JP2021192352A - Lead acid battery - Google Patents

Abstract

SOLUTION: A lead acid battery comprises a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolytic solution. The positive electrode plate includes a positive electrode current collector and a positive electrode material, the negative electrode plate includes a negative electrode current collector and a negative electrode material. At least one of lower corners, which is a pair, of the positive electrode plate is chamfered. The negative electrode material includes a Tl element and a content of the Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm on a mass basis. The negative electrode material includes no Sb element, or, a content of the Sb element in the negative electrode material when the negative electrode material includes the Sb element is 40 ppm or less on a mass basis.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lead storage battery.

Lead-acid batteries are used in various applications such as in-vehicle use and industrial use. The lead-acid battery includes a positive electrode plate and a negative electrode plate, a separator interposed therein, and an electrolytic solution. Various performances are required for the components of lead-acid batteries.

Patent Document 1 describes an expanded portion, a transverse bone portion for forming an ear portion composed of a non-expanded portion formed on one end side in the expanded direction of the expanded portion, and a current collector formed in the transverse bone portion. An expanded lattice having an ear portion is used as a positive electrode current collector and a negative electrode current collector, and the positive electrode current collector and the negative electrode current collector are filled with a positive electrode active material and a negative electrode active material, respectively. In a lead storage battery provided with a positive electrode plate and a negative electrode plate, among the four corners of at least one of the positive electrode plate and the negative electrode plate, the lead storage battery exists on the side opposite to the side where the current collecting ear portion is provided. We propose a lead storage battery in which two corners are cut in a direction inclined with respect to the longitudinal direction of the horizontal bone for forming an ear for collecting electricity, and cuts are formed in each of the two corners. ..

In Patent Document 2, a positive electrode plate using a positive electrode lattice made of a lead-calcium-tin-talium alloy and a negative electrode plate using a negative electrode lattice made of a lead alloy are alternately arranged via a separator, respectively. We are proposing a lead-acid battery equipped with a group of electrode plates in which the electrodes are connected in parallel, and an electric tank for accommodating the group of electrode plates and an electrolytic solution.

According to Patent Document 3, in a lead storage battery, a positive electrode member composed of a positive electrode lattice, a positive electrode shelf, a positive electrode pole column, and a positive electrode connector is made of a lead or a lead alloy that substantially does not contain Sb, and a negative electrode lattice, a negative electrode shelf, and a negative electrode electrode. Of the negative electrode members composed of columns and negative electrode connectors, the parts other than the negative electrode lattice bone are made of lead or lead alloy that does not contain Sb, and either the negative electrode lattice bone or the negative electrode active material contains Sb. The present invention proposes a lead storage battery in which the content of Sb with respect to the amount of the negative electrode active material is 0.001 to 0.1% by mass.

Japanese Unexamined Patent Publication No. 2008-204639 International Publication No. 2015/037172 Japanese Unexamined Patent Publication No. 2003-346888

In a lead-acid battery, sulfate ions having a large specific gravity drop during charging, and stratification is likely to occur in which a difference in specific gravity of the electrolytic solution (that is, a difference in concentration of sulfuric acid) occurs between the upper part and the lower part of the battery case. In a lead-acid battery for general starting, gas is generated by charging to a state close to overcharge or full charge, so that convection of the electrolytic solution occurs due to the stirring effect of the gas, and stratification is suppressed to some extent.

However, when the lead-acid battery is used in a state of insufficient charge called a partially charged state (PSOC), stratification becomes remarkable. For example, in IS applications such as idling start / stop (ISS) vehicles or charge control applications, lead-acid batteries will be used in PSOC. When stratification becomes remarkable, the positive electrode plate deteriorates, and the life performance (also referred to as IS life performance) of the lead storage battery when used in PSOC deteriorates.

When a current collector whose corner opposite to the selvage portion is cut is used as in Patent Document 1, since there is no electrode material in the cut portion, gas generation during charging is unlikely to occur. Therefore, stratification becomes remarkable, and the IS life performance is greatly deteriorated.

One aspect of the present invention is a lead-acid battery.
The lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolytic solution.
The positive electrode plate comprises a positive electrode current collector and a positive electrode material.
The negative electrode plate comprises a negative electrode current collector and a negative electrode material.
At least one of the pair of lower corners of the positive electrode plate is chamfered.
The negative electrode material contains a Tl element and contains.
The content of Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm on a mass basis.
The present invention relates to a lead storage battery in which the negative electrode material does not contain Sb element or contains Sb element, and the content of Sb element in the negative electrode material is 40 ppm or less on a mass basis.

Excellent IS life performance can be ensured in lead-acid batteries.

It is a top view which shows the appearance of the electrode plate used in the lead storage battery which concerns on one Embodiment of this invention. It is a partially cutaway perspective view which shows the appearance and the internal structure of the lead storage battery which concerns on one Embodiment of this invention.

In a lead-acid battery, when discharged, lead sulfate is generated on both the positive electrode plate and the negative electrode plate, and water is generated on the positive electrode plate. On the other hand, during charging, metallic lead, lead dioxide, and sulfuric acid are produced from lead sulfate and water. Since the specific gravity of sulfate ion is large, it easily descends to the lower part of the battery case. When convection of the electrolytic solution is unlikely to occur, a difference in sulfuric acid concentration occurs between the upper part and the lower part of the electric tank, and stratification occurs. In a lead-acid battery for general starting, gas is generated by charging to a state close to overcharge or full charge, so that convection of the electrolytic solution occurs due to the stirring effect of the gas, and stratification is suppressed. On the other hand, when a lead-acid battery is used in PSOC, a sufficient stirring effect cannot be obtained because gas generation during charging is small, and stratification of the electrolytic solution tends to proceed.

If the lead-acid battery is continuously used in the stratified state, the charge / discharge efficiency is lowered due to the low specific gravity of the electrolytic solution at the upper part of the battery case, and the life of the lead storage battery is reached. In addition, the accumulation of lead sulfate in the negative electrode plate becomes remarkable in the lower part of the electric tank where the specific gravity of the electrolytic solution is high, and the sulfation in which lead sulfate is inactivated tends to proceed. As a result, the charge / discharge reaction is concentrated on the upper part of the electrode plate, and the softening and deterioration of the positive electrode electrode material is likely to proceed, and the positive electrode material may fall off from the positive electrode plate and reach the end of its life. For example, when the dropped positive electrode material adheres to the electrode plate while floating in the electrolytic solution and is reduced, it becomes conductive. As the deposition of the positive electrode material progresses, a conductive path is formed between the positive electrode plate and the negative electrode plate via the conductive deposit, and an internal short circuit (referred to as a moss short circuit) occurs. In addition, lead sulfate is easily dissolved in the electrolytic solution at the upper part of the electric tank having a low specific gravity of the electrolytic solution, lead ions generated by the dissolution are reduced by the negative electrode plate, and dendrite-like precipitated lead crystals penetrate the separator. The life may be reached due to a permeation short circuit. As described above, the progress of stratification tends to be a factor that determines the IS life performance of the lead storage battery.

When the electrode plate with the lower corners chamfered is used, the amount of gas generated during charging is small because the electrode material does not exist in the portion cut off by the chamfering of the electrode plate. Therefore, when a lead-acid battery provided with such an electrode plate is used in PSOC, the stratification of the electrolytic solution becomes remarkable. When stratification becomes remarkable, the IS life performance deteriorates as described above.

On the other hand, when a negative electrode material containing Tl of 1 ppm or more and less than 33 ppm on a mass basis is used, the generation of hydrogen gas during charging is promoted, and the electrolytic solution is easily convected. This reduces stratification to some extent. However, since the electrolytic solution is easily convected, the fallen positive electrode material is likely to float, and a moss short circuit is likely to occur. As a result, the moss short circuit leads to the life of the lead-acid battery.

However, in a lead-acid battery, it is clear that the IS life performance is unexpectedly greatly improved by combining a negative electrode material containing Tl of 1 ppm or more and less than 33 ppm on a mass basis with a positive electrode plate having a chamfered lower corner. It became.

In view of such findings, the lead-acid battery according to one aspect of the present invention includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolytic solution. The positive electrode plate includes a positive electrode current collector and a positive electrode material. The negative electrode plate includes a negative electrode current collector and a negative electrode material. At least one of the pair of lower corners of the positive electrode plate is chamfered. The negative electrode material contains Tl element, and the content of Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm on a mass basis. When the negative electrode material does not contain Sb element or contains Sb element, the content of Sb element in the negative electrode electrode material is 40 ppm or less on a mass basis.

By using a negative electrode material containing Tl element with a content of 1 ppm or more and less than 33 ppm on a mass basis, the amount of gas generated during charging can be appropriately increased even when a lead-acid battery is used in PSOC. By increasing the amount of gas generated, convection of the electrolytic solution is promoted, and stratification can be suppressed. Therefore, even when a positive electrode plate having a chamfered lower corner is used, the electrolytic solution can be convected to suppress stratification.

When a positive electrode plate having a chamfered lower corner is used, a space is formed in the bottom of the battery case of the lead storage battery, which is cut off by chamfering the lower corner of the positive electrode plate. Even if a lead storage battery is used in PSOC and the positive electrode material is dropped, the dropped positive electrode material is collected in the above space formed at the bottom of the battery case. Since the charge / discharge reaction hardly occurs in this space and the amount of gas generated is small, the floating of the collected positive electrode material is reduced. This reduces the accumulation of the dropped positive electrode material on the electrode plate. Therefore, by using a negative electrode material containing Tl element with a content of 1 ppm or more and less than 33 ppm on a mass basis, even if the electrolytic solution is easily convected, the dropped positive electrode material is contained in the above space. By keeping it and suppressing floating, it is possible to suppress the occurrence of moss short circuit.

Furthermore, by setting the mass-based content of the Sb element in the negative electrode material to 40 ppm or less, self-discharge based on the potential difference between Pb and Sb can be reduced, and even if charging and discharging are repeated with PSOC, the capacity can be reduced. It is possible to prevent the shortage.

As described above, in the lead-acid battery according to the above aspect of the present invention, stratification and the occurrence of moss short circuit are suppressed even when used in PSOC. Therefore, an excellent IS life can be ensured. Further, if the corner portion of the positive electrode plate is deformed in the manufacturing process of the positive electrode plate, the separator is breached at the initial stage of the lead storage battery, and a short circuit is likely to occur. In the lead-acid battery according to the above side surface, by using a positive electrode plate having a chamfered lower corner portion, it is possible to reduce the occurrence of an initial short circuit due to such deformation of the corner portion.

Even if the negative electrode material as described above is used in combination with a plate whose lower corners are not chamfered, the IS life performance is deteriorated. It is considered that this is because the moss short circuit cannot be suppressed. That is, it can be said that the effect of using the negative electrode material as described above is the effect obtained only in combination with the positive electrode plate in which the lower corner is chamfered.

Of the positive electrode plate and the negative electrode plate, at least one of the pair of corners may be chamfered at least in the lower part of the positive electrode plate, and even if at least one of the pair of corners is chamfered in the lower part of the negative electrode plate. good. Above all, it is preferable that at least one of the pair of corners is chamfered in the lower part of the positive electrode plate, and the pair of corners is not chamfered in the lower part of the negative electrode plate. By not chamfering both of the pair of lower corners of the lead-acid battery of the negative electrode plate, the negative electrode plate has a portion that does not face the positive electrode plate (hereinafter referred to as a non-opposed portion) in the lower corner portion. .. This non-opposing portion is unlikely to contribute to the charge / discharge reaction, and a reaction in which hydrogen gas is generated by applying a voltage can mainly occur. Therefore, by providing the non-opposing portion on the negative electrode plate, hydrogen gas is generated even in PSOC, although it is small, and convection of the electrolytic solution is likely to occur. As a result, the effect of suppressing stratification is further enhanced, and the IS life performance can be further enhanced. The amount of hydrogen gas generated in the non-opposing portion is relatively small. Therefore, in the lower corner of the positive electrode plate, the fallen positive electrode electrode material contained in the space formed in the portion where the positive electrode plate is cut off is insufficient to float. Therefore, even if the effect of convection of the electrolytic solution is slightly improved, the occurrence of moss short circuit can be suppressed.

The current collector of the positive electrode plate is preferably an expanded grid. In the process of manufacturing the positive electrode plate, the corners may be deformed due to interference with the manufacturing equipment. Since the expanded lattice used for the positive electrode plate has a thick lattice bone, it is difficult to return to the original shape once the corner portion of the positive electrode plate using the expanded lattice is deformed. Therefore, when a lead-acid battery is manufactured using such a positive electrode plate, a corner portion of the positive electrode plate breaks through the separator at an initial stage, and a short circuit is likely to occur. Therefore, in the case of a positive electrode plate using an expanded lattice, since the corners of the positive electrode plate are chamfered, it is possible to suppress an initial short circuit due to deformation of the corners of the positive electrode plate, which is advantageous.

The separator comprises a polyolefin, which preferably contains at least ethylene units. Polyolefins containing ethylene units as monomer units are prone to oxidative deterioration. However, even when a separator containing a polyolefin that is easily oxidatively deteriorated is used, the separator is oxidized by reducing the deposition of the positive electrode material on the electrode plate by combining with the positive electrode plate whose lower corner is chamfered. Since deterioration can be suppressed, excellent IS life performance can be ensured.

The separator is bag-shaped and preferably accommodates a negative electrode plate. In this case, it is possible to prevent the positive electrode plate and the negative electrode plate from being short-circuited via the positive electrode material settled in the vicinity of the corner portion of the positive electrode plate.

The separator preferably contains oil. When the separator contains oil, the effect of suppressing oxidative deterioration of the separator can be further enhanced, so that higher IS life performance can be ensured.

The oil content in the separator is preferably 12% by mass or more and 18% by mass or less. When the oil content is in such a range, the effect of suppressing oxidative deterioration is further enhanced, and the resistance of the separator can be further reduced. Therefore, higher IS life performance can be ensured.

The lead storage battery may be a control valve type battery (VRLA type battery), but a liquid type battery (vent type battery) is preferable. In a liquid battery, the problem due to the deposition of the stratified and shed positive electrode material on the electrode plate tends to become remarkable. In such a liquid battery, stratification and moss short circuit are achieved by combining a negative electrode material having a specific mass-based content of Tl and Sb as described above and a positive electrode plate having chamfered corners. The suppressive effect of is remarkably exhibited.

(Explanation of terms)
(Vertical direction of lead-acid battery or lead-acid battery component)
In the present specification, the vertical direction of the lead-acid battery or the component of the lead-acid battery (plate, battery case, separator, etc.) means the vertical direction of the lead-acid battery in the state where the lead-acid battery is used. The upper part of the lead-acid battery means the part above half the height of the lead-acid battery in the state where the lead-acid battery is used. The lower part of the lead-acid battery means a part other than the upper part of the lead-acid battery. The upper part of each component of the lead-acid battery means the part above half the height of each component in the state where the lead-acid battery is used. The lower part of each component means a part other than the upper part of each component. The positive electrode plate and each electrode plate of the negative electrode plate are provided with an ear portion for connecting to an external terminal, and in a liquid battery, the ear portion is provided so as to project upward above the electrode plate. There is. The height of each electrode plate shall mean the height of the portion where the electrode material is present.

(Corner of the electrode plate)
When viewed from the front, a general electrode plate has a substantially quadrangular shape except for the ears, and has four corners including corners. In the state where a lead-acid battery is used, the four corners of the electrode plate are composed of a pair of corners located at the upper part and a pair of corners located at the lower part. In the present specification, each corner portion of the electrode plate (or a portion corresponding to the corner portion if the corner portion is missing) and the entire portion including the periphery thereof are referred to as a corner portion. In each of the positive electrode plates and the negative electrode plates of the lead storage battery according to the above aspect of the present invention, the chamfered corners are at least one of the pair of corners located at the lower part of each electrode plate. The state in which the electrode plate is viewed from the front means a state in which each of the pair of main surfaces (that is, the pair of surfaces excluding the end faces) occupying most of the surface of the electrode plate is viewed from a vertical direction.

(chamfer)
In the lead-acid battery according to the above aspect of the present invention, at least one of the pair of lower corners is chamfered in at least the positive electrode plate (and further, the negative electrode plate if necessary). The state in which the corners are chamfered means a state in which the corners and peripheral portions normally possessed by the electrode plate are cut off. In other words, in the chamfered corners, a portion where the electrode plate (more specifically, the corner portion of the electrode plate and its peripheral portion) is cut off (hereinafter, may be referred to as a cut-off portion) is formed. Has been done. This cutout portion creates a space at the bottom of the battery case.

More specifically, in the state where the corners are chamfered in each corner of the lower part, the area of the missing part in each corner of the lower part when the electrode plate is viewed from the front is S1 and S2. When the area S1 or S2 occupies the total area S (= S1 + S2) of the area A of the electrode plate and the total area S (= S1 + S2) of the lower portion r (= S1 / (A + S) × 100 (%) or S2 / (A + S). ) × 100 (%)) is 0.1% or more. For one corner of the lower part, the state where the lower corner part is not chamfered includes the case where the ratio r is less than 0.1%.

The area A of the electrode plate is a projected area when a portion of the electrode plate in which the electrode material is present is projected in a direction perpendicular to one main surface of the electrode plate. Further, the areas S1 and S2 of the cutout portion in each corner of the lower portion of the electrode plate have the upper and bottom sides of the portion where the electrode material is present in the extending direction (that is, that is, when the electrode plate is viewed from the front. The two straight lines extending in the horizontal direction (also referred to as the first direction) and the sides located on both sides of the portion where the electrode material exists are in the respective extending directions (that is, the vertical direction (also referred to as the second direction)). ) Is the area of the portion where the electrode plate is missing at each corner when compared with the rectangle formed by the two straight lines (hereinafter, also referred to as the rectangle A). If a region where the electrode material does not exist is partially formed in the vicinity of each of the upper end portion, the lower end portion, and the side end portion of the portion where the electrode material exists, the region where the electrode material does not exist is ignored. , The bottom, the top, and the sides located on the sides shall be determined.

The fact that the corners are chamfered does not necessarily mean that the step of removing the corners and the peripheral portions of the electrode plate is performed, and the corners and the peripheral portions are not removed without removing the corners and the peripheral portions. In some cases, a plate is formed with the peripheral portion removed. In a state where the corners are chamfered, a surface may be formed in the corners by cutting off the corners and their peripheral portions, but the surfaces do not necessarily have to be formed. The chamfered corner includes, for example, a rounded corner and its periphery, and a diagonally cut corner and its periphery. The chamfer may be, for example, C chamfer or R chamfer.

(Electrode material)
In each electrode plate of the positive electrode plate and the negative electrode plate, the electrode material is usually held by a current collector. The electrode material is a plate from which the current collector is removed. Members such as mats and pacing papers may be attached to the electrode plate. Since such a member (also referred to as a sticking member) is used integrally with the plate, it is included in the plate. When the electrode plate includes a sticking member, the electrode material excludes the current collector and the sticking member. In the present specification, the electrode material of the positive electrode plate may be referred to as a positive electrode material, and the electrode material of the negative electrode plate may be referred to as a negative electrode material.

(Polyolefin)
The polyolefin is a polymer containing at least an olefin unit (that is, a polymer containing at least a monomer unit derived from an olefin). Polyolefins include, for example, homopolymers of olefins, copolymers containing different olefin units, copolymers containing olefin units and copolymerizable monomer units. The copolymer containing an olefin unit and a copolymerizable monomer unit may contain one or more olefin units. Further, the copolymer containing the olefin unit and the copolymerizable monomer unit may contain one kind or two or more kinds of copolymerizable monomer units. The copolymerizable monomer unit is a monomer unit derived from a polymerizable monomer other than the olefin and copolymerizable with the olefin.

(oil)
Oil refers to a hydrophobic substance that is liquid at room temperature (temperature of 20 ° C. or higher and 35 ° C. or lower) and separates from water. Oils include naturally occurring oils, mineral oils, and synthetic oils.

(Fully charged)
In the present specification, the fully charged state of the lead-acid battery is defined by the definition of JIS D 5301: 2019. More specifically, the terminal during charging in which the lead-acid battery was measured every 15 minutes in a water tank at 25 ° C. ± 2 ° C. with a current (A) of 1/10 of the value described as the rated capacity (Ah). A fully charged state is defined as a state in which the electrolytic solution density converted into a voltage or a temperature of 20 ° C. is charged three times in a row until it shows a constant value with three significant digits. Charging is performed in a state where the electrolytic solution of the lead storage battery is filled to a specified liquid level. The numerical value described as the rated capacity is a numerical value in which the unit is Ah. The unit of current set based on the numerical value described as the rated capacity is A.

A fully charged lead-acid battery is a fully charged lead-acid battery. The lead-acid battery may be fully charged after the chemical conversion, immediately after the chemical conversion, or after a lapse of time from the chemical conversion (for example, after the chemical conversion, the lead-acid battery in use (preferably at the initial stage of use) is fully charged. May be).

In the present specification, the battery at the initial stage of use means a battery that has not been used for a long time and has hardly deteriorated.

Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described more specifically with reference to the drawings. However, the present invention is not limited to the following embodiments.

(Positive plate)
As the positive electrode plate, a paste type positive electrode plate is used. The paste-type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held in the positive current collector.

The positive 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 the processing method include expanding processing and punching processing. It is preferable to use a grid-shaped current collector as the positive electrode current collector because it is easy to support the positive electrode material. When a positive electrode current collector (in other words, an expanded grid) obtained by the expand processing is used, a short circuit is likely to occur in the initial lead-acid battery due to deformation of the corners. However, since the lower corner of the positive electrode plate is chamfered, even when such an expanded grid is used, it is possible to suppress an initial short circuit while ensuring excellent IS life performance.

As the lead alloy used for the positive electrode current collector, Pb-Ca-based alloys and Pb-Ca-Sn-based alloys are preferable in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have lead alloy layers having different compositions, and the alloy layer may be one layer or a plurality of layers.

At least one of the pair of corners at the bottom of the positive electrode plate is chamfered. As a result, a portion (removed portion) in which the positive electrode plate is cut off is formed in the corner portion. Of the pair of corners at the bottom of the positive electrode plate, at least one may be chamfered, and both may be chamfered.

When the positive electrode plate is viewed from the front, the ratio R1 of the total area S (= S1 + S2) of the missing portion in the lower corner to the total area A of the positive electrode plate and the total area S of the missing portion is, for example, 0.1% or more or 0.5% or more. The ratio R1 is preferably 1% or more, more preferably 2% or more, from the viewpoint of easily securing a sufficient space for accommodating the dropped positive electrode material even when charging and discharging are repeated for a long period of time. From the viewpoint of ensuring a higher capacity, the ratio R1 of the missing portion is preferably 6% or less, more preferably 4% or less.

The ratio R1 of the missing part is 0.1% or more and 6% or less (or 4% or less), 0.5% or more and 6% or less (or 4% or less), 1% or more and 6% or less (or 4% or less). , Or 2% or more and 6% or less (or 4% or less).

The area A is obtained by binarizing the portion where the electrode material is present and the other region in the photograph of one of the main surfaces of the electrode plate and calculating the area of the portion where the electrode material is present.

Each of the areas S1 and S2 of the missing portion in the lower corner is obtained by the following procedure with reference to FIG. 1 described later. In the example of FIG. 1, the missing portion is formed in both corners of the lower portion of the electrode plate and is indicated by X1 and X2.
The part of the plate excluding the ears has an almost rectangular shape (rectangular or square) when the plate is viewed from the front. The contour of the projected shape of the plate is parallel to the straight line portion L1 extending parallel to the first direction (horizontal direction), which is the extending direction of the bottom of the plate, and the second direction (vertical direction) intersecting the first direction. It has a straight line portion L2 extending to, and the straight line portions L1 and L2 are connected via a connecting portion C. The shape of the connecting portion C is not particularly limited, but may include, for example, at least one selected from the group consisting of a curved line and straight lines inclined from the first direction and the second direction.

Consider an extension line E1 in which the straight line portion L1 is extended to the L2 side and an extension line E2 in which the straight line portion L2 is extended to the L1 side. Each of the areas S1 and S2 of the missing portion is obtained by calculating the area of the region surrounded by the extension line E1, the extension line E2, and the connection portion C.

The ratio R1 of the total area S (= S1 + S2) of the missing portion is calculated by the following formula (1).
R1 = S / (A + S) (1)
As the total (= A + S) of the area A of the electrode plate and the total area S of the missing portion, the area of the rectangle A described above is used. The area of the rectangle A is the product of the height H and the width W of the rectangle A.

The total area S of the cutout portion in the lower part of the positive electrode plate is, for example, 1 cm ² or more, and ^{may be 2 cm 2} or more. The total area S is, for example, 7 cm ² or less, and ^{may be 4.5 cm 2} or less.

The total area S may be 1 cm ² or more (or 2 cm ² or more) 7 cm ² or less, or 1 cm ² or more (or 2 cm ² or more) 4.5 cm ² or less.

When both of the pair of corners at the bottom of the positive electrode plate are chamfered, the areas S1 and S2 of the cutout portions formed in each corner may be the same or different. Further, the shape of the cutout portion formed in each corner when viewed from the front of the electrode plate may be the same or different.

The positive electrode plate in a state where the lower corners are chamfered may be produced by preparing an unchemical or chemicalized positive electrode plate and then removing the lower corners. For the positive electrode plate with the lower corners chamfered, a positive electrode current collector with at least one of the pair of corners chamfered is used in the portion corresponding to the lower part of the positive electrode plate of the positive electrode current collector. May be produced. The positive electrode current collector with the corners chamfered may be formed by chamfering the corners and peripheral portions of the positive electrode current collector manufactured with the corners present at each corner. Further, when the positive electrode current collector is manufactured, the corners in a chamfered state may be formed. For example, when the positive electrode current collector is formed by punching, the corners are chamfered. When a positive electrode current collector is formed by casting, a positive electrode current collector with chamfered corners is formed by casting using a mold having a chamfered corner.

The positive electrode material contained in the positive electrode plate contains a positive electrode active material (lead dioxide or lead sulfate) whose capacity is developed by a redox reaction. The positive electrode material may contain other additives (reinforcing material, etc.), if necessary.

Examples of the reinforcing material of the additive include fibers (inorganic fibers, organic fibers, etc.). Examples of the resin (or polymer) constituting the organic fiber include acrylic resin, polyolefin resin (polypropylene resin, polyethylene resin, etc.), and polyester resin (including polyalkylene allylate (polyethylene terephthalate, etc.)). , And at least one selected from the group consisting of celluloses (cellulose, cellulose derivatives (cellulose ether, cellulose ester, etc.), etc.). Cellulose also includes rayon.

The amount of the reinforcing material in the positive electrode material is, for example, 0.03% by mass or more. Further, the amount of the reinforcing material in the positive electrode electrode material is, for example, 0.5% by mass or less.

The amount of the reinforcing material in the positive electrode material can be determined by the following procedure. The analysis of the reinforcing material is performed using the positive electrode material collected from the positive electrode plate taken out from the fully charged lead-acid battery.

The positive electrode material is recovered from the positive electrode plate by the following procedure. First, the lead storage battery in a fully charged state is disassembled, and the obtained positive electrode plate is washed with water for 3 to 4 hours to remove the electrolytic solution in the positive electrode plate. The positive electrode plate washed with water is dried in a constant temperature bath at 60 ° C. ± 5 ° C. for 5 hours or more. If the positive electrode plate contains a sticking member after drying, the sticking member is removed from the positive electrode plate by peeling. By collecting the positive electrode material from the vicinity of the center of the top, bottom, left and right when the positive electrode plate is viewed from the front, a positive electrode material for analysis (hereinafter referred to as sample A) can be obtained. Sample A is pulverized as necessary and used for analysis.

The crushed sample A is taken and weighed accurately. Next, sample A is added to a mixed solution of an aqueous nitric acid solution (concentration: 25% by mass) and an aqueous tartrate acid solution (concentration: 500 g / L) (mixing ratio (volume ratio) of the aqueous nitrate solution and the aqueous tartrate acid solution = 7: 2). Dissolve the solubles while stirring under heating. The resulting mixture is filtered using a membrane filter (average pore size: 0.45 μm or less). As a result, the reinforcing material contained in the positive electrode electrode material is obtained as a solid substance on the filter paper. The obtained solid is washed with water and dried. Measure the mass of the dry matter. The ratio (percentage) of the mass of the dried product to the mass of the sample A is obtained. This ratio corresponds to the amount of reinforcing material in the positive electrode material.

The unchemical paste type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging and drying. The positive electrode paste is prepared by adding water and sulfuric acid to lead powder, an antimony compound, and if necessary, other additives (reinforcing material, etc.) and kneading.

A positive electrode plate can be obtained by forming an unchemical positive electrode plate. The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical positive electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, the chemical formation may be performed before assembling the lead-acid battery or the electrode plate group.

(Negative electrode plate)
The negative electrode plate of a lead storage battery is composed of a negative electrode current collector and a negative electrode material. The negative electrode current collector can be formed in the same manner as in the case of the positive electrode current collector.

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

At least one of the pair of corners at the bottom of the negative electrode plate may be chamfered. When the corner portion is chamfered, a portion (removed portion) in which the negative electrode plate is cut off is formed in the corner portion. Both lower corners of the negative electrode plate may not be chamfered.

When the corners of the negative electrode plate are chamfered, the total area S in the lower corners of the negative electrode plate obtained according to the case of the positive electrode plate is the total area A of the negative electrode plate and the total area S of the missing portion. The ratio R1 to the positive electrode may be selected from the range described for the positive electrode.

When both of the pair of corners at the bottom of the negative electrode plate are chamfered, the areas S1 and S2 of the cutout portions formed in each corner may be the same or different. Further, the shape of the cutout portion formed in each corner when viewed from the front of the electrode plate may be the same or different.

The areas S1 of the notched portions facing each other between the positive electrode plate and the negative electrode plate facing each other may be the same or different. Further, the areas S2 of the opposing cutout portions may be the same or different from each other. The shapes of the opposing cutout portions may be the same or different.

If the cut-off portion is not formed in the lower corner of the negative electrode plate, or if the area of the cut-off portion is smaller than the area of the cut-off portion in the corner of the positive electrode plate facing the negative electrode plate, the non-cutting portion does not face the positive electrode plate. Opposing portions are formed. When the negative electrode plate has such a non-opposing portion in the lower corner, the amount of hydrogen gas generated increases, and convection of the electrolytic solution is likely to occur, so that stratification is suppressed. Therefore, it is even more advantageous.

When the positive electrode plate is stacked on the negative electrode plate and viewed from the front of the positive electrode plate, the total area S0 of the non-opposing portion in the lower corner of the negative electrode plate is the area A of the negative electrode plate and the total area of the missing portion. The ratio R2 in the total of S (= S1 + S2) is, for example, 0.1% or more or 0.5% or more. From the viewpoint of further enhancing the diffusion effect of the electrolytic solution, the ratio R2 is preferably 1% or more, more preferably 2% or more. From the viewpoint of enhancing the effect of suppressing the floating of the settled positive electrode material, the ratio R2 of the non-opposing portion is preferably 6% or less, more preferably 4% or less.

The ratio R2 of the non-opposing portion is 0.1% or more and 6% or less (or 4% or less), 0.5% or more and 6% or less (or 4% or less), 1% or more and 6% or less (or 4% or less). , Or 2% or more and 6% or less (or 4% or less).

The ratio R2 of the total area S0 of the non-opposing portion is calculated by the following equation (2).
R2 = S0 / (A + S) (2)
As the total (= A + S) of the area A of the electrode plate and the total area S of the missing portion, the area of the rectangle A described above is used. The area of the rectangle A is the product of the height H and the width W of the rectangle A. The area A and the total area S can be obtained according to the case of the positive electrode plate.

The total area S0 of the non-opposing portion is the non-opposing portion of the positive electrode plate and the negative electrode plate facing each other at each corner of the lower portion of the negative electrode plate when the positive electrode plate is overlapped on the negative electrode plate and viewed from the front of the positive electrode plate. It is the total projected area of the part. The total area S0 is obtained by binarizing the non-opposed portion and the other portion in a photograph taken from the front of the positive electrode plate in a state where the positive electrode plate is overlapped on the negative electrode plate with respect to the facing positive electrode plate and the negative electrode plate. However, it is obtained by finding and summing each area of the non-opposing portions in each corner.

The total area S0 of the non-opposing portion in the lower corner of the negative electrode plate is, for example, 1 cm ² or more, and ^{may be 2 cm 2} or more. The total area S0 is, for example, 7 cm ² or less, and ^{may be 4.5 cm 2} or less.

The total area S0 may be 1 cm ² or more (or 2 cm ² or more) 7 cm ² or less, or 1 cm ² or more (or 2 cm ² or more) 4.5 cm ² or less.

The negative electrode plate with the lower corners chamfered can be manufactured in the same manner as in the case of the positive electrode plate.

The negative electrode material contains a negative electrode active material (lead or lead sulfate) that develops a capacity by a redox reaction. The negative electrode material contains a Tl element. The negative electrode material may contain Sb element. Further, the negative electrode electrode material may contain an organic shrinkage proofing agent, a carbonaceous material, barium sulfate and the like. The negative electrode material may contain other additives (reinforcing material, etc.), if necessary.

The content of Tl element in the negative electrode material is 1 ppm or more on a mass basis. When the mass-based content of the Tl element is less than 1 ppm, the effect of suppressing stratification is low, and it is difficult to secure a sufficient effect of improving the IS life performance. From the viewpoint that a higher inhibitory effect on stratification can be easily obtained, the mass-based content of the Tl element in the negative electrode electrode material is preferably 2.5 ppm or more or 3 ppm or more, and may be 8 ppm or more or 9 ppm or more. .. The mass-based content of Tl element in the negative electrode material is less than 33 ppm. When the mass-based content of the Tl element is 33 ppm or more, the charge amount in the negative electrode plate increases remarkably, which causes the corrosion of the positive electrode current collector during charging to progress and the IS life performance to deteriorate. .. From the viewpoint of suppressing the progress of corrosion of the positive electrode current collector and obtaining higher IS life performance, the mass-based content of Tl element in the negative electrode electrode material is preferably 31 ppm or less, preferably 30 ppm or less. Is more preferable.

The content of Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm (or 31 ppm or less), 2.5 ppm or more and less than 33 ppm (or 31 ppm or less), 3 ppm or more and less than 33 ppm (or 31 ppm or less), 8 ppm or more on a mass basis. It may be less than 33 ppm (or 31 ppm or less), 9 ppm or more and less than 33 ppm (or 31 ppm or less), 1 ppm or more (or 2.5 ppm or more) 30 ppm or less, 3 ppm or more (or 8 ppm or more) 30 ppm or less, or 9 ppm or more and 30 ppm or less. ..

The content of the Sb element in the negative electrode electrode material is 40 ppm or less based on the mass, and may be 35 ppm or less. When the content of the Sb element is larger than 40 ppm, the self-discharge becomes large. As a result, the IS life performance is reduced.

Examples of the organic shrinkage proofing agent include lignin, lignin sulfonic acid or a salt thereof, a synthetic organic shrinkage proofing agent (formaldehyde condensate of a phenol compound, etc.) and the like. The negative electrode electrode material may contain one kind of organic shrinkage proofing agent, or may contain two or more kinds.

The content of the organic shrinkage barrier in the negative electrode electrode material is, for example, 0.01% by mass or more. The content of the organic shrinkage proofing agent is, for example, 1% by mass or less.

Examples of carbonaceous materials include carbon black, graphite (artificial graphite, natural graphite, etc.), hard carbon, soft carbon, and the like. The negative electrode material may contain one kind of carbonaceous material, or may contain two or more kinds of carbonaceous material.

The content of the carbonaceous material in the negative electrode electrode material is, for example, 0.1% by mass or more. The content of the carbonaceous material may be, for example, 3% by mass or less.

The content of barium sulfate in the negative electrode electrode material is, for example, 0.1% by mass or more. The content of barium sulfate is, for example, 3% by mass or less.

Examples of the reinforcing material include fibers (inorganic fibers, organic fibers (organic fibers composed of the resin described for the reinforcing material of the positive electrode electrode material, etc.)).

The amount of the reinforcing material in the negative electrode electrode material is, for example, 0.03% by mass or more. The amount of the reinforcing material in the negative electrode electrode material is, for example, 0.5% by mass or less.

The negative electrode active material in the charged state is spongy lead, but the unchemical negative electrode plate is usually produced by 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 to produce an unchemical negative electrode plate, and then forming an unchemical negative electrode plate. The negative electrode paste is prepared by adding water and sulfuric acid to lead powder, an organic shrink-proofing agent and, if necessary, various additives, and kneading them. The negative electrode plate in which the negative electrode material contains a Tl element can be formed, for example, by using a Tl compound (oxide, salt, etc.) as an additive. The negative electrode plate in which the negative electrode material contains the Sb element can be formed, for example, by using an Sb compound (oxide, salt, etc.) as an additive.

In the aging step, it is preferable to ripen the unchemical negative electrode plate at a temperature higher than room temperature and high humidity.

The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical negative electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, the chemical formation may be performed before assembling the lead-acid battery or the electrode plate group. The formation produces spongy lead.

(Analysis of negative electrode material or its constituents)
Hereinafter, a method for quantifying an organic shrinkage proofing agent, a carbonaceous material, barium sulfate, a reinforcing material, a Tl element and an Sb element in the negative electrode electrode material will be described. Quantitative analysis of the constituent components of the negative electrode material is performed using the negative electrode material collected from the negative electrode plate taken out from the fully charged lead-acid battery.

The negative electrode material is recovered from the negative electrode plate by the following procedure. First, a fully charged lead-acid battery is disassembled to obtain a negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. Wash with water by pressing the pH test paper against the surface of the negative electrode plate washed with water until it is confirmed that the color of the test paper does not change. However, the time for washing with water shall be within 2 hours. The negative electrode plate washed with water is dried at 60 ± 5 ° C. for about 6 hours under a reduced pressure environment. If the negative electrode plate contains a sticking member after drying, the sticking member is removed from the negative electrode plate by peeling. Next, a sample (hereinafter referred to as sample B) is obtained by separating the negative electrode material from the negative electrode plate. Sample B is crushed as needed and subjected to analysis.

<< Quantification of organic shrinkage proofing agent, Tl element and Sb element >>
The crushed sample B is immersed in a 1 mol / L NaOH aqueous solution to extract an organic shrinkage proofing agent. The insoluble component is removed by filtration from the extracted NaOH aqueous solution containing the organic shrinkage proofing agent, and the filtrate (hereinafter, also referred to as filtrate C) is recovered.

A predetermined amount of the filtrate C is measured, diluted with ion-exchanged water as necessary, and the volume is adjusted. The filtrate or diluted filtrate is used as a solution for quantification of element Tl and element Sb. Inductively coupled plasma (ICP) emission spectroscopy measures the emission intensity of each of the Ti and Sb elements in a solution. Then, the masses of the Tl element and the Sb element contained in the solution are obtained using the calibration curve prepared in advance. From the respective masses of the obtained Tl element and Sb element and the measured amount of the filtrate C, the ratio of each of the Tl element and the Sb element to the mass of the sample B subjected to the analysis was determined in the negative electrode electrode material. It is determined as the content of each of the Tl element and the Sb element. Analysis by ICP emission spectroscopy is performed using SPECTRO-ARCOS manufactured by Hitachi High-Tech Science Corporation.

A predetermined amount of the filtrate C is measured, desalted, concentrated, and dried to obtain a powder of an organic shrinkage proofing agent (hereinafter, also referred to as sample D). Desalting is performed using a desalting column, by passing the filtrate C through an ion exchange membrane, or by placing the filtrate C in a dialysis tube and immersing it in distilled water.

It constitutes an infrared spectroscopic spectrum of sample D, an ultraviolet-visible absorption spectrum of a solution obtained by dissolving sample D in distilled water or the like, an NMR spectrum of a solution obtained by dissolving sample D in a solvent such as heavy water, or a substance. The organic shrink-proofing agent is specified by combining the information obtained from the thermal decomposition GC-MS or the like which can obtain the information of the individual compounds.

The ultraviolet-visible absorption spectrum of the filtrate C is measured. The content of the organic shrinkage barrier in the negative electrode electrode material is quantified from the spectral intensity, the calibration curve prepared in advance, the measured amount of the filtrate C, and the mass of the sample B. If the structural formula of the organic shrinkage proofing agent to be analyzed cannot be specified exactly and the calibration curve of the same organic shrinkage proofing agent cannot be used, an ultraviolet-visible absorption spectrum or an infrared spectroscopic spectrum similar to that of the organic shrinkage proofing agent to be analyzed, A calibration curve is prepared using an available organic shrink-proofing agent showing an NMR spectrum or the like.

<< Quantification of carbonaceous materials, barium sulfate, and reinforcing materials >>
To 10 g of the crushed sample B, 50 mL of nitric acid having a concentration of 20% by mass is added and heated for about 20 minutes to dissolve the lead component as lead ions. Next, the obtained solution is filtered to separate solids such as carbonaceous material and barium sulfate.

The obtained solid content is dispersed in water to form a dispersion liquid, and then the reinforcing material is recovered from the dispersion liquid using a sieve. The reinforcing material is washed with water and dried, and the mass is measured. The ratio (percentage) of the mass of the dried product to the mass of the sample B is obtained. This ratio corresponds to the amount of reinforcing material in the negative electrode material.

After removing the reinforcing material, the dispersion liquid is suction-filtered using a membrane filter whose mass has been measured in advance, and the membrane filter is dried together with the filtered sample in a dryer at 110 ° C. ± 5 ° C. The obtained sample is a mixed sample of a carbonaceous material and barium sulfate (hereinafter, also referred to as sample E). _{The mass of the sample E (M m} ) is measured by subtracting the mass of the membrane filter from the total mass of the sample E and the membrane filter after drying. Then, the dried sample E is put into a crucible together with a membrane filter and incinerated at 700 ° C. or higher. The remaining residue is barium oxide. The mass of the barium oxide is converted to the mass of the barium sulfate determining the mass of barium sulfate (M _B). Calculating the mass of the carbonaceous material from the mass M _m by subtracting the mass M _B.

(Separator)
The separator may be in the form of a sheet. Further, a sheet bent in a bellows shape may be used as a separator. The separator may be formed in a bag shape, or either a positive electrode plate or a negative electrode plate may be wrapped in a bag-shaped separator. From the viewpoint of easily suppressing a short circuit between the positive electrode plate and the negative electrode plate via the sedimented positive electrode material, it is preferable to accommodate the negative electrode plate with a bag-shaped separator.

The separator is formed by extruding a resin composition containing, for example, a polymer material (hereinafter, also referred to as a base polymer), a pore-forming agent, and a penetrant (surfactant) into a sheet, and then removing the pore-forming agent. Obtained by doing. By removing at least a part of the pore-forming agent, micropores are formed in the matrix of the base polymer. The resin composition may further contain inorganic particles. The sheet-shaped separator may be bent into a bellows shape or processed into a bag shape, if necessary.

At least polyolefin is used as the base polymer contained in the separator. As the base polymer, polyolefin and other base polymers may be used in combination. The other base polymer is not particularly limited as long as it is used as a separator for a lead storage battery. The ratio of the polyolefin to the total base polymer contained in the separator is, for example, 50% by mass or more, 80% by mass or more, or 90% by mass or more. The proportion of polyolefin is, for example, 100% by mass or less. The base polymer may be composed only of polyolefin.

Examples of the polyolefin _{include polymers containing at least C2-3} olefin as a monomer unit. Examples of the _C2-3 olefin include at least one selected from the group consisting of ethylene and propylene. As the polyolefin, for example, a _{copolymer containing polyethylene, polypropylene, or C2-3} olefin as a monomer unit (for example, an ethylene-propylene copolymer) is more preferable. Among the polyolefins, it is preferable to use a polyolefin containing at least an ethylene unit (polyethylene, ethylene-propylene copolymer, etc.). Polyolefins containing ethylene units (polyethylene, ethylene-propylene copolymer, etc.) may be used in combination with other polyolefins.

As the inorganic particles, for example, ceramic particles are preferable. Examples of the ceramics constituting the ceramic particles include at least one selected from the group consisting of silica, alumina, and titania.

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

Examples of the pore-forming agent include a liquid pore-forming agent and a solid pore-forming agent. From the viewpoint of further enhancing the effect of suppressing oxidative deterioration of the separator and ensuring higher IS life performance, it is preferable to use at least oil as the pore-forming agent. As the pore-forming agent, one type may be used alone, or two or more types may be used in combination. Oil may be used in combination with other pore-forming agents. A liquid pore-forming agent and a solid pore-forming agent may be used in combination. At room temperature (temperature of 20 ° C. or higher and 35 ° C. or lower), a liquid pore-forming agent is classified as a liquid pore-forming agent, and a solid pore-forming agent is classified as a solid pore-forming agent.

As the liquid pore-forming agent, mineral oil, synthetic oil and the like 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.

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

The oil content in the separator is, for example, 5% by mass or more. From the viewpoint of further enhancing the effect of suppressing oxidative deterioration of the separator, the oil content in the separator is preferably 10% by mass or more, more preferably 12% by mass or more. The oil content in the separator is, for example, 20% by mass or less, and preferably 18% by mass or less. In this case, the resistance of the separator can be further reduced.

The oil content in the separator is 5% by mass or more and 20% by mass or less (or 18% by mass or less), 10% by mass or more and 20% by mass or less (or 18% by mass or less), or 12% by mass or more and 20% by mass or less. (Or 18% by mass or less) may be used.

As the surfactant as a penetrant, for example, either an ionic surfactant or a nonionic surfactant may be used. As the surfactant, one type may be used alone, or two or more types may be used in combination.

The amount of the 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. The amount of the penetrant is, for example, 10 parts by mass or less, and may be 5 parts by mass or less.

The amount of the penetrant in the separator is 0.1 part by mass or more (or 0.5 part by mass or more) and 10 parts by mass or less, or 0.1 part by mass or more (0.5 part 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 penetrant 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 penetrant is, for example, 5% by mass or less, and may be 10% by mass or less.

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

The separator may be either one having a rib or one having no rib. The separator having ribs includes, for example, a base portion and ribs erected from the surface of the base portion. The ribs may be provided on only one surface of the separator or each base portion, or may be provided on both surfaces.

The thickness of the separator is, for example, 0.1 mm or more. The thickness of the separator may be 0.3 mm or less. In a separator having ribs, the thickness of the separator means the thickness of the base portion. The thickness of the separator is the thickness of the portion of the separator facing the region where the electrode material of the electrode plate is arranged. When a sticking member (mat, pacing paper, etc.) is stuck to the separator, the thickness of the sticking member shall not be included in the thickness of the separator.

The ribs may be formed on the sheet when the resin composition is extruded. Further, the ribs may be formed by pressing the sheet with a roller having a groove corresponding to each rib after the resin composition is formed into a sheet or after the pore-forming agent is removed.

When the separator has ribs, the height of the ribs may be 0.05 mm or more. Further, the height of the rib may be 1.2 mm or less. The height of the rib is the height of the portion protruding from the surface of the base portion (protruding height).

The height of the rib provided in the region facing the positive electrode plate of the separator may be 0.4 mm or more. The height of the rib provided in the region facing the positive electrode plate of the separator may be 1.2 mm or less.

(Analysis of separator or measurement of size)
For the analysis of the separator or the measurement of the size, the separator taken out from the lead storage battery at the initial stage of use is used.

The separator removed from the lead acid battery is washed and dried prior to analysis or measurement.

Cleaning and drying of the separator taken out from the lead storage battery is performed by the following procedure. The separator taken out from the lead storage battery is immersed in pure water for 1 hour to remove sulfuric acid in the separator. Next, the separator is taken out from the soaked liquid, and allowed to stand for 16 hours or more in an environment of 25 ° C. ± 5 ° C. to dry. When the separator is taken out from the lead storage battery, the separator is taken out from the lead storage battery in a fully charged state.

(Separator thickness, base thickness, and rib height)
The thickness of the separator (or the base portion) is obtained by measuring and averaging the thicknesses of five arbitrarily selected points in the cross-sectional photograph of the separator.

The height of the rib is determined by averaging the height from one surface of the base portion of the rib measured at 10 arbitrarily selected points of the rib in the cross-sectional photograph of the separator.

(Oil content in separator)
A sample (hereinafter referred to as sample F) is prepared by processing the main part of the separator into a strip shape. In the separator having ribs, the base portion is processed into a strip shape so as not to include the ribs in the main part of the separator to prepare the sample F.

Approximately 0.5 g of sample F is sampled and weighed accurately to determine the initial sample mass (m0). The weighed sample F is placed in a glass beaker of appropriate size and 50 mL of n-hexane is added. Next, the oil contained in the sample F is eluted into n-hexane by applying ultrasonic waves to the sample together with the beaker for about 30 minutes. Next, the sample is taken out from n-hexane, dried in the air at room temperature (temperature of 20 ° C. or higher and 35 ° C. or lower), and then weighed to determine the mass (m1) of the sample after oil removal. Then, the oil content is calculated by the following formula. The oil content is obtained for 10 samples F, and the average value is calculated. The obtained average value is taken as the content of oil in the separator.
Oil content (% by mass) = (m0-m1) / m0 × 100

(Content of inorganic particles in separator)
A part of the sample F prepared in the same manner as above is collected, weighed accurately, placed in a platinum crucible, and heated with a Bunsen burner until no white smoke is emitted. Next, the obtained sample is heated in an electric furnace (in an oxygen stream at 550 ° C. ± 10 ° C.) for about 1 hour to incinerate, and the ashed product is weighed. The ratio (percentage) of the mass of the ash to the mass of the sample F is calculated and used as the content (% by mass) of the above-mentioned inorganic particles. The content of the inorganic particles is obtained for 10 samples F, and the average value is calculated. The obtained average value is taken as the content of inorganic particles in the separator.

(Content of penetrant in separator)
A part of the sample F prepared in the same manner as above is collected, weighed accurately, and then dried at room temperature (temperature of 20 ° C. or higher and 35 ° C. or lower) in a reduced pressure environment lower than the atmospheric pressure for 12 hours or more. The dried product is placed in a platinum cell, set in a thermogravimetric measuring device, and heated from room temperature to 800 ° C. ± 1 ° C. at a heating rate of 10 K / min. The weight loss when the temperature is raised from room temperature to 250 ° C. ± 1 ° C. is taken as the mass of the penetrant, and the ratio (percentage) of the mass of the penetrant to the mass of the sample F is calculated. (Mass%). As a thermogravimetric measuring device, T.I. A. Q5000IR manufactured by Instrument Co., Ltd. is used. The content of the penetrant is obtained for 10 samples F, and the average value is calculated. The obtained average value is taken as the content of the penetrant in the separator.

(Pole plate group)
The electrode plate group includes at least one positive electrode plate, at least one negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate. When the electrode plate group includes two or more positive electrode plates, it is sufficient that at least one of the pair of lower corners is chamfered in at least one positive electrode plate. From the viewpoint of easily ensuring higher IS life performance, at least one of the pair of lower corners is chamfered in 50% or more (preferably 80% or more) of the number of positive electrode plates included in the electrode plate group. Is preferable. Among the positive electrode plates included in the electrode plate group, the ratio of the number of positive electrode plates in which at least one of the pair of lower corners is chamfered is 100% or less. In all of the positive electrode plates included in the electrode plate group, at least one of the pair of lower corners may be chamfered.

The lead-acid battery may be provided with one electrode plate group or may be provided with two or more lead-acid batteries. When the lead-acid battery includes two or more electrode plates, at least one electrode plate group may include a positive electrode plate in which at least one of a pair of lower corners is chamfered. From the viewpoint of easily ensuring higher IS life performance, in 50% or more (preferably 80% or more) of the number of electrode plates included in the lead-acid battery, at least one of the pair of lower corners of the electrode group is formed. It is preferable to have a chamfered positive electrode plate. Of the electrode plate group included in the lead storage battery, the ratio of the electrode plate group including the positive electrode plate in which at least one of the pair of lower corners is chamfered is 100% or less. It is preferable that all of the electrode plates included in the lead-acid battery include a positive electrode plate in which at least one of the pair of lower corners is chamfered.

When the electrode plate group includes two or more negative electrode plates, the content of the Tl element and the Sb element in the negative electrode electrode material may be in the above range in at least one negative electrode plate. From the viewpoint of easily ensuring higher IS life performance, the content of Tl element and Sb element in the negative electrode electrode material is 50% or more (preferably 80% or more) of the number of negative electrode plates contained in the electrode plate group. It is preferably in the above range. Among the negative electrode plates included in the electrode plate group, the ratio of the number of negative electrode plates in which the content of Tl element and Sb element in the negative electrode electrode material is in the above range is 100% or less. The contents of the Tl element and the Sb element in the negative electrode electrode material may be in the above range in all the negative electrode plates included in the electrode plate group.

The lead-acid battery may be provided with one electrode plate group or may be provided with two or more lead-acid batteries. When the lead storage battery includes two or more electrode plate groups, at least one electrode plate group may include a negative electrode plate in which the content of Tl element and Sb element in the negative electrode electrode material is in the above range. .. From the viewpoint of easily ensuring higher IS life performance, in 50% or more (preferably 80% or more) of the number of electrode plates contained in the lead storage battery, the electrode plates are the Tl element and the Sb element in the negative electrode electrode material. It is preferable to have a negative electrode plate whose content is in the above range. Among the electrode plates included in the lead storage battery, the proportion of the electrode plates including the negative electrode plates in which the contents of the Tl element and the Sb element in the negative electrode electrode material is in the above range is 100% or less. It is preferable that all of the electrode plates included in the lead storage battery include a negative electrode plate in which the content of Tl element and Sb element in the negative electrode electrode material is in the above range.

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

The specific gravity of the electrolytic solution at 20 ° C. is, for example, 1.10 or more. The specific gravity of the electrolytic solution at 20 ° C. may be 1.35 or less. It should be noted that these specific gravities are values for the electrolytic solution of the lead-acid battery which has already been used and is in a fully charged state.

FIG. 1 is a plan view showing the appearance of the electrode plate 100 (positive electrode plate or negative electrode plate) used in the lead storage battery according to the embodiment of the present invention. In the example of FIG. 1, the electrode plate 100 is a positive electrode plate, but it may be a negative electrode plate. In FIG. 1, the state of the current collector covered with the electrode material is also shown by omitting the description of the electrode material in a part of the electrode plate 100.

The electrode plate (positive electrode plate) 100 includes a current collector (positive electrode current collector) 101 and an electrode material (positive electrode material) 102 held by the current collector 101. The current collector 101 is an expanded grid in the example of FIG. The current collector 101 may be a punched current collector or a cast current collector. The positive electrode current collector 101 includes a grid portion 103, a transverse bone portion 104, and an ear portion 106. The lateral bone portion 104 is provided at one end of the lattice portion 103. The selvage portion 106 is provided in the lateral bone portion 104.

The approximate shape of the electrode plate 100 excluding the selvage portion 106 is a rectangular shape having a width W and a height H, but a pair of lower corners of the electrode plate 100 are chamfered. As a result, the cutout portions X1 and X2 from which the electrode plate 100 is cut off are formed at each corner.

The contour shape of the electrode plate 100 is the contour shape of the portion where the electrode material of the electrode plate 100 exists. The contour shape of the electrode plate 100 corresponds to a straight line portion L1 parallel to the horizontal direction of the electrode plate 100 corresponding to the bottom surface of the portion where the electrode material exists when the electrode plate 100 is viewed from the front, and the sides of both sides thereof. Two straight line portions L2 parallel to the vertical direction of the electrode plate 100, a straight line portion L3 parallel to the straight line portion L1 corresponding to the upper side, and a straight line portion L1 and a straight line portion L2 are connected at the lower corner portion. It has a connection portion C and. In the illustrated example, the connecting portion C is composed of a straight line inclined with respect to the straight line portions L1 and L2, but the shape of the connecting portion C is not limited to this case.

The extension line extending the straight line portion L1 to the L2 side is referred to as E1, and the extension line extending the straight line portion L2 to the L1 side is referred to as E2. In the electrode plate 100, in the pair of lower corners, the region surrounded by the extension line E1, the extension line E2, and the connection portion C is the missing portion X1 in which the electrode plate 100 is cut off by chamfering the corner portion. And X2. The area of the missing portion X1 is S1, and the area of the missing portion X2 is S2. By forming such cutout portions X1 and X2, a space is formed at the bottom of the electric tank, and the positive electrode material that has fallen off can be accommodated in this space. As a result, high IS life performance can be ensured even when a negative electrode plate in which the content of Tl element and Sb element in the negative electrode electrode material is in a specific range is used.

FIG. 2 shows the appearance of an example of a lead storage battery according to an embodiment of the present invention.
The lead-acid battery 1 includes an electric tank 12 for accommodating a plate group 11 and an electrolytic solution (not shown). The inside of the electric tank 12 is partitioned into a plurality of cell chambers 14 by a partition wall 13. One electrode plate group 11 is housed in each cell chamber 14. The opening of the battery case 12 is closed by a lid 15 including a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a liquid spout 18 for each cell chamber. At the time of refilling water, the liquid spout 18 is removed and the refilling liquid is replenished. The liquid spout 18 may have a function of discharging the gas generated in the cell chamber 14 to the outside of the battery.

The electrode plate group 11 is configured by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 via a separator 4, respectively. Here, the bag-shaped separator 4 accommodating the negative electrode plate 2 is shown, but the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, the negative electrode shelf portion 6 for connecting the plurality of negative electrode plates 2 in parallel is connected to the through connection body 8, and the positive electrode shelf portion for connecting the plurality of positive electrode plates 3 in parallel is connected. 5 is connected to the positive electrode column 7. The positive electrode column 7 is connected to the 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 electrode column 9 is connected to the negative electrode shelf portion 6, and the penetration connecting body 8 is connected to the positive electrode shelf portion 5. The negative electrode column 9 is connected to the negative electrode terminal 16 outside the lid 15. Each through-connecting body 8 passes through a through-hole provided in the partition wall 13 and connects the electrode plates 11 of the adjacent cell chambers 14 in series.

Hereinafter, the method for evaluating the IS life performance will be described.
In the following procedure, the number of cycles until the terminal voltage of the lead-acid battery reaches 7.2V (1.2V / cell) is obtained and used as an index of IS life performance.
(A) After the lead storage battery is placed in a cooling chamber at 0 ° C. ± 1 ° C. for at least 16 hours after the full charge is completed, the temperature of the electrolytic solution in any of the cells in the center is 0 ° C. ± 1 ° C. To confirm.
(B) The lead-acid battery is discharged for 1.0 second at a current (A) that is 10 times the value of Ah described as the rated capacity.
(C) The lead-acid battery is discharged for 25 seconds at a current (A) 0.83 times the value of Ah described as the rated capacity.
(D) The lead-acid battery is charged at a voltage of 14.0 V (2.33 V / cell) for 30 seconds.
(E) The discharge and charge of (b) to (c) above are repeated as one cycle. At this time, a minute current (20 mA) is discharged every 30 cycles for 6 hours.
(F) In the above (b), the number of cycles when the terminal voltage becomes less than 7.2V (1.2V / cell) is obtained.

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

<< Lead-acid batteries A1 to A14 and B1 to B17 >>
Each lead-acid battery was manufactured using a separator and an electrode plate according to the following procedure. The table shows the contents of Tl element and Sb element in the negative electrode electrode material obtained by the above-mentioned procedure, and also shows whether or not the lower corner of the used electrode plate is chamfered.

(1) Preparation of positive electrode plate A positive electrode paste was prepared by mixing lead oxide, a reinforcing material (synthetic resin fiber), water and sulfuric acid. The amount of the reinforcing material in the positive electrode material measured by the procedure described above was 0.15% by mass. A positive electrode paste is filled in the mesh portion of an expanded lattice made of a Pb-Ca-Sn alloy that does not contain antimony, aged and dried, and an unchemical positive electrode plate having a width of 100 mm, a height of 110 mm, and a thickness of 1.6 mm. Got

(2) Preparation of negative electrode plate Lead oxide, carbon black, barium sulfate, lignin, reinforcing material (synthetic resin fiber), water, sulfuric acid, thallium (III) oxide if necessary, and antimony trioxide if necessary. Was mixed to prepare a negative electrode paste. A negative electrode paste is filled in the mesh portion of an expanded lattice made of a Pb-Ca-Sn alloy that does not contain antimony, aged and dried, and an unchemical negative electrode plate having a width of 100 mm, a height of 110 mm, and a thickness of 1.3 m. Got The amount of carbon black, barium sulfate, lignin, and synthetic resin fiber used is 0.3% by mass, respectively, as the amount of each component measured by the procedure described above for the negative electrode plate taken out from the fully charged lead-acid battery. .Adjusted to 1% by weight, 0.1% by weight and 0.1% by weight. The amount of thallium (III) oxide and antimony trioxide used is the value shown in the table for the contents of Tl element and Sb element measured by the procedure described above for the negative electrode plate taken out from the fully charged lead-acid battery. Adjusted to. The Sb content of the negative electrode material in the lead-acid batteries other than B12 to B15 was 5 to 30 ppm.

(3) Chamfering at the lower corner of the electrode plate When a electrode plate with a chamfered lower corner is used in each lead-acid battery, such an electrode plate may be the positive electrode plate produced in (1) above. It was produced by C-chamfering the corners and their periphery at both of the pair of corners at the bottom of the negative electrode plate produced in (2) above. When the electrode plate is viewed from the front, the shape of the portion removed by chamfering (that is, the cut-off portion) is a right-angled isosceles triangle with a height of 17 mm, respectively, and the areas of the cut-out portion S1 and S2. The total area S was 289 mm ² . In this case, the ratio R1 of the total area S of the missing portion was 2.6%.

(4) Separator A resin composition containing 100 parts by mass of polyethylene, 160 parts by mass of silica particles, 80 parts by mass of paraffin-based oil as a pore-forming agent, and 2 parts by mass of a penetrant is extruded into a sheet and then extruded. A microporous film was prepared by removing a part of the pore-forming agent. The oil content of the separator determined by the procedure described was 12-18% by mass. Next, a sheet-shaped microporous membrane was folded in half to form a bag, and both ends of the overlapped ends were welded to obtain a bag-shaped separator. The bag-shaped separator was provided with a rib (outer rib) protruding on the outer surface. The height of the outer rib was 0.6 mm, and the thickness of the base portion was 0.20 mm.

(5) Preparation of Lead-acid Battery The unchemical negative electrode plate was housed in a bag-shaped separator and laminated with the positive electrode plate to form a group of electrode plates with 7 unchemical negative electrode plates and 6 unchemical positive electrode plates. ..

The ears of the positive electrode plate and the ears of the negative electrode plate were welded to the positive electrode shelf and the negative electrode shelf by a cast-on-strap (COS) method, respectively. The electrode plate group is inserted into a polypropylene electric tank, an electrolytic solution is injected, and chemical conversion is performed in the electric tank. The rated voltage is 12 V and the rated capacity is 30 Ah (5-hour rate capacity (Ah described in the rated capacity). A liquid-type lead-acid battery with a current (A) of 1/5 of the value (capacity when discharging)) was assembled. In the battery case, six electrode plates are connected in series.

A sulfuric acid aqueous solution was used as the electrolytic solution. The specific gravity of the electrolytic solution after chemical conversion at 20 ° C. was 1.285.

The table shows the results of evaluating the IS life performance of each lead-acid battery by the procedure described above. In the table, the IS life performance is shown as a relative value with the number of cycles of the lead storage battery B1 as 100.
In addition, A1 to A14 are examples. B1 to B17 are comparative examples.

As shown in Table 1, when a electrode plate with unchamfered lower corners is used, even if the mass-based content of Tl element in the negative electrode electrode material is adjusted to 1 ppm or more and less than 33 ppm, the negative electrode is used. The IS life performance is lower than when the electrode material does not contain the Tl element (comparison between B1 and B2 to B8). Further, when the negative electrode material does not contain the Tl element, the IS life performance is deteriorated even if a positive electrode plate having a chamfered lower corner is used (comparison between B1 and B10). From these results, it is expected that the IS life performance will be deteriorated even if the content of Tl element in the negative electrode electrode material is within the above range and even if the positive electrode plate whose lower corner is not chamfered is used. .. However, when a positive electrode plate having a chamfered lower corner and a negative electrode plate having a mass-based content of Tl element of 1 ppm or more and less than 33 ppm in the negative electrode electrode material are actually combined, the IS life performance is improved. (Comparison of B1 and B10 with A1 to A7). In this way, controlling the content of Tl element in the negative electrode material to a specific range has an effect on IS life performance when combined with a electrode plate whose lower corners are not chamfered and at the lower part. The behavior differs greatly depending on whether it is combined with a positive electrode plate whose corners are chamfered. When the mass-based content of Tl element in the negative electrode electrode material is 33 ppm or more, the IS life performance is greatly deteriorated regardless of whether the lower corner of the electrode plate is chamfered or not (B8 and B9). Comparison between A7 and B11), and there is no difference in the results between B9 and B11.

As shown in Table 2, when the negative electrode plate whose lower corner is not chamfered is used, the IS life performance is further improved as compared with the case where the negative electrode plate whose lower corner is chamfered is used. (Comparison of A1-A7 and A8-A14).

As shown in Table 3, when the mass-based content of Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm, even if a positive electrode plate having a chamfered lower corner is used, it is still in the negative electrode material. When the mass-based content of the Sb element of Sb element exceeds 40 ppm, the effect of improving the IS life performance is not obtained at all (comparison between A10 and A14 and B12 to B15). By setting the content of the Sb element in the negative electrode electrode material to less than 40 ppm, it is considered that the effect of chamfering the Tl element and the lower corner of the positive electrode plate becomes apparent.

The lead-acid battery according to the above aspect of the present invention is suitable, for example, for IS applications (lead-acid batteries for ISS vehicles, etc.), power sources for starting various vehicles (automobiles, motorcycles, etc.), and the like. Further, the lead storage battery may be used as a power source for an industrial power storage device (such as an electric vehicle). It should be noted that these uses are merely examples, and the uses of the lead storage battery according to the above aspect of the present invention are not limited to these.

1: Lead storage battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf, 6: Negative electrode shelf, 7: Positive electrode column, 8: Through connector, 9: Negative electrode column, 11: Pole 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, 100: electrode plate, 101: current collector (positive electrode collection) Electrode), 102: Electrode material (positive electrode material), 103: Lattice, 104: Crossbone, 106: Ear

Claims (7)

It ’s a lead-acid battery.
The lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolytic solution.
The positive electrode plate comprises a positive electrode current collector and a positive electrode material.
The negative electrode plate comprises a negative electrode current collector and a negative electrode material.
At least one of the pair of lower corners of the positive electrode plate is chamfered.
The negative electrode material contains a Tl element and contains.
The content of Tl element in the negative electrode material is 1 ppm or more and less than 33 ppm on a mass basis.
A lead-acid battery in which the negative electrode material does not contain Sb element or contains Sb element, and the content of Sb element in the negative electrode material is 40 ppm or less on a mass basis. The lead-acid battery according to claim 1, wherein the negative electrode plate has the pair of corners not chamfered. The lead-acid battery according to claim 1 or 2, wherein the current collector of the positive electrode plate is an expanded lattice. The separator comprises polyolefin and
The lead-acid battery according to any one of claims 1 to 3, wherein the polyolefin contains at least ethylene units. The lead-acid battery according to any one of claims 1 to 4, wherein the separator is bag-shaped and houses the negative electrode plate. The lead-acid battery according to any one of claims 1 to 5, wherein the separator contains oil. The lead-acid battery according to claim 6, wherein the content of the oil in the separator is 12% by mass or more and 18% by mass or less.

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