JP7424371B2 - Separators for liquid lead-acid batteries and liquid lead-acid batteries - Google Patents

Description

The present invention relates to a separator for a liquid lead-acid battery and a liquid lead-acid battery.

Lead-acid batteries are used in a variety of applications, including automotive and industrial applications. A lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between them, and an electrolyte. Separators for lead-acid batteries are required to have various performances.

For example, Patent Document 1 discloses a lead-acid battery including a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate, and the separator includes a base portion and the a negative electrode rib provided on a negative electrode surface of a base portion facing the negative electrode plate; and side end portions disposed on both sides of the base portion, the side end portions being at least partially connected to the base portion. The present invention proposes a lead-acid battery that has a thicker wall portion, and both ends of the negative electrode plate are located within the width of the thick wall portion when viewed from the thickness direction of the negative electrode plate.

Further, as the output of lead-acid batteries increases, the thickness of the electrodes forming the electrode group is becoming thinner, and the number of electrodes is increasing.

JP2017-33660A

For example, if the electrodes that make up the electrode group are thin and the number of electrodes is large, if the electrode plate is deformed, the edge of the electrode plate will come into strong contact with the separator, resulting in a short circuit (including a penetration short circuit due to dendrite formation). ) and other problems may occur.

When a thick wall portion is provided at the side end portion of the separator as in Patent Document 1, the puncture strength of the thick wall portion can be increased. However, it has become clear that the resistance of the separator increases and the CCA (cold cranking current) performance deteriorates.

One aspect of the present invention includes a main part and a pair of edges located at both ends of the main part in a first direction,
The thickness Tp of the pair of edge parts is larger than the thickness Tm of the main part,
The total pore volume is 0.8 cm ³ /g or more and 2.0 cm ³ /g or less,
The present invention relates to a separator for a liquid lead-acid battery, in which the ratio r1 of the pore volume of the first pores having a pore diameter of 0.1 μm or more and 10 μm or less to the total pore volume is 50% or more.

It is possible to provide a separator for a liquid lead-acid battery that can suppress deterioration in CCA performance while ensuring high puncture strength at the edges of the separator.

1 is a schematic plan view (a) of the external appearance of a separator according to an embodiment of the present invention, and a schematic cross-sectional view (b) thereof taken along line II. FIG. 2 is a schematic plan view (a) showing the positional relationship between a separator and a pair of electrode plates according to an embodiment of the present invention, and a schematic cross-sectional view (b) thereof taken along the line II-II. 1 is a partially cutaway perspective view showing the external appearance and internal structure of a liquid lead-acid battery according to an embodiment of the present invention.

In order to improve the problem of penetration short circuit, Patent Document 1 proposes that a separator is provided with a negative electrode rib and a thick portion, and the end of the negative electrode plate is located within the width of the thick portion. In addition, especially in idling stop (IS) applications such as idling stop system vehicles (hereinafter also referred to as ISS vehicles) where the engine is started many times and large current discharge is repeated, many thin electrode plates are stacked one on top of the other. Sometimes they form a group. In this case, the negative electrode current collector may curve at the end portion of the negative electrode plate and penetrate the separator, causing a short circuit. Such short circuits are particularly likely to occur near the bottom of the negative electrode plate. Note that the bottom part of the negative electrode plate is the bottom part of the negative electrode plate in the normal usage state of the lead-acid battery.

From the viewpoint of suppressing short circuits at the ends (or edge portions) of the separator, it is considered advantageous to increase the thickness of the edges as in Patent Document 1. Most charge/discharge reactions occur in the region of the electrode plate facing the main part of the separator (in other words, the part inside the edge). Therefore, it was thought that even if the thickness of the edge part was made larger than that of the main part, there would be little effect on the charge/discharge reaction.

However, the present inventors have found that even if the thickness of the edge of the separator is made larger than the thickness of the main part, the resistance of the separator increases and the CCA performance may deteriorate.

In view of the above, a separator for a liquid lead-acid battery according to one aspect of the present invention has a main part and a pair of edges located at both ends of the main part in the first direction. The thickness Tp is larger than the thickness Tm of the main portion. The total pore volume of the separator is 0.8 cm ³ /g or more and 2.0 cm ³ /g or less. The ratio r1 of the pore volume of pores having a pore diameter of 0.1 μm or more and 10 μm or less (hereinafter referred to as first pores) to the total pore volume is 50% or more.

Further, a liquid lead-acid battery according to another aspect of the present invention includes a positive electrode plate, a negative electrode plate, the separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte.

A separator, when laid out on a flat surface, is typically generally rectangular and has four major sides. In a liquid lead-acid battery under normal use, the angle between the bottom side of the separator housed in the battery and the direction toward the surface side of the electrolyte (or the opposite direction) is 90° ± 10°. Let the direction be the first direction. Note that the direction from the bottom side of the liquid lead-acid battery to the liquid surface side of the electrolytic solution (or the opposite direction) is defined as the second direction. The second direction is a direction parallel to the vertical direction when the lead acid battery is placed in a normal usage state. The first direction corresponds to a direction from one opposing side surface side to the other side surface side of the liquid lead-acid battery in normal use. In this case, both ends of the main portion where the pair of edges are located mean both ends of the main portion in the first direction.

According to the above aspect of the present invention, when the thickness of the edge portion of the separator is made larger than the thickness of the main portion, the total pore volume of the separator (hereinafter referred to as pore volume _Pt ) and the first pore volume By controlling the ratio r1 within a specific range, it is possible to suppress a decrease in CCA performance while ensuring high puncture strength at the edge. The reason why the decline in CCA performance is suppressed is that by controlling the pore volume _Pt of the separator and the ratio r1 of the first pores, the pore structure of the separator is optimized and the increase in resistance of the separator is suppressed. This is thought to be due to the

When the pore volume _Pt is less than 0.8 cm ³ /g, even if the edge thickness Tp is made larger than the main part thickness Tm and the first pore ratio r1 is 50% by volume or more, the CCA performance decreases. It has little effect on suppressing In other words, when the pore volume P _t is less than 0.8 cm ³ /g and when it is 0.8 cm ³ /g or more, it is necessary to make Tp larger than Tm and to control the ratio r1 of the first pores. The behavior of separators on performance varies widely. The effect of suppressing the decline in CCA performance as described above can only be obtained by setting the pore volume P _t to 0.8 cm ³ /g or more. Further, when the ratio r1 of the first pore volume is less than 50% by volume, even if Tp is made larger than Tm and the pore volume _Pt is set to 0.8 cm ³ /g or more, the decrease in CCA performance is suppressed. That is difficult.

Note that CCA is one of the indicators that indicates the performance of lead-acid batteries. For example, in the case of a lead-acid battery with a rated voltage of 12V, the terminal voltage after 30 seconds is 7 when discharged at a temperature of -18°C ± 1°C. This refers to the discharge current that reaches .2V.

Additionally, lead-acid batteries are sometimes used in an undercharged state called a partial state of charge (PSOC). For example, in IS applications such as ISS vehicles, lead-acid batteries will be used in PSOCs. In PSOC, since large current discharge is repeated, the diffusivity of the electrolyte tends to affect discharge performance and life performance. On the other hand, according to the lead-acid battery according to the above aspect of the present invention, it is possible to suppress a decrease in life performance (also referred to as IS life performance) when used in a PSOC. This is considered to be because the increase in resistance of the separator is suppressed and the diffusivity of the electrolyte is increased.

Note that the separator may have ribs or may not have ribs. A separator having ribs includes, for example, a base portion and a rib that stands up from the surface of the base portion. The ribs may be provided only on one surface of the separator or each base portion, or may be provided on both surfaces. The separator may be formed into a bag shape, or either the positive electrode plate or the negative electrode plate may be wrapped in the bag-shaped separator.

The ratio r1 of the first pores is the ratio of the pore volume of the first pores (hereinafter referred to as pore volume P ₁ ) to the pore volume P _t (=P ₁ /P _t ×100 (%)) It is. The pore volume P _t and the pore volume P ₁ are each measured by a mercury intrusion method on an unused separator or a separator taken out from a lead-acid battery in the early stage of use.

Note that in this specification, a battery in the early stage of use refers to a battery that has not been used for much time and has hardly deteriorated.

More specifically, the pore volume P _t and the pore volume P ₁ of the first pore are measured using a mercury porosimeter (Co., Ltd.) for a sample in which the main part of the separator is cut into a size of 20 mm in length x 5 mm in width. Measured using Autopore IV9510 (manufactured by Shimadzu Corporation). Note that the pressure range for measurement is 4 psia (≈27.6 kPa) or more and 60,000 psia (≈414 MPa) or less. In addition, the pore size range is 0.01 μm or more and 50 μm or less.

The edge thickness Tp is an average value obtained by measuring and averaging the thicknesses at five arbitrary locations on the edge of the separator. Similarly, the thickness Tm of the main portion is an average value obtained by measuring and averaging the thicknesses at five arbitrary locations of the main portion of the separator. Each thickness is determined using calipers. When the separator has ribs on the edge or main part, the thickness Tp of the edge and the thickness Tm of the main part are each the thickness of the base part. Each thickness is measured over a single section of separator. In a bag-shaped separator, when a welded portion is formed at the end in the first direction, the thickness of the edge is measured for the portion other than the welded portion.

As samples for measuring the pore volume P _t , the pore volume P ₁ , and the thicknesses Tp and Tm, an unused separator or a separator taken out from a disassembled lead-acid battery is used. Prior to measurement, the separator taken out from the lead-acid battery is washed and dried, and if necessary, cut to a desired size. The separator removed from the lead-acid battery is washed and dried using the following procedure. The separator taken out from the lead-acid battery is immersed in pure water for 1 hour to remove sulfuric acid in the separator. Next, the separator is taken out from the liquid in which it was immersed, and allowed to stand for 16 hours or more in a 25° C. environment to dry. In addition, when taking out a separator from a lead acid battery, a separator is taken out from a lead acid battery in a fully charged state.

In this specification, the fully charged state of a lead-acid battery is defined by JIS D 5301:2006. More specifically, the terminal voltage or temperature-converted electrolyte density during charging of a lead-acid battery measured every 15 minutes at a current of 1/20 of the value stated in the rated capacity is a significant figure three times in a row. A fully charged state is defined as a state in which the battery is charged until it reaches a constant value in three digits. Note that charging is performed with the lead-acid battery filled with electrolyte to a specified level.

A fully charged lead-acid battery is a fully charged chemical lead-acid battery. A lead-acid battery may be fully charged immediately after formation, or after some time has elapsed since formation (for example, a lead-acid battery that is in use (preferably at the beginning of use) may be fully charged after formation). ).

The ratio r1 of the first pores is, for example, 80% or less. In this case, high physical strength (tensile strength, etc.) of the separator can be ensured while keeping the resistance of the separator low. By ensuring high strength, the separator can be manufactured easily.

The pore volume P _t is preferably 1.8 cm ³ /g or less. This is because higher physical strength (tensile strength, etc.) of the separator can be ensured.

The difference between the thickness Tp of the edge portion and the thickness Tm of the main portion (=Tp−Tm) is preferably 0.05 mm or more. In this case, higher puncture strength can be obtained. Furthermore, an increase in the resistance of the separator is likely to become apparent. Even in such a case, according to the above aspect, it is possible to suppress an increase in the resistance of the separator and effectively suppress a decrease in CCA performance.

The thickness Tm of the main part of the separator is preferably 0.15 mm or more and 0.25 mm or less. In this case, it is easy to keep the resistance of the separator low, making it easy to ensure excellent CCA performance.

The separator may contain oil. The oil content in the separator is preferably 10% by mass or more. Even if the separator contains a certain amount of oil, the pore structure may cause the oil to escape from the separator during charging and discharging, the electrolyte may have too high diffusivity, or the separator may have low strength. Therefore, the high temperature overcharge life may be shortened. On the other hand, according to the above aspect, since the pore structure of the separator is optimized, it is possible to increase the diffusivity of the electrolyte and reduce the resistance of the separator while retaining oil within the separator. The oil held in the separator suppresses oxidative deterioration of the constituent materials of the separator even when overcharging at high temperatures, so an excellent high-temperature overcharge life can be ensured. Furthermore, since the resistance of the separator is reduced, it is advantageous in improving the startability of the lead-acid battery.

The separator preferably includes pores (hereinafter referred to as second pores) having a pore diameter of 0.03 μm or less. In this case, while ensuring the diffusibility of the electrolytic solution, it is possible to reduce oil leakage from the separator due to charging and discharging. The ratio r2 of the pore volume of the second pore (hereinafter referred to as pore volume _P2 ) to the pore volume _Pt is preferably 20% or more. When the ratio r2 is within such a range, high diffusivity of the electrolytic solution can be ensured while ensuring high oil retention during charging and discharging. Further, it becomes easier to ensure higher physical strength of the separator.

Note that the pore volume P ₂ is measured in the same manner as the pore volume P ₁ using the pore size range of 0.03 μm or less (or less than 0.03 μm) in the pore distribution. The ratio r2 is obtained from r2=P ₂ /P _t ×100 (%) in the same way as the ratio r1.

The oil content in the separator is the value measured on an unused separator or a separator that has been removed from a lead-acid battery, washed and dried in the same manner as above.

The oil content of the unused or dried separator is calculated by the following procedure. First, 0.5 g (initial sample mass: m ₀ ) of a sample obtained by cutting an unused or dried separator into strips is weighed and collected. Place the sample in an appropriately sized glass beaker and add 50 mL of n-hexane. Next, by applying ultrasonic waves to the sample in the beaker for about 30 minutes, the oil contained in the sample is eluted into n-hexane. The sample is taken out, dried in the atmosphere at room temperature (at a temperature of 20° C. or higher and 35° C. or lower), and then weighed to determine the mass (m ₁ ) of the sample after oil removal. Then, the oil content is calculated using the following formula.
Oil content (mass%) = (m ₀ - m ₁ )/m ₀ ×100

Note that when the separator has ribs, the sample is taken from the area of the main part that does not have ribs.

In the lead-acid battery according to the above aspect, for example, the widths of the positive electrode plate and the negative electrode plate are both larger than the width of the main part of the separator. In this case, the extreme end or corner of the electrode plate in the first direction does not face the main part, but faces the pair of edges. Further, by arranging only the pair of edges to face the electrode plates, the internal resistance of the lead-acid battery can be limited to the lowest possible level.

In the above aspect, since the thickness of the edge of the separator is greater than the thickness of the main portion, short circuits at the edge can be effectively suppressed, and the electrolyte in the separator has high diffusivity. Therefore, it is suitable for use as a lead-acid battery for IS, which requires high electrolyte diffusivity due to frequent charging and discharging. In a lead-acid battery for IS, even if the negative electrode current collector is easily curved, short circuits at the edges can be effectively suppressed. Furthermore, since the resistance of the separator is kept low while suppressing short circuits at the edges, it is also suitable for use in applications that require a large current. When starting a vehicle, a large amount of current is initially required. Therefore, lead-acid batteries are also particularly suitable for use in starting vehicles.

Hereinafter, a separator for a liquid lead acid battery and a liquid lead acid battery according to embodiments of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the following embodiments.

(separator)
FIG. 1 shows a schematic plan view (a) of the external appearance of a separator 100 according to an embodiment of the present invention, and a schematic cross-sectional view (b) thereof taken along line Ib-Ib. FIG. 2 is a schematic plan view (a) showing the positional relationship between a separator and a pair of electrode plates (E), and a schematic cross-sectional view (b) thereof taken along line IIb-IIb.

Although it is not clear in FIG. 1, the separator 100 has a bag shape, and has a shape in which a sheet-like microporous membrane having an area twice that of the bag is folded in half at a fold line 101. That is, the sheet-like microporous membrane is divided by folds 101 into a first portion 100A and a second portion 100B that face each other. FIGS. 1A and 1B correspond to a schematic plan view and a schematic cross-sectional view of the first portion 100A, respectively. Note that the illustrated embodiment is only one aspect of the present invention, and a sheet-like separator other than a bag-like separator may be sandwiched between the negative electrode plate and the positive electrode plate.

The separator 100 has main parts 103 (width A) facing most of the positive electrode plate 2 and the negative electrode plate 3, respectively, and edges provided adjacent to the main part 103 on both sides of the main part 103 so as to intersect with the fold line 101. 105 (width B). A part of the edge 105 (the end) is a welded part 105S (width S), and the welded parts 105S facing each other by folding in half are welded to each other.

The main portion 103 includes a first base portion 103b and a plurality of main ribs 103r provided on one surface (here, the outer surface of the bag; the same applies hereinafter) of the first base portion 103b.

The edge portion 105 located outside both ends of the main portion 103 in the first direction D1 includes a second base portion 105b and a plurality of mini-ribs 105r provided on one surface of the second base portion 105b. The protruding height of the mini-rib 105r is smaller than the protruding height of the main rib 103r.

The main ribs 103r and the miniribs 105r have the effect of increasing the diffusivity of the electrolyte near the electrode plate, for example. The main ribs 103r and the mini-ribs 105r are both provided only on the surface of the separator or each base portion facing the positive electrode plate 3, and the tips of the mini-ribs are arranged substantially flush with each other. The surface of the separator facing the negative electrode plate 2 is substantially flat overall. Note that each of the main ribs 103r and mini ribs 105r is not essential.

Note that, unlike the illustrated example, the main ribs 103r and the mini ribs 105r may also be provided on the surface of each base portion facing the negative electrode plate 2 (ie, on the inside of the bag). Further, the main ribs 103r and the mini ribs 105r may be provided only on the surface of each base portion facing the negative electrode plate 2. From the viewpoint of efficiently suppressing oxidative deterioration of the separator, the surface of the separator having ribs may face the positive electrode plate.

In FIG. 2, the widths of the negative electrode plate 2 and the positive electrode plate 3 (both indicated by E) are larger than the width A of the main part 103 of the separator 100, and the widths of the negative electrode plate 2 and the positive electrode plate 3 are both larger than the width A of the main part 103 of the separator 100, and the widths of the negative electrode plate 2 and the positive electrode plate 3 are The portion faces the edge portion 105 with a slight width d. In this case, the resistance of the separator tends to increase, but by controlling the pore structure of the separator, the resistance can be effectively reduced and excellent CCA performance can be ensured. Further, a high short circuit prevention effect can be obtained at the edges.

Note that the embodiment shown in FIGS. 1 and 2 is only one aspect of the present invention, and for example, a sheet-like separator other than a bag-like separator may be sandwiched between the negative electrode plate and the positive electrode plate.

For example, a separator is made by extruding a resin composition containing a polymer material (hereinafter also referred to as a base polymer), a pore-forming agent, and a penetrating agent (surfactant) into a sheet, and then removing the pore-forming agent. It can be obtained by Removal of at least some of the pore forming agent forms micropores in the matrix of the base polymer. The resin composition may further contain inorganic particles.

The ribs may be formed into a sheet during extrusion molding, and after the resin composition is molded into a sheet or after the pore-forming agent is removed, the sheet is pressed with a roller having a groove corresponding to each rib. It may be formed by

The base polymer is not particularly limited as long as it is used for separators of lead-acid batteries, but polyolefins are often used. Examples of polyolefins include polymers containing at least ethylene and/or propylene as monomer units. As the polyolefin, for example, polyethylene, polypropylene, and a copolymer containing ethylene and/or propylene as a monomer unit (eg, ethylene-propylene copolymer, etc.) are more preferable. Among these, it is preferable to use at least polyethylene. Polyolefins and other polymers may be used in combination.

Preferred examples of the inorganic particles include ceramic particles such as silica, alumina, and titania.

The content of inorganic particles in the separator is, for example, 40% by mass or more, and may be 50% by mass or more. The content of inorganic particles is, for example, 80% by mass or less, and may be 75% by mass or less, or 70% by mass or less.

The content of inorganic particles in the separator is 40% by mass or more (or 50% by mass or more) and 80% by mass or less, 40% by mass or more (or 50% by mass or more) and 75% by mass or less, or 40% by mass or more (or 50% by mass or more) and 70% by mass or less.

The content of inorganic particles in the separator is determined by the following procedure using the separator taken out from the lead-acid battery, washed and dried as a measurement sample. After accurately weighing the measurement sample, it is placed in a platinum crucible and heated with a Bunsen burner until no white smoke is emitted. Next, the sample is heated in an electric furnace (in an oxygen stream, at 550° C.) for about 1 hour to incinerate, and the ashed product is weighed. The ratio of the mass of the ash to the mass of the above measurement sample is calculated and taken as the content (mass%) of the above inorganic particles.

Examples of the pore-forming agent include liquid pore-forming agents and solid pore-forming agents. Pore-forming agents may be used alone or in combination of two or more. A liquid pore-forming agent and a solid pore-forming agent may be used together. As the liquid pore-forming agent, mineral oil, synthetic oil, etc. are preferable. Examples of the liquid pore-forming agent include paraffin oil and silicone oil. Examples of the solid pore-forming agent include polymer powder.

The amount of pore-forming agent in the separator may vary depending on the type, so it cannot be determined unconditionally, but it is, for example, 30 parts by mass or more per 100 parts by mass of the base polymer. Further, the amount of pore-forming agent is, for example, 60 parts by mass or less.

The oil content in the separator is, for example, 8% by mass or more. From the viewpoint of easily ensuring an excellent high-temperature overcharge life, the content of oil in the separator is preferably 10% by mass or more, more preferably 13% by mass or more. The content of oil in the separator is, for example, 20% by mass or less, preferably 18.0% by mass or less, and more preferably 17.5% by mass or less. When the oil content is within this range, the resistance of the separator can be further reduced.
Note that the oil content in the separator is measured by the procedure described above.

The oil content in the separator is 8% by mass or more (or 10% by mass or more) and 20% by mass or less, 8% by mass or more (or 10% by mass or more) and 18.0% by mass or less, and 8% by mass or more (or 10% by mass or more). (mass% or more) 17.5 mass% or less, 13 mass% or more and 20 mass% or less (or 18.0 mass% or less), or 13 mass% or more and 17.5 mass% or less.

The surfactant as a penetrant may be, for example, an ionic surfactant or a nonionic surfactant. One type of surfactant may be used alone, or two or more types may be used in combination.

The amount of penetrant in the separator is, for example, 0.1 part by mass or more, and may be 0.5 part by mass or more, per 100 parts by mass of the base polymer. Further, the amount of penetrant is, for example, 10 parts by mass or less, and may be 5 parts by mass or less.

The amount of penetrant in the separator is 0.1 parts by mass or more (or 0.5 parts by mass or more) and 10 parts by mass or less, or 0.1 parts by mass or more (0.5 parts by mass or more) per 100 parts by mass of the base polymer. It may be 5 parts by mass or less.

The content of the penetrating agent in the separator is, for example, 0.01% by mass or more, and may be 0.1% by mass or more. The content of the penetrating agent is, for example, 5% by mass or less, and may be 10% by mass or less.

The content of the penetrating agent in the separator is 0.01% by mass or more (0.1 parts by mass or more) and 10% by mass or less, or 0.01% by mass or more (0.1 parts by mass or more) and 5% by mass or less. There may be.

The content of the penetrant in the separator is determined by the following procedure using an unused separator or a separator taken out from the lead acid battery according to the above procedure, washed and dried as a measurement sample. First, a measurement sample having an area of about 15 cm ² is accurately weighed, and then dried for 12 hours or more in a reduced pressure environment lower than atmospheric pressure at room temperature (at a temperature of 20° C. or higher and 35° C. or lower). The dried material is placed in a platinum cell, set in a thermogravimetric measuring device, and heated from room temperature to 800° C. at a heating rate of 10 K/min. The amount of weight loss when the temperature is raised from room temperature to 250 ° C. is taken as the mass of the penetrant, and the ratio of the mass of the penetrant to the mass of the above measurement sample is calculated, and the content (mass%) of the above penetrant is calculated. shall be. As a thermogravimetric measuring device, T. A. Q5000IR manufactured by Instrument Corporation is used.

From the viewpoint of easily ensuring the strength of the separator, the thickness Tm of the main portion 103 (that is, the first base portion 103b) is, for example, 0.15 mm or more. From the viewpoint of keeping the resistance of the separator low, the thickness Tm is advantageously, for example, 0.25 mm or less, and more preferably 0.20 mm or less.

The thickness Tm may be 0.15 mm or more and 0.25 mm or less, or 0.15 mm or more and 0.20 mm or less.

The thickness Tp only needs to be larger than the thickness Tm, and (Tp-Tm) is, for example, 0.03 mm or more. (Tp-Tm) is preferably 0.05 mm or more, and may be 0.06 mm or more or 0.07 mm or more. When (Tp-Tm) is within such a range, an increase in resistance in the separator is likely to become apparent. According to the above aspect of the present invention, high electrolyte diffusivity can be ensured, so even when (Tp-Tm) is in this range, an increase in resistance of the separator can be effectively suppressed. Moreover, it is easy to ensure high puncture strength at the edge. (Tp-Tm) is, for example, 0.25 mm or less, may be 0.22 mm or less or 0.21 mm or less, may be 0.16 mm or less or 0.15 mm or less, and may be 0.10 mm or less It may be. When (Tp-Tm) is within such a range, it is easy to keep the resistance of the separator low.

(Tp-Tm) is 0.03 mm or more and 0.25 mm or less (or 0.22 mm or less), 0.05 mm or more and 0.25 mm or less (or 0.22 mm or less), 0.06 mm or more and 0.25 mm or less (or 0 .22mm or less), 0.07mm or more and 0.25mm or less (or 0.22mm or less), 0.03mm or more and 0.21mm or less (or 0.16mm or less), 0.05mm or more and 0.21mm or less (or 0.16mm ), 0.06 mm or more and 0.21 mm or less (or 0.16 mm or less), 0.07 mm or more and 0.21 mm or less (or 0.16 mm or less), 0.03 mm or more and 0.15 mm or less (or 0.10 mm or less) , 0.05 mm or more and 0.15 mm or less (or 0.10 mm or less), 0.06 mm or more and 0.15 mm or less (or 0.10 mm or less), or 0.07 mm or more and 0.15 mm or less (or 0.10 mm or less) There may be.

The height of the main rib 103r is, for example, 0.4 mm or more. Moreover, the height of the main rib 103r may be 1.2 mm or less.

The height of the mini-rib 105r is, for example, 0.05 mm or more. Moreover, the height of the mini-rib 105r may be 0.3 mm or less.

The height of each rib is the height of the portion protruding from the main surface of each base portion (protrusion height). The height of each rib is determined by averaging the heights of the ribs from the base portion measured at ten arbitrarily selected points on the rib on one main surface of each base portion.

As with the thicknesses Tp and Tm, the height of each rib is determined for an unused separator or a separator that has been taken out from a lead-acid battery and washed and dried according to the above-described procedure.

The ribs may be formed on the sheet during extrusion molding, or may be formed by pressing the sheet with a roller having grooves corresponding to the ribs after forming the sheet into a sheet or after removing the pore-forming agent. good.

If the difference between the width E of each electrode plate in the first direction and the width A of the main part in the first direction (=EA) is, for example, 1 mm or more, the effect of preventing short circuits due to the edges can be easily obtained. On the other hand, the resistance of the separator tends to increase. Even in such a case, according to the above aspect, by optimizing the pore structure of the separator, the effect of reducing resistance can be effectively obtained, and excellent CCA performance can be ensured. (EA value) may be 2 mm or more. From the viewpoint of easily securing a higher CCA value, the (EA) value is preferably 10 mm or less, and may be 8 mm or less.

The (EA) value may be 1 mm or more and 10 mm or less, 1 mm or more and 8 mm or less, 2 mm or more and 10 mm or less, or 2 mm or more and 8 mm or less.

The pore volume P _t of the separator is 0.8 cm ³ /g or more, and may be 1.0 cm ³ /g or more from the viewpoint of ensuring higher CCA performance. When the pore volume _Pt is less than 0.8 cm ³ /g, even if the thickness Tp of the edge is made larger than the thickness Tm of the main part and the ratio of the first pores is 50% by volume or more, the CCA performance will not deteriorate. Almost no suppressive effect can be obtained. The pore volume P _t of the separator is 2.0 cm ³ /g or less. If the pore volume P _t exceeds 2.0 cm ³ /g, the physical strength of the separator will be weakened, which is disadvantageous in manufacturing. From the viewpoint of easily ensuring higher physical strength of the separator, the pore volume P _t is preferably 1.9 cm ³ /g or less, more preferably 1.8 cm ³ /g or less. If the strength of the separator decreases, it will break during the high temperature overcharge test, and the high temperature overcharge life will also be shortened.

The pore volume P _t of the separator is 0.8 cm ³ /g or more and 2.0 cm ³ /g or less, 0.8 cm ³ /g or more and 1.9 cm ³ /g or less, and 0.8 cm ³ /g or more and 1.8 cm ³ /g or less, 1.0cm ³ /g or more and 2.0cm ³ /g or less, 1.0cm ³ /g or more and 1.9cm ³ /g or less, or 1.0cm ³ /g or more and 1.8cm ³ /g or less There may be.

The pore volume _Pt can be adjusted by adjusting the affinity of the polymer material with the pore-forming agent and/or the penetrating agent, selecting the type and/or particle size of the inorganic particles, adjusting the amount of the penetrating agent, It can be adjusted by adjusting and/or the amount of pore-forming agent removed. Generally, the pore volume _Pt of the separator changes depending on the amount of the remaining pore-forming agent. If there is less pore-forming agent remaining in the separator, the number of pores in the separator will increase, and the resistance of the separator will decrease, but the physical strength will decrease. On the other hand, if there is a large amount of pore-forming agent remaining in the separator, the number of pores in the separator will decrease and the resistance will increase, but the physical strength will improve. Therefore, when removing a portion of the pore-forming agent, it is preferable to control the amount removed.

The ratio r1 of the first pores is 50% or more. When the ratio r1 is less than 50% by volume, it is difficult to suppress the deterioration of CCA performance even if Tp is made larger than Tm and the pore volume _Pt is set to 0.8 cm ³ /g or more. From the viewpoint of easily ensuring higher CCA performance, the ratio r1 is preferably 55% or more, and may be 60% or more. The ratio r1 is, for example, 80% or less. From the viewpoint of easily ensuring higher physical strength, the ratio r1 is preferably 75% or less.

Even if the ratio r1 is 50% to 80%, 50% to 75%, 55% to 80%, 55% to 75%, 60% to 80%, or 60% to 75% good.

The separator can include second pores. In addition to controlling the pore volume Pt and ratio r1, the presence of the second pores ensures the diffusivity of the electrolyte and keeps the resistance low, while also reducing the leakage of oil from the separator during charging and discharging. can do. Therefore, it becomes easier to achieve both low resistance of the separator and excellent high-temperature overcharge life.

The ratio r2 of the second pores is preferably 20% or more, more preferably 23% or more or 25% or more. When the ratio r2 is within such a range, it becomes easier to retain oil and to ensure high diffusivity of the electrolytic solution. From the viewpoint of balance with the ratio r1, the ratio r2 is, for example, 50% or less, and may be 45% or less or 40% or less.

Ratio r2 is 20% to 50%, 20% to 45%, 20% to 40%, 23% to 50%, 23% to 45%, 23% to 40%, 25% to 50 % or less, 25% or more and 45% or less, or 25% or more and 40% or less.

The pore structure and ratio r1 in the separator can be adjusted to adjust the affinity between the base polymer and the pore-forming agent and/or penetrating agent, to adjust the dispersibility of the pore-forming agent, and to adjust the type and/or particle size of the inorganic particles. Select the diameter, select the type of penetrant, adjust the amount of penetrant, and/or adjust the amount of functional groups and/or atoms, etc. present on the surface of the inorganic particle. It can be adjusted by

The ratio r2 can also be adjusted in the same manner as the ratio r1. From the viewpoint of adjusting the ratio r2, although the reason is not clear, for example, if the amount of -ONa groups on the surface of the inorganic particles is reduced (for example, the Na content in the separator is 1000 μg/cm 3 or less or 500 μg/cm ³ or less) ^cm3 ) is advantageous. More specifically, in the Log differential pore volume distribution of the separator, a unique peak appears in a region of 0.03 μm or less (preferably less than 0.03 μm (for example, around 0.02 μm)). From the viewpoint of easy control of the amount of -ONa groups, it is preferable to use silica particles as the inorganic particles.

Note that the Log differential pore volume distribution of the separator is determined from the pore volume P _t and the pore volume P ₁ of the first pores, which are measured in the same manner.

Although the separator may have pores other than the first pores and the second pores, the ratio of the volumes of the first pores and the second pores to the total pore volume is relatively large. For example, the sum of ratio r1 and ratio r2 may be 90% or more, 95% or more, or 98% or more. The sum of the ratio r1 and the ratio r2 is, for example, 100% or less.

(electrolyte)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may contain at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions. The electrolytic solution may be gelled, if necessary.

The specific gravity of the electrolytic solution at 20° C. is, for example, 1.10 g/cm ³ or more. The specific gravity of the electrolytic solution at 20° C. may be 1.35 g/cm ³ or less. Note that these specific gravity values are for the electrolyte of a fully charged lead-acid battery.

(positive electrode plate)
There are two types of positive electrode plates for lead-acid batteries: paste type and clad type.

The paste-type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive current collector. In the paste type positive electrode plate, the positive electrode material is the positive electrode plate minus the positive current collector. The positive electrode current collector may be formed in the same manner as the negative electrode current collector, and can be formed by casting lead or a lead alloy or processing a lead or lead alloy sheet.

A clad type positive electrode plate consists of multiple porous tubes, a core bar inserted into each tube, a positive electrode material filled in the tube into which the core bar is inserted, and a connecting seat that connects the multiple tubes. Equipped with. In a clad type positive electrode plate, the positive electrode material is the positive electrode plate excluding the tube, the core bar, and the connecting seat.

The lead alloy used for the positive electrode current collector is preferably a Pb--Ca alloy or a Pb--Ca--Sn alloy in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have lead alloy layers having different compositions, and may have a plurality of alloy layers. It is preferable to use a Pb--Ca alloy or a Pb--Sb alloy for the core metal.

The positive electrode material includes a positive active material (lead dioxide or lead sulfate) that develops capacity through a redox reaction. The positive electrode material may contain other additives as necessary.

An unformed paste-type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging and drying the same as in the case of a negative electrode plate. Thereafter, the unformed positive electrode plate is chemically formed. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.

The clad type positive electrode plate is formed by filling a tube into which a metal core is inserted with lead powder or lead powder in the form of a slurry, and connecting a plurality of tubes in series.

(Negative electrode plate)
The negative electrode plate of a lead-acid battery is composed of a negative electrode current collector and a negative electrode material. The negative electrode material is obtained by removing the negative electrode current collector from the negative electrode plate.

The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of processing methods include expanding processing and punching processing. It is preferable to use a negative electrode grid as the negative electrode current collector because it facilitates supporting the negative electrode material.

The lead alloy used for the negative electrode current collector may be any of a Pb-Sb alloy, a Pb-Ca alloy, and a Pb-Ca-Sn alloy. These lead or lead alloys may further contain at least one element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. as an additive element.

The negative electrode material contains a negative electrode active material (lead or lead sulfate) that develops capacity through a redox reaction, and may also contain an antishrink agent, a carbonaceous material (such as carbon black), barium sulfate, and the like. The amount of negative electrode material may include other additives as necessary.

The negative electrode active material in a charged state is spongy lead, but an unformed negative electrode plate is usually produced using lead powder.

The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying it to produce an unformed negative electrode plate, and then chemically converting the unformed negative electrode plate. The negative electrode paste is prepared by adding water and sulfuric acid to lead powder, an organic anti-shrink agent, and various additives as necessary, and kneading the mixture. In the aging step, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and high humidity.

Forming can be carried out by charging the electrode plate group including an unformed negative electrode plate while immersing the electrode plate group in an electrolytic solution containing sulfuric acid in a container of a lead-acid battery. However, chemical formation may be performed before assembling the lead-acid battery or the electrode plate group. Through chemical formation, spongy lead is formed.

(fiber mat)
The lead-acid battery may further include a fiber mat interposed between the positive and negative plates. Unlike a separator, a fiber mat includes a sheet-like fiber aggregate. As such a fiber aggregate, a sheet in which fibers insoluble in the electrolyte are entangled is used. Examples of such sheets include nonwoven fabrics, woven fabrics, and knitted fabrics. For example, 60% by mass or more of the fiber mat is made of fibers.

As the fiber, glass fiber, polymer fiber, pulp fiber, etc. can be used. Among polymer fibers, polyolefin fibers are preferred.

FIG. 3 is a partially cutaway perspective view showing the external appearance and internal structure of a liquid lead-acid battery according to an embodiment of the present invention.
The lead-acid battery 1 includes a battery case 12 that houses an electrode plate group 11 and an electrolyte (not shown). The inside of the battery case 12 is partitioned into a plurality of cell chambers 14 by a partition wall 13. Each cell chamber 14 houses one electrode plate group 11. The opening of the battery case 12 is closed with a lid 15 having a negative terminal 16 and a positive terminal 17. The lid 15 is provided with a liquid port plug 18 for each cell chamber. When refilling water, the liquid port stopper 18 is removed and the rehydration liquid is replenished. The liquid port plug 18 may have a function of discharging gas generated within the cell chamber 14 to the outside of the battery.

The electrode plate group 11 is constructed by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 with a separator 4 in between. Although a bag-shaped separator 4 that accommodates the negative electrode plate 2 is shown here, the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode shelf section 6 that connects a plurality of negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode shelf section that connects a plurality of positive electrode plates 3 in parallel. 5 is connected to the positive pole 7. The positive electrode column 7 is connected to a positive electrode terminal 17 outside the lid 15. In the cell chamber 14 located at the other end of the battery case 12 , the negative pole 9 is connected to the negative shelf 6 , and the through connector 8 is connected to the positive shelf 5 . The negative electrode column 9 is connected to a negative electrode terminal 16 outside the lid 15. Each through-connection body 8 passes through a through-hole provided in the partition wall 13 and connects the electrode plate groups 11 of adjacent cell chambers 14 in series.

The evaluation method for each characteristic will be explained below.

In the lead-acid battery according to the above aspect, while ensuring high puncture strength at the edge of the separator, the resistance of the separator is reduced, so that deterioration in CCA performance is suppressed. Further, it is also possible to suppress a decrease in IS life performance. Furthermore, it is also possible to ensure an excellent high temperature overcharge life. The puncture strength of the edge of the separator, the CCA performance of the lead-acid battery, the IS life performance, and the high temperature overcharge life are evaluated using the following procedure.

(1) Puncture strength In accordance with 7.5 "Puncture strength test" of JIS Z 1707:2019, fix the test piece including the edge of the separator with a jig, pierce the edge with the needle of the testing machine, Measure the maximum force (N) until the needle penetrates. Five test pieces are measured in the same manner, and the average value is determined to be the puncture strength. The test piece is prepared by cutting the separator into a size of 50 mm in length and 50 mm in width, including the edges. The test machine used is AGS-X, 10N-10kN manufactured by Shimadzu Corporation. A needle with a diameter of 1.0 mm and a semicircular tip (radius of 0.5 mm) is used, and the test speed is 50±5 mm/min. The jig used for fixing the test piece has a measuring part with a diameter of 10 mm on the top surface and a diameter on the bottom side of 20 mm.

(2) CCA performance Based on JIS D 5301:2006, the startability of the lead-acid battery is evaluated by the current value at which the terminal voltage becomes 7.2 V or more 30 seconds after the start of discharge according to the following procedure. The larger the current value, the higher the startability and the lower the resistance of the separator.
(a) After the battery is fully charged, place it in a cooling room at -18°C ± 1°C for at least 16 hours.
(b) After confirming that the electrolyte temperature of any cell in the center is -18°C±1°C, discharge for 30 seconds with CCA390A.
(c) Record the terminal voltage 30 seconds after the start of discharge.

(3) IS life performance In the following procedure, the number of cycles until the terminal voltage reaches 7.2V is used as an index of IS life performance. Note that the minute current discharge in (e) simulates dark current discharge when the engine is stopped.
(a) After fully charging, place the storage battery in a cooling room at 0°C ± 1°C for at least 16 hours, and then confirm that the electrolyte temperature of one of the cells in the center is 0°C ± 1°C. do.
(b) Discharge the storage battery at a discharge current of 300 A for 1.0 seconds.
(c) Discharge the storage battery at a discharge current of 25 A for 25 seconds.
(d) Charge the battery at a voltage of 14.0V for 30 seconds.
(e) Repeat the above (b) to (c) discharging and charging as one cycle. At this time, a minute current (20 mA) is discharged for 6 hours every 30 cycles.
(f) Find the number of cycles when the terminal voltage becomes less than 7.2V in (b) above.

(4) High-temperature overcharge lifespan A high-temperature overcharge durability test is performed to measure the lifespan of lead-acid batteries according to the following procedure.
(a) The battery is placed in an air bath at 75°C ± 3°C throughout the entire test period.
(b) Connect the storage battery to a life test device and continuously repeat the following discharging and charging cycles. This cycle of discharging and charging is defined as one lifetime (one cycle).
Discharge: 60 seconds ± 1 second at discharge current 25.0A ± 0.1A Charging: 600 seconds ± 1 second at charging voltage 14.80V ± 0.03V (limited current 25.0A ± 0.1A) (c) During test , and left for 56 hours every 480 cycles, and then continuous discharge was performed for 30 seconds with CCA390A, and the voltage at the 5th second was recorded. After that, charging in (b) is performed. Note that this discharging and charging are also added to the number of lifetimes (number of cycles).
(d) The end of the test is when it is confirmed that the voltage measured for the fifth second in the test (c) becomes 7.2 V or less and does not rise again, which is the end of the battery life.
In the evaluations (2) and (4) above, CCA is a discharge current determined such that discharge occurs at a temperature of -18° C.±1° C. and the voltage at the 30th second is 7.2 V or more.

[Example]
EXAMPLES Hereinafter, the present invention will be specifically explained based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

《Lead acid batteries E1 to E23 and R1 to R7》
(1) Preparation of negative electrode plate A negative electrode paste was prepared by mixing lead oxide, carbon black, barium sulfate, lignin, reinforcing material (synthetic resin fiber), water, and sulfuric acid. The negative electrode paste was filled into the mesh part of an expanded lattice made of antimony-free Pb-Ca-Sn alloy, aged and dried to obtain an unformed negative electrode plate with a width E of 100 mm, a height of 110 mm, and a thickness of 1.3 m. . The amounts of carbon black, barium sulfate, lignin, and synthetic resin fibers are 0.3% by mass, 2.1% by mass, 0.1% by mass, and 0.1% by mass, respectively, when measured in a fully charged state of preformed chemical. It was adjusted to be % by mass.

(2) Preparation of positive electrode plate A positive electrode paste was prepared by mixing lead oxide, reinforcing material (synthetic resin fiber), water, and sulfuric acid. The positive electrode paste was filled into the mesh part of an expanded lattice made of antimony-free Pb-Ca-Sn alloy, aged and dried to obtain an unformed positive electrode plate with a width E of 100 mm, a height of 110 mm, and a thickness of 1.6 mm. .

(3) Separator After extruding into a sheet a resin composition containing 100 parts by mass of polyethylene, 160 parts by mass of silica particles, 80 parts by mass of paraffin oil as a pore-forming agent, and 2 parts by mass of a penetrating agent, By removing a portion of the pore-forming agent, a microporous membrane was produced in which the pore volume P _t and the pore ratios r1 and r2 determined by the procedure described above had the values shown in Table 1. In extrusion molding, the difference between the thickness of the edge of the separator and the thickness of the main part (Tp - Tm) is the value shown in Table 1, and as shown in Figure 1, a plurality of striped main ribs and mini ribs are formed. A mold having the shape to be formed was used. Next, each sheet-like microporous membrane was folded in half to form a bag, and welded portions were formed at both ends in the first direction D1 to obtain a bag-like separator as shown in FIG. 1. The edges are formed on both end sides in the first direction, the width B of each edge is 20 mm, the width A of the main part is 75 mm, and the width W of the separator in the first direction D1 is 115 mm. Ta.

Note that the composition of the resin composition containing polyethylene, silica particles, a pore-forming agent, and a penetrating agent may be arbitrarily changed depending on the separator design, manufacturing conditions, and/or how the lead-acid battery is used. Further, the Na content in the separator, the amount of penetrating agent, the amount of pore-forming agent removed, etc. are adjusted as necessary.

On the outer surface of the bag-shaped separator, the protruding heights of the main ribs and miniribs were set to 0.6 mm and 0.15 mm, respectively. The pitch of the main ribs was 9.8 mm, and the pitch of the mini ribs was 1 mm. The total thickness of the separator was 0.8 mm. The content of silica particles in the separator was 60% by mass. Note that the total thickness of the separator, the protruding height of the ribs, the pitch of the ribs, and the content of silica particles are the values obtained for the separator before manufacturing the lead-acid battery, but the values for the separator taken out from the lead-acid battery after manufacturing are the same. This value is almost the same as the value measured using the procedure described above.

(4) Production of lead-acid battery Each unformed negative electrode plate was housed in a bag-like separator, and an electrode plate group was formed by seven unformed negative electrode plates and six unformed positive electrode plates per cell. The lugs of the positive electrode plate and the lugs of the negative electrode plate were welded to the positive electrode shelf portion and the negative electrode shelf portion, respectively, using a cast-on strap (COS) method. Insert the electrode plate group into a polypropylene battery case, inject electrolyte, and perform chemical conversion in the battery case to achieve a rated voltage of 12V and a rated capacity of 30Ah (5 hour rate capacity (the value stated in the rated capacity). Liquid lead-acid batteries E1 to E23 and R1 to R7 were assembled, each having a capacity when discharged at a current of 1/5 of Note that six electrode plate groups are connected in series within the battery case.

As the electrolytic solution, an aqueous sulfuric acid solution in which aluminum sulfate was dissolved was used. The specific gravity of the electrolytic solution after chemical formation at 20° C. was 1.285, and the Al ion concentration was 0.2% by mass.

[Evaluation 1: Oil content in separator]
The oil content of the separator taken out from the produced lead-acid battery was determined by the procedure described above.

[Evaluation 2: Puncture strength]
The puncture strength (N) at the edge of the separator was determined by the above-described procedure for the separator taken out from the produced lead-acid battery. For the separator with (Tp-Tm)=0 mm, the puncture strength was determined at the end portion in the first direction corresponding to the edge of the separator where (Tp-Tm)≠0 mm.

[Evaluation 3: CCA performance]
The terminal voltage (V) of each lead-acid battery 30 seconds after the start of discharge was determined using the procedure described above.

[Evaluation 4: IS life performance]
The number of cycles until the terminal voltage of each lead-acid battery reached 7.2 V was determined using the procedure described above.

[Evaluation 5: High temperature overcharge life]
The number of life cycles of each lead-acid battery in a high-temperature overcharge durability test was measured according to the procedure described above.

Table 1 shows the results of evaluations 1 to 5. Evaluations 2 to 5 are expressed as a ratio when the result of lead-acid battery R1 is set to 1. Table 1 also shows the pore volume P _t , pore ratios r1 and r2, and (Tp−Tm).

As shown in Table 1, for lead-acid batteries R1 and R3 with pore volumes P _t <0.8 cm ³ /g, the edge thickness Tp is only 0.05 mm larger than the main portion thickness Tm. It can be seen that the CCA performance has decreased by 20%, and the resistance of the separator has increased. When P _t <0.8 cm ³ /g, even if the pore ratio r1 increases from 45% to 50% or 55%, the CCA performance remains low (comparison of R1 to R3), and r1 Even in the case of 80% (R6), the CCA performance is comparable to R1.

On the other hand, when the pore volume P _t ≧0.8 cm ³ /g and the pore ratio r1≧50%, the CCA Performance is improved by 20% (comparison between R1 and E1). Further, in the case of P _t ≧0.8 cm ³ /g, when the pore ratio r1 increases from 45% to 50% or 55%, the CCA performance improves (comparison of R5, E1 and E2). Furthermore, from a comparison of R6, E1, and E2, high CCA performance is secured even when the pore ratio r1 increases from 50% to 55%, but when it decreases from 50% to 45%, the CCA performance significantly increases. It is declining.

Furthermore, compared to the case of R1 (pore volume P _t =0.7 cm ³ /g, pore ratio r1 = 50%, (Tp-Tm) = 0), R7 (pore volume P _t =0.8 cm ³ /g, pore ratio r1=50%, (Tp-Tm)=0), the CCA performance improved from 1 to 1.2. On _the other ^hand , E1 (pore volume P When _t = 0.8 cm ³ /g, pore ratio r1 = 50%, (Tp-Tm) = 0.05 mm), the CCA performance was greatly improved from 0.8 to 1.2. In this way, when P _t is less than 0.8 cm ³ /g and when it is 0.8 cm ³ /g or more, the pore ratio r1 is set to 50% or more, and the thickness Tp of the edge part is set to 50% or more. The influence (or behavior) of making the thickness larger than Tm on the CCA performance differs greatly. Accordingly, it can be said that the effect of suppressing the decline in CCA performance can only be obtained by setting the pore volume P _t to 0.8 cm ³ /g or more. Therefore, it can be said that Table 1 shows the criticality of setting the pore volume P _t to 0.8 cm ³ /g or more. Furthermore, from Table 1, when the pore volume P _t is 2.0 cm ³ /g or less (preferably 1.9 cm ³ /g or less or 1.8 cm ³ /g or less), high CCA performance and puncture strength can be ensured. , it is possible to suppress the deterioration of IS life performance.

Furthermore, when the oil content in the separator is 10% by mass or more, a superior high-temperature overcharge life is obtained compared to when the oil content is less than 10% by mass (E21 and E1, E22, and E23). comparison). When the oil content is 13% by mass or more, an even higher high temperature overcharge life can be obtained (comparison of E1 with E21 to E23, comparison of E4 with E1 to E3 and E5 to E20). This is because a relatively large amount of oil is retained within the pores of the separator, and the pore structure is optimized, so even if a high-temperature overcharge durability test is performed, oil outflow is suppressed and the separator retains a large amount of oil. This is thought to be because oxidative deterioration was suppressed. Moreover, it is considered that more oil is easily retained because the ratio r2 is 20% or more.

The separator for liquid lead-acid batteries according to the above aspect of the present invention is suitable, for example, for IS applications (lead-acid batteries for ISS vehicles, etc.), starting power supplies for various vehicles (automobiles, motorcycles, etc.), and the like. Furthermore, the separator for liquid lead-acid batteries can be suitably used as a power source for industrial power storage devices such as electric vehicles (forklifts, etc.). Note that these uses are merely examples, and the separator for a liquid lead-acid battery and the liquid lead-acid battery according to the above aspects of the present invention are not limited to these uses.

1: Lead-acid battery, 2: Negative electrode plate, 3: Positive electrode plate, 4,100: Separator, 5: Positive electrode shelf, 6: Negative electrode shelf, 7: Positive electrode column, 8: Through-connection body, 9: Negative electrode column, 11 : Electrode plate group, 12: Battery case, 13: Partition wall, 14: Cell chamber, 15: Lid, 16: Negative electrode terminal, 17: Positive electrode terminal, 18: Liquid port plug, 100A: First part, 100B: Second part , 101: crease, 103: main part, 103b: first base part, 103r: main rib, 105: edge, 105b: second base part, 105r: mini rib, 105s: welded part

Claims (10)

It has a main part and a pair of edges located at both ends of the main part in the first direction,
The thickness Tp of the pair of edge parts is larger than the thickness Tm of the main part,
The total pore volume is 0.8 cm ³ /g or more and 2.0 cm ³ /g or less,
A separator for a liquid lead-acid battery, wherein the ratio r1 of the pore volume of the first pores having a pore diameter of 0.1 μm or more and 10 μm or less to the total pore volume is 50% or more. The separator for a liquid lead acid battery according to claim 1, wherein the ratio r1 of the first pores is 80% or less. The separator for a liquid lead acid battery according to claim 1 or 2, wherein the total pore volume is 1.8 cm ³ /g or less. The separator for a liquid lead-acid battery according to any one of claims 1 to 3, wherein the difference between the thickness Tp of the edge portion and the thickness Tm of the main portion is 0.05 mm or more. The separator for a liquid lead-acid battery according to any one of claims 1 to 4, wherein the main portion has a thickness Tm of 0.15 mm or more and 0.25 mm or less. The separator contains oil,
The separator for a liquid lead-acid battery according to any one of claims 1 to 5, wherein the content of the oil in the separator is 10% by mass or more. The separator includes second pores having a pore diameter of 0.03 μm or less,
The separator for a liquid lead-acid battery according to claim 6, wherein a ratio r2 of the pore volume of the second pores to the total pore volume is 20% or more. A liquid lead-acid battery comprising a positive electrode plate, a negative electrode plate, and the separator according to any one of claims 1 to 7. The liquid lead-acid battery according to claim 8, wherein the width of the positive electrode plate and the width of the negative electrode plate are both larger than the width of the main portion. The liquid lead-acid battery according to claim 8 or 9, which is used for idling stop or for starting a vehicle.

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