JP6900769B2 - Lead-acid battery - Google Patents

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. The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate includes a negative electrode current collector and a negative electrode material. A carbon material is added to the negative electrode material in order to suppress the accumulation (sulfation) of lead sulfate on the negative electrode plate (Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-154132

However, the suppression of sulfation is still insufficient under the usage conditions of the battery in which sulfation easily progresses. The conditions for using a battery in which sulfation easily progresses are that the battery is used in a state of insufficient charge called a partial charge state (PSOC) when deep discharge is repeated in a charge / discharge cycle, the frequency of charging is low when the battery is used, and so on. There are cases.

One aspect of the present invention is a lead-acid battery, wherein the lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution, and the negative electrode plate is made of a carbon material and at least a part of the carbon material. The present invention relates to a lead-acid battery, which comprises a negative electrode material containing a taken-in conductivity improver.

According to the present invention, sulfation can be suppressed in a lead storage battery.

It is an exploded perspective view which cut out a part which shows the appearance and the internal structure of the lead storage battery which concerns on embodiment of this invention.

One aspect of the present invention is a lead storage battery, which includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate contains a negative electrode material containing a carbon material and a conductivity improver incorporated into at least a part of the carbon material. The carbon material includes at least the first carbon material described later.

By incorporating the conductivity improver into at least a part of the carbon material, the conductivity of the negative electrode material is improved. As a result, sulfation is sufficiently suppressed even under the usage conditions of the battery in which sulfation easily progresses. Such usage conditions include repeated deep discharges in the charge / discharge cycle, infrequent charging when using the battery, and the case where the battery is used in an undercharged state called a partial charge state (PSOC). Be done.

The fact that the conductivity improver is incorporated into the carbon material means that the conductivity improver is present in a relatively strong bonded state with the carbon material. Specifically, this includes the case where the conductivity improver is inserted into the crystal lattice of the carbon material, or the carbon material is doped with the conductivity improver. For example, the conductivity improver forms a compound with a carbon material. The conductivity improver comes into contact with the particle surface of the carbon material by adding a conductivity improver to the electrolytic solution or adding a conductivity improver to the negative electrode paste containing the carbon material at the time of producing the negative electrode. The above-mentioned effect of suppressing sulfation cannot be obtained only by using the above-mentioned effect.

It is known that when lithium is inserted between layers of graphite, when the graphite is immersed in water, a part of the lithium inserted between the layers elutes in water. Therefore, according to the conventional wisdom of technology, in the case of a lead-acid battery in which an aqueous sulfuric acid solution is used as the electrolytic solution, even if the conductivity improver is incorporated into the carbon material used for the negative electrode plate, a part of the conductivity improver in the carbon material is present. Since it flows out to the electrolytic solution, it was considered that there was almost no effect on the conductivity of the negative electrode plate.

On the other hand, according to the above aspect of the present invention, the conductivity improver is incorporated into at least a part of the carbon material. Even if a part of the conductivity improver incorporated in the carbon material is eluted in the electrolytic solution, if even a small amount of the conductivity improver incorporated in the carbon material remains, the use of a battery in which sulfation easily progresses. It was found that the conductivity of the negative electrode plate was significantly improved to the extent that sulfation was sufficiently suppressed even under the conditions. This is because when even a small amount of the conductivity improver remains between the layers of graphite, the conductivity in the c-axis direction of graphite is improved, and accordingly, the plane perpendicular to the c-axis direction of graphite (the plane including the ab-axis direction). It is presumed that this is due to the improvement in the conductivity of the active material in contact with).

(Conductivity improver)
From the viewpoint of improving the conductivity of the negative electrode material, the conductivity improving agent preferably contains at least one of _{an alkali metal and AsF 5.} Alkali metals are incorporated into carbon materials as ions. Alkali metals include lithium, sodium, potassium and the like. Of these, lithium is preferable because it can be easily inserted between graphite layers.

The content of the conductivity improver in the negative electrode material is, for example, 0.002% by mass or less, and 8 parts by mass or less per 100 parts by mass of the first carbon material.

(A) Analysis of Conductivity Improver (A-1) Conductivity Improver Incorporated in Carbon Material It is confirmed that the conductivity improver is incorporated in the carbon material by the following procedure.
The fully charged lead-acid battery is disassembled, the negative electrode plate is taken out, washed with water, and vacuum dried (dried under a pressure lower than atmospheric pressure). Then, the negative electrode material is separated from the negative electrode plate. In the procedure of (B-1) described later, the carbon material is taken out from the negative electrode material, and the first carbon material is separated from the carbon material. The first carbon material is analyzed by X-ray diffraction, Raman spectroscopy, or nuclear magnetic resonance spectroscopy.

In the X-ray diffraction method, it is confirmed that 2θ (angle) corresponds to the interplanar spacing of the crystal, and the conductivity improver is incorporated into the first carbon material based on the diffraction peak appearing in the X-ray diffraction pattern. .. When lithium is inserted between the layers of graphite, the diffraction peak around 26.5 ° attributable to the (002) plane of graphite shifts to the low angle side and appears near 24 °.

In Raman spectroscopy, a G-band peak that reflects the structure of graphite and a D-band peak that reflects irregularities appear. It is confirmed that the conductivity improver is incorporated into the first carbon material based on the intensity ratio (D / G ratio) of the G band peak to the D band peak and the half width of the G band peak. When lithium is inserted between the layers of graphite, the size, position, and shape of the peak of the G band changes.

In nuclear magnetic resonance spectroscopy, it is confirmed that the conductivity improver is incorporated into the carbon material based on the position of the peak appearing in the NMR spectrum. When lithium is inserted between the layers of graphite (in _{the state of LiC 6} ), a peak appears near the chemical shift value of 43 ppm in the Li-NMR spectrum.

(A-2) Content of Conductivity Improver in Negative Electrode Material After confirming that the conductivity improver is incorporated into the first carbon material in (A-1) above, the conductivity improver When is an alkali metal, the content of the conductivity improver in the negative electrode material is determined by the following procedure.

The first carbon material containing the alkali metal is put into a strong acid such as hydrochloric acid or sulfuric acid and heated to elute the alkali metal incorporated in the first carbon material. ICP emission spectroscopic analysis is performed using the solution. Based on the analytical values, the content of alkali metal in the negative electrode material is determined.

In the present specification, the fully charged state of a lead-acid battery means that in the case of a liquid battery, it is charged at 0.2 CA with a constant current until it reaches 2.5 V / cell in a water tank at 25 ° C. .2 CA is in a state of constant current charging for 2 hours. Further, in the case of a control valve type battery, a fully charged state means that a constant current constant voltage charge of 2.23 V / cell is performed at 0.2 CA in an air tank at 25 ° C., and the charging current during constant voltage charging is performed. Charging is completed when the voltage becomes 1 mCA or less.
In the present specification, 1CA is a current value (A) having the same numerical value as the nominal capacity (Ah) of the battery. For example, in the case of a battery having a nominal capacity of 30 Ah, 1CA is 30 A and 1 mCA is 30 mA.

(Carbon material)
The carbon material includes at least a material capable of incorporating a conductivity improver. The carbon material capable of incorporating the conductivity improver preferably contains at least one selected from the group consisting of graphite, hard carbon, and soft carbon, and more preferably contains graphite. The conductivity improver is inserted, for example, between layers of graphite. The graphite may be any carbon material containing a graphite-type crystal structure, and may be either artificial graphite or natural graphite.

Graphite has a large particle size and is difficult to disperse uniformly in the negative electrode material. Therefore, it is difficult to obtain stable conductivity over the entire negative electrode plate. Therefore, the effect of suppressing sulfation by inserting a conductivity improving agent such as lithium between the layers of graphite can be remarkably obtained.

The intensity of a peak appearing in 1300 cm ^-1 or 1350 cm ^-1 or less in the range of the Raman spectrum (D band) and 1550 cm ^-1 or 1600 cm ^-1 peak appearing in the range (G band) of the first carbon material the ratio _I D / _{I G} is, what is 0 to 0.9, and graphite.

Further, the carbon material may further contain carbon black or the like. Examples of carbon black include acetylene black, ketjen black, furnace black, and lamp black.

The carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm, and the conductivity improver may be incorporated into the first carbon material. preferable. The first carbon material incorporating the conductivity improver and the second carbon material are separated and distinguished by a procedure described later.

The powder resistivity ratio R2 / R1 between the first carbon material containing the conductivity improver and the second carbon material contained in the negative electrode plate is preferably 150 or more and 1200 or less, and more preferably 250 or more and 1100 or less. It is more preferably 550 or more and 1050 or less. When the powder resistivity ratio R2 / R1 is 150 or more, sulfation is suppressed. When R2 / R1 is 150 or more and 1200 or less, sulfation is suppressed and the positive electrode material is suppressed from falling off due to an increase in the charging current during overcharging. Further, when R2 / R1 is 1200 or less, the generation of gas from the positive electrode plate is suppressed from an early stage of charging, and the accompanying dropout of the positive electrode material is also suppressed.

When the carbon material incorporates the conductivity improver, the conductivity of the negative electrode material is improved and sulfation is suppressed. However, since the charging current at the time of overcharging increases, the positive electrode lattice is likely to be corroded or stretched, which is likely to cause the positive electrode material (positive electrode active material) to fall off. One of the factors that increase the charging current during overcharging is that when graphite is used as the carbon material, the hydrogen overvoltage becomes small and the polarization of the negative electrode during charging becomes small.

On the other hand, even when a carbon material incorporating a conductivity improver (first carbon material) is used by using the above two types of carbon materials in combination and adjusting the powder resistivity R2 / R1 within the above range. The charging current during overcharging is reduced. As a result, the occurrence of corrosion and elongation of the positive electrode lattice due to the increase in the charging current during overcharging, and the resulting dropout of the positive electrode electrode material are suppressed.

Carbon materials are known to have various powder resistances. It is known that the powder resistance of a powder material changes depending on the shape of the particles, the particle size, the internal structure of the particles, and / or the crystallinity of the particles. Conventional technical wisdom is that the powder resistance of the carbon material is not directly related to the resistance of the negative electrode plate and is not considered to affect the charging current during overcharging.

On the other hand, in the present invention, by controlling the powder resistivity ratio R2 / R1 of the first carbon material and the second carbon material contained in the negative electrode plate in the range of 15 to 155, the effect of suppressing sulfation is maintained. , The charging current at the time of overcharging is reduced. It is considered that this is because the hydrogen overvoltage of the negative electrode is adjusted to an appropriate magnitude when the first carbon material and the second carbon material having the powder resistivity as described above are used in combination.

The powder resistance ratio R2 / R1 can be adjusted by changing the type, particle size, specific surface area, and / or aspect ratio of each carbon material.

As the first carbon material, for example, at least one selected from the group consisting of graphite, hard carbon, and soft carbon is preferable. In particular, the first carbon material preferably contains at least graphite. The second carbon material preferably contains at least carbon black. When these carbon materials are used, the powder resistivity ratio R2 / R1 can be easily adjusted.

The ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material incorporating the conductivity improver: S2 / S1 is, for example, 10 or more and 500 or less. From the viewpoint of suppressing the falling off of the positive electrode material, the specific surface area ratio S2 / S1 is preferably 10 or more and less than 300, more preferably 15 or more and 240 or less, and further preferably 55 or more and 240 or less. When the specific surface area ratio S2 / S1 is within the above range, the charging current at the time of overcharging is reduced. By adjusting the powder resistivity ratio R2 / R1 within the above range and adjusting the specific surface area ratio S2 / S1 within the above range, the falling off of the positive electrode material is further suppressed.

The average aspect ratio of the first carbon material incorporating the conductivity improver is, for example, 1 or more and 200 or less. The average aspect ratio of the first carbon material is preferably 1 or more and 100 or less, more preferably 1 or more and 35 or less, and further preferably 1.5 or more and 30 or less. When the average aspect ratio of the first carbon material is 1.5 or more and 30 or less, the low temperature and high rate performance is improved. This is because when the average aspect ratio of graphite is 1.5 or more and 30 or less, the effect of improving the conductivity in the c-axis direction of graphite by inserting the conductivity improver between the layers of graphite is further enhanced. It is considered that this is because the conductivity of the active material in contact with the plane perpendicular to the c-axis direction of graphite is further improved. From the viewpoint of improving low temperature and high rate performance, the average aspect ratio of the first carbon material is more preferably 6 or more and 25 or less.

The content of the first carbon material in the negative electrode electrode material is, for example, 0.05% by mass or more and 3.0% by mass or less, preferably 0.1% by mass or more and 2.0% by mass or less, and more preferably. Is 0.4% by mass or more and 2.0% by mass or less. When the content of the first carbon material in the negative electrode electrode material is 0.05% by mass or more, the effect of suppressing sulfation can be further enhanced. When the content of the first carbon material in the negative electrode material is 3.0% by mass or less, the effect of suppressing the falling off of the positive electrode material can be further enhanced.

The content of the second carbon material in the negative electrode electrode material is, for example, 0.03% by mass or more and 3.0% by mass or less, preferably 0.05% by mass or more and 1.0% by mass or less, and more preferably. Is 0.05% by mass or more and 0.5% by mass or less. When the content of the second carbon material in the negative electrode material is 0.03% by mass or more, the effect of suppressing the falling off of the positive electrode material can be further enhanced. When the content of the second carbon material in the negative electrode electrode material is 3.0% by mass or less, the effect of suppressing sulfation can be further enhanced.
The content of each carbon material in the negative electrode electrode material is determined by the procedure (B-1) described later.

The method for determining or analyzing the physical properties of the carbon material will be described below. It is assumed that the first carbon material described in (B) below incorporates a conductivity improver.
(B) Analysis of carbon material (B-1) Separation of carbon material A fully charged lead-acid battery is disassembled, a ready-made negative electrode plate is taken out, sulfuric acid is removed by washing with water, and vacuum drying (under pressure lower than atmospheric pressure). To dry). Next, the negative electrode material is collected from the dried negative electrode plate and pulverized. To 5 g of the pulverized sample, 30 mL of a 60 mass% nitric acid aqueous solution is added, and the sample is heated at 70 ° C. Further, 10 g of disodium ethylenediaminetetraacetate, 30 mL of aqueous ammonia having a concentration of 28% by mass, and 100 mL of water are added, and heating is continued to dissolve the soluble component. The sample thus pretreated is collected by filtration. The collected sample is sieved with a mesh size of 500 μm to remove components having a large size such as a reinforcing material, and the components that have passed through the sieve are recovered as a carbon material.

When the recovered carbon material is sieved wet using a sieve having an opening of 32 μm, the material remaining on the sieve without passing through the sieve mesh is used as the first carbon material and passes through the sieve mesh. The material is used as the second carbon material. That is, the particle size of each carbon material is based on the size of the mesh opening of the sieve. For wet sieving, see JIS Z8815: 1994.

Specifically, the carbon material is placed on a sieve having a mesh size of 32 μm, and the sieve is gently shaken for 5 minutes while sprinkling ion-exchanged water for sieving. The carbon dioxide material remaining on the sieve is recovered from the sieve by pouring ion-exchanged water over the sieve and separated from the ion-exchanged water by filtration. The second carbon material that has passed through the sieve is recovered by filtration using a membrane filter (opening 0.1 μm) made of nitrocellulose. The recovered first carbon material and second carbon material are each dried at a temperature of 110 ° C. for 2 hours. As the sieve having an opening of 32 μm, a sieve having a sieve net having a nominal opening of 32 μm specified in JIS Z 8801-1: 2006 is used.

The content of each carbon material in the negative electrode electrode material is determined by measuring the mass of each carbon material separated by the above procedure and calculating the ratio (mass%) of this mass to 5 g of the pulverized sample. Ask.

(B-2) Powder Resistance of Carbon Material The powder resistance R1 of the first carbon material and the powder resistance R2 of the second carbon material are the first carbon material and the first carbon material separated by the procedure of (B-1) above. For each of the two carbon materials, 0.5 g of a sample was put into a powder resistance measurement system (MCP-PD51 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and at a pressure of 3.18 MPa, JIS K 7194: 1994 was added. It is a value measured by a four-probe method using a compliant low resistance resistance meter (Loresta-GX MCP-T700, manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

(B-3) Specific Surface Area of Carbon Material The specific surface area S1 of the first carbon material and the specific surface area S2 of the second carbon material are the BET specific surface areas of the first carbon material and the second carbon material, respectively. The BET specific surface area is determined by using the BET formula by the gas adsorption method using each of the first carbon material and the second carbon material separated in the procedure (B-1) above. Each carbon material is pretreated by heating in a nitrogen flow at a temperature of 150 ° C. for 1 hour. Using the pretreated carbon material, the BET specific surface area of each carbon material is determined by the following equipment under the following conditions.
Measuring device: TriStar3000 manufactured by Micromeritix Co., Ltd.
Adsorption gas: Nitrogen gas with a purity of 99.99% or more Adsorption temperature: Liquid nitrogen boiling point temperature (77K)
Calculation method of BET specific surface area: Compliant with 7.2 of JIS Z 8830: 2013

(B-4) Average Aspect Ratio of First Carbon Material The first carbon material separated by the above procedure (B-1) is observed with an optical microscope or an electron microscope, and 10 or more arbitrary particles are selected. , Take a magnified photo of it. Next, the photograph of each particle is image-processed to obtain the maximum diameter d1 of the particle and the maximum diameter d2 in the direction orthogonal to the maximum diameter d1, and the aspect ratio of each particle is calculated by dividing d1 by d2. Ask. The average aspect ratio is calculated by averaging the obtained aspect ratios.

Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described for each of the main constituent requirements, but the present invention is not limited to the following embodiments.
(Negative electrode plate)
The negative electrode plate of a lead-acid battery contains a negative electrode material. The negative electrode plate is usually composed of a negative electrode lattice (negative electrode current collector) and a negative electrode material. The negative electrode material is a negative electrode plate obtained by removing the negative electrode current collector.

The negative electrode material preferably contains a negative electrode active material (lead or lead sulfate) that develops a capacity by a redox reaction. 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 material includes a carbon material and a conductivity improver incorporated into at least a part of the carbon material. The negative electrode material may further contain various additives such as an organic shrinkage proofing agent and barium sulfate. As the organic shrinkage proofing agent, a known material such as lignin (lignin sulfonic acid or a salt thereof) may be used.

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.

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 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, for example, lead powder, a carbon material, and various additives such as an organic shrink proofing agent, and kneading them. At the time of aging, it is preferable to ripen the unchemicald negative electrode plate at a temperature higher than room temperature and high humidity.

Using a non-chemical negative electrode plate, a ready-made negative electrode plate is obtained by chemical conversion. The chemical formation produces spongy lead. The chemical formation may be an electric tank chemical formation or a tank chemical formation. The electric tank chemical formation is 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. Tank chemical formation is performed before assembling the lead-acid battery or the electrode plate group.

In the step of producing the unchemical negative electrode plate, a carbon material containing a conductivity improver in advance may be added to the negative electrode paste. A known electrochemical method or chemical method may be used for incorporating the conductivity improver into the carbon material. Under normal operating conditions of lead-acid batteries (potential range of the negative electrode during charging and discharging), the conductivity improver is not electrochemically incorporated into the carbon material.

(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. 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 is a positive electrode material filled in a plurality of porous tubes, a core metal inserted in each tube, a current collector connecting the core metal, and a tube in which the core metal is inserted. And a collective punishment for connecting a plurality of tubes. The core metal and the current collector that connects the core metal are collectively called a positive electrode current collector.

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. As the core metal, a Pb-Ca-based alloy, a Pb-Sb-based alloy, or the like is used.

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.

(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. The thickness and the number of separators interposed between the negative electrode plate and the positive electrode plate may be selected according to the distance between the electrodes.

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 (polyester fiber such as polyolefin fiber, acrylic fiber, polyethylene terephthalate fiber, etc.), pulp fiber and the like can be used. Of these, glass fiber is preferable. 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.

On the other hand, 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 and / or oil, etc.) is extruded into a sheet and then pore-formed. It is obtained by removing the agent to form pores. The microporous membrane is preferably composed of a material having acid resistance, and preferably contains a polymer component as a main component. As the polymer component, polyolefins such as polyethylene and polypropylene are preferable.

The separator may be composed of, for example, only a non-woven fabric or only a microporous membrane. Further, the separator may be, if necessary, a laminate of a non-woven fabric and a microporous film, a material obtained by laminating different or similar materials, or a material in which irregularities are engaged with different or similar materials.

(Electrolytic solution)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may be gelled if necessary. A specific gravity at 20 ° C. of the electrolytic solution in lead-acid battery in a fully charged state after the conversion is, for example, 1.10~1.35g / cm ^3, it is preferable that 1.20~1.35g / cm ^3.

FIG. 1 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 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 sealed with a lid 15 having 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 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 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 ear portions 2a of the plurality of negative electrode plates 2 in parallel is connected to the penetrating connection body 8, and the ear portions of the plurality of positive electrode plates 3 are connected. The positive electrode shelf 5 that connects 3a in parallel 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.

The lead-acid batteries according to one aspect of the present invention are summarized below.
(1) One aspect of the present invention is a lead storage battery.
The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution.
The negative electrode plate is a lead-acid battery containing a carbon material and a negative electrode material containing a conductivity improver incorporated into at least a part of the carbon material.

(2) In the above (1), the carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm.
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material incorporating the conductivity improver: R2 / R1 is preferably more than 150.

(3) In the above (1) or (2), the carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm.
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material incorporating the conductivity improver: R2 / R1 is preferably 1200 or less.

(4) In any one of the above (1) to (3), the carbon material comprises a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm. Including
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material incorporating the conductivity improver: S2 / S1 is preferably 15 or more.

(5) In any one of the above (1) to (4), the carbon material comprises a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm. Including
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material incorporating the conductivity improver: S2 / S1 is preferably 240 or less.

(6) In any one of the above (1) to (5), the carbon material comprises a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm. Including
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The average aspect ratio of the first carbon material incorporating the conductivity improver is preferably 1.5 or more.

(7) In any one of the above (1) to (6), the carbon material comprises a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm. Including
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The average aspect ratio of the first carbon material incorporating the conductivity improver is preferably 30 or less.

(8) In any one of the above (1) to (7), the conductivity improver preferably contains at least one of _{an alkali metal and AsF 5.}

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 battery A1 >>
(1) Preparation of Negative Electrode Plate Lead powder, water, dilute sulfuric acid, barium sulfate, organic shrink-proofing agent, and carbon material are mixed to obtain a negative electrode paste. The negative electrode paste is filled in the mesh portion of the expanded lattice made of a Pb-Ca—Sn alloy, and aged and dried to obtain an unchemicald negative electrode plate. Graphite (average particle size D ₅₀ : 110 μm) is used as the carbon material. Lithium is previously inserted between the layers of graphite by an electrochemical method.

(2) Preparation of positive electrode plate A positive electrode paste is prepared by kneading lead powder, water, and sulfuric acid. The positive electrode paste is filled in the mesh portion of the expanded lattice made of a Pb-Ca—Sn alloy, and aged and dried to obtain an unchemicald positive electrode plate.

(3) Preparation of Lead-acid Battery The unchemicald negative electrode plate is housed in a bag-shaped separator formed of a polyethylene microporous film, and each cell consists of 5 unchemicald negative electrode plates and 4 unchemicald positive electrode plates. Form a group of plates. The six electrode plates are inserted into a polypropylene electric tank, an electrolytic solution is injected, and chemical formation is carried out in the electric tank. In this way, a liquid lead-acid battery having a nominal voltage of 12 V is produced. The nominal capacity of lead-acid batteries is 30 Ah (5-hour rate).

The content of the carbon material (graphite) in the negative electrode material is 1.0% by mass. By the procedure described above, it is confirmed that the carbon material (graphite) incorporates lithium by using the X-ray diffraction method. The lithium content in the negative electrode material obtained by the procedure described above is about 0.001% by mass. The average aspect ratio of the carbon material (graphite) obtained by the procedure described above is about 11.

<< Lead-acid battery B1 >>
A lead-acid battery is produced in the same manner as the lead-acid battery A1 except that the carbon material does not take in lithium.

The following evaluations are made for each lead-acid battery.
[Evaluation 1: Accumulation of lead sulfate after PSOC cycle life test]
Perform the following PSOC cycle life test.
After performing the first discharge for 59 seconds with the first current and the second discharge for 1 second with the second current at 25 ° C., charging for 60 seconds with a voltage of 14 V (maximum current 100 A) is performed. The first current shall be a value obtained by multiplying 0.05 CA by 18.3. The second current is 300A. This is set as one cycle and charging / discharging is repeated. Rest for 40-48 hours every 3600 cycles. After 40,000 cycles, the fully charged battery is disassembled, the negative electrode plate is taken out, washed with water, and vacuum dried (dried under a pressure lower than atmospheric pressure). Then, the negative electrode material is separated from the negative electrode plate, and the accumulated amount of lead sulfate (the mass ratio of lead sulfate to the negative electrode material) is determined.

[Evaluation 2: Amount of loss of positive electrode material (positive electrode active material) after PSOC cycle life test]
From the battery disassembled above, the positive electrode plate is further taken out, washed with water, and dried. Then, the positive electrode material is separated from the positive electrode plate, and the mass Mb of the positive electrode material after the life test is obtained.
The fully charged battery before the life test is disassembled, and the mass Ma of the positive electrode material before the life test is obtained by the same method as described above. Using Ma and Mb, the amount of dropout of the positive electrode material is calculated from the following formula.
Amount of dropout (mass%) of positive electrode material = (Ma-Mb) / Ma × 100

The evaluation results are shown in Table 1.

In the lead-acid battery A1 using a carbon material incorporating lithium, the amount of lead sulfate accumulated is significantly reduced as compared with the lead-acid battery B1 using a carbon material not incorporating lithium. However, in the lead-acid battery A1, the amount of the positive electrode material dropped off increases.

<< Lead-acid batteries C1 to C10 >>
As the carbon material, carbon black (average particle size D ₅₀ : 40 nm) is used together with graphite (average particle size D _{50: 110 μm).} In advance, lithium is inserted between the layers of graphite by an electrochemical method. Other than the above, a lead-acid battery is produced and evaluated in the same manner as the lead-acid battery A1.

In the lead-acid batteries C1 to C10, the content of the first carbon material contained in the negative electrode electrode material is 1.0% by mass, and the content of the second carbon material is 0.3% by mass. However, these values are obtained when the negative electrode plate of the produced lead-acid battery is taken out and the carbon material contained in the negative electrode electrode material is separated into the first carbon material and the second carbon material by the procedure described above. It is a value obtained as the content of each carbon material contained in the electrode material (100% by mass). Further, the powder resistivity ratios R2 / R1 obtained by the above-mentioned procedure are the values shown in Table 2. The specific surface area ratio S2 / S1 obtained by the procedure described above is 15 to 240. The average aspect ratio of the first carbon material obtained by the procedure described above is about 11.

By the procedure described above, it is confirmed by the X-ray diffraction method that the first carbon material incorporates lithium. The lithium content in the negative electrode material obtained by the procedure described above is about 0.001% by mass.
The evaluation results are shown in Table 2.

In the lead storage batteries C1 to C10, the amount of lead sulfate accumulated is reduced. In the lead-acid batteries C3 to C7 in which the powder resistivity ratio R2 / R1 is in the range of 150 or more and 1200 or less, the falling off of the positive electrode material is suppressed. In particular, in the lead-acid batteries C5 to C7 in which the powder resistivity ratio R2 / R1 is in the range of 550 or more and 1050 or less, the amount of the positive electrode material dropped off is reduced to less than 15% by mass.

In the lead-acid batteries C8 to C10 having a powder resistivity ratio R2 / R1 of more than 1200, the amount of the positive electrode material falling off increases. It is considered that this is because gas generation becomes active at an early stage of charging, and the positive electrode material is likely to fall off with the gas generation.

<< Lead-acid batteries D1 to D9 >>
A lead-acid battery is produced and evaluated in the same manner as the lead-acid battery C6 except that the specific surface area ratio S2 / S1 is set to the value shown in Table 3. The powder resistivity ratio R2 / R1 is about 830. The average aspect ratio of the first carbon material is 1.5 to 30.
The evaluation results are shown in Table 3.

In the lead storage batteries D1 to D9, the amount of lead sulfate accumulated is reduced. In the lead-acid batteries D3 to D7 in which the powder resistivity R2 / R1 is in the range of 150 or more and 1200 or less and the specific surface area ratio S2 / S1 is in the range of 10 or more and less than 300, the falling off of the positive electrode material is suppressed. To. In the lead-acid batteries D4 to D7 in which the specific surface area ratio S2 / S1 is in the range of 15 or more and 240 or less, the amount of the positive electrode material falling off is further suppressed.

<< Lead-acid batteries E1 to E10 >>
A lead-acid battery is produced in the same manner as the lead-acid battery C6 except that the average aspect ratio of the first carbon material is set to the value shown in Table 4. The powder resistivity ratio R2 / R1 is about 830. The specific surface area ratio S2 / S1 is 15 to 240.

<< Lead-acid battery F1 >>
A lead-acid battery is produced in the same manner as the lead-acid battery E6 except that the first carbon material does not take in lithium.

For the batteries of the lead-acid batteries E1 to E10 and the lead-acid battery F1, the amount of lead sulfate accumulated is determined by the same procedure as in the above evaluation 1, and the following evaluation is performed.

[Evaluation 3: Low temperature and high rate performance]
At −15 ° C., discharge at 6.25 CA until the terminal voltage reaches 6 V, and the discharge time at this time is calculated. This discharge time is used as an index of low temperature and high rate performance. It is expressed as a ratio when the result of the lead storage battery F1 is 100.
The evaluation results are shown in Table 4.

In the lead storage batteries E1 to E10, the amount of lead sulfate accumulated is reduced. In the lead-acid batteries E2 to E9 in which the average aspect ratio of the first carbon material is in the range of 1.5 or more and 30 or less, the low temperature and high rate performance is improved. In particular, in the lead storage batteries E5 to E8 in which the average aspect ratio of the first carbon material is in the range of 6 or more and 25 or less, excellent low temperature and high rate performance of 102 or more can be obtained.

The lead-acid battery according to one aspect of the present invention can be applied to a control valve type and a liquid type lead-acid battery, such as a power source for starting an automobile or a motorcycle, an industrial power storage device such as an electric vehicle (forklift, etc.), and the like. Can be suitably used as a power source for

1 Lead storage battery 2 Negative electrode plate 2a Negative electrode plate ear 3 Positive electrode plate 4 Separator 5 Positive electrode shelf 6 Negative electrode shelf 7 Positive electrode pillar 8 Penetration connector 9 Negative electrode pillar 11 Electrode group 12 Electrode tank 13 Partition 14 Cell chamber 15 Lid 16 Negative electrode terminal 17 Positive electrode terminal 18 Liquid spout

Claims (4)

It ’s a lead-acid battery,
The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution.
The negative electrode plate is seen containing a carbon material, a negative electrode material containing a conductivity enhancing agent incorporated into at least a portion of the carbon material,
A lead-acid battery in which the conductivity improver is lithium. The carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm.
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The first aspect of claim 1, wherein the ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material incorporating the conductivity improver: R2 / R1 is 150 or more and 1200 or less. Lead-acid battery. The carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm.
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The first or second claim, wherein the ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material incorporating the conductivity improver: S2 / S1 is 15 or more and 240 or less. Lead-acid battery. The carbon material includes a first carbon material having a particle size of 32 μm or more and a second carbon material having a particle size of less than 32 μm.
The conductivity improver is incorporated into the first carbon material, and is incorporated into the first carbon material.
The lead-acid battery according to any one of claims 1 to 3, wherein the first carbon material incorporating the conductivity improver has an average aspect ratio of 1.5 or more and 30 or less.

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