JP2011119197A - Gel-system lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of elongating life of a gel-system lead-acid battery. <P>SOLUTION: The gel-system lead-acid battery has an aqueous solution containing at least one out of a group consisting of polyvinyl alcohol, polyacrylate, and lignin by 3 to 12 wt.% arranged in contact with electrolyte of the gel-system lead-acid battery with diluted sulfuric acid as an electrolyte. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for extending the life of a gel-type lead storage battery to several times or more.

  In the gel type lead-acid battery, the dilute sulfuric acid, which is the electrolyte, is placed between the electrodes with a slightly higher concentration of 1.28 to 1.35 specific gravity immersed in silica gel. . If this battery is used for 3 to 6 months, water decreases and a part of the electrode does not come into contact with dilute sulfuric acid, thereby reducing the capacity of the battery. If this water further decreases, most of the electrodes will not come into contact with dilute sulfuric acid, and the battery life will be exhausted. We have found that polyvinyl alcohol, polyacrylate, and other compounds (hereinafter referred to as organic polymers), which have the effect of increasing the hydrogen overvoltage of the electrode in dilute sulfuric acid, are effective in eliminating the sulfation of deteriorated batteries and extending the life of new batteries. We discovered that there was a patent application (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

  Recently, gel-type lead-acid batteries that take advantage of the characteristics of gel-type lead-acid batteries that can make large-capacity batteries compact are often used in electric vehicles, electric buses, and the like. In this gel type lead-acid battery, dilute sulfuric acid, which is an electrolyte, is not contained in a fluid state, so the above-mentioned organic polymer aqueous solution is replenished by removing the lid of the battery case, and the electrolyte is evenly mixed. It was difficult to mix and adsorb to all electrode surfaces. That is, there was no suitable method for extending the life of the gel type lead-acid battery by using the above-mentioned organic polymer additive.

  JP 2000-149980 A   JP 2000-149981 A   JP 2001-313064 A

  The present invention provides means for extending the life of a gel-type lead-acid battery by adding a high-viscosity organic polymer high-concentration aqueous solution.

  In the present invention, a highly viscous organic polymer high-concentration aqueous solution is placed in contact with a gel containing an electrolytic solution, and the organic polymer is supplied to the electrode surface by gradually diffusing the polymer into the electrolytic solution over time. The first problem-solving means is based on the discovery that electrode sulfation can be prevented / recovered. At least one of the group consisting of polyvinyl alcohol, polyacrylate, and lignin is used. Is a gel-type lead acid battery in which an aqueous solution containing 3 to 12% by weight is placed in contact with the electrolyte solution of a gel-type lead acid battery using dilute sulfuric acid as an electrolyte.

  The second problem-solving means is an electrolyte solution for a gel-type lead acid battery using dilute sulfuric acid as an electrolyte solution containing an aqueous solution containing 3 to 12% by weight of at least one of the group consisting of polyvinyl alcohol, polyacrylate, and lignin. In the lead storage battery arranged in contact with the battery, the charging method of the gel-type lead lead storage battery in which auxiliary charging is performed in a state of a terminal voltage of 2.5 volts or more per unit cell.

  The operation of the first problem solving means is as follows. That is, conventionally, an appropriate concentration of an organic polymer such as polyvinyl alcohol or polyacrylic acid in an electrolyte is 0.01 to 1%. When excessively added, the internal resistance of the battery is increased, and the organic polymer is oxidatively decomposed. Undesirable phenomena such as foaming occurred. On the other hand, according to the first problem solving means, the organic polymer gradually diffuses in the high-viscosity liquid to reach the gel electrolyte, and gradually diffuses in the gel to the electrode surface. Therefore, the organic polymer concentration on the electrode surface is kept at a relatively low state, and the sulfation of the electrode can be prevented / recovered without causing an increase in internal resistance or foaming. Furthermore, since the high-concentration aqueous solution of the organic polymer used in the present invention has a high viscosity, even if impact or vibration is applied to the battery, the aqueous solution is prevented from scattering and does not hinder the use conditions of the battery.

  The operation of the second problem solving means is as follows. That is, the following means are preferable as the charging method in order to make the function of the first problem solving means sufficiently function. Conventional lead-acid batteries for automobiles consisting of 6-cell single cells usually have an upper limit of 14.5 volts (2.42 volts for single cells) for the purpose of preventing electrolyte reduction due to overcharge and water electrolysis. Charging methods have been taken. However, at this charging voltage, a considerable part of the negative electrode active material is reduced to lead metal, but part of it remains as lead sulfate crystals, and sulfation is insufficiently resolved. Slowly, undecomposed lead sulfate crystals accumulated and sulfation proceeded. In order to eliminate this sulfation, the region where the terminal voltage of the battery is less than 13.5 volts is charged with a large current of about 0.1 C, and then the charging voltage is 15 volts or more (2.5 volts or more for a single cell). This is achieved by performing supplementary charging with a small current of about 0.01 C for 10 to 30 hours. At this time, the organic polymer adsorbed on the electrode surface increases the hydrogen overvoltage of the electrode, and as a result, the generation of hydrogen due to the electrolysis of water is suppressed, so that the loss of moisture is also prevented. Here, C means a value of charging current (A) / battery rated capacity (AH), and in the case of a battery with a rated capacity of 40 AH, 0.01 C means a charging current of 0.4 A. .

  The effect of the first problem solving means is that the life of the gel type lead-acid battery, which has been about 3 to 6 months in the past, can be set to 1 to 3 years. Further, when the second problem solving means is used, the lifetime can be reduced to 5 to 10 by completely preventing sulfation and preventing electrolysis of the electrolytic solution.

  Graph of charge and battery terminal voltage   Cross-sectional view of a lead-acid battery showing the placement of a high concentration organic polymer aqueous solution   Cross-sectional view of a lead-acid battery showing another arrangement of organic polymer high-concentration aqueous solution

  As a method for supplying the organic polymer high-concentration aqueous solution to the gel electrolyte solution, as shown in FIG. 2, the high-viscosity aqueous solution 8 may be put on the gel electrolyte solution 7 as it is, but the diffusion rate is further reduced. Then, for the purpose of continuing the effect of the additive over a long period of time, as shown in FIG. 3, an organic polymer high-concentration aqueous solution is placed in a plastic container 9 provided with pores 10 at the boundary with the electrolytic solution. By diffusing the organic polymer through the pores, the diffusion rate can be arbitrarily controlled. Moreover, the viscosity of organic polymer high concentration aqueous solution can also be adjusted by selecting the polymerization degree of organic polymer. The concentration of the organic polymer high-concentration aqueous solution is preferably 3% by weight or more, more preferably 4% by weight or more in terms of imparting a viscosity that effectively prevents scattering due to vibration or impact. Moreover, in order to prevent the restriction | limiting of handling, such as film formation accompanying drying, the density | concentration of organic polymer high concentration aqueous solution has preferable 12 weight% or less, and its 10 weight% or less is more preferable. The polyacrylate of the present invention means salts such as sodium polyacrylate and potassium polyacrylate.

  The supplementary charging performed in the present invention applies a high voltage in order to completely electrolyze the remaining lead sulfate with the hydrogen overvoltage of the negative electrode increased by the action of the organic polymer. In curve 1 showing the relationship with voltage, after charging in region 2 where the upper limit is 14.5 volts per 6 cells, which is a normal charge, it is performed for a long time at a low current with little hydrogen generation. It is preferable to carry out in the region 3 where the terminal voltage is about 15 to 16 volts. The supplementary charging time is practically 10 to 30 hours, but is not limited thereto. This supplementary charging condition is the most characteristic feature of the present invention. In the conventional charging, the electrolysis of water is intense and impossible to carry out. It is possible for the first time by carrying out while suppressing.

  A gel type lead-acid battery having a rated capacity of 100 AH having a structure of FIG. 2 in a single cell, an electrolytic solution 7 in which a negative electrode 5 and a positive electrode 6 are contained in a battery 4 and dilute sulfuric acid having a specific gravity of 1.32 is contained in silica gel. And 100 ml of an aqueous solution with a polyvinyl alcohol concentration of 8% by weight were placed on top of them and brought into contact with the electrolyte solution 7. This battery is used under the condition of discharging about 50% once a day. Charging is performed at the first stage of 30 amperes (0.3C) up to 14.5 volts and then connected at 3 amperes (0.03C). About 10 to 25 hours of supplementary charging (second stage charging) was performed until the voltage reached 15.5 volts. As a result, the battery that has been degraded to 50% or less of the rated capacity in about 6 months can be used at 50% or more of the rated capacity for 5 years or more.

  For a 12 volt, 17 AH gel-type lead acid battery that has been used in an electric vehicle for 6 months and the capacity has dropped to 50% or less of the rated capacity, a 5% aqueous solution of polyvinyl alcohol on the gel-type electrolyte is 35 per cell. As a result of adding 1 milliliter at a time and charging 14.5 volts as the upper limit and discharging until the electric car stopped working once a day, the battery capacity was restored to 80% of the new battery after 14 days.

7: Electrolytic solution 8: Aqueous solution

Claims (2)

  An aqueous solution containing 2 to 10% by weight of at least one of the group consisting of polyvinyl alcohol, polyacrylate and lignin is disposed in contact with the electrolyte of a gel-type lead storage battery using dilute sulfuric acid as an electrolyte. Gel type lead acid battery.   In a lead storage battery in which an aqueous solution containing 2 to 10% by weight of at least one of the group consisting of polyvinyl alcohol, polyacrylate, and lignin is placed in contact with the electrolyte of a gel type lead storage battery using dilute sulfuric acid as an electrolyte, A method for charging a gel-type lead-acid storage battery, wherein auxiliary charging is performed with a terminal voltage of 2.5 volts or more per unit cell.

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