Bipolar lead-acid battery

Abstract

To provide a bipolar lead-acid battery that, when using a positive electrode active material layer containing PbO2, ensures adhesion between a positive electrode active material layer and a positive electrode current collector, thereby improving the battery life while maintaining the capacity required for a battery.SOLUTION: A bipolar lead-acid battery includes a positive electrode active material layer 102, a negative electrode active material layer 103, a current collector 101 made of lead or a lead alloy in contact with either the positive electrode active material layer 102 or the negative electrode active material layer 103, or both, and a separator 104 disposed between the positive electrode active material layer 102 and the negative electrode active material layer 103 which face each other, the positive electrode active material layer 102 has a first surface layer 102a on the current collector 101 side and a second surface layer 102b on the separator 104 side, and the content of α-PbO2 contained in the first surface layer 102a is greater than the content of α-PbO2 contained in the second surface layer 102b.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to bipolar lead-acid batteries.

Background Art

[0002] In recent years, power generation facilities using natural energy such as sunlight and wind power have been increasing. In such power generation facilities, since the power generation amount cannot be controlled, a storage battery is used to level the power load. That is, when the power generation amount is larger than the consumption amount, the difference is charged to the storage battery, while when the power generation amount is smaller than the consumption amount, the difference is discharged from the storage battery. As the above-described storage battery, lead-acid batteries are frequently used from the viewpoints of economy and safety. As such a conventional lead-acid battery, for example, the one described in Patent Document 1 below is known.

[0003] In the lead-acid battery described in this Patent Document 1, a substrate made of resin is attached inside a frame (rim) made of resin having a frame shape. On one surface and the other surface of the substrate, a current collector for the positive electrode and a current collector for the negative electrode are provided. An active material layer for the positive electrode is adjacent to the current collector for the positive electrode. An active material layer for the negative electrode is adjacent to the current collector for the negative electrode. And these together constitute a bipolar electrode plate. Further, inside a spacer made of resin having a frame shape, a glass mat (electrolyte layer) containing an electrolyte is disposed. Then, a plurality of the frames and spacers are alternately stacked and assembled.

[0004] Furthermore, the lead layer for the positive electrode and the lead layer for the negative electrode are directly joined inside a plurality of through holes formed in the substrate. That is, the lead-acid battery described in Patent Document 1 is a bipolar lead-acid battery in which a substrate having through holes (communication holes) for communicating one surface side and the other surface side and cell members are alternately stacked in a plurality.

[0005] The cell member has a positive electrode provided with a positive electrode active material layer on a lead layer for the positive electrode, a negative electrode provided with a negative electrode active material layer on a lead layer for the negative electrode, and an electrolyte layer interposed between the positive electrode and the negative electrode. The lead layer for the positive electrode of one cell member and the lead layer for the negative electrode of the other cell member are immersed and joined inside the perforation of the substrate, whereby the cell members are connected in series.

[0006] Furthermore, regarding the positive electrode active material layer of the lead-acid battery, for example, even when the amount of the positive electrode active material layer used is reduced, a technique that is excellent in low-temperature high-rate discharge performance and can suppress the reduction of the electrolyte is disclosed in Patent Document 2 below. In the technique disclosed in Patent Document 2, by using a positive electrode active material layer containing PbO2 and setting the ratio of the peak intensities of the X-ray diffraction patterns of α-PbO2 and β-PbO2 specified by wide-angle X-ray diffraction within a specific range, it is dealt with. Thus, various measures have been taken focusing on PbO2 in the positive electrode active material layer in order to improve the performance of the lead-acid battery.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Regarding the measure using PbO2 contained in the positive electrode active material layer disclosed in Patent Document 2 described above, the target is a flooded lead-acid battery. However, in terms of using the positive electrode active material layer, the bipolar lead-acid battery is the same, and it is important to avoid a decrease in the battery performance of the bipolar lead-acid battery when using a positive electrode active material layer containing PbO2.

[0009] That is, in a bipolar lead-acid battery, a structure in which an active material layer is applied to a flat sheet is often adopted, and only one surface of the active material layer contacts the current collector for the positive electrode or the current collector for the negative electrode. However, in the case of such a structure, the adhesion between the active material layer and the current collector for the positive electrode or the current collector for the negative electrode inevitably decreases, and for example, there is a possibility that the electrolyte may penetrate between the positive electrode active material layer and the current collector for the positive electrode. And when such a phenomenon occurs, it may lead to a decrease in the performance of the bipolar lead-acid battery as a whole.

[0010] An object of the present invention is to provide a bipolar lead-acid battery capable of improving the battery life while maintaining the capacity required for the battery by ensuring the adhesion between the positive electrode active material layer and the positive electrode current collector when using a positive electrode active material layer containing PbO2.

Means for Solving the Problems

[0011] The bipolar lead-acid battery according to one aspect of the present invention includes a positive electrode active material layer, a negative electrode active material layer, a current collector made of lead or a lead alloy that contacts one or both of the positive electrode active material layer and the negative electrode active material layer, and a separator disposed between the positive electrode active material layer and the negative electrode active material layer facing each other. The positive electrode active material layer has a first surface layer on the current collector side and a second surface layer on the separator side, and the content of α-PbO2 contained in the first surface layer is larger than the content of α-PbO2 contained in the second surface layer.

Effects of the Invention

[0012] According to the bipolar lead-acid battery according to one aspect of the present invention, there are provided a positive electrode active material layer, a negative electrode active material layer, a current collector made of lead or a lead alloy that is in contact with one or both of the positive electrode active material layer and the negative electrode active material layer, and a separator disposed between the positive electrode active material layer and the negative electrode active material layer facing each other. The positive electrode active material layer has a first surface layer on the current collector side and a second surface layer on the separator side, and the content of α-PbO2 contained in the first surface layer is larger than the content of α-PbO2 contained in the second surface layer. By adopting such a configuration, when a positive electrode active material layer containing PbO2 is used, the adhesion between the positive electrode active material layer and the positive electrode current collector is ensured, so that the battery life can be improved while maintaining the capacity required for the battery.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below shows an example of the present invention. Various changes or improvements can be made to these embodiments, and forms with such changes or improvements can also be included in the present invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof. Hereinafter, a bipolar lead-acid battery will be described as an example among various storage batteries.

[0015] 〔Overall Configuration〕 First, the overall configuration of the bipolar lead-acid battery according to the embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing the structure of a bipolar lead-acid battery 1 according to the embodiment of the present invention.

[0016] The bipolar lead storage battery 1 shown in Fig. 1 has a first plate unit in which a negative electrode 110 composed of a current collector 101 and a negative electrode active material layer 103 is fixed to a flat first plate 11, and a second plate unit in which a separator 104 is fixed inside a frame-shaped second plate 12.

[0017] Also, it has a third plate unit in which a bipolar electrode 130, on one surface of which a positive electrode 120 is formed and on the other surface of which a negative electrode 110 is formed, is fixed inside a frame-shaped third plate 13, and a fourth plate unit in which a positive electrode 120 composed of a current collector 101 and a positive electrode active material layer 102 is fixed to a flat fourth plate 14.

[0018] Then, by alternately laminating the second plate unit and the third plate unit between the first plate unit and the fourth plate unit, for example, a bipolar lead storage battery 1 having a substantially rectangular parallelepiped shape is configured. The number of each of the second plate unit and the third plate unit to be laminated is set so that the storage capacity of the bipolar lead storage battery 1 becomes a desired value.

[0019] A negative electrode terminal 105 is fixed to the first plate 11, and the negative electrode 110 fixed to the first plate 11 and the negative electrode terminal 105 are electrically connected. A positive electrode terminal 106 is fixed to the fourth plate 14, and the positive electrode 120 fixed to the fourth plate 14 and the positive electrode terminal 106 are electrically connected.

[0020] The first plate 11 to the fourth plate 14 are formed of, for example, a well-known molding resin. And these first plate 11 to fourth plate 14 are fixed to each other in an appropriate manner so that the inside is in a sealed state to prevent the outflow of the electrolytic solution.

[0021] The current collector 101 is formed of, for example, lead or a lead alloy. And a positive electrode active material layer 102 is disposed on one surface of the current collector 101, and a positive electrode 120 composed of the current collector 101 and the positive electrode active material layer 102 is formed.

[0022] As shown in FIG. 1, the positive electrode active material layer 102 is disposed so as to be sandwiched between the current collector 101 and the separator 104. Therefore, the positive electrode active material layer 102 has a first surface layer 102a on the current collector 101 side and a second surface layer 102b on the separator 104 side.

[0023] On the other hand, a negative electrode active material layer 103 is disposed on the other surface of the current collector 101, and a negative electrode 110 is formed. That is, the bipolar lead-acid battery 1 shown in FIG. 1 includes a bipolar electrode 130 in which the positive electrode 120 and the negative electrode 110 are formed on both surfaces of a single current collector 101.

[0024] A bipolar electrode is an electrode having both positive and negative electrode functions with a single electrode. And the bipolar lead-acid battery 1 according to the embodiment of the present invention has a battery configuration in which cell members are connected in series by alternately stacking and assembling a plurality of cell members in which a separator 104 is interposed between the positive electrode 120 and the negative electrode 110.

[0025] The separator 104 is composed of, for example, a glass fiber mat impregnated with an electrolytic solution containing sulfuric acid. And in the cell member, the positive electrode active material layer 102, the separator 104, and the negative electrode active material layer 103 are laminated in this order.

[0026] As shown in FIG. 1, a second plate including a separator 104 and a third plate including a bipolar electrode 130 are alternately stacked. Therefore, as shown in FIG. 1, the bipolar electrode 130 is disposed so as to be sandwiched between the separators 104, 104. In other words, the separator 104 is disposed so as to be sandwiched between a plurality of current collectors 101. That is, among the plurality of current collectors 101, the positive electrode active material layer 102 is in contact with one current collector 101, and the negative electrode active material layer 103 is in contact with the other current collector 101. Therefore, the positive electrode active material layer 102 and the negative electrode active material layer 103 are disposed at positions facing each other with the separator 104 interposed therebetween.

[0027] The positive electrode active material layer 102 in the embodiment of the present invention contains PbO2. When the electrolyte contained in the separator 104 comes into contact with the positive electrode active material layer 102, α-PbO2 having weak activity with respect to the electrochemical reaction and β-PbO2 having active electrochemical reaction are generated. In this case, if a large amount of α-PbO2 is present in the region where the positive electrode active material layer 102 and the separator 104 are in contact (the second surface layer 102b described above), the performance of the battery may not be sufficiently exhibited due to the properties of the α-PbO2 described above. Therefore, in the second surface layer 102b of the positive electrode active material layer 102 in contact with the separator 104, it is preferable that more β-PbO2 is present.

[0028] On the other hand, the first surface layer 102a of the positive electrode active material layer 102 is in contact with the current collector 101. As described above, in the bipolar lead storage battery 1 in the embodiment of the present invention, it is necessary to enhance the adhesion between the positive electrode active material layer 102 and the current collector 101. Therefore, in the first surface layer 102a of the positive electrode active material layer 102, it is preferable that more α-PbO2 is contained, which plays a role of improving the adhesion between the positive electrode active material layer 102 and the current collector 101.

[0029] That is, when formed, a corrosion layer and a dense layer are formed on the current collector (for example, the surface of a lead foil) and the interface of the active material layer, and these layers strengthen the adhesion between the active material layer and the current collector. This is because the corrosion layer is formed by the corrosion of the current collector surface, and the dense layer is an amorphous layer present on the surface of the active material layer, and both are considered to be substances derived from α-PbO2.

[0030] Therefore, when looking at the content of α-PbO2 in the first surface layer 102a and the second surface layer 102b of the positive electrode active material layer 102, it is preferable that more α-PbO2 is contained in the first surface layer 102a than in the second surface layer 102b.

[0031] Here, FIG. 2 is a table showing the results of a test regarding the content of α-PbO2 in the positive electrode active material layer 102 in the bipolar lead storage battery 1 according to the embodiment of the present invention. The test here is performed, for example, as follows.

[0032] That is, first, water is added to, for example, lead powder as a raw material of the positive electrode active material layer to prepare a paste. Specifically, for example, first, the lead powder and various additives are dry-mixed, water is added and wet-mixed, and then dilute sulfuric acid is added and kneaded. Then, aging and drying are performed under predetermined conditions to obtain an unformed paste. And the density of the paste after the drying is measured. Alternatively, lead red (Pb3O4) may be added to the above-described lead powder to prepare a paste. In each comparative example and each example shown in FIG. 2, pastes are prepared in various modes with and without lead red.

[0033] Then, the surfaces of the first surface layer 102a side disposed on the current collector 101 side and the second surface layer 102b side disposed on the separator 104 side of the prepared paste are scraped. When scraping the surface, for example, sandpaper was used. And the content of α-PbO2 is measured for the powder obtained by scraping by X-ray diffraction method (XRD).

[0034] Also, the paste thus prepared was used as the positive electrode active material layer 102, and the "10-hour capacity (Ah)" and the "life cycle (number of times)" were measured. The former "10-hour capacity (Ah)" is the capacity when discharging a 6V bipolar lead-acid battery with a rated capacity of 50Ah until the voltage reaches 5.4V at a current of 5A under the temperature condition of 25°C.

[0035] On the other hand, for the latter "life cycle (number of times)", under the temperature condition of 25°C, after discharging at 11.5A for 2.3 hours, constant current constant voltage charging (CC-CV charging) is carried out at 11.5A until the charging rate reaches 104% of the discharged capacity and at a constant voltage value of 7.35V. And this is regarded as one cycle, and the number of cycles when repeating until the lower limit voltage during discharge reaches 5.4V is shown.

[0036] In the table shown in Figure 2, the test results are shown for a total of 14 examples, including 7 comparative examples from Comparative Example 1 to Comparative Example 7 and 7 examples from Example 1 to Example 7 for the examples. And for each of them, first, the "relationship between the amounts of α-PbO2 present in the first surface layer 102a and the second surface layer 102b" is shown. Here, simply, the amounts of α-PbO2 in the first surface layer 102a and the second surface layer 102b are represented by inequality signs.

[0037] And then, three items are listed: the "amount of α-PbO2 (wt%) present in the first surface layer 102a", the "amount of α-PbO2 (wt%) present in the second surface layer 102b", and the "amount of α-PbO2 present in the first surface layer 102a / amount of α-PbO2 present in the second surface layer 102b". These are the numerical representations and ratios of the amounts of α-PbO2 in the first surface layer 102a and the second surface layer 102b, which were initially shown by inequality signs.

[0038] The test results for each of the comparative examples and the examples are shown for "10-hour (10HR) capacity (Ah)" and "life cycle (number of cycles)". Although the results for each comparative example and example are shown, all the tests for Comparative Example 1 are indicated by "×". This indicates that for Comparative Example 1, although the tests were conducted, no results could be obtained.

[0039] The "Comprehensive Evaluation" is an evaluation made in view of the test results of two items, namely, "10-hour (10HR) capacity (Ah)" and "life cycle (number of cycles)". Here, a capacity of less than 50 Ah for 10 hours or a life cycle of less than 5,000 cycles is indicated as "not acceptable".

[0040] Also, when the 10-hour capacity is 50 Ah or more and less than 53 Ah and the life cycle is 5,000 cycles or more, it is rated as "acceptable", and when the 10-hour capacity is 53 Ah or more and the life cycle is 5,000 cycles or more, it is evaluated as "good".

[0041] The composition of the positive electrode active material layer 102 used in each comparative example and example is described in the "Specifications". As described above, the presence or absence of red lead differs between the comparative examples and the examples. Also, even when red lead is included, the content is divided into three patterns: 5%, 10%, and 15%. Note that the numerical value of the content indicates the amount of red lead in the total weight of the resulting paste.

[0042] Also, in Comparative Examples 5 to 7, pastes were manufactured such that the density of the dried paste (described as "dry paste" in the table) differed between the first surface layer 102a (described as "foil side" in the table) and the second surface layer 102b (described as "separator side" in the table), and these pastes were combined and used as a single positive electrode active material layer 102. In the other comparative examples and examples, pastes having the same density as a whole were used as the positive electrode active material layer 102.

[0043] Looking at the relationship between the amounts of α-PbO₂ present in the first surface layer 102a and the second surface layer 102b, which is the first item in the table, in Comparative Examples 1 to 7, except for Comparative Examples 2 to 4, the content of α-PbO₂ is said to be less in the first surface layer 102a than in the second surface layer 102b. On the other hand, in Comparative Example 2, the content of α-PbO₂ is the same in both the first surface layer 102a and the second surface layer 102b. Also, in Comparative Examples 3 and 4, the content of α-PbO₂ contained in the first surface layer 102a is more than the content of α-PbO₂ contained in the second surface layer 102b.

[0044] However, the overall evaluation for any of Comparative Examples 1 to 7 is "not acceptable". This is because either one or both of the test results of "10-hour (10HR) capacity (Ah)" and "life cycle (number of times)" do not meet the above-mentioned preset criteria. For example, in Comparative Examples 6 and 7, although the result of "life cycle (number of times)" is a good result even including other comparative examples or examples, the "10-hour (10HR) capacity (Ah)" is low.

[0045] Also, looking at Comparative Examples 3 and 4 where the content of α-PbO₂ contained in the first surface layer 102a is set to be more than the content of α-PbO₂ contained in the second surface layer 102b, in Comparative Example 3, the "life cycle (number of times)" does not reach the standard, and in Comparative Example 4, the "10-hour (10HR) capacity (Ah)" does not meet the standard.

[0046] Here, in Comparative Example 3, by adjusting the density of the dried paste and the addition amount of red lead, β-PbO2 is likely to be generated overall. Therefore, the active material layer like that of Comparative Example 3 has a large specific surface area and many pores through which the electrolyte penetrates. Thus, as described above, the value of "10-hour (10HR) capacity (Ah)" is good, but on the other hand, the "life cycle (performance)" deteriorates. Therefore, even if the content of α-PbO2 in the first surface layer 102a is more than that in the second surface layer 102b, if the content of α-PbO2 present in the first surface layer 102a is not within a predetermined range as in each of the examples, the "life cycle (performance)" will deteriorate.

[0047] On the other hand, for Comparative Example 4, due to its specifications, the density of the dried paste is high and the particle structure is such that sulfuric acid hardly penetrates. Such an active material layer has a generally higher content of α-PbO2 compared to, for example, other comparative examples and examples. However, as described above, even if the content of α-PbO2 in the first surface layer 102a is more than that in the second surface layer 102b, if the content of α-PbO2 present in the first surface layer 102a is not within a predetermined range (too much as opposed to Comparative Example 3), conversely, there is less β-PbO2 contributing to the charge-discharge reaction and the "10-hour (10HR) capacity (Ah)" does not meet the standard.

[0048] In contrast, in Examples 1 to 7, the content of α-PbO2 in the first surface layer 102a is made to be more than the content of α-PbO2 in the second surface layer 102b in each case.

[0049] Looking at each of these Examples 1 to 7, the overall evaluations of Examples 1 to 4 are all "fair". On the other hand, for Examples 5 to 7, the overall evaluations are all "good".

[0050] Comparing the examples with a "Fair" overall evaluation and those with a "Good" overall evaluation, it can be seen that all the examples with a "Good" overall evaluation have obtained good results particularly in the test of "10-hour (10HR) capacity (Ah)". Also, when confirming the difference depending on the presence or absence of red lead in Examples 2 to 4 having the same paste density, it is found that as the positive electrode active material layer 102, it is better to contain red lead for obtaining better results regarding "10-hour (10HR) capacity (Ah)".

[0051] This is because β-PbO2 is more effective in ensuring the capacity of the bipolar lead-acid battery 1, and as the content of red lead contained in the active material layer increases, β-PbO2 is more easily generated than α-PbO2.

[0052] Also, Examples 5 to 7 all have a "Good" overall evaluation. However, focusing on the paste density, it can be seen that the higher the density, the better the results for "10-hour (10HR) capacity (Ah)" and "life cycle (number of times)". This indicates that as the paste density increases, the content of α-PbO2 increases, so the life cycle also extends, and a bipolar lead-acid battery 1 with a good balance between capacity can be obtained.

[0053] From the above test results, it is possible to obtain better effects when the content of α-PbO2 contained in the first surface layer 102a is more than the content of α-PbO2 contained in the second surface layer 102b. And from the test results of Examples 1 to 7, the content of α-PbO2 contained in the first surface layer 102a is preferably 10 wt% or more and 30 wt% or less with respect to the total amount of the material constituting the first surface layer 102a. Furthermore, it is more preferable that the content of α-PbO2 contained in the first surface layer 102a is 2 times or more and 10 times or less the content of α-PbO2 contained in the second surface layer 102b.

[0054] Note that the content of α-PbO2 contained in the first surface layer 102a being 10 wt% or more and 30 wt% or less is with respect to the total amount of the powder obtained by scraping off the active material layer constituting the first surface layer 102a. The same applies to the second surface layer 102b.

[0055] By adopting the configuration described above, when using a positive electrode active material layer containing PbO2, it is possible to improve the battery life while maintaining the capacity required for the battery by ensuring the adhesion between the positive electrode active material layer and the positive electrode current collector.

[0056] In particular, by controlling the content of α-PbO2 contained in the positive electrode active material layer to be higher on the side in contact with the current collector than on the side in contact with the separator, it is possible to prevent the shortening of the battery life caused by the separation between the current collector and the positive electrode active material layer while maintaining the capacity of the bipolar lead-acid battery.

[0057] So far, the bipolar lead-acid battery 1 in which the positive electrode active material layer 102 and the negative electrode active material layer 103 are provided on both sides of a single current collector 101 has been described as an example. However, instead of the bipolar lead-acid battery 1 in such a form, for example, a positive electrode having a positive electrode current collector and a positive electrode active material layer, a negative electrode having a negative electrode current collector and a negative electrode active material layer, and a separator interposed between the positive electrode and the negative electrode, and a cell member laminated with a space therebetween, and a substrate that forms a plurality of spaces for individually accommodating the plurality of cell members and covers at least one of the positive electrode side and the negative electrode side of the cell member, and a frame body that surrounds the side surface of the cell member, and a space forming member including the same, and a through hole provided through the substrate, and a conductor inserted into the through hole for achieving electrical connection between the positive electrode side and the negative electrode side may also be used.

[0058] Furthermore, so far, the description has been made on the premise that the positive electrode active material layer 102 is a single (integral) active material layer, but it is not necessarily required to have such a configuration. For example, an active material layer containing more α-PbO2 and an active material layer having a lower content of α-PbO2 than the said active material layer are prepared, and these two active material layers are combined into one positive electrode active material layer. And it is also good to arrange the former on the side of the current collector 101 and the latter on the side of the separator 104.

[0059] Furthermore, as described above, when using a plurality of active material layers with different contents of α-PbO2 stacked on top of each other, the thicknesses of the plurality of active material layers (the length in the direction of the distance between the current collector and the separator. The length of the horizontal active material layer in the bipolar lead-acid battery 1 shown in FIG. 1) do not necessarily have to be uniform.

Explanation of symbols

[0060] 1 ··· Bipolar lead-acid battery 11 ··· First plate 12 ··· Second plate 13 ··· Third plate 14 ··· Fourth plate 101 ··· Current collector 102 ··· Positive electrode active material layer 102a ··· First surface layer 102b ··· Second surface layer 103 ··· Negative electrode active material layer 104 ··· Separator 105 ··· Negative electrode terminal 106 ··· Positive electrode terminal 110 ··· Negative electrode 120 ··· Positive electrode 130 ··· Bipolar electrode

Claims

1. a positive electrode active material layer, a negative electrode active material layer, a current collector made of lead or a lead alloy that is in contact with one or both of the positive electrode active material layer or the negative electrode active material layer, a separator disposed between the positive electrode active material layer and the negative electrode active material layer facing each other, and the positive electrode active material layer has a first surface layer on the current collector side and a second surface layer on the separator side, The content of α-PbO contained in the first surface layer ２ is more than the content of α-PbO ２ contained in the second surface layer, and the bipolar lead storage battery is characterized by this.

2. The α-PbO contained in the first surface layer ２ The bipolar lead-acid battery according to claim 1, wherein the content thereof is 10 wt% or more and 30 wt% or less.

3. The content of α-PbO contained in the first surface layer ２ is at least twice and at most ten times the content of α-PbO ２ contained in the second surface layer, and the bipolar lead storage battery according to claim 1 or claim 2 is characterized by this.

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