JP2021068549A - Lead-acid battery - Google Patents

Abstract

SOLUTION: A 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 includes a positive electrode current collector and a positive electrode material held by the positive electrode current collector. The negative electrode plate includes a negative electrode current collector and a negative electrode material held by the negative electrode current collector. The positive electrode current collector and the negative electrode current collector have a lattice portion, a first transverse bone portion provided at one end portion of the lattice portion, and an ear portion provided at the first transverse bone portion. In at least one of the positive electrode plate and the negative electrode plate, at least one of a pair of corner portions of the end portion opposite to the first transverse bone portion is chamfered. The negative electrode material contains carbon, and the BET specific surface area of carbon is 800 m2/g or more.SELECTED DRAWING: Figure 2

Description

The present invention relates to a lead storage battery.

Lead-acid batteries are used for various purposes such as in-vehicle use and industrial use. In particular, with respect to lead-acid batteries for automobiles, as the use of idling stop vehicles expands, it is required to improve the life performance in the partial state of charge (PSOC).

For example, lead-acid batteries are used in PSOC during charge control and idling stop start (ISS). Therefore, lead-acid batteries used in such applications are required to have excellent life performance in cycle tests under PSOC conditions. In this case, the progress of stratification tends to be a factor that determines the life (hereinafter, referred to as "IS life").

Normally, in a lead-acid battery for general starting, when it is charged to a state close to overcharge or full charge, convection of an electrolytic solution is generated due to gas generation, and stratification is suppressed. However, lead-acid batteries for idling stop vehicles are unlikely to be overcharged or nearly fully charged. As a result, the stratification of the electrolytic solution proceeds by continuing to be used in the PSOC state, the softening of the positive electrode active material and the accumulation of lead sulfate in the positive and negative electrode active materials are promoted, and the IS life tends to be shortened.

Patent Document 1 describes in a liquid lead-acid battery for an idling stop vehicle, in a state where the positive electrode active material is already formed, Sb is converted into metal Sb and contains 0.03 mass% or more and 0.3 mass% or less, and Sn is contained in metal Sn. It is proposed that the content should be 0.05 mass% or more and 1.0 mass% or less in terms of.

Patent Document 2 proposes a configuration in which a lead storage battery using an expanded lattice is provided with cut portions at two corners of the bottom of the electrode plate among the four corners of at least one electrode plate of the positive electrode plate and the negative electrode plate. ing.

Japanese Unexamined Patent Publication No. 2013-140678 Japanese Unexamined Patent Publication No. 2008-204639

In lead-acid batteries, stratification is suppressed and IS life is improved.

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, and the positive electrode plate includes a positive electrode current collector and the positive electrode current collector. The negative electrode plate comprises a positive electrode material held on the body, and the negative electrode plate comprises a negative electrode current collector and a negative electrode material held on the negative electrode current collector, and the positive electrode current collector and the negative electrode collector. The electric body has a lattice portion, a first transverse bone portion provided at one end of the lattice portion, and an ear portion provided at the first transverse bone portion, and includes the positive electrode plate and the positive electrode plate. In at least one of the negative electrode plates, at least one of the pair of corners of the end opposite to the first transverse bone portion is chamfered, the negative electrode material contains carbon, and the BET ratio of the carbon. It relates to a lead storage battery having a surface area of 800 m ^{2 / g or more.}

According to the present invention, the IS life of the lead storage battery is improved because the stratification is suppressed.

It is a top view which shows the appearance of the current collector 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.

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 held by the positive electrode current collector. The negative electrode plate includes a negative electrode current collector and a negative electrode material held by the negative electrode current collector.

The positive electrode current collector and the negative electrode current collector have a lattice portion, a first lateral bone portion provided at one end of the lattice portion, and an ear portion provided at the first lateral bone portion. In at least one of the positive electrode plate and the negative electrode plate, at least one of the pair of corners of the end portion opposite to the first transverse bone portion is chamfered. The negative electrode material contains carbon, and the BET specific surface area of carbon is 800 m ² / g or more. Hereinafter, the surface provided by chamfering is also referred to as a “cut surface”. Chamfering means that the corners of the corners are rounded or formed diagonally. The chamfer may be a C chamfer or an R chamfer. Further, the fact that the corners are chamfered does not necessarily mean that the processing for removing the corners is performed. For example, the corners are not removed without the corners being removed. This includes the case of forming a shaped electrode plate.

In a lead-acid battery, lead sulfate is generated on both the positive electrode plate and the negative electrode plate and water is generated on the positive electrode during discharge. On the other hand, during charging, metallic lead, lead dioxide, and sulfuric acid are produced from lead sulfate and water. When used in a partially charged state for a long period of time, the amount of lead sulfate accumulated inevitably increases, so that the specific gravity of the electrolytic solution decreases. If the electrolytic solution is not sufficiently agitated during charging, a difference in the concentration of sulfuric acid occurs between the upper part and the lower part of the electrolytic solution, resulting in stratification. If the use is continued in such an environment, the charge / discharge efficiency decreases from the upper part where the specific gravity of the electrolytic solution is low, and the life is reached. In addition, the positive electrode material may fall off from the positive electrode plate due to softening and deterioration, and may reach the end of its life. In addition, lead sulfate is easily dissolved in the electrolytic solution at the upper part where the specific gravity of the electrolytic solution is low, lead ions generated by the dissolution are reduced at the negative electrode, and lead crystals precipitated in the form of dendrite penetrate the separator and have a life due to permeation short circuit. It may lead to.

In particular, in a lead-acid battery in which the corners of the electrode plate are chamfered, it has been found that stratification is likely to proceed because the electrolytic solution tends to stay below the cut surface. However, it was found that the IS life was remarkably improved by including carbon having a BET specific surface area of 800 m ^{2 / g or more in the negative electrode material, which led to the present invention.}

The reason why the IS life is remarkably improved is that ^{by including carbon having a BET specific surface area of 800 m 2} / g or more in the negative electrode material, gas generation is promoted even in a partially charged state, and the electrolytic solution Stirring is induced. Carbon is considered to act as an active site in a gas generation reaction, and by using carbon having a large specific surface area, sufficient gas generation can proceed even under partial charging conditions. In order to obtain the above effect sufficiently, the carbon content in the negative electrode material may be 0.2% by mass or more.

On the other hand, when carbon having a large specific surface area is added, the charging efficiency is lowered by the amount of gas generated, which may lead to a decrease in IS life. That is, the effect of improving the IS life by carbon having a large specific surface area may be offset by the side effect of the decrease in IS life due to the decrease in charging efficiency. However, in the case of a lead-acid battery provided with a cut surface, the improvement effect greatly exceeds the side effects, and the IS life is significantly improved.

When the current collector is an expanding lattice, the corners of the electrode plates are chamfered in advance to form a cut surface when producing a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated via a separator. By setting it, it is possible to prevent the corners from being deformed due to interference with the manufacturing apparatus. As a result, it is possible to suppress the occurrence of an initial battery short circuit (see Patent Document 2). In particular, when the positive electrode current collector is an expanding lattice, since the lattice bone is thick, once the corners are deformed, it is difficult to return to the original state, and an initial battery short circuit is likely to occur. On the other hand, when the current collector is a current collector other than the expanding lattice (for example, a punched current collector or a cast current collector), it has a frame bone on the entire outer circumference of the current collector. When manufacturing the electrode plate group, the corner portion is not easily deformed (regardless of the presence or absence of the cut surface), and the problem of initial battery short circuit is unlikely to occur.

On the other hand, the effect of suppressing stratification and the effect of improving the IS life in a lead-acid battery provided with a cut surface are obtained not only when an expanded lattice is used but also when a punched current collector or a cast current collector is used. A lead-acid battery using an expanded lattice is particularly useful because it improves the IS life and suppresses the problem of initial battery short circuit.

The cut surface can be manufactured, for example, in the case of an expanding lattice, by removing a part of the corner portion of the rectangular plate. However, the present invention is not limited to this. In the case of a punched current collector or a cast current collector, the frame bone may be formed so that the corners have a chamfered or curved outer edge.

The decrease in the electrode plate area reduced by chamfering (hereinafter, referred to as “cut area”) may be 1% or more of the area of the positive electrode plate or the negative electrode plate before chamfering. When the ratio R1 of the cut area to the electrode plate area before chamfering is 1% or more, the retention of the electrolytic solution becomes remarkable, and when carbon is not contained, the problem of a decrease in IS life due to the progress of stratification is likely to occur. .. However, in the lead-acid battery of the present embodiment, ^{by including carbon having a BET specific surface area of 800 m 2} / g or more in the negative electrode material, a decrease in IS life is suppressed even when the ratio R1 is 1% or more. IS life is rather improved. On the other hand, in order to maintain high battery characteristics (low temperature output, capacity, etc.), the ratio R1 may be set to 6% or less. The ratio R1 may be 2% or more, or 4% or less.

The ratio R1 may be 1% or more and 6% or less, 2% or more and 6% or less, or 2% or more and 4% or less.

The electrode plate area refers to the projected area when the positive electrode plate or the negative electrode plate (excluding the ears) is projected in the normal direction of the electrode plate surface. The cut area refers to the area of the cut portion (for example, the portion removed by chamfering) at the corner of the end opposite to the lateral bone portion having the ears of the positive electrode plate or the negative electrode plate. It is calculated by the method of.

Normally, the positive electrode plate and the negative electrode plate have a substantially rectangular shape except for the ear portion. The contour of the projected shape of the positive electrode plate and the negative electrode plate is a straight line portion L1 extending parallel to the first direction (usually the horizontal direction) which is the extending direction of the transverse bone (first transverse bone portion) on the opposite side of the ear portion. And a straight line portion L2 extending parallel to the second direction (usually the vertical direction) intersecting the first direction, and the straight line portions L1 and L2 are connected via a connecting portion C. The connecting portion C may be configured to include straight lines and / or curves tilted from the first and second directions.

Consider an extension line E1 in which the straight portion L1 is extended to the L2 side and an extension line E2 in which the straight portion L2 is extended to the L1 side (see FIG. 1). The cut area is obtained by calculating the area S of the region surrounded by the extension line E1, the extension line E2, and the connecting portion C. In the first direction, when cutting the sides of the pair of corner portions, the cut area S, the sum of the areas S ₁ and S ₂ on both sides of the cut portion.

Let A be the plate area of the plate having the chamfered cut surface. The ratio R is calculated by the following formula (1).
(Equation 1)
R1 = S / (A + S)

In particular, when the positive electrode plate or the negative electrode plate is formed by chamfering a substantially rectangular electrode plate, the width of the electrode plate in the first direction is W, and the width of the electrode plate is the second direction of the electrode plate excluding the ears. The ratio R1 is calculated by the following formula (2), where H is the height of.
(Equation 2)
R1 = S / (W × H)

The cut surface may be provided on both the positive electrode plate and the negative electrode plate, or may be provided on only one of the positive electrode plate and the negative electrode plate. When the cut surface is provided on both the positive electrode plate and the negative electrode plate, the cut area may be the same or different between the positive electrode plate and the negative electrode plate. Above all, when the cut surface is provided at at least one of the pair of corners of the positive electrode plate, the improvement in IS life is remarkable. Further, it is preferable that the cut surface is provided only on at least one of the pair of corners of the positive electrode plate and not on the negative electrode plate. The fact that the positive electrode plate or the negative electrode plate is not provided with a cut surface includes the case where the ratio R1 of the cut area represented by the above formula is 0.1% or less.

The cut area may be 1 cm ² or more and 7 cm ² or less, 2 cm ² or more and 7 cm ² or less, or 2 cm ² or more and 4.5 cm ² or less.

Further, the cut surface may be provided on both of the pair of corners of the positive electrode plate or the negative electrode plate, or may be provided on only one of the pair of corners of the positive electrode plate or the negative electrode plate. When the cut surface is provided on both the positive electrode plate and the pair of corners of the negative electrode plate, the cut surface provided on one corner is the shape or cut area of the cut surface provided on the other corner. May be different.

When the cut surface is provided only on _{the positive electrode plate, or when the cut area S +} on the positive electrode plate _{is larger than the cut area S −} on the negative electrode plate, the negative electrode plate has a positive electrode when viewed from the direction facing the positive electrode plate. A non-opposing portion that does not face the plate may exist so as to project outside the cut surface at the corner of the positive electrode plate. The non-opposing portion of the negative electrode plate is unlikely to contribute to the charge / discharge reaction, and a reaction in which gas (hydrogen gas) is generated by applying a charge / discharge voltage can mainly occur. Therefore, by providing the non-opposing portion on the negative electrode plate, hydrogen gas generation is promoted even in the partially charged state. The generated hydrogen gas moves from the bottom side of the electric tank where the non-opposing portion exists toward the liquid level of the electrolytic solution or the vertical direction. As a result, the flow and stirring of the electrolytic solution staying below the cut surface can be induced, and stratification can be effectively suppressed. As a result, the effect of improving the IS life can be further enhanced.

Area S ₀ of the non-facing portions of the negative electrode plate is determined from the shape and the cut area of the cut surface or corner of each of the positive electrode plate and the negative electrode plate. _{The area S 0} of the non-opposing portion of the negative electrode plate may be 1% or more or 2% or more with respect to the area of the negative electrode plate before chamfering. The area S ₀ may be 6% or less or 4% or less with respect to the area of the negative electrode plate before chamfering.

_{Let A −} be the electrode plate area of the negative electrode plate having a chamfered cut surface. The ratio R2 of the non-opposing portion to the area of the negative electrode plate before chamfering is calculated by the following equation (3).
(Equation 3)
_{R2 = S 0 / (A -} + S -)

When the positive electrode plate or the negative electrode plate is formed by chamfering a substantially rectangular electrode plate, the width of the electrode plate in the first direction is W, and the height of the electrode plate in the second direction excluding the ears. Let H be, and the ratio R2 is calculated by the following formula (4).
(Equation 4)
R2 = S ₀ / (W × H)

The ratio R2 may be 1% or more and 6% or less, 2% or more and 6% or less, or 2% or more and 4% or less.

The separator may be bag-shaped. In that case, the separator may accommodate the negative electrode plate. The electrolytic solution is effectively agitated by gas generation, and the effect of suppressing stratification can be enhanced.

For example, in a lead-acid battery mounted on an idling stop vehicle, the number of positive electrode plates and negative electrode plates constituting the electrode plate group is large, and the positive electrode plate, separator, and negative electrode plate are housed in the battery case under pressure. ing. In a lead-acid battery in which pressure is applied to such a group of electrode plates, when the negative electrode plate is housed in a bag-shaped separator, the separator is in close contact with the negative electrode plate. On the other hand, a gap of the electrolytic solution may be interposed between the separator and the positive electrode plate by the rib provided on the separator. In this case, the gas generated at the negative electrode can move upward through the gaps of the electrolytic solution after passing through the separator. As a result, the electrolytic solution impregnated in the separator can be agitated, and the effect of suppressing stratification can be enhanced.

The negative electrode material may contain bismuth (Bi). Since bismuth has a small hydrogen overvoltage, hydrogen gas is likely to be generated by including it in the negative electrode material. Therefore, as the amount of gas generated increases, the electrolytic solution is easily agitated and stratification is easily suppressed. As a result, the effect of improving the IS life can be enhanced. When the negative electrode material contains bismuth, the content of bismuth in the negative electrode material may be 0.0003% by mass or more. Bismuth may be included in the form of compounds such as oxides or sulfates. When bismuth is contained in the form of a compound, the content considering only the mass of the bismuth element contained in the compound may be 0.0003% by mass or more.

The mass of the negative electrode material is the mass when the negative electrode material taken out from the fully charged lead-acid battery is washed with water and dried. The bismuth content in the negative electrode electrode material was determined by disassembling a fully charged lead-acid battery after chemical conversion or in use (preferably at the initial stage of use), washing the taken-out electrode plate with water, drying, and then collecting and crushing the electrode material. It is obtained by dissolving the sample in concentrated nitrate and performing ICP (Inductively Coupled Plasma) luminescence analysis. The initial use battery means a battery that has not been used for a long time and has hardly deteriorated.

The carbon content contained in the negative electrode material and the BET specific surface area of carbon are determined by the following methods.

(Separation of lead)
The negative electrode plate is taken out from the fully charged lead-acid battery, and the negative electrode material is washed with water and dried. Then, the negative electrode material is taken out from the negative electrode plate and pulverized, and the pulverized negative electrode material is reacted with dilute nitric acid having a volume ratio of water 3: nitric acid 1 to dissolve the lead content. Subsequently, the residue after the reaction is filtered using a membrane filter and dried. The residue after drying may contain reinforcing materials such as synthetic resin fibers, carbon, barium sulfate and the like. When the negative electrode material contains a reinforcing material and / or barium sulfate, carbon is separated from the negative electrode material by the following method. Here, let W be the mass of the negative electrode material taken out from the negative electrode plate after drying.

(Measurement of carbon content)
The content of reinforcing material, carbon, and barium sulfate contained in the lead-removed residue is measured using a differential thermal analysis (TG-DTA) device.
First, the residue is weighed. The mass at this time is W0. Next, the sample is heated to 400 ° C. under a nitrogen gas flow to thermally decompose the reinforcing material. Let W1 be the mass when the weight loss of the sample becomes almost constant.

Subsequently, after cooling to 350 ° C., the mixture is heated to 1000 ° C. under an oxygen gas flow to burn carbon. Let W2 be the mass when the weight loss of the sample becomes almost constant. The decomposition temperature of barium sulfate is 1600 ° C., and it exists stably even after heating to 1000 ° C.

From the mass loss during thermal analysis, the contents of reinforcing material, carbon, and barium sulfate can be calculated by the following formula.
Reinforcing material content: W0-W1
Carbon content: W1-W2
Barium Sulfate Content: W2

Therefore, the carbon content (mass%) in the negative electrode material is determined to be 100 × (W1-W2) / W.

(Isolation of carbon)
The lead-removed residue is placed in a crucible and heated to 400 ° C. under a nitrogen gas flow using an electric furnace to thermally decompose the reinforcing material.
After removing the reinforcing material by thermal decomposition, it is cooled to room temperature and pulverized. After the milling material is dispersed in a sufficient amount of water, the carbon is separated from the barium sulfate by a centrifuge. Further, only the separated carbon is dispersed again in a sufficient amount of water and then put into a centrifuge to remove barium sulfate that may be mixed in the carbon. Dispersion in water and separation in a centrifuge may be repeated multiple times. The carbon obtained in the above operation is dried and used as a sample for measuring the specific surface area.

(Measurement of specific surface area)
The specific surface area of carbon can be measured by the BET method. The BET method is an analysis method in which an inert gas having a known molecular size (for example, nitrogen gas) is adsorbed on the surface of a measurement sample, and the surface area is obtained from the adsorbed amount and the occupied area of the inert gas. Nitrogen gas is used as the inert gas.

In the present specification, the fully charged state of a liquid lead-acid battery is defined by the definition of JIS D 5301: 2006. More specifically, the charging terminal of the lead-acid battery measured every 15 minutes in a water tank at 25 ° C. ± 2 ° C. with a current (A) 0.2 times the value of Ah described as the rated capacity. A fully charged state is defined as a state in which the electrolyte density converted into voltage or temperature converted to 20 ° C. is charged three times in a row until it shows a constant value with three significant figures. Further, in the case of a control valve type lead-acid battery, the fully charged state means that the lead-acid battery has a current (A) of 0.2 times the value described as the rated capacity in an air tank at 25 ° C. ± 2 ° C. It is in a state of being charged at a constant current and constant voltage of 2.23 V / cell, and when the charging current (A) at the time of constant voltage charging becomes 0.005 times the value described as the rated capacity, the charging is completed. 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).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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 expanding 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 first lateral bone portion 104, and an ear portion 106. The first lateral bone portion 104 is provided at one end of the lattice portion 103. The ear portion 106 is provided on the first lateral bone portion 104.

The approximate shape of the electrode plate 100 excluding the ear portion 106 is a rectangular shape having a width W and a height H, but the corner portion of the corner opposite to the first lateral bone portion 104 is chamfered. As a result, the cut surface 107 is formed on the electrode plate 100.

The contour shape of the electrode plate 100 is on the side opposite to the first transverse bone portion 104, and the straight portion L1 extending parallel to the extending direction of the first transverse bone portion 104 and the first transverse bone portion 104. It has a straight portion L2 parallel to the direction intersecting the stretching direction, and a connecting portion C connecting the straight portion L1 and the straight portion L2 at the corner. The connecting portion C may be configured to include a straight line and / or a curved line inclined with respect to the straight line portions L1 and L2. The cut surface 107 refers to a slope corresponding to the connecting portion C. The cut surface 107 may be present on one or both of the pair of corners.

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 plate 100, the plate area is reduced by _{the total area S 1} + S ₂ of the area surrounded by the extension line E1, the extension line E2, and the connecting portion C at the pair of corners.

A group of electrode plates can be obtained by laminating a positive electrode plate and a negative electrode plate via a separator using the electrode plate 100. When the obtained electrode plate group is housed in the electric tank, if the cross-sectional shape of the inner wall of the electric tank is rectangular, a gap is formed below the cut surface 107 of the electrode plate 100. This gap is filled with an electrolytic solution. The electrolytic solution existing in this gap is difficult to flow and stir, and it is easy to promote stratification. ^{However, in the present embodiment, by including carbon having a BET specific surface area of 800 m 2} / g or more in the negative electrode material in the negative electrode plate, gas generation can be promoted and the flow and stirring of the electrolytic solution can be induced. .. As a result, the progress of stratification is suppressed and the IS life is improved.

The electrode plate 100 may be used as the positive electrode plate, and a normal electrode plate that is not chamfered by the negative electrode plate may be used. In this case, when the positive electrode plate and the negative electrode plate are overlapped with each other via the separator to form a group of electrode plates, the negative electrode plate is projected from the surface provided by chamfering the positive electrode plate when viewed from the direction facing the positive electrode plate, and the positive electrode plate is formed. A non-opposing portion that does not face the plate is generated. In this negative electrode non-opposing portion, a reaction in which hydrogen gas is generated by applying a charge / discharge voltage can mainly occur. As a result, the electrolytic solution staying below the cut surface of the negative electrode plate flows and is agitated, and stratification can be effectively suppressed.

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

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

The clad type positive electrode plate includes a plurality of porous tubes, a core metal inserted in each tube, a positive electrode material filled in the tube into which the core metal is inserted, and a collective punishment for connecting the plurality of tubes. Equipped with. In the clad type positive electrode plate, the positive electrode material is the positive electrode plate from which the tube, the core metal, and the collective punishment are removed.

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 may have a plurality of alloy layers. It is preferable to use a Pb-Ca alloy or a Pb-Sb alloy for the core metal.

The positive electrode material 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, if necessary.

The unchemical paste type positive electrode plate is obtained by filling the positive electrode current collector with the positive electrode paste, aging and drying, as in the case of the negative electrode plate. After that, an unchemical positive electrode plate is formed. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.

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

(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 electrode material is a negative electrode plate obtained by removing the negative electrode current collector. The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of the processing method include expanding processing and punching processing. It is preferable to use a negative electrode lattice as the negative electrode current collector because it is easy to support the negative electrode material.

The lead alloy used for the negative electrode current collector may be any of Pb-Sb-based alloys, Pb-Ca-based alloys, and Pb-Ca-Sn-based alloys. 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 material contains a negative electrode active material (lead or lead sulfate) whose capacity is developed by a redox reaction, may contain a shrink-proofing agent, barium sulfate, etc., and may contain other additives as necessary. Good.

As the organic shrinkage proofing agent, lignins and / or synthetic organic shrinkage proofing agents may be used. Examples of lignins include lignin, lignin sulfonic acid or a lignin derivative such as a salt thereof (such as an alkali metal salt such as a sodium salt). The synthetic organic shrinkage proofing agent is an organic polymer containing a sulfur element, and generally contains a plurality of aromatic rings in the molecule and also contains a sulfur element as a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group in a stable form is preferable.

The negative electrode material contains carbon having a BET specific surface area of 800 m ² / g or more. As the carbon having such a specific surface area, for example, carbon black such as furnace black, channel black, acetylene black, and ketjen black can be used. The BET specific surface area of carbon ^{may be 1200 m 2} / g or more. BET specific surface area of the carbon, 1600 m ² / g or less, 1500 m ² / g or less, or 1450m may be ² / g or less. These upper and lower limits can be combined arbitrarily.

When the carbon content in the negative electrode material is 0.2% by mass or more, sufficient gas is generated and the IS life can be improved. On the other hand, the carbon content may be 1% by mass or less in terms of suppressing a decrease in charging efficiency due to gas generation and suppressing a liquid reduction amount.

The negative electrode material may further contain bismuth (Bi). When the negative electrode material contains bismuth, the generation of hydrogen gas is promoted in the negative electrode, and the electrolytic solution is easily agitated. As a result, stratification can be suppressed and the effect of improving IS life can be enhanced. The content of bismuth in the negative electrode material may be 0.0003% by mass or more. The bismuth content may be 0.0005% by mass or more. On the other hand, the bismuth content may be 0.003% by mass or less or 0.002% by mass or less in terms of suppressing a decrease in charging efficiency due to gas generation and suppressing a liquid reduction amount. These upper and lower limits can be combined arbitrarily.

Bismuth may be contained in the negative electrode material in the form of a compound such as an oxide or a sulfate. When a part of bismuth is contained in the negative electrode material in the form of a compound, the above-mentioned bismuth content is a content considering only the mass of the bismuth element contained in the compound. The bismuth content is a value in a fully charged state.

The negative electrode active material in the charged state is spongy lead, but the unchemicald negative electrode plate is usually produced using lead powder.

The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying to produce an unchemicald negative electrode plate, and then forming an unchemicald negative electrode plate. The negative electrode paste is prepared by adding water and sulfuric acid to lead powder, an organic shrink-proofing agent, and various additives as necessary, and kneading them. In the aging step, it is preferable to ripen the unchemicald 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, chemical conversion may be performed before assembling the lead-acid battery or the electrode plate group. The chemical formation produces spongy lead.

At least one of the positive electrode plate and the negative electrode plate is configured to have a cut surface at a corner of the electrode plate, for example, as in the electrode plate 100 shown in FIG.

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

The specific gravity of the electrolytic solution at 20 ° C. is, for example, 1.10 g / cm ³ or more. The specific gravity of the electrolytic solution at 20 ° C. ^{may be 1.35 g / cm 3} or less. These specific gravities are values for the electrolytic solution of a ready-made and fully charged lead-acid battery.

(Separator)
A separator is usually arranged between the negative electrode plate and the positive electrode plate. A non-woven fabric, a microporous membrane, or the like is used as the separator. Nonwoven fabric is a mat that is entwined without weaving fibers, and is mainly composed of fibers. For example, 60% by mass or more of the separator is made of fibers. As the fiber, glass fiber, polymer fiber, pulp fiber and the like can be used. The non-woven fabric may contain components other than fibers, for example, an acid-resistant inorganic powder, a polymer as a binder, and the like. The microporous film is a porous sheet mainly composed of components other than fiber components. For example, a composition containing a pore-forming agent (polymer powder, oil, etc.) is extruded into a sheet and then the pore-forming agent is removed. It is obtained by forming pores. Inorganic particles may be included in the composition. As the inorganic particles, for example, ceramic particles such as silica, alumina, and titania are preferable. The microporous membrane is preferably composed mainly of a polymer component. As the polymer component, polyolefins such as polyethylene and polypropylene are preferable.

The separator may be either one having a rib or one having no rib. The rib is erected in a region (base portion) on the surface of the separator that can face the positive electrode plate or the negative electrode plate. The ribs may be provided on only one surface of the separator, or may be provided on both surfaces, respectively. 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. However, from the viewpoint of effectively diffusing the electrolytic solution due to gas generation, the negative electrode plate may be housed in a bag-shaped separator as described above.

(Fiber mat)
The lead-acid battery may further include a fiber mat interposed between the positive electrode plate and the negative electrode plate. Fiber mats, unlike separators, contain sheet-like fiber aggregates. As such a fiber aggregate, a sheet in which fibers insoluble in an electrolytic solution are entangled is used. Such sheets include, for example, non-woven fabrics, woven fabrics, knitting and the like. For example, 60% by mass or more of the fiber mat is made of fibers.

As the fiber, glass fiber, polymer fiber, pulp fiber and the like can be used. Among the polymer fibers, polyolefin fibers are preferable.

FIG. 2 is a partially cutaway perspective view showing the appearance and internal structure of the liquid lead-acid battery according to the embodiment of the present invention.

The lead-acid battery 1 includes an electric tank 12 that houses a electrode 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. In each cell chamber 14, one electrode plate group 11 is stored. 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 rehydration, the liquid spout 18 is removed and the rehydration 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 formed 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 that accommodates 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 connecting body 8, and the positive electrode shelf portion for connecting the plurality of positive electrode plates 3 in parallel. 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 6, and the through connector 8 is connected to the positive electrode shelf 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.

Although FIG. 2 shows an example of a liquid battery (vent type battery), the lead storage battery may be a control valve type battery (VRLA type).

Hereinafter, a method for evaluating each characteristic of the lead storage battery will be described.

In the lead-acid battery according to the above aspect, the IS life is improved by promoting gas generation. Further, when an expanding lattice is used for the current collector, the initial battery short circuit is suppressed by providing a cut surface on the positive electrode plate and / or the negative electrode plate. IS life and initial battery short circuit are evaluated by the following procedure.

(1) IS life The number of cycles until the terminal voltage reaches 7.2V (1.2V / cell) is used as an index of IS life in the following procedure. The minute current discharge in (e) simulates dark current discharge when the engine is stopped.
(A) After the storage battery is placed in a cooling chamber at 0 ° C. ± 1 ° C. for at least 16 hours after the full charge is completed, it is confirmed that the electrolyte temperature of any cell in the center is 0 ° C. ± 1 ° C. To do.
(B) The storage 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 storage battery is discharged for 25 seconds at a current (A) 0.83 times the value of Ah described as the rated capacity.
(D) The storage 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.

(2) Initial battery short circuit (a) In the manufacture of the electrode plate group, visually check whether or not holes are found in the separator due to the bending of the current collector.
(B) A group of electrode plates for which holes in the separator could not be confirmed are housed in an electric tank, an electrolytic solution is injected, and chemical conversion treatment is performed.
(C) The chemical storage battery is discharged for 2.5 seconds at a current (A) of 8.3 times the value of Ah described as the rated capacity. If the voltage after discharge is 9.5 V (1.58 V / cell) or less, it is considered as a discharge failure.
(D) The number of holes in the separator confirmed in (a) and the number of defective discharges in (c) are totaled to obtain the ratio to the total number of samples, which is used as the initial battery short-circuit rate.

[Example]
Hereinafter, embodiments of the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<< Batteries A1 to A16, B1 to B5, C1 to C5 >>
A plurality of lead-acid batteries A1 to A16, B1 to B5, and C1 to C5 having different configurations of the positive and negative electrode plates and / or the carbon content or specific surface area contained in the negative electrode plates were produced by the following procedure.

(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. 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 A negative electrode paste was prepared by mixing lead oxide, carbon black, barium sulfate, lignin, reinforcing material (synthetic resin fiber), water and sulfuric acid. The negative electrode paste is filled in the mesh portion of the expanded lattice made of Pb-Ca-Sn alloy that does not contain antimony, aged and dried, and the unmodified negative electrode plate having a width of 100 mm, a height of 110 mm and a thickness of 1.3 m is filled. Got The amounts of barium sulfate, lignin and synthetic resin fibers were adjusted to be 2.1% by mass, 0.1% by mass and 0.1% by mass, respectively, when measured in a fully charged state. The carbon black having a predetermined BET specific surface area was used, and the content was adjusted so as to have the content shown in Table 1 when measured in a fully charged state.

(3) Formation of cut surface In the lead-acid batteries A1 to A16 and B3 to B5, at least one of the positive electrode plate and the negative electrode plate obtained in (1) and (2) is both opposite to the selvage portion of the electrode plate. The corners of the corners were chamfered to form a cut surface. The shape of the portion removed by forming the cut surface of the electrode plate was a right-angled isosceles triangle with a height of 17 mm, and the cut area was 289 mm ² in total of the removed portions at the corners on both sides. In this case, the ratio R1 of the cut area was 2.6%.

(4) Preparation of Lead-acid Battery A non-chemical negative electrode plate was housed in a bag-shaped separator and laminated with a positive electrode plate to form a group of electrode plates with 7 unchemical negative electrode plates and 6 unchemical positive electrode plates. .. As the bag-shaped separator, a bag-shaped separator having ribs (outer ribs) protruding on the outer surface was used. The height of the outer rib was 0.6 mm.

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 battery case, an electrolytic solution is injected, and chemical conversion is performed in the battery battery. The rated voltage is 12 V and the rated capacity is 30 Ah (5-hour rate capacity (Ah described in rated capacity). Liquid lead-acid batteries A1 to A16 and B1 to B5 with a current (A) of 1/5 of the value of (1)) were assembled. In the battery case, six electrode plates are connected in series.

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

<< Batteries A17 to A21 >>
In the preparation of the negative electrode plate, a negative electrode paste containing lead oxide, carbon black, barium sulfate, lignin, reinforcing material (synthetic resin fiber), bismuth sulfate Bi ₂ (SO ₄ ) ₃ , water, and sulfuric acid was prepared. The amount of dibismuth trioxide added was adjusted so that the amount of Bi contained in the negative electrode material would be the predetermined content shown in Table 1 in terms of elements when measured in a fully charged state.
Moreover, the cut surface was formed only on the positive electrode plate.
Other than this, lead-acid batteries A17 to A21 were produced in the same manner as the lead-acid battery A8.

Table 1 shows the results of evaluating the IS life and the initial battery short circuit of the lead-acid batteries A1 to A21, B1 to B5, and C1 to C5 by the procedure described above. Table 1 also shows the presence or absence of cut surfaces on the positive electrode plate and the negative electrode plate, the BET specific surface area and content of carbon added to the negative electrode, and the content of bismuth added to the negative electrode for each of the lead-acid batteries. There is. In Table 1, the IS life is shown as a relative value with the number of cycles of the lead-acid battery B1 as 100. In addition, the initial battery short circuit is shown as a percentage (ppm) of the rate at which defects occur.
In addition, A1 to A21 are examples. B1 to B5 are comparative examples, in which the BET specific surface area of carbon added to the negative electrode material is ^{less than 800 m 2} / g. C1 to C5 are reference examples, and the BET specific surface area of carbon added to the negative electrode material is 800 m ² / g or more, but no cut surface is formed on either the positive electrode plate or the negative electrode plate.

^{From Table 1, the lead-acid batteries A1 to A21 containing carbon having a BET specific surface area of 800 m 2} / g or more in the negative electrode electrode material and having a cut surface formed on at least one of the positive electrode plate and the negative electrode plate have an IS life. It is improved and the occurrence of defects due to the initial battery short circuit is suppressed.

Lead-acid batteries B1 and B2 have a high rate of failure of initial battery short circuit. This is because the corners of the expanding lattice are deformed and easily bent when the electrode plates are manufactured. When the lattice bone at the corner is bent, the bent portion may penetrate the separator and come into direct contact with the adjacent electrode plate, resulting in a short circuit.

On the other hand, in the lead-acid batteries B3 to B5, by providing a cut surface on at least one of the positive electrode plate and the negative electrode plate, the rate of occurrence of defects due to the initial battery short circuit is reduced. In particular, by providing a cut surface at least on the positive electrode plate, an initial battery short circuit hardly occurs. However, in the lead-acid batteries B3 to B5, the IS life is shortened by providing the cut surface.

However, in the lead-acid batteries A1 to A21, the IS life of the lead-acid battery having a cut surface is greatly improved by including carbon having a ^{BET specific surface area of 800 m 2 / g or more in the negative electrode material.} In particular, the lead-acid batteries A2, A5, A8 and A11 having a cut surface on the positive electrode plate and no cut surface on the negative electrode plate have the same BET specific surface area of carbon added in the same amount to any of the positive and negative electrode plates. The IS life was longer than that of lead-acid batteries (C1 to C4) without a cut surface.

The lead-acid battery lattice body according to the present invention is applicable to control valve type and liquid type lead-acid batteries, and is used for starting power sources for automobiles, motorcycles, etc., and industrial power storage devices for electric vehicles (forklifts, etc.). It can be suitably used as a power source. Above all, it is particularly useful as a power source mounted on an idling stop vehicle.

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 part, 104: First transverse bone part, 106: Ear part, 107: Cut surface

Claims (9)

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 are provided.
The positive electrode plate includes a positive electrode current collector and a positive electrode material held by the positive electrode current collector.
The negative electrode plate includes a negative electrode current collector and a negative electrode material held by the negative electrode current collector.
The positive electrode current collector and the negative electrode current collector include a lattice portion, a first transverse bone portion provided at one end of the lattice portion, and an ear portion provided at the first transverse bone portion. Have,
In at least one of the positive electrode plate and the negative electrode plate, at least one of the pair of corners of the end portion opposite to the first transverse bone portion is chamfered.
A lead-acid battery in which the negative electrode material contains carbon and the BET specific surface area of the carbon is 800 m ^{2 / g or more.} The lead-acid battery according to claim 1, wherein at least one of the pair of corners of the positive electrode plate is chamfered. The lead according to claim 2, wherein the negative electrode plate has a non-opposing portion that projects from the chamfered surface of the positive electrode plate and does not face the positive electrode plate when viewed from a direction facing the positive electrode plate. Storage battery. The lead-acid battery according to any one of claims 1 to 3, wherein the positive electrode current collector is an expanding lattice. The lead-acid battery according to any one of claims 1 to 4, wherein the separator has a bag shape and houses the negative electrode plate. The lead-acid battery according to any one of claims 1 to 5, wherein the carbon content in the negative electrode material is 0.2% by mass or more. The lead-acid battery according to any one of claims 1 to 6, wherein the negative electrode material contains bismuth (Bi), and the content of the bismuth in the negative electrode material is 0.0003% by mass or more. The lead-acid battery according to any one of claims 1 to 7, wherein the reduction in the electrode plate area reduced by the chamfering is 1% or more of the area of the positive electrode plate or the negative electrode plate before the chamfering. .. The lead-acid battery according to any one of claims 1 to 8, which is mounted on an idling stop vehicle.

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