JP2536251B2 - Lead acid battery - Google Patents

Description

The present invention relates to a lead storage battery using a paste type cathode plate and an anode plate.

[Prior Art] When increasing the capacity of a conventional lead battery, the porosity of the active material is increased by increasing the amount of water in the paste or the amount of lead sulfate (PbSO ₄ ) to reduce the density of the paste. There was a way to make it happen.

[Problems to be Solved by the Invention] Although the total pore volume (porosity) can be controlled by controlling the water content or the lead sulfate content in the paste as described above, It is difficult to define the distribution of pores only by controlling the amount.

Generally, the pore distribution of the anode active material has two peaks as shown in FIG. Here, the large pores are macropores, and the small pores are micropores. 0.2 here
The pores with a size of μm or more are defined as macropores, and the pores with a size of less than 0.2 μm are defined as micropores.

Macropores are used as pores between PbO ₂ mother particles, and micropores are used.
With pores between the child particles constituting the PbO ₂ mother particles, in the conventional method of decreasing the density of the anode active material by increasing the amount of water or the amount of lead sulfate in the paste, the increase of micropores is seen, Macropores hardly increase. That is, the child particles are more coarsely gathered than in the conventional case to form the mother particles, but the macropores hardly increase. Therefore, the liquid diffusion inside the electrode plate is delayed during the discharge reaction, and the reaction is concentrated on the surface of the electrode plate. Also, since there are many micropores, PbO _{2 on the} surface of the electrode plate
The utilization rate of the mother particles increases, and the capacity increases accordingly. However, when the cycle life test is performed, the active material on the surface of the electrode plate is repeatedly charged and discharged locally, so that the volume change due to the expansion and contraction reaction becomes large, and the active material becomes muddy at an early stage to shorten the life.

Also, if the density of the paste is reduced by simply increasing the amount of water or the amount of lead sulfate, the viscosity of the paste will decrease, and there will be a limit in the filling properties of the paste, so the porosity cannot be increased so much.

The object of the present invention is to reduce the pore volume of the micropores, increase the pore volume of the macropores to suppress the mudification of the active material, and reduce the density of the anode active material without impairing the filling property of the paste. The purpose is to provide a lead-acid battery with a long life.

[Means for Solving the Problems] The present invention has been made to achieve the above object, and in the present invention, the total pore volume is in the range of 0.16 to 0.18 cc / g, and the diameter is less than 0.2 μm. An anode active material having a pore volume of 0.02 cc / g or less and a pore volume of 0.2 to 4.0 μm and a volume of 0.13 cc / g or more is used.

An anode plate provided with an anode active material having a pore distribution as described above uses a lead oxide having a smaller particle diameter than that of a conventional lead oxide as a raw material of an electrode plate of a lead storage battery, and the lead oxide is mixed with a prescribed amount of water. It is obtained by filling a current collector with a paste kneaded with and dilute sulfuric acid, and then performing ordinary drying and chemical conversion steps.

[Operation] When lead sulfate having a smaller particle size than the conventional one is used as a raw material for the anode active material, even if the PbO ₂ mother particle is about the same size as the conventional one, the PbO ₂ child particle constituting the mother particle is formed. Is smaller than before. Therefore, the pore volume of the micropores between the particles decreases, and conversely, the pore volume of the macropores increases.

That is, since the pore volume of the micropores is smaller than that of the conventional one, and the pore volume of the macropores is large, the liquid is smoothly diffused into the electrode plate during the discharge reaction, and the surface of the electrode plate is evenly used inside. In addition, if the utilization ratio of all active materials is the same, the utilization ratio of one PbO ₂ mother particle will be lower than in the past.
Therefore, the change in volume due to repeated charging and discharging (due to the PbO ₂ PbSO ₄ reaction) is small, so that mud formation is delayed and the life is extended.

Further, since lead oxide having a small particle size is used as a raw material, even when the paste density is reduced, the paste viscosity can be maintained at the same level as the conventional one, and the porosity can be sufficiently increased.

[Example] In the conventional lead-acid battery, the median diameter of lead oxide, which is a raw material of the anode active material, was about 2 μm, but in this example, the median diameter of lead oxide is the conventional lead oxide (metal Pb remains. )
A lead plate was prepared by a conventional manufacturing method using lead oxide having a thickness of 1 μm, which is about ½ of the above.

In order to compare the performances of a conventional lead storage battery (referred to as a conventional product) and a lead storage battery according to the present invention (referred to as a product of the present invention), as a conventional lead storage battery, a conventional product A and a paste of an anode active material are used. Conventional product B whose density is about 15% lower than that of conventional product A
And prepared. In both the conventional products A and B, the median diameter of lead oxide, which is a raw material of the anode active material, is about 2 μm.

In the product of the present invention, as in the case of the conventional product B, the density of the paste of the anode active material was made lower than that of the conventional product A by about 15%.

FIG. 1 compares the viscosities of the pastes used in the conventional products A and B and the paste used in the product of the present invention. In FIG. 1, the viscosities of the pastes of the conventional product A are set to 100%. The ratio is shown as a percentage. In order to improve the filling property of the paste, it is necessary to use a paste having a viscosity in the range shown by the diagonal lines in FIG.

As is clear from FIG. 1, the viscosity of the paste used in the product of the present invention is about 40% higher than the viscosity of the paste used in the conventional product B, and is about the same as the viscosity of the paste used in the conventional product A. is there. Therefore, the product of the present invention can obtain the same good filling property as that of the conventional product A.

The total pore volume (porosity) of the anode active material used in the product of the present invention is 0.172 CC / g, and the pore volume of the micropores having a diameter of 0.072 CC / g.
The macropore volume of 18CC / g and the diameter of 0.2-4μm is
It was 0.149 CC / g.

The results of the tests conducted on the conventional product and the product of the present invention are shown below. The batteries used in all the tests are single-cell batteries having the same volume and the same electrode group structure (one anode, one cathode). .

Fig. 2 shows the results of the life test conducted on the conventional product and the product of the present invention. In this life test, the discharge current was 1A.
Then, the battery was discharged to a final voltage of 1.70V, and a constant voltage charge was performed for 4 hours at a charging voltage of 2.45V (limit current 1A).

From FIG. 2, the initial capacity of the product of the present invention is 32 than that of the conventional product A.
%, Which is 13% higher than that of the conventional product B. Further, it can be seen that the life of the product of the present invention is increased by about 100% as compared with the conventional product A and is increased by about 150% as compared with the conventional product B.

FIG. 3 shows the total pore volume of the paste used in the product of the present invention,
The total pore volume of the pastes used in the conventional products A and B are shown for comparison. In the conventional product A, the total pore volume is small because the paste density is high, but in the conventional product B and the product of the present invention, the total pore volume is 0.169 CC / g and 0.172 CC / g, respectively, which is larger than that of the conventional product A.

As shown in FIG. 9, if the total pore volume is less than 0.16 CC / g, the pore volume of either macropores or micropores will be small and the capacity will be poor. The discharge conditions in the measurement of FIG. 9 are the same as those in the test of FIG.

Further, as shown in FIG. 10, the total pore volume of the anode active material is
When it exceeds 0.18 CC / g, the adhesion of the whole active material is impaired,
The life is shortened. The charging / discharging conditions in the measurement of FIG. 10 are the same as those in the test of FIG.

From the above, the total pore volume of the anode active material was 0.16 to 0.18.
It is necessary to select in the range of cc / g.

FIG. 4 shows a comparison of the pore volume of pores of less than 0.2 μm for the anode active materials of the present invention of the anode active materials of the conventional products A and B. 0.2 μm for conventional product A
Pore volume of less than 0.023 CC / g, conventional product B has the same pore volume of 0.042 CC / g, both of which are more than 0.02 CC / g, but the pore volume of the positive electrode active material of the present invention is less than 0.2 μm. Is as low as 0.018 CC / g.

Fig. 5 shows the active material utilization rate when the volume of pores of 0.2 to 4 µm is 0.13 CC / g (constant) and the volume of pores of less than 0.2 µ0m is variously changed. The discharge current was set to 1 A, and the discharge was stopped after 120 minutes. At that time, the total anode active material utilization rate was 28%. The pore volume of the micropore is
When it is 0.02CC / g or less, there is almost no difference in the utilization factor of the active material on the surface and the inside, but the pore volume of the micropore is 0.02CC.
When it exceeds / g, the difference becomes extremely wide. Therefore, in the present invention, the pore volume of the micropores of the anode active material is 0.02.
cc / g or less

FIG. 6 shows that the diameters of the conventional products A and B and the product of the present invention are 0.2
It is shown by comparing the volumes of the pores in the range of ˜4 μm. From FIG. 6, 0.2-4 μm pore volume of the conventional product A is 0.107, and 0.2-4 μm pore volume of the conventional product B is 0.166 CC /
However, in the product of the present invention, it is as high as 0.149 CC / g.

FIG. 7 shows the active material utilization rate with respect to the pore volume of macropores of 0.2 to 4 μm when the pore volume of micropores is 0.02 cc / g (constant). In this test, discharge was performed at a discharge current of 1 A, and the discharge was stopped after 120 minutes. In this case, the utilization rate of all positive electrode active materials was 28%. 0.2 ~ 4
If the pore volume of the micropores of μm is 0.13 cc / g or more, there is almost no difference in the active material utilization rate between the surface and the inside of the electrode plate, but if the pore volume of the macropores is below 0.13 cc / g, the electrode plate The difference between the active material utilization rates on the surface and inside increases. Therefore, in the present invention, the pore volume of the macropores of 0.2 to 4 μm is 0.13 cc / g or more.

[Effects of the Invention] As described above, according to the present invention, the pore volume of the micropores can be made small and the pore volume of the macropores can be made large, so that the liquid diffusion into the electrode plate during the discharge reaction can be prevented. It can be performed smoothly and the active material on the surface and inside of the electrode plate can be used uniformly. In addition, if the total active material utilization rate is the same, the utilization rate of each PbO _{2 base} particle will be lower than before, so the volume change of the active material due to repeated charging and discharging will be reduced to delay mud formation and increase the service life. It can be extended.

Further, according to the present invention, since lead oxide having a small particle size is used as a raw material, it is possible to maintain the paste viscosity at the same level as the conventional one even if the paste density is lowered, and sufficiently increase the porosity. As a result, the capacity can be increased.

[Brief description of drawings]

FIG. 1 is a graph showing paste viscosity ratios of a conventional product and the present invention product, and FIG. 2 is a diagram showing comparison of cycle life test results of the conventional product and the present invention product, and FIG.
FIG. 4 is a graph showing a comparison of the total pore volumes of the anode active material of the conventional product and the present invention product, and FIG. 4 is a comparison of the micropore pore volumes of the anode active material used in the conventional product and the present invention product. The graph shown in FIG. 5 is a diagram showing the relationship between the pore volume of the micropores and the utilization rate of the active material, and FIG. 6 compares the pore volume of the macropores of the anode active material for the conventional product and the product of the present invention. FIG. 7 is a graph showing the relationship between the pore volume of the macropores of the anode active material and the utilization rate of the active material, and FIG. 8 is a graph showing the pore distribution of the anode active material. FIG. 9 is a diagram showing the relationship between the total pore volume of the anode active material and the capacity ratio, and FIG. 10 is a diagram showing the relationship between the total pore volume of the anode active material and the cycle life.

Claims (1)

(57) [Claims] 1. The total pore volume is 0.16 to 0.18 cc / g and the diameter is 0.2.
Volume of pores less than μm is 0.02cc / g or less, diameter 0.2-4.0μ
A lead-acid battery characterized by using an anode plate provided with an anode active material having a pore volume of m of 0.13 cc / g or more.