JPH02177260A - Closed type lead accumulator - Google Patents

Abstract

PURPOSE:To improve a utilizing factor of both of positive and negative electrode active materials, and to increase weight efficiency and volumetric efficiency by mixing a carbon whisker or a graphite whisker that the have electronic conductivity with at least either the positive or negative electrode active materials. CONSTITUTION:With at least either positive or negative electrode active materials, a carbon whisker or a graphite whisker that have electronic conductivity is mixed. Diameter of the whisker is defined as not more than 10mum, an aspect ratio is not less than 50, and a specific surface area is not less than 2m<2>/g. As for the amount of the whisker, 1-10wt.% for a ratio of a non-formed positive electrode active material, while for a formed one, 0.01-3wt.%, and for a negative electrode, 0.01-3wt.% in every case. The number of whisker is defined as not less than 1X10<9> per 1cm<3> of apparent volume of the active material.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a sealed lead acid battery.

Prior Art and its Problems As is well known, the capacity of lead-acid batteries is regulated by the positive and negative active materials and the amount of sulfur in the electrolyte.

In order to improve the active material utilization rate of a lead-acid battery of a constant volume or -hiro weight, the amount of the active material can be reduced to increase sulfur!
! Either the amount must be increased or a more concentrated sulfuric acid electrolyte must be used. However, increasing the utilization rate of the positive electrode active material not only accelerates the softening and falling off of the active material, but also accelerates lattice corrosion. This has the disadvantage that the cycle and 71ff-) life performance of the resulting battery is significantly shortened.

On the other hand, if the utilization rate of the negative electrode active material is increased, the active material monkey 7
It has the disadvantage that its resistance to corrosion is low and its lifespan is shortened.

By using a highly concentrated sulfuric acid electrolyte, it is possible to improve the volumetric efficiency and weight efficiency of the battery.

However, although this has a small effect on the positive electrode plate, the highly concentrated sulfuric acid electrolyte promotes corrosion of the negative electrode active material, resulting in a short battery life.

The electrode plates used in lead-acid batteries can be broadly classified into paste type and clad type. No matter which electrode plate is used, a large amount of electricity and time are required in the chemical conversion process for activating the unformed active material. In fact, the excess charge of this chemical formation process is
Ajl is necessary, and usually theoretically necessary, especially to activate the positive electrode active material! It carries 2 to 4 times more electricity than its air capacity. This is considered to be due to the fact that lead dioxide, which is a positive electrode active material, has low electronic conductivity, and the electronic conductivity between particles of the active material is maintained only by contact between the particles. That is, when forming the positive electrode plate, first the particles in contact with the current collector are oxidized and become lead dioxide. Next, the particles in contact with this lead dioxide are chemically formed, which is repeated to form a chemically formed electrode plate. Therefore, particles far away from the current collector are only chemically formed at the end of the chemical formation process. This means that during the chemical formation process, the density of the chemical formation current to the active material particles is initially high. , which means that the final stage is low, which makes the efficiency of the formation current even lower as a whole.In order to make formation easier, lead cp
b3o4) may be added to the unformed active material. This is simply because the amount of electricity required is reduced due to its advanced oxidation. Even if this is done, the formation will still start from the vicinity of the current collector, and the efficiency of the formation electricity will still be low as a whole. Red lead is expensive, and the disadvantage of higher price is greater than the advantage of being able to reduce the amount of electricity used for chemical conversion.

USF No. 4,631.241 proposes mixing graphite into the positive electrode active material and retaining an electrolyte between the layers to increase the pore volume and capacity of the positive electrode. Since graphite has electron conductivity, it is possible to connect active material particles in an electron conductive manner. However, the graphite shown here has a particle size of 34
In order to connect between active material particles as large as 0 u+,
There are too few of them. The number of active material particles per unit volume is calculated from the specific surface area, pore size distribution, etc. in the case of a positive electrode, lXl0
~fX10”*, for negative electrode, 1×10 to 1×10
It is estimated that the number of On the other hand, this 540p
When 1% of graphite with the size of The amount is too small.

In order to improve the bond between the active material particles or between the active material particles and the lattice, it is disclosed in JP-A-61-128466 and JP-A-54-1 that carbon fibers or electron conductive fibers are present within the active material. Publication No. 10574, JP-A-58-57
This is proposed in m/g No. 4 publication. Also, JP-A-49-1
No. 03155 proposes the presence of a carbon am or a metal whisker such as a ship. The carbon fiber proposed in Knee is disclosed in Japanese Patent Application Laid-open No. 54-1057 (
As stated in Publication No. 1 as having a diameter of 0.01 to 1.01111 J, the diameter is 10 to 1000 pm, and according to the tests conducted by the present inventors, the diameter is large and the surface area is small. Because the number of contacts with active material particles was small, it was not possible to maximize the characteristics of carbon and dramatically improve conductivity.

JP-A-49-J03135 discloses that in addition to such carbon fibers, "metal whiskers for ships, etc." are present. However, it is not clear how "metal whiskers such as lead" are obtained, what characteristics, dimensions, and forms they have, and since no equivalent material is available, it is difficult to fully evaluate their effects. The inventor, etc. cannot be confirmed.

211jI obtained by the inventors' chatter vibration method
When lead fibers with a diameter of 50 μm were mixed into the active material, the density of the active material became higher and the contact density was thought to be improved, but the utilization rate of the active material and charge acceptance decreased. In addition, Japanese Patent Application Laid-Open No. 61-45565 states, ``It is made by mixing polyolefin-based or polyester-based synthetic resin with carbon powder or acid-resistant metal powder.'' 1~
10PtpI conductive synthetic resin fibers are mixed into the active material. However, although the conductive synthetic resin fibers obtained in this way are sufficient for reinforcing the active material, the conductivity of the fibers themselves is insufficient to improve the electronic conductivity between the particles, and 1-1
Incorporation of 0 ptN fibers causes a decrease in the apparent density of the active material, so
The function of "improving the adhesion between the active material and the grid body of the b-0a alloy grid and preventing the formation of a barrier layer" could not be confirmed.

Further, in order to improve the charge acceptance of the negative electrode, it is widely practiced to add carbon black. in this case,
Carbon black mainly lowers the end-of-charge voltage. That is,
By reducing the hydrogen overvoltage of the negative electrode, the current flowing at the end of charging is increased. Carbon black is
The particle size is very small compared to the graphite mentioned above.

Therefore, adding as much as 0.2 wt S is sufficient to contact individual particles of active material.

However, in this case, since carbon black has no length, its role is merely to exist between active material particles. That is, it has never been possible to connect tens or hundreds of active material particles in parallel. The improvement in charge acceptability of the negative electrode due to the addition of carbon black is due to an increase in the charge front current by lowering the final charge voltage, and is not due to an increase in the flow of current to individual active material particles. . This means that a large current also flows to the positive electrode at the end of charging, which accelerates corrosion of the positive electrode grid due to an increase in the amount of overcharged air, so it is not a preferable method in terms of life performance. do not have. In this way, adding carbon black to the negative electrode does not essentially improve charge acceptance. ◇ Purpose of the Invention The present invention solves the above-mentioned conventional problems; ■ Improves the utilization rate of positive and negative active materials and has higher weight efficiency and volumetric efficiency than before; ■ Improves charge acceptance (charging efficiency) of positive and negative active materials; Has long life cycle and float life performance, ■ Improves resistance to corrosion and enables the use of higher concentration sulfur electrolytes, which allows for longer lifespans without sacrificing lifespan. The objective is to provide an inexpensive sealed lead-acid battery that has improved utilization efficiency, ■ greatly reduces the amount of electricity required for forming the positive electrode plate.

Structure of the Invention The present invention provides a positive electrode plate consisting of a current collector containing pure lead or a lead alloy and a positive electrode active material containing lead dioxide as a main component in close contact with the current collector,
The negative electrode plate consists of a current collector made of pure lead, Pb Oa thread lead alloy, or other antimony-free ship metal, and a negative electrode active material whose main component is sponge-like metal lead in close contact with the current collector, and the electrolyte is made of fine glass. It is absorbed and fixed in a porous separator made of vAm or ultrafine organic fibers, or fixed in a gel form with a gelling agent made of silica, organic polymer, etc., and is attached to at least one of the positive and negative active materials. Diameter 1
0μm or less, aspect ratio 50 or more, specific surface area 2d79
Carbon whiskers or graphite whiskers with an electron conductivity of 0.01 to 10 V to the active material
This is a sealed lead-acid battery characterized by a mixture of lead-acid batteries at a ratio of t.

Hereinafter, the details of the present invention will be explained with reference to Examples.

Example 1 Carbon whiskers 609 were uniformly dispersed in 9409 water using an ultra-high speed mixer. The carbon whiskers used here were produced from hydrocarbons using a vapor phase growth method. As shown in the electron micrograph in Figure 1, the diameter is approximately 0.05~0*8 pjN
Its length is about 10 to 100 m, and its aspect ratio is said to be about 100, which is long considering its extremely thin diameter. The density of this thing is 1
．． 96 Lie, and the electronic conductivity is 7 x 10-3Ω-
1, and according to the BK'r method, the specific surface area is 10 to 40
◎ To 170 watts of the carbon whisker dispersion prepared in this manner, lead oxide powder 10009 containing 30% metallurgy was added and kneaded, and then 75 cc of sulfuric acid with a specific gravity of 1.40 was gradually added dropwise. By continuing to cross-wire, we obtained a base tom for the positive electrode.

The same procedure was used to prepare the negative electrode base, except that a predetermined amount of lignin and barium sulfate were added to the carbon whisker dispersion)
B was prepared. Further, conventional positive electrode base) O and negative electrode paste D were obtained by the same operation except that carbon whiskers were not used.

Made of Pb-0a-8n alloy that does not contain antimony, the dimensional force is 58 x L67 x 3.3 (2,0)l.
&lI The paste was filled into a teal cast grid body by a conventional method. (0 indicates the negative electrode grid) The electrode plate filled with the paste was left standing in 10 (1 SRH) at 35° C. for 3 days to age and harden the paste.

Thereafter, it was dried at 50° C. for one day to obtain an unformed positive electrode plate O and negative electrode plates B and D.

The physical properties of the paste and the amount of unformed active material after drying were as shown in Table 1.

Table 1 Two positive electrode plates and 33 negative electrode plates are stacked together via a fine glass separator according to Patent No. 11272702 to form an electrode group, and the sealed lead acid battery X according to the present invention is constructed by storing it in a battery case. Conventional sealed lead-acid batteries Y were manufactured using electrode plates C and D according to the method. 45 cc of H2SO4 per cell was injected into this, and a safety valve was attached. Thereafter, batteries X and Y were obtained by chemical conversion in a battery container for about 30 hours at a constant current of 0.85. The results of investigating the capacity of this battery at various discharge currents (0.05 to 30) are shown in FIG. The results of calculating the active material utilization rate under the same conditions from this result are shown in FIG. Sealed lead-acid battery 2x and chemical f
At the time of cm, a battery 5x having a specific gravity of 1.350 was obtained. The 20 HR capacity of these batteries 2x and 3x and the conventional battery Y, as well as the weight efficiency and volumetric efficiency calculated from these, are as shown in Table 2.

Table 2 The results of an alternate charge/discharge life test of these batteries are shown in FIG.

The test conditions are as follows.

0.250 FM, F, V, 1 every 50 cycles
．． A 700V/7* capacity test was conducted.

Example 3 A clad pipe in which a glass fiber woven fabric tube was inserted through a core made of a Pb-0a-8n alloy that does not contain antimony.
0 (not added) to the positive electrode active material.

Conventional example), 0.5 = 1-0.1-5 e 3.0-
An unformed clad positive electrode plate was prepared by filling lead oxide powder to which graphite whiskers were added at a concentration of 5 to 0 wt %.

One unformed positive electrode plate and two conventional negative electrode plates were combined and placed in each tank. Next, chemical formation was carried out in sulfuric acid having a specific gravity of 1.10 at a current of 1 μm/1 per positive electrode plate. The positive electrode plate was taken out at regular intervals and subjected to a discharge test to determine the ease with which the positive electrode plate was chemically formed. The results are shown in FIG.

The horizontal axis in FIG. 5 indicates the theoretical amount of formed electricity calculated from the amount of unformed positive electrode active material in percentage.

That is, 100% indicates the minimum amount of electricity required for chemical formation.

Example 4 As a conventional negative electrode plate, negative electrode plate E was prepared by adding carbon black in a weight ratio of 0.5 to the active material of the negative electrode plate of Example 1. The specific surface area of this carbon black was 1500'/y.

A conventional sealed lead acid battery 2 was obtained by combining the negative electrode plate E and the positive electrode plate C.

Using the sealed lead-acid battery X according to the present invention and the conventional sealed lead-acid battery Y and two batteries, 0.0001 to 0.
The battery was charged at a constant current of 50 μm, and the relationship between charging current and battery voltage was investigated. The results are shown in FIG.

The graphite whiskers used in Example 3 were carbon whiskers that were heat-treated at 3000°C, and although their size did not change much, their electronic conductivity was 5X.
It is 10-3Ω-1, which is one order of magnitude higher than that of carbon whiskers.

It is clear from Example 1 that the sealed lead-acid battery according to the present invention has a high active material utilization rate and high weight efficiency and volume efficiency. The number of positive electrode active material particles per unit volume is 1×10 to I
It has already been stated that the number is estimated to be 9 to 1×10 13 pieces. As shown in Example 1, the number of whiskers is estimated to be 1×10 to 1×10 15 when about 1% of the whiskers are added to the active material. Furthermore, since the whiskers have a large aspect ratio, it is estimated that the number of active material particles that come into contact with one whisker is 50 to 1000. Therefore, for example, in the negative electrode, it is presumed that a plurality of carmen whiskers are in contact with one active material particle.

According to the present invention, particles that are far apart and have not conventionally been connected in an electronically conductive manner are connected in parallel. Therefore, current flows extremely easily not only during charging and discharging but also during the chemical formation process, resulting in high charge acceptance, larger discharge capacity, and extremely high chemical formation current efficiency. This is clear from Examples 1 and 3.

The negative electrode active material is reduced to a coarse crystalline sulfate by charging and discharging with a high-finess electrolytic solution or high temperature, and its capacity decreases.

On the other hand, not only lead-acid batteries with a large amount of flowing electrolyte, but even sealed lead-acid batteries with a small amount of electrolyte, due to repeated deep discharges, the electrolyte becomes more concentrated in the lower part and lower in the upper part. ification
).

The layering caused by the fact that the lower part of the negative electrode plate is usually far from the ears, the high-concentration sulfuric acid electrolyte has great resistance, and the solubility of lead sulfate is low is due to the layering of the negative electrode active material in the lower part. 7. Invite Aesi. However, according to the present invention, since the resistance within the electrode plate is low, sufficient current flows even in the lower part of the negative electrode plate even though it is far from the ear, resulting in a shortened battery life due to the lower part. Can solve problems.

This is clear from Example 2.

While the conventional sealed lead-acid battery Y has a short life due to the lower part of the negative electrode plate, the sealed lead-acid battery 2x according to the present invention and the high specific gravity electrolyte have a short life of 1.350d H2.
Battery 3x using SO4 showed extremely good lifetime performance.

A high-density electrolyte is an electrolyte that contains less H2O that does not participate in charge/discharge reactions, and is either a closed type or
Regardless of whether or not this is the case, it is possible to significantly improve the weight efficiency and volumetric efficiency of the battery. In conventional lead-acid batteries, the resistance of the negative electrode plate to high-density electrolytes was poor, so the use of high-density electrolytes meant that the batteries had a short lifespan.

However, according to the present invention, it is possible to make a lead-acid battery with high weight and volume efficiency without sacrificing the life span. This is clear from Example 2.

The unformed active material is lead sulfate (tribasic or tetrabasic) or lead oxide (when filled with cladding), which has no electronic conductivity.

Therefore, when the particles are chemically formed, the chemical formation proceeds in the order starting from the particles that are in contact with the lattice or core metal that is the current collector. Therefore, distant active material particles that are not in contact with the current collector will not undergo chemical conversion until they are supplied with electrons via the particles that exist between them and the current collector. Conventionally, positive electrode plates, in particular, had to be formed over a long period of time and with a large amount of electricity.
It required ~4 times as much. However, according to the present invention,
Even particles that are far away from the current collector are bonded to the current collector by electronically conductive whiskers, so that they are converted into active material particles as soon as chemical formation begins. Therefore, the efficiency of chemical conversion is extremely high, and even in the case of clad batteries, there is no need to mix red lead, etc., and the amount of electricity required for chemical conversion is within twice the theoretically required amount, and depending on the conditions, it can be up to 1. .1 times is sufficient. Furthermore, the formation time and amount of electricity can be reduced to A-% of the conventional amount, resulting in a highly productive and extremely inexpensive sealed lead-acid battery. This is clear from Example 3.

Conventionally, carbon black has been added to improve the charge acceptance of the negative electrode plate. This has the effect of increasing the charging capacity by lowering the hydrogen overvoltage of the negative electrode and increasing the current flowing at the end of charging. However, in practical use, this means that the amount of electricity that is overcharged is large. This is not at all preferable because it causes a decrease in water in the electrolytic solution due to electrolysis, an increase in the frequency of water replenishment, and acceleration of corrosion of the positive electrode grid.

This is because the electron conduction between the current collector and the active material particles that are far from the current collector depends only on the reduced active material particles and carbon black particles that exist between them. are doing.

According to the present invention, since the active material particles separated from the current collector also start being charged at the same time as charging starts, charging efficiency is very high.

Moreover, the characteristic feature is that carbon whiskers and Gra7ite whiskers are produced by hydrogen permeation of the negative electrode as shown in Example 4.
The key is not to lower LlE. It overcomes the drawbacks of conventional carbon black-added products, such as increased water replenishment frequency and accelerated corrosion of the positive electrode grid. The fact that the negative electrode has good charge acceptance is the same as the fact that it has high resistance to the above-mentioned metal 7 ace.

Therefore, it is clear that the sealed lead-acid battery of the present invention will have a longer life than the conventional one even when used as a float. This can be easily understood from Examples 2 and 4.

As described above, the whiskers used in the present invention are used to facilitate the flow of electrons to active material particles that are distant from the current collector. Therefore, it is preferable that the whiskers themselves have high electronic conductivity, are long in size, and have a large number of whiskers. The electron conductivity of the whiskers is preferably 1×10 −3 Ω°1 or more. What is more important is to electronically conductively connect as many active material particles as possible without drastically reducing the amount of active material. For this purpose, it must be in the form of short fibers with the smallest possible diameter and long length. Considering the above-mentioned active material particles present per unit volume, those having a diameter of 50 pm or more cannot be used because their number is small in relation to the volume they occupy. The diameter is 10! m or less, preferably less than 1 μm, and the aspect ratio must be 50 or more. Most preferably, the diameter is 0.01-1.
It is a whisker having an aspect ratio of 100 to 1000 in opm.

As for the material of the whisker, in addition to the carbon and graphite shown in the above embodiments, whiskers having electron conductivity that are not harmful to lead-acid batteries can also be used.

When whiskers are used as a positive electrode, not only carbon but also graphite, which has excellent oxidation resistance obtained by treating carbon at high temperatures, may be oxidized or physically removed from the active material by the generated oxygen gas. Nearly half of it is lost during the chemical conversion process. Therefore, when a lead-acid battery according to the present invention is assembled with a chemically formed electrode plate, the amount of whiskers remaining in the positive electrode plate is less than the amount originally mixed with the active material. If the effect of whiskers is to be expected not only during the chemical conversion process but also afterward, the ratio of whiskers to the active material must be initially increased. If only the effect during the chemical conversion process is expected, the amount may be less.

In the former, the ratio of Zhu Kasei to the positive electrode active material is 1 to 10
wt%, more preferably 1-5 wt%,
In the latter, 0.01-3vt%, more preferably 0.0
1-2. It should be Owt%.

In the case of a negative electrode, no carbon or graphite whiskers are lost. Its effect is maintained throughout the life of the battery, and it is easier to chemically form than the positive electrode. Therefore, the amount of whiskers should be determined based on the desired effect and economy, and this is a matter within the scope of design.

The amount of carbon whiskers and graphite whiskers relative to the negative electrode active material is 0.01 to 5 wt%, more preferably 0.01 to 2.0 wt%.

Another important point to maximize the effect of the whiskers is to bring the whiskers into contact with the active material particles.
- to ensure uniform dispersion. For this reason, as shown in Example 1, it is preferable to use the lead powder after dispersing it in water using an ultra-high-speed mixer instead of directly adding it to the raw material.

In order to improve the dispersibility in water, carbon or graphite whiskers may be treated with a surfactant or hydrophilic groups may be added directly to their surfaces in the gas phase.

In this way, uniform dispersion can be obtained without using an ultra-high speed mixer.

Another issue that must be considered when using whiskers is getting the active material density right. When using antimony-free pure lead, calcium alloys, or other antimony-free lead alloys as the positive electrode grid, if the apparent density of the active material is small, the electrolyte will diffuse too well; Before the active material is completely discharged, the corroded layer on the surface of the lattice is discharged and becomes lead sulfate, an insulator. This breaks the electrical connection between the active material and the lattice, making it impossible to extract the capacitance.

In order to prevent this, for example, when using carbon whiskers, if you use a paste prepared by adding and kneading an alkali metal salt of metaphosphoric acid or birophosphoric acid, such as sodium metaphosphate or sodium birophosphate, the ratio of whiskers to the active material This is advantageous because a high-density active material can be obtained even if there is a large amount of . Such an alkali metal salt of phosphoric acid changes the form of the corroded layer on the surface of the lattice, and the corroded layer does not insulate the lattice and the active material, so that the discharge can be maintained. Furthermore, it is more convenient.

The amount of negative electrode active material greatly influences high rate discharge capacity. Even when non-metallic whiskers are used for the negative electrode, if the alkali gold 114#A of birophosphoric acid or metaphosphoric acid is kneaded into the paste to increase its density, lead with better high rate discharge characteristics can be used. A storage battery is obtained.

The appropriate combination of these alkali metal salts of birophosphoric acid or metaphosphoric acid with the active material varies depending on the amount of sulfur and water used to prepare the base. However, the appropriate positive electrode paste density of a normal paste type electrode plate is 3.7 to 4.5'/
, 4. When trying to obtain a negative electrode paste density of 6.5 to 4,5 F/, i, the ratio is 0.00 to the active material.
It must be between 1 and 5 wt%. In this way, the apparent density of the positive electrode active material is 5.5 to 4.09/4, and the apparent density of the negative electrode active material is 5.1 to 4.0, which can fully satisfy both life performance and high rate discharge performance. 0sj is obtained.

This is because if it is less than 0.0O1vt%, the apparent density of the paste cannot be increased, and if it is more than 5wt%, the self-discharge rate of the resulting battery becomes too high, which is undesirable. When carbon fiber is mixed into an active material, there is a problem in that the apparent density of the active material decreases and its lifespan is shortened, as described above.

However, this will not happen if the whiskers of the present invention are used. In fact, the apparent density without additives is 4.0
When approximately 1% of carbon fiber was added to the positive electrode active material, the apparent density of carbon fiber decreased to 2.6, while that of whiskers only decreased to 3.73. .

Moreover, in this case, the number of carbon fibers present per 11 apparent volumes of the active material is approximately 2×10′, and the total surface area is approximately 80 cm.
d, whereas in the case of carbon whiskers, it is about lX10'', which is about 4900d, which is an order of magnitude larger.
It is better to have more than just books. Therefore, when carbon fibers with a large diameter are used, not only the contact pressure of the active material but also the area and number of fibers that can be contacted are extremely small compared to the case of whiskers.

Therefore, carbon maie";s with a diameter of 7 to 20 μm
- It has been found that when used, in order to maximize the effect, the density of the active material must be increased in order to bring as many active material particles into strong contact with the carbon fibers as possible.

In order to make carbon fiber exist while maintaining a high active material density, the above-mentioned alkali gold J of metaphosphoric acid [and/or
Alternatively, the addition of an alkali metal salt of bicarbonate is extremely effective, and unless it is used, the effect of incorporating carbon fiber cannot be fully exerted. When carbon fibers are mixed in, unless the carbon fiber is mixed with a carbon fiber of 4.8%, problems such as negative electrode discharge and discharge of the positive electrode lattice corrosion layer will occur, resulting in a shortened lifespan.

However, in order to achieve this while ensuring adhesion to the grid, it is necessary to coexist the alkali metal salt of metaphosphoric acid and/or the alkali metal salt of birophosphoric acid in an amount of 0.001 to 5 vt%.

Needless to say, this also applies when the whisker diameter is as large as about 7 to 10 pm.

In other words, even in the case of whiskers, the amount is 1 wt%.
To this extent, a sufficiently high active material density can be obtained even without the presence of an alkali metal salt of metaphosphoric acid and/or an alkali gold m salt of birophosphoric acid. However, when the amount is increased further, or in the case of whiskers having a diameter of 5 to 10 pm exceeding 1 μm, it is essential to coexist with an alkali metal salt of metaphosphoric acid and/or an alkali metal salt of birophosphoric acid. . From the point of view of such contact density, the whisker has a density of 2 or more, more preferably 1
Preferably, it has a specific surface area of 0 to 40-/9.

Lead-acid batteries can be roughly divided into three types depending on the shape of the current collector and the method of bringing the active material and the current collector into close contact.

@1 is a paste-type electrode plate in which a lattice-shaped pure lead or lead alloy obtained by methods such as casting, expanding, and braiding is filled with an active material paste.

The second method is to insert a tube made of fibers such as glass fiber or merry ester fiber into a cylindrical shape through a rod-shaped core metal made of pure lead or lead alloy shown in Example 3, and then create a cladding in which the tube is filled with an active material. It is a type plate.

The third type is a Tudor type electrode plate in which a current collector and an active material are obtained by electrolyzing a pure lead plate. The Kraft type electrode plate is used exclusively as a positive electrode, and the negative electrode plate serving as the counter electrode is usually a paste type electrode plate.

The present invention is not limited to the types of electrode plates, and can be applied to paste-type positive electrode plates, negative electrode plates, and clad-type electrode plates, excluding Tudor-type electrode plates, and has been found to be effective.

Also, lead-acid batteries usually require 105% to be fully charged.
You have to charge it to about 120%. Due to this overcharging, the water in the electrolyte is electrolyzed and the electrolyte is lost, so water must be periodically replenished. In order to reduce or eliminate this water refilling work, the alloy of the current collector may be made of a calcium-based alloy that does not contain antimony, or the amount of electrolyte may be reduced and absorbed and retained in a microporous material. ing. In addition, it is gelled with silicon dioxide and superabsorbent polymer hemorrhoids, and is sealed by combining oxygen gas generated at the positive electrode with the negative electrode active material at the end of charging. The present invention can be applied to any of these sealed lead acid batteries.

Effects of the Invention As described above, the sealed lead-acid battery of the present invention can improve the utilization rate of the positive and negative active materials, and has higher weight efficiency and volumetric efficiency than conventional active materials. Improved charging acceptability (charging efficiency) of 711! -) Improved resistance to sulfuric acid of the negative electrode active material, allowing use of higher concentration sulfuric acid electrolyte, greatly improving utilization without sacrificing lifespan. Since the amount of electricity required for forming the positive electrode plate can be greatly reduced and it can be made inexpensive, its industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1 is an electron micrograph showing carbon whiskers used in the sealed lead-acid battery of the present invention, and Figure 2 compares the relationship between capacity and discharge current between the sealed lead-acid battery of the present invention and a conventional product. Figure 5 is a diagram in which the capacity in Figure 2 is converted into active material utilization rate, Figure 4 is a diagram comparing the life performance of the sealed lead-acid battery according to the present invention and a conventional product, and Figure 5 is Figure 6 is a diagram comparing the ease of chemical formation between a sealed lead-acid battery according to the present invention and a conventional product. Figure 6 is a diagram comparing the relationship between the charge front flow and battery voltage between the sealed lead-acid battery according to the present invention and a conventional product. It is. X52X13X...Sealed lead acid battery 11 according to the present invention; Battery Y1 z...Conventional sealed lead acid battery tHII! Man
Yuroiwaike Co., Ltd. 1 shame xs'octop 1 no 1 Shiku

Claims (4)

[Claims] (1) The positive electrode plate consists of a current collector containing pure lead or a lead alloy, and the positive electrode active material whose main component is lead dioxide in close contact with the current collector, and the negative electrode plate consists of a current collector containing pure lead or a lead alloy, and a positive electrode active material whose main component is lead dioxide, and the negative electrode plate is made of pure lead, a Pb-Ca-based lead alloy, or other antimony. The electrolyte is absorbed and fixed by a porous separator made of fine glass fibers or ultrafine organic fibers. or fixed in gel form with a gelling agent made of silica, organic polymer, etc., and at least one of the positive and negative active materials has a diameter of 10 μm or less, an aspect ratio of 50 or more, and a specific surface area of m^/g or more. 1. A sealed lead-acid battery characterized in that carbon whiskers or graphite whiskers having an electron conductivity of 0.01 to 10 wt% relative to the active material are mixed. (2) Carbon whiskers or graphite whiskers are mixed in the negative electrode active material, these whiskers are mixed in the positive electrode active material as necessary, and the hydrogen overvoltage of the negative electrode plate does not contain antimony. The sealed lead-acid battery according to claim 1, which is substantially the same as or more noble than a negative electrode plate using a lead alloy. (3) The sealed lead acid battery according to claim 2, wherein the number of carbon whiskers or graphite whiskers is 1×10^9 or more per 1 cm^3 of apparent volume of the active material. (4) The electronic conductivity of the whisker is 1×10^-^3Ω・
3. The sealed lead-acid battery according to claim 3, wherein the battery is higher than cm.