JP2737227B2 - Sealed lead-acid battery - Google Patents

Description

The present invention relates to a thin sealed lead-acid battery.

[Prior Art] A general sealed lead-acid battery is configured by arranging, in a battery case, an electrode group in which a required number of cathode plates, separators and anode plates are sequentially stacked. 2. Description of the Related Art In recent years, sealed lead-acid batteries have been widely used in portable devices, portable power supplies, emergency power supplies, and the like, and there has been a strong demand for thinner batteries. Therefore, a thin active material layer is formed on a current collector consisting of a sheet-like lead plate or lead alloy plate to form an anode plate and a cathode plate. There has been proposed a sealed lead-acid battery having a configuration in which an electrolyte holding member impregnated with a liquid electrolyte is arranged.

[Problems to be Solved by the Invention] In a sealed lead-acid battery, when overcharged, water decomposition occurs and oxygen gas is generated from the anode plate. This oxygen gas is absorbed by the cathode plate and reacts with Pb of the cathode active material to form PbO. This PbO reacts with H ₂ SO ₄ of the electrolytic solution to generate PbSO ₄ and H ₂ O. Therefore reduction of water is not, has a mechanism that does not occur generation of H ₂ gas from the cathode plate. Oxygen gas generated from the anode plate as described above must be absorbed by the cathode plate through the electrolyte. However, in the above-described thin sealed lead-acid battery, the entire surface of the active material layer is covered with an electrolyte holder impregnated with the electrolyte, and the back surface of the active material layer is a sheet-like current collector. Due to the close contact, there was a problem that oxygen gas was not sufficiently absorbed by the cathode plate during charging.

An object of the present invention is to provide a thin sealed lead-acid battery that can solve the above problems.

[Means for Solving the Problems] According to the present invention, a cathode active material layer is formed on a cathode current collector, and an anode active material layer is formed on an anode current collector. The present invention is directed to a sealed lead-acid battery including an electrode group in which an electrolyte holder is disposed between a material layer. In the present invention, a separator having a predetermined shape having acid resistance and water repellency is disposed between the cathode active material layer and the anode active material layer. The separator contacts a part of the cathode active material layer and the anode active material layer to form a plurality of separation spaces between the cathode active material layer and the anode active material layer. Then, the electrolyte holder is held in the plurality of separation spaces.

When the separator is configured so that a plurality of separation spaces formed by the separator are dispersed in the vertical direction, the electrolyte holder is divided into a plurality, and the difference in concentration of the electrolyte when viewed as a whole is small. Become.

If a separator is used in which at least one of a plurality of through holes and grooves is uniformly dispersed and formed in a separator sheet, a separation space for holding an electrolytic solution holding member is evenly dispersed and disposed over the entire surface of the active material layer. Can be.

The electrolyte holder may be a nonwoven fabric made of glass fiber impregnated with an electrolyte, but may be formed into a gel or paste by adding sulfuric acid to a solution in which powder such as diatomaceous earth or silica particles is dispersed. A liquid holder can be used.
When a gel or paste-like electrolyte holder is used, the electrolyte holder may be filled into the separation space by screen printing.

[Action] Since the electrolytic solution is not impregnated into the separator having acid resistance and water repellency, the electrolytic solution does not exist on the surface portion of the active material layer which comes into contact with the separator. Further, since the separator and the electrolyte holder are different and the separator has water repellency, an oxygen gas passage is formed between the separator and the electrolyte holder. Therefore, the oxygen gas generated at the anode plate is
The surface of the active material layer where the electrolyte does not exist is absorbed by the surface of the active material of the cathode plate through the passage between the separator and the electrolyte holder. Therefore, unlike the conventional case, most of the oxygen gas does not substantially pass through the electrolytic solution, so that the oxygen gas is absorbed well. As a result, the internal pressure in the battery becomes smaller than in the prior art.

When one electrolytic solution holding body (retainer) is used as in the related art, a relatively large difference occurs in the concentration of the electrolytic solution between above and below the electrolytic solution holding body. When the separator is configured to disperse the plurality of separation spaces in the vertical direction and the electrolyte holder is dispersed in the vertical direction, a difference in the concentration of the electrolyte in the electrolyte holder in each separation space occurs. Become. Therefore, as a whole, the difference in the concentration of the electrolyte is smaller than in the conventional case.

When a separator in which at least one of the plurality of through-holes and grooves is uniformly dispersed is used as a separator, an oxygen gas passage can be formed evenly between the cathode active material layer and the anode active material layer. , Gas absorption can be performed very well.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an exploded perspective view of the sealed lead-acid battery of the present invention. In the figure, reference numerals 1 and 2 denote film-shaped or sheet-shaped synthetic resin bodies, which are formed from a heat-sealable synthetic resin such as polyethylene. On the synthetic resin bodies 1 and 2, film-shaped or sheet-shaped current collectors 3 and 4 made of lead or lead alloy and having terminal portions 3a and 4a, respectively.
Are bonded by an epoxy resin adhesive.

On the current collectors 3 and 4, a paste-like anode active material material and a cathode active material material are applied by screen printing, respectively, and subjected to an appropriate treatment to thereby form the anode active material layer 5
And a cathode active material layer 6. The paste-like active material is produced by kneading lead powder, water and sulfuric acid. The paste-like active material applied by the screen printing method is dried, then ripened, formed, washed with water, and dried to become the anode active material layer 5 and the cathode active material layer 6, respectively.

Between the anode active material layer 5 and the cathode active material layer 6, the separator 7 and the group of electrolyte holders 8 are arranged so as to be in contact with the surfaces of both active material layers. The separator 7 has insulating properties,
It is formed of a fluororesin or the like having acid resistance and water repellency. The separator 7 used in this embodiment is formed in a zigzag shape by connecting two adjacent horizontal rails 7a sequentially with vertical rails 7b. The separator 7 forms separation spaces 9a to 9d composed of four rectangular grooves distributed in the vertical direction by the horizontal rails 7a.

Then, in these separation spaces 9a to 9d, four electrolytic solution holders 8a to 8d are stored and held. As these electrolyte holders 8a to 8d, for example, a non-woven fabric made of glass fiber impregnated with a gel electrolyte can be used. Also, when the separation space is reduced by increasing the number of the crosspieces 7a, a gel or paste-like electrolyte holding body is formed by adding sulfuric acid to a solution in which powder such as diatomaceous earth or silica particles is dispersed. The separation spaces 9a to 9d can be filled using a printing method. When the screen printing method is used, the electrolytic solution holding member may be filled in a state where the separator 7 is arranged on one of the active material layers.

The battery case is formed by heat-welding the periphery of the polymerized synthetic resin bodies 1 and 2. When making a battery case,
An unwelded part can be formed in a part and used as a gas vent part.

2A to 2C show modified examples of the separator. The separator 71 in FIG. 2 (A) has a comb-like shape, and a separation space formed of a rectangular groove is formed between the two cross rails 71a, similarly to the separator 7 used in the embodiment of FIG. Is done. FIG. 2 (B) shows a plurality of diamond-shaped through holes and grooves 72 forming a separation space in the separator sheet.
2A shows an expanded separator 72 formed almost evenly, and FIG. 2 (C) shows hexagonal through holes and grooves 73a forming a separation space almost uniformly. This shows a formed honeycomb separator 73. The separators 72 and 73 shown in FIGS. 2 (B) and 2 (C) are suitable for filling the electrolyte holder by a screen printing method, and a plurality of separation spaces are formed by small through holes or grooves 72a and 73a. When formed, a gas passage can be formed evenly over the entire surface of the active material layer. The shapes of the through holes and the grooves for forming the separation space are arbitrary.

In order to compare the performance of the battery of the present invention with the performance of a conventional battery, a storage battery having the structure shown in FIG. 1 and a conventional storage battery using one electrolytic solution holder (retainer) were prepared. A battery internal pressure test was performed. The condition of the battery internal pressure test is a change in battery internal pressure during charging after discharging, and the charging condition is 1c.
It was a 2.5V / cell constant current constant voltage charge with a cut. The results of the battery internal pressure test were as shown in FIG.

In FIG. 3, A shows the change in the internal pressure of the battery of the present invention, and B shows the change in the internal pressure of the conventional battery. As can be seen from the results, in the battery A manufactured by the method of the present invention, the internal pressure of the battery is considerably low, and the absorption of oxygen gas is good. When a separator of the type shown in FIGS. 2 (B) and 2 (C) is used, the absorption of oxygen gas is further improved, and the internal pressure can be further reduced.

The above embodiment is a unit cell sealed lead storage battery,
The present invention is not limited to a unit cell. Further, in the above embodiment, the battery case is formed of the synthetic resin bodies 1 and 2 which can be welded by heat, but a battery case of another configuration can be used.

[Effects of the Invention] According to the present invention, oxygen gas absorption in a cathode plate can be made better than before, and life characteristics can be improved,
Moreover, the internal pressure during overcharge can be reduced.

In addition, when the separator is configured to disperse the plurality of separation spaces in the up-down direction and the electrolyte holder is dispersed in the up-down direction, the difference in the concentration of the electrolyte as a whole can be reduced as compared with the related art.

In addition, when a separator in which at least one of a plurality of through-holes and grooves is uniformly dispersed and formed in a separator sheet is used, an oxygen gas passage is uniformly formed between the cathode active material layer and the anode active material layer. It is possible,
Gas absorption can be performed very well.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a sealed lead-acid battery according to one embodiment of the present invention, and FIGS. 2 (A) to 2 (C) are perspective views each showing a schematic configuration of a separator used in another embodiment of the present invention. Third
The figure is a diagram showing a change in battery internal pressure at the time of charging the conventional sealed lead storage and the sealed lead storage of the present invention. 1,2: synthetic resin body, 3,4: current collector, 5: anode active material layer, 6: cathode active material layer, 7,71,72,73 ... separator,
72a, 73a: through-holes and grooves, 8a to 8d: electrolyte holder, 9
a ～ 9d …… Separation space.

Claims (3)

(57) [Claims] A cathode active material layer is formed on a cathode current collector, an anode active material layer is formed on an anode current collector, and an electrolytic solution is formed between the cathode active material layer and the anode active material layer. In a sealed lead-acid battery provided with an electrode group in which a liquid holding member is arranged, a part of the cathode active material layer and the anode active material layer in contact with the cathode active material layer and a part of the anode active material layer. A separator having acid resistance and water repellency that forms a plurality of separation spaces is disposed between the cathode active material layer and the anode active material layer, and the electrolyte holder is held in the plurality of separation spaces. A sealed lead-acid battery. 2. The sealed lead-acid battery according to claim 1, wherein the separator is configured such that the plurality of separation spaces are vertically dispersed. 3. The sealed lead-acid battery according to claim 1, wherein the separator is formed by uniformly forming at least one of a plurality of through holes and grooves in a separator sheet.