JPWO2013046499A1 - Lead-acid battery for energy storage - Google Patents

Abstract

The lead acid battery for energy storage includes an electrode plate group and an electrolyte impregnated in the electrode plate group, and the electrode plate group includes a plurality of negative electrodes, a plurality of positive electrodes, and a plurality of separators. Comprises a negative electrode lattice and a negative electrode active material held in the negative electrode lattice, the positive electrode comprises a positive electrode lattice and a positive electrode active material held in the positive electrode lattice, and the separator comprises the positive electrode and the negative electrode Is separated. The positive electrode active material has a total pore volume of 0.087 to 0.120 cm 3 / g, and the negative electrode active material contains 3.2 to 4.8% by mass of barium sulfate.

Description

  The present invention relates to a lead storage battery for energy storage. More specifically, the present invention relates to an energy storage lead-acid battery having excellent discharge capacity and charge acceptance at low temperatures.

  The valve-controlled lead-acid battery has advantages such as low cost, stable output, and maintenance-free, and has been widely used in the fields of vehicle start-up, standby power supply, energy storage system, and the like. Lead storage batteries used in energy storage systems (simply called “lead storage batteries for energy storage”) convert renewable energy in the natural world, such as solar energy and wind energy, into direct current electricity, and then adjust the power to external devices. Can be output.

  Lead storage batteries for energy storage need to operate in a natural environment for a long period of time, so they need to have good cycle life characteristics as well as excellent discharge capacity and charge acceptance at low temperatures. It is required that In addition, since lead storage batteries for energy storage usually operate at a low discharge rate, it is necessary to achieve desired battery performance under conditions of a low discharge rate by appropriately designing an electrode plate.

As for the positive electrode of the lead storage battery, the conductivity of lead dioxide (PbO ₂ ) as a positive electrode active material is relatively inferior, so that there is a problem that discharge at low temperatures is difficult. In addition, the positive electrode active material becomes a porous body after chemical conversion, and its pore structure also has a great influence on the discharge characteristics of the lead-acid battery. The main cause of this is that lead sulfate, which is poorly soluble in the positive electrode active material during the discharge process. This is because the generation of crystals closes the pores for supplying the electrolytic solution, making it difficult for the discharge reaction to continue.

  In the porous body of the positive electrode active material, it is known that the smaller the pore diameter, the more difficult the diffusion of sulfate ions contributing to the electrode reaction, leading to deterioration of the high rate discharge characteristics. Therefore, in order to improve the discharge performance of the positive electrode of the lead-acid battery, the ratio of the total pore volume of the positive electrode active material, in particular the volume of pores having a large pore diameter, is increased, thereby making it easier for the electrolyte to diffuse and the positive electrode A method of increasing the utilization rate of the active material is performed. For example, Patent Document 1 discloses that the total pore volume of the positive electrode active material falls within the range of 0.14 to 0.18 cc / g, thereby improving the discharge capacity of the lead-acid battery during high-rate discharge. ing. Further, in order to achieve a higher capacity of the battery, Patent Document 2 proposes a method in which the volume of pores having a pore diameter of 1 μm or more in the positive electrode is set to 50% or more of the total pore volume. However, both of these documents are inventions related to increasing the capacity of lead-acid batteries under normal temperature and high-rate discharge conditions, and the discharge characteristics of lead-acid batteries under low-temperature and low-rate discharge conditions have not been studied.

About the negative electrode of a lead acid battery, since the lead sulfate as a negative electrode active material tends to solidify, there exists a tendency for the charge acceptance property under low temperature to fall easily. Currently, a method of adding an additive to the negative electrode is mainly employed so as to improve the low-temperature charge acceptability of the battery. For example, Patent Document 3 describes that 2 to 5% by mass of barium sulfate (BaSO ₄ ) is added to the negative electrode active material with respect to the lead powder. And it is described that barium sulfate makes it easy to make the discharge product, that is, lead sulfate, fine as a nucleating agent, thereby improving the charge acceptability of the battery at a low temperature.

However, in a low-temperature environment, even if a negative electrode using a negative electrode active material to which BaSO ₄ is added is used to produce a lead-acid battery, the charge acceptability can be improved to some extent, It is difficult to extract the quantity as a discharge capacity. This is because, in a high state of charge (SOC), the concentration of sulfuric acid as the electrolytic solution is high, and the viscosity of the electrolytic solution is high at low temperatures, so that the ion diffusion resistance is increased, and thus the discharge characteristics are greatly affected. It is for receiving.

  Thus, so far, the discharge capacity and charge acceptance of energy storage lead-acid batteries used in low temperature environments are still low, and desirable battery characteristics cannot be obtained.

Japanese Patent Laid-Open No. 11-73950 JP-A-6-140030 JP 2003-51307 A

  In view of the above problems, an object of the present invention is to provide a lead acid battery for energy storage having excellent discharge capacity and charge acceptance at low temperatures.

As a result of studying the discharge characteristics of the lead-acid battery at low temperatures, the inventors of the present application have found that the increase in the total pore volume of the positive electrode active material or the increase in the BaSO ₄ content in the negative electrode active material does not increase the It was discovered that the discharge capacity cannot be improved. Furthermore, the total pore volume of the positive electrode active material is appropriately reduced and within an appropriate range, and by adding a specific additive to the negative electrode active material, not only has good cycle life characteristics, It was discovered that an energy storage lead-acid battery having excellent discharge capacity and charge acceptance at low temperatures could be provided, and the present invention was completed.

  Although the cause of the above phenomenon is not yet clear, it can be assumed that the viscosity of the electrolytic solution increases at low temperatures, and only the pores having a specific pore diameter play a decisive role for the diffusion of the electrolytic solution. Therefore, the charge / discharge characteristics of the positive electrode can be improved by keeping the total pore volume of the positive electrode active material within an appropriate range. Moreover, by adding a nucleating agent and / or other additives to the negative electrode active material, the charge / discharge characteristics of the negative electrode are improved, and the charge / discharge characteristics between the positive and negative electrodes are balanced, thereby charging and discharging characteristics of the entire battery. In addition, cycle life characteristics can be improved.

Specifically, a lead storage battery for energy storage according to the present invention includes an electrode plate group and an electrolytic solution impregnated in the electrode plate group, and the electrode plate group includes a plurality of negative electrodes, a plurality of positive electrodes, and a plurality of positive electrodes. The negative electrode includes a negative electrode lattice and a negative electrode active material held in the negative electrode lattice, the positive electrode includes a positive electrode lattice and a positive electrode active material held in the positive electrode lattice, The separator is an energy storage lead-acid battery that separates the positive electrode and the negative electrode, and the total pore volume of the positive electrode active material is 0.087 to 0.120 cm ³ / g. Is characterized by containing 3.2 to 4.8% by weight of barium sulfate.

  The positive electrode active material preferably has a large number of pores having a pore diameter of 0.8 μm.

  Moreover, it is preferable that 0.3-2.0 mass% acetylene black is contained in the said negative electrode active material.

  The negative electrode active material preferably further contains 0.1 to 2.0% by mass of a lignin surfactant.

  The weight ratio of the negative electrode active material to the positive electrode active material, that is, the negative electrode active material / positive electrode active material is preferably 0.7 to 0.95.

  It is preferable that an expanded lattice is used at least for the positive electrode lattice.

  The separator includes a bag-shaped separator made of synthetic fiber subjected to a hydrophilic treatment and a chip-shaped separator made of glass fiber, the bag-shaped separator contains the positive electrode, and the chip-shaped separator is It is preferable to be sandwiched between a bag-shaped separator and the negative electrode. Among them, the synthetic fiber includes at least acrylonitrile-based fine fibers having a diameter of 0.5 μm to 2.0 μm, and further includes acrylonitrile-based thick fibers having a diameter of 2.5 μm to 8.0 μm. More preferably, the content of the acrylonitrile-based fine fibers is greater than the content of the acrylonitrile-based thick fibers.

  ADVANTAGE OF THE INVENTION According to this invention, the lead storage battery for energy storage which not only has a favorable cycle life characteristic but can obtain the outstanding discharge capacity and charge acceptance property also at low temperature can be provided.

It is a perspective view which shows typically the structure of the lead acid battery of this invention. It is a graph which shows the relationship between the discharge capacity and discharge rate of the lead storage battery of this invention under different ambient temperature, (a) is when ambient temperature is 25 degreeC, (b) is when ambient temperature is -15 degreeC Indicates. It is a graph of the differential curve which shows the pore distribution of the positive electrode active material of this invention. It is a graph of the integral curve which shows the pore distribution of the positive electrode active material of this invention. It is a graph of the differential curve which shows the pore distribution of the negative electrode active material of this invention.

  Various characteristics are required for lead-acid batteries used in various applications. Therefore, it is necessary to make various different designs for the lead-acid battery in order to optimize the required characteristics. The lead acid battery for energy storage of the present invention is mainly used for a storage system of natural energy such as solar energy. Generally, the use environment of these lead acid batteries for energy storage is low to normal temperature. For example, it is -15-40 degreeC and can reach -30-50 degreeC in an extreme case. Therefore, the lead acid battery for energy storage of this invention needs to endure long-term use under low temperature. Moreover, the discharge rate which the lead storage battery for energy storage requires is low.

  Based on the above characteristics of the lead storage battery for energy storage, the inventors of the present application mainly examined how to improve the charge / discharge characteristics and cycle life of the lead storage battery at low temperatures and low discharge rates. In this specification, low temperature refers to a temperature range of −30 ° C. to 0 ° C., and low discharge rate refers to a range of 0.01 C to 1.0 C.

  Hereinafter, the present invention will be described in detail while being associated with each component of the energy storage lead-acid battery.

(Positive electrode)
The positive electrode includes a positive electrode grid having ears and a positive electrode active material held by the positive electrode grid. As the positive electrode grid, either an expanded grid or a cast grid often used in lead-acid batteries may be used. From the viewpoint of increasing the capacity of the positive electrode, it is preferable to use an expanded grid for the positive electrode.

  A known lead powder can be used as the main raw material of the positive electrode active material, and a small amount of other additives such as a conductive material and a binder may be included in addition to the lead powder. The method for producing the positive electrode active material is as follows. That is, after the raw material lead powder (main components are lead and lead monoxide) is kneaded with dilute sulfuric acid, the formed paste is applied to the positive electrode lattice, and after drying, a chemical conversion treatment is performed to obtain a porous body. The chemical conversion treatment may be any one of electrode plate chemical conversion and battery case chemical conversion.

  The positive electrode active material is formed into a porous body through chemical conversion. The pore structure of the porous body affects the diffusion of the electrolytic solution. In general, the performance of a battery is lowered at a low temperature, and in particular, the discharge performance of the positive electrode is lowered. This is because in a lead-acid battery at a low temperature, the viscosity of sulfuric acid as the electrolyte is increased, and the ion diffusion resistance is increased. Therefore, in order to solve the above problem, it is necessary to improve the pore structure of the positive electrode active material to facilitate the diffusion of the electrolyte and to facilitate the discharge reaction.

<Porosity distribution of positive electrode active material>
In the present invention, the pore structure of the positive electrode active material is represented by measuring the pore distribution of the positive electrode active material. By the mercury intrusion method, the graph of the differential curve of the pore distribution of the positive electrode active material shown in FIG. 3 (that is, the differential curve indicating the distribution of the pore volume according to the pore size) is obtained. Represents a rate. Further, by performing an integral operation on the differential curve, the graph of the integral curve shown in FIG. 4 is obtained. From the graph of the integral curve, the total pore volume of the positive electrode active material and the specific pore diameter range are obtained. The pore volume can be determined.

  The term “pore volume” here is different from the commonly used “porosity”. Porosity represents only the ratio of the sum of the volumes of all pores in the porous body to the total volume of the porous body, but the pore volume includes the meanings of total pore volume, pore size distribution, average pore size, etc. ing. The “total pore volume of the positive electrode active material” refers to the total volume of all the pores present in the porous body of the positive electrode active material. In this specification, the “total pore volume of the positive electrode active material” Is sometimes simply referred to as “positive electrode pore volume”.

  Various methods for adjusting the pore distribution of the active material are known. For example, in the manufacturing process of the positive electrode active material, the pore structure of the positive electrode active material is controlled by a method such as controlling the particle size of the lead powder of the raw material, changing the concentration or capacity of sulfuric acid, or changing the dropping rate of sulfuric acid. Can be adjusted. In the present invention, the total pore volume of the positive electrode active material tends to decrease as the amount of water or sulfuric acid during the kneading of the positive electrode active material paste is reduced or the density of the paste is increased.

(Negative electrode)
The negative electrode includes a negative electrode lattice having ears and a negative electrode active material held by the negative electrode lattice. As the negative electrode grid, any one of an expanded grid and a cast grid normally used in lead-acid batteries can be used. The negative electrode active material mainly contains metallic lead and lead sulfate, and further contains various additives for improving battery performance or a binder for increasing the adhesion between the respective materials.

  Hereinafter, various additives in the negative electrode active material will be described. In this specification, the content of each additive is calculated based on the total weight of the negative electrode active material.

<Nucleating agent>
Since lead sulfate in the negative electrode active material is easily solidified during charging, there is a problem that charge acceptability at low temperatures is low. By adding a nucleating agent to the negative electrode active material, lead sulfate can be made finer, thereby improving the charge acceptability of the negative electrode.

Examples of the nucleating agent include barium sulfate (BaSO ₄ ) and strontium sulfate (SrSO ₄ ). There is an appropriate range for the content of the nucleating agent in the negative electrode active material. If the content of the nucleating agent is too large, the amount of the negative electrode active material is relatively decreased, and the structure becomes too dense, so that the charge acceptability at low temperature is deteriorated, and the discharge capacity of the battery is also small. turn into. On the other hand, when the content of the nucleating agent is too small, the role as the nucleating agent cannot be fully exhibited, and the lump of the solidified negative electrode active material becomes large, so that the charge acceptability is also lowered. In the present invention, the nucleating agent is an essential component in the negative electrode active material, and it is preferable to add 3.2 to 4.8% by mass of the nucleating agent with respect to the negative electrode active material.

<Conductive material>
A conductive material may be added to the negative electrode active material. Commonly used conductive materials include acetylene black, carbon black, and graphite. In the present invention, the conductive material is not an essential component in the negative electrode active material, but if a conductive material is added, the conductive performance of the negative electrode can be further improved.

  The conductive material content in the negative electrode active material is preferably 0.3 to 2.0% by mass. When there is too little content of an electroconductive material, the electroconductivity of a negative electrode will worsen and charge / discharge performance will worsen. On the other hand, when there is too much content of a conductive material, there exists a problem that it is difficult to produce.

<Expansion agent>
Moreover, you may add a swelling agent further with respect to a negative electrode active material. Examples of commonly used swelling agents include lignin surfactants (hereinafter simply referred to as lignin) and humic acid. The lignin mainly includes lignin sulfonate having an amphiphilic ionic surfactant structure such as sodium lignin sulfonate and calcium lignin sulfonate. In the present invention, the expansion agent is not an essential component in the negative electrode active material, but by adding the expansion agent to the negative electrode active material, the negative electrode active material can be prevented from contracting and the cycle life of the battery can be further improved. .

  The expansion agent content in the negative electrode active material can employ a range of a normal content in this field, and is not particularly limited. For example, the content can be set to 0 to 5% by mass. If it is 0.0 mass%, it is preferable, and if it is 0.2-0.5 mass%, it is more preferable.

(Separator)
The separator used in the lead storage battery for energy storage of the present invention employs a chip-like separator made of glass fiber, and constitutes an electrode plate group by laminating the chip-like separator between a positive electrode and a negative electrode. It is also possible to adopt a bag-shaped separator made of a synthetic fiber nonwoven fabric subjected to a hydrophilic treatment, and to form a plate group by putting the positive electrode or the negative electrode in the bag-shaped separator and then overlapping the negative electrode or the positive electrode. Good. Moreover, you may use combining said bag-shaped separator and chip-shaped separator.

  From the standpoint of enhancing battery safety and preventing internal short circuits, the positive electrode is housed in a bag-shaped separator made of a synthetic fiber nonwoven fabric that has been subjected to a hydrophilic treatment, and the chip-shaped separator made of glass fiber is replaced with a bag-shaped separator and a negative electrode Is preferably sandwiched between the two.

  From the viewpoint of enhancing hydrophilicity, the synthetic fiber is preferably an acrylonitrile fiber, and the synthetic fiber contains at least acrylonitrile fiber having a diameter of 0.5 μm to 2.0 μm. The acrylonitrile-based fine fiber has an appropriate fineness, a number of wrinkles on the surface thereof, and a certain structural strength. The acrylonitrile fiber nonwoven fabric separator of the present invention uses the above acrylonitrile fiber having a diameter of 0.5 μm to 2.0 μm, so that hydrophilicity is improved and the electrolyte is firmly held. Therefore, the life characteristics of the battery can be set to a level equivalent to or higher than that of a conventional battery using a polyolefin fiber nonwoven fabric separator subjected to a hydrophilic treatment. The diameter of the acrylonitrile-based fine fiber is preferably 0.8 μm to 1.6 μm from the viewpoint of realizing such an effect better.

  In addition to the above acrylonitrile fine fibers having a diameter of 0.5 μm to 2.0 μm, acrylonitrile thick fibers having a diameter of 2.5 μm or more may be further used. By doing so, the structural strength of the separator is further improved, and the separator is less likely to be crushed, so that the life characteristics of the battery can be further improved. However, since the specific surface area of the acrylonitrile-based thick fibers is smaller than that of the acrylonitrile-based fine fibers, the surface wrinkles are relatively small. Therefore, if the acrylonitrile-based thick fiber is too thick, the specific surface area becomes small, wrinkles on the surface of the thick fiber also decrease, and it becomes difficult to hold and store the electrolyte solution, which adversely affects the performance of the separator. As a result, the life characteristics of the battery are affected. Therefore, from this point, the diameter of the acrylonitrile-based thick fiber is preferably 2.5 μm to 8.0 μm, and more preferably 2.5 μm to 7.5 μm.

  Considering comprehensively from the three points of hydrophilicity of acrylonitrile fiber, separator structural strength and battery life characteristics, the content of acrylonitrile fiber in the nonwoven fabric separator of acrylonitrile fiber of the present invention is acrylonitrile fiber. It is preferable that there is more content than.

  Considering the hydrophilicity of the acrylonitrile fiber and the battery life characteristics, the content of the acrylonitrile fiber in the nonwoven fabric separator of the acrylonitrile fiber is preferably 50% by mass to 100% by mass. In view of the structural strength of the separator and the life characteristics of the battery, in the acrylonitrile fiber nonwoven fabric separator, the content of the acrylonitrile fiber is preferably more than 0% by mass and 50% by mass or less.

  In the nonwoven fabric separator of acrylonitrile fiber of the present invention, a polyolefin fiber such as a polypropylene fiber having a known diameter of 2.0 μm to 5.0 μm may be used in place of the acrylonitrile thick fiber. Even in this case, the performance of the obtained separator is good, but when the polyolefin fiber is a low hydrophilic fiber such as a polypropylene fiber that has not been hydrophilized, the polypropylene in the nonwoven fabric separator of acrylonitrile fiber is used. The fiber should not exceed 25% by weight, otherwise the separator performance will be degraded.

(Lead battery)
FIG. 1 is a perspective view schematically showing the structure of the lead storage battery of the present invention. The lead storage battery 1 includes a battery case 2 and an electrode plate group 3 accommodated in the battery case 2. The electrode plate group 3 is formed by laminating a plurality of positive electrodes 4 and a plurality of negative electrodes 5 with a separator 6 interposed therebetween. In the present embodiment, the negative electrode 5 is located outside the electrode plate group 3, and the number thereof is one more than that of the positive electrode 4. The positive electrode 4 is accommodated in a bag-shaped separator 6 a, and a chip-shaped separator 6 b is sandwiched between the bag-shaped separator 6 a and the negative electrode 5.

  One end of the positive electrode connection member 7 is connected to the plurality of positive electrodes 4, and the other end is connected to a positive electrode terminal (not shown) provided on the battery cap. One end of the negative electrode connection member 8 is connected to the plurality of negative electrodes 5, and the other end is connected to a negative electrode terminal (not shown) provided on the battery cap. A battery cap (not shown) is attached to the opening of the battery case 2. A vent valve is provided at a liquid inlet provided in the battery cap, and this vent valve is used to discharge gas generated inside the battery to the outside of the battery.

  In order to clarify the relationship between the positive electrode pore structure and the additive in the negative electrode active material, and the charge / discharge characteristics of the lead storage battery at low temperatures, the inventors of the present application produced several types of test lead storage batteries, The following series of experiments were conducted at various temperature conditions and discharge rates.

Specifically, the inventors of the present application produced three types of positive electrodes A, B, and C by changing the amount of acid used during the kneading of the positive electrode active material. The pore distribution was measured by the mercury intrusion method. Of these, the positive electrode C is a commonly used positive electrode and has a relatively large total pore volume (0.122 cm ³ / g). Since the positive electrodes B and A are sequentially reduced in the amount of acid during kneading, the numerical value of the total pore volume obtained is also decreasing in order, the pore volume of the positive electrode B is 0.110 cm ³ / g, The pore volume is 0.085 cm ³ / g. In addition, the inventors of the present application prototyped several different types of negative electrodes by adding barium sulfate, lignin, and acetylene black at different contents to the negative electrode active material.

  Batteries # 1 to # 8 were produced by combining the produced positive electrode C and positive electrode B with different negative electrodes. Table 1 shows specific parameters of the positive electrode and the negative electrode used in these batteries. These batteries were subjected to discharge tests at different discharge rates under ambient temperatures of 25 ° C. and −15 ° C., respectively, and graphs shown in FIGS. 2A to 2B were created based on the test results.

  From Table 1, it can be seen that the difference between the battery # 1 and the battery # 2 is only that the pore volume of the positive electrode is different. However, looking at the results of FIG. 2, the increase in the pore volume of the positive electrode has no obvious improvement effect on the discharge capacity of the battery, both at low temperatures and at room temperature.

On the other hand, comparing the battery # 2 and the batteries # ^{3 to} # 5, in which the pore volume of the positive electrode is both 0.110 cm ³ / g, even when only the additive content in the negative electrode active material is changed, The battery's discharge capacity is not clearly improved. Further, when comparing the battery # 6 and the battery # 1 in which the pore volume of the positive electrode is both 0.122 cm ³ / g, the discharge is performed even when only the barium sulfate content in the negative electrode active material is increased. Capacity has hardly improved.

However, when battery # 1 and battery # 5 are compared, a relatively small pore volume (0.110 cm ³ / g) is adopted for the positive electrode of battery # 5, while the negative electrode active material contains barium sulfate. When the amount was increased (4.2% by mass), a clear improvement effect was observed in the discharge capacity of Battery # 5 at a low temperature (−15 ° C.). This reveals that a specific combination of the positive electrode pore volume and the barium sulfate content in the negative electrode active material has a synergistic effect on improving the discharge capacity of the battery at low temperatures and low discharge rates. Yes.

  Further, as shown in batteries # 7 and # 8, by appropriately increasing the acetylene black content in the negative electrode active material, the battery discharge capacity at low temperature and low discharge rate was dramatically improved. In addition, this effect was more remarkable at a low discharge rate (0.01 to 1.0 C).

  In addition, when the expanded lattice was used for both positive and negative electrodes in Battery # 8, the effect of improving the discharge capacity became even more remarkable.

  The inventors of the present application further investigated the above phenomenon and obtained the following knowledge.

  As shown in FIGS. 2A and 2B, the discharge capacity decreases as the temperature decreases, and the discharge capacity tends to increase as the discharge rate decreases. This indicates that the ion diffusion of the electrolyte is affected by factors such as temperature and discharge rate, which affects the discharge performance of the battery.

When the content of barium sulfate in the negative electrode active material is the same, the pore volume of the positive electrode is relatively large (0.122 cm ³ / g), and the pore volume of the battery # 1 and the positive electrode is relatively small (0.110 cm ³ / G) When compared with the battery # 2, the battery # 1 was superior in discharge capacity at room temperature (25 ° C.). This is because the electrolyte viscosity is low at room temperature, and the amount of electrolyte affects the battery discharge capacity. The larger the positive electrode pore volume, the greater the amount of electrolyte flowing to the positive electrode. It shows that it is more advantageous to improve performance. However, as the temperature decreases, as shown in FIG. 2B, the discharge capacities of the battery # 2 and the battery # 1 are basically in the same direction, and at this time, even if the pore volume of the positive electrode is increased. This indicates that the discharge capacity of the battery cannot be improved.

  When the pore volume of the positive electrode is the same, battery # 5 having a barium sulfate content of 4.2 mass% in the negative electrode active material is compared with battery # 2 having a barium sulfate content of 3.0 mass%. As a result, the discharge capacity of battery # 5 was lower at room temperature (25 ° C.), but the discharge capacity of battery # 5 was somewhat higher than that of battery # 2 at low temperature (−15 ° C.). This indicates that barium sulfate can improve the charge / discharge characteristics of the negative electrode to some extent under low temperature conditions.

  In order to further elucidate the mechanism of the influence of the pore structure of the positive electrode active material on the charge / discharge performance, the inventors of the present application conducted detailed studies on the pore size distribution of the positive electrodes A, B and C. Based on the mercury intrusion method, the graph of the differential curve of the pore distribution of the positive electrode active material shown in FIG. 3 was obtained. And the integration process was performed with respect to the graph of the differential curve of FIG. 3, and the graph of the integral curve shown in FIG. 4 was obtained.

From the graph of the differential curve in FIG. 3, it can be seen that the positive electrode A having a total pore volume of 0.085 cm ³ / g of the positive electrode active material reaches a peak in the vicinity of a pore diameter of 0.09 μm. Means that the change rate of the pore volume at the pore diameter of 0.09 μm is the maximum. On the other hand, a total pore volume for the positive electrode B of 0.110cm ³ / g, see that the pore volume in the vicinity of a pore diameter 0.8μm is peaked, the total pore volume of 0.122cm ³ / g Regarding the positive electrode C, it can be seen that the pore volume reaches a peak in the vicinity of the pore diameter of 2 μm.

  Further, the pore size distribution of the negative electrode active materials of the batteries # 1 to # 6 was similarly measured by a mercury intrusion method. The results are shown in FIG. Since the negative electrode active materials of the batteries # 7 and # 8 are the same as those of the battery # 6, illustration is omitted. As shown in FIG. 5, the pore volume of the negative electrode active material has two peaks in the vicinity of a pore diameter of 1.2 μm and 1.7 μm, respectively, but no peak exists in the vicinity of 0.8 μm.

  Usually, at room temperature, the smaller the total pore volume of the positive electrode active material, the smaller the amount of electrolyte solution that can be accommodated, and the more difficult it is to diffuse sulfate ions that contribute to the electrode reaction. Therefore, in general, in order to improve the discharge characteristics of the positive electrode, a method of increasing the total pore volume of the positive electrode active material to increase the amount of the electrolyte is adopted, thereby improving the discharge characteristics.

However, as a result of investigations, the inventors of the present application have found that the discharge characteristics of the battery cannot be improved even when the total pore volume of the positive electrode active material is increased at low temperatures. This is because the viscosity of the electrolyte increases at low temperatures, and the effectiveness of the pore size is the main factor affecting the diffusion of the electrolyte. The positive electrode B having a pore volume of 0.110 cm ³ / g has many pores having a pore diameter of 0.8 μm, and the specific pore diameter is suitable for the passage of sulfate ions at a low temperature. The charge / discharge characteristics of the positive electrode can be improved.

  From the differential curve graph of FIG. 3 and the integral curve graph of FIG. 4, the larger the total pore volume of the positive electrode active material, the larger the pore volume peak in the differential curve shifts to the larger pore diameter. It can also be seen that the smaller the volume, the more the pore volume peak in the differential curve shifts to the smaller pore size. The size of the total pore volume of the positive electrode active material reflects to some extent the size of the pore diameter of a large number of pores existing in the porous body of the positive electrode active material. Therefore, in the present invention, the pore volume of the positive electrode is appropriately reduced to fall within an appropriate range so that the porous body of the positive electrode active material is suitable for the passage of sulfate ions (around 0.8 μm). Have a large number of pores.

  If the total pore volume is too large, the amount of the electrolyte increases and the utilization factor of the positive electrode active material increases, but the adhesive force between the positive electrode active materials decreases and the cycle life characteristics of the battery tend to deteriorate. On the other hand, if the total pore volume is too small, the electrolyte solution is too small and the movement of sulfate ions is hindered, the utilization rate of the positive electrode active material is lowered, and the cycle life characteristics tend to be lowered.

On the other hand, it can be seen from FIG. 5 that since the negative electrode does not have pores having the specific pore diameter, the ionic conductivity of the electrolytic solution is inferior, and the balance of ionic conductivity between the positive and negative electrodes is lost. Therefore, in the present invention, it is necessary to increase the content of barium sulfate in the negative electrode active material. By increasing the BaSO ₄ content, the discharge product, that is, lead sulfate, is finely divided, and the affinity between the negative electrode and the electrolyte is increased. Thus, the charge / discharge characteristics of the negative electrode are improved, thereby balancing the charge / discharge characteristics of the positive electrode and the negative electrode, and a lead-acid battery having excellent discharge capacity and charge acceptance at low temperatures is obtained.

Therefore, in the present invention, the total pore volume of the positive electrode active material is preferably in the range of 0.087 to 0.120 cm ³ / g, and may be in the range of 0.090 to 0.110 cm ³ / g. More preferred. By keeping the total pore volume of the positive electrode active material within the above range, it can be ensured that a large number of pores having a pore diameter of 0.8 μm are present in the positive electrode active material. Since the pores having the specific pore diameter are suitable for passing sulfate ions at a low temperature, it is easy to cause the positive electrode to perform a discharge reaction.

  The fact that a large number of pores having a pore diameter of 0.8 μm are present in the positive electrode active material can be determined by a differential curve graph as shown in FIG. Specifically, in the graph of the differential curve showing the pore distribution of the positive electrode active material obtained by the mercury intrusion method, a peak appears in the pore volume in the vicinity of the pore diameter of 0.8 μm. Here, 0.8 μm includes the range of 0.2 μm before and after that, that is, the range of 0.6 to 1.0 μm, and preferably includes the range of 0.1 μm before and after that, that is, 0.7 to The range is 0.9 μm.

  In addition, the fact that there are a large number of pores having a pore diameter of 0.8 μm in the positive electrode active material can also be determined by a graph of an integral curve as shown in FIG. The presence of a large number of pores having a pore diameter of 0.8 μm means that the pore volume having a pore diameter of 0.2 to 2.0 μm occupies 45% or more of the total pore volume, and more preferably It is 50% or more, and 55% or more is particularly preferable.

  The size of the pore volume of the positive electrode also affects the cycle life of the battery. When the pore volume is too large, the mechanical strength of the electrode plate is lowered and the cycle life of the battery is shortened. In the present invention, since the pore volume smaller than that of the prior art is adopted, the mechanical strength of the positive electrode is increased, which is advantageous for improving the cycle life of the battery.

  On the other hand, in the negative electrode of the present invention, it is preferable to add 3.2 to 4.8% by mass of barium sulfate as a nucleating agent with respect to the negative electrode active material. If the barium sulfate content is too high, the amount of the negative electrode active material is relatively reduced, and the structure becomes too dense, so that the charge acceptability at low temperatures is deteriorated, and the discharge capacity of the battery is also small. turn into. On the other hand, when the content of barium sulfate in the negative electrode active material is too small, the role as a nucleating agent cannot be fully exhibited, and the solidified lead lump becomes large, so that the charge acceptability is also lowered.

  In the present invention, the range of the pore volume of the positive electrode and the range of the barium sulfate content in the negative electrode active material are in a specific combination, so that an excellent discharge capacity and charge acceptance can be obtained at low temperatures. I have a lead-acid battery that I have.

  Furthermore, by adding acetylene black to the negative electrode active material, the conductivity of the negative electrode can be improved, and the discharge capacity, charge acceptance, and cycle life characteristics of the lead-acid battery at low temperatures can be improved. The acetylene black content in the negative electrode active material is preferably 0.3 to 2.0% by mass. When there is too little content of acetylene black, the electroconductivity of a negative electrode will worsen and charge / discharge performance will worsen. On the other hand, when there is too much content of acetylene black, there exists a problem that it is difficult to produce.

  Further, a lignin surfactant may be further added to the negative electrode active material. By adding lignin to the negative electrode active material, shrinkage of the negative electrode active material (Pb) can be prevented, and the cycle life of the battery can be further improved. There is no restriction | limiting in particular in lignin type-surfactant content in a negative electrode active material, For example, although 0-5 mass% may be sufficient, if it is 0.1-2.0 mass%, 0.2- More preferably, it is 0.5 mass%. However, even if lignin is not added, practically sufficient cycle life characteristics can be obtained.

  In the present invention, the electrode plate group is generally composed of 5 to 8 positive electrodes and 6 to 9 negative electrodes. In order to improve the charge / discharge characteristics of a lead-acid battery at a low temperature, the inventors of the present application have a ratio of the total weight of the negative electrode active material applied to the negative electrode to the total weight of the positive electrode active material applied to the positive electrode (that is, the positive electrode active material). It has been found that there is an appropriate range in the weight ratio of the negative electrode active material to the negative electrode active material. The weight ratio is preferably 0.7 to 0.95, and more preferably 0.75 to 0.90. The larger the weight ratio, the smaller the weight of the positive electrode active material relative to the negative electrode active material. Therefore, when the weight ratio is larger than 0.95, the total pore volume of the positive electrode active material is too small, and the amount of the electrolyte flowing into the positive electrode is reduced, so that the discharge capacity of the battery itself is reduced. On the other hand, if the weight ratio is less than 0.7, the total pore volume of the positive electrode active material is too large, and most of the electrolyte flows into the positive electrode and less electrolyte flows into the negative electrode. And the low-temperature discharge capacity also decreases.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples and comparative examples in order to further describe the features and effects of the present invention. However, the present invention is not limited to these specific examples.
Example 1
(Preparation of positive electrode)
An expanded lattice having an ear portion manufactured by the expanding method is defined as a positive electrode lattice (vertical: 137 mm, horizontal: 140 mm, thickness: 2.8 mm). In addition, the lead powder (oxidation degree: about 80%) of raw material and sulfuric acid are mixed at a weight ratio of 100: 5 to obtain a lead paste, and 12% by mass of the lead powder of the raw material during kneading of the lead paste Water was added to obtain a positive electrode active material paste (hereinafter simply referred to as positive electrode lead paste).

  The expanded grid was filled with 183.6 g of positive lead paste along the length of the grid. Thereafter, the grid filled with the lead paste was cut into a predetermined size and shape, and aged and dried to obtain an unformed positive electrode (vertical: 137 mm, horizontal: 140 mm).

(Preparation of negative electrode)
An expanded lattice having an ear portion manufactured by the expanding method is defined as a negative electrode lattice (vertical: 137 mm, horizontal: 140 mm, thickness: 1.8 mm). In addition, raw material lead powder (oxidation degree: about 80%), water, and sulfuric acid were mixed at a weight ratio of 100: 11: 2. In addition, 4.2% by mass of barium sulfate (manufactured by Qingdao Dongfeng Chemical Co., Ltd.), 0.2% by mass of lignin (sodium lignin sulfonate, manufactured by Sanmic Shoji Co., Ltd.) as an expanding agent and 1% by mass as a conductive material % Of acetylene black (manufactured by Kanka Chemical Co., Ltd.) was added and kneaded to obtain a negative electrode active material paste (hereinafter simply referred to as negative electrode lead paste).

  Then, after 145 g of negative electrode lead paste was filled in the negative electrode lattice, aging and drying were performed to obtain an unchemically formed negative electrode.

(Production of lead-acid battery)
The seven positive electrodes obtained as described above were inserted into seven bag-shaped separators made of acrylonitrile-based fiber nonwoven fabric subjected to hydrophilic treatment, and alternately with the eight negative electrodes obtained as described above. And an electrode plate group was obtained by inserting a chip-like separator made of glass fiber between the bag-like separator and the negative electrode. In the electrode plate group, the ears of the electrode plates of the same polarity were welded to the connecting members to form bus bars. Thereafter, the electrode plate groups were accommodated one by one in six single cell tanks partitioned by partition walls in the battery case.

  Thereafter, 1030 ml of sulfuric acid having a concentration of 1.215 g / ml as an electrolytic solution is injected into each single cell, and then a battery cap (inner lid and upper lid) is attached to the opening of the cell tank and sealed, and a chemical conversion treatment is performed. A lead storage battery having a capacity of 100 Ah was obtained. This is referred to as the battery of Example 1.

<Measurement of pore volume of positive electrode>
The pore volume of the positive electrode was measured by the mercury intrusion method in the following steps. First, after the battery produced as described above was fully charged, the battery was disassembled and the electrode plate group was taken out of the battery, and the electrode plate group was divided into a positive electrode, a negative electrode, and a separator. The positive electrode and the negative electrode were immersed in water to remove the sulfuric acid component contained in the electrode plate, and then the positive electrode and the negative electrode were dried. At this time, the negative electrode was dried in vacuum. A predetermined amount of the active material was weighed from the dried electrode plate and measured with a mercury intrusion porosimeter (manufactured by Micromeritics, AutoPore III9410 type fully automatic mercury intrusion porosimeter).

The pore volume of the positive electrode in the battery of Example 1 measured by the above steps was 0.087 cm ³ / g. According to the graph of the differential curve of the pore distribution, pores having a pore diameter of 0.8 μm were present in the positive electrode active material. It was confirmed that a relatively large number existed.

<Negative electrode / positive electrode active material weight ratio>
The weight of the active material in the negative electrode and the positive electrode after drying was measured, and the weight ratio of the negative electrode / positive electrode active material was calculated. The result was 0.8.

Example 2:
The amount of water added was changed in the kneading of the positive electrode lead paste so that the pore volume of the positive electrode obtained was 0.110 cm ³ / g. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a negative electrode and a lead storage battery were produced in the same manner as in Example 1. It was confirmed by the graph of the differential curve of the pore distribution that there were many pores having a pore diameter of 0.8 μm in the positive electrode active material.

Example 3:
The amount of water added was changed in the kneading of the positive electrode lead paste so that the pore volume of the positive electrode obtained was 0.120 cm ³ / g. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a negative electrode and a lead storage battery were produced in the same manner as in Example 1. It was confirmed by the graph of the differential curve of the pore distribution that there were many pores having a pore diameter of 0.8 μm in the positive electrode active material.

Comparative Example 1:
The amount of water added in the kneading of the positive electrode lead paste was changed so that the pore volume of the positive electrode obtained was 0.085 cm ³ / g. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a negative electrode and a lead storage battery were produced in the same manner as in Example 1. From the graph of the differential curve of the pore distribution, it was confirmed that there were very few pores having a pore diameter of 0.8 μm in the positive electrode active material.

Comparative Example 2:
The amount of water added in the kneading of the positive electrode lead paste was changed so that the pore volume of the positive electrode obtained was 0.122 cm ³ / g. Otherwise, a positive electrode was produced in the same manner as in Example 1, and a negative electrode and a lead storage battery were produced in the same manner as in Example 1. It was confirmed by the graph of the differential curve of the pore distribution that relatively few pores having a pore diameter of 0.8 μm were present in the positive electrode active material.

Example 4:
In production of the negative electrode, the barium sulfate content in the negative electrode active material was changed to 3.2 mass%. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 5:
In preparation of the negative electrode, the barium sulfate content in the negative electrode active material was changed to 4.8% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Comparative Example 3:
In production of the negative electrode, the barium sulfate content in the negative electrode active material was changed to 3% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Comparative Example 4:
In production of the negative electrode, the barium sulfate content in the negative electrode active material was changed to 5% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 6:
In the production of the negative electrode, the acetylene black content in the negative electrode active material was changed to 0.3% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 7:
In preparation of the negative electrode, the acetylene black content in the negative electrode active material was changed to 0.5% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 8:
In preparation of the negative electrode, the acetylene black content in the negative electrode active material was changed to 1.5% by mass. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 9:
In preparation of the negative electrode, the acetylene black content in the negative electrode active material was changed to 2.0 mass%. Otherwise, a negative electrode was produced in the same manner as in Example 2, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2. In this example, since the content of acetylene black was large, battery production was relatively difficult.

Example 10:
In the production of the negative electrode, a negative electrode was produced in the same manner as in Example 2 except that lignin was not added to the negative electrode active material, and a positive electrode and a lead storage battery were produced in the same manner as in Example 2.

Example 11:
The weight ratio of the negative electrode / positive electrode active material was changed to 0.7, and a positive electrode, a negative electrode, and a lead storage battery were fabricated in the same manner as in Example 2 except that.

Example 12:
The weight ratio of the negative electrode / positive electrode active material was changed to 0.75, and a positive electrode, a negative electrode, and a lead storage battery were produced in the same manner as in Example 2 except that.

Example 13:
The weight ratio of the negative electrode / positive electrode active material was changed to 0.9, and a positive electrode, a negative electrode, and a lead storage battery were produced in the same manner as in Example 2 except that.

Example 14:
The weight ratio of the negative electrode / positive electrode active material was changed to 0.95, and a positive electrode, a negative electrode, and a lead storage battery were fabricated in the same manner as in Example 2 except that.

<Battery performance test>
The batteries of Examples 1 to 14 and Comparative Examples 1 to 4 were tested for low temperature charge acceptability, low temperature discharge capacity, and cycle life characteristics at 25 ° C., respectively.

(1) Low temperature charge acceptability The low temperature charge acceptability of the battery was measured in the following steps.

  The fully charged battery was left at 0 ° C. for 10 hours or more, and discharged at a constant current of 0.25 C until the voltage dropped to 10.5 V. Ambient temperature was kept at 0 ° C. The discharge capacity at this time is referred to as “discharge capacity (1)”. Subsequently, charging was performed at a constant voltage of 14.7 V at 0 ° C. The maximum current was 0.3 C and the battery was charged for 10 hours. Thereafter, discharging was performed at 0 ° C. with a constant current of 0.25 C until the voltage dropped to 10.5 V. The discharge capacity at this time is referred to as “discharge capacity (2)”.

  While calculating the charge acceptance of the battery at low temperature by the following formula, the charge acceptance was evaluated according to the following criteria.

Charge acceptance (%) = Discharge capacity (2) / Discharge capacity (1) x 100%
Evaluation criteria:
Charge acceptability is 100%: Indicates that the performance is particularly excellent Charge acceptability is 90% or more and less than 100%: Indicates that the performance is good Charge acceptability is 80% or more and less than 90%: Performance is normal Although it indicates that it is practical, the charge acceptance is less than 80%: it indicates that it has not reached the practical level. (2) Low-temperature discharge capacity The low-temperature discharge capacity of the battery was measured in the following steps.

The fully charged battery was left in an environment of −15 ° C. within 1 hour after the completion of charging and left for 10 hours or more, and discharged at a current of I ₂₀ (5A). The ambient temperature of the battery was kept at -15 ° C. When the voltage reached 10.5 V, the discharge was stopped and the discharge time was recorded.

  While calculating the discharge capacity of the battery under low temperature by the following formula, the low temperature discharge capacity was evaluated according to the following criteria.

Low temperature discharge capacity (Ah) = discharge current (A) × discharge time (h)
Evaluation criteria:
Low temperature discharge capacity of 70 Ah or more: Indicates that the performance is particularly excellent Low temperature discharge capacity of 65 Ah or more and less than 70 Ah: Indicates that the performance is good Low temperature discharge capacity of 60 Ah or more and less than 65 Ah: Performance is normal, but practical It shows that it is possible Low temperature discharge capacity is less than 60 Ah: Indicates that it has not reached the practical level (3) Cycle life characteristics For each lead storage battery obtained in Examples 1-14 and Comparative Examples 1-4, A cycle life test was conducted under the following conditions.

Temperature: 25 ° C
Battery standard: 12V, 100Ah
Charging condition: Charge at a constant voltage of 14.7 V for a maximum of 16 hours Discharging condition: Perform a constant current discharge until the voltage drops to 10.5 V at a current rate of 0.25 C. The test was terminated when the discharge capacity dropped to 80% of the discharge capacity in the first cycle, and the number of charge / discharge cycles performed was recorded.

  The cycle life of the battery was evaluated according to the following criteria.

Evaluation criteria:
Cycle number of 500 or more: Indicates that the performance is particularly excellent Cycle number of 400 or more and less than 500: Indicates that the performance is satisfactory Cycle number of 200 or more and less than 400: Performance is normal, but is practical The number of cycles is less than 200: it indicates that it has not reached the practical level. Various parameters and battery performance tests and evaluation results for each of the above storage batteries are summarized in Table 2 below.

From Table 2, the battery of Comparative Example 1 has very few pores having a pore diameter of 0.8 μm, and the positive electrode has a pore volume of 0.085 cm ³ / g, which is the lower limit of the preferred range of the pore volume in the present invention. Since the amount of electrolyte is small and the diffusion resistance of sulfate ions is large, it can be seen that the discharge capacity of the battery is small and the charge acceptance at low temperatures is also poor. The battery of Comparative Example 2 also has very few pores having a pore diameter of 0.8 μm, and the positive electrode has a pore volume of 0.122 cm ³ / g, which exceeds the upper limit of the preferred range of the pore volume in the present invention. Since the number of large pores is relatively large, the amount of electrolyte flowing into the positive electrode is too large, and the amount of electrolyte flowing into the negative electrode is reduced, resulting in poor ionic conductivity. The capacity is also getting worse and the cycle life is a little lower.

In the battery of Comparative Example 3, the positive electrode pore volume (0.110 cm ³ / g) is within the preferred range of the present invention, but the barium sulfate content (3.0% by mass) in the negative electrode active material. Is below the lower limit of the range in the present invention. Therefore, since there is too little barium sulfate and the mass of the solidified negative electrode active material becomes large, the low-temperature charge acceptance is low, the balance of the discharge characteristics between the positive and negative electrodes is poor, and the low-temperature discharge capacity of the battery is also small. . On the other hand, in the battery of Comparative Example 4, although the pore volume (0.110 cm ³ / g) of the positive electrode is within the range of the present invention, the barium sulfate content (5.0% by mass) in the negative electrode active material is The upper limit of the range in the present invention is exceeded. Therefore, since there is too much barium sulfate, the amount of the negative electrode active material becomes relatively small, and the structure becomes too dense, the charge acceptability at low temperatures is deteriorated, and the discharge capacity of the battery is also reduced.

In the batteries of Examples 1-5, the pore volume of the positive electrode is within the range of the present invention ^{(0.087cm 3 /g~0.120cm 3 / g)} , and barium sulfate content of the anode active material Is within the range of the present invention (3.2 to 4.8% by mass), so that the balance of discharge characteristics between the positive and negative electrodes is good, and excellent in all aspects of low-temperature charge acceptance, low-temperature discharge capacity, and cycle life. The effect was obtained.

  From the comparison of Examples 2 and 6 to 9, when the acetylene black content in the negative electrode active material is 0.3 to 2.0% by mass, more preferably 0.5 to 1.5% by mass, the battery is charged at low temperature. It can be seen that even more remarkable effects are obtained in terms of acceptability and low-temperature discharge capacity.

  Moreover, since lignin was added to all of the negative electrode active materials of Examples 1 to 9 and 11 to 14 of the present invention, a further excellent effect was obtained in terms of battery cycle life. However, even in the battery of Example 10 to which no lignin was added, excellent effects were obtained in terms of low-temperature charge acceptability and low-temperature discharge capacity, and although the life characteristics were slightly deteriorated, there was no practical problem. .

  Further, from the comparison of Examples 11 to 14, the weight ratio of the negative electrode active material to the positive electrode active material is within the range of 0.7 to 0.95, more preferably within the range of 0.75 to 0.90. It can be seen that the balance of charge / discharge characteristics between the negative electrodes can be strengthened, and a more remarkable effect can be obtained.

  The lead acid battery of the present invention not only has good cycle life characteristics, but also has excellent discharge capacity and charge acceptance at low temperatures. Especially, the lead acid battery for energy storage in a natural energy system such as solar energy. Suitable for use.

Claims (12)

A group of plates,
An electrolyte solution impregnated in the electrode plate group,
The electrode plate group includes a plurality of negative electrodes, a plurality of positive electrodes, and a plurality of separators.
The negative electrode includes a negative electrode lattice and a negative electrode active material held by the negative electrode lattice,
The positive electrode includes a positive electrode lattice and a positive electrode active material held by the positive electrode lattice,
The separator is a lead acid battery for energy storage separating the positive electrode and the negative electrode,
The total pore volume of the positive electrode active material is 0.087 to 0.120 cm ³ / g,
The lead-acid battery for energy storage, wherein the negative electrode active material contains 3.2 to 4.8% by mass of barium sulfate.   2. The lead acid battery for energy storage according to claim 1, wherein the positive electrode active material has a large number of pores having a pore diameter of 0.8 μm.   In the graph of the differential curve of the pore distribution obtained by measuring the positive electrode active material by the mercury intrusion method, a peak appears in the pore volume within the range of the pore diameter of 0.7 μm to 0.9 μm, The lead acid battery for energy storage according to claim 2. The lead acid battery for energy storage according to claim 1, wherein a total pore volume of the positive electrode active material is 0.090 to 0.110 cm ³ / g.   The lead acid battery for energy storage according to any one of claims 1 to 4, wherein 0.3 to 2.0 mass% of acetylene black is contained in the negative electrode active material.   The energy storage device according to any one of claims 1 to 4, wherein the negative electrode active material further contains 0.1 to 2.0% by mass of a lignin surfactant. Lead acid battery.   5. The energy according to claim 1, wherein the weight ratio of the negative electrode active material to the positive electrode active material, that is, the negative electrode active material / the positive electrode active material is 0.7 to 0.95. Lead acid battery for storage.   The lead acid battery for energy storage according to any one of claims 1 to 4, wherein an expanded lattice is used at least for the positive electrode lattice. The separator comprises a bag-like separator made of synthetic fiber subjected to a hydrophilic treatment, and a chip-like separator made of glass fiber,
The bag separator contains the positive electrode,
The lead storage battery for energy storage according to any one of claims 1 to 4, wherein the chip-shaped separator is sandwiched between the bag-shaped separator and the negative electrode.   The lead acid battery for energy storage according to claim 9, wherein the synthetic fiber includes at least acrylonitrile-based fine fibers having a diameter of 0.5 μm to 2.0 μm.   The lead acid battery for energy storage according to claim 10, wherein the synthetic fiber further includes an acrylonitrile-based thick fiber having a diameter of 2.5 μm to 8.0 μm.   The lead acid battery for energy storage according to claim 11, wherein the content of the acrylonitrile-based fine fiber is greater than the content of the acrylonitrile-based thick fiber.