristics were further improved with a battery of 3.5 to 7.0 wt%.

  Since the lead storage battery according to the present invention has excellent life characteristics, it is useful as a lead storage battery that is stored as a long-term inventory.

Cross-sectional view of the positive electrode plate of the lead storage battery of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Positive electrode grid 3 Positive electrode active material 4 Surface layer

Claims (3)

A lead-acid battery comprising: a positive electrode plate in which a positive electrode grid is filled with a positive electrode active material; a negative electrode plate in which a negative electrode grid is filled with a negative electrode active material; and a separator provided between the positive electrode plate and the negative electrode plate. And
The positive electrode grid is composed of a Pb—Ca—Sn alloy base material,
A lead-acid battery in which a surface layer made of a Pb-Sb-Ba alloy is provided on at least a part of a surface of the positive electrode grid body in contact with the positive electrode active material. The lead acid battery according to claim 1, wherein an amount of Ba in the surface layer is 0.3 to 7.0 wt%. The lead acid battery according to claim 1, wherein an amount of Ba in the surface layer is 3.5 to 7.0 wt%.

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