JPH07161342A - Separator for lead-acid battery - Google Patents

Abstract

PURPOSE:To improve the electrolyte holding force of a mat-shape separator, and to prevent the contraction of battery life caused by separation of active materials out of the plate by containing aluminium phosphate in the separator and by constantly maintaining good resiliency of the separator. CONSTITUTION:Aluminium phosphate is contained as a binder in a matshape separator made of the nonwoven fabric of glass fiber by no less than 1wt.% and no more than 5wt.% to the weight of the glass fiber. The wettability of the aluminium phosphate to electrolyte and the electrolyte holding capacity of the aluminium phosphate are higher than acrylic resin, and since phosphate is not oxidized by oxygen gas generated from a positive electrode plate during battery charging, the resiliency of the separator can be maintained constantly in a good condition. Since a positive electrode active material is hardened by phosphate, softening or separation of the active material out of the positive electrode plate can be prevented. The charging/discharging cycle life characteristic of the battery can thus be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-acid storage battery, and more particularly to a mat-shaped separator made of fine glass fiber nonwoven fabric.

[0002]

2. Description of the Related Art Conventionally, a separator disposed between a positive electrode plate and a negative electrode plate in a sealed lead-acid battery is a mat-shaped separator made of fine glass fibers using acrylic resin as a binder. The mat-like separator made of this fine glass fiber holds the electrolytic solution therein and at the same time adheres to the positive and negative electrode plates by the elastic force of the separator itself to prevent the active material from falling off from the electrode plate.

[0003]

However, in the matte separator made of fine glass fibers containing an acrylic resin as a binder as described above, the acrylic resin itself has a low impregnating ability to hold the electrolytic solution, and the separator is sufficiently separated. The electrolyte could not be retained inside.

Further, the acrylic resin is easily oxidized by the oxygen gas generated from the positive electrode plate during charging, the binding effect of the acrylic resin is gradually reduced by the oxidation, and the elasticity of the separator is also reduced, so that the active material falls off from the electrode plate. Therefore, the life characteristics of the battery were deteriorated.

The present invention is intended to solve these problems, and enhances the electrolytic solution holding power of a mat-shaped separator made of a non-woven fabric of fine glass fibers, and at the same time, keeps the elasticity of the separator good from the electrode plate. The present invention provides a lead-acid battery separator that can prevent a decrease in battery life due to the removal of the active material.

[0006]

In order to solve the above-mentioned problems, the lead-acid battery separator of the present invention contains aluminum phosphate in a fine glass fiber nonwoven fabric, preferably with respect to the weight of the glass fiber. The content is 1 to 5% by weight.

[0007]

The mat-shaped separator made of the non-woven glass fiber of the present invention contains aluminum phosphate as a binder in an amount of 1 to 5% by weight based on the weight of the glass fiber.

This aluminum phosphate has higher wettability with respect to the electrolytic solution and retention of the electrolytic solution than the acrylic resin. Further, since the phosphate is not oxidized by the oxygen gas generated from the positive electrode plate when the battery is charged, the elasticity of the separator can always be kept good, and the phosphate acts to cure the positive electrode active material. Therefore, the active material can be prevented from softening or falling off from the positive electrode plate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

First, a fine glass fiber having an average fiber diameter of 0.8 μm and 3 as a binder, based on the weight of the glass fiber.
After weight percent aluminum phosphate was dispersed and mixed in an aqueous solution having a pH of about PH3 in a diffusion tank, this was paper-made using a paper machine to prepare a glass fiber mat-shaped separator of the present invention. A sealed lead acid battery having a nominal specification of 12V24Ah was produced using this separator, predetermined positive and negative electrode plates, and an electrolytic solution, and this was used as the battery of the present invention.

As a comparative example, acrylic resin fiber was used as a binder, and a mat-shaped separator made of a non-woven fabric of glass fiber produced in the same manner as the present invention was used to produce a sealed lead acid battery having a nominal specification of 12V24Ah. Then, this was used as a conventional battery.

A charge / discharge cycle life test was carried out using these batteries. The cycle life test was performed by constant voltage charging at a voltage of 14.7 V and discharging at a current of 0.25 CA to a voltage of 10.5 V.

The results are shown in FIG. As shown in FIG. 1, the battery of the present invention was able to have longer cycle life than the conventional battery.

When the state of the separator was examined by disassembling the battery according to the present invention and the conventional battery, the separator according to the present invention had a larger amount of electrolyte retained than the conventional separator, and the elasticity of the glass fiber mat itself was excellent. .

Further, in the battery of the present invention, it was possible to prevent the active material from falling off from the positive electrode plate. In the examples of the present invention, the weight of the aluminum phosphate as the binder was set to 3% with respect to the weight of the glass fiber, but if it is less than 1%, the amount of the binder is small and the binding force of the glass fiber is small. If it exceeds 5%, the amount of the binder will be too large, and the amount of the electrolytic solution held in the glass fiber mat will decrease. Therefore, the amount of aluminum phosphate is preferably 1% by weight or more and 5% by weight or less based on the weight of the glass fiber.

Further, although the aluminum phosphate dispersion is used in the present invention, the same effect can be obtained by using other phosphate solutions.

[0017]

As described above, the lead acid battery separator of the present invention contains 1 to 5% by weight of aluminum phosphate in the fine glass fiber non-woven fabric based on the weight of the glass fiber. A mat-shaped separator made of a non-woven fabric can be used to improve the electrolyte holding power and to improve the adhesion of the separator to the electrode plate to prevent the active material from falling off from the electrode plate, thus improving the charge / discharge cycle life characteristics of the battery. I was able to.

[Brief description of drawings]

FIG. 1 is a diagram showing charge / discharge cycle life characteristics of the present invention and a conventional battery.

Claims (2)

[Claims] 1. A lead storage battery separator comprising aluminum phosphate in a fine glass fiber non-woven fabric. 2. The lead acid battery separator according to claim 1, wherein the content of aluminum phosphate is 1 to 5% by weight based on the weight of the glass fiber.