Flooded lead-acid battery

Abstract

Provided is a flooded lead-acid battery in which the difference in chemical conversion efficiency between a positive electrode plate and a negative electrode plate is reduced by increasing the chemical conversion efficiency of the positive electrode plate, and the amount of chemical conversion electricity required for sufficient progress of chemical conversion is reduced. The flooded lead-acid battery comprises an electrode plate group and an electrolyte. The electrode plate group is housed in a cell chamber together with an electrolyte and has a laminate. The laminate comprises a plurality of positive electrode plates (10) and negative electrode plates (20) that are alternately arranged, and separators (30) that are arranged between the positive electrode plates and the negative electrode plates. The positive electrode plates (10) include a positive electrode current collector plate and a positive electrode mixture held by a grid portion of the positive electrode current collector plate. The negative electrode plates (20) include a negative electrode current collector plate and a negative electrode mixture held by a grid portion of the negative electrode current collector plate. The thickness of the positive electrode current collector plate is smaller than the thickness of the negative electrode current collector plate, and the distance (W) between the positive electrode plate (10) and the negative electrode plate (20) is 0.4 to 1.0 mm inclusive.

Description

Flooded lead-acid battery

[0001] The present invention relates to a flooded lead-acid battery.

[0002] A flooded lead-acid battery, which is a general lead-acid battery, includes a battery case having cell chambers, electrode plate groups housed in the cell chambers, and an electrolytic solution injected into the cell chambers. The electrode plate group has a laminate including a plurality of alternately arranged positive plates and negative plates, and a separator disposed between the positive plates and the negative plates. The positive plate has a positive current collector plate including a grid portion, a positive ear portion protruding upward in the vertical direction of the battery case from the grid portion, and a positive mixture (a mixture containing a positive active material) held in the grid portion. The negative plate has a negative current collector plate including a grid portion, a negative ear portion protruding upward in the vertical direction of the battery case from the grid portion, and a negative mixture held in the grid portion.

[0003] The positive ear portion is arranged at a position offset to one side from the center in the width direction of the grid portion (the direction along the direction perpendicular to both the vertical direction of the battery case and the lamination direction of the laminate), and the negative ear portion is arranged at a position offset to the other side from the center in the width direction of the grid portion. The electrode plate group further has a positive strap and a negative strap that connect the ear portions of the plurality of positive plates and negative plates respectively. Dilute sulfuric acid is used as the electrolytic solution. Such flooded lead-acid batteries are widely used as automotive batteries and the like.

[0004] In the production of a flooded lead-acid battery, an electrode plate group including a laminate produced using a positive paste board (positive plate before formation) and a negative paste board (negative plate before formation) is housed in a cell chamber, and a formation step of energizing in dilute sulfuric acid is performed. Through this formation step, the positive paste board and the negative paste board are made into the positive plate and the negative plate. Regarding the formation step, in recent years, from the viewpoints of soaring electricity costs and the environmental impact of carbon dioxide emissions, reduction of the amount of electricity during formation, that is, improvement of formation efficiency has been required. In addition, regarding the thickness of the positive current collector plate and the negative current collector plate in a conventional flooded lead-acid battery, as described in the examples of Patent Document 1, the thickness of the positive current collector plate is made larger than the thickness of the negative current collector plate.

[0005] Japanese Unexamined Patent Publication No. 2001-068117

[0006] In typical liquid lead-acid batteries, the positive electrode plate has a lower chemical conversion efficiency than the negative electrode plate. Furthermore, as mentioned above, in conventional liquid lead-acid batteries, the positive electrode current collector plate is made thicker than the negative electrode current collector plate. In lead-acid batteries with such a configuration, the difference in chemical conversion efficiency between the positive and negative electrode plates becomes even larger, requiring a larger amount of electricity to sufficiently convert the positive electrode plate. The object of the present invention is to provide a liquid lead-acid battery in which the chemical conversion efficiency of the positive electrode plate is increased, thereby reducing the difference in chemical conversion efficiency between the positive and negative electrode plates and reducing the amount of electricity required for sufficient conversion.

[0007] A first aspect of the present invention for solving the above problems is a liquid lead-acid battery having the following configuration (1) to (4): (1) A group of electrode plates and an electrolyte, the group of electrode plates being housed together with the electrolyte in a cell chamber, the group of electrode plates having a laminate consisting of alternately arranged negative electrode plates and positive electrode plates, and a separator placed between the negative electrode plate and the positive electrode plate. (2) The positive electrode plate has a positive electrode current collector plate and a positive electrode mixture held on the positive electrode current collector plate. The negative electrode plate has a negative electrode current collector plate and a negative electrode mixture held on the negative electrode current collector plate. (3) The thickness of the positive electrode current collector plate is less than the thickness of the negative electrode current collector plate. (4) The distance between adjacent positive electrode plates and negative electrode plates is 0.4 mm or more and 1.0 mm or less.

[0008] According to the present invention, by increasing the chemical conversion efficiency of the positive electrode plate, the difference in chemical conversion efficiency between the positive electrode plate and the negative electrode plate is reduced, and it is expected that a liquid lead-acid battery will be provided in which the amount of chemical conversion electricity required to sufficiently advance the chemical conversion is reduced.

[0009] This diagram illustrates an embodiment of a liquid lead-acid battery, showing the battery case with the lid removed as viewed from above. This is a partial cross-sectional view of the liquid lead-acid battery of the embodiment, including the inter-cell connection portion, as viewed from the front (long side). This is a cross-sectional view showing a set of positive electrode plates, separators, and negative electrode plates constituting the laminate of the liquid lead-acid battery of the embodiment. This is a front view of the laminate constituting the liquid lead-acid battery of the embodiment, showing the arrangement of the grid-like portion of the positive electrode current collector plate and the grid-like portion of the negative electrode current collector plate within the laminate. This is a plan view of the laminate constituting the liquid lead-acid battery of the embodiment, showing the arrangement of the grid-like portion of the positive electrode current collector plate, the separator, and the grid-like portion of the negative electrode current collector plate within the laminate, and the distance between the electrode plates.

[0010] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments shown below. The embodiments shown below have technically preferred limitations for carrying out the present invention, but these limitations are not essential requirements of the present invention.

[0011] [Overall Battery Configuration] As shown in Figure 1, the liquid lead-acid battery of this embodiment has a monoblock type battery case 1 and six electrode plate groups 3 housed in each cell chamber 4. The battery case 1 is rectangular in shape and has a pair of first walls 11 formed on a pair of long sides of the rectangle that forms the bottom surface, and a pair of second walls 12 formed on a pair of short sides. The inside of the battery case 1 is divided into six cell chambers 4 by five partition walls 13 parallel to the second walls 12. Each of the six cell chambers 4 houses one electrode plate group 3 and is filled with electrolyte. The electrolyte is dilute sulfuric acid containing aluminum ions at a concentration of 0.02 mol / L or more and 0.2 mol / L or less. As shown in Figure 1, the arrangement direction of the cell chambers 4 is the X direction (long side of the battery case 1), and the direction perpendicular to this is the Y direction (short side of the battery case 1).

[0012] As shown in Figure 2, each electrode plate group 3 has a laminate 6. The laminate 6 is composed of a plurality of alternatingly arranged positive electrode plates 10 and negative electrode plates 20, and a separator 30 placed between the positive electrode plates 10 and the negative electrode plates 20. The number of negative electrode plates 20 constituting the laminate 6 is one more than the number of positive electrode plates 10. As shown in Figure 3, the positive electrode plate 10 is composed of a positive electrode current collector plate 101 and a positive electrode mixture (a mixture containing positive electrode active material) 102. The positive electrode current collector plate 101 has a rectangular grid-like portion 101a and an ear portion 101b protruding from one side of the rectangle forming the grid-like portion 101a.

[0013] The positive electrode mixture 102 is held in the lattice-like portion 101a. The positive electrode mixture 102 is filled into the openings of the lattice-like portion 101a and also exists in layers on both plate surfaces of the lattice-like portion 101a. In Figure 3, only the positive electrode mixture 102 formed in layers is shown. In Figure 2, the lattice-like portion 101a in which the positive electrode mixture 102 is held is indicated by reference numeral 111.

[0014] The lugs 101b of the positive electrode plate 10 are positioned offset to one side from the center in the width direction (the direction perpendicular to the plane of the paper in Figures 2 and 3) of the grid-like portion 101a. The negative electrode plate 20 is composed of a negative electrode current collector plate 201 and a negative electrode mixture (a mixture containing a negative electrode active material) 202. The negative electrode current collector plate 201 has a rectangular grid-like portion 201a, lugs 201b protruding from one side (upper frame bone) of the rectangle forming the grid-like portion 201a, and feet 201c protruding downward from the lower frame bone.

[0015] The negative electrode mixture 202 is held in the grid-like portion 201a. The negative electrode mixture 202 is filled into the openings of the grid-like portion 201a and also exists in layers on both plate surfaces of the grid-like portion 201a. In Figure 3, only the negative electrode mixture 202 formed in layers is shown. In Figure 2, the grid-like portion 201a in which the negative electrode mixture 202 is held is indicated by reference numeral 211. The tabs 201b of the negative electrode plate 20 are positioned offset from the center in the width direction of the grid-like portion (the direction perpendicular to the plane of the paper in Figures 2 and 3). The separator 30 is made of porous polyethylene, and as shown in Figure 3, the positive electrode plate 10 is housed in a bag-shaped separator 301.

[0016] As shown in Figures 1 and 2, each electrode plate group 3 further includes a positive electrode strap 71 and a negative electrode strap 72 connecting electrode plates of the same polarity, and in those housed in cells at both ends, a positive electrode intermediate pole 71a and a negative electrode intermediate pole 72a rising from the positive electrode strap 71 and the negative electrode strap 72, respectively. The positive electrode strap 71 and the negative electrode strap 72 connect the tabs 101b of the multiple positive electrode plates 10 and the tabs 201b of the negative electrode plates 20 that constitute the laminate 6 at different positions in the width direction of the positive electrode plates 10 and the negative electrode plates 20 (the direction that becomes the Y direction when housed in the cell chamber).

[0017] The electrode plate groups 3 housed in the cell chambers 4 located at both ends in the cell arrangement direction each have a positive terminal pole 8 and a negative terminal pole 9, which serve as external terminals. The positive terminal pole 8 and the negative terminal pole 9 are formed on the positive strap 71 and the negative strap 72 via small pieces 71b and 72b, respectively. Each electrode plate group 3 is housed in the cell chamber 4 with the stacking direction of the laminate 6 aligned with the X direction, and the plate surfaces of the positive electrode plate 10 and the negative electrode plate 20 aligned with the vertical direction of the cell chamber 4. The positive intermediate pole 71a and the negative intermediate pole 72a of adjacent cell chambers 4 are resistance welded, electrically connecting adjacent cells in series. Furthermore, the tops of all cell chambers 4 are sealed by fixing a lid (not shown) to the battery case 1. The positive terminal pole 8 and the negative terminal pole 9 penetrate the lid and are exposed to the outside.

[0018] [Regarding the positive electrode plate, negative electrode plate, and inter-plate distance] The positive electrode current collector plate 101 constituting the positive electrode plate 10 is a stamped product made from a rolled sheet of lead alloy. The thickness of the positive electrode current collector plate 101 is 0.8 mm or more and 1.2 mm or less. The grid-like portion 101a of the positive electrode current collector plate 101 is rectangular. The negative electrode current collector plate 201 constituting the negative electrode plate 20 is a cast product made of lead alloy. The grid-like portion 201a of the negative electrode current collector plate 201 is rectangular. The thickness of the positive electrode current collector plate 101 is less than the thickness of the negative electrode current collector plate 201. The ratio of the thickness of the positive electrode current collector plate 101 to the thickness of the negative electrode current collector plate 201 is, for example, 0.8 or more and less than 1.0.

[0019] As shown in Figure 4, when the positive electrode current collector plate 101 and the negative electrode current collector plate 201 are stacked on top of each other, the grid-like portion 101a of the positive electrode current collector plate 101 is located outside the outer periphery of the grid-like portion 201a of the negative electrode current collector plate 201. In other words, the apparent flat area of ​​the grid-like portion 101a of the positive electrode current collector plate 101 (the product of the dimension in the direction in which the tabs 101b of the grid-like portion 101a extend (height) and the dimension in the direction perpendicular to it (width)) is larger than the apparent flat area of ​​the grid-like portion 201a of the negative electrode current collector plate 201 (the product of the dimension in the direction in which the tabs 201b of the grid-like portion 201a extend (height) and the dimension in the direction perpendicular to it (width)).

[0020] As shown in Figure 5, the separator 30 is a ribbed separator comprising a flat base 31 and ribs 32 protruding from the back surface of the base 31, and is formed as a bag-shaped separator 301. The ribs 32 are arranged at equal intervals in the width direction of the base 31 and extend along the length direction (depth direction of the battery case). In other words, the ribs 32 are longitudinal ribs. The distance between adjacent positive electrode plates 10 and negative electrode plates 20, i.e., the inter-plate distance W, is substantially equal to the thickness of the separator 30. In the case of a ribbed separator, the thickness of the separator 30 is the sum of the thickness of the base 31 and the protrusion dimension of the ribs 32 from the base 31.

[0021] Furthermore, in the liquid lead-acid battery of this embodiment, the thickness of the separator 30 is 0.4 mm or more and 1.0 mm or less. In other words, the distance W between the plates in the laminate constituting the liquid lead-acid battery of this embodiment is 0.4 mm or more and 1.0 mm or less. The distance W between the plates does not change when the laminate 6 is housed in the cell chamber 4 and subjected to surface pressure, or when it is removed from the cell chamber 4 and exposed to atmospheric pressure. A conventionally known method can be used for manufacturing the liquid lead-acid battery of this embodiment.

[0022] [Function and Effects] In the liquid lead-acid battery of this embodiment, the thickness of the positive electrode current collector plate is 0.8 mm or more and 1.2 mm or less, and less than or equal to the thickness of the negative electrode current collector plate, the ratio of the thickness of the positive electrode current collector plate to the thickness of the negative electrode current collector plate is 0.8 or more and less than 1.0, and the distance W between the electrodes is 0.4 mm or more and 1.0 mm or less. First, because the thickness of the positive electrode current collector plate is less than or equal to the thickness of the negative electrode current collector plate, the balance of the chemical state between the positive electrode plate and the negative electrode plate is better compared to the case where the thickness of the positive electrode current collector plate is greater than the thickness of the negative electrode current collector plate, and the overall chemical conversion efficiency is improved. Therefore, the amount of chemical conversion electricity required to sufficiently advance the chemical conversion can be reduced, and the cost related to chemical conversion can be reduced.

[0023] Furthermore, since the ratio of the thickness of the positive electrode current collector to the thickness of the negative electrode current collector is 0.8 or more and less than 1.0, the chemical conversion efficiency of the positive electrode plate is further improved compared to cases where this ratio falls outside this range. Moreover, by having a thickness of 0.8 mm or more and 1.2 mm or less of the positive electrode current collector, the current collection efficiency of the positive electrode plate in the chemical conversion process is particularly high, and the chemical conversion efficiency of the positive electrode plate is particularly improved. In addition, in the liquid lead-acid battery of this embodiment, dilute sulfuric acid containing aluminum ions at a concentration of 0.02 mol / L or more and 0.2 mol / L or less is used as the electrolyte. Compared to the case where dilute sulfuric acid that does not contain aluminum ions within the above concentration range is used, the crystals of lead sulfate in the electrode plate produced in the chemical conversion process are made non-uniform, and the reaction from lead sulfate to lead oxide is promoted, thereby improving the chemical conversion efficiency.

[0024] Furthermore, when the inter-plate distance W is between 0.4 mm and 1.0 mm, the effect of suppressing dendrite shorts is enhanced, and the conversion efficiency can be improved, compared to when the inter-plate distance W falls outside this range. In particular, if the inter-plate distance W is less than 0.4 mm, not only will dendrite shorts occur, but the discharge performance and conversion efficiency will also be low. Also, if the inter-plate distance W exceeds 1.0 mm, sufficient discharge performance and conversion efficiency may not be obtained.

[0025] [Preparation of Test Batteries] Samples No. 1 to No. 27 were prepared as liquid lead-acid batteries with the same structure as the liquid lead-acid battery of the embodiment, with the configurations shown below. Samples No. 1 to No. 27 are B24 size liquid lead-acid batteries with a nominal voltage of 12V, and all configurations are the same except for changes in the thickness of the positive electrode current collector plate, the thickness of the negative electrode current collector plate, the distance between the electrodes W, the aluminum ion content of the electrolyte, and the ratio of the total compound charge to the theoretical capacity of the positive electrode.

[0026] [No.1] <Manufacturing of the positive electrode plate before chemical conversion> The positive electrode current collector plate was manufactured by performing the slab casting process, rolling process, and punching process in this order. First, the slab casting process was carried out using the following method. A block of lead alloy consisting of 0.06 mass% Ca, 1.6 mass% Sn, 0.02 mass% Al, and the remainder being lead and unavoidable impurities was prepared and melted by heating to obtain molten metal. This molten metal was poured between two opposing metal rolls and cooled by the metal rolls to obtain a lead alloy slab. Next, the obtained lead alloy slab was passed between a pair of upper and lower rolling rolls to perform a rolling process at a reduction ratio of 90% to obtain a rolled sheet with a width of 320 mm and a thickness of 1.2 mm. Next, the obtained rolled sheet was put through a press molding machine and punched out in the thickness direction to obtain a positive electrode current collector plate 101 in which the ear portion 101b extends upward from the upper frame bone of the lattice portion 101a.

[0027] The dimensions of the grid-like portion 101a are 113.0 mm in the direction in which the ear portion 101b extends (height), 105.0 mm in the direction perpendicular to it (width), and 1.2 mm in thickness. The estimated flat area of ​​the grid-like portion 101a is 113.0 × 105.0 = 11865 mm². 2 The dimensions of the ear portion 101b are 10 mm in width and 15 mm in height. The ear portion 101b extends from between the widthwise center and one end (the right end in Figure 4) of the grid-like portion 101a. After filling the grid-like portion 101a of the obtained positive electrode current collector plate with a positive electrode paste prepared by a conventional method, it was matured and dried by a conventional method to obtain a positive electrode plate (positive electrode filled plate) 10 before chemical formation.

[0028] <Manufacturing of the negative electrode plate before chemical conversion> Using a lead alloy consisting of 0.09 mass% Ca, 0.4 mass% Sn, 0.02 mass% Al, and the remainder being lead and unavoidable impurities, a negative electrode current collector plate 201 was obtained by continuous casting, as shown in Figure 5, with ear portions 201b extending upward from the upper frame bone of the lattice portion 201a and foot portions 201c extending downward from the lower frame bone. The dimensions of the lattice portion 201a are 108.5 mm in the direction in which the ear portions 201b extend (height), 102.0 mm in the direction perpendicular to this (width), and 1.0 mm in thickness. The estimated flat area of ​​the lattice portion 201a is 108.5 × 102.0 = 11067 mm² 2 That is the case.

[0029] The dimensions of the ear portion 201b are 10 mm in width and 15 mm in height. The ear portion 201b extends from between the widthwise center and the other end (left end in Figure 4) of the grid-like portion 201a. After filling the grid-like portion 201a of the obtained negative electrode current collector plate with negative electrode paste prepared by the following method, the plate was matured and dried using a normal method to obtain a negative electrode plate (negative electrode filled plate) 20 before chemical formation. The negative electrode paste was prepared by adding necessary additives such as conductive carbon to lead powder, mixing them by dry mixing, then adding water and kneading, and finally adding dilute sulfuric acid to the resulting water mixture and kneading.

[0030] <Preparation of electrode plate groups before chemical conversion> As separator 30, a porous polyethylene separator with longitudinal ribs was used, and a bag-shaped separator 301 was obtained by making a bag shape with the longitudinal rib side facing inward. Specifically, a separator 30 with a thickness (sum of the thickness of the base 31 and the protruding dimension of the rib 32) of 0.7 mm was prepared. One positive electrode packed plate for each sample was placed in each bag-shaped separator. Six laminates were prepared by alternately stacking six bag-shaped separators containing positive electrode packed plates and seven negative electrode packed plates. Next, using a COS (cast-on-strap) casting apparatus, straps and intermediate electrode pillars (straps and terminal electrode pillars in cells located at both ends) were formed on the positive electrode packed plates and negative electrode packed plates of the six obtained laminates, respectively, to obtain six electrode plate groups.

[0031] <Battery Assembly> Next, the six electrode plates obtained were placed in the six cell chambers of a polypropylene monoblock type battery case. Then, resistance welding of the intermediate electrode poles between adjacent cell chambers and heat welding of the battery case and lid were performed using the usual method. Next, dilute sulfuric acid with a specific gravity of 1.240 (at 20°C) was injected into each cell chamber through the respective filling ports on the lid as the electrolyte. Finally, the filling ports were sealed with vent plugs to assemble the unformed liquid lead-acid battery.

[0032] <Formation Process> Subsequently, the battery case was reformed using a standard method until the total charge (Ah) reached 200% of the theoretical capacity of the positive electrode. This transformed the positive electrode and negative electrode filler plates into positive and negative electrode plates, completing the No. 1 liquid lead-acid battery. The amount of electricity required for this battery case reformation, i.e., the amount of reformation electricity (Ah), was recorded.

[0033] [No.2] Dilute sulfuric acid with an aluminum ion concentration of 0.1 mol / L and a specific gravity of 1.240 (at 20°C) was obtained by adding aluminum sulfate to dilute sulfuric acid, and this was used as the electrolyte. Except for this, liquid lead-acid battery No.2 was completed in the same manner as No.1. [No.3] Liquid lead-acid battery No.3 was completed in the same manner as No.2, except that the battery case was reformed until the total charge capacity (Ah) reached 170% of the theoretical capacity of the positive electrode.

[0034] [No. 4 to No. 7] Except for using negative electrode current collectors with thicknesses of 1.2 mm, 1.3 mm, 1.5 mm, and 1.7 mm, while keeping the amount of negative electrode mixture per negative electrode plate unchanged, liquid lead-acid batteries No. 4 to No. 7 were completed in the same manner as No. 3. [No. 8 to No. 12] Except for using positive electrode current collectors with a thickness of 1.0 mm and negative electrode current collectors with thicknesses of 0.8 mm, 1.0 mm, 1.1 mm, 1.3 mm, and 1.4 mm, liquid lead-acid batteries No. 8 to No. 12 were completed in the same manner as No. 3, while keeping the amount of positive electrode mixture per positive electrode plate and the amount of negative electrode mixture per negative electrode plate unchanged, positive electrode current collectors with a thickness of 1.0 mm and negative electrode current collectors with thicknesses of 0.8 mm, 1.0 mm, 1.1 mm, 1.3 mm, and 1.4 mm. [No. 13 to No. 17] Except for keeping the amount of positive electrode compound per positive electrode plate and the amount of negative electrode compound per negative electrode plate unchanged, and using a positive electrode current collector plate with a thickness of 0.8 mm and negative electrode current collector plates with thicknesses of 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, and 1.1 mm, liquid lead-acid batteries No. 13 to No. 17 were completed in the same manner as No. 3.

[0035] [No. 18-19] Except for keeping the amount of positive electrode mixture per positive electrode plate and the amount of negative electrode mixture per negative electrode plate unchanged, and using positive electrode current collector plates with thicknesses of 0.7 mm and 1.3 mm, and negative electrode current collector plates with thicknesses of 0.8 mm and 1.6 mm, liquid lead-acid batteries No. 18-19 were completed in the same manner as No. 3. [No. 20-23] Except for keeping the amount of positive electrode mixture per positive electrode plate and the amount of negative electrode mixture per negative electrode plate unchanged, and using positive electrode current collector plates with a thickness of 0.8 mm and negative electrode current collector plates with a thickness of 1.0 mm, the concentration of aluminum ions contained in the electrolyte was changed, and liquid lead-acid batteries No. 20-23 were completed in the same manner as No. 3.

[0036] [No. 24] A separator 30 with a thickness (the sum of the thickness of the base 31 and the protruding dimension of the rib 32) of 0.3 mm was used. The liquid lead-acid battery No. 24 was completed using the same method as No. 16. [No. 25] A separator 30 with a thickness (the sum of the thickness of the base 31 and the protruding dimension of the rib 32) of 0.4 mm was used. The liquid lead-acid battery No. 25 was completed using the same method as No. 16.

[0037] [No. 26] A separator 30 with a thickness (the sum of the thickness of the base 31 and the protruding dimension of the rib 32) of 1.0 mm was used. The liquid lead-acid battery No. 26 was completed using the same method as No. 16. [No. 27] A separator 30 with a thickness (the sum of the thickness of the base 31 and the protruding dimension of the rib 32) of 1.1 mm was used. The liquid lead-acid battery No. 27 was completed using the same method as No. 16. Note that the difference in the thickness of the separators 30 from No. 24 to No. 27 is due to the difference in the protruding dimension of the rib 32, while the thickness of the base 31 is the same.

[0038] [Evaluation Test] For the liquid lead-acid batteries No. 1 to No. 27 prepared in this manner, the presence or absence of dendrite shorts (DS) was checked, and then the amount of lead sulfate contained in the positive electrode plate was measured. Next, the rated cold cranking current (CCA) and 20-hour rate capacity were measured, and the average of these two values ​​was calculated as the discharge performance value. Then, the relative value [%] was calculated for the amount of chemically converted electricity recorded during chemical conversion, the amount of lead sulfate contained in the measured positive electrode plate divided by the amount of positive electrode mixture (lead sulfate content of the positive electrode plate), and the calculated discharge performance value, with the value of liquid lead-acid battery No. 1 set to 100%.

[0039] Furthermore, the relative values ​​of the amount of generated electricity, the lead sulfate content of the positive electrode plate, and the discharge performance value were judged as follows: If the amount of generated electricity is greater than 100%, it is marked "×"; if it is between 95% and 100%, it is marked "△"; if it is between 90% and 95%, it is marked "〇"; and if it is less than 90%, it is marked "◎". In other words, since the manufacturing cost increases as the value of the amount of generated electricity increases, a smaller value of the amount of generated electricity is preferable.

[0040] If the lead sulfate content of the positive electrode plate exceeds 100%, it is rated as "×"; if it is 80% or more and 100% or less, it is rated as "△"; if it is 60% or more and less than 80%, it is rated as "○"; and if it is less than 60%, it is rated as "◎". The lower the lead sulfate content contained in the positive electrode plate, the smaller the residual amount of unformed material, which indicates that the formation state of the positive electrode is favorable. That is, since it indicates that there is room to further reduce the formation electric quantity, a lower value of the lead sulfate content of the positive electrode plate is preferred. If the discharge performance value is less than 100%, it is rated as "×"; if it is 100% or more and 105% or less, it is rated as "△"; if it is more than 105% and 110% or less, it is rated as "○"; and if it exceeds 110%, it is rated as "◎". The higher the discharge performance value, the better the battery performance, which indicates that the positive electrode plate has been sufficiently formed. That is, since it indicates that there is room to further reduce the formation electric quantity, a higher discharge performance value is preferred.

[0041] Further, it was determined that a case with dendrite short-circuit was rated as "×", and a case without dendrite short-circuit was rated as "○". Furthermore, the comprehensive evaluation was performed as follows. In the "evaluation of formation electric quantity", "evaluation of lead sulfate content of positive electrode plate" and "evaluation of discharge performance value", "◎" is assigned 3 points, "○" is assigned 2 points, "△" is assigned 1 point, and "×" is assigned 0 points. In the "evaluation of dendrite short-circuit", "○" is assigned 2 points and "×" is assigned 0 points, the total score is calculated. If the total score is 11 or more, it is rated as "◎"; if it is 9 or 10, it is rated as "○"; if it is 4 or more and 8 or less, it is rated as "△"; and if it is 3 or less, it is rated as "×". The configuration of each sample, test results and their evaluations, and the comprehensive evaluation are summarized in Table 1.

[0042]

[0043] The following can be seen from the results in Table 1. In the comparison between No.1 and No.2, the positive electrode current collector plate is thicker than the negative electrode current collector plate, and the inclusion of aluminum ions in the electrolyte improves the lead sulfate content of the positive electrode and the discharge performance. In the comparison between No.2 and No.3, when the positive electrode current collector plate is thicker than the negative electrode current collector plate, the total charge amount during tank formation is changed from 200% to 170% of the positive electrode theoretical capacity ratio, which deteriorates the lead sulfate content of the positive electrode and the discharge performance.

[0044] In the comparison of No. 3 to No. 7, when the positive electrode current collector plate is 1.2 mm, the comprehensive evaluation varies depending on the thickness of the negative electrode current collector plate, and the comprehensive evaluation is particularly high when the ratio of the thickness of the positive electrode current collector plate to the negative electrode current collector plate is 0.8 and 0.9. In the comparison of No. 8 to No. 12, when the positive electrode current collector plate is 1.0 mm, the comprehensive evaluation varies depending on the thickness of the negative electrode current collector plate, and the comprehensive evaluation is particularly high when the ratio of the thickness of the positive electrode current collector plate to the negative electrode current collector plate is 0.8 and 0.9. In the comparison of No. 13 to No. 17, when the positive electrode current collector plate is 0.8 mm, the comprehensive evaluation varies depending on the thickness of the negative electrode current collector plate, and the comprehensive evaluation is particularly high when the ratio of the thickness of the positive electrode current collector plate to the negative electrode current collector plate is 0.8 and 0.9.

[0045] In the comparison of No. 6, No. 11, No. 16, No. 18, and No. 19, when the ratio of the thickness of the positive electrode current collector plate to the negative electrode current collector plate is 0.8 and 0.9, and the thickness of the positive electrode current collector plate is 0.8 mm, 1.0 mm, and 1.2 mm, the comprehensive evaluation is higher than when the thickness of the positive electrode current collector plate is 0.7 mm and 1.3 mm. In the comparison of No. 16 and No. 20 to No. 23, when the thickness of the positive electrode current collector plate is 0.8 mm and the thickness of the negative electrode current collector plate is 1.0 mm, the comprehensive evaluation is particularly high by using dilute sulfuric acid containing aluminum ions at a concentration of 0.02 mol / L or more and 0.2 mol / L or less as the electrolytic solution.

[0046] It should be noted that in the liquid lead-acid batteries of No. 1 to No. 23 and No. 25 to No. 27 with an inter-electrode distance of 0.4 mm to 1.1 mm, no dendrite short circuit occurred after formation, whereas in the liquid lead-acid battery of No. 24 with an inter-electrode distance of 0.3 mm, a dendrite short circuit occurred after formation. In the comparison of No. 16 and No. 24 to No. 27, when the thickness of the positive electrode current collector plate is 0.8 mm and the thickness of the negative electrode current collector plate is 1.0 mm, by setting the inter-electrode distance to 0.4 mm or more and 1.0 mm or less, no dendrite short circuit occurs, sufficient discharge performance and formation efficiency are obtained, and the comprehensive evaluation is higher, as compared with the case where the inter-electrode distance is 0.3 mm or 1.1 mm.

[0047] 1. Battery case 4. Cell chamber 3. Electrode plate group 6. Laminate 71. Positive electrode strap 8. Positive electrode terminal pole 72. Negative electrode strap 9. Negative electrode terminal pole 10. Positive electrode plate (positive electrode filling plate) 101. Positive electrode current collector plate 101a. Grid-like portion of positive electrode current collector plate 101b. Ear portion of positive electrode current collector plate 102. Positive electrode mixture 111. Grid-like portion holding the positive electrode mixture 20. Negative electrode plate (negative electrode filling plate) 211. Grid-like portion holding the negative electrode mixture 201. Negative electrode current collector plate 201a. Grid-like portion of negative electrode current collector plate 201b. Ear portion of negative electrode current collector plate 201c. Feet portion of negative electrode current collector plate 202. Negative electrode mixture 30. Separator 31. Base 32. Rib 301. Bag-shaped separator W Distance between electrode plates

Claims

1. A liquid lead-acid battery comprising a group of electrode plates and an electrolyte, wherein the group of electrode plates is housed together with the electrolyte in a cell chamber, the group of electrode plates has a laminate comprising alternatingly arranged negative and positive electrode plates and a separator disposed between the negative and positive electrode plates, the positive electrode plate has a positive electrode current collector plate and a positive electrode mixture held on the positive electrode current collector plate, the negative electrode plate has a negative electrode current collector plate and a negative electrode mixture held on the negative electrode current collector plate, the thickness of the positive electrode current collector plate is less than the thickness of the negative electrode current collector plate, and the distance between adjacent positive and negative electrode plates is 0.4 mm or more and 1.0 mm or less.

2. The liquid lead-acid battery according to claim 1, wherein the electrolyte is dilute sulfuric acid containing aluminum ions at a concentration of 0.02 mol / L or more and 0.2 mol / L or less.

3. The liquid lead-acid battery according to claim 1, wherein the thickness of the positive electrode current collector plate is 0.8 mm or more and 1.2 mm or less.

4. The liquid lead-acid battery according to claim 1, wherein the ratio of the thickness of the positive electrode current collector plate to the thickness of the negative electrode current collector plate is 0.8 or more and less than 1.

0.

5. The liquid lead-acid battery according to claim 1, wherein the negative electrode current collector plate is a cast product having feet at the lower part of the grid-like portion, and the positive electrode current collector plate is a stamped product without the feet.

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