JPH0869812A - Sealed lead-acid battery and its manufacture - Google Patents

Abstract

PURPOSE: To lengthen the battery service life by restraining a charging current low at trickle charging time even if discharge capacity is increased by heightening porosity of a negative electrode active material of a sealed lead-acid battery. CONSTITUTION: Porosity of an active material layer of an outside surface 3 of a negative plate 2 positioned on an end surface of a plate group 1 is set lower than porosity of an active material layer of an inside surface 4. That is, porosity of the active material layer of the outside surface 3 of the negative plate 2 facing an inner wall of a battery jar 5 is set lower than the porosity of the active material layer of the inside surface 4. The negative plate 2 is manufactured by heating in such a way that a paste-like negative electrode active material to which a thermally expansive microcapsule is added is filled in one surface of a lead alloy grid body and a paste-like negative electrode active material to which the thermally expansive microcapsule is not added is filled in the other surface. Remains of the active material from which the low boiling point hydrocarbon in the thermally expansive microcapsule is gasified and is gone become pores, and porosity of the active material layer becomes high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed lead acid battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a cathode plate of a sealed lead-acid battery, a grid body filled with the same active material is used. When a cathode plate having a high porosity of the active material is used to increase the discharge capacity, the oxygen gas absorption reaction generated during charging becomes excessive on the outer surface of the cathode plate located outside the electrode group. However, there is a problem that the charging current during trickle charging becomes high. This is because the outer surface of the cathode plate located outside the electrode plate group is likely to come into contact with oxygen gas, and the high porosity of the active material makes the contact area with oxygen gas wide.

[0003]

The problem to be solved by the present invention is to reduce the charging current during trickle charging even if the porosity of the cathode active material of the sealed lead-acid battery is increased to increase the discharge capacity. It is to suppress and prolong battery life.

[0004]

A sealed lead-acid battery according to the present invention for solving the above-mentioned problems forms a plate group by alternately stacking a cathode plate and an anode plate via a retainer, In a sealed lead-acid battery housed in a battery case, a cathode plate is located on the outermost side of the electrode plate group, and the porosity of the active material layer on the inner surface of the cathode plate is relative to the porosity of the active material layer on the outer surface. It is characterized by being made higher. The method for manufacturing a sealed lead-acid battery according to the present invention, a cathode plate and an anode plate are alternately stacked via a retainer to form an electrode plate group, and in a method of storing this in a battery case, one of the grids The surface is filled with a paste-like cathode active material containing thermally expandable microcapsules, the other surface of the lattice is filled with a paste-like cathode active material containing no thermally expandable microcapsules, and then through a heating step. Prepare the manufactured cathode plate. The cathode plate is used as the outermost cathode plate of the electrode plate group, and the surface not containing the thermally expandable microcapsules is the outside surface.

[0005]

In the sealed lead acid battery according to the present invention, the porosity of the active material layer on the outer surface (the surface most likely to come into contact with oxygen gas) of the cathode plate located on the outermost side of the electrode plate group is higher than that on the inner surface. Since it is low, the contact area with oxygen gas is narrowed and the absorption reaction of oxygen gas is suppressed. As a result, the charging current during trickle charging is also low. Heat the cathode plate filled with the paste-like cathode active material containing the heat-expandable microcapsules only on one surface of the lattice body and the paste-like cathode active material not containing the heat-expandable microcapsules on the other surface. By the treatment, it is possible to easily manufacture a cathode plate in which the porosity of the active material layer on one surface is relatively higher than the porosity of the active material layer on the other surface.

[0006]

【Example】

(Example) An anode plate group for one cell was constituted by five anode plates and six cathode plates, and a sealed lead-acid battery having 3V and 6V and a rated capacity of 6Ah was assembled. Outermost of the electrode group (both end surfaces)
The two cathode plates located at were used as follows. That is, heat-expandable microcapsules (trade name “Matsumoto Microsphere EF”, Matsumoto Yushi-Seiyaku Co., Ltd.)
1% by weight of a paste-like cathode active material added thereto is filled into one surface of the lead alloy grid to have a thickness of 1.0 mm. The other surface of the grid is filled with a paste-like cathode active material containing no thermally expandable microcapsules in a thickness of 1.0 mm. The heat-expandable microcapsules used are 80
When heated to 0 ° C., the low boiling point hydrocarbon contained therein expands, the capsule breaks after the initial diameter of several μm to several tens of μm, and the vaporized low boiling hydrocarbon escapes. The cathode plate manufactured as described above was heated at 100 ° C. for 2 hours.
When heated for a minute, the low boiling point hydrocarbons in the heat-expandable microcapsules were vaporized and the traces that had escaped from the active material became pores, and the porosity of the active material layer became 65%. On the other hand, the porosity of the active material layer on the side to which the heat-expandable microcapsules were not added was 55%. Note that the material of the microcapsules after the bubbles have escaped contracts and remains in the pores of the active material layer, but this does not adversely affect the battery performance. On both end faces of the electrode plate group, the above-mentioned cathode plates were arranged with the side having a low porosity of the active material layer as the outer face. The other four cathode plates constituting the electrode plate group use the active material to which the thermally expandable microcapsules are not added. The porosity of the active material layer is 55%. The dimensions of these cathode plates are 66 mm in length, 44 mm in width, and 2 mm in thickness. FIG. 1 shows the structure of this sealed lead-acid battery. Cathode plate 2 located on the end surface of electrode plate group 1
The porosity of the active material layer on the outer surface 3 is lower than the porosity of the active material layer on the inner surface 4. That is, the porosity of the active material layer on the outer surface 3 of the cathode plate 2 facing the inner wall of the battery case 5 is lower than the porosity of the active material layer on the inner surface 4.
Although not shown, the porosity of the active material layer on the outer surface 3 of the cathode plate 2 facing the partition wall of the battery case 5 is lower than the porosity of the active material layer on the inner surface 4 as well.

(Comparative Example) 1 heat-expandable microcapsule
The paste-like cathode active material added by wt% was filled on both sides of the lead alloy grid, and the cathode plate which was heat treated in the same manner as in the example was used for both end faces of the electrode plate group, and 6 V consisting of 3 cells, rated. A sealed lead-acid battery with a capacity of 6 Ah was assembled.

(Conventional example) A cathode plate in which both sides of a lead alloy grid body are filled with a paste-like cathode active material containing no thermally expandable microcapsules is used for both end faces of an electrode plate group, and 6 V consisting of 3 cells is used. , A sealed lead acid battery with a rated capacity of 6 Ah was assembled.

A comparison of the initial capacities of the above sealed lead-acid batteries is shown in Table 1 by taking the conventional example as 100. The measurement of the initial capacity was performed at a set voltage of 7.35 V (limited current of 1.8 A (0.3
C)) was charged for 6 hours and then discharged to a final voltage of 5.1 V with a current of 1.0 A.

[0010]

[Table 1]

Next, each of the above sealed lead-acid batteries is covered with an acrylic resin case, placed in each of the constant temperatures of 25, 50, 60, and 80 ° C. and charged at a constant voltage of 2.3 V / cell (trickle charge). Then, the trickle charge current was measured. Fig. 2 shows the trickle charge current at each temperature as 1 when the temperature is 25 ° C.
It was shown to. Although the sealed lead-acid battery of the embodiment has a larger battery capacity than the conventional one, the trickle charge current does not increase so much. Since the charging current does not rise, the phenomenon of heat escape is suppressed.

[0012]

As described above, in the sealed lead-acid battery according to the present invention, the trickle charge current can be kept low while increasing the discharge capacity by increasing the porosity of the active material of the cathode plate, so that the thermal escape of heat can be prevented. The phenomenon can be suppressed and the battery life can be prolonged.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a main part of a sealed lead-acid battery in an example according to the present invention.

FIG. 2 is a curve diagram showing a relationship between an ambient temperature and a trickle charging current when a sealed lead-acid battery is trickle charged.

[Explanation of symbols]

 1 is an electrode plate group 2 is a cathode plate 3 is an outer surface 4 is an inner surface 5 is a battery case

Claims (2)

[Claims] 1. A sealed lead acid battery in which a cathode plate and an anode plate are alternately stacked via a retainer to form an electrode plate group, and the electrode plate group is housed in a battery case. And the porosity of the active material layer on the inner surface of the cathode plate is made relatively higher than the porosity of the active material layer on the outer surface. 2. In the manufacture of a sealed lead-acid battery in which a cathode plate and an anode plate are alternately stacked via a retainer to form an electrode plate group, and the electrode plate group is housed in a battery case, one surface of a grid body is provided. Filled with a paste-like cathode active material containing a thermally expandable microcapsules, the other surface of the lattice is filled with a paste-like cathode active material containing no thermally expandable microcapsules, then the cathode manufactured through a heating step A sealed lead-acid battery characterized in that a plate is prepared, the cathode plate is used as the cathode plate located at the outermost side of the electrode plate group, and the surface not containing the thermally expandable microcapsules is the outer surface. Manufacturing method.