JPWO2012153464A1 - Negative electrode for lead acid battery and lead acid battery - Google Patents

Abstract

The negative electrode for a lead storage battery according to the present invention includes a lattice made of a lead alloy containing no antimony and an active material paste filled in the lattice, and is electrically connected to another negative electrode at one end of the lattice. A tab portion of the lattice is provided, and an alloy layer containing antimony is provided on a part of the surface of the lattice. On the side of the end opposite to the one end of the lattice, the alloy layer is Covered with material paste and not exposed.

Description

  The present invention relates to a lead-acid battery having an alloy layer containing antimony on a part of the surface of a lattice of a negative electrode.

  2. Description of the Related Art In recent years, an idling stop technology that automatically stops an engine while the vehicle is stopped has been attracting attention for the purpose of improving automobile fuel efficiency. Since the lead acid battery mounted on the idling stop vehicle is charged only during traveling, the DOD (depth of discharge) tends to increase. There are two major concerns in using lead-acid batteries in areas where the DOD is large.

The first concern is that the positive electrode active material is promoted to fall off from the positive electrode. In charge / discharge, the lead-acid battery exchanges electrons by causing the positive electrode active material PbO ₂ and the negative electrode active material Pb to undergo an oxidation-reduction reaction with the electrolytic solution H ₂ SO ₄ . For example, when discharged, the active material becomes PbSO ₄ for both the positive electrode and the negative electrode, and these are returned to PbO ₂ (positive electrode) and Pb (negative electrode) when charged. For this reason, the crystal structure of the positive and negative electrode active materials changes every time charging and discharging are repeated. In particular, when the positive electrode active material is repeatedly charged and discharged, the bonding force between the active materials decreases and softens (softens). As the softening of the positive electrode active material proceeds, the positive electrode active material gradually falls off from the positive electrode, so that the battery capacity decreases. This phenomenon tends to progress as the DOD increases. However, since this phenomenon gradually increases the internal resistance, the user can infer the end of life due to this phenomenon from the transition of the internal resistance.

The second concern is sudden death due to breakage of the negative electrode ear (tab-like portion for collecting current). Sudden death is a phenomenon that suddenly becomes impossible to charge and discharge without any foresight. In the portion of the negative electrode that is far from the ear (current collection mechanism), a phenomenon (sulfation) that is inactivated due to the formation of large PbSO ₄ crystals is likely to proceed. This part is particularly inactive in a state where the DOD is large, and when charging is started in this state, the negative electrode ear part with small polarization becomes thin and thin. By repeating this, the negative electrode ear part breaks suddenly and loses its function as a battery. Since this phenomenon suddenly becomes impossible to discharge, it is impossible for the user to infer the end of life from the transition of the internal resistance.

  Therefore, in order to eliminate the second concern that sudden death occurs as described above, and to make it easier for the user to estimate the end of life, a technique such as Patent Document 1 has been proposed.

JP 2009-266514 A

  Although a lead storage battery suitable to some extent for an idling stop vehicle can be manufactured according to Patent Document 1, power generation by an alternator is concentrated at the time of deceleration of an automobile, and the lead storage battery is exposed to a region where the DOD is larger, while the demand for improving fuel efficiency increases. It has been found that sudden death occurs again. This sudden death did not occur by the mechanism described as the second concern above, but was a sudden death by a mechanism that had not been known so far.

  An object of the present invention is to solve this problem, and to provide a negative electrode for a lead storage battery and a lead storage battery suitable for an idling stop vehicle that does not suddenly die even when exposed to a region where the DOD is significantly large. .

  In order to solve the above-mentioned problems, a negative electrode for a lead storage battery according to the present application is a negative electrode for a lead storage battery comprising a lattice made of a lead alloy containing no antimony and an active material paste filled in the lattice, A tab for electrically connecting to another negative electrode is provided at one end of the lattice, and an alloy layer containing antimony is provided on a part of the surface of the lattice, On the end side opposite to the one end, the alloy layer is covered with the active material paste and is not exposed.

  The antimony concentration in the alloy layer is preferably 0.1% by mass or more and 10% by mass or less, and the antimony concentration in the alloy layer is more preferably 1% by mass or more and 5% by mass or less.

  The thickness of the alloy layer is preferably 0.1 μm or more and 500 μm or less, and the thickness of the alloy layer is more preferably 0.1 μm or more and 100 μm or less.

  The lead storage battery of the present application comprises a positive electrode formed by filling a lead alloy grid with an active material paste and the above-mentioned negative electrode for a lead storage battery through a separator to constitute an electrode plate group. It has the structure accommodated in the tank.

  An alloy layer containing antimony may be provided on the surface of the positive electrode lattice.

  When the lead storage battery of the present invention is used, even when the discharge that reaches the region where the DOD is remarkably large is repeated as in the idling stop vehicle in which the charging opportunity is controlled, it is caused by the winding and adhesion of the dropped positive electrode active material. Prevents internal short circuit and extends life.

Schematic which shows an example of the grating | lattice used for the negative electrode for lead acid batteries of embodiment. Schematic which shows the negative electrode for lead acid batteries of embodiment. Schematic cross-sectional view showing problems in the configuration of the comparative form Schematic cross-sectional view showing the effect of the configuration of the embodiment Schematic showing the lead-acid battery of the embodiment The figure showing the experimental result which shows the effect of embodiment The figure showing the experimental result which the desirable mode of an embodiment shows The figure showing the experimental result which the desirable mode of an embodiment shows

  Before describing the embodiment of the present application, the background to the present invention will be described.

When a lead storage battery is used in a region where the DOD is relatively large (for example, 3% or more), the active material softened from the positive electrode at an early stage falls off. The fallout of the positive electrode active material is deposited on the bottom of the battery case. On the other hand, when an alloy layer containing antimony is provided on the surface of the grid (made of lead alloy) of the negative electrode as disclosed in Patent Document 1, the fallout of the positive electrode active material flies in the electrolyte solution. It was found that the part was deposited on top of the electrode plate group. The fallen matter deposited on the upper part of the electrode plate group is reduced to PbO ₂ (positive electrode) and Pb (negative electrode) by charging. If it does so, a positive electrode and a negative electrode will be connected and an internal short circuit will generate | occur | produce. For the first time, the inventors have found that sudden death occurs due to this internal short circuit.

  As a result of various studies, the inventors have generated local gas at the interface between the alloy layer containing antimony and the lattice, and gas is generated with convection. It was found that it tends to deposit on the top. Based on this knowledge, the alloy layer containing antimony that is indispensable for extending the life of the negative electrode prevents the interface between the alloy layer and the negative electrode lattice itself from being exposed to the electrolyte solution as in Patent Document 1. It was decided. Specifically, the boundary portion between the alloy layer and the negative electrode lattice itself is covered with the negative electrode active material at the lower portion of the negative electrode lattice so as not to be exposed, or the alloy layer is not provided at the lowermost portion. As a result, the interface between the alloy layer and the lattice is not exposed at the bottom of the negative electrode closest to the cathode active material fallout, so that no gas is generated, and the cathode active material fallout reaches the top of the electrode plate group. The opportunity to roll up has drastically decreased. As a result, the above-mentioned unexpected sudden death can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a lattice used for the negative electrode for lead storage battery of the embodiment, and FIG. 2 is a schematic view showing the negative electrode for lead storage battery of the embodiment. The lattice shown in FIG. 1 is a reciprocating expanded lattice (made of a lead alloy), and can contain calcium, tin, and the like in addition to lead. The lead alloy constituting the lattice does not contain antimony. Here, the antimony is not contained in the lattice skeleton, and an alloy layer containing antimony is formed on a part of the surface of the lattice as will be described later.

  A substantially rhombic mesh portion 3 is connected under the upper frame portion 1 having the ear portions (tab portions) 2. In the case of a rotary type expanding lattice, the lower frame portion is connected to the mesh portion 3 further below. By filling the lattice (particularly, the mesh portion 3) with the active material paste 5, a negative electrode for a lead storage battery is formed. The plurality of negative electrodes are electrically connected to each other at the ear 2 portion.

  The negative electrode for a lead storage battery of this embodiment is provided with an alloy layer 4 containing antimony on the surface of the lattice 20 excluding the lowermost part, and the alloy layer 4 is not exposed at the lowermost part.

  FIG. 3 is a diagram showing a schematic configuration inside the lead storage battery according to the comparative embodiment. For ease of viewing, the electrolytic solution is omitted and not shown. In the comparative embodiment, the negative electrode 9b located on the left side of FIG. 3 is provided with the alloy layer 4 containing antimony at the bottom of the negative electrode lattice 20, and the negative electrode lattice 20 not containing antimony and the alloy layer containing antimony at the bottom. 4 is exposed, and the boundary between the two is also exposed in the electrolyte. The positive electrode 9a is located on the right side of FIG. The positive electrode 9 a is formed by filling the positive electrode active material 6 in the positive electrode lattice 30. A separator 9c is placed between the positive electrode 9a and the negative electrode 9b.

When a lead storage battery is used in a region where the DOD is remarkably large (for example, 3% or more), the positive electrode active material 6 softened from the positive electrode 9a falls off and accumulates relatively early. On the other hand, as shown in the comparative form, when the alloy layer 4 containing antimony is provided on the surface up to the lowermost part of the negative electrode lattice 20, as shown in FIG. There is an interface between the alloy layer 4 and the negative electrode lattice 20 in the lowermost portion of the near negative electrode 9b (A in the figure). This interface portion becomes a local battery. The gas generated by the local battery causes convection indicated by a solid arrow. Due to this convection, the fallen product 6a of the positive electrode active material 6 is carried to the upper portions of the positive electrode 9a and the negative electrode 9b and is deposited on the positive electrode 9a and the negative electrode 9b. When the fallout 6a is deposited on the positive electrode 9a and the negative electrode 9b, the distance between the positive electrode 9a and the negative electrode 9b is locally reduced. The fallen matter 6a of the positive electrode active material 6 deposited on the positive electrode 9a and the negative electrode 9b is reduced to PbO ₂ (positive electrode) and Pb (negative electrode) by charging. If it does so, an internal short circuit will occur in the part where distance between poles became small locally.

  In the present embodiment, the alloy layer 4 is not provided up to the lowermost part of the negative electrode lattice 20 as in the comparative embodiment, but is provided excluding the lowermost part as shown in FIG. The interface between the alloy layer 4 and the negative electrode lattice 20 is covered with the negative electrode active material 5 so as not to be exposed at the lowermost part of the near negative electrode (B in the figure). As a result, no gas is generated at the lowermost part of the negative electrode 9b, and the chance that the fallout 6a of the positive electrode active material 6 is carried to the upper part of the positive electrode 9a and the negative electrode 9b by convection is drastically reduced, and sudden death due to an internal short circuit can be suppressed. Become.

  Here, when the antimony concentration in the alloy layer 4 is 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, the effect of the present embodiment becomes remarkable. In order to improve the charge acceptability and to prolong the life of the negative electrode, the antimony concentration of the alloy layer 4 may be 0.1% by mass or more. However, when the antimony concentration of the alloy layer 4 is 10% by mass or more. When the charging current is remarkably increased, the amount of gas generated is increased, and the fallout 6a of the positive electrode active material deposited on the bottom is easily rolled up, and the effect of this embodiment is diminished.

  Moreover, the effect of this embodiment becomes further remarkable when the thickness of the alloy layer 4 is 0.1 μm or more and 500 μm or less, more preferably 0.1 μm or more and 100 μm or less. In order to improve the charge acceptability and prolong the life of the negative electrode, the thickness of the alloy layer 4 should be 0.1 μm or more. However, when the thickness of the alloy layer 4 is 500 μm or more, the charging current increases remarkably. By doing so, the amount of gas generation increases, and it becomes easy to wind up the fallen product 6a of the positive electrode active material deposited on the bottom, and the effect of this embodiment is reduced.

  The alloy layer 4 may contain tin, silver, etc. in addition to antimony and lead.

  The feature of the present embodiment is that “the alloy layer 4 containing antimony is not exposed by being covered with the negative electrode active material paste 5 at the bottom of the negative electrode lattice 20” as shown in FIG. Only the alloy layer 4 is not provided, and the active material paste 5 is provided up to the lower frame portion). Specifically, an aspect in which the alloy layer 4 is provided on the upper part of the lower frame part or an aspect in which the alloy layer 4 is not provided on the lower part of the mesh part 3 may be used. That is, the alloy layer 4 is not exposed at the lowermost part of the lattice 20 so that the convection shown in FIG. 3 does not occur. As a result, the adjacent lattice 20 and the alloy layer 4 are not exposed together. This is the main point of this embodiment.

  FIG. 5 is a schematic view showing an example of the lead storage battery of the present embodiment. The battery case 7 is an integral resin molded product composed of a partition wall 7a for dividing the interior into a plurality of cell chambers 8, a short side surface 7b, a long side surface 7c, and a bottom surface (not shown). In each of the cell chambers 8, an electrode plate group 9 in which the positive electrode 9 a and the negative electrode 9 b of the present embodiment are opposed to each other through a separator 9 c are accommodated and an electrolytic solution (not shown). And the ear | edge part (2 in the case of a negative electrode) of the polar board (the positive electrode 9a and the negative electrode 9b) of the same polarity in each electrode group 9 is connected to one connection component 10, and also through the through-hole provided in the partition 7a. Then, the connecting parts 10 of different polarities in the adjacent electrode plate group 9 are brought into contact with each other, and the contacted parts are resistance-welded under a predetermined condition. On the other hand, the ear portion of the positive electrode 9a of the cell chamber 8 at one end is connected to a positive pole column (not shown), and the ear portion 2 of the negative electrode 9b of the cell chamber 8 at the other end is connected to a negative pole column (not shown). Connect to The lead storage battery of this embodiment is formed by connecting each pole column to a bushing (not shown) integrated with the lid 11 to form the terminal 12 while sealing the opening of the battery case 7 with the lid 11. Is configured.

  Here, if a positive electrode in which an alloy layer containing antimony is provided on the surface of the lattice 30 for the purpose of improving the conductivity of the interface between the lattice and the positive electrode active material 6 in the positive electrode 9a, the lead storage battery of the present embodiment can be obtained. Higher performance is also achieved.

  Hereinafter, the effect of this embodiment will be described by way of examples.

  A positive electrode active material paste is prepared by kneading lead oxide powder with sulfuric acid and purified water, and a rolled sheet (composition is lead-calcium alloy) provided with an alloy layer of lead-tin-antimony on the surface is expanded by a reciprocating method. The positive electrode lattice 30 obtained by spreading was filled with this active material paste to produce a positive electrode 9a.

  On the other hand, a negative electrode active material paste is prepared by kneading an organic additive, barium sulfate, carbon, or the like added to lead oxide powder with sulfuric acid and purified water, and an alloy composed of lead-tin-antimony The active material paste is filled into a negative electrode lattice 20 obtained by expanding a rolled sheet (composition is lead-tin-calcium alloy) provided on the surface of the layer 4 under various conditions (details will be described later) by a reciprocating method, A negative electrode 9b (length 115 mm) was produced. The rolled sheet does not contain antimony.

  After the positive electrode 9a and the negative electrode 9b described above are aged and dried, the positive electrode 9a is wrapped with a bag-like separator 9c made of polyethylene, alternately overlapped with the negative electrode 9b, and the respective ears are welded to the connection component 10 to thereby form the electrode plate Group 9 was made. Then, the electrode plate group 9 is inserted into each cell chamber 8 of the battery case 7 composed of the six cell chambers 8, and the connecting parts 10 are welded through the holes provided in the partition wall 7a. Connected.

Furthermore, the lid 11 was welded and attached to the battery case 7, and the terminal 12 was constructed by welding the bushing and the pole column. Finally, an electrolytic solution made of dilute sulfuric acid is placed in all of the cell chambers 8 and the specific gravity of the electrolytic solution is adjusted to 1.280 g / cm ³ (converted to 20 ° C.) by carrying out battery cell formation. A lead storage battery was prepared.

  The examination was divided into three stages. First, in order to examine the applicable range of the present embodiment, the antimony concentration of the alloy layer 4 was set to 2 mass%, the thickness was fixed to 10 μm, and the surface of the lattice 20 where the alloy layer 4 was provided was examined. The conditions are shown in (Table 1). Here, “upper part”, “lower part”, and “intermediate part” of the lattice indicate respective parts obtained by dividing the lattice into five equal parts in the vertical direction, as shown in FIG. That is, the “upper part” is the uppermost 1/5, the “lower part” is an area obtained by subtracting the “lowermost part” to be described later from the lowermost 1/5, and the “middle part” indicates the middle 3/5. The “lowermost part” refers to a region from the lowest end of the lattice to 5 mm above.

  Second, in order to examine the optimum range of the present embodiment, the location where the alloy layer 4 is provided on the surface of the lattice 20 is “any location except the lowermost portion”, the thickness of the alloy layer 4 is 10 μm constant, and the alloy layer 4 The antimony concentration was changed. The conditions are shown in (Table 2).

  Third, in order to examine the optimum range of the present embodiment, the location where the alloy layer 4 is provided on the surface of the lattice is “any location except the bottom”, and the antimony concentration of the alloy layer 4 is constant 2% by mass. The thickness of layer 4 was varied. The conditions are shown in (Table 3).

  Each battery shown in (Table 1) to (Table 3) was subjected to a life test with an idling stop specification in which the opportunity for charging was controlled. Specifically, a modified pattern based on the battery industry association standard (SBA S 0101) was used as described below. Specifically, the tank temperature is 25 ° C. ± 2 ° C. (the wind speed in the vicinity of the lead storage battery is 2.0 m / second or less), and after performing the following “A → B” once, “C → D” is changed to 4 The pattern to be repeated was one cycle, and E was performed once every 50 cycles. Here, α is a measured value (%) of DOD calculated from the total amount of discharge (total amount of discharge electricity) in A and C in one cycle and the rated capacity of the lead storage battery.

A. Discharge at 48 A (24 × α) seconds Discharge, 1 second at 300 A C.I. Discharge at 48 A (3 × α) seconds Charging (14.5V constant voltage) at a limiting current of 72A (6 × α) seconds E. Charging (14.5 V constant voltage), until the current was attenuated to 5 A with a limiting current 72 A, a stand for 40 to 48 hours was provided every 3600 cycles. The number of cycles when the discharge voltage at B was less than 7.2 V was taken as a measure of life. Sample No. The life of various DODs studied using the batteries 1 to 5 is shown in FIG. 7 and 8 show the lifetimes at DOD = 3% using the batteries of 6 to 14 and 15 to 23, respectively.

  As can be seen from FIG. 6, No. 1 is provided with an alloy layer 4 containing antimony on the surface excluding the bottom of the lattice. The lead acid batteries 1 to 4 are No. 1 in which the alloy layer 4 is provided on the bottom surface of the lattice. Compared with 5-6 lead acid batteries, it can be seen that even when the charging opportunity is controlled and the DOD increases to 3%, excellent life characteristics are exhibited. As a result of comparing the composition of the alloy layer 4 with DOD = 3% constant, the antimony concentration was 0.1% by mass or more and 10% by mass or less (more preferably 1% by mass or more and 5% by mass or less). It can be seen that when the thickness is 1 μm or more and 500 μm or less (more preferably 0.1 μm or more and 100 μm or less), the effect of the present invention becomes more remarkable and the life is further extended.

  In the present embodiment, an example is shown in which the “lowermost part” is a region extending 5 mm above the lowest end of the lattice (the lowest 1/23 in the total length of 115 mm). Needless to say, if the interface does not exist, it can be defined as the “lowermost part” in this embodiment. For example, sample no. Since 1 and 2 show sufficient characteristics, it can be seen that when the lattice is divided into 5 equal parts in the vertical direction, the lowermost region of the lattice is 1/5, which is preferable.

(Other embodiments)
The above-described embodiment is an exemplification of the present invention, and the present invention is not limited to these examples, and these examples may be combined or partially replaced with known techniques, common techniques, and known techniques. Also, modified inventions easily conceived by those skilled in the art are included in the present invention.

  The mesh shape of the negative electrode lattice is not limited to a rhombus, and may be a rectangle or a circle. The negative electrode lattice, the positive electrode lattice, the negative electrode active material, and the material and composition of the positive electrode active material may be any known material or composition. The sizes of the negative electrode and the positive electrode are not limited to those of the examples.

  The lead storage battery of the present invention is capable of obtaining good life characteristics by suppressing internal short-circuits in an environment where frequent deep discharges such as idling stop are performed while controlling charging opportunities. Very useful.

1 Upper frame part 2 Ear part (tab part)
DESCRIPTION OF SYMBOLS 3 Net | network part 4 Alloy layer 5 Negative electrode active material paste 6 Positive electrode active material 6a Falling thing of positive electrode active material 7 Battery case 7a Partition 7b Short side surface 7c Long side surface 8 Cell chamber 9 Electrode plate group 9a Positive electrode 9b Negative electrode 9c Separator 10 Connection component 11 Lid 12 Terminal 20 Negative grid 30 Positive grid

Claims (7)

A negative electrode for a lead storage battery comprising a lattice made of a lead alloy containing no antimony and an active material paste filled in the lattice,
One end of the grid is provided with a tab portion for electrical connection with another negative electrode,
An alloy layer containing antimony is provided on a part of the surface of the lattice,
The negative electrode for a lead-acid battery, wherein the alloy layer is covered with the active material paste and is not exposed on the end opposite to the one end of the lattice.   2. The negative electrode for a lead storage battery according to claim 1, wherein the antimony concentration in the alloy layer is 0.1 mass% or more and 10 mass% or less.   The negative electrode for a lead-acid battery according to claim 2, wherein the antimony concentration in the alloy layer is 1% by mass or more and 5% by mass or less.   The lead-acid battery negative electrode according to claim 1, wherein the alloy layer has a thickness of 0.1 μm to 500 μm.   The negative electrode for a lead storage battery according to claim 4, wherein the alloy layer has a thickness of 0.1 µm or more and 100 µm or less.   A positive electrode formed by filling a lattice made of a lead alloy with an active material paste and the negative electrode for a lead storage battery according to any one of claims 1 to 5 through a separator to constitute an electrode plate group, Lead-acid battery stored in a battery case with liquid. The lead acid battery according to claim 6, wherein an alloy layer containing antimony is provided on a surface of the grid of the positive electrode.

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