JP3376017B2 - Lead acid battery with sulfuric acid concentration sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead storage battery equipped with a sulfuric acid concentration sensor for detecting the concentration of sulfuric acid as an electrolytic solution.

[0002]

2. Description of the Related Art Sulfuric acid is widely used industrially, and it is often necessary to know the concentration of sulfuric acid when using it. Therefore, measuring the sulfuric acid concentration is very significant industrially. For example, in a lead-acid battery, the sulfuric acid concentration changes as it is charged and discharged as shown in Chemical Formula 2 below. Therefore, the amount of charge and discharge of the lead-acid battery can be measured by measuring the sulfuric acid concentration. Further, if it can be easily measured, it is possible to control the charge / discharge electric quantity of the lead storage battery. During charge / discharge of a lead-acid battery, the sulfuric acid concentration usually changes in the range of about 8 to 45%, so measurement in this concentration range is particularly important.

[0003]

[Chemical 2]

Most lead acid batteries are used for starting automobiles, but when the state of charge is insufficient, the remaining capacity is insufficient and the lead acid battery cannot be started. It was very inconvenient because the driver could not know such a situation in advance. If the state of charge is known in advance, it is possible to take measures such as supplementary charging before the vehicle stops. Therefore, a lead storage battery provided with a sensor capable of knowing the charge / discharge amount has been strongly demanded.

Further, the current generator controls the charging current at the end of charging with the charging voltage, but since the charging voltage is a value that changes depending on the temperature, the history of the battery, etc., the control appropriate for the battery should be performed. I can't. On the contrary,
The concentration of the electrolytic solution accurately represents the charge / discharge amount. Therefore,
According to the concentration of the electrolytic solution, the end of charging can be accurately grasped, and charging control suitable for the battery can be performed. From this, there has been a strong demand for a lead storage battery equipped with a sensor capable of knowing the charge / discharge amount based on the concentration of the electrolytic solution.

However, conventionally, the methods shown in the following (1) to (4) are known as methods for measuring the concentration of the electrolytic solution. It could not be put to practical use as a battery sensor. (1) Refractive index measuring method This is a method of measuring using the property that the refractive index of sulfuric acid changes depending on its concentration. Since it is composed of a light emitting diode, a light receiving diode, and an optical path, it cannot be a small and inexpensive sensor, and has been put to practical use in stationary lead acid batteries, but has not been put to practical use in automobile lead acid batteries. (2) Specific gravity measurement method This method measures the specific gravity of sulfuric acid using a float. Although it is an inexpensive and convenient method, there are many cost and structural difficulties in incorporating it into the control system as an electric signal.
In addition, measurement was impossible unless the system was sufficiently rich in sulfuric acid. (3) Electrochemical method This is a method in which an electrode system for a sensor composed of metal / sulfuric acid / metal oxide is separately provided, and the electromotive force is measured by the sulfuric acid concentration dependence. There is no suitable one for this electrode system, and the one that has been realized has a drawback that it requires periodic regeneration of both electrodes. (4) Electric conductivity method This method measures the electric conductivity of sulfuric acid. It seems to be a simple method, but sulfuric acid has the maximum electric conductivity at a concentration of about 30%, so it is not possible to simply determine the sulfuric acid concentration from the electric conductivity, so complicated data processing is required, It is expensive.

On the other hand, the popularity of retainer type lead storage batteries in which a glass mat or the like is impregnated with an electrolytic solution has been increasing in recent years.
In this storage battery, since the electrolytic solution has no fluidity and the amount of the electrolytic solution is limited, there is no floating liquid at all. Therefore, even the above method cannot be used at all.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lead-acid battery having a sulfuric acid concentration sensor which has a simple structure and is inexpensive.

[0009]

The lead acid battery with a sulfuric acid concentration sensor of the present invention is a lead acid battery equipped with a sulfuric acid concentration sensor for detecting the concentration of sulfuric acid as an electrolytic solution, wherein the sulfuric acid concentration sensor reacts with sulfuric acid. And a sensor main body made of a polymer compound having a property of changing the conductivity in a monovalent function with a change in sulfuric acid concentration, and a lead wire for passing an electric current through the sensor main body, The sulfuric acid concentration sensor is configured to determine the conductivity of the sensor body, and the sulfuric acid concentration sensor is characterized in that the sensor body is provided in contact with the electrolytic solution.

The sensor body preferably does not occupy a large space in the lead acid battery, and is preferably a thin film-shaped one or a string-shaped insulating material coated on its surface. To be

The electrolytic solution of the lead storage battery may be in a gel state. Further, the lead storage battery may be of a retainer type, and in this case, the sensor main body is provided in a state of being sandwiched by the retainer. In particular, as described above, the sensor main body formed in a thin film shape, or the sensor main body formed in a state of covering the surface of the string-like insulator is absorbed by the elasticity of the retainer, and it has been impaired in appearance. Since it shows the same state as the absence, it is more preferably used in a retainer type lead storage battery.

The polymer compound is not particularly limited as long as it has a property of reacting with sulfuric acid and a property of changing its conductivity in a monovalent function with a change in sulfuric acid concentration. However, since the electrolytic solution of sulfuric acid has a certain degree of conductivity, it is necessary that the polymer compound has a considerably large conductivity.

As the polymer compound, specifically, a compound represented by the formula (I), a compound obtained by oxidizing a compound represented by the formula (I), or a compound represented by the formula (I) is used. A compound of formula (I)
Z is an aromatic hydrocarbon ring or an aromatic heterocycle, R is hydrogen, halogen, or another monovalent group, and n is an integer of 2 or more. These compounds are characterized by having a nitrogen atom which reacts with an acid in the molecule.

[0014]

[Chemical 3]

Examples of the aromatic heterocycle represented by Z in the formula (I) include those containing at least one of boron, nitrogen, oxygen, silicon, phosphorus, sulfur, germanium and selenium. To be Specific examples of Z in formula (I) include the following groups. That is, 1,4-phenylene group, 1,4-naphthylene group,
2,5-pyridinediyl group, 2,5-pyrrolediyl group, 2,5-thiophenyldiyl group and the like. In addition, these groups, as the side chain of the ring, an alkyl group, an alkoxy group,
It may have an amide group, a carboxyl group or the like.

Other monovalent groups for R in formula (I) include, for example, boron, carbon, nitrogen, oxygen, aluminum, silicon, phosphorus, sulfur, gallium, germanium,
Mention may be made of a monovalent group bonded to N in the formula (I) via any of arsenic, selenium, indium, tin, antimony, tellurium, thallium, lead, bismuth and transition metals. Specifically, the following groups can be mentioned. Alkyl group, alkenyl group, cycloalkyl group, cycloalkenyl group, aryl group, alkoxy group, aryloxy group,
Acyl group, thiolato group, carboxyl group, amino group, mercapto group, cyano group, carbonato group, amide group, carbonyl group, nitro group, aldehyde group, substituted amino group, alkynyl group, isocyanato group, isothiocyanato group, sulfonyl group, carbamoyl Group, imino group, imide group, imidoyl group, nitroso group, azido group, diazonium group,
Alkoxycarbonyl group, boryl group, silyl group, phosphino group, organometallic group, germyl group, seleno group, stannyl group, etc.

Examples of the above-mentioned polymer compounds include those represented by the formulas (II) to (VI). Note that n in the formula is an integer of 2 or more.

[0018]

[Chemical 4]

[0019]

[Chemical 5]

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

[Chemical 8]

For example, the polyaniline represented by the formula (II) is oxidized to obtain the emeraldine base type structure represented by the formula (VII), but it hardly conducts electricity. But,
When an acid is added to this, an emeraldonic acid type structure represented by the formula (VIII) is obtained, which exhibits a large conductivity of about 10 Scm ⁻¹ (Siemens per centimeter) (eg, F.-L.Lu et al. Journal of american
Chemical Society (Journal of Am
erican Chemical Societ
y) ”, 108, 8311, 1986: edited by Naoya Ogata,“ Conductive Polymer ”, published by Kodansha Scientific,
75, 1990: Ryuichi Yamamoto, Takeshi Matsunaga, "Polymer Battery", published by Kyoritsu Shuppan, 34, 1990). That is, the conductivity of these compounds changes with the addition of acid in sulfuric acid. In the formulas (VII) and (VIII), m and n are integers of 2 or more.

[0024]

[Chemical 9]

[0025]

[Chemical 10]

Further, for example, when the compound represented by the formula (III) is oxidized, it becomes an emeraldine base type analog structure represented by the formula (IX), and when an acid is added thereto, the emeraldine acid type structure represented by the formula (X) is obtained. It becomes a similar structure. Note that expression (IX),
In (X), m and n are integers of 2 or more.

[0027]

[Chemical 11]

[0028]

[Chemical 12]

Further, according to the purpose of controlling the acid addition reaction of the above-mentioned polymer compound, controlling the stability of the above-mentioned polymer compound in a sulfuric acid solution, etc., the above-mentioned polymer compound is mixed with other polymer compounds or ceramics. It may be used by coating with or the like. As other polymer compounds, polyolefins, vinyl compound polymers, vinylidene compound polymers, polyamides, polyesters, polyurethanes, polydienes, silicone resins, phenol resins, urea resins, melamine resins, polyimides, epoxy resins, polyethers, Polycarbonate, polyether sulfone, polyphenylene sulfide, polyphenylene ether, cellulose derivative, polyethyleneimine,
Vinyl compound copolymer, vinylidene copolymer, diene copolymer, cyclic olefin polymer, cyclic olefin copolymer, furan resin, ketone resin, polyvinyl alcohol, fluororesin, polyarylate, natural rubber derivative, π
Examples thereof include conjugated conductive polymers.

The current applied to the sensor body may be either direct current or alternating current depending on the purpose. The conductivity of the sensor body can be obtained by measuring the current value or electric resistance value flowing through the sensor body, that is, the polymer compound.

[0031]

The conductivity of the above-mentioned polymer compound corresponds to the sulfuric acid concentration. Therefore, if the conductivity of the sensor body is determined, the sulfuric acid concentration, that is, the concentration of the electrolytic solution will be determined. Therefore, in the lead storage battery provided with the sensor body, it is possible to control charging and discharging suitable for actual use.

As the above-mentioned polymer compound, a compound represented by the formula (I), a compound obtained by oxidizing a compound represented by the formula (I), or a compound obtained by quaternizing the compound represented by the formula (I) is obtained. When used with a compound that has a nitrogen atom that reacts with an acid in the molecule, a reaction with sulfuric acid occurs deterministically, a change in conductivity occurs clearly, and sulfuric acid concentration can be detected more accurately. Is possible.

In the above-mentioned polymer compound, the basicity of the polymer compound, the measuring range of the sulfuric acid concentration and the measuring sensitivity can be controlled by appropriately selecting the kind of the aromatic ring and the substituent. The sulfuric acid, which is the electrolytic solution, needs only to be immersed in the sensor body, and thus the present invention can be applied to a retainer type lead storage battery.

[0034]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to these examples. (Embodiment 1) FIG. 1 is a longitudinal sectional view showing a lead acid battery with a sulfuric acid concentration sensor according to this embodiment. DESCRIPTION OF SYMBOLS 1 is a battery case, 2 is a lid, 3 is a liquid port plug that closes the liquid injection port of the lid 2, 4 is an electrode plate group housed in the battery case 1, 5 is an electrolytic solution, 5a is a liquid surface of the electrolytic solution 5. Is. The liquid port plug 3 is provided with a cylindrical holding tube 31 extending vertically downward, and the sulfuric acid concentration sensor 10 is provided in the holding tube 31. Most of the holding tube 31 is provided so as to be immersed in the electrolytic solution 5. As shown in the enlarged view of FIG. 2, the sulfuric acid concentration sensor 10 includes a sensor body 11 and two platinum lead wires 12, and an electric current is passed through the sensor body 11 by a control unit (not shown) to cause the sensor body 1 to move.
The conductivity of 1 is measured. The sensor body 11 is a rectangular thin film and is installed at the lower end of the holding tube 31. The platinum lead wires 12 are connected to both ends of the sensor body 11 by the conductive carbon paste 13, extend upward in the holding tube 31 and are connected to the control section.

The sensor body 11 was formed as follows. First, aniline was oxidatively polymerized with ammonium peroxodisulfate in an aqueous solution containing sulfuric acid and hydrochloric acid to obtain a powdery polymer, which was treated with aqueous ammonia to obtain emeraldine base type polyaniline. Next, this polyaniline powder was dissolved in N-methylpyrrolidone, the resulting solution was spread on a substrate, and the solvent was evaporated under vacuum to remove it to obtain a thin film having a thickness of 90 μm. This thin film is 7.2m
Sensor body 11 by cutting it into a rectangle measuring m × 10.5 mm
Got Then, on the two shorter sides of the sensor body 11,
A platinum lead wire 12 (diameter 0.2 mm) was connected to each using a conductive carbon paste 13.

The lead acid battery having the above structure is 12V, 33Ah.
A sulfuric acid solution having a specific gravity of 1.28, that is, a concentration of about 40% is contained as the electrolytic solution 5 and is in a charged state. In this lead-acid battery, a DC voltage of 0.5 V, at which electrolysis of water is unlikely to occur, was applied between the two platinum lead wires 12, and the conductivity was measured.
It was m ^-1 . FIG. 3 shows changes in the terminal voltage (discharge voltage), the electrolyte concentration, and the conductivity of the sensor body 11 when the lead storage battery was discharged at a constant current of 4.8 A.

As can be seen from FIG. 3, the change in conductivity is approximately proportional to the change in electrolyte concentration, and the sensor main body 11
To obtain the electric conductivity of is to obtain the electrolytic solution concentration. The change in the conductivity and the concentration of the electrolytic solution and the change in the terminal voltage have a monovalent functional relationship. Therefore, when the conductivity of the sensor body 11 is obtained, the terminal voltage, that is, the charge / discharge amount is obtained.

The sulfuric acid concentration sensor 10 used in the lead-acid battery having the above-described structure includes a sensor body 11 and a platinum lead wire 12.
It is simple and inexpensive because it is simply configured with. Moreover, it is only necessary to apply an electric current to the sensor main body 11 to obtain the conductivity of the sensor main body 11, so that it is easy to use.

(Embodiment 2) The lead acid battery with a sulfuric acid concentration sensor of this embodiment is different from that of Embodiment 1 in that the sensor main body 11
The only difference is the composition of the others, and the others are the same.

The sensor main body 11 of this embodiment was formed as follows. That is, first, an emeraldine base type polyaniline powder was obtained in the same manner as in Example 1. Next, a polyaniline powder and a nylon 6 powder were dissolved in formic acid at a weight ratio of 3: 1, the resulting solution was spread on a substrate, and the solvent was evaporated under vacuum to remove the thin film having a thickness of 75 μm. Got The thin film was cut into a rectangle of 7.0 mm × 10.1 mm to obtain a sensor body 11. Nylon 6 is
Since the mechanical strength and the acid resistance are both high, the strength of the sensor main body 11 of this embodiment is improved.

FIG. 4 shows changes in the terminal voltage (discharge voltage), the electrolyte concentration, and the conductivity of the sensor body 11 when the lead storage battery was discharged at a constant current of 4.8 A.

As can be seen from FIG. 4, the change in conductivity is approximately proportional to the change in electrolyte concentration, and the sensor body 11
To obtain the electric conductivity of is to obtain the electrolytic solution concentration. The change in the conductivity and the concentration of the electrolytic solution and the change in the terminal voltage have a monovalent functional relationship. Therefore, when the conductivity of the sensor body 11 is obtained, the terminal voltage, that is, the charge / discharge amount is obtained.

(Embodiment 3) FIG. 5 is a vertical sectional view showing a lead acid battery with a sulfuric acid concentration sensor of this embodiment. 21 is a battery case
Reference numeral 21a is a partition wall that divides the inside of the battery case 21 into a plurality of chambers, 22 is a lid, 23 is a liquid port plug that closes the liquid injection port of the lid 22, and 24 is the battery case 2.
1 is a group of electrode plates housed in 1; 24a is a positive electrode plate;
b is a negative electrode plate. 26 is a strap for connecting the positive electrode plate 24a to an external terminal. Adjacent electrode plates 24a,
A film 27 made of a glass mat is provided between 24b. The membrane 27 is folded upward to form a double layer between the adjacent electrode plates 24a and 24b. Then, the membrane 27 is impregnated with the electrolytic solution, which limits the fluidity of the electrolytic solution, the amount of the electrolytic solution is very small, and the suspension is apparently completely absent. That is, the storage battery of this embodiment is of the retainer type.

In the storage battery having the above structure, the sulfuric acid concentration sensor 10 is sandwiched between the double portions of the membrane 27. That is, the sensor body 11 is sandwiched between the membranes 27 in parallel with the electrode plates 24a and 24b, and the platinum lead wire 12 penetrates the bent portion of the upper portion of the membrane 27 and is connected to the liquid port plug 23. . Since the thickness of the sensor main body 11 is only 0.2 mm, the thickness is absorbed by the elasticity of the film 27, which is no different from the appearance that it is not clogged. One sulfuric acid concentration sensor 10 is provided in one chamber partitioned by the partition wall 21a. The sensor body 11 is the same as that in the first embodiment.

The lead-acid battery having the above structure is 12 V, 33 Ah.
The membrane 27 is impregnated with a sulfuric acid solution having a specific gravity of 1.28 and is in a charged state. In this lead-acid battery, a DC voltage of 0.5 V, at which electrolysis of water is unlikely to occur, was applied between the two platinum lead wires 12, and the conductivity was measured to be 3.5 Scm ^−1. It was Furthermore,
It was 3.0 when measured after discharging at 4.8 V for 5 hours.
It was Scm ^-1 .

Also in this embodiment, the same operational effects as those of the first embodiment are obtained. That is, since the sensor body 11 is in contact with the electrolyte solution of the membrane 27, the charge / discharge amount can be obtained by obtaining the conductivity of the sensor body 11 as in the first embodiment. In addition, it has a simple structure, is inexpensive, and is easy to use.

Since the sensor main body 11 is used by sandwiching it in the membrane 27, it is desirable that the sensor main body 11 be permeable to the electrolytic solution, particularly sulfate ion. For example, a porous film,
A sheet having fine pores such as a woven cloth is suitable.

(Embodiment 4) The lead acid battery with a sulfuric acid concentration sensor of this embodiment has a sensor main body 11 which is different from that of the embodiment 3.
Other than that, the composition and composition are the same.

The sensor body 11 of this embodiment was formed as follows. That is, first, an emeraldine base type polyaniline powder was obtained in the same manner as in Example 1. On the other hand, at the tips of the two platinum lead wires 12 that are the same as in Example 3,
As shown in FIG. 6, a string portion 12a connecting both ends is provided.
The string portion 12a is made of nylon 6 and has a length of 4 mm and a diameter of 0.2 mm. Next, the polyaniline powder was dissolved in N-methylpyrrolidone, the string portion 12a was dipped in the obtained solution, and the periphery of the string portion 12a was coated with the solution. Then, the solvent is evaporated under vacuum to remove the solvent, and the sensor main body 11
Got That is, the sensor body 11 of the present embodiment is the cord portion 1
It is formed so as to cover the surface of 2a. The coating layer had a thickness of 0.05 mm.

Since the nylon 6 constituting the string portion 12a has high acid resistance, there is no problem even if it is used as a carrier of the sensor main body 11 immersed in the electrolytic solution, and since it is an insulator, It does not affect the change in conductivity of the sensor body 11.

The lead-acid battery with the sulfuric acid concentration sensor of this embodiment also exhibits the same effects as those of the third embodiment.

[0052]

As described above, the lead acid battery with the sulfuric acid concentration sensor of the present invention is equipped with the sulfuric acid concentration sensor 10 capable of determining the concentration of the electrolytic solution by determining the conductivity, so that the charge / discharge amount can be easily adjusted. You can know Moreover, since the sulfuric acid concentration sensor 10 is composed only of the sensor body 11, the platinum lead wire 12, etc., the structure is simple and inexpensive.

Further, since the sulfuric acid concentration sensor 10 can be used for a storage battery in which the electrolytic solution is in a gel state or a retainer type storage battery, it is possible to easily know the charge / discharge amount in a wide range of storage batteries.

As the polymer compound constituting the sensor main body 11, a compound represented by the formula (I) or a compound obtained by oxidizing the compound represented by the formula (I), or the formula (I)
When a compound obtained by quaternizing the compound represented by is used, since it has a nitrogen atom that reacts with an acid in the molecule,
The reaction with sulfuric acid takes place deterministically, and the change in conductivity is apparent. Therefore, the concentration of the electrolytic solution, that is, the charge / discharge amount can be known more accurately.

In the above polymer compound, the basicity of the polymer compound, the measuring range of the sulfuric acid concentration and the measuring sensitivity can be controlled by appropriately selecting the kind of the aromatic ring and the substituent. Therefore, the present invention can be applied to various lead storage batteries.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a lead acid battery with a sulfuric acid concentration sensor of Example 1.

FIG. 2 is a front view showing a sulfuric acid concentration sensor used in Examples 1, 2 and 3. FIG.

FIG. 3 is a diagram showing the lead-acid battery of Example 1 discharged at constant current,
It is a figure which shows the change of terminal voltage, electrolyte concentration, and electrical conductivity.

[Fig. 4] Fig. 4 is a diagram showing the lead-acid battery of Example 2 discharged with constant current,
It is a figure which shows the change of terminal voltage, electrolyte concentration, and electrical conductivity.

FIG. 5 is a vertical cross-sectional view showing a lead acid battery of Example 3.

6 is a front view showing a sulfuric acid concentration sensor used in Example 4. FIG.

[Explanation of symbols] 10 Sulfuric acid concentration sensor 11 Sensor body 12 Platinum lead wire 27 Membrane (Retainer)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Aya Nishino 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation (56) References JP-A-5-10908 (JP, A) JP-A-7- 72114 (JP, A) JP 60-112266 (JP, A) JP 4-93646 (JP, A) JP 62-42047 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/48 G01R 31/36 G01N 27/00-27/24

Claims (6)

(57) [Claims] 1. A lead acid battery provided with a sulfuric acid concentration sensor for detecting the concentration of sulfuric acid as an electrolytic solution, wherein the sulfuric acid concentration sensor has a property of reacting with sulfuric acid and changes with the change of the sulfuric acid concentration. A sensor body made of a polymer compound having a property of changing conductivity in a valence function, and a lead wire for passing an electric current through the sensor body are provided, and the concentration of sulfuric acid is obtained by obtaining the conductivity of the sensor body. A lead acid battery with a sulfuric acid concentration sensor, characterized in that the sulfuric acid concentration sensor is provided with the sensor body in contact with the electrolytic solution. 2. The lead acid battery with a sulfuric acid concentration sensor according to claim 1, wherein the sensor body is formed in a thin film shape. 3. The lead acid battery with a sulfuric acid concentration sensor according to claim 1, wherein the sensor body is formed so as to cover the surface of the string-shaped insulator. 4. The lead acid battery with a sulfuric acid concentration sensor according to claim 1, wherein the electrolytic solution is in a gel state. 5. The lead acid battery with a sulfuric acid concentration sensor according to claim 1, wherein the electrolytic solution is held by a retainer, and the sensor main body is provided in a state of being sandwiched by the retainer. 6. The polymer compound is a compound represented by the formula (I), a compound obtained by oxidizing a compound represented by the formula (I), or a quaternized compound represented by the formula (I). The compound obtained is: In formula (I), Z is an aromatic heterocycle,
Element, nitrogen, oxygen, silicon, phosphorus, sulfur, germanium,
It contains at least one of selenium.
Ri, R represents hydrogen, halogen, or other a monovalent radical, n is an integer of 2 or more and is claim 1 sulfuric acid concentration sensor with a lead-acid battery according.