Diaper accumulator

Abstract

Lead-acid battery in which at least one electrode plate group, configured such that a plurality of positive electrode plates and a plurality of negative electrode plates are stacked on top of each other, wherein a separator is arranged between adjacent positive and negative electrode plates, is housed together with an electrolyte in at least one cell chamber, where each positive electrode plate includes a positive electrode grid made of lead or a lead alloy that does not contain antimony, a positive electrode surface layer formed on a surface of the positive electrode grid and consisting of an antimony-containing lead alloy, and a positive electrode active material with which the positive electrode grid is filled and which includes lead oxide, Each negative electrode plate contains a negative electrode grid made of lead or a lead alloy that does not contain antimony, a negative electrode surface layer formed on a surface of the negative electrode grid and consisting of an antimony-containing lead alloy, and a negative electrode active material with which the negative electrode grid is filled and which includes lead oxide, NS / PS falls into a range of 0.3 to 0.8, where PS represents an area of ​​the positive electrode surface layer on the surface of the positive electrode grid and NS represents an area of ​​the negative electrode surface layer on the surface of the negative electrode grid, and The positive and negative electrode surface layers consist of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%.

Description

Technical field

[0001] The present invention relates to lead-acid batteries used for idle-stop vehicles. Background of the technology

[0002] Fuel consumption in a vehicle that idles can be improved by switching off the engine while the vehicle is stationary. However, since a lead-acid battery powers everything from the air conditioning and blower during idling, it is likely to be in an undercharged state. To counteract this undercharge, a high charge input is required, allowing the battery to be charged more strongly over a short period. Furthermore, because a vehicle that idles frequently switches the engine on and off, a subsequent discharge occurs before lead dioxide and lead are recovered from lead sulfate produced during a previous discharge. This likely reduces the battery's lifespan.For such reasons, a long lifespan is also required for the lead-acid battery in order to counteract a decrease in service life.

[0003] To improve the charge acceptance of the lead-acid battery, patent document 1 describes a lead-acid battery containing an electrolyte with aluminum ions. The aluminum ions reduce the coarsening of the lead sulfate that forms at the positive and negative electrodes during discharge, thereby improving the charge acceptance of the lead-acid battery.

[0004] Patent document 1 also describes that an alloy layer based on lead-antimony, formed on a surface of a negative electrode grid, can reduce a decrease in the thickness of an ear part of the negative electrode in an idle stop mode.

[0005] To improve the lifespan of the lead-acid battery, patent document 2 describes a lead-acid battery in which an antimony-containing lead alloy layer is formed on a surface of a negative electrode grid that does not contain antimony. The antimony-containing lead alloy layer has the effect of efficiently recovering charge from a negative electrode plate, thereby improving the lifespan of the lead-acid battery.

[0006] Patent document 3 describes a lead-acid battery in which a negative electrode grid, which does not contain antimony, is filled with an antimony-containing negative electrode active material, and the mass ratio of the negative electrode active material to a positive electrode active material falls within the range of 0.7 to 1.3. The antimony added to the negative electrode active material reduces the hydrogen overpotential of the negative electrode, thereby improving the charge acceptance of the negative electrode active material. Furthermore, since the mass ratio of the negative electrode active material to the positive electrode active material falls within the range of 0.7 to 1.3, elution of antimony from the negative electrode active material into the electrolyte during deep discharge of the lead-acid battery and deposition of antimony on a portion of the negative electrode are reduced.This can reduce corrosion of the ear part of the negative electrode.

[0007] Patent document 4 discloses that, in order to counteract a short lifetime caused by an increase in the frequency of discharge due to the operating conditions, where the frequency of temporary stopping accompanied by an idle stop is high, the density of a positive electrode active material is 3.5 to 4.5 g / cc, the specific gravity of an electrolyte is 1.240 to 1.260 (20 °C), and the amount of carbon, which is an additive to a negative electrode plate, is 0.5 to 2.0% per mass of a negative electrode active material.

[0008] Patent document 5 describes a lead-acid battery of the control valve type in which the mass ratio of sulfuric acid in an electrolyte to a positive electrode active material falls within a predetermined range and sodium tetraborate is added to the electrolyte. This reduces the deposition of lead dendrites during recharging after a deep discharge, thereby reducing or preventing an internal short circuit.

[0009] Patent document 6 describes a technique for reducing lead ion generation and decreasing sulfuric acid concentration during deep discharge by adding alkali metal sulfate, such as Na₂SO₄, to an electrolyte. It also describes a technique for reducing or preventing short circuits between positive and negative electrodes by allowing PbSO₄ to grow on the negative electrode during charging. The added Na₂SO₄ reduces the electrolyte's conductivity due to a decrease in sulfuric acid concentration during deep discharge and improves charge recovery after deep discharge. Patent document 7 describes a negative electrode for a lead-acid battery that has an antimony-containing alloy layer.Patent document 8 discloses a positive electrode for a lead-acid battery, consisting of an antimony-free lattice framework with a coating of an antimony-containing lead alloy. Examples of commercially available lead-acid batteries and electrode materials are disclosed in patent documents 9 to 13. List of citations patent document Patent document 1: JP 2006 - 004 636 A Patent document 2: JP 2006 - 156 371 A Patent document 3: JP 2006 - 114 417 A Patent document 4: JP 2003 - 151 617 A Patent document 5: JP 2007 - 035 339 A Patent document 6: JP H01 - 267 965 A Patent document 7: WO 2012 / 153 464 A1 Patent document 8: DE 698 34 081 T2 Patent document 9: US 2007 / 0 184 349 A1 Patent document 10: US 6 291 104 B1 Patent document 11: US 2010 / 0 203 362 A1 Patent document 12: US 4,725,516 A Patent document 13: US 2007 / 0 160 910 A1 Overview of the invention Technical problem

[0010] Lead-acid batteries used in idle-stop vehicles are likely to be in an insufficiently charged state. To reduce or prevent deep discharge of the lead-acid batteries, fail-safe mechanisms can therefore be provided in the idle-stop vehicles. These mechanisms are designed to prevent the lead-acid batteries from discharging when the state of charge (SOC) falls below or is equal to a predetermined value (e.g., 60%).

[0011] Fig. Figure 1 shows graphs that schematically represent a state of charge (SOC) when a lead-acid battery is repeatedly discharged and charged in an idle-stop vehicle. The graphs in Figure 1 illustrate this process. Fig.The line graph shown in Figure 1 illustrates the pattern in which the process of decreasing the SOC by discharging the lead-acid battery while the vehicle is stopped, and the process of charging the lead-acid battery to restore the SOC, are repeated after the vehicle has been restarted.

[0012] With a high charge acceptance of the lead-acid battery, the state of charge (SOC) of the lead-acid battery is restored to approximately 100% while the vehicle is driving. As shown in line graph A of Fig. As shown in Figure 1, the charging / discharging of the lead-acid battery can therefore be repeated even if the idle stop vehicle drives for a long period of time.

[0013] Without a high charge acceptance of the lead-acid battery, charging can occur, as shown in line graph B of Fig.Figure 1 illustrates this process, but it cannot be performed adequately while the vehicle is in motion. If the vehicle stops in a state where the SOC has not been fully restored, the SOC will decrease significantly due to discharge. If such a charge / discharge cycle is repeated, the SOC will continue to decrease gradually. If a failsafe mechanism is provided in the idling stop vehicle, this mechanism will be activated to stop a discharge if the SOC becomes equal to or less than a predetermined value (e.g., 60%).

[0014] In particular, when each trip is short (hereinafter referred to as "short-distance driving"), sufficient charging may not occur while the vehicle is in motion, and the state of charge (SOC) will not be fully restored. This leads to frequent activation of the failsafe mechanism. Furthermore, if the vehicle is only used for short-distance driving on weekends, the SOC decreases further due to self-discharge and dark current draw during periods of inactivity, thus triggering the failsafe mechanism even more frequently. Historically, however, no lead-acid batteries suitable for idling-stop vehicles operating in the short-distance driving mode described above have offered both sufficient charge capacity and adequate durability (lifespan rating).

[0015] It is assumed that the lead-acid battery, having been temporarily discharged into a deep discharge state, is reused in short-distance driving mode, resulting in repeated charging / discharging cycles. With poor charge recovery, the charging / discharging balance cannot be achieved, and therefore the condition in which the failsafe mechanism is activated frequently recurs. In the worst case, the idle stop is permanently disabled. Furthermore, since the lead-acid battery is used with a low state of charge (SOC), there is a possibility that its lifespan will be shortened due to sulfation.In the past, however, there were no lead-acid batteries available that were suitable for idle-stop vehicles used in the above short-distance driving mode and that offered sufficient charge acceptance, sufficient durability (lifetime rating), and sufficient charge recovery after deep discharge.

[0016] The present invention has been made in light of the above and is mainly intended to provide a lead-acid battery suitable for use in an idle-stop vehicle operating in a short-distance driving mode, and which has both sufficient charge capacity, sufficient durability (lifespan rating) and sufficient charge recovery after deep discharge. Solution to the problem

[0017] A lead-acid battery of the present invention is intended for a lead-acid battery in which at least one electrode plate group, configured such that a plurality of positive electrode plates and a plurality of negative electrode plates are stacked one on top of the other, wherein a separator is arranged between adjacent positive and negative electrode plates, is housed together with an electrolyte in at least one cell chamber, wherein each positive electrode plate comprises: a positive electrode grid made of lead or a lead alloy that does not contain antimony; a positive electrode surface layer formed on a surface of the positive electrode grid and made of an antimony-containing lead alloy; and a positive electrode active material with which the positive electrode grid is filled and which comprises lead oxide;Each negative electrode plate comprises: a negative electrode grid made of lead or a lead alloy that does not contain antimony; a negative electrode surface layer formed on a surface of the negative electrode grid and made of an antimony-containing lead alloy; and a negative electrode active material with which the negative electrode grid is filled and which comprises lead oxide; NS / PS falls within a range of 0.3 to 0.8, where PS represents an area of ​​the positive electrode surface layer on the surface of the positive electrode grid and NS represents an area of ​​the negative electrode surface layer on the surface of the negative electrode grid; and the positive and negative electrode surface layers are made of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%. Advantages of the invention

[0018] According to the present invention, a lead-acid battery can be provided which is suitable for an idle-stop vehicle used in a short-distance driving mode and which has both sufficient charge absorption, sufficient durability (lifetime characteristic) and sufficient charge recovery after deep discharge. Brief description of the drawings [ Fig. 1] Fig. Figure 1 shows graphs that schematically represent a SOC when a discharge and charge of a lead-acid battery is repeatedly performed in an idle-stop vehicle. [ Fig. 2] Fig. Figure 2 is a schematic representation illustrating the outline of a lead-acid battery of an embodiment of the present invention. [ Fig. 3] Fig. Figure 3 is a cross-sectional view illustrating a design of an electrode plate group housed in a cell chamber. [ Fig. 4] Fig. Figure 4 is a cross-sectional view of a strand of a grid. Description of embodiments

[0019] Embodiments of the present invention are described in detail below with reference to the drawings. (First comparative version)

[0020] Fig. Figure 2 is a schematic representation illustrating the outline design of a lead-acid battery 1 of a first comparative design form.

[0021] With reference to Fig. 2 is in the lead-acid battery 1 an electrode plate group 5 in which a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3 are stacked on top of each other, wherein a separator 4 is arranged between adjacent of the positive and negative electrode plates 2, 3, together with an electrolyte in each cell chamber 6.

[0022] The positive electrode plate 2 comprises a positive electrode grid and a positive electrode active material with which the positive electrode grid is filled, and the negative electrode plate 3 comprises a negative electrode grid and a negative electrode active material with which the negative electrode grid is filled. It should be noted that the positive and negative electrode grids of the present embodiment are made of lead or of a lead alloy that does not contain antimony (Sb), such as a Pb-Ca alloy, a Pb-Sn alloy, or a Pb-Sn-Ca alloy.

[0023] The positive electrode plates 2 are connected in parallel to each other at ear sections 9 of the positive electrode grids by a positive electrode holder 7, and the negative electrode plates 3 are connected in parallel to each other at ear sections 10 of the negative electrode grids by a negative electrode holder 8. The electrode plate groups 5, each housed in the cell chambers 6, are connected in series by a connector 11. The positive electrode holder 7 and the negative electrode holder 8, each housed in the cell chambers 6 located at both ends of the lead-acid battery 1, are each welded to (not shown) poles, and each pole is welded to a corresponding positive and negative electrode terminal 12, 13 arranged on a cover 14.

[0024] In the present comparative embodiment, a surface layer (not shown) consisting of an antimony-containing lead alloy is formed on a surface of the negative electrode grid. The antimony-containing lead alloy reduces hydrogen overpotential, thereby improving the charge acceptance of the lead-acid battery 1. It should be noted that the surface layer preferably consists of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%.

[0025] Furthermore, in the present comparative design, a mass ratio M N / M P specified in a range of 0.70 to 1.10 and preferably a range of 0.80 to 1.00, wherein “M P “ represents the mass of the positive electrode active material per cell chamber 6 and “M N“represents the mass of the negative electrode active material per cell chamber 6. If the mass ratio M N / M P If the difference in active material between the negative electrode and positive electrodes falls within the range described above, a service life can be maintained, and the charge acceptance of the lead-acid battery 1 can be improved. Even if the lead-acid battery 1 is used in an idle-stop vehicle operating in short-distance driving mode, this can reduce the activation of a failsafe mechanism.

[0026] In the present comparative embodiment, the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. The sodium ions contained in the electrolyte have the effect of improving charge recovery after deep discharge, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0027] In the present comparative embodiment, the W / L ratio preferably falls within a range of 0.50 to 0.80, where "L" represents the internal dimension of the cell chamber 6 in the stacking direction of the electrode plate groups 5, and "W" represents the total thickness of the positive and negative electrode plates 2, 3. The W / L value represents the size of the gap between the positive electrode plate 2 and the negative electrode plate 3, i.e., the measure of the amount of electrolyte entering such a gap. When the W / L value falls within a range of 0.50 to 0.80, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0028] Preferably, in the present comparative embodiment, the negative electrode plates 3 are arranged on both sides of the electrode plate group 5 and are each housed in a corresponding pocket-shaped separator 4. A plurality of ribs are formed on an inner part of each separator 4 to create a certain gap between the negative electrode plate 3 and the separator 4. This allows the electrolyte to enter such a gap in each of the negative electrode plates 3, which are arranged on both sides of the electrode plate group 5, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle-stop vehicle, which is used in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0029] The above advantages can be achieved if the ribs are formed at least on the separators 4, each housing one of the corresponding negative electrode plates 3, which are arranged on both sides of the electrode plate group 5. Of course, however, a plurality of ribs can be formed on the separators 4, each housing one of all the corresponding negative electrode plates 3. If the lead-acid battery 1 contains only a single cell chamber 6, a container of the lead-acid battery 1 can also serve as the cell chamber 6. First reference example(1) Training of a lead-acid battery

[0030] The lead-acid batteries 1 formed in the present reference examples are liquid lead-acid batteries with a size of D23L, as specified in JIS D 5301. Seven positive electrode plates 2 and eight negative electrode plates 3 are housed in each cell chamber 6, and each negative electrode plate 3 is housed in a pocket-shaped separator 4 made of polyethylene.

[0031] Each positive electrode plate 2 was formed in such a way that lead oxide powder is mixed with sulfuric acid and demineralized water to form a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0032] Each negative electrode plate 3 was formed in such a way that an organic additive, etc., is added to the lead oxide powder, the result is mixed with sulfuric acid and demineralized water to produce a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0033] After the formed positive electrode plates 2 and the formed negative electrode plates 3 had matured and dried, the negative electrode plates 3 were each placed in pocket-shaped separators 4 made of polyethylene, and then the negative electrode plates 3 and the positive electrode plates 2 were stacked alternately on top of each other. As a result, an electrode plate group 5 was formed in which the seven positive electrode plates 2 and the eight negative electrode plates 3 are stacked on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2 and 3. The electrode plate group 5 was placed in each of the six cell chambers 6, and a lead-acid battery 1 was formed in which six cells are connected in series.

[0034] An electrolyte consisting of dilute sulfuric acid with a density of 1.28 g / cm³3 The substance was introduced into the lead-acid battery 1, and subsequently a chemical transformation was carried out in a container. As a result, a lead-acid battery 1 with 12 V and 48 Ah was formed. (2) Evaluation of lead-acid battery characteristics (2-1) Evaluation of the lifetime characteristic

[0035] The trained lead-acid battery underwent repeated charging / discharging cycles designed for an idle stop in order to evaluate the battery's lifespan characteristic.

[0036] A lifetime rating test was performed under the following conditions, essentially in accordance with the Storage Battery Association standard (SBA S 0101). It should be noted that the ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 59 seconds at a discharge current of 45 A is performed, a discharge over 1 second at 300 A is performed. (B) Subsequently, charging is carried out for 60 seconds with a charging voltage of 14.2 V (a limited current of 100 A). (C) Every 3,600 cycles, the lead-acid battery is left unattended for 48 hours, with the discharge (A) and charging (B) counted as one cycle, and then the cycles are resumed.

[0037] The above cycles were repeated, and the number of cycles in which the discharge voltage fell below 7.2 V was considered the lifetime indicator. It should be noted that in the above test, water was not added until after 30,000 cycles. (2-2) Evaluation of the characteristic value in short-distance driving mode

[0038] The trained lead-acid battery 1 underwent repeated charging / discharging cycles designed for short-distance driving mode to evaluate its performance characteristics in this mode. The ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 2.5 hours at a discharge current of 9.6 A, the lead-acid battery is left unattended for 24 hours. (B) A discharge is carried out over 40 seconds at a discharge current of 20 A. (C) Charging is carried out over 60 seconds with a charging voltage of 14.2 V (a limited current of 50 A). (D) After the discharge (B) and charge (C) have been repeated 18 times, a discharge is carried out for 83.5 hours at a discharge current of 20 mA. (E) The cycles are repeated 20 times, with the discharge (B), the charging (C) and the discharge (D) being counted as a single cycle.

[0039] The state of charge (SOC) of the lead-acid battery after 20 cycles was measured, and such a value was considered as a characteristic value in the short-distance driving mode. (Reference example 1-1)

[0040] Accumulators A1 to A7 were formed, in each of which a surface layer consisting of an antimony-containing lead alloy is formed on a surface of a negative electrode grid and a mass ratio M N / M P falls within a range of 0.65 to 1.15, where "M P “ represents the mass of a positive electrode active material per cell chamber and “M”, represents the mass of a negative electrode active material per cell chamber. The lifetime rating of each battery and the rating of each battery in the short-distance driving mode were evaluated.

[0041] The negative electrode grid is formed from an expanded metal lattice of Pb-1.2Sn-0.1Ca, and the surface layer is made from a Pb-3Ma%Sb foil. In addition, a positive electrode grid is formed from an expanded metal lattice of Pb-1.6Sn-0.1Ca, and no surface layer is formed on the positive electrode grid.

[0042] Table 1 presents the evaluation results for each characteristic value. It should be noted that an accumulator A8, in which no surface layer is formed on the surface of a negative electrode grid, was used as a comparison example. Furthermore, since it is difficult to form an expanded metal grid as a negative electrode grid from a lead alloy containing Sb, such an expanded metal grid was not considered. [Table 1] Mass ratio M N / M P Negative electrode plate Lifetime characteristic (frequency) Key performance indicator in short-distance driving mode SOC (%) Negative electrode grid surface layer Accumulator A1 0,65 Pb-Sn-Ca Pb-Sb 28.800 54 Accumulator A2 0,70 Pb-Sn-Ca Pb-Sb 32.400 71 Accumulator A3 0,80 Pb-Sn-Ca Pb-Sb 39.600 74 Accumulator A4 0,90 Pb-Sn-Ca Pb-Sb 43.200 75 Accumulator A5 1,00 Pb-Sn-Ca Pb-Sb 39.600 74 Accumulator A6 1,10 Pb-Sn-Ca Pb-Sb 28.800 73 Accumulator A7 1,15 Pb-Sn-Ca Pb-Sb 18.000 72 Accumulator A8 0,80 Pb-Sn-Ca untrained 28.800 45

[0043] As can be seen from Table 1, the accumulators A2 to A6, whose mass ratio M N / M P If the value falls within the range of 0.70 to 1.10, the lifetime rating is equal to or greater than 28,800, and the SOC, which indicates the rating in short-distance driving mode, is equal to or greater than 71%. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idle-stop vehicle is used in short-distance driving mode. Specifically, batteries A3 to A5, whose mass ratio M N / M PIf the rating falls within the range of 0.80 to 1.00, these batteries exhibit excellent characteristics, as the lifetime rating is equal to or greater than 39,600 and the state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 74%. These batteries demonstrate superior performance when the vehicle is used in short-distance driving mode.

[0044] In contrast, the accumulator A1, whose mass ratio M N / M P The value is 0.65, indicating a lifetime rating of 28,800, but it shows that the SOC, which represents the rating in short-distance driving mode, has a low value of 54%. This may be due to an insufficient amount of negative electrode active material compared to the amount of positive electrode active material, resulting in reduced charge uptake.

[0045] Furthermore, the accumulator A7, whose mass ratio M N / M PThe value of 1.15 indicates that the SOC, which represents the characteristic value in short-distance driving mode, is 72%, but it shows that the lifetime characteristic has a low value of 18,000. This can be due to the following reasons: Since the amount of positive electrode active material is insufficient compared to the amount of negative electrode active material, the positive electrode active material softens. Repeated charging / discharging weakens the bond between the positive electrode active materials, and therefore the positive electrode plate deteriorates.

[0046] The A8 battery, in which no surface layer is formed on the negative electrode grid, shows a lifetime rating of 28,800 hours. However, it exhibits an extremely low state of charge (SOC) of 45%, which indicates the rating in short-distance driving mode. This can be attributed to the following: Because the lead-containing foil is not formed on the surface of the negative electrode grid, the hydrogen overpotential does not decrease, and therefore the charge acceptance is low.

[0047] Based on the above results, a lead-acid battery that reduces the activation of a failsafe mechanism and is adaptable for an idle-stop vehicle used in a short-distance driving mode can be achieved by forming a surface layer consisting of an antimony-containing lead alloy on the surface of a negative electrode grid that does not contain antimony, and by ensuring that the mass ratio M N / M P a negative electrode active material to a positive electrode active material is defined in a range of 0.70 to 1.10 and preferably in a range of 0.80 to 1.00. (Reference example 1-2)

[0048] To further improve charge acceptance, batteries A9 to A15 were subsequently formed from battery A4 as described in Reference Example 1-1, such that the sodium ion concentration in the electrolyte fluctuated between 0.005 and 0.56 mol / L. The lifetime rating of each battery and its short-range driving performance were evaluated. Battery A12 is identical to battery A4 as described in Reference Example 1-1.

[0049] The concentration of Na ions in the electrolyte was adjusted so that the amount of sodium sulfate to be added to the electrolyte changed.

[0050] It should be noted that in the present reference example, the charge recovery in a deep discharge state of the lead-acid battery was additionally evaluated by the following test procedure when assessing the characteristic value in the short-distance driving mode.

[0051] This assessment was conducted based on the following assumption: If the lead-acid battery, which has been revived after entering a deep discharge state, is reused in short-distance driving mode in such a way that a charge / discharge cycle is repeated, and the battery's charge recovery is poor, its already low state of charge (SOC) will decrease further through discharge, and therefore the failsafe mechanism will be activated more frequently. <Ladungsrückgewinnung nach Tiefentladung> (A) A discharge is carried out at a current with a five-hour rate (a discharge current of 9.8 A) down to 10.5 V. (B) Subsequently, a discharge is carried out under a load of 10 W for 14 days at a temperature of 40 °C ± 2°C, and then the lead-acid battery is left unattended with the circuit interrupted for 14 days. (C) Subsequently, charging is carried out for four hours at a temperature of 25 °C ± 3 °C with a charging voltage of 15.0 V (a limited current of 25 A). (D) The lead-acid battery is then left unattended for 16 hours or longer in an atmosphere of -15 °C ± 1 °C, and then discharged with a discharge current of 300 A to 6.0 V.

[0052] The time it takes for the lead-acid battery voltage to reach 6.0 V was evaluated as the state of charge (SOC) recovery after a deep discharge.

[0053] Table 2 presents the results of the above evaluation. [Table 2] Mass ratio M N / M P Negative electrode plate Na ion content (mol / L) Lifetime characteristic (frequency) Key figure in short-distance driving mode SOC (%) Recovery after deep discharge Duration (minutes) Negative electrode grid surface layer Accumulator A9 0,90 Pb-Sn-Ca Pb-Sb 0,005 28.800 73 1,5 Accumulator A10 0,90 Pb-Sn-Ca Pb-Sb 0,01 32.400 73 2,5 Accumulator A11 0,90 Pb-Sn-Ca Pb-Sb 0,03 39.600 74 2,9 Accumulator A12 0,90 Pb-Sn-Ca Pb-Sb 0,11 43.200 75 3 Accumulator A13 0,90 Pb-Sn-Ca Pb-Sb 0,28 39.600 74 3 Accumulator A14 0,90 Pb-Sn-Ca Pb-Sb 0,45 32.400 70 3 Accumulator A15 0,90 Pb-Sn-Ca Pb-Sb 0,56 28.800 66 2,9

[0054] As can be seen from Table 2, batteries A10 to A14, whose sodium ion content in the electrolyte ranges from 0.01 to 0.45 mol / L, exhibit a lifetime rating of 32,400 or greater, a state of charge (SOC) that indicates the rating in short-distance driving mode of 70% or greater, and a recovery time after deep discharge of 2.5 minutes or more. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling-stop vehicle is used in short-distance driving mode. In particular, the accumulators A11 to A13, whose Na ion content in the electrolyte falls within a range of 0.03 to 0.28 mol / L, exhibit excellent properties, as the lifetime rating is equal to or greater than 39.600, the SOC (State of Charge), which indicates the characteristic value in short-distance driving mode, is equal to or higher than 74%, and the recovery time after a deep discharge is 2.9 minutes or longer. These batteries exhibit preferred performance when the idling vehicle is used in short-distance driving mode.

[0055] In contrast, the A9 battery, whose sodium ion concentration in the electrolyte is 0.005 mol / L, shows a low recovery time of 1.5 minutes after deep discharge. This may be due to reduced conductivity during deep discharge caused by a low number of sodium ions.

[0056] The A15 battery, with a sodium ion concentration of 0.56 mol / L in the electrolyte, shows a low state of charge (SOC) of 66%, which indicates the characteristic value in short-distance driving mode. This may be due to reduced charge acceptance resulting from a high number of sodium ions.

[0057] Based on the above results, recovery after a deep discharge can be improved by ensuring the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. Even when the lead-acid battery is used in an idle-stop vehicle operating in short-distance driving mode, this can more effectively reduce activation of the failsafe mechanism. (Reference example 1-3)

[0058] To further improve charge acceptance, accumulators A16 to A22 were subsequently configured from accumulator A4 as configured in Reference Example 1-1 such that the W / L ratio varies between 0.45 and 0.85, where "L" represents the internal dimension of the cell chamber in the stacking direction of the electrode plate groups and "W" represents the total thickness of the positive and negative electrode plates. The lifetime rating of each accumulator and its short-range driving performance were evaluated. Accumulator A19 is identical to accumulator A4 as configured in Reference Example 1-1.

[0059] Fig.Figure 3 is a cross-sectional view of cell chamber 6. The internal dimension of cell chamber 6 in the stacking direction of the electrode plate groups housed therein is represented by “L”, the thickness of the positive electrode plate 2 is represented by “W1”, the thickness of the negative electrode plate 3 is represented by “W2”, and the total thickness (W1 × 7 + W2 × 8) of the positive electrode plates 2 and the negative electrode plates 3 is represented by “W”.

[0060] Table 3 presents the evaluation results for each indicator. [Table 3] Mass ratio M N / M P Negative electrode plate Thickness ratio of electrode plates to cell chamber W / L Lifetime characteristic (frequency) Key figure in short-distance driving mode SOC (%) Negative electrode grid surface layer Accumulator A16 0,90 Pb-Sn-Ca Pb-Sb 0,45 28.800 64 Accumulator A17 0,90 Pb-Sn-Ca Pb-Sb 0,50 39.600 71 Accumulator A18 0,90 Pb-Sn-Ca Pb-Sb 0,60 39.600 74 Accumulator A19 0,90 Pb-Sn-Ca Pb-Sb 0,65 43.200 75 Accumulator A20 0,90 Pb-Sn-Ca Pb-Sb 0,70 39.600 74 Accumulator A21 0,90 Pb-Sn-Ca Pb-Sb 0,80 39.600 71 Accumulator A22 0,90 Pb-Sn-Ca Pb-Sb 0,85 39.600 66

[0061] As can be seen from Table 3, batteries A17 to A21, whose W / L ratio falls within the range of 0.50 to 0.80, exhibit a lifetime rating of 39,600 or greater and a state of charge (SOC), which indicates the rating in short-distance driving mode, of 71% or greater. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in short-distance driving mode. In particular, batteries A18 to A20, whose W / L ratio falls within the range of 0.60 to 0.70, show excellent characteristics, as their lifetime rating is 39,600 or greater and their state of charge (SOC), which indicates the rating in short-distance driving mode, is 74% or greater.These batteries exhibit preferred performance when the idling stop vehicle is used in short-distance driving mode.

[0062] In contrast, the A16 battery, with a W / L ratio of 0.45, shows a lifetime rating of 28,800 hours, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 64%. This may be due to reduced charge acceptance resulting from a lack of active material.

[0063] The A22 battery, with a W / L ratio of 0.85, shows a lifetime rating of 39,600, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 66%. This may be due to reduced charge acceptance caused by a lack of electrolyte entering the spaces between adjacent cells in the A22 battery.

[0064] Based on the above results, the charge acceptance can be further improved so that the W / L ratio is set in the range of 0.50 to 0.80, and preferably in the range of 0.60 to 0.70. Even when the lead-acid battery is used for the idle-stop vehicle operating in a short-distance driving mode, this can more effectively reduce the activation of the failsafe mechanism. (Reference example 1-4)

[0065] To further improve charge absorption, an accumulator A23 was next formed from the accumulator A3 formed in reference example 1-1 such that a plurality of ribs 15 are formed on the inner part of the separator 4 to form a certain space between the negative electrode plate 3 and the pocket-shaped separator 4 in which the negative electrode plate 3 is housed.It should be noted that an accumulator A24, in which ribs 15 are configured to face the positive electrode plates 2, an accumulator A25, in which each positive electrode plate 2 is housed in a corresponding pocket-shaped separator 4 and ribs 15 are configured to face the negative electrode plates 3, and an accumulator A26, in which plate-shaped separators are used instead of pocket-shaped separators 4 and ribs 15 are configured to face the negative electrode plates 3, were designed as comparative examples. The height of the rib 15 was 0.2 mm, and it was formed integrally with the separator 4.

[0066] Table 4 presents the evaluation results for each indicator. [Table 4] M N / M P Negative electrode plate separator Lifetime characteristic (frequency) Key figure in short-distance driving mode SOC (%) Negative electrode grid surface layer form Element to be accommodated rib Accumulator A23 0,90 Pb-Sn-Ca Pb-Sb Bag Negative electrode plate negative electrode side 39.600 75 Accumulator A24 0,90 Pb-Sn-Ca Pb-Sb Bag Negative electrode plate Positive electrode side 39.600 66 Accumulator A25 0,90 Pb-Sn-Ca Pb-Sb Bag Positive electrode plate negative electrode side 39.600 67 Accumulator A26 0,90 Pb-Sn-Ca Pb-Sb plate - negative electrode side 39.600 64

[0067] As can be seen from Table 4, the A23 battery, in which the ribs on the inner part of the separator are designed to face the negative electrode plates, exhibits a lifetime rating of 39,600 and a state of charge (SOC) of 75%, which indicates the rating in short-distance driving mode. With a lead-acid battery exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idle-stop vehicle is used in short-distance driving mode.

[0068] In contrast, of the battery A24, in which the ribs are configured to face the positive electrode plates, the battery A25, in which each positive electrode plate is housed in a corresponding pocket-shaped separator and the ribs are configured to face the negative electrode plates, and the battery A26, in which the plate-shaped separator is used and the ribs are configured to face the negative electrode plates, each shows that the SOC, which indicates the characteristic value in the short-distance driving mode, has a low value of 67% or less. This can have the following causes.When the negative electrode plates, each arranged on both sides in the electrode plate group, are pressed against the inner walls of the cell chamber, no space is formed between the negative electrode plate and the cell chamber, and the charge uptake is reduced due to a lack of electrolyte entering the space between adjacent elements in the accumulator.

[0069] Based on the above results, the charge acceptance of the lead-acid battery can be further improved by accommodating each negative electrode plate within the pocket-shaped separator and by forming ribs on the inner part of the separator to create a gap between the negative electrode plate and the separator. Even when the lead-acid battery is used in an idle-stop vehicle operating in short-distance driving mode, this can more effectively reduce the activation of the failsafe mechanism. (First embodiment)

[0070] Fig. Figure 2 is a schematic representation which also illustrates an outline design of a lead-acid battery 1 of a first embodiment of the present invention.

[0071] With reference to Fig.2 is in the lead-acid battery 1 an electrode plate group 5 in which a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3 are stacked on top of each other, wherein a separator 4 is arranged between adjacent of the positive and negative electrode plates 2, 3, together with an electrolyte in each cell chamber 6.

[0072] The positive electrode plate 2 comprises a positive electrode grid and a positive electrode active material with which the positive electrode grid is filled, and the negative electrode plate 3 comprises a negative electrode grid and a negative electrode active material with which the negative electrode grid is filled. It should be noted that the positive and negative electrode grids of the present embodiment are made of lead or of a lead alloy that does not contain antimony (Sb), such as a Pb-Ca alloy, a Pb-Sn alloy, or a Pb-Sn-Ca alloy. The expression "does not contain antimony" means that no antimony is added as an alloying element, and the case in which a raw material contains a small amount of antimony as an impurity is considered antimony-free.This means that, in cases where antimony is an unavoidable impurity, the present invention contains no antimony. Antimony-containing surface layers (not shown) are formed on the surfaces of the positive and negative electrode grids. It should be noted that the surface layer consists of a Pb-Sb alloy containing antimony at a concentration of 1.0 to 5.0 wt%.

[0073] The positive electrode plates 2 are connected in parallel to each other at ear sections 9 of the positive electrode grids by a positive electrode holder 7, and the negative electrode plates 3 are connected in parallel to each other at ear sections 10 of the negative electrode grids by a negative electrode holder 8. The electrode plate groups 5, each housed in the cell chambers 6, are connected in series by a connector 11. The positive electrode holder 7 and the negative electrode holder 8, each housed in the cell chambers 6 located at both ends of the lead-acid battery 1, are each welded to (not shown) poles, and each pole is welded to a corresponding positive and negative electrode terminal 12, 13 arranged on a cover 14.

[0074] The positive and negative electrode surface layers, formed on the surfaces of the positive and negative electrode grids and containing antimony, are formed from a Pb-Sb-based alloy foil bonded to the surfaces of lead alloy plates to create the grids. The grid structure is identical to that of expanded metal. Consequently, when the cross-section of a strand 31 of the grid is examined using electron beam microanalysis, the following is determined with reference to Fig. 4. An Sb-containing part 32 was found on one side of the rectangular cross-section.

[0075] In the present embodiment, the area PS of the positive electrode surface layer is larger than the area NS of the negative electrode surface layer, and NS / PS falls within a range of 0.3 to 0.8. That is, a value PS obtained by summing the area of ​​a positive electrode surface layer on strands and the area of ​​a positive electrode surface layer on connections in a single positive electrode grid is larger than a value NS obtained by summing the area of ​​a negative electrode surface layer on strands and the area of ​​a negative electrode surface layer on connections in a single negative electrode grid. The values ​​PS and NS each correspond substantially to the area of ​​a Pb-Sb-containing alloy foil bonded to the surface of the lead alloy plate to form the grid.

[0076] As described in patent documents 1 and 2, the advantages of forming the antimony-containing layer on the surface of the negative electrode grid are a reduction in the thickness of the negative electrode's ear portion during idle stop-start operation and efficient charge recovery from the negative electrode plate. However, the disadvantage of forming the antimony-containing layer on the surface of the negative electrode grid is an acceleration of water electrolysis. For these reasons, the negative electrode surface layer is preferably not designed to have a larger area than necessary.

[0077] Furthermore, an investigation was carried out by the inventors of the present invention, and it was found that lead (Pb), which is a negative electrode active material, and lead sulfate, which is a discharge product, accumulate on a negative electrode surface layer due to repeated charging / discharging cycles, and that the accumulated Pb and lead sulfate cover the surface layer to such an extent that the charge recovery function of a negative electrode plate is reduced. This is a major disadvantage for idling stop vehicles used in short-distance driving mode.As a result of various types of investigations, it has been found that a sulfur-containing surface layer is formed on the surface of a positive electrode grid in such a way that it has a larger area than that of the negative electrode surface layer. This overcomes the aforementioned disadvantage for use in idle-stop vehicles without reducing various performance characteristics in short-distance driving mode. Furthermore, it has also been found that the performance characteristic in short-distance driving mode is further improved when the NS / PS ratio is equal to or greater than 0.3 and equal to or less than 0.8.

[0078] This means that the Sb-containing surface layer formed on the surface of the positive electrode grid can reduce or prevent a decrease in the charge recovery function of the negative electrode plate caused by the gradual elution of Sb from the positive electrode surface layer during repeated charging / discharging cycles and the migration of Sb to the negative electrode plate. Even in applications such as idling stop vehicles used in short-distance driving mode, the activation of a failsafe mechanism can be reduced.

[0079] With repeated charging / discharging cycles, the surface area of ​​the negative electrode surface layer decreases, and consequently, the effectiveness of the Sb contained in the negative electrode surface layer is reduced. For these reasons, the negative electrode surface layer is preferably designed to have a higher antimony content than the positive electrode surface layer. This can improve the charge acceptance of the lead-acid battery 1 over a long period. Even when the lead-acid battery 1 is used for the idle stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can be further reduced.

[0080] A high-performance rotary process is preferred for manufacturing positive and negative electrode grids; however, one or more strands can become twisted during such a manufacturing process. Since corrosion begins on such a twisted part(s) of the positive electrode and shortens the battery life, the positive electrode grids are preferably manufactured using a reciprocating process that does not cause twisting.

[0081] In a preferred example of the present embodiment, an electrolyte contains aluminum ions. As described in patent document 1, the electrolyte containing aluminum ions can improve the charge acceptance of the lead-acid battery. Even when such a battery is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can be further reduced.

[0082] Furthermore, in the present embodiment the mass ratio M N / M P specified in a range of 0.70 to 1.10 and preferably a range of 0.80 to 1.00, wherein “M P “ represents the mass of the positive electrode active material per cell chamber 6 and “M N “represents the mass of the negative electrode active material per cell chamber 6. If the mass ratio M N / M P If the temperature difference between the negative electrode active material and the positive electrode active material falls within the range mentioned above, a service life value can be maintained, and the charge acceptance of the lead-acid battery 1 can be improved. Even if the lead-acid battery 1 is used for the idle stop vehicle, which is used in short-distance driving mode, activation of the fail-safe mechanism can thus be reduced.

[0083] In the present embodiment, the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. The sodium ions contained in the electrolyte have the effect of improving charge recovery after deep discharge, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0084] In the present embodiment, the W / L ratio preferably falls within a range of 0.50 to 0.80, where "L" represents the internal dimension of the cell chamber 6 in the stacking direction of the electrode plate groups 5, and "W" represents the total thickness of the positive and negative electrode plates 2, 3. The W / L value represents the size of the gap between the positive electrode plate 2 and the negative electrode plate 3, i.e., the measure of the amount of electrolyte entering such a gap. When the W / L value falls within a range of 0.50 to 0.80, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0085] Preferably, in the present embodiment, the negative electrode plates 3 are arranged on both sides of the electrode plate group 5 and are each housed in a corresponding pocket-shaped separator 4. A plurality of ribs are formed on an inner part of the separator 4 to create a certain gap between the negative electrode plate 3 and the separator 4. This allows the electrolyte to enter such a gap in each of the negative electrode plates 3, which are arranged on both sides of the electrode plate group 5, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle-stop vehicle, which is used in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0086] The above advantages can be achieved if the ribs are formed at least on the separators 4, each housing one of the corresponding negative electrode plates 3, which are arranged on both sides of the electrode plate group 5. Of course, however, a plurality of ribs can be formed on the separators 4, each housing one of all the corresponding negative electrode plates 3. If the lead-acid battery 1 contains only a single cell chamber 6, a container of the lead-acid battery 1 can also serve as the cell chamber 6. First example

[0087] The design and advantages of the present invention are further described below with reference to examples of the present embodiment. It should be noted that the present invention is not limited to these examples. (1) Formation of a lead-acid battery

[0088] The lead-acid batteries 1 formed in the present examples are liquid lead-acid batteries with a size of D23L, as specified in JIS D 5301. Seven positive electrode plates 2 and eight negative electrode plates 3 are housed in each cell chamber 6, and each negative electrode plate 3 is housed in a pocket-shaped separator 4 made of polyethylene.

[0089] Table 5 presents the designs and characteristics of accumulators B2 to B8 of the present examples and of comparison accumulators A, B, B1 and B7 of comparison examples. [Table 5] Connection of the Sb foil Electrode plate with higher Sb concentration in the foil Al(MA%) contained in the electrolyte Short-distance driving mode (%) Positive electrode plate Negative electrode plate Area ratio (negative electrode / positive electrode) NS / PS Accumulator B1 trained trained 0,20 negative electrode not included 66 Accumulator B2 trained trained 0,30 negative electrode not included 70 Accumulator B3 trained trained 0,40 negative electrode not included 75 Battery B4 trained trained 0,50 negative electrode not included 75 Accumulator B5 trained trained 0,60 negative electrode not included 75 Accumulator B6 trained trained 0,80 negative electrode not included 70 Accumulator B7 trained trained 0,90 negative electrode not included 66 Accumulator A trained trained 1,00 negative electrode not included 45 Accumulator B trained not trained - - not included 40 Accumulator B8 trained trained 0,50 positive electrode not included 70 Accumulator B9 trained trained 0,50 negative electrode 0,1 80

[0090] The general design, in addition to the design shown in Table 5, is described below.

[0091] Each positive electrode plate 2 was formed in such a way that lead oxide powder is mixed with sulfuric acid and demineralized water to form a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0092] Each negative electrode plate 3 was formed in such a way that an organic additive, etc., is added to the lead oxide powder, the result is mixed with sulfuric acid and demineralized water to produce a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0093] A negative electrode grid is formed from an expanded metal grid of Pb-1.2Sn-0.1Ca using a rotary process, and a surface layer is formed from a Pb-3Ma%Sb foil (only in one eighth example, from a Pb-2Ma%Sb foil). Furthermore, a positive electrode grid is formed from an expanded metal grid of Pb-1.6Sn-0.1Ca using a reciprocating process, and a surface layer is formed from a Pb-2Ma%Sb foil (only in the case of accumulator B8, from a Pb-3Ma%Sb foil).

[0094] After the formed positive electrode plates 2 and the formed negative electrode plates 3 had matured and dried, the negative electrode plates 3 were each placed in the pocket-shaped separators 4 made of polyethylene, and then the negative electrode plates 3 and the positive electrode plates 2 were stacked alternately on top of each other. As a result, an electrode plate group 5 was formed in which the seven positive electrode plates 2 and the eight negative electrode plates 3 are stacked on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2 and 3. The electrode plate group 5 was placed in each of the six cell chambers 6, and a lead-acid battery 1 was formed in which six cells are connected in series.

[0095] An electrolyte consisting of dilute sulfuric acid with a density of 1.28 g / cm³3 The substance was introduced into the lead-acid battery 1, and subsequently a chemical transformation was carried out in a container. As a result, a lead-acid battery 1 with 12 V and 48 Ah was formed. (2) Evaluation of lead-acid battery characteristics: Evaluation of the characteristic value in short-distance driving mode

[0096] The trained lead-acid battery 1 underwent repeated charging / discharging cycles designed for short-distance driving mode to evaluate its performance characteristics in this mode. The ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 2.5 hours at 9.6 A, the lead-acid battery is left unattended for 24 hours. (B) Subsequently, a discharge is carried out over 40 seconds at a discharge current of 20 A. (C) Next, a charging cycle is performed for 60 seconds with a charging voltage of 14.2 V (a limited current of 50 A). (D) After the discharge (B) and charge (C) have been repeated 18 times, a discharge is carried out for 83.5 hours at a discharge current of 20 mA. (E) The cycles are repeated 20 times, with the discharge (B), the charging (C) and the discharge (D) being counted as a single cycle.

[0097] The state of charge (SOC) of the lead-acid battery after 20 cycles was measured, and such a value was considered as a characteristic value in the short-distance driving mode. (Area ratio of a negative electrode surface layer to a positive electrode surface layer)

[0098] The accumulator characteristics were compared between accumulators B1 to B7 and the reference accumulator A under the conditions that accumulators B1 to B7 and the reference accumulator A were identical, except that the area ratio NS / PS of the negative electrode surface layer to the positive electrode surface layer varied as a parameter.

[0099] As can be seen from Table 5, batteries B2 to B6, whose NS / PS ratio falls within the range of 0.3 to 0.8, exhibit a state of charge (SOC) equal to or greater than 70%, which defines the characteristic value in short-distance driving mode. For lead-acid batteries with such values, a sufficient lifetime characteristic can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling-stop vehicle is used in short-distance driving mode. In particular, batteries B3 to B5, whose NS / PS ratio falls within the range of 0.4 to 0.6, show excellent characteristics, as their SOC, which defines the characteristic value in short-distance driving mode, is equal to or greater than 75%. These batteries exhibit superior performance when the idling-stop vehicle is used in short-distance driving mode.

[0100] In contrast, battery B1, with a NS / PS ratio of 0.2, shows a low state of charge (SOC) of 66%, which indicates the characteristic value in short-distance driving mode. This may be due to an insufficient amount of Sb on the negative electrode side compared to the amount on the positive electrode side, thus reducing charge acceptance. However, this condition is within the range where it does not cause any problems in practical application.

[0101] The B7 battery, with a NS / PS ratio of 0.9, shows a low state of charge (SOC) of 66%, which is the characteristic value in short-distance driving mode. This could be because the amount of brine (Sb) on the negative electrode side is greater than the amount on the positive electrode side, thus accelerating water electrolysis and reducing the charging efficiency of the negative electrode plate. However, this condition is within the range where it does not cause any problems in practical application.

[0102] In contrast, the comparison battery A, whose NS / PS is 1, shows that the SOC, which indicates the characteristic value in the short-distance driving mode, has an extremely low value of 45%, thus enabling activation of the failsafe mechanism. As with battery B7, this may be due to the fact that the amount of Sb contained on the negative electrode side is greater than the amount of Sb contained on the positive electrode side, thus accelerating water electrolysis and reducing the charging efficiency of the negative electrode plate. (Absence / Presence of a negative electrode surface layer)

[0103] The comparison battery B, which includes the positive electrode surface layer but no surface layer on the negative electrode grid, shows that the state of charge (SOC), which indicates the characteristic value in short-distance driving mode, has an extremely low value of 40%, thus enabling activation of the failsafe mechanism. This may be due to the absence of a lead alloy foil on the surface of the negative electrode grid, resulting in no decrease in hydrogen overpotential and low charge acceptance.

[0104] Based on the above results, a lead-acid battery that reduces the activation of a failsafe mechanism and is adaptable for an idle-stop vehicle used in short-distance driving mode can be achieved by forming positive and negative electrode surface layers made of an antimony-containing lead alloy on the surfaces of positive and negative electrode grids that do not contain antimony, respectively, and by ensuring that the area of ​​the positive electrode surface layer is larger than that of the negative electrode surface layer. Furthermore, the characteristic value in short-distance driving mode is further improved by setting the area ratio NS / PS of the negative electrode surface layer to the positive electrode surface layer in the range of 0.30 to 0.90, and preferably in the range of 0.40 to 0.60. (Difference in Sb content between positive and negative electrode surface layers)

[0105] The B8 battery was developed from the B4 battery such that the negative electrode surface layer is made of a Pb-2Ma%Sb foil and the positive electrode surface layer is made of a Pb-3Ma%Sb foil. The B8 battery is inferior to the B4 battery because its state of charge (SOC), which indicates its performance in short-distance driving mode, is 70%. However, the B8 battery exhibits superior performance when the vehicle is used in short-distance driving mode. (Addition of aluminum ions)

[0106] To further improve charge absorption, the next step was to develop accumulator B9 from accumulator B4 by adding 0.1 wt% aluminum ions to the electrolyte of accumulator B4, and the characteristic value of accumulator B9 in the short-distance driving mode was evaluated.

[0107] As can be seen from Table 5, the SOC, which indicates the characteristic value in the short-distance driving mode, has an extremely high value of 80%, and the accumulator B9 exhibits a strongly preferred performance when the idle-stop vehicle is used in the short-distance driving mode. (Second comparative version)

[0108] Fig. Figure 2 is the schematic representation, which also illustrates an outline design of a lead-acid battery 1 of a second comparative design form.

[0109] With reference to Fig.2 is in the lead-acid battery 1 an electrode plate group 5 in which a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3 are stacked on top of each other, wherein a separator 4 is arranged between adjacent of the positive and negative electrode plates 2, 3, together with an electrolyte in each cell chamber 6.

[0110] The positive electrode plate 2 comprises a (not shown) positive electrode grid and a (not shown) positive electrode active material with which the positive electrode grid is filled, and the negative electrode plate 3 comprises a negative electrode grid 3a and a (not shown) negative electrode active material with which the negative electrode grid 3a is filled. It should be noted that the positive electrode grid and the negative electrode grid 3a of the present embodiment are made of lead or of a lead alloy that does not contain antimony (Sb), such as a Pb-Ca alloy, a Pb-Sn alloy, or a Pb-Sn-Ca alloy. The phrase "does not contain antimony" means that no antimony is added as an alloying element, and the case in which a raw material contains a small amount of antimony as an impurity is considered antimony-free.That is to say, in the case where antimony is an unavoidable impurity, the present invention contains no antimony.

[0111] The positive electrode plates 2 are connected in parallel to each other at ear sections 9 of the positive electrode grids by a positive electrode holder 7, and the negative electrode plates 3 are connected in parallel to each other at ear sections 10 of the negative electrode grids 3a by a negative electrode holder 8. The electrode plate groups 5, each housed in the cell chambers 6, are connected in series by a connector 11. The positive electrode holder 7 and the negative electrode holder 8, each housed in the cell chambers 6 located at both ends of the lead-acid battery 1, are each welded to terminals, and each terminal is welded to a corresponding positive and negative electrode connection 12, 13 arranged on a cover 14.

[0112] In the present comparative embodiment, the density of the positive electrode active material in the positive electrode plate 2 is equal to or greater than 3.6 g / ml and equal to or less than 4.8 g / ml. Furthermore, the total pore volume of the positive electrode active material is equal to or greater than 0.06 ml / g and equal to or less than 0.18 ml / g. The negative electrode plates 3 are arranged on both sides of the electrode plate group 5, and each negative electrode plate 3 is housed in one of the corresponding pocket-shaped separators 4.

[0113] If the density of the positive electrode active material is less than 3.6 g / ml or the total pore volume of the positive electrode active material is greater than 0.18 ml / g, the overall capacity of the lead-acid battery decreases, and therefore the battery life in the short-range driving mode for use during idling stops is reduced. Conversely, if the density of the positive electrode active material is greater than 4.8 g / ml or the total pore volume of the positive electrode active material is less than 0.06 ml / g, a decrease in state of charge (SOC) occurs at an early stage in the short-range driving mode for use during idling stops, and therefore the failsafe mechanism is frequently activated at an early stage.

[0114] Even if the density of the positive electrode active material falls into the range of 3.6 to 4.8 g / ml or the total pore volume of the positive electrode active material falls into the range of 0.06 to 0.18 ml / g, a decrease in state of charge (SOC) occurs at an early stage in the short-range driving mode as described above if each negative electrode plate 3 is not housed in a corresponding pocket-shaped separator 4. Since the inventors of the present invention first observed that the fail-safe mechanism is frequently activated at this early stage due to the occurrence of an early decrease in SOC, a detailed description of this follows.

[0115] Patent document 4 discloses that, in order to counteract a short lifetime caused by an increase in the frequency of discharge due to the operating conditions, where the frequency of temporary stopping accompanied by an idle stop is high, the density of a positive electrode active material is 3.5 to 4.5 g / cc, the specific gravity of an electrolyte is 1.240 to 1.260 (20 °C), and the amount of carbon, which is an additive to a negative electrode plate, is 0.5 to 2.0% per mass of a negative electrode active material.

[0116] Patent document 4 describes how the short service life is improved by repeated heavy discharges under the following conditions, and discloses, according to examples in patent document 4, that the service life is improved when testing repeated charging and heavy discharges if the three conditions mentioned above are met. However, no investigation has been conducted regarding the low frequency of use of idling stop vehicles in a short-distance driving mode. Furthermore, patent document 4 does not disclose the positions of the positive and negative electrode plates or the shape and position of a separator.

[0117] The inventors of the present invention have conducted various investigations into the fact that activation of a failsafe mechanism frequently occurs at an early stage due to a novel problem that had never previously occurred in a low-frequency, short-distance driving mode involving an idle-stop vehicle equipped with a lead-acid battery, i.e., due to an early occurrence of state of charge (SOC) depletion, which had never been observed, for example, in patent document 4. As a result, the following cause was identified: The idle-stop vehicle is not used on weekdays but only for short trips on weekends. Consequently, the SOC gradually decreases on weekdays due to low-current storage. Furthermore, the charging rate on weekends is insufficient compared to the discharging rate due to the use of the idle-stop vehicle in heavy traffic.

[0118] In response to the above, the inventors of the present invention have found that the above problem is overcome in such a way that the density or total pore volume of the positive electrode active material is determined as described above and that each negative electrode plate is accommodated in one of the corresponding pocket-shaped separators.

[0119] When each negative electrode plate 3 is housed in a corresponding pocket-shaped separator 4, the separator 4 is located at the boundary between the cell chamber and each of the negative electrode plates 3, which are arranged on both sides of the electrode plate group 5. Consequently, the electrolyte can enter the space between the separator 4 and the negative electrode plate 3 on the side where the separator 4 and the cell chamber are in contact. As a result, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle, which operates in a short-distance driving mode, activation of the failsafe mechanism can be more effectively reduced.

[0120] In the present comparative embodiment, a surface layer (not shown) consisting of an antimony-containing lead alloy is formed on a surface of the negative electrode grid 3a. The antimony-containing lead alloy has the effect of reducing hydrogen overpotential, thereby improving the charge acceptance of the lead-acid battery 1. It should be noted that the surface layer preferably consists of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%.

[0121] In the present comparative embodiment, the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. The sodium ions contained in the electrolyte have the effect of improving charge recovery after a deep discharge, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0122] In the present comparative embodiment, the W / L ratio preferably falls within a range of 0.50 to 0.80, where "L" represents the internal dimension of the cell chamber 6 in the stacking direction of the electrode plate groups 5, and "W" represents the total thickness of the positive and negative electrode plates 2, 3. The W / L value represents the size of the gap between the positive electrode plate 2 and the negative electrode plate 3, i.e., the measure of the amount of electrolyte entering such a gap. When the W / L value falls within a range of 0.50 to 0.80, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0123] In the present comparative embodiment, a plurality of ribs are preferably formed on an inner part of the separator 4 to create a certain gap between the negative electrode plate 3 and the separator 4. This allows the electrolyte to enter such a gap in each of the negative electrode plates 3, which are arranged on both sides of the electrode plate group 5, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for the idle stop vehicle, which operates in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0124] The above advantages can be achieved if the ribs are formed at least on the separators 4, each housing one of the corresponding negative electrode plates 3, which are arranged on both sides of the electrode plate group 5. Of course, however, a plurality of ribs can be formed on the separators 4, each housing one of all the corresponding negative electrode plates 3. If the lead-acid battery 1 contains only a single cell chamber 6, a container of the lead-acid battery 1 can also serve as the cell chamber 6.

[0125] Furthermore, in the present comparative design, the mass ratio M N / M P preferably in a range of 0.70 to 1.10 and preferably in a range of 0.80 to 1.0, wherein “M P “ represents the mass of the positive electrode active material per cell chamber 6 and “M N“represents the mass of the negative electrode active material per cell chamber 6. If the mass ratio M N / M P If the temperature difference between the negative electrode active material and the positive electrode active material falls within the range described above, a service life can be maintained, and the charge acceptance of lead-acid battery 1 can be improved. Even when lead-acid battery 1 is used for the idle stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can be further reduced. Second reference example(1) Training of a lead-acid battery

[0126] The lead-acid batteries 1 formed in the present examples are liquid lead-acid batteries with a size of D23L, as specified in JIS D 5301. Seven positive electrode plates 2 and eight negative electrode plates 3 are housed in each cell chamber 6, and a separator 4 is arranged between the positive electrode plate 2 and the negative electrode plate 3.

[0127] Table 6 presents the designs and characteristics of accumulators C1 to C18 of the examples and of comparison accumulators A to D of comparison examples. [Table 6] Density of the positive electrode active material (g / ml) Total pore volume of the positive electrode (ml / g) separator Na(mol / L) contained in the electrolyte Thickness ratio (W / L) Lifespan (frequency) Short-distance driving mode (%) Recovery after deep discharge (minutes) form Element to be accommodated rib Accumulator A 3,5 0,19 Bag negative electrode plate negative electrode side 0,11 0,65 18.000 75 3,5 Accumulator C1 3,6 0,18 Bag negative electrode plate negative electrode side 0,11 0,65 28.800 76 3,5 Accumulator C2 3,9 0,15 Bag negative electrode plate negative electrode side 0,11 0,65 39.600 76 3,5 Accumulator C3 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,65 46.800 78 3,5 C4 accumulator 4,5 0,09 Bag negative electrode plate negative electrode side 0,11 0,65 50.400 72 3,5 C5 accumulator 4,8 0,06 Bag negative electrode plate negative electrode side 0,11 0,65 54.000 67 3,5 Accumulator B 5 0,04 Bag negative electrode plate negative electrode side 0,11 0,65 57.600 45 3,5 Accumulator C 4,2 0,12 plate - negative electrode side 0,11 0,65 39.600 50 3,5 Accumulator D 4,2 0,12 Bag positive electrode plate negative electrode side 0,11 0,65 39.600 51 3,5 [Table 6] Density of the positive electrode active material (g / ml) Total pore volume of the positive electrode (ml / g) separator Na(mol / L) contained in the electrolyte Thickness ratio (W / L) Lifespan (frequency) Short-distance driving mode (%) Recovery after deep discharge (minutes) form Element to be accommodated rib C6 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,005 0,65 54.000 78 1,5 Accumulator C7 4,2 0,12 Bag negative electrode plate negative electrode side 0,01 0,65 50.400 76 3,1 C8 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,03 0,65 46.800 83 3,4 C9 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,28 0,65 46.800 75 3,5 C10 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,45 0,65 43.200 71 3,5 C11 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,56 0,65 39.600 65 3,5 [Table 6] Density of the positive electrode active material (g / ml) Total pore volume of the positive electrode (ml / g) separator Na(mol / L) contained in the electrolyte Thickness ratio (W / L) Lifespan (frequency) Short-distance driving mode (%) Recovery after deep discharge (minutes) form Element to be accommodated rib C12 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,45 39.600 69 3,5 C13 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,50 39.600 73 3,5 C14 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,60 43.200 78 3,5 C15 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,70 43.200 79 3,5 C16 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,80 39.600 72 3,5 C17 accumulator 4,2 0,12 Bag negative electrode plate negative electrode side 0,11 0,85 57.600 69 3,5 C18 accumulator 4,2 0,12 Bag negative electrode plate Positive electrode side 0,11 0,65 43.200 55 3,5

[0128] The general design, in addition to the design shown in Table 6, is described below.

[0129] Each positive electrode plate 2 was formed in such a way that lead oxide powder is mixed with sulfuric acid and demineralized water to form a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0130] Each negative electrode plate 3 was formed in such a way that an organic additive, etc., is added to the lead oxide powder, the result is mixed with sulfuric acid and demineralized water to produce a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0131] A negative electrode grid is formed from an expanded metal grid of Pb-1.2Sn-0.1Ca, and a surface layer is produced from a Pb-3Ma%Sb foil. In addition, a negative electrode grid is formed from an expanded metal grid of Pb-1.6Sn-0.1Ca, and no surface layer is formed.

[0132] After the formed positive electrode plates 2 and the formed negative electrode plates 3 had matured and dried, the negative electrode plates 3 and the positive electrode plates 2 were stacked alternately on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2. As a result, an electrode plate group 5 was formed in which the seven positive electrode plates 2 and the eight negative electrode plates 3 are stacked on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2 and 3. The electrode plate group 5 was placed in each of the six cell chambers 6, and lead-acid batteries of the examples and the comparison examples were formed, in each of which six cells are connected in series.

[0133] An electrolyte consisting of dilute sulfuric acid with a density of 1.28 g / cm³ 3 The substance was introduced into the lead-acid battery, and a chemical conversion was then carried out in a container. The result was a lead-acid battery with a capacity of 12 V and 48 Ah. <Messung der Dichte und des Gesamtporenvolumens eines Positivelektroden-Aktivmaterials>

[0134] The density and total pore volume of the positive electrode active material in the matured and dried positive electrode plates 2 were measured using a mercury intrusion technique (porosimeter).

[0135] A volume a of a sample (of the active material of the positive electrode plate) in the state in which mercury is allowed to penetrate under the conditions under which holes with a diameter equal to or greater than 5 µm are filled with the mercury was obtained, and a density b / a (g / ml) was obtained by dividing the mass b of the sample by the volume a.

[0136] When obtaining volumes corresponding to different hole diameters of samples (of the active material of the positive electrode plate) under different conditions for mercury penetration, the sum c of the volumes of holes with a diameter equal to or greater than 0.003 µm and equal to or less than 180 µm and a total pore volume c / b (ml / g) were obtained by dividing the sum c by the mass b of the sample. (2) Evaluation of lead-acid battery characteristics (2-1) Evaluation of the lifetime characteristic

[0137] The trained lead-acid battery underwent repeated charging / discharging cycles designed for an idle stop in order to evaluate the battery's lifespan characteristic.

[0138] A lifetime rating test was performed under the following conditions, essentially in accordance with the Storage Battery Association standard (SBA S 0101). It should be noted that the ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 59 seconds at a discharge current of 45 A is performed, a discharge over 1 second at 300 A is performed. (B) Subsequently, charging is carried out for 60 seconds with a charging voltage of 14.2 V (a limited current of 100 A). (C) Every 3,600 cycles, the lead-acid battery is left unattended for 48 hours, with the discharge (A) and charging (B) counted as one cycle, and then the cycles are resumed.

[0139] The above cycles were repeated, and the number of cycles in which the discharge voltage fell below 7.2 V was considered the lifetime indicator. It should be noted that in the above test, water was not added until after 30,000 cycles. (2-2) Evaluation of the characteristic value in short-distance driving mode

[0140] The trained lead-acid battery 1 underwent repeated charging / discharging cycles designed for short-distance driving mode to evaluate its performance characteristics in this mode. The ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 2.5 hours at 9.6 A, the lead-acid battery is left unattended for 24 hours. (B) Subsequently, a discharge is carried out over 40 seconds at a discharge current of 20 A. (C) Subsequently, charging is carried out for 60 seconds with a charging voltage of 14.2 V (a limited current of 50 A). (D) After the discharge (B) and charge (C) have been repeated 18 times, a discharge is carried out for 83.5 hours at a discharge current of 20 mA. (E) The cycles are repeated 20 times, with the discharge (B), the charging (C) and the discharge (D) being counted as a single cycle.

[0141] The state of charge (SOC) of the lead-acid battery after 20 cycles was measured, and such a value was considered as a characteristic value in the short-distance driving mode. (2-3) Charge recovery after deep discharge (A) A discharge is carried out at a current with a five-hour rate (a discharge current of 9.8 A) down to 10.5 V. (B) Subsequently, a discharge is carried out under a load of 10 W for 14 days at a temperature of 40 °C ± 2 0Procedure C is performed, and then the lead-acid battery is left unattended with the circuit interrupted for 14 days. (C) Subsequently, charging is carried out for four hours at a temperature of 25 °C ± 3 °C with a charging voltage of 15.0 V (a limited current of 25 A). (D) The lead-acid battery is then left unattended for 16 hours or longer in an atmosphere of -15 °C ± 1 °C, and then discharged at 300 A to 6.0 V.

[0142] The time it takes for the lead-acid battery voltage to reach 6.0 V was evaluated as the state of charge (SOC) recovery after a deep discharge.

[0143] This assessment of charge recovery after deep discharge was based on the following assumption: If the lead-acid battery, which has been revived after entering a deep discharge state, is reused in short-distance driving mode, such that a charge / discharge cycle is repeated, and the battery's charge recovery is poor, the state of charge (SOC) will decrease further due to a reduction in charge capacity and a decrease in the reaction surface area. Consequently, the failsafe mechanism will be activated more frequently. (Density and total pore volume of a positive electrode active material)

[0144] The accumulator parameters were compared between accumulators C1 to C5 and the reference accumulators A, B under the conditions that accumulators C1 to C5 and reference accumulators A, B were identical, except that the density and total pore volume of the positive electrode active material varied as parameters.

[0145] As can be seen from Table 6, batteries C1 to C5, where the density of the positive electrode active material falls within the range of 3.6 to 4.8 g / ml or the total pore volume of the positive electrode active material falls within the range of 0.06 to 0.18 ml / g, exhibit that the lifetime rating is equal to or greater than 28,000 and that the SOC, which indicates the rating in the short-distance driving mode, is equal to or greater than 70%. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in the short-distance driving mode.In particular, batteries C2 to C4, where the density of the positive electrode active material falls within the range of 3.9 to 4.5 g / ml or the total pore volume of the positive electrode active material falls within the range of 0.09 to 0.15 ml / g, exhibit excellent characteristics, as the lifetime rating is equal to or greater than 39,000, and the state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 75%. These batteries demonstrate superior performance when the idling vehicle is used in short-distance driving mode.

[0146] In contrast, the comparison battery A, where the density of the positive electrode active material is 3.5 g / ml (lower than 3.6 g / ml) or the total pore volume of the positive electrode active material is 0.19 ml / g (exceeding 0.18 ml / g), shows that the SOC, which indicates the characteristic value in the short-distance driving mode, is 75%, but it shows that the lifetime characteristic has a low value of 18,000. This may be due to the positive electrode active material softening during charging / discharging and falling out of the electrode plate, thus reducing the overall capacity of the battery.

[0147] The comparison battery B, where the density of the positive electrode active material is 5 g / ml (exceeding 4.8 g / ml) or the total pore volume of the positive electrode active material is 0.04 ml / g (less than 0.06 ml / g), shows that the lifetime rating is an excellent 57,600. However, it also shows that the state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 45%. This may be because the positive electrode active material is too dense, preventing sufficient electrolyte from penetrating the positive electrode to contribute to charging / discharging. (Separator shape)

[0148] The following accumulators were constructed from accumulator C3 of the example: a comparison accumulator C of the comparison example, which differs from accumulator C3 of the example only in that one separator is plate-shaped rather than pocket-shaped (i.e., the separator does not surround a negative electrode plate but is merely positioned between a positive electrode plate and the negative electrode plate); and a comparison accumulator D of the comparison example, in which not every negative electrode plate is housed in a corresponding separator, but each positive electrode is housed in a corresponding separator. An evaluation was performed for these accumulators (see Table 6).

[0149] The comparison battery C shows that the lifetime rating has an excellent value of 39,600, but it shows that the SOC, which indicates the rating in the short-distance driving mode, has a low value of 50%.

[0150] As with the comparison battery C, the comparison battery D also shows that the SOC, which indicates the characteristic value in the short-distance driving mode, has a low value of 51%.

[0151] The characteristic value in short-distance driving mode can be reduced for the following reasons, as described above. Unlike the C3 battery, the negative electrode plate is in close contact with an inner wall of the cell chamber, and the electrolyte cannot enter the interface between them. In this way, a portion of the negative electrode's active material is not used, leading to a reduction in charge acceptance. (Na concentration in the electrolyte)

[0152] Batteries C6 to C11 were designed from the example battery C3 such that the sodium ion concentration in the electrolyte fluctuates between 0.005 and 0.56 mol / L. The lifetime rating of each battery and its performance in short-distance driving mode were evaluated.

[0153] The concentration of Na ions in the electrolyte was adjusted so that the amount of sodium sulfate to be added to the electrolyte changed.

[0154] As can be seen from Table 6, batteries C7 to C10, whose sodium ion content in the electrolyte ranges from 0.01 to 0.45 mol / L, exhibit a lifetime rating of 43,000 or greater, a state of charge (SOC) that indicates the rating in short-distance driving mode of 70% or greater, and a recovery time after deep discharge of 3 minutes or more. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idle-stop vehicle is used in short-distance driving mode. In particular, batteries C3, C8, and C9, whose sodium ion content in the electrolyte ranges from 0.03 to 0.28 mol / L, show excellent ratings, as their lifetime rating is 46 or greater.The battery has a state of charge (SOC) of 75% or higher, indicating a value in short-distance driving mode, and a recovery time after deep discharge of 3 minutes or more. These batteries exhibit superior performance when the vehicle is used in short-distance driving mode.

[0155] In contrast, the C6 battery, whose sodium ion concentration in the electrolyte is 0.005 mol / L, shows a low recovery time of 1.5 minutes after deep discharge. This may be due to reduced conductivity during deep discharge caused by a low number of sodium ions.

[0156] The C11 battery, with a sodium ion concentration of 0.56 mol / L in the electrolyte, shows a low state of charge (SOC) of 65%, which indicates the characteristic value in short-distance driving mode. This may be due to reduced charge acceptance resulting from a high number of sodium ions.

[0157] Based on the above results, recovery after a deep discharge is improved by ensuring that the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. Even when the lead-acid battery is used for the idle-stop vehicle operating in short-distance driving mode, this effectively reduces the activation of the failsafe mechanism. (ratio of total electrode plate thickness to cell chamber width)

[0158] Batteries C12 to C17 were configured from the example battery C3 such that the W / L ratio varies between 0.45 and 0.85, where "L" represents the internal dimension of the cell chamber in the stacking direction of the electrode plate groups and "W" represents the total thickness of the positive and negative electrode plates. The lifetime rating of each battery and its short-range driving performance were evaluated.

[0159] Fig.Figure 3 is the cross-sectional view of cell chamber 6. The internal dimension of cell chamber 6 in the stacking direction of the electrode plate groups, each housed in cell chamber 6, is represented by “L”, the thickness of the positive electrode plate 2 is represented by “W1”, the thickness of the negative electrode plate 3 is represented by “W2”, and the total thickness (W1 x 7 + W2 x 8) of the positive electrode plates 2 and the negative electrode plates 3 is represented by “W”.

[0160] As can be seen from Table 6, batteries C3, C13 to C16, whose W / L ratio falls within the range of 0.50 to 0.80, show that their lifetime rating is equal to or greater than 39,000 and that their state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 70%. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in short-distance driving mode. In particular, batteries C3, C14, and C15, whose W / L ratio falls within the range of 0.60 to 0.70, show excellent ratings, as their lifetime rating is equal to or greater than 43,000 and their state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 75%.These batteries exhibit preferred performance when the idling stop vehicle is used in short-distance driving mode.

[0161] In contrast, the C12 battery, with a W / L ratio of 0.45, shows a lifetime rating of 39,600 hours, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 69%. This may be due to reduced charge acceptance resulting from a lack of active material.

[0162] Battery C17, with a W / L ratio of 0.85, shows a lifetime rating of 57,600, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 69%. This may be due to reduced charge acceptance caused by a lack of electrolyte entering the spaces between adjacent cells in battery C17.

[0163] Based on the above results, the charge acceptance is further improved so that the W / L ratio is set in the range of 0.50 to 0.80, and preferably in the range of 0.60 to 0.70. Even when the lead-acid battery is used for the idle-stop vehicle operating in short-distance driving mode, this effectively reduces the activation of the failsafe mechanism. (Ribs formed on a separator)

[0164] To improve charge uptake, the following was considered with reference to Fig.3. The majority of ribs 15 are formed on the inner part of the separator 4 in the accumulator C3 to create a certain gap between the negative electrode plate 3 and the pocket-shaped separator 4 in which the negative electrode plate 3 is housed. To confirm the effectiveness of the ribs 15, the accumulator C18 was configured such that the ribs 15 were not positioned opposite the negative electrode plates 3, but rather opposite the positive electrode plates 2, and an evaluation was performed on the accumulator C18. It should be noted that the height of the rib 15 was 0.2 mm and that it was formed integrally with the separator 4.

[0165] As can be seen from Table 6, the C3 battery, in which the ribs are configured to face the negative electrode plates, exhibits a lifetime rating of 46,000 or greater and a state of charge (SOC) of 75% or greater, which indicates the rating in short-distance driving mode. With such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idle-stop vehicle is used in short-distance driving mode.

[0166] In contrast, battery C18, in which the ribs are designed to face the positive electrode plates, exhibits a low state of charge (SOC) of 55%, which indicates the characteristic value in short-distance driving mode. This can be attributed to the following: When the negative electrode plates, located on both sides of the electrode plate assembly, are pressed against the inner walls of the cell chamber, no gap is formed between the negative electrode plate and the cell chamber. Consequently, charge acceptance is reduced due to a lack of electrolyte entering the space between adjacent cells in battery C18.

[0167] Based on the above results, the charge acceptance of the lead-acid battery is further improved by housing each negative electrode plate in a corresponding pocket-shaped separator, and by forming ribs on the inner part of the separator to create a certain gap between the negative electrode plate and the separator. Even when the lead-acid battery is used in the idle-stop vehicle operating in short-distance driving mode, this effectively reduces the activation of the failsafe mechanism.

[0168] In the present embodiment, tin sulfate can be added to the positive electrode. The tin sulfate is preferably added to the positive electrode because this improves the discharge capacity. (Second embodiment)

[0169] Fig.Figure 2 is a schematic representation which also illustrates an outline design of a lead-acid battery 1 of a second embodiment of the present invention.

[0170] With reference to Fig. 2 is in the lead-acid battery 1 an electrode plate group 5 in which a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3 are stacked on top of each other, wherein a separator 4 is arranged between adjacent of the positive and negative electrode plates 2, 3, together with an electrolyte in each cell chamber 6.

[0171] The positive electrode plate 2 comprises a positive electrode grid and a positive electrode active material with which the positive electrode grid is filled, and the negative electrode plate 3 comprises a negative electrode grid and a negative electrode active material with which the negative electrode grid is filled. It should be noted that the positive and negative electrode grids of the present embodiment are made of lead or of a lead alloy that does not contain antimony (Sb), such as a Pb-Ca alloy, a Pb-Sn alloy, or a Pb-Sn-Ca alloy.

[0172] The positive electrode plates 2 are connected in parallel to each other at ear sections 9 of the positive electrode grids by a positive electrode holder (an electrode plate connecting plate) 7, and the negative electrode plates 3 are connected in parallel to each other at ear sections 10 of the negative electrode grids by a negative electrode holder (electrode plate connecting plate) 8. The electrode plate groups 5, each housed in the cell chambers 6, are connected in series by a connector 11. The positive electrode holder 7 and the negative electrode holder 8, each housed in the cell chambers 6 located at both ends of the lead-acid battery 1, are each welded to terminals, and each terminal is welded to a corresponding positive and negative electrode connection 12, 13 arranged on a cover 14.

[0173] In the present embodiment, a surface layer (not shown) consisting of an antimony-containing lead alloy is formed on a surface of the negative electrode grid. The antimony-containing lead alloy has the effect of reducing hydrogen overpotential, thereby improving the charge acceptance of the lead-acid battery 1. It should be noted that the surface layer consists of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%.

[0174] Furthermore, in the present embodiment, a mass ratio M S / M P in a range of 0.50 to 0.74 and preferably a range of 0.57 to 0.70, wherein “M P “ represents the mass of the positive electrode active material per cell chamber 6 and “Ms” represents the mass of sulfuric acid contained in the electrolyte. If the mass ratio M S / MP If the concentration of sulfuric acid in the positive electrode active material falls within the range mentioned above, a service life value can be maintained, and the charge acceptance of the lead-acid battery 1 can be improved. Even if the lead-acid battery 1 is used for an idle-stop vehicle operating in a short-distance driving mode, this can reduce the activation of a failsafe mechanism.

[0175] In the present embodiment, the W / L ratio preferably falls within a range of 0.50 to 0.80, where "L" represents the internal dimension of the cell chamber 6 in the stacking direction of the electrode plate groups 5, and "W" represents the total thickness of the positive and negative electrode plates 2, 3. The W / L value represents the size of the gap between the positive electrode plate 2 and the negative electrode plate 3, i.e., the measure of the amount of electrolyte entering such a gap. When the W / L value falls within a range of 0.50 to 0.80, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0176] In the present embodiment, the density of the positive electrode active material is preferably set in a range of 3.6 to 4.8 g / ml and more preferably in a range of 3.9 to 4.5 g / ml. This further improves the charge acceptance of the lead-acid battery 1. Consequently, even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can be more effectively reduced.

[0177] In the present embodiment, the electrode plate connecting plates (holders) 7, 8 and the connector 11 are preferably made of a lead alloy that contains no antimony and contains tin. Since the electrode plate connecting plates (holders) 7, 8 and the connector 11 (hereinafter referred to as the "connecting element") do not contain antimony, corrosion of the ear parts 9, 10 due to antimony elution into the electrolyte is reduced. In this way, the service life of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle, which operates in a short-distance driving mode, activation of the failsafe mechanism can be more effectively reduced. Second example

[0178] The design and advantages of the present invention are further described below with reference to examples of the present embodiment. (1) Formation of a lead-acid battery

[0179] The lead-acid batteries 1 formed in the present examples are liquid lead-acid batteries with a size of D23L, as specified in JIS D 5301. Seven positive electrode plates 2 and eight negative electrode plates 3 are housed in each cell chamber 6, and each negative electrode plate 3 is housed in a corresponding pocket-shaped separator 4 made of polyethylene.

[0180] Each positive electrode plate 2 was formed in such a way that lead oxide powder is mixed with sulfuric acid and demineralized water to form a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0181] Each negative electrode plate 3 was formed in such a way that an organic additive, etc., is added to the lead oxide powder, the result is mixed with sulfuric acid and demineralized water to produce a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0182] After the formed positive electrode plates 2 and the formed negative electrode plates 3 had matured and dried, the negative electrode plates 3 were each placed in the pocket-shaped separators 4 made of polyethylene, and then the negative electrode plates 3 and the positive electrode plates 2 were stacked alternately on top of each other. As a result, an electrode plate group 5 was formed in which the seven positive electrode plates 2 and the eight negative electrode plates 3 are stacked on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2 and 3. The electrode plate group 5 was placed in each of the six cell chambers 6, and a lead-acid battery 1 was formed in which six cells are connected in series.

[0183] An electrolyte consisting of dilute sulfuric acid with a density of 1.28 g / cm³3 The substance was introduced into the lead-acid battery 1, and subsequently a chemical transformation was carried out in a container. As a result, a lead-acid battery 1 with 12 V and 48 Ah was formed. (2) Evaluation of lead-acid battery characteristics (2-1) Evaluation of the lifetime characteristic

[0184] The trained lead-acid battery underwent repeated charging / discharging cycles designed for an idle stop in order to evaluate the battery's lifespan characteristic.

[0185] A lifetime rating test was performed under the following conditions, essentially in accordance with the Storage Battery Association standard (SBA S 0101). It should be noted that the ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 59 seconds at a discharge current of 45 A is performed, a discharge over 1 second at 300 A is performed. (B) Subsequently, charging is carried out for 60 seconds with a charging voltage of 14.2 V (a limited current of 100 A). (C) The lead-acid battery is left unattended for 48 hours every 3,600 cycles, with the discharge (A) and charging (B) counted as one cycle, and then the cycles are resumed.

[0186] The above cycles were repeated, and the number of cycles in which the discharge voltage fell below 7.2 V was considered the lifetime indicator. It should be noted that in the above test, water was not added until after 30,000 cycles. (2-2) Evaluation of the characteristic value in short-distance driving mode

[0187] The trained lead-acid battery 1 underwent repeated charging / discharging cycles designed for short-distance driving mode to evaluate its performance characteristics in this mode. The ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 2.5 hours at 9.6 A, the lead-acid battery is left unattended for 24 hours. (B) A discharge is carried out over 40 seconds at a discharge current of 20 A. (C) Charging is carried out over 60 seconds with a charging voltage of 14.2 V (a limited current of 50 A). (D) After the discharge (B) and charge (C) have been repeated 18 times, a discharge is carried out for 83.5 hours at a discharge current of 20 mA. (E) The cycles are repeated 20 times, with the discharge (B), the charging (C) and the discharge (D) being counted as a single cycle.

[0188] The state of charge (SOC) of the lead-acid battery after 20 cycles was measured, and such a value was considered as a characteristic value in the short-distance driving mode. (Example 4-1)

[0189] Accumulators D1 to D7 were formed, in each of which a surface layer consisting of an antimony-containing lead alloy is formed on a surface of a negative electrode grid and a mass ratio M S / M P falls within a range of 0.45 to 0.98, where "M P “Represents the mass of a positive electrode active material per cell chamber and “Ms” represents sulfuric acid contained in an electrolyte. The lifetime rating of each battery and the rating of each battery in the short-distance driving mode were evaluated.

[0190] The negative electrode grid is formed from an expanded metal lattice of Pb-1.2Sn-0.1Ca, and the surface layer is made from a Pb-3Ma%Sb foil. In addition, a positive electrode grid is formed from an expanded metal lattice of Pb-1.6Sn-0.1Ca, and no surface layer is formed on the positive electrode grid.

[0191] To determine the mass ratio M S / M P To adjust the parameters, the mass of the positive electrode active material was changed in a range of 1.5 to 2.5 mol, and the mass of sulfuric acid was changed in a range of 2.4 to 3.6 mol.

[0192] Table 7 presents the evaluation results for each characteristic value. It should be noted that a D8 accumulator, in which no surface layer is formed on the surface of a negative electrode grid, was used as a comparison example. [Table 7] Mass ratio of sulfuric acid to positive electrode active material M S / M P Negative electrode plate Key figure in short-distance driving mode SOC (%) Lifetime characteristic (frequency) Negative electrode grid surface layer Accumulator D1 0,45 Pb-Sn-Ca Pb-Sb 58 43.200 Accumulator D2 0,50 Pb-Sn-Ca Pb-Sb 71 43.200 D3 accumulator 0,57 Pb-Sn-Ca Pb-Sb 74 43.200 D4 accumulator 0,66 Pb-Sn-Ca Pb-Sb 75 43.200 D5 accumulator 0,70 Pb-Sn-Ca Pb-Sb 74 43.200 Accumulator D6 0,74 Pb-Sn-Ca Pb-Sb 71 36.000 Accumulator D7 0,98 Pb-Sn-Ca Pb-Sb 72 18.000 Accumulator D8 0,66 Pb-Sn-Ca not trained 49 39.600

[0193] As can be seen from Table 7, the accumulators D2 to D6, whose mass ratio M S / M P If the value falls within the range of 0.50 to 0.74, the lifetime rating is equal to or greater than 36,000, and the SOC, which indicates the rating in short-distance driving mode, is equal to or greater than 71%, then a sufficient lifetime rating can be maintained for lead-acid batteries exhibiting such values. This also reduces the activation of the failsafe mechanism, even when the idling stop vehicle is used in short-distance driving mode. Specifically, batteries D3 to D5, whose mass ratio M S / M PThese batteries, falling within the range of 0.57 to 0.70, exhibit excellent characteristics, as their lifetime rating is equal to or greater than 43,200 and their state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 74%. These batteries demonstrate superior performance when the vehicle is used in short-distance driving mode.

[0194] In contrast, the accumulator D1, whose mass ratio M S / M P The value is 0.45, indicating a lifetime rating of 43,200, but it shows that the SOC, which represents the rating in short-distance driving mode, has a low value of 58%. This can be due to the following reasons: Since the amount of electrolyte is insufficient compared to the amount of positive electrode active material, a charging reaction does not occur adequately, and therefore the charge acceptance is reduced.

[0195] Furthermore, the accumulator D7, whose mass ratio M S / M P The value of 0.98 indicates that the SOC, which represents the characteristic value in short-distance driving mode, is 72%, but it shows that the lifetime characteristic has a low value of 18,000. This can be due to the following reasons: Since the amount of positive electrode active material is insufficient compared to the amount of electrolyte, the positive electrode active material softens. Repeated charging / discharging weakens the bond between the positive electrode active materials, and therefore the positive electrode plate deteriorates.

[0196] The D8 battery, in which no surface layer is formed on the negative electrode grid, shows a lifetime rating of 39,600 hours. However, it exhibits an extremely low state of charge (SOC) of 49%, which indicates the rating in short-distance driving mode. This can be attributed to the following: Because the lead-containing foil is not formed on the surface of the negative electrode grid, the hydrogen overpotential does not decrease, and therefore the charge acceptance is low.

[0197] Based on the above results, a lead-acid battery that reduces the activation of a failsafe mechanism and is adaptable for an idle-stop vehicle used in short-distance driving mode can be achieved by forming a surface layer consisting of an antimony-containing lead alloy on the surface of a negative electrode grid that does not contain antimony, and by ensuring that the mass ratio M S / M P of sulfuric acid contained in an electrolyte, to a positive electrode active material in a range of 0.50 to 0.74 and preferably in a range of 0.57 to 0.70. (Example 4-2)

[0198] To further improve charge acceptance, accumulators D9 to D15 were configured from accumulator D4 as described in Example 4-1 such that the W / L ratio varies between 0.45 and 0.85, where "L" represents the internal dimension of the cell chamber in the stacking direction of the electrode plate groups and "W" represents the total thickness of the positive and negative electrode plates. The lifetime rating of each accumulator and its short-range driving performance were evaluated. Accumulator D12 is identical to accumulator D4 as described in Example 4-1.

[0199] Fig.Figure 3 is the cross-sectional view of cell chamber 6. The internal dimension of cell chamber 6 in the stacking direction of the electrode plate groups, each housed in cell chamber 6, is represented by “L”, the thickness of the positive electrode plate 2 is represented by “W1”, the thickness of the negative electrode plate 3 is represented by “W2”, and the total thickness (W1 x 7 + W2 x 8) of the positive electrode plates 2 and the negative electrode plates 3 is represented by “W”.

[0200] Table 8 presents the evaluation results for each indicator. [Table 8] Mass ratio of sulfuric acid to positive electrode active material M S / M P Negative electrode plate Thickness ratio of the electrode plates to the cell chamber Key figure in short-distance driving mode: SOC (%) Lifetime characteristic (frequency) Negative electrode grid surface layer Accumulator D9 0,66 Pb-Sn-Ca Pb-Sb 0,45 63 36.000 Accumulator D10 0,66 Pb-Sn-Ca Pb-Sb 0,50 71 36.000 Accumulator D11 0,66 Pb-Sn-Ca Pb-Sb 0,60 74 39.600 D12 accumulator 0,66 Pb-Sn-Ca Pb-Sb 0,65 75 43.200 Accumulator D13 0,66 Pb-Sn-Ca Pb-Sb 0,70 74 39.600 Accumulator D14 0,66 Pb-Sn-Ca Pb-Sb 0,80 71 36.000 Accumulator D15 0,66 Pb-Sn-Ca Pb-Sb 0,85 61 36.000

[0201] As can be seen from Table 8, batteries D10 to D14, whose W / L ratio falls within the range of 0.50 to 0.80, show that their lifetime rating is equal to or greater than 36,000 and that their state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 71%. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in short-distance driving mode. In particular, batteries D11 to D13, whose W / L ratio falls within the range of 0.60 to 0.70, show excellent ratings, as their lifetime rating is equal to or greater than 39,600 and their state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 74%.These batteries exhibit preferred performance when the idling stop vehicle is used in short-distance driving mode.

[0202] In contrast, the D9 battery, with a W / L ratio of 0.45, shows a lifetime rating of 36,000, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 63%. This may be due to an insufficient amount of active material in the negative electrode compared to the positive electrode, resulting in reduced charge acceptance.

[0203] The D15 battery, with a W / L ratio of 0.85, shows a lifetime rating of 36,000, but its state of charge (SOC), which indicates the rating in short-distance driving mode, is low at 61%. This may be due to reduced charge acceptance caused by a lack of electrolyte entering the spaces between adjacent cells in the D15 battery.

[0204] Based on the above results, the charge acceptance can be further improved so that the W / L ratio is set in the range of 0.50 to 0.80, and preferably in the range of 0.60 to 0.70. Even when the lead-acid battery is used for the idle-stop vehicle operating in short-distance driving mode, this can more effectively reduce the activation of the failsafe mechanism. (Example 4-3)

[0205] To further improve charge uptake, accumulators D16 to D22 were subsequently formed from accumulator D4 formed in Example 4-1 such that the density of the positive electrode active material varied between 3.5 and 5.0 g / ml. It should be noted that accumulator D19 is identical to accumulator D4 formed in Example 4-1. Furthermore, the density of the positive electrode active material represents the density after a chemical transformation and was measured using the following procedure. Additionally, the total pore volume of the positive electrode was also measured in relation to the density of each positive electrode active material. <Messung der Dichte eines Positivelektroden-Aktivmaterials>

[0206] A volume a of a sample (of the active material of the positive electrode plate) was obtained using a mercury intrusion technique (porosimeter) in the state in which mercury is allowed to penetrate under conditions under which holes with a diameter equal to or greater than 5 µm are filled with the mercury, and a density (also called "bulk density") b / a (g / ml) was obtained by dividing the mass b of the sample by the volume a. <Messung des Gesamtporenvolumens einer positiven Elektrode>

[0207] When obtaining volumes corresponding to different hole diameters of samples (of the active material of the positive electrode plate) under different conditions for mercury penetration using the mercury intrusion technique (porosimeter), the sum c of the volumes of holes with a diameter equal to or greater than 0.003 µm and equal to or less than 180 µm and a total pore volume c / b (ml / g) were obtained by dividing the sum c of the pore volumes by the mass b of the sample.

[0208] Table 9 presents the evaluation results for each indicator. [Table 9] Mass ratio of sulfuric acid to positive electrode active material M S / M P Negative electrode plate Density of the positive electrode active material (g / ml) Total pore volume of the positive electrode (ml / g) Key figure in short-distance driving mode: SOC (%) Lifetime characteristic (frequency) Negative electrode grid surface layer Accumulator D16 0,66 Pb-Sn-Ca Pb-Sb 3,5 0,19 75 28.800 Accumulator D17 0,66 Pb-Sn-Ca Pb-Sb 3,6 0,18 74 36.000 Accumulator D18 0,66 Pb-Sn-Ca Pb-Sb 3,9 0,15 75 39.600 Accumulator D19 0,66 Pb-Sn-Ca Pb-Sb 4,2 0,12 75 43.200 D20 accumulator 0,66 Pb-Sn-Ca Pb-Sb 4,5 0,09 74 43.200 Accumulator D21 0,66 Pb-Sn-Ca Pb-Sb 4,8 0,06 71 43.200 D22 accumulator 0,66 Pb-Sn-Ca Pb-Sb 5,0 0,04 55 43.200

[0209] As can be seen from Table 9, batteries D17 to D21, where the density of the positive electrode active material falls within the range of 3.6 to 4.8 g / ml (the total pore volume of the positive electrode falls within the range of 0.06 to 0.18 ml / g), exhibit that the lifetime rating is equal to or greater than 36,000 and that the SOC, which indicates the rating in the short-distance driving mode, is equal to or greater than 71%. For lead-acid batteries exhibiting such values, a sufficient lifetime rating can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in the short-distance driving mode.In particular, the D18 to D20 batteries, where the density of the positive electrode active material falls within the range of 3.9 to 4.5 g / ml (the total pore volume of the positive electrode falls within the range of 0.09 to 0.15 ml / g), exhibit excellent lifetime characteristics, as the lifetime rating is equal to or greater than 39,600, and the state of charge (SOC), which indicates the rating in short-distance driving mode, is equal to or greater than 74%. These batteries demonstrate superior performance when the vehicle is used in short-distance driving mode.

[0210] In contrast, the D16 battery, in which the density of the positive electrode active material is 3.5 g / ml (the total pore volume of the positive electrode is 0.19 ml / g), shows that the SOC, which indicates the characteristic value in the short-distance driving mode, is 75%, but it shows that the lifetime characteristic value is low at 28,800. This may be due to a weakening of the bond between the positive electrode active materials and therefore a deterioration of the positive electrode plate.

[0211] The D22 battery, in which the density of the positive electrode active material is 5.0 g / ml (the total pore volume of the positive electrode is 0.04 ml / g), shows a lifetime rating of 43,200, but it also shows a low state of charge (SOC) of 55%, which indicates the rating in short-distance driving mode. This may be due to the positive electrode active material being too dense, thus reducing charge acceptance because of a lack of electrolyte entering the spaces between adjacent cells in the D22 battery.

[0212] Based on the above results, the density of the positive electrode active material is set in the range of 3.6 to 4.8 g / ml (the total pore volume of the positive electrode is set in the range of 0.06 to 0.18 ml / g) and preferably in the range of 3.9 to 4.5 g / ml (the total pore volume of the positive electrode is preferably set in the range of 0.09 to 0.15 ml / g). This maintains a sufficient lifetime characteristic and further improves charge acceptance. Even when the lead-acid battery is used for the idle-stop vehicle, which operates in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced. (Example 4-4)

[0213] To further improve the lifetime rating, an accumulator D23 was next constructed from the accumulator D4 designed in Example 4-1, such that the designs of the connecting elements (the electrode plate connecting plates (holders)) 7, 8 and the connector 11 were modified. The lifetime rating of each of the accumulators D4 and D23, and the rating of each of the accumulators D4 and D23 in the short-distance driving mode, were evaluated.

[0214] The connecting elements of the D23 accumulator are made of an antimony-containing lead alloy (Pb-2.7Sb), and the connecting elements of the D4 accumulator are made of a lead alloy (Pb-2.5Sn) that does not contain antimony and contains tin.

[0215] Table 10 presents the evaluation results for each indicator. [Table 10] Mass ratio of sulfuric acid to positive electrode active material M S / M P Negative electrode plate Connecting element Key figure in short-distance driving mode SOC (%) Lifetime characteristic (frequency) Negative electrode grid surface layer Accumulator D4 0,66 Pb-Sn-Ca Pb-Sb Pb-Sn 75 43.200 Accumulator D23 0,66 Pb-Sn-Ca Pb-Sb Pb-Sb 74 28.800

[0216] As can be seen from Table 10, the accumulator D4, which contains connecting elements made of the lead alloy that does not contain antimony and contains tin, shows a higher lifetime rating compared to that of the accumulator D23, which contains connecting elements made of the antimony-containing lead alloy. This may be because the connecting elements of accumulator D4 do not contain antimony and therefore corrosion of the ear parts 9, 10 due to elution of antimony into the electrolyte is reduced.

[0217] Based on the above results, the service life is further improved by making the electrode plate connection plates and connecting elements, including the connectors, from a lead alloy that contains no antimony and contains tin. Even when the lead-acid battery is used in an idle-stop vehicle operating in short-distance driving mode, this effectively reduces the activation of the failsafe mechanism.

[0218] It should be noted that poles for connecting the electrode plate connecting plates and external terminals to each other can be provided as connecting elements and can be made of a lead alloy that does not contain antimony and contains tin. (Third comparative form)

[0219] Fig.Figure 2 is the schematic representation, which also illustrates an outline design of a lead-acid battery 1 of a third comparative design form.

[0220] With reference to Fig. 2 is in the lead-acid battery 1 an electrode plate group 5 in which a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3 are stacked on top of each other, wherein a separator 4 is arranged between adjacent of the positive and negative electrode plates 2, 3, together with an electrolyte in each cell chamber 6.

[0221] The positive electrode plate 2 comprises a positive electrode grid and a positive electrode active material with which the positive electrode grid is filled, and the negative electrode plate 3 comprises a negative electrode grid and a negative electrode active material with which the negative electrode grid is filled. It should be noted that the positive and negative electrode grids of the present comparative embodiment are made of lead or made from a lead alloy that does not contain antimony (Sb), such as a Pb-Ca alloy, a Pb-Sn alloy or a Pb-Sn-Ca alloy.

[0222] The positive electrode plates 2 are connected in parallel to each other at ear sections 9 of the positive electrode grids by a positive electrode holder 7, and the negative electrode plates 3 are connected in parallel to each other at ear sections 10 of the negative electrode grids by a negative electrode holder 8. The electrode plate groups 5, each housed in the cell chambers 6, are connected in series by a connector 11. The positive electrode holder 7 and the negative electrode holder 8, each housed in the cell chambers 6 located at both ends of the lead-acid battery 1, are each welded to (not shown) poles, and each pole is welded to a corresponding positive and negative electrode terminal 12, 13 arranged on a cover 14.

[0223] In the present comparative embodiment, a surface layer (not shown) consisting of an antimony-containing lead alloy is formed on a surface of the negative electrode grid. The antimony-containing lead alloy reduces hydrogen overpotential, thereby improving the charge acceptance of the lead-acid battery 1. It should be noted that the surface layer preferably consists of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%.

[0224] In the present comparative embodiment, the negative electrode plates 3 are arranged on both sides of the electrode plate group 5 and are each housed in a corresponding pocket-shaped separator 4. This allows the electrolyte to enter the space between the negative electrode plate 3 and the separator 4 in each of the negative electrode plates 3, which are arranged on both sides of the electrode plate group 5, thereby further improving the charge acceptance of the lead-acid battery 1. Even when the lead-acid battery 1 is used for an idle-stop vehicle operating in a short-distance driving mode, this can more effectively reduce the activation of a failsafe mechanism.

[0225] In the present comparative embodiment, the electrolyte contains sodium ions in a range of 0.01 to 0.45 mol / L, and preferably in a range of 0.03 to 0.28 mol / L. The sodium ions contained in the electrolyte have the effect of improving charge recovery after a deep discharge. Even if the lead-acid battery, which has been restored after a deep discharge, is reused in short-distance driving mode, such that a charge / discharge cycle is repeated, the decrease in state of charge (SOC) due to discharge can be reduced, and therefore the activation of the failsafe mechanism can be minimized.

[0226] In the present comparative embodiment, the W / L ratio preferably falls within a range of 0.50 to 0.80, where "L" represents the internal dimension of the cell chamber 6 in the stacking direction of the electrode plate groups 5, and "W" represents the total thickness of the positive and negative electrode plates 2, 3. The W / L value represents the size of the gap between the positive electrode plate 2 and the negative electrode plate 3, i.e., the measure of the amount of electrolyte entering such a gap. When the W / L value falls within a range of 0.50 to 0.80, the charge acceptance of the lead-acid battery 1 is further improved. Even when the lead-acid battery 1 is used for the idle-stop vehicle operating in short-distance driving mode, activation of the failsafe mechanism can thus be more effectively reduced.

[0227] In the present comparative embodiment, a plurality of ribs are preferably formed, at least on inner parts of the separators 4, to create a certain gap between the negative electrode plate 3 and the separator 4. Each rib houses a corresponding negative electrode plate 3, which is arranged on both sides of the electrode plate group 5. This allows the electrolyte to enter the gap formed between the separator 4 and the negative electrode plates 3, which are arranged on each side of the electrode plate group 5, thereby further improving the charge acceptance of the lead-acid battery 1.

[0228] The above advantages can be achieved if the ribs are formed at least on the separators 4, each housing one of the corresponding negative electrode plates 3, which are arranged on both sides of the electrode plate group 5. Of course, however, a plurality of ribs can be formed on the separators 4, each housing one of all the corresponding negative electrode plates 3. If the lead-acid battery 1 contains only a single cell chamber 6, a container of the lead-acid battery 1 can also serve as the cell chamber 6. Third reference example(1) Training of a lead-acid battery

[0229] The lead-acid batteries 1 formed in the present examples are liquid lead-acid batteries with a size of D23L, as specified in JIS D 5301. Seven positive electrode plates 2 and eight negative electrode plates 3 are housed in each cell chamber 6, and each negative electrode plate 3 is housed in a corresponding pocket-shaped separator 4 made of polyethylene.

[0230] Each positive electrode plate 2 was formed in such a way that lead oxide powder is mixed with sulfuric acid and demineralized water to form a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0231] Each negative electrode plate 3 was formed in such a way that an organic additive, etc., is added to the lead oxide powder, the result is mixed with sulfuric acid and demineralized water to produce a paste, and an expanded grid made of a material with the composition of a lead alloy based on calcium is filled with the paste.

[0232] After the formed positive electrode plates 2 and the formed negative electrode plates 3 had matured and dried, the negative electrode plates 3 were each placed in the pocket-shaped separators 4 made of polyethylene, and then the negative electrode plates 3 and the positive electrode plates 2 were stacked alternately on top of each other. As a result, an electrode plate group 5 was formed in which the seven positive electrode plates 2 and the eight negative electrode plates 3 are stacked on top of each other, with the separator 4 positioned between adjacent positive and negative electrode plates 2 and 3. The electrode plate group 5 was placed in each of the six cell chambers 6, and a lead-acid battery 1 was formed in which six cells are connected in series.

[0233] An electrolyte consisting of dilute sulfuric acid with a density of 1.28 g / cm³3 The substance was introduced into the lead-acid battery 1, and subsequently a chemical transformation was carried out in a container. As a result, a lead-acid battery 1 with 12 V and 48 Ah was formed. (2) Evaluation of lead-acid battery characteristics (2-1) Evaluation of the characteristic value in short-distance driving mode

[0234] The trained lead-acid battery 1 underwent repeated charging / discharging cycles designed for short-distance driving mode to evaluate its performance characteristics in this mode. The ambient temperature was 25 °C ± 2 °C. (A) After a discharge over 2.5 hours at 9.6 A, the lead-acid battery is left unattended for 24 hours. (B) A discharge is carried out over 40 seconds at a discharge current of 20 A. (C) Charging is carried out over 60 seconds with a charging voltage of 14.2 V (a limited current of 50 A). (D) After the discharge (B) and charge (C) have been repeated 18 times, a discharge is carried out for 83.5 hours at a discharge current of 20 mA. (E) The cycles are repeated 20 times, with the discharge (B), the charging (C) and the discharge (D) being counted as a single cycle.

[0235] The state of charge (SOC) of the lead-acid battery after 20 cycles was measured, and such a value was considered as a characteristic value in the short-distance driving mode. (2-2) Charge recovery after deep discharge

[0236] For the trained lead-acid battery 1, an evaluation of the charge recovery after a repeated charge / discharge cycle was carried out using the following procedure, assuming that the lead-acid battery 1, which has been restored after a deep discharge, is reused in the short-distance driving mode. (A) A discharge is carried out at a current with a five-hour rate (a discharge current of 9.8 A) down to 10.5 V. (B) Subsequently, a discharge is carried out under a load of 10 W for 14 days at a temperature of 40 °C ± 2°C, and then the lead-acid battery is left unattended with the circuit interrupted for 14 days. (C) Subsequently, charging is carried out for four hours at a temperature of 25 °C ± 3 °C with a charging voltage of 15.0 V (a limited current of 25 A). (D) The lead-acid battery is then left unattended for 16 hours or longer in an atmosphere of -15 °C ± 1 °C, and then discharged at 300 A to 6.0 V.

[0237] The time it takes for the lead-acid battery voltage to reach 6.0 V was evaluated as charge recovery after a deep discharge. (Reference example 5-1)

[0238] Accumulators E1 to E7 were constructed, each consisting of a surface layer made of an antimony-containing lead alloy on the surface of a negative electrode grid. Sodium sulfate (Na₂SO₄) was added to an electrolyte such that the Na₂ ion concentration fell within the range of 0.005 to 0.56 mol / L. The performance of each accumulator in short-distance driving mode and the charge recovery of each accumulator after deep discharge were evaluated. It should be noted that the negative electrode plates were arranged on both sides in an electrode plate group and each was housed in a corresponding pocket-shaped separator.

[0239] The negative electrode grid is formed from an expanded metal lattice of Pb-1.2Sn-0.1Ca, and the surface layer is made from a Pb-3Ma%Sb foil. In addition, a positive electrode grid is formed from an expanded metal lattice of Pb-1.6Sn-0.1Ca, and no surface layer is formed on the positive electrode grid.

[0240] Table 11 presents the evaluation results for each characteristic value. It should be noted that an accumulator E8, in which no surface layer is formed on any surface of a negative electrode grid, and an accumulator E9, in which negative electrode grids are not each housed in pocket-shaped separators, but in which positive electrode grids are each housed in the pocket-shaped separators, were used as reference samples. [Table 11] Na ion content (mol / L) Negative electrode plate separator Key figure in short-distance driving mode SOC (%) Recovery after deep discharge Duration (minutes) Negative electrode grid surface layer form Element to be accommodated Accumulator E1 0,005 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 73 1,5 AccumulatorE2 0,01 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 73 2,5 AccumulatorE3 0,03 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 74 2,9 AccumulatorE4 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 75 3,0 Accumulator E5 0,28 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 74 3,0 Accumulator E6 0,45 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 70 3,0 Accumulator E7 0,56 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 59 2,9 Accumulator E8 0,11 Pb-Sn-Ca not trained Bag negative electrode plate 57 2,9 Accumulator E9 0,11 Pb-Sn-Ca Pb-Sb Bag positive electrode plate 56 2,5

[0241] As can be seen from Table 11, batteries E2 to E6, whose sodium ion content in the electrolyte ranges from 0.01 to 0.45 mol / L, exhibit that the state of charge (SOC), which indicates the characteristic value in short-distance driving mode, is equal to or greater than 70%, and that the recovery time after a deep discharge is 2.9 minutes or longer. For lead-acid batteries exhibiting such values, a sufficient lifetime characteristic value can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling stop vehicle is used in short-distance driving mode.Even if the idle stop vehicle is reused in short-distance driving mode after the lead-acid battery has temporarily been in a deep discharge state, a decrease in SOC due to discharge can be further reduced, and therefore activation of the failsafe mechanism can be reduced.

[0242] In particular, the E3 to E5 batteries, whose sodium ion content in the electrolyte ranges from 0.03 to 0.28 mol / L, exhibit excellent characteristics, as the state of charge (SOC), which indicates the characteristic value in short-distance driving mode, is equal to or greater than 74%, and the recovery time after a deep discharge is 3.0 minutes or longer. These batteries demonstrate superior performance when the vehicle is used in short-distance driving mode.

[0243] In contrast, the E7 battery, whose sodium ion concentration in the electrolyte is 0.56 mol / L, shows a low state of charge (SOC) of 59%, which indicates the characteristic value in short-distance driving mode. This may be because the sodium ions in the electrolyte block a charging reaction.

[0244] The E1 battery, whose sodium ion concentration in the electrolyte is 0.005 mol / L, shows a low recovery time of 1.5 minutes after deep discharge. This may be due to a reduced recovery rate after deep discharge.

[0245] The E8 battery, in which no surface layer is formed on the negative electrode grid, shows that the state of charge (SOC), which indicates the characteristic value in short-distance driving mode, has an extremely low value of 57%. This may be due to the absence of a lead alloy foil containing Sb on the surface of the negative electrode grid, thus preventing a decrease in hydrogen overpotential and resulting in low charge acceptance.

[0246] The E9 battery, in which each positive electrode plate is housed in a corresponding pocket-shaped separator, shows a low state of charge (SOC) of 56%, which indicates the characteristic value in short-distance driving mode. This can be due to the following reasons: Because the negative electrode plates, located on either side of the electrode plate assembly, are not each housed in their respective pocket-shaped separators, they are pressed against the inner walls of the cell chamber. Consequently, the charge acceptance is reduced due to a lack of electrolyte entering the space on the side near the inner wall of the cell chamber relative to the negative electrode plate.

[0247] Based on the above results, a lead-acid battery exhibiting excellent charge recovery after deep discharge, reducing the activation of a failsafe mechanism, and adaptable for an idle-stop vehicle used in a short-distance driving mode, can be achieved by forming a surface layer consisting of an antimony-containing lead alloy on the surface of a negative electrode grid that does not contain antimony, by arranging negative electrode plates, each housed in a corresponding pocket-shaped separator, on both sides of an electrode plate group, and by providing an electrolyte containing sodium ions in a range of 0.01 to 0.45 mol / L and preferably in a range of 0.03 to 0.28 mol / L. (Reference example 5-2)

[0248] To further improve charge acceptance, accumulators E10 to E16 were designed from accumulator E4 as described in Example 5-1 such that the W / L ratio varies between 0.45 and 0.85, where "L" represents the internal dimension of the cell chamber in the stacking direction of the electrode plate groups and "W" represents the total thickness of the positive and negative electrode plates. The performance of each accumulator in short-distance driving mode and the recovery of each accumulator after deep discharge were evaluated. Accumulator E13 is identical to accumulator E4 as described in Example 5-1.

[0249] Fig.Figure 3 is the cross-sectional view of cell chamber 6. The internal dimension of cell chamber 6 in the stacking direction of the electrode plate groups, each housed in cell chamber 6, is represented by “L”, the thickness of the positive electrode plate 2 is represented by “W1”, the thickness of the negative electrode plate 3 is represented by “W2”, and the total thickness (W1 x 7 + W2 x 8) of the positive electrode plates 2 and the negative electrode plates 3 is represented by “W”.

[0250] Table 12 presents the evaluation results for each indicator. [Table 12] Na ion content (mol / L) Negative electrode grid separator Thickness ratio of the electrode plates to the cell chamber W / L Key figure in short-distance driving mode: SOC (%) Recovery after deep discharge Duration (minutes) Lattice composition Film composition form Element to be accommodated E10 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,45 67 2,7 E11 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,50 71 2,8 E12 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,60 74 2,8 E13 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,65 75 3,0 E14 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,70 74 3,0 E15 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,80 71 2,7 E16 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate 0,85 66 2,5

[0251] As can be seen from Table 12, batteries E11 to E15, whose W / L ratio falls within the range of 0.50 to 0.80, show that the SOC, which indicates the characteristic value in the short-distance driving mode, is equal to or greater than 71%. For lead-acid batteries exhibiting such values, a sufficient lifetime characteristic value can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling-stop vehicle is used in the short-distance driving mode. Specifically, batteries E12 to E14, whose W / L ratio falls within the range of 0.60 to 0.70, show that the SOC, which indicates the characteristic value in the short-distance driving mode, is equal to or greater than 74%. These batteries exhibit preferential performance when the idling-stop vehicle is used in the short-distance driving mode.

[0252] In contrast, the E10 battery, with a W / L ratio of 0.45, shows a low state of charge (SOC) of 67%, which indicates the characteristic value in short-distance driving mode. This may be due to reduced charge acceptance resulting from a lack of active material.

[0253] The E16 battery, with a W / L ratio of 0.85, shows a low state of charge (SOC) of 66%, which indicates the characteristic value in short-distance driving mode. This may be due to reduced charge acceptance resulting from a lack of electrolyte entering the spaces between adjacent cells in the E16 battery.

[0254] Of the E10 to E16 batteries, all show a high recovery time after deep discharge, at or above 2.5 minutes. This may be due to the presence of sodium ions in the electrolyte at a concentration of 0.11 mol / L, which appears to improve charge recovery after deep discharge.

[0255] Based on the above results, the charge acceptance can be further improved so that the W / L ratio is set in the range of 0.50 to 0.80, and preferably in the range of 0.60 to 0.70. Even when the lead-acid battery is used for the idle-stop vehicle operating in short-distance driving mode, this can more effectively reduce the activation of the failsafe mechanism. (Reference example 5-3)

[0256] To further improve charge uptake, an accumulator E17 was next formed from the accumulator E4 formed in Example 5-1 such that a plurality of ribs 15 were formed on an inner part of the separator 4 to create a certain gap between a negative electrode plate 3 and a pocket-shaped separator 4 in which the negative electrode plate 3 is housed, as shown in Fig.Figure 3 illustrates this. It should be noted that an accumulator E18, in which ribs 15 are configured to face positive electrode plates 2, an accumulator E19, in which each positive electrode plate 2 is housed in a corresponding pocket-shaped separator 4 and ribs 15 are configured to face negative electrode plates 3, and an accumulator E20, in which plate-shaped separators are used instead of pocket-shaped separators 4 and ribs 15 are configured to face the negative electrode plates 3, were designed as comparative examples. The height of the rib 15 was 0.2 mm, and it was formed integrally with the separator 4.

[0257] Table 13 presents the evaluation results for each indicator. [Table 13] Na ion content (mol / L) Negative electrode grid separator Key figure in short-distance driving mode: SOC (%) Recovery after deep discharge Duration (minutes) Lattice composition Film composition form Element to be accommodated rib E17 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate negative electrode side 75 3,0 E18 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag negative electrode plate Positive electrode side 63 3,0 E19 accumulator 0,11 Pb-Sn-Ca Pb-Sb Bag positive electrode plate negative electrode side 54 2,5 E20 accumulator 0,11 Pb-Sn-Ca Pb-Sb plate - negative electrode side 57 2,7

[0258] As can be seen from Table 13, the E17 battery, in which the ribs on the inner part of each separator are designed to face the negative electrode plates, exhibits a state of charge (SOC) of 75%, which indicates the characteristic value in short-distance driving mode. With such values, a sufficient lifetime characteristic can be maintained, and activation of the failsafe mechanism can be reduced, even when the idling-stop vehicle is used in short-distance driving mode.

[0259] In contrast, of the battery E18, in which the ribs are configured to face the positive electrode plates, the battery E19, in which each positive electrode plate is housed in a corresponding pocket-shaped separator and the ribs are configured to face the negative electrode plates, and the battery E20, in which plate-shaped separators are used and the ribs are configured to face the negative electrode plates, each shows that the SOC, which indicates the characteristic value in the short-distance driving mode, has a low value of 63% or less. This can be due to the following reasons.When the negative electrode plates, each arranged on both sides in the electrode plate group, are pressed against the inner walls of the cell chamber, no gap has been formed between the negative electrode plate and the cell chamber, and the charge uptake is reduced due to a lack of electrolyte entering such a gap.

[0260] Of the E17 to E20 batteries, all show a high recovery time after deep discharge, equal to or greater than 2.5 minutes. This may be due to the presence of sodium ions in the electrolyte at a concentration of 0.11 mol / L, which appears to improve charge recovery after deep discharge.

[0261] Based on the above results, the charge acceptance of the lead-acid battery can be further improved by housing each negative electrode plate in a corresponding pocket-shaped separator and by forming ribs on the inner part of the separator to create a certain gap between the negative electrode plate and the separator. Even when the lead-acid battery is used in an idle-stop vehicle operating in short-distance driving mode, this can more effectively reduce the activation of the failsafe mechanism. Commercial applicability

[0262] The present invention is advantageous for lead-acid batteries used in idle-stop vehicles. Description of the reference symbols 1 lead-acid battery 2 Positive electrode plate 3 Negative electrode plate 4 Separator 5 Electrode plate group 6-cell chamber 7 Positive electrode holder 8 Negative electrode holder 9, 10 ear part 11 connectors 12 Positive electrode connection 13 Negative electrode connection 14 Cover 15th rib

Claims

[1] Lead-acid battery in which at least one electrode plate group, configured such that a plurality of positive electrode plates and a plurality of negative electrode plates are stacked on top of each other, wherein a separator is arranged between adjacent positive and negative electrode plates, is housed together with an electrolyte in at least one cell chamber, where each positive electrode plate includes a positive electrode grid made of lead or a lead alloy that does not contain antimony, a positive electrode surface layer formed on a surface of the positive electrode grid and consisting of an antimony-containing lead alloy, and a positive electrode active material with which the positive electrode grid is filled and which includes lead oxide, Each negative electrode plate contains a negative electrode grid made of lead or a lead alloy that does not contain antimony, a negative electrode surface layer formed on a surface of the negative electrode grid and consisting of an antimony-containing lead alloy, and a negative electrode active material with which the negative electrode grid is filled and which includes lead oxide, NS / PS falls into a range of 0.3 to 0.8, where PS represents an area of ​​the positive electrode surface layer on the surface of the positive electrode grid and NS represents an area of ​​the negative electrode surface layer on the surface of the negative electrode grid, and The positive and negative electrode surface layers consist of a Pb-Sb-based alloy containing antimony at a content of 1.0 to 5.0 wt%. [2] Lead-acid battery according to claim 1, wherein the antimony content in the negative electrode surface layer is higher than in the positive electrode surface layer. [3] Lead-acid battery according to claim 1, wherein strands of the positive electrode grid have no twisting and at least one strand of the negative electrode grid has twisting.

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