JP4876302B2 - Sealed lead acid battery - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a sealed lead-acid battery, and more particularly to an improvement in its safety valve.
[0002]
[Prior art]
An example of a conventional safety valve structure for a sealed lead-acid battery is shown in FIG. This structure is a structure in which airtightness is maintained by covering the tip of the pipe-shaped exhaust port 2 provided in the battery case lid 1 with a cap-type rubber valve 3. And when the pressure inside the battery rises due to the gas generated inside the lead-acid battery, the safety valve with such a structure opens the cap-type rubber valve to prevent the battery case made of synthetic resin from cracking, and the gas from the exhaust port When the pressure in the battery decreases when left unattended, etc., the cap-type rubber valve is in close contact with the pipe-shaped exhaust port and operates to prevent outside air from entering the lead-acid battery.
[0003]
In a sealed lead-acid battery having a safety valve having a structure in which such an exhaust port is sealed with a rubber valve, chloroprene rubber, EPDM rubber or the like has been used as a rubber valve material, but from the viewpoint of acid resistance and the like. Recently, the use of EPDM rubber is increasing.
[0004]
Further, in order to improve the airtightness of the safety valve or prevent the rubber valve from being deteriorated, silicon oil or fluorine oil is applied to the rubber valve as a sealing oil.
[0005]
[Problems to be solved by the invention]
Silicone oil that has been conventionally applied to rubber valves has the characteristics that the vapor pressure is relatively high and the oil will evaporate after long-term use. For this reason, it has a structure in which silicon oil is applied to the rubber valve. In the battery, there is a problem that the rubber valve deteriorates early, the safety valve does not operate at a predetermined pressure, the internal pressure rises, and the battery case bulges or cracks.
[0006]
On the other hand, when fluorine oil is used, if it is applied to a rubber valve made of chloroprene rubber, the components in the rubber are eluted in the oil, which causes the problem of accelerating the deterioration of the rubber valve. However, depending on the type of fluorine oil, there is a problem that the self-discharge rate of the battery is increased.
[0007]
An object of the present invention is to solve the above problems and provide a battery having excellent durability.
[0008]
[Means for Solving the Problems]
The present invention is a sealed lead-acid battery having a safety valve having a structure in which an exhaust port is sealed with a rubber valve, wherein the rubber valve is made of EPDM rubber, and the rubber valve has no fluorine in the molecular structure. There are applied, the fluorine oil are those, wherein the carbon, fluorine, Oh Rukoto in perfluoropolyether oils consisting of oxygen only.
[0009]
As a result of various investigations on the oil applied to the rubber valve, the present invention shows that the fluorine oil has a relatively low vapor pressure, and that the above problem that occurs when using the fluorine oil is included in the molecule of the fluorine oil It was made by finding out that some chlorine was the cause. Then, by applying a fluorine oil that does not contain chlorine in the molecular structure to the rubber valve, the above-described problems can be solved and a battery having excellent durability can be realized.
[0010]
In addition, as a fluorine oil which does not contain chlorine in the molecule | numerator, the perfluoropolyether type oil which consists only of carbon, a fluorine, and oxygen is especially preferable. This is because such a fluorine oil is cheaper than, for example, a fluorine oil composed of only carbon and fluorine, and has excellent chemical resistance and performance such as compatibility with a rubber valve and a battery case resin. It is.
[0011]
In addition, as a material of the rubber valve to which the fluorine oil not containing chlorine in the molecule is applied, EPDM rubber is particularly preferable, and the perfluoropolyether oil composed only of carbon, fluorine, and oxygen is applied to the EPDM rubber. More preferred. This is because the reactivity between rubber and fluorine oil can be further suppressed, and the durability can be further enhanced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described together with examples.
[0013]
The sealed lead-acid battery of the present invention is a sealed lead-acid battery having a safety valve having a structure in which an exhaust port is sealed with a rubber valve, but as the safety valve structure, for example, the structure shown in FIG. 1 can be used as it is. As a matter of course, the size of the rubber valve varies depending on the size of the pipe-shaped exhaust port.
[0014]
The following is an example when the present invention is applied to a sealed lead-acid battery of 2V, 200 Ah.
[0015]
The structure of the safety valve is the same as that shown in FIG. The material of the cap-type rubber valve 3 is EPDM rubber, and its inner diameter is slightly smaller than the outer diameter of the pipe-like exhaust port 2. The EPDM rubber used had a shear hardness of 45, the cap type rubber valve 3 had a diameter of 11.5 mm, a side wall thickness of 1.0 mm, a top wall thickness of 1.8 mm, a height of 6.0 mm, and a pipe-shaped exhaust port 2 Are 12 mm in diameter and 10 mm in height. As the sealing oil (oil applied to the rubber valve), perfluoropolyether oil shown in the following Table 1 (which is a table showing the molecular formula of the applied oil) was used. For comparison, batteries using silicon oil and fluorine oil (chlorine-containing) were produced in place of the perfluoropolyether oil.
[0016]
[Table 1]
For these three types of batteries, a float test was conducted at 60 ° C. and 2.23 V / cell for one year, and a capacity test was conducted every two months. In addition, after the float test, the on-off valve pressure of the safety valve was measured to investigate whether or not it normally operated. The capacity transition during the float test is shown in FIG.
[0017]
In the battery coated with silicone oil, the safety valve did not operate normally, and the discharge capacity was reduced even in the float test. This is because the oil evaporates with the passage of the test period, the rubber valve does not operate normally, the airtightness is lost, and external air enters the battery.
[0018]
In the battery coated with fluorine oil (containing chlorine), the discharge capacity decreased early, but the rubber valve operated normally. This was because the fluorine oil (chlorine-containing) applied to the rubber valve entered the battery, adversely affecting the battery performance.
[0019]
In contrast, batteries with perfluoropolyether-based oils operate normally even after a one-year float test, and the discharge capacity is about 80%, which is a lower discharge capacity than batteries with other oils. It was found to be an excellent oil.
[0020]
The vapor pressures of the various oils used above are shown in FIG. It can be seen that perfluoropolyether oil has a lower vapor pressure than other oils and is difficult to evaporate.
[0021]
FIG. 4 shows the influence of the various oils used above on the battery performance when mixed into the electrolyte. This figure shows the transition of terminal voltage when 2wt% of the various oils shown in Table 1 are added to a sealed lead battery of 2V, 50Ah and a standing test is performed at 60 ° C. Was regarded as the self-discharge rate.
[0022]
The terminal voltage of silicon oil and perfluoropolyether oil was 2 V or more after 40 days, but the fluorine oil (containing chlorine) was 1.5 V or less on the 10th day. This was because chlorine in the molecular structure was liberated from the oil, increasing the self-discharge rate.
[0023]
Table 2 below summarizes the test results for the batteries using the various oils.
[0024]
[Table 2]
From the above results, it was found that in the battery of the present invention example using perfluoropolyether oil, the operating state of the safety valve is excellent, and further, the battery characteristics are not deteriorated due to the oil mixed in the battery.
[0025]
In the above embodiment, the perfluoropolyether-based oil has a structure having a side chain. However, the perfluoropolyether-based oil is not limited to this, and is a perfluoropolyether-based oil composed only of carbon, fluorine, and oxygen. If oil is used, the same effect as that obtained by the battery of the above-described embodiment can be obtained.
[0026]
【Effect of the invention】
According to the sealed lead acid battery of the present invention in which a rubber valve of EPDM rubber is coated with a perfluoropolyether-based oil consisting only of carbon, fluorine and oxygen, which is a fluorine oil that does not contain chlorine in its molecular structure. An excellent battery can be obtained, the adverse effect of the oil on the battery performance can be greatly reduced, and the on-off valve operating pressure can be stably maintained even when used for a long period of time, almost unchanged from the initial state.
[Brief description of the drawings]
FIG. 1 is a view showing an example of a safety valve structure for a sealed lead-acid battery.
FIG. 2 is a graph showing a change in capacity during a 60 ° C. float test.
FIG. 3 is a diagram showing vapor pressures of various oils.
FIG. 4 is a graph showing changes in terminal voltage when a standing test is performed at 60 ° C.
[Explanation of symbols]
1. Battery case lid 2. 2. Pipe-shaped exhaust port 3. Cap type rubber valve Terminal

Claims (1)

A sealed lead-acid battery having a safety valve with a structure in which the exhaust port is sealed with a rubber valve , and the rubber valve is made of EPDM rubber, and the rubber valve is coated with fluorine oil that does not contain chlorine in the molecular structure. cage, sealed lead-acid battery wherein the fluorinated oil is characterized atoms, fluorine, Oh Rukoto in perfluoropolyether oils consisting of oxygen only.