JPH02284351A - Separators for lead-acid batteries and lead-acid batteries - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a separator for a lead-acid gas pond and to extending the life of a lead-acid battery using this separator.

Conventional technology Lead-acid batteries are widely used as secondary batteries that have a good balance between cost and performance.

Currently, the types of lead-acid batteries used in boat fishing are roughly divided into two types based on the type of positive electrode plate: paste type and clad type.

For both of these methods, the cathode absorption type sealed type is becoming mainstream.

To make the electrolyte non-fluid for sealing, there are generally two methods: using a glass mat made from glass fiber paper, and using fine silica powder as a gelling agent, but currently glass mats are used. method is the mainstream.

Particularly in the paste type, characteristics such as the ability of the glass mat to maintain pressure against the liquid-absorbing electrode plate (hereinafter referred to as group pressure) affect the battery characteristics.

In other words, the glass mat currently used for aggregation exhibits a phenomenon in which the group pressure decreases when it absorbs an electrolyte compared to when it is dry.

Therefore, in order to obtain a predetermined group pressure during liquid absorption and to improve stable battery characteristics and battery characteristics, it is necessary to insert the electrode plate group into the battery case with a group pressure several times that value.

This was considered to be one of the causes of poor productivity.

Problems to be Solved by the Invention In lead-acid batteries that use a glass mat with a retainer as described above, the current glass mat has the disadvantage that when it absorbs electrolyte, the group pressure decreases significantly compared to when it is dry. ing.

Typical lead-acid batteries have a power rating of 1o~aokg/dn in dry conditions.
A group pressure of 1 is applied to a glass mat and used as a battery separator, but when an electrolyte is injected, the pressure decreases to about W~. Therefore, in order to apply a predetermined group pressure to the electrode plate surface after injecting the electrolyte, it is necessary to apply a group pressure of 30 kg/&A or more when inserting the electrode plate group and insert the electrode plate group into the battery case. Ta.

Therefore, before inserting the electrode plate group into the battery case, a work step such as applying pressurization to the electrode plate group is required in advance.

Also, the group pressure applied from this separator to both electrode plates is 10k.
When it is less than g/d%, there is a problem that the active material softens and falls off significantly as the number of cycles increases, resulting in rapid deterioration of the cycle life characteristics.

When using the separator according to the present invention, when inserting the electrode plate group into the battery, there is no need to particularly apply group pressure between the electrode plate group and the battery case, so the workability of the insertion work is improved, and the electrode plate group No excessive stress is applied to the group when inserted.

Therefore, manufacturing defects due to drop-off of the active material from the electrode plates are also reduced. Furthermore, since it is possible to apply an appropriate group pressure after injection, cycle life characteristics and overcharge characteristics can be significantly improved.

Means for Solving the Problems In the present invention, a separator is made of a nonwoven fabric made by making a paper that is a complete mixture of glass fibers and polymer fibers or particles, dried, and then heat-pressed at a temperature near the melting point of the polymer to form a porous sheet.
The idea is to apply appropriate pressure to the cathode and anode plates by expanding the separator itself after injecting the electrolyte.

Function: In the present invention, the polymer fibers or particles used for mixing with glass fibers have the property of causing volumetric expansion by being hydrolyzed or sulfonated by the sulfuric acid of the electrolytic solution. Therefore, the polymer is made into a fiber or particulate form, mixed with glass fiber, dried, and then heat pressed.
Polymers and parts of the polymer are continuously welded by heat welding, and when an electrolyte is injected into a nonwoven fabric processed into a porous sheet, the nonwoven fabric itself expands, applying an appropriate group pressure between the two electrode plates. be done.

By heat-pressing and welding part of the glass fiber and polymer, the expansion force becomes anisotropic, promoting expansion in the thickness direction, and suppressing expansion in the direction perpendicular to the thickness.

That is, by constructing a lead-acid battery using this separator, the characteristics of the lead-acid battery can be improved without reducing manufacturing productivity.

FIG. 1 shows an example of the change in group pressure that occurs due to the separator of the present invention absorbing electrolyte and expanding.

Figure 4 shows an example in which a common glass fiber non-woven fabric of Kogyo is used as a retainer, and Figure B is an example in which the separator of the present invention is used as a retainer.

Example An embodiment of the present invention will be described below.

Two sheets of 40cm x 30m thick 3.6mm anode plates, three 1.7mm thick ones of the same shape for cathode plates, and a separator made of a mixture of glass fiber and polymer compound fiber according to the present invention. I used the one I made. - For example, 30% of glass fibers have a fiber diameter of 0.7 μm to 3 μm and a length of 6WIII to 20111 m, and a fiber diameter of 0.1 μm to 2 μm is obtained by formalizing a portion of Pvm as a polymer compound.

Those with a length of 6 to 20 days were set at 70%. This n was made into 1 and 7 baskets of nonwoven fabric corresponding to the distance between the two electrode plates.

Considering the sulfuric acid content consumed in the process of hydrolysis or sulfonation as an electrolyte, the specific gravity is 1.300 (at20'
C) 1500ft was used. From the above, a battery with a 10 hour rate capacity of 2 μh and a rated voltage of 2 V was manufactured.

We compared the recycling life characteristics of all similar batteries using a manufacturing method that does not apply pressure when inserting the electrode plates into the battery case, using a conventional separator made only of glass fiber.

The charging conditions for the cycle life test were constant voltage constant current charging with an initial current of 0.8 μm and a charge control voltage of 2.46 V, and the discharging conditions were a resistance discharge equivalent to 0.2 μm, and a repeated test was performed in which the battery was discharged to 1.75 V. Ta. The end of the cycle life was determined at the time when the discharge duration reached 60% of the initial capacity.

Figure 2 shows the results of the cycle life test. It can be seen that in the battery according to the present invention in which the separator is fully bent, the appropriate pressure applied between the two electrode plates prevents the active material from softening and falling off, so that the cycle life characteristics are significantly improved.

Effects of the Invention In the separator used in the present invention, the polymer synthetic fiber portion undergoes hydrolysis or sulfonation by sulfuric acid in the electrolytic solution, thereby causing volume expansion. By applying appropriate pressure between the two electrode plates by utilizing this volumetric expansion, the effect of preventing the active material from softening and falling off can be achieved with almost no pressure being applied during battery manufacture.

This reduces the number of man-hours required during battery manufacturing and reduces defects due to stress.

[Brief explanation of drawings]

Figure 1 shows the changes in group pressure over time when an electrolytic solution (sulfuric acid aqueous solution) is injected when a current general non-woven glass fiber fabric is used as a retainer and when the separator of the present invention is used as a retainer. Figure. Figure 2 shows a conventional glass fiber non-woven fabric used as a retainer and a dry group pressure of 20 kg/dn! Using the separator in one embodiment of the present invention as a retainer, the group pressure during drying was set to 0.1 kg/dn.
1 is a diagram showing the cycle life characteristics of battery B designed in accordance with I.

Claims (2)

[Claims] (1) Paper is made by mixing glass fibers with polymer fibers or particles that have functional groups that can be hydrolyzed or sulfonated by the sulfuric acid in the electrolyte, and whose volume expands by the sulfuric acid. A separator for lead-acid batteries characterized by being molded into a porous sheet by heat pressing at high temperatures. (2) Making paper by mixing glass fibers with polymer fibers or particles that have a functional group that can be hydrolyzed or sulfonated by sulfuric acid in the electrolytic solution and that expands in volume by sulfuric acid;
After drying, heat press at a temperature near the melting point of the polymer.
A lead-acid battery characterized by using a porous sheet-shaped separator as a retainer.