JP2022109137A - Control valve type lead-acid storage battery - Google Patents

Abstract

To provide a control valve type lead-acid storage battery that can suppress occurrence of a stratification phenomenon of electrolytic solution and has excellent cycle life performance.SOLUTION: A control valve type lead-acid storage battery comprises: an electrolyzer having a plurality of cell chambers partitioned by partition walls; a plurality of electrode plate groups that are stored in the plurality of cell chambers, respectively; and electrolytic solution injected in the plurality of cell chambers. The electrode plate groups are composed of a plurality of positive electrode plates and negative electrode plates disposed alternately and separators disposed between the positive electrode plates and the negative electrode plates. The positive electrode plates are composed of a positive electrode collector and positive electrode active material filled in the positive electrode collector; the negative electrode plates are composed of a negative electrode collector and negative electrode active material filled in the negative electrode collector. A ratio Mp/Mn of mass Mp of the positive electrode active material to mass Mn of the negative electrode active material per cell chamber after formation is equal to or larger than 1.30 and equal to or smaller than 1.65. A ratio Ms/Mp of mass Ms of pure sulfuric acid contained in the electrolytic solution to the mass Mp of the positive electrode active material per cell chamber after the formation is equal to or larger than 0.30 and equal to or smaller than 0.40.

Description

The present invention relates to a valve-regulated lead-acid battery.

In a valve-regulated lead-acid battery, the oxygen gas generated at the positive electrode during overcharging is consumed at the negative electrode and returned to water, making it possible to seal the battery. A lead-acid battery equipped with a valve that operates at a predetermined pressure to release to the outside.

The electrolyte in a valve-regulated lead-acid battery is non-fluidized, and exists only to the extent that it impregnates the separator and the electrode plates. Therefore, in the valve-regulated lead-acid battery, the stratification phenomenon that the sulfuric acid generated from the electrode plate during charging sinks to the bottom of the battery case and the sulfuric acid specific gravity of the electrolyte increases toward the bottom of the battery case occurs. It is thought to be difficult to occur, but when charging and discharging are repeated in a relatively small amount of overcharge, the stratification phenomenon of the electrolyte tends to occur, especially in valve-regulated lead-acid batteries used for cycle applications , the stratification phenomenon of the electrolytic solution causes a decrease in capacity, which may lead to the end of life.

In addition, when a valve regulated lead-acid battery having a container with a long height and a short width is used vertically, stratification of the electrolyte tends to occur. When the electrolyte stratification phenomenon occurs, the high-concentration electrolyte tends to cause sulfation in which lead sulfate enlarges on the surface of the negative electrode plate in the lower part of the battery case where the concentration of the electrolyte is high.

When sulfation occurs, the release of sulfuric acid from the negative electrode active material is suppressed, so the charge acceptance of the lower portion of the negative electrode plate decreases, and the charge/discharge reaction proceeds mainly in the upper portion of the negative electrode plate. The softening of the positive electrode active material on the upper portion of the positive electrode plate facing the upper portion and the corrosion of the substrate made of a lead alloy as a current collector progresses, and the life of the lead-acid battery ends early.

Japanese Patent Application Laid-Open No. 2003-36831 JP 2013-41757 A

As a method for solving the above problems, it has been conventionally performed to add silica fine particles to the electrolytic solution. Disclosed is a valve-regulated lead-acid battery having an electrolytic solution to which a gel electrolyte solution containing 0% by mass or less of phosphoric acid and dilute sulfuric acid containing less than 10% by mass of fine silica particles is added.

However, although the valve-regulated lead-acid battery disclosed in Patent Document 1 can improve the initial capacity and cycle life performance, it requires a large amount of silica fine particles, and as a result, the electrolytic solution gels before injection. As a result, it may become difficult to inject the electrolytic solution. Moreover, since the amount of silica fine particles added is large, it is disadvantageous in terms of cost.

Further, in Patent Document 2, an internal space is formed in which the ratio H/W between the dimension H in the height direction of the container and the dimension W in the width direction parallel to the electrode plate surface is 1.7 or more. , and a lead-acid battery in which the negative electrode plate has a negative electrode active material containing 0.016% by mass or more of antimony after formation is disclosed. It is disclosed that liquid stratification can be suppressed and excellent cycle life performance can be obtained.

However, in the lead-acid battery disclosed in Patent Document 2, the negative electrode active material contains antimony, the hydrogen overvoltage is lowered, the electrolysis reaction of water is promoted, and more gas is generated during charging. Although the stratification phenomenon can be suppressed, the amount of the electrolyte decreases, that is, so-called liquid depletion may occur, and the cycle life performance may decrease.

Therefore, as a result of various studies, the present inventors determined that the ratio between the mass of the positive electrode active material and the mass of the negative electrode active material and the ratio between the mass of the positive electrode active material and the mass of pure sulfuric acid contained in the electrolytic solution are defined. The inventors have found that the stratification phenomenon can be suppressed and the cycle life performance can be improved, leading to the present invention.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a valve-regulated lead-acid battery having excellent cycle life performance.

A valve-regulated lead-acid battery according to an aspect of the present invention includes a container having a plurality of cell chambers partitioned by partition walls, a plurality of electrode plate groups housed in the plurality of cell chambers, and The electrode plate group is composed of a plurality of positive electrode plates and negative electrode plates alternately arranged, and a separator disposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate comprises: A valve-regulated lead-acid battery comprising a positive electrode current collector and a positive electrode active material filled in the positive electrode current collector, and a negative electrode plate comprising a negative electrode current collector and a negative electrode active material filled in the negative electrode current collector. and the ratio M _p /M _n of the mass M _p of the positive electrode active material to the mass M _n of the negative electrode active material per cell chamber after chemical conversion is 1.30 or more and 1.65 or less, and the cell after chemical conversion The gist is that the ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolyte to the mass M _p of the positive electrode active material per chamber is 0.30 or more and 0.40 or less.

ADVANTAGE OF THE INVENTION The valve-regulated lead-acid battery which concerns on this invention can suppress the stratification phenomenon of electrolyte solution, and has the outstanding cycle life performance.

An embodiment of the present invention will be described. The embodiment described below is an example of the present invention, and the present invention is not limited to this embodiment. In addition, various modifications or improvements can be added to the present embodiment, and forms to which such modifications or improvements are added can also be included in the present invention.

A valve-regulated lead-acid battery according to the present invention comprises a container having a plurality of cell chambers partitioned by partition walls, a plurality of electrode plate groups housed in the plurality of cell chambers, and a and an electrolytic solution. The electrode plate group includes a plurality of positive electrode plates and negative electrode plates alternately arranged, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive current collector. The negative electrode plate is composed of a negative electrode current collector and a negative electrode active material filled in the negative electrode current collector.

Also, a lid having openings for pouring and exhausting liquid is welded or adhered to the battery case, and the electrolytic solution is poured through the openings. In addition, a valve element that operates at a predetermined pressure to release oxygen gas to the outside when the internal pressure of the battery rises due to oxygen gas generated at the positive electrode plate during overcharging is provided in the lid opening for liquid injection and exhaust. (control valve) is provided.

The electrode plate group of the valve-regulated lead-acid battery according to the present invention includes a plurality of positive electrode plates and negative electrode plates alternately arranged, and a separator disposed between the positive electrode plate and the negative electrode plate. It includes a positive electrode plate, a negative electrode plate, and a glass fiber mat (separator). Further, the number of positive plates constituting the electrode plate group may be one more than the number of negative plates, or the number of negative plates may be one more than the number of positive plates. and the number of negative plates may be the same. The shape of the separator may be sheet-like, bag-like, or U-shaped. When using a bag-shaped or U-shaped separator for accommodating the electrode plate, the positive electrode plate may be accommodated, or the negative electrode plate may be accommodated.

The ears of each positive electrode plate in the electrode plate group are integrally connected by a positive electrode strap, the ears of each negative electrode plate are integrally connected by a negative electrode strap, and the positive electrode strap and the negative electrode strap of adjacent cell chambers are connected to each other by a battery container. are adjacent to each other via a partition wall, and are connected through a through-hole provided in the partition wall. In addition, the positive electrode pillar protrudes upward from the positive electrode strap in the cell chamber at one end of the battery case, and the negative electrode pillar projects upward from the negative electrode strap in the cell chamber at the other end of the battery container. is set.

Next, the valve-regulated lead-acid battery according to the present invention will be described in detail.

[Ratio _Mp / _Mn of the mass _Mp of the positive electrode active material to the mass _Mn of the negative electrode active material per cell chamber after chemical conversion]
The ratio _Mp / _Mn of the mass _Mp of the positive electrode active material to the mass _Mn of the negative electrode active material per cell chamber after formation of the valve-regulated lead-acid battery according to the present invention is 1.30 or more and 1.65 or less. With this, a sufficient amount of the positive electrode active material is retained in the positive electrode plate, thereby exhibiting excellent life performance. Furthermore, the ratio M _p /M _n is preferably 1.40 or more and 1.55 or less, and within this range, remarkably excellent cycle life performance can be obtained.

When the ratio M _p /M _n is less than 1.30, the amount of the positive electrode active material is small relative to the amount of the negative electrode active material, the electrolysis of water during charging increases, a large amount of oxygen gas is generated from the positive electrode, and the negative electrode Oxygen gas is incompletely consumed at the end of the battery, and the oxygen gas is released to the outside of the battery, resulting in a decrease in the amount of the electrolyte solution. In addition, when charging and discharging are repeated, since the amount of the positive electrode active material is small relative to the amount of the negative electrode active material, the softening of the positive electrode active material is likely to progress, which may lead to the falling off of the positive electrode active material and decrease the cycle life performance. . On the other hand, when the ratio M _p /M _n exceeds 1.65, the amount of the positive electrode active material is large relative to the amount of the negative electrode active material, charging is limited by the negative electrode, the positive electrode is insufficiently charged, and oxygen gas is generated from the positive electrode. Since the amount of is reduced, the stratification phenomenon of the electrolytic solution is likely to occur, and excellent cycle life performance cannot be obtained.

The ratio M _p /M _n can be adjusted, for example, by the following method.
A positive electrode active material to be applied to a positive electrode current collector when manufacturing a positive electrode plate through a process of applying a kneaded product (active material paste) containing lead powder, sulfuric acid, water, and a predetermined additive to a positive electrode current collector. is adjusted so that the ratio M _p /M _n is 1.30 or more and 1.65 or less. In addition, when manufacturing the negative electrode plate, the filling amount of the negative electrode active material applied to the negative electrode current collector is reduced so that the ratio M _p /M _n is adjusted to 1.30 or more and 1.65 or less. However, in order to obtain the desired discharge capacity, it is preferable to adjust the ratio M _p /M _n by increasing or decreasing the filling amount of the positive electrode active material.
The number of positive plates and negative plates included in the electrode plate group may be adjusted by appropriately changing the configuration of the number of positive plates and negative plates, or the lattice shape of the current collector.

[Ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolytic solution to the mass M _p of the positive electrode active material per cell chamber after chemical conversion]
The ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolytic solution to the mass M _p of the positive electrode active material per cell chamber after formation of the valve-regulated lead-acid battery according to the present invention is 0.30 or more. When it is 0.40 or less, a sufficient amount of sulfuric acid is supplied to the positive electrode active material, so excellent life performance is exhibited. Furthermore, the ratio M _s /M _p is preferably 0.32 or more and 0.38 or less. Within this range, remarkably excellent cycle life performance can be obtained.
In this specification, "pure sulfuric acid" means sulfuric acid contained in the electrolytic solution.

If the ratio M _s /M _p is less than 0.30, the amount of pure sulfuric acid contained in the electrolytic solution is insufficient with respect to the amount of the positive electrode active material, leading to a decrease in capacity, and the desired discharge capacity cannot be obtained. On the other hand, when the ratio M _s /M _p exceeds 0.40, the amount of pure sulfuric acid contained in the electrolytic solution is large relative to the amount of the positive electrode active material, and stratification tends to occur. In addition, since a large amount of sulfuric acid is supplied to the positive electrode active material, softening of the positive electrode active material is likely to progress, causing the positive electrode active material to come off, thereby deteriorating the cycle life performance.

The ratio M _s /M _p can be adjusted, for example, by the following method.
When manufacturing the positive electrode plate through the step of applying a kneaded product (positive electrode active material paste) containing lead powder, sulfuric acid, water and a predetermined additive to the positive electrode current collector, the positive electrode active material applied to the positive electrode current collector The filling amount of the substance is adjusted so that the ratio M _s /M _p is 0.30 or more and 0.40 or less. Further, when the electrolytic solution made of dilute sulfuric acid is injected into each cell chamber, the specific gravity of the injected electrolytic solution is reduced so that the ratio M _s /M _p is 0.30 or more and 0.40 or less. Although it can be adjusted, it is preferable to adjust the ratio M _s /M _p by increasing or decreasing the filling amount of the positive electrode active material in order to obtain the desired discharge capacity.

[Calculation of ratio M _p /M _n and ratio M _s /M _p ]
“M _s ”, “M _p ” and “M _n ” in the ratio M _p /M _n and the ratio M _s /M _p in this specification are calculated by the following three equations.
Formula 1; “M _s ” = (“mass of positive electrode plate, negative electrode plate and separator soaked with electrolytic solution per cell chamber” − “mass of dried positive electrode plate, negative electrode plate and separator per cell chamber” + “ Mass of surplus liquid") x "concentration of sulfuric acid in electrolyte (mass%)"
Equation 2: “M _p ”=“mass of dried positive electrode plate per cell chamber”−“mass of dried positive electrode current collector per cell chamber”
Formula 3: “M _n ”=“mass of dried negative electrode plate per cell chamber”−“mass of dried negative electrode current collector per cell chamber”
Using the obtained "M _s ", "M _p " and "M _n " calculated by the above three equations, the ratio M _p /M _n and the ratio M _s /M _p can be obtained.

The "mass of the positive electrode plate, the negative electrode plate and the separator soaked with the electrolyte per cell chamber" in the above formula 1 means the positive electrode plate, the negative electrode plate and the separator contained in the electrode plate group accommodated in any one cell chamber. is the sum of the masses of all the positive electrode plates, negative electrode plates and separators included in the electrode plate group soaked with the electrolytic solution injected into the cell chamber.
"The mass of the positive electrode plate, negative electrode plate and separator after drying per cell chamber" means that the positive electrode plate, negative electrode plate and separator are washed with water to remove the sulfuric acid in the electrolyte solution and completely dried in a vacuum state. It is the sum of the masses of the positive electrode plate, the negative electrode plate and the separator.
The "mass of surplus liquid" is the mass of the electrolyte that remains in the cell chamber without permeating into the positive electrode plate, the negative electrode plate, or the separator included in the electrode plate group.
The "concentration (% by mass) of sulfuric acid in the electrolyte" can be calculated from the specific gravity of the electrolyte. The specific gravity of the electrolyte can be measured by squeezing out the electrolyte permeated into the separator included in the electrode group and using neutralization titration. If there is an excess liquid, the "concentration of sulfuric acid in the electrolyte (% by mass)" may be calculated from the specific gravity of the excess liquid.

In addition, the "mass of the positive electrode plate after drying per cell chamber" in the above formula 2 is the measurement of the "mass of the positive electrode plate, the negative electrode plate and the separator after drying per cell chamber" used in the calculation of " _Ms ". It is the total weight of the positive electrode plate completely dried in a vacuum, which is actually obtained. In addition, the “mass of positive electrode current collector per cell chamber” refers to the positive electrode current collector obtained by separating the positive electrode active material from the positive electrode plate used for measuring the mass of the positive electrode plate after drying. It is the total value of the completely dried positive electrode current collector mass.

Furthermore, the “mass of the dried negative electrode plate per cell chamber” in the above formula 3 is the measurement of the “mass of the dried positive electrode plate, the negative electrode plate and the separator per cell chamber” used in the calculation of “M _s ”. It is the total weight of the negative electrode plate completely dried in a vacuum, which is actually obtained. In addition, the “mass of the negative electrode current collector per cell chamber” refers to the negative electrode current collector obtained by separating the negative electrode active material from the negative electrode plate used for measuring the mass of the negative electrode plate after drying. It is the total value of the completely dried negative electrode current collector mass.
For the values used in the above three formulas, the values after formation are adopted.

[Positive plate]
The positive electrode plate is composed of a positive current collector made of lead or a lead alloy and a positive electrode active material filled in the positive current collector. The positive electrode current collector can be obtained, for example, by forming lead or a lead alloy into a grid shape by a continuous casting method, a book molding method, an expanding method, a punching method, or the like.

Lead alloys forming the positive electrode current collector include, for example, lead-calcium alloys and lead-calcium-tin alloys. In particular, calcium (Ca) is 0.02 mass% or more and 0.09 mass% or less, tin (Sn) is 0.4 mass% or more and 2.5 mass% or less, aluminum (Al) is 0.005 mass% or more and 0 In the case of a lead alloy having a composition of 0.04% by mass or less and the balance being lead and unavoidable impurities, it is possible to improve both the corrosion resistance and the mechanical strength of the positive electrode current collector.

Addition of Ca improves the mechanical strength of the positive electrode current collector. If the content of Ca is less than 0.02% by mass, the effect is small, and if it exceeds 0.09% by mass, corrosion resistance may decrease. The addition of Sn improves the fluidity of the molten lead alloy and improves the mechanical strength of the positive electrode current collector. If the Sn content is less than 0.4% by mass, the effect is small, and if it exceeds 2.5% by mass, the corrosion resistance may decrease. Addition of Al prevents the loss of Ca due to oxidation of the molten metal, and further improves the mechanical strength of the positive electrode current collector. If the amount of Al added is less than 0.005% by mass, the effect is small, and if it exceeds 0.04% by mass, Al tends to precipitate as dross.

In addition, the density of the positive electrode active material after chemical conversion is preferably 4.2 g/cm ³ or more and 4.9 g/cm ³ , so that a valve-regulated lead-acid battery with well-balanced cycle life performance and discharge capacity can be obtained. can be done. More preferably, the density of the positive electrode active material after chemical conversion is 4.4 g/cm ³ or more and 4.9 g/cm ³ or more, and furthermore, the density of the positive electrode active material after chemical conversion is 4.6 g/cm ³ or more. More preferably, it is 4.9 g/cm ³ .

The density of the positive electrode active material after chemical conversion can be adjusted, for example, by the following method. Water injected during kneading of the positive electrode active material paste when manufacturing the positive electrode plate through the step of applying a kneaded product (positive electrode active material paste) containing lead powder, sulfuric acid, water, and a predetermined additive to a current collector. in a state where the lead powder held in the current collector by the chemical conversion is changed to lead dioxide, and the density of the positive electrode active material after chemical conversion of the positive electrode mixture is 4.2 g / cm ³ or more and 4.9 g / cm Adjust to ³ or less.
Also, the density of the positive electrode active material after chemical conversion of the positive electrode mixture can be measured by, for example, the Archimedes method or the mercury intrusion method.

[Negative plate]
The negative plate includes a negative current collector made of lead or a lead alloy, and a negative active material filled in the negative current collector. The negative electrode current collector can be obtained by forming lead or a lead alloy into a lattice by a book molding method, an expanding method, a punching method, or the like. The lead alloy forming the negative electrode current collector and its composition are not particularly limited, but it is preferable to use the same lead alloy as that used for the positive electrode current collector in consideration of handling in manufacturing.

The density of the negative electrode active material after chemical conversion is not particularly limited, but when it is 4.2 g/cm ³ or more and 4.9 g/cm ³ or less, a valve regulated lead-acid battery with excellent discharge capacity can be obtained.
The density of the negative electrode active material after chemical conversion can be measured by, for example, the Archimedes method or the mercury intrusion method.

[Electrolyte]
The electrolytic solution of the valve-regulated lead-acid battery according to the present invention may contain 0.5% by mass or more and less than 5.0% by mass of silica fine particles, and the sol-like silica fine particles are electrolyzed in the initial charge after injection. When the liquid temperature rises or the liquid is left standing, van der Waals bonds are formed between the oxygen of the silica fine particles and the hydrogen of the sulfuric acid in the electrolyte, resulting in gelation, and the electrolyte becomes non-fluid, further suppressing the stratification phenomenon. can do.

In addition, an electrolytic solution having a silica fine particle content of less than 0.5% by mass has a lower degree of gelation than an electrolytic solution having a silica fine particle content of 0.5% by mass or more and 5.0% by mass or less. The effect of liquefying is not sufficiently obtained. On the other hand, when the content of silica fine particles is 5.0% by mass or more, the electrolytic solution gels before injection, making it difficult to inject the electrolytic solution and increasing raw material costs.
An additive may be added to the electrolytic solution as appropriate. For example, an additive capable of improving charge acceptance, such as aluminum sulfate, potassium aluminum sulfate, or sodium aluminum sulfate, can be used.

[Battery]
The size of the battery case of the valve-regulated lead-acid battery according to the present invention is not particularly limited, but considering the desired discharge capacity and the actual use of the valve-regulated lead-acid battery, the height of the battery case relative to the width dimension W of the battery case is It is preferable that the ratio H/W of the length dimension H is 0.5 or more and 3.0 or less.

In this specification, the "width dimension W of the battery case" is the width dimension of the outer shape of the battery case. If the bottom of the container is square, it is defined as the dimension of one side of the outer bottom of the container. The "height dimension H of the battery case" is the height dimension of the outer shape of the battery case, and is defined as the height dimension from the outer bottom surface of the battery case to the welded portion between the battery case and the lid.

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples.
[Preparation of test battery]
12V-24Ah valve regulated lead-acid batteries of Examples 1 to 5 and Comparative Examples 1 to 4 were produced using a battery case having an outer shape of 175 mm in length, 166 mm in width and 95 mm in height. The ratio H/W of the height dimension H of the battery case to the width dimension W of the battery case is 0.57.

(Examples 1 to 3, Comparative Example 1 and Comparative Example 2)
First, a positive electrode plate and a negative electrode plate were produced as follows.
A plate-like current collector made of a lead-calcium-tin-based lead alloy was cast, and ears were formed at predetermined positions of the plate-like current collector. The positive electrode current collector is made of a lead alloy having a composition of 0.055% by mass of calcium, 2.00% by mass of tin, 0.02% by mass of aluminum, and the balance being lead and inevitable impurities, The negative electrode current collector was made of a lead alloy having a composition of 0.09 mass % calcium, 0.50 mass % tin, 0.02 mass % aluminum, and lead and unavoidable impurities.

Next, lead powder containing lead monoxide as a main component was kneaded with water and dilute sulfuric acid, and if necessary, additives were mixed and kneaded to produce a positive electrode active material paste. Similarly, lead powder containing lead monoxide as a main component was kneaded with water and dilute sulfuric acid, and if necessary, additives were mixed and kneaded to produce a negative electrode active material paste. In addition, the manufacturing process of the positive electrode and negative electrode active material pastes was carried out by the usual method of kneading lead powder, sulfuric acid, water and predetermined additives. By adjusting the amount of water added, the density of the positive electrode active material and the density of the negative electrode active material after chemical conversion can be adjusted.

Next, a positive electrode plate and a negative electrode plate before anodization were produced by performing a step of filling the positive electrode current collector and the negative electrode current collector with the active material paste, a preheating drying step, and an aging drying step. Each step was performed by a normal method. In addition, by adjusting the filling amount of the positive electrode active material paste in the process of filling the positive electrode current collector with the positive electrode active material paste, the positive electrode active material mass _Mn per cell chamber after chemical conversion is _1.30 in Example 1, _1.50 in Example 2, _1.65 in Example 3, 1.25 in Comparative Example 1, and 1 in Comparative Example 2. .70. In addition, the ratio M _s /M _p of the mass M _s of the pure sulfuric acid contained in the electrolytic solution to the mass M _p of the positive electrode active material per cell chamber after chemical conversion is also adjusted in the same manner as the ratio M _p /M _n . , the ratio M _s /M _p of Examples 1 to 3 and Comparative Examples 1 and 2 was set to 0.34.

Next, the positive electrode plate and the negative electrode plate before anodization were immersed in an anodization tank in which the specific gravity of sulfuric acid was previously adjusted to 1.080 (converted value at 20° C.), and the tank anodization was performed by an ordinary method. After that, the positive electrode plate and the negative electrode plate were pulled up from the anodization tank, and the positive electrode plate and the negative electrode plate after the anodization were produced by performing a washing process and a drying process.

Next, the obtained positive electrode plates and negative electrode plates after chemical conversion were alternately laminated via a sheet-like glass fiber mat to obtain an electrode plate group of 5 positive electrode plates and 6 negative electrode plates.
Next, using a COS (cast-on-strap) type casting apparatus, straps and intermediate poles or terminal poles were formed on the positive electrode plate and the negative electrode plate of each electrode plate group.
Six of these electrode plate groups were prepared and placed in each cell chamber of the container, resistance welding of the intermediate electrode column between adjacent cell chambers, heat welding of the container and lid, and insertion from the injection port into each cell chamber. After performing the usual steps of injecting the electrolyte and closing the injection port with a liquid plug, etc., the initial charging step was performed. A storage battery was produced. Sulfuric acid having a specific gravity of 1.308 (converted at 20° C.) and a concentration of 40.4% by mass was used as the electrolyte, and 242 mL of the electrolyte was injected per cell chamber.

(Example 4, Example 5, Comparative Example 3 and Comparative Example 4)
In the valve regulated lead-acid batteries of Examples 4, 5, Comparative Examples 3 and 4, the ratio M _s /M _p was 0.30 in Example 4, 0.40 in Example 5, and 0.40 in Comparative Example 3. was adjusted to 0.25 in , and 0.45 in Comparative Example 4. Valve regulated lead-acid batteries of Examples 4, 5, Comparative Examples 3 and 4 were obtained in the same manner as in Example 2 except for the above points.

[Measurement of ratio M _p /M _n and ratio M _s /M _p after chemical conversion]
The ratio M _p /M _n and the ratio M _s /M _p of the obtained valve-regulated lead-acid batteries of Examples 1 to 5 and Comparative Examples 1 to 4 after formation were investigated using the following three equations. The values to be substituted into the following three equations are included in the electrode plate group housed in the randomly selected cell chamber after disassembling the valve-regulated lead-acid batteries of Examples 1 to 5 and Comparative Examples 1 to 4. The positive electrode plate, the negative electrode plate, the separator, and the electrolytic solution injected into the cell chamber were measured by the following method.
Formula 1; “M _s ” = (“mass of positive electrode plate, negative electrode plate and separator soaked with electrolytic solution per cell chamber” − “mass of dried positive electrode plate, negative electrode plate and separator per cell chamber” + “ Mass of surplus liquid") x "concentration of sulfuric acid in electrolyte (mass%)"
Formula 2; “M _p ”=“mass of dried positive electrode plate per cell chamber”−“mass of dried positive electrode current collector per cell chamber”)
Formula 3: “M _n ”=“mass of dried negative electrode plate per cell chamber”−“mass of dried negative electrode current collector per cell chamber”

First, in each example and each comparative example, an electrode plate group housed in a randomly selected cell chamber was taken out, and the electrolyte soaked into the glass fiber mat (separator) contained in the electrode plate group was squeezed out, The specific gravity of the electrolytic solution was measured by neutralization titration with an aqueous sodium hydroxide solution, and the "concentration (% by mass) of sulfuric acid in the electrolytic solution" was calculated from the obtained specific gravity. If there is surplus liquid that has not soaked into the positive electrode plate, the negative electrode plate, and the glass fiber mat (separator) contained in the electrode plate group housed in the cell chamber, the specific gravity of the surplus liquid is measured, and the obtained specific gravity is , the "concentration of sulfuric acid in the electrolyte (% by mass)" may be calculated.

Next, the masses of five positive electrode plates (after chemical conversion), six negative electrode plates (after chemical conversion), and glass fiber mats (separators) soaked with the electrolytic solution, which are included in the electrode plate group taken out, are measured. The total value was taken as "the mass of the positive electrode plate, the negative electrode plate and the separator per cell chamber permeated with the electrolyte". In addition, when there is surplus liquid, the "mass of surplus liquid" is also measured.
After that, the positive electrode plate (after chemical conversion), the negative electrode plate (after chemical conversion), and the glass fiber mat (separator) soaked with the electrolytic solution whose mass was measured were all washed with water to remove the sulfuric acid in the electrolytic solution, and then vacuumed. Dry (completely dry) for 12 hours or more in a dryer, measure the mass of the dried positive electrode plate, negative electrode plate and glass fiber mat (separator), and calculate the total value as "the positive electrode plate after drying per cell chamber. , the mass of the negative electrode plate and the separator”. In order to calculate “M _p ” and “M _n ”, the “mass of dried positive electrode plate per cell chamber” and the “mass of dried negative electrode plate per cell chamber” were also measured.

Furthermore, the current collector obtained by separating the active material from the dried 5 positive electrode plates and 6 negative electrode plates was washed, dried (completely dried) for 12 hours or more in a vacuum dryer, and after drying The mass of the positive electrode current collector and the negative electrode current collector are measured, and the respective total values are calculated as “the mass of the dried positive electrode current collector per cell chamber” and “the mass of the dried negative electrode current collector per cell chamber.” "
The values obtained from these measurement results were substituted into the above three equations to calculate the ratio M _p /M _n and the ratio M _s /M _p of each example and each comparative example.

[Test and Evaluation]
Further, for the valve regulated lead-acid batteries of Examples 1 to 5 and Comparative Examples 1 to 4, one more valve regulated lead-acid battery of each level was produced in the same manner, and the ratio M _p /M _n and the ratio M _s / The following tests were performed assuming that M _p was substantially the same as that measured.
First, an initial capacity test was performed by discharging to a final voltage of 10.2 V at an ambient temperature of 25° C. and a discharge current of 0.25 C ₂₀ A to confirm the initial discharge capacity.
Next, discharge at a discharge current of 0.25 C ₂₀ A for 2 hours, charge at a charge current of 0.25 C ₂₀ A and a constant voltage of 14.7 V for 6 hours, repeat this 50 times, and then rest for 24 hours. Then, a cycle life test was performed again, in which one cycle was a discharge step in which the battery was discharged to a final voltage of 10.2 V at a discharge current of 0.25 C ₂₀ A and a recovery charge step. In the case of the discharging process, if the discharge duration is 2 hours or more, the charging/discharging process is performed again, and then the discharging process is performed. On the other hand, when the discharge duration is less than 2 hours, it is determined that the life has been reached, and the number of cycles performed up to that time is taken as the battery life. The specific gravity of the electrolyte solution was measured in the lower part, and the difference in specific gravity between the upper and lower parts was calculated from these measured values.

The results of these tests are shown in Table 1. Judgment in Table 1 is based on condition A that the upper and lower specific gravity difference of the electrolyte solution is 0.01 or less, condition B that the life performance (number of cycles) is 2000 cycles or more, and initial discharge capacity that is 24 Ah or more. When all of the conditions C and C are satisfied, the ◯ mark is shown. In addition, when any one of condition A, condition B, or condition C is not satisfied, it is indicated by an X mark.

From the evaluation results shown in Table 1, the ratio _Mp / _Mn of the mass _Mp of the positive electrode active material to the mass _Mn of the negative electrode active material per cell chamber after formation is 1.30 or more and 1.65 or less, and The valve-controlled lead of Examples 1 to 3 in which the ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolyte to the mass M _p of the positive electrode active material per cell chamber after chemical conversion is 0.34. It can be seen that the storage battery has a small difference in specific gravity between the upper and lower sides, can suppress the stratification phenomenon, has an improved number of cycles, and has the desired discharge capacity.

On the other hand, in the valve-regulated lead-acid battery of Comparative Example 1 in which the ratio M _p /M _n is 1.25, the difference in specific gravity between the upper and lower sides is small, but the number of cycles is not improved. This is because the amount of the positive electrode active material is less than the amount of the negative electrode active material, the electrolysis of water during charging increases, a large amount of oxygen gas is generated from the positive electrode, and the consumption of oxygen gas at the negative electrode becomes incomplete. This is thought to be caused by so-called liquid depletion, in which oxygen gas is released to the outside of the battery and the amount of electrolyte decreases. In addition, when charging and discharging were repeated, the amount of the positive electrode active material was smaller than the amount of the negative electrode active material, so the softening of the positive electrode active material was likely to proceed, causing the positive electrode active material to fall off, and the cycle life performance to deteriorate. be done.
Further, in the valve-regulated lead-acid battery of Comparative Example 2 in which the ratio M _p /M _n is 1.70, the difference in specific gravity between the upper and lower sides is large, indicating that the number of cycles is not improved. This is because the amount of the positive electrode active material is larger than that of the negative electrode active material, charging is limited at the negative electrode, the positive electrode becomes insufficiently charged, and the amount of oxygen gas generated from the positive electrode decreases, so the stratification phenomenon of the electrolyte occurs. It is considered that this is because the cycle life performance has deteriorated due to the fact that it is more likely to occur.

Next, the ratio M _p /M _n of the mass M _p of the positive electrode active material to the mass M _n of the negative electrode active material per cell chamber after chemical formation is 1.50, and the mass M p of the positive electrode active material per cell chamber after chemical conversion is Valve regulated leads of Examples 2, 4 and 5 in which the ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolyte to the mass M _p is 0.30 or more and 0.40 or less It can be seen that the storage battery has a small difference in specific gravity between the upper and lower sides, can suppress the stratification phenomenon, has an improved number of cycles, and has the desired discharge capacity.

In contrast, the valve-regulated lead-acid battery of Comparative Example 3, in which the ratio M _s /M _p was 0.25, had a small initial discharge capacity. It is considered that this is because the amount of pure sulfuric acid contained in the electrolytic solution was insufficient with respect to the amount of the positive electrode active material, and the discharge capacity decreased.
Further, in the valve-regulated lead-acid battery of Comparative Example 4 in which the ratio M _s /M _p is 0.45, the difference in specific gravity between the upper and lower sides is large, indicating that the number of cycles is not improved. This is because the amount of pure sulfuric acid contained in the electrolyte solution is large relative to the amount of the positive electrode active material, so the stratification phenomenon is likely to occur, and the amount of sulfuric acid supplied to the positive electrode active material is large, so the positive electrode active material is easily softened. , leading to detachment of the positive electrode active material, leading to deterioration in cycle life performance.

Therefore, the ratio M _p /M _n of the mass M _p of the positive electrode active material to the mass M _n of the negative electrode active material per cell chamber after formation is 1.30 or more and 1.65 or less, and A valve-regulated lead-acid battery in which the ratio M _s /M _p of the mass M _s of pure sulfuric acid contained in the electrolyte to the mass M _p of the positive electrode active material is 0.30 or more and 0.40 or less, the stratification of the electrolyte It was confirmed that the sintering phenomenon could be suppressed and excellent cycle life performance was obtained.

Claims (4)

a battery container having a plurality of cell chambers partitioned by partition walls; a plurality of electrode plate groups respectively housed in the plurality of cell chambers; and an electrolytic solution injected into the plurality of cell chambers,
The electrode plate group includes a plurality of positive electrode plates and negative electrode plates alternately arranged, and a separator disposed between the positive electrode plate and the negative electrode plate,
The positive electrode plate comprises a positive electrode current collector and a positive electrode active material filled in the positive electrode current collector,
In a valve-regulated lead-acid battery in which the negative electrode plate comprises a negative electrode current collector and a negative electrode active material filled in the negative electrode current collector,
A ratio M _p /M _n of the mass M _p of the positive electrode active material to the mass M _n of the negative electrode active material per cell chamber after chemical conversion is 1.30 or more and 1.65 or less,
The ratio M _s /M _p of the mass M _s of the pure sulfuric acid contained in the electrolytic solution to the mass M _p of the positive electrode active material per cell chamber after chemical conversion is 0.30 or more and 0.40 or less. Characteristic valve-regulated lead-acid battery. 2. The valve regulated lead-acid battery according to claim 1, wherein the density of the positive electrode active material after chemical conversion is 4.2 g/cm ³ or more and 4.9 g/cm ³ or less. The lead alloy of the positive electrode current collector contains 0.02% to 0.09% by mass of calcium, 0.4% to 2.5% by mass of tin, and 0.005% to 0.005% by mass of aluminum. 3. The valve-regulated lead-acid battery according to claim 1, wherein the composition is 04% by mass or less and the balance is lead and unavoidable impurities. 4. The electrolytic solution according to any one of claims 1 to 3, wherein the electrolytic solution contains silica fine particles, and the content of the silica fine particles in the electrolytic solution is 0.5% by mass or more and less than 5% by mass. valve-regulated lead-acid battery.