JP2002313305A - Lead storage battery separator and lead storage battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for use in a lead acid battery high in mechanical strength, excellent in assembling workability and free to thin it, long in battery longevity as excellent in a hydrophilic property and liquid retentivity, excellent in a restraining effect of dendrite growth and capable of easily working on a bag type separator by thermal fusion, mechanical sealing, etc. SOLUTION: This separator for use in the lead acid battery is constituted of glass fiber and organic fiber with inorganic oxide coated on its surface. The lead acid battery uses this separator for use in the lead acid battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-acid battery separator composed of glass fibers and organic fibers, and a lead-acid battery composed of the lead-acid battery separator. The present invention relates to a lead-acid battery separator using organic fibers and a lead-acid battery capable of improving high-rate characteristics, extending the life, and increasing the capacity by using the lead-acid battery separator.

[0002]

2. Description of the Related Art Conventionally, as a separator for a sealed lead-acid battery, a sheet-like separator mainly composed of glass fiber has been used (Japanese Patent Laid-Open No. 4-106869).

[0003] In recent years, with the increase in output of lead storage batteries, thin separators have been demanded in order to improve high rate characteristics. However, mechanical strength such as tensile strength and penetration strength is low in a separator composed mainly of glass fiber, and in a thin glass fiber separator, the separator is torn by the load during battery assembly, There is a possibility that an object or the like penetrates through the separator and the positive electrode plate and the negative electrode plate are electrically short-circuited (short-circuited).

Hitherto, a method has been proposed in which organic fibers are mixed with glass fibers to increase the strength (Japanese Patent Application Laid-Open Nos. 54-22531, 56-99968, and 58-663). However, since the surface of the organic fiber is water repellent, the wettability to the electrolytic solution (sulfuric acid aqueous solution) is deteriorated, and the liquid absorbing property and liquid retaining property of the separator are reduced.

[0005] On the other hand, there has been proposed a method of increasing the affinity for an electrolytic solution by filling an inorganic oxide powder such as silica into the inside of a separator. Has to be reduced, and it is difficult to sufficiently increase the strength of the separator. The organic fiber itself is not directly hydrophilized, the water repellency of the fiber surface remains, and the electrolyte cannot be held on the surface of the organic fiber. Can not. Since the inorganic oxide powder is used together with the aggregating agent, the inorganic oxide powder agglomerates inside the separator, and the volume of space in which the electrolyte is to be held is reduced. Alternatively, since the aggregation of the inorganic oxide powder is uneven, the distribution of the space for holding the electrolyte is biased, and the charge / discharge efficiency is reduced.

[0006] A separator for a sealed type lead battery using fine glass fibers, acid-resistant organic fibers and silica powder, and fixing the silica powder with a resin binder (Japanese Patent Laid-Open No. 8-1300)
No. 01) has been proposed, but in this separator, there is a high possibility that the binder is eluted into the electrolyte and adversely affects the battery reaction.

[0007] When the battery is applied to a vibration source such as an automobile, there is a problem that the active material of the electrode plate falls off due to vibration, or the electrode plate moves and the positive electrode and the negative electrode come into contact. These problems can be solved by forming the separator into a bag shape and covering the electrodes.However, in the case of a separator composed of only glass fibers or a separator containing organic fibers with a small content, thermal fusion is not possible. However, there is a drawback that it is impossible to attach (heat seal) and mechanical sealing cannot be performed due to low strength, and it is difficult to process such a bag-shaped separator.

[0008] In general, in a separator of a lead storage battery,
When charge and discharge are continuously performed, metal lead derived from the electrode plate grows crystal inside the separator by the following reaction, and reaches the other electrode plate to cause a short circuit (short circuit). . That is, when the sulfate ions in the electrolytic solution are consumed at the end of discharge and the electrolytic solution becomes close to pure water, the solubility of lead ions increases and lead sulfate generated in the positive electrode and the negative electrode partially dissolves.
When charging is performed thereafter, lead ions in the electrolytic solution are reduced at the negative electrode, and metallic lead is deposited. This grows inside the separator to form needle-like crystals. The needle-like crystals of metallic lead are generally called "dendrites", but when the dendrites grow, they reach the other electrode plate and short-circuit (short-circuit), so that subsequent charging and discharging cannot be performed.

As a separator of an alkaline secondary battery different from a separator for a lead storage battery, a nonwoven fabric of an organic fiber whose surface is coated with fine particles of titanium oxide or zirconium oxide (Japanese Patent Laid-Open No. 11-315472) has been proposed. . However, the alkaline secondary battery uses a high-concentration alkaline electrolyte, and the sulfuric acid aqueous solution targeted by the present invention is used as an electrolyte. different.

[0010]

SUMMARY OF THE INVENTION The present invention is a separator for a lead-acid battery having high mechanical strength, excellent assembling workability, and capable of being thinned. It is long and excellent in suppressing the growth of dendrite, and can be easily processed into a bag-shaped separator by heat sealing or mechanical sealing. It is an object of the present invention to provide a lead storage battery capable of improving characteristics, extending the life, and increasing the capacity.

[0011]

The lead-acid battery separator of the present invention is a lead-acid battery separator composed of glass fiber and organic fiber, wherein the organic fiber is an organic fiber having a surface coated with an inorganic oxide. It is characterized by the following.

Since inorganic oxide-coated organic fibers are excellent in hydrophilicity, lead storage batteries having high mechanical strength and excellent hydrophilicity and liquid retention properties are obtained by using inorganic oxide-coated organic fibers in combination with glass fibers. Can be used as a separator.

In the present invention, since the organic fibers have a high hydrophilicity on the surface, the mechanical strength can be improved by using a relatively large amount of organic fibers. The problem of the short circuit due to the penetrating contact is eliminated, and the battery can be assembled with good workability even with a thin separator.

Further, by using a relatively large amount of organic fibers and, for example, arranging the organic fibers outside the separator, processing into a bag-like separator by heat fusion or mechanical sealing can be easily performed. .

Further, by filling the separator with the inorganic oxide, dendrite growth is suppressed and short-circuit resistance is improved.

In the present invention, the content ratio of the inorganic oxide-coated organic fibers in the separator for a lead storage battery is preferably 1 to 95% by weight.

Further, as the glass fiber, the average fiber diameter is 2 μm.
m or less, and the average fiber diameter of the organic fibers is preferably 0.2 to 30 μm.

As the inorganic oxide to be coated on the organic fiber, titanium dioxide, aluminum oxide, magnesium oxide, silica, calcium oxide, zirconium oxide, tin oxide, nickel oxide, cobalt oxide, vanadium oxide,
One or more members selected from the group consisting of yttrium oxide, ytterbium oxide, zinc oxide, potassium titanate and manganese oxide, preferably silica.

The organic fiber preferably has a porous layer formed on the surface thereof by aggregation of inorganic oxide fine particles. In this case, the particle size of the inorganic oxide fine particles is 1 to 10
Preferably, the thickness of the porous layer is 10 nm or more and 1/4 or less of the fiber diameter of the organic fibers.

The organic fibers used in the present invention include one or more selected from the group consisting of polyolefin fibers, polyester fibers, polyamide fibers and natural pulp fibers. High polyolefin fibers, especially polypropylene or polyethylene fibers, are preferred.

In the inorganic oxide-coated organic fiber, the weight ratio of the inorganic oxide to the total weight of the inorganic oxide and the organic fiber is preferably 3 to 30% by weight.

The separator for a lead-acid battery according to the present invention is a separator formed by mixing glass fibers and inorganic oxide-coated organic fibers, or laminating a glass fiber mat and a nonwoven fabric of inorganic oxide-coated organic fibers. Separator.

The lead storage battery of the present invention is constituted by using such a separator for a lead storage battery of the present invention.
It is possible to improve the high-rate characteristics by reducing the thickness of the separator, and to extend the service life and increase the capacity.

[0024]

Embodiments of the present invention will be described below in detail.

The glass fiber used in the present invention is a fine glass fiber having an average fiber diameter of 2 μm or less, for example, an average fiber diameter of 0.1 μm.
Fine glass fibers of 6 to 1 μm are preferred. When the average fiber diameter of the glass fiber exceeds 2 μm, the liquid holding power, the papermaking property, and the like decrease.

Since the fine glass fibers come into contact with the sulfuric acid in the electrolyte of the lead-acid battery, acid-resistant glass fibers, particularly alkali-containing glass fibers having good acid resistance, are preferred.

As the glass fibers, two or more glass fibers having different compositions and different fiber diameters may be used in combination.

On the other hand, as the organic fibers, polyolefin fibers, polyester fibers, polyamide fibers, natural pulp fibers, and the like can be used. Among them, an aqueous solution of sulfuric acid (specific gravity = about 1.3) of the electrolytic solution is used. Polyolefin fibers excellent in acid resistance, particularly polypropylene or polyethylene fibers, are preferred. As the organic fiber, one of these may be used alone, or two or more thereof may be used in combination.

Although the fiber diameter of the organic fiber is not particularly limited,
The average fiber diameter is preferably 0.2 to 30 μm. When the average fiber diameter of the organic fibers is smaller than 0.2 μm, the density of the obtained separator is too high, and the space for the electrolyte is small. The average fiber diameter of the organic fibers is 30.
When the thickness is larger than μm, the specific surface area of the obtained separator is small, and the liquid retaining property of the electrolyte is deteriorated.

The organic fibers may be used in a fibrous state, or may be used as a sheet such as a nonwoven fabric or a woven fabric.

As the inorganic oxide to be coated on the organic fibers, titanium dioxide, aluminum oxide, magnesium oxide, silica, calcium oxide, zirconium oxide, tin oxide, nickel oxide, cobalt oxide, vanadium oxide,
One or more of yttrium oxide, ytterbium oxide, zinc oxide, potassium titanate, manganese oxide, and the like can be used. Among them, those having high acid resistance are preferable, and silica is particularly preferable.

That is, when the inorganic oxide is dissolved in the electrolytic solution (aqueous sulfuric acid solution), the effect of improving the hydrophilicity is reduced. Therefore, an inorganic oxide having excellent acid resistance is preferable. However, even if the inorganic oxide dissolves, a slight amount of the inorganic oxide does not pose a problem since it does not affect the electrolytic solution if the amount is small.

In the present invention, the reason why silica is preferred as the inorganic oxide to be coated on the organic fibers is as follows. That is, the silica is dissolved in a small amount in the electrolytic solution (sulfuric acid aqueous solution) to slightly increase the viscosity of the electrolytic solution. This increase in viscosity suppresses stratification of the electrolyte (a phenomenon in which the specific gravity of the electrolyte differs between the upper part and the lower part of the battery). This suppression effect works particularly effectively at high temperatures (50 ° C. or higher) and contributes to prolonging the life of the battery.

It is preferable that such an inorganic oxide forms a porous layer on the surface of an organic fiber by aggregation of fine particles of the inorganic oxide. With such a porous layer, an electrolytic solution can be taken into the voids of the porous layer to obtain good liquid retention. In this case, the fine particles of the inorganic oxide have a particle size of 1 to 100 nm, particularly 5 to 50 nm, the thickness of the formed porous layer is 10 nm or more, particularly 20 nm or more, and 1/4 or less of the fiber diameter of the organic fiber, particularly It is preferably 1/6 or less. Fine particles having a particle size of less than 1 nm are difficult to produce, and those having a particle size of more than 100 nm tend to peel off from the surface of the organic fiber, and the formed porous layer also has poor homogeneity. If the thickness of the porous layer is less than 10 nm, the amount of electrolyte that can be taken into the porous layer is small, and if the thickness is more than 1/4 of the fiber diameter of the organic fiber, the porous layer is easily peeled.

The organic fiber on which the porous layer made of the fine particles of the inorganic oxide is formed is immersed in the dispersion of the fine particles of the inorganic oxide, and the dispersion is converted into the organic fiber. It can be easily manufactured by attaching and then drying. Thereby, the inorganic oxide fine particles can be firmly adhered to the surface of the organic fiber without using a binder, and a porous layer of the inorganic oxide can be formed. Here, examples of the dispersion medium for preparing the dispersion liquid of the fine particles of the inorganic oxide include water and / or an organic solvent, particularly alcohol such as ethanol and 2-propanol, or a mixture of these alcohols and water. Liquids are preferred.

When the organic fibers are used in the form of a sheet such as a nonwoven fabric or a woven fabric, the treatment for forming the porous layer of the inorganic oxide fine particles on the organic fibers in this manner is performed after the organic fibers are formed into a sheet in advance. Alternatively, after forming the porous layer in a fibrous state, this may be formed into a nonwoven fabric or a woven fabric.

The amount of the inorganic oxide adhered to the organic fiber depends on the specific gravity of the organic fiber and the inorganic oxide, and cannot be specified unconditionally. However, the amount is such that the surface of the organic fiber can be uniformly coated. Any amount is acceptable. If the amount of the inorganic oxide adhered is too small, the water repellency of the organic fiber appears, and the effect of improving the liquid retaining property and liquid absorbing property of the electrolytic solution cannot be obtained because the hydrophilicity is insufficient. If the amount of the inorganic oxide attached is large, for example, after the organic fiber is formed into a sheet, when the inorganic oxide is attached by the above-described method, the voids of the organic fiber sheet are filled with the inorganic oxide and the electrolyte In this case, the voids in which the liquid enters are lost, so that the liquid retaining property is undesirably lowered. However, such a problem does not occur when the organic fibers to which the inorganic oxide has been attached in advance are in the form of a sheet. Therefore, when the amount of the inorganic oxide to be attached is increased, the inorganic oxide is attached in advance. It is preferable to form the organic fibers into a sheet.

For example, when polypropylene fibers are used as the organic fibers and silica is used as the inorganic oxide,
The silica is preferably attached so as to be 3 to 30% by weight based on the total weight of the polypropylene fiber and the silica.

In the present invention, the content ratio of the inorganic oxide-coated organic fibers in the separator is preferably from 1 to 95% by weight. When the amount of the inorganic oxide-coated organic fibers is less than this range, the effect of improving the mechanical strength due to the blending of the organic fibers cannot be sufficiently obtained, and when the amount is larger than this range, the content of the glass fibers is relatively large. Since the ratio is reduced, excellent hydrophilicity and liquid retention due to glass fibers cannot be obtained. That is, although the inorganic oxide-coated organic fiber has improved hydrophilicity by being coated with an inorganic oxide, its hydrophilicity is sufficient compared to glass fibers, particularly fine glass fibers having an average fiber diameter of 2 μm or less. It cannot be said that there is, therefore, in the present invention, it is preferable to use glass fibers in an essential amount, and to ensure hydrophilicity and liquid retaining property, in order to ensure hydrophilicity and liquid retention.

[0040] Such an inorganic oxide-coated organic fiber,
The lead-acid battery separator of the present invention composed of glass fibers may be formed of a mixed layer of organic fibers and glass fibers, or may be a laminate of an organic fiber layer and a glass fiber layer. For example, it is manufactured as follows. By mixing the glass fiber and the inorganic oxide-coated organic fiber and forming the paper according to a conventional method, a separator comprising a mixed mat of the glass fiber and the organic fiber is obtained. This separator preferably has a thickness of 0.1 to 1.5 mm. A two-layer separator is obtained by laminating a glass fiber mat obtained by papermaking according to a conventional method using glass fibers and a nonwoven fabric obtained by papermaking according to a conventional method using inorganic oxide-coated organic fibers. . Here, the glass fiber mat has a thickness of 0.1 to 1.5 mm and a density of 0.1 mm.
~0.25g / cm ^3, it is preferable nonwoven inorganic oxide coating organic fibers has a thickness 0.05-0.4 mm. Further, in this case, the glass fiber mat and the nonwoven fabric of the organic fiber may be simply overlapped, may be bonded with an adhesive, or may be mechanically bonded with a press roll or the like. There is no particular limitation on the number of layers of the glass fiber mat and the nonwoven fabric of the organic fiber. Further, a laminate of a glass fiber mat and the above-described mixed mat may be used, or a stack of an organic fiber nonwoven fabric and the above-mentioned mixed mat may be used.

In the case where the separator is subjected to processing for filling the electrode by a heat fusion method or a mechanical method, a layer of the inorganic oxide-coated organic fiber or a large amount of the inorganic oxide-coated organic fiber is contained by the above method. Layer and a layer of glass fiber or a layer containing a large amount of glass fiber, and preferably a processed surface is a layer of an inorganic oxide-coated organic fiber or a layer containing a large amount of an inorganic oxide-coated organic fiber. .

The lead-acid battery separator of the present invention comprises:
By blending the inorganic oxide-coated organic fiber with the glass fiber, the mechanical strength is improved and the hydrophilic property is ensured, and other than the glass fiber and the inorganic oxide-coated organic fiber as long as the object of the present invention is not impaired. May be contained.

The sealed lead-acid battery of the present invention is manufactured by using such a separator of the present invention according to a conventional method.

[0044]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

The methods for measuring the physical properties and characteristic values of the separators in the examples and comparative examples are as follows. Thickness (mm): The thickness T (SBA450) measured with the sample pressed in the thickness direction at a pressure of 19.6 kPa.
1) was determined. Density (g / cm ³ ): From the thickness T measured while pressing the sample at a pressure of 19.6 kPa, the sample weight W measured with an electronic balance, and the sample area S, “W / (T ×
S) ". Tensile strength (N / 10 mm ² ): Measured by SBA4501. Penetration strength (relative value): A needle having a spherical tip with a thickness of 1 mm was inserted in a direction perpendicular to the fixed sample by 12 mm.
It pressed at the speed of 0 mm / min, and measured the maximum load at the time of penetration. Since this measured value is affected by a minute difference in the shape of the needle tip, it was evaluated as a relative value to the measured value of the sample of Comparative Example 1 (the measured value of Comparative Example 1 is 100). Liquid absorption rate (mm / min): The sample was vertically set, and its lower part was immersed in dilute sulfuric acid having a specific gravity of 1.30, and the liquid level rising for 1 minute from the immersion was measured. Electrochemical short circuit time (relative value): placed between ^two flat lead electrode plates (area = approximately 7 mm ² ) with a 0.5 mm thick separator interposed therebetween, immersed in a saturated aqueous solution of lead sulfate, A constant voltage of 10 V is applied thereto while a compression force of .94 Pa is applied. When the metal lead (dendrites) grown from the negative electrode reaches the positive electrode, the resistance value between the electrodes sharply decreases, so this time was measured. This measured value was evaluated as a relative value to the measured value of the sample of Comparative Example 1 (the measured value of Comparative Example 1 is set to 100).

Example 1 A polyolefin-based fiber (polypropylene fiber having an average fiber diameter of 12 μm) was formed to a thickness of 0.13 mm by a papermaking method.
Was manufactured. After immersing this nonwoven fabric in an ethanol dispersion of silica fine particles (average particle size: 20 nm),
By drying at 0 ° C., a nonwoven fabric having a porous layer of fine silica particles formed on the fiber surface was produced. The attached amount of the silica fine particles was 10% by weight based on the total weight of the silica fine particles and the polyolefin fiber.

Separately, fine glass fibers (average fiber diameter: 1.
0 μm) only and the thickness is 0.20 mm and the density is 0.1
A glass fiber mat of 4 g / cm ³ was produced.

The silica-coated polyolefin-based nonwoven fabric and the glass fiber mat were overlapped to form a separator. The content ratio of the glass fiber and the silica-coated organic fiber of this separator is as shown in Table 1.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

Example 2 In Example 1, in producing a silica-coated polyolefin fiber nonwoven fabric, the silica concentration in the dispersion of silica fine particles was increased, and the amount of silica fine particles attached was reduced to the total weight of silica fine particles and polyolefin fibers. 30% by weight
A non-woven fabric of silica-coated polyolefin-based fiber was produced in the same manner except that the above-described method was used, and the resultant was similarly laminated with a glass fiber mat to obtain a separator. The content ratio of the glass fiber and the silica-coated organic fiber of this separator is as shown in Table 1.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

Comparative Example 1 A glass fiber mat having a thickness of 0.30 mm was manufactured in the same manner as in the method of manufacturing the glass fiber mat in Example 1.
A separator made of only glass fiber was used.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

Comparative Example 2 A nonwoven fabric of 0.13 mm thick polyolefin fiber was produced in the same manner as in Example 1 except that a polyolefin fiber not subjected to silica coating was used. The separator was a nonwoven fabric-based separator only.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

Comparative Example 3 A nonwoven fabric of a silica-coated polyolefin fiber was produced in the same manner as in the method of producing a nonwoven fabric of a silica-coated polyolefin fiber in Example 1, and a separator containing only the nonwoven fabric of the silica-coated polyolefin fiber was used.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

Comparative Example 4 A nonwoven fabric of a polyolefin fiber was produced in the same manner as in Comparative Example 2.
A separator was obtained by overlapping with a glass fiber mat manufactured in the same manner as described above. The content ratio of the glass fiber and the organic fiber in this separator is as shown in Table 1.

Various physical properties and characteristics of this separator were measured, and the results are shown in Table 1.

[0060]

[Table 1]

The following is clear from Table 1.

That is, a comparison between Examples 1 and 2 and Comparative Examples 1 and 4 reveals that the use of organic fibers significantly improves the tensile strength and the penetration strength. Also,
In Examples 1 and 2 using silica-coated organic fibers as the organic fibers, no remarkable decrease in hydrophilicity due to the use of the organic fibers was observed, but rather, the hydrophilicity was improved.

Further, by comparing Examples 1 and 2 and Comparative Examples 1 and 2, it can be seen that the short-circuit resistance of the separator is greatly improved by using the silica-coated organic fiber.

Further, by comparing Examples 1 and 2 and Comparative Example 3, it can be seen that even if silica-coated organic fibers are used, sufficient hydrophilicity cannot be obtained unless glass fibers are used. That is, the separator made of the fine glass fibers of Comparative Example 1 has a liquid absorption rate slightly lower than that of the separators of Examples 1 and 2, though its density is about half. From this, the fine glass fiber,
Considering the specific surface area, it can be said that the electrolyte solution retention property is higher than that of the silica-coated organic fiber. Therefore, in the separator using only the silica-coated organic fiber as in Comparative Example 3, sufficient characteristics in terms of hydrophilicity cannot be obtained.

[0065]

As described above in detail, according to the lead storage battery separator of the present invention and the lead storage battery using the same, the following excellent effects can be obtained. By combining inorganic oxide-coated organic fibers, mechanical strength can be improved without lowering hydrophilicity, and when the separator is thinned, breakage of the separator and contact of electrodes through the electrode are prevented, thereby assembling the battery. Workability is also improved. Therefore, it is possible to improve the high-rate characteristics of the lead storage battery by reducing the thickness of the separator. By filling the inside of the separator with the inorganic oxide,
The hydrophilicity and short circuit resistance are improved, and the capacity and life characteristics of the lead storage battery are improved. By blending the organic fiber, it is possible to easily cope with an electrode bag packing process by a heat fusion method or a mechanical method.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsushi Asada 4-7-28 Kitahama, Chuo-ku, Osaka-shi, Osaka F-term in Nippon Sheet Glass Co., Ltd. 5H021 BB12 CC02 EE04 EE22 EE28 HH01 HH03 5H028 AA05 EE05 EE06 EE08 EE08 EE10 HH01 HH05

Claims (14)

[Claims] 1. A lead storage battery separator comprising a glass fiber and an organic fiber, wherein the organic fiber is an organic fiber having a surface coated with an inorganic oxide. 2. The separator for a lead-acid battery according to claim 1, wherein the content ratio of the organic fibers coated with the inorganic oxide in the separator for a lead-acid battery is 1 to 95% by weight. 3. The separator according to claim 1, wherein the glass fibers are fine glass fibers having an average fiber diameter of 2 μm or less. 4. The separator for a lead-acid battery according to claim 1, wherein the organic fibers have an average fiber diameter of 0.2 to 30 μm. 5. The method according to claim 1, wherein the inorganic oxide is titanium dioxide, aluminum oxide, magnesium oxide, silica, calcium oxide, zirconium oxide, tin oxide, nickel oxide, cobalt oxide, or oxide. A separator for a lead-acid battery, wherein the separator is at least one member selected from the group consisting of vanadium, yttrium oxide, ytterbium oxide, zinc oxide, potassium titanate, and manganese oxide. 6. The separator for a lead storage battery according to claim 5, wherein the inorganic oxide is silica. 7. The separator for a lead-acid battery according to claim 1, wherein a porous layer is formed on the surface of the organic fiber by aggregation of the inorganic oxide fine particles. 8. The method according to claim 7, wherein said inorganic oxide fine particles have a particle size of 1 to 100 nm, and said porous layer has a thickness of 1 to 100 nm.
A separator for a lead storage battery, wherein the separator has a fiber diameter of 0 nm or more and 1/4 or less of the fiber diameter of the organic fiber. 9. The organic fiber according to claim 1, wherein the organic fiber is at least one selected from the group consisting of polyolefin fibers, polyester fibers, polyamide fibers and natural pulp fibers. A lead-acid battery separator characterized by the above-mentioned. 10. The separator for a lead storage battery according to claim 9, wherein the organic fiber is a polypropylene or polyethylene fiber which is a polyolefin fiber. 11. The separator for a lead-acid battery according to claim 1, wherein the weight ratio of the inorganic oxide to the organic fiber coated with the inorganic oxide is 3 to 30% by weight. . 12. The separator for a lead storage battery according to claim 1, wherein the glass fiber and the organic fiber coated with the inorganic oxide are mixed and paper-made. 13. The lead-acid battery according to claim 1, wherein a mat made of the glass fiber and a non-woven fabric of an organic fiber coated with the inorganic oxide are laminated. Separator. 14. A lead-acid battery comprising the lead-acid battery separator according to any one of claims 1 to 13.