JP2014078325A - Lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead storage battery capable of exhibiting a satisfactory output characteristic in charge/discharge cycle in which a low-rate discharge capacity has the maximum value while preventing internal short circuit.SOLUTION: The lead storage battery includes: at least one electrode plate group; electrolytic solution; battery case storing the electrode plate group and the electrolyte; a lid closing an opening of the battery case; and a control valve. The electrode plate group includes: a positive electrode plate; a negative electrode plate; and a separator for separating the positive electrode plate from the negative electrode plate. The separator further include a mat separator of glass fiber; and an unwoven fabric separator. The ratio A/B between the total pore volume A of the mat separator and the total pore volume B of the unwoven fabric separator is 5-10.

Description

  The present invention relates to a lead storage battery in which a mat separator made of glass fiber and a nonwoven fabric separator are used in combination.

  Lead storage batteries are widely used as power sources for power storage systems, electric devices, and electric vehicles. Unlike the case where the lead acid battery used for such an application is used for starting an automobile, the electrolyte is often reduced and absorbed in the positive electrode plate, the negative electrode plate and the separator separating them. The lead storage battery adopting this configuration uses a control valve that opens when the internal pressure of the battery reaches a predetermined value, instead of a liquid plug for opening and replenishing water when the electrolyte is reduced. It is called a type lead acid battery.

  In order to increase the capacity per unit volume of the lead storage battery, it is necessary to reduce the distance between the positive electrode plate and the negative electrode plate (between the electrodes) (that is, to reduce the separator when the battery is configured). When the distance between the electrodes is reduced, the active material expanded by repeating the charge / discharge cycle occupies the distance between the electrodes, so that an internal short circuit easily occurs.

  Therefore, as shown in Patent Document 1, a mat separator made of glass fiber and a nonwoven fabric separator are used together, or as shown in Patent Document 2, two kinds of nonwoven fabric separators are used together, while holding the electrolytic solution. This will prevent internal short circuit.

JP-A-10-040896 JP 2008-226697 A

  However, even when the lead storage batteries shown in these patent documents are randomly configured, the output characteristics after repeated charge / discharge cycles are not good. The present invention is for solving this problem, and an object thereof is to provide a lead-acid battery that exhibits good output characteristics in a charge / discharge cycle in which a low rate discharge capacity exhibits a maximum value while suppressing an internal short circuit. To do.

  In order to solve the above-described problem, the invention described in claim 1 includes at least one electrode plate group, an electrolytic solution, a battery case for storing these, a lid for sealing the opening of the battery case, and a control. And the electrode plate group includes a positive electrode plate, a negative electrode plate, and a separator separating the positive electrode plate, the separator further including a mat separator made of glass fiber and a non-woven fabric separator, and the total pores of the mat separator It is related with the lead acid battery characterized by ratio A / B of the volume A and the total pore volume B of a nonwoven fabric separator being 5-10.

  The invention according to claim 2 is characterized in that, in claim 1, the mat separator has a thickness of 0.8 mm or more and 1.4 mm or less.

  The invention described in claim 3 is characterized in that, in claim 1, a plurality of electrode plate groups are provided, and a connecting part for connecting the electrode plate groups is provided.

  By using the present invention, it is possible to provide a lead-acid battery that exhibits good output characteristics in a charge / discharge cycle in which a low rate discharge capacity exhibits a maximum value while suppressing an internal short circuit.

Schematic which shows the lead acid battery of Embodiment 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic view showing a lead-acid battery according to the first embodiment. The lead-acid battery includes a plurality of electrode plate groups 1, an electrolytic solution (not shown), a battery case 2 for storing them, a lid 3 for sealing the opening of the battery case 2, and a control valve (not shown). A connecting component 4 for connecting the electrode plate groups 1 to each other, and a positive polarity and a negative polarity terminal 5. The electrode plate group 1 includes a positive electrode plate 1a, a negative electrode plate 1b, and a mat separator 1c and a nonwoven fabric separator 1d made of glass fibers separating them.

  The first embodiment is characterized in that the ratio A / B between the total pore volume A of the mat separator 1c and the total pore volume B of the nonwoven fabric separator 1d is 5 or more and 10 or less.

  The details that led to the first embodiment will be described below, including the knowledge obtained by the present inventors.

  Patent Document 2 describes that the balance between the electrolytic solution holding force and the strength of the first mat separator made of a nonwoven fabric can be achieved by optimizing the tensile strength value that shows a negative correlation with the electrolytic solution holding force. Has been. Taking advantage of this knowledge, even if the second mat separator (nonwoven fabric) in Patent Document 2 is replaced with a mat separator 1c made of glass fiber, sufficient output characteristics can be obtained in a charge / discharge cycle in which the low rate discharge capacity is maximum. I knew that I couldn't get it.

  As for the balance of the holding power of the electrolytic solution when using two kinds of separators together, it is sufficient to consider only the strength of the nonwoven fabric separators as in Patent Document 2, but as a result of the intensive studies by the inventors, it is made of glass fibers. When combining different types of separators such as the mat separator 1c and the nonwoven separator 1d having a larger average pore diameter than this, it is necessary to pay attention to the balance of the pore volume (total pore volume) between the mat separator 1c made of glass fiber and the nonwoven fabric separator 1d. I found out that there is. Specifically, in a charge / discharge cycle in which the low-rate discharge capacity shows the maximum value, it is possible to control the state where the non-woven fabric separator 1d having a low electrolytic solution holding power (electrolytic solution is difficult to be introduced) is exhausted, It was determined that it is necessary to obtain sufficient output characteristics. As a result, the inventors have come up with the idea of optimizing the ratio A / B between the total pore volume A of the mat separator 1c and the total pore volume B of the nonwoven fabric separator 1d.

  Since the nonwoven fabric separator 1d is thinner than the mat separator 1c, the above-described configuration in which the ratio A / B is less than 5 indicates that the electrolyte is easily introduced into the nonwoven fabric separator 1d. In this configuration, the electrolytic solution stored in the nonwoven fabric separator 1d moves to the positive electrode plate 1a or the negative electrode plate 1b in which the electrolytic solution is more easily introduced (smaller average pore diameter) than the mat separator 1c. Then, the nonwoven fabric separator 1d depleted of the electrolytic solution can easily absorb the electrolytic solution from the adjacent mat separator 1c. By repeating this, if the electrolyte moves excessively from the mat separator 1c to the positive electrode plate 1a or the negative electrode plate 1b via the nonwoven fabric separator 1d, the battery reaction itself becomes difficult because the electrolyte is depleted from the mat separator 1c. As a result, the battery capacity (low rate discharge capacity) is reduced.

  On the other hand, the above-described configuration in which the ratio A / B exceeds 10 indicates that the electrolyte solution is difficult to be introduced into the nonwoven fabric separator 1d. In this configuration, the electrolyte in the nonwoven fabric separator 1d is easily depleted. Therefore, since there is no effect on the battery capacity (low-rate discharge capacity) itself from the beginning of the charge / discharge cycle, it is difficult to exchange ions across the nonwoven fabric separator 1d where the electrolyte is depleted. Characteristics (high-rate discharge characteristics) are deteriorated.

  Therefore, the above-described ratio A / B needs to be 5 or more and 10 or less.

  The thickness of the mat separator 1c is desirably 0.8 mm or greater and 1.4 mm or less. If this thickness is less than 0.8 mm, both separators are damaged in the manufacturing process of the electrode plate group, and an internal short circuit is somewhat likely to occur. If the thickness exceeds 1.4 mm, the output characteristics (high rate discharge characteristics) are somewhat higher. descend.

  The mat separator 1c may be made of ultrafine glass fiber. The nonwoven fabric separator 1d may be made of a fiber such as polypropylene or polyethylene and subjected to a hydrophilic treatment.

  Although Embodiment 1 is provided with a plurality of electrode plate groups 1 and a connecting component 4 for connecting the electrode plate groups 1 to each other, the present invention is applicable to a single electrode plate group 1 as well. It goes without saying that it is done.

Further, the total pore volume of the mat separator 1c and the nonwoven fabric separator 1d can be set to an arbitrary value by changing the weight depending on the amount of fibers per unit volume in addition to changing the thickness of the mat separator 1c and the nonwoven fabric separator 1d. be able to. This total pore volume is the mass of the dry state per separator located between the positive electrode plate and the negative electrode plate in the pore distribution measurement with a mercury porosimeter and the integrated pore volume (cm ³ / g) obtained by the measurement. It can be easily obtained by multiplying (g).

  Hereinafter, the effects of the present invention will be described with reference to examples.

  A positive electrode active material paste is prepared by kneading lead oxide powder with sulfuric acid and purified water, and this positive electrode active material paste is filled in a grid continuum obtained by expanding a lead alloy sheet and cut into a predetermined size. Thus, the positive electrode plate 1a was produced. On the other hand, a negative electrode active material paste is prepared by kneading an organic additive, barium sulfate, carbon, etc. added to lead oxide powder with sulfuric acid and purified water, and a lead alloy sheet is expanded. The obtained lattice was filled with this active material paste to produce a negative electrode plate 1b.

  A positive electrode plate 1a and a non-woven fabric separator are formed by facing a positive electrode plate 1a and a negative electrode plate 1b encapsulated in a bag-shaped non-woven fabric separator 1d (polypropylene fiber sulfonated) through a glass fiber mat separator 1c. The electrode plate group 1 adjacent in the order of 1d, mat separator 1c, and negative electrode plate 1b was produced.

  A plurality of electrode plate groups 1 were respectively stored in the cell chambers of the battery case 2, and different polarities of the adjacent electrode plate groups 1 were connected to each other by a connection component 4. The positive electrode plate 1a of the cell chambers at both ends was connected to the positive terminal 6 and the negative electrode plate 1b was connected to the negative terminal 6. The opening of the battery case 2 is sealed with a lid 3, an electrolytic solution (dilute sulfuric acid) is injected from the liquid port, the liquid port is sealed with a control valve 4, and a control valve type of 12V60Ah (3 hour rate capacity) Lead acid batteries A to M were produced. A battery N was prepared in the same manner as other batteries except that the nonwoven fabric separator 1d was not used.

  Various physical properties of the mat separators 1c and nonwoven fabric separators 1d of these batteries A to N will be described in detail in (Table 1) together with evaluation results of properties described later (all performed in an atmosphere at 25 ° C.).

  The above-described batteries A to N were charged and discharged repeatedly at a constant current charge of 1.5 A for 3 hours and a constant current discharge of 2.4 hours at 20 A until reaching 100 cycles. This 100 cycle is substantially the same as the charge / discharge cycle in which the lead storage battery used in this example has shown the maximum value of the low rate discharge capacity.

(Low rate discharge capacity)
In the next cycle in which 100 cycles of charge and discharge were performed under the above-described conditions, after the above charge, the battery was left in an open circuit state for 12 hours, and then a constant current discharge was performed until 20 V reached 9.9 V. The discharge capacity at this time is shown in Table 1 as a low rate discharge capacity.

(Output characteristics)
In the next cycle in which the low-rate discharge characteristics were evaluated, after the above-described charging, the battery was left in an open circuit state for 12 hours, and then a constant current discharge was performed until 150 V reached 8.4V. The value obtained by dividing the discharge capacity at this time by the low-rate discharge capacity is shown in Table 1 as a percentage of the output characteristics.

(Short circuit resistance)
100 batteries A to N were produced, and each open circuit voltage was measured 8 times in total every week, and an average value and a standard deviation were obtained each time. In each measurement, an open circuit voltage that is smaller than a value obtained by subtracting four times the standard deviation from the average value is regarded as a short-circuit battery, and the total number of short-circuit batteries in eight measurements is the total number of batteries (100). The incidence of short circuit failure was calculated. The occurrence rate of short circuit failure is shown in Table 1 as a measure of short circuit resistance.

  The batteries A to G are compared. When the ratio A / B between the total pore volume A of the mat separator 1c and the total pore volume B of the nonwoven fabric separator 1d is less than 5, the low-rate discharge capacity is remarkably reduced, and the output characteristics are somewhat reduced accordingly. descend. On the other hand, when the ratio A / B exceeds 10, the output characteristics are remarkably deteriorated. Therefore, it can be seen that the ratio A / B must be 5 or more and 10 or less.

  The battery D and the batteries H to K are compared. If the thickness of the mat separator 1c is less than 0.8 mm, both separators are damaged in the manufacturing process of the electrode plate group, and the internal short-circuit occurrence rate slightly increases. On the other hand, when the thickness of the mat separator 1c exceeds 1.4 mm, it becomes about 80% of the case where the high rate discharge capacity is 1.1 mm. Therefore, it can be seen that the thickness of the mat separator 1c is preferably 0.8 mm or more and 1.4 mm or less.

  The batteries C and E are compared with the batteries L and M. Since the difference in characteristics between the batteries C and L and the batteries E and M is not significant, the balance between the low rate discharge capacity after 100 cycles and the output characteristics is the ratio A of the total pore volume if the variation such as the thickness is small. It can be seen that / B dominates.

  The battery N is compared with other batteries. Even if the pore volume sufficient to store the electrolyte with only the mat separator 1c is provided, the short-circuit resistance is insufficient, and the ratio of the total pore volume is obtained after the mat separator 1c and the nonwoven fabric separator 1d are used in combination. It can be seen that unless A / B is optimized, low-rate discharge capacity / output characteristics and short-circuit resistance are not achieved.

  The lead acid battery of the present invention is highly advanced in terms of low rate discharge capacity / output characteristics and short circuit resistance, and is extremely useful industrially.

DESCRIPTION OF SYMBOLS 1 Electrode plate group 1a Positive electrode plate 1b Negative electrode plate 1c Matte separator 1d Non-woven fabric separator 2 Battery case 3 Lid 4 Connection component 5 Terminal

Claims (3)

Comprising at least one electrode plate group, an electrolyte, a battery case for storing these, a lid for sealing the opening of the battery case, and a control valve;
The electrode plate group includes a positive electrode plate, a negative electrode plate, and a separator separating them,
The separator further includes a mat separator made of glass fiber and a nonwoven fabric separator,
A lead acid battery, wherein the ratio A / B of the total pore volume A of the mat separator and the total pore volume B of the nonwoven fabric separator is 5 or more and 10 or less. The lead acid battery according to claim 1, wherein the mat separator has a thickness of 0.8 mm to 1.4 mm. The lead storage battery according to claim 1, further comprising a plurality of the electrode plate groups, and a connection component that connects the electrode plate groups to each other.

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