JPS59184453A - Lead storage battery - Google Patents

Abstract

PURPOSE:To increase the life of a lead storage battery by coating the surface of an electrode plate with a solid mixture consisting of an epoxy resin and the oxide of an acid-proof electrochemically-inactive metal. CONSTITUTION:The surface of an electrode plate is coated with a solid mixture consisting of an epoxy resin and the oxide of a metal such as Al, Ca, Si, Zr or Y. The mixture consisting of the oxide and the epoxy resin can effectively be formed over the electrode by applying or spraying a mixture paste, prepared by using water instead of an organic solvent as a solvent for duluting or fluidizing the oxide and the epoxy resin, over the surface of an unformed plate for a lead storage battery before the paste is dried and solidified. in the thus formed electrode plate, highly porous oxide particles exist in the epoxy resin rendering the mixture itself highly porous. As a result, diffusion of sulfuric acid is not retarded and there is no possibility that capacity reduction might be caused.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lead-acid battery used in a wide range of applications such as automobile SLI, stationary power supply, and mobile power supply.

Conventional configurations and their problems Despite their long history, lead-acid batteries have several problems that have not yet been resolved. One of these is the phenomenon of fineness of the positive electrode active material during charge/discharge cycles and the resulting softening and shedding of the active material layer. This phenomenon occurs not only in the paste type, but also in the clad type, which is surrounded by a porous body of resin or glass, and the bonding force between active material particles weakens due to miniaturization, resulting in a decrease in capacity and voltage characteristics. . Furthermore, particles that have lost their binding strength fall off and accumulate at the bottom, creating a risk of short circuits at various locations.

In order to improve the life characteristics, one thing is essentially to prevent the miniaturization of the active material.
Alternatively, even if it is not possible to prevent the crystals from becoming fine, it is desirable to have a structure in which at least one particle does not separate from the electrode plate even if the crystals become fine. Bondage has a good effect, but in reality, there is a limit to the strength of the battery case, and it cannot be used sufficiently.

As a solution to the above problem, the present inventors have already integrated a rigid layer on the surface of the electrode by applying a paste of oxides of metals such as A#+ Ca, Si, and Zr to the electrode plate. proposed an electrode configuration that

This rigid layer can prevent active material particles from falling off from the electrode plate.

However, although the oxide constituting the above-mentioned rigid layer is preferable because it is hard and acid-resistant, the bond strength itself is not necessarily strong. Therefore, large cracks may occur in such an oxide layer. A gap is formed between the electrode plate surface and the oxide layer, and when the oxide is applied and fi' is reduced, the oxide may eventually separate from the electrode surface.

Therefore, in order to improve the mechanical strength of the oxide layer, it is better to make the oxide layer have a very dense structure, but in that case, the diffusion of sulfuric acid to the electrode surface during discharge is significantly inhibited. The discharge capacity of the battery decreases.

Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems and extend the life of a lead-acid battery. ・Structure of the Invention The lead-acid battery of the present invention is substantially acid-resistant and electrochemically resistant. oxides that are inactive, especially Si, Aβ, Ca and Zr.

It is characterized by comprising an electrode plate whose surface is coated with a solid mixture of a metal oxide such as Y and an epoxy resin, and the entire electrode plate group may be coated with the solid substance. In order to improve the drawbacks of the oxide layer, the invention includes:
It is characterized by the use of a mixture of metal oxides such as 3i, A, and 5 and epoxy resin. Epoxy resin has much stronger adhesion to oxides than fluororesin or silicone resin. Therefore, the bond between the epoxy resin and the oxide is improved by 4 feet, which sufficiently compensates for the weak bond between the oxides and forms a porous layer, which is better than the oxide alone or the epoxy resin alone. Its strength will be much stronger. Furthermore, if these mixtures are present on the surface of the electrode plate or in the electrode plate group before the epoxy resin in the mixture dries and solidifies, the epoxy resin formed on the surface and the electrode plate in the process of drying and solidifying the epoxy resin. The bond between them will be very strong.

Therefore, a lead-acid battery electrode plate having the structure of the present invention can sufficiently withstand deformation of the electrode plate due to long-term charge/discharge cycles.

Additionally, it is possible to consider a technique in which thermoplastic resin gold is used as the resin, mixed with the above oxide particles, and applied to the electrode plate surface, but the bonding force with the electrode plate surface is due to the mixture of epoxy resin and oxide. It doesn't come close to things.

Furthermore, when the electrode is coated only with epoxy resin, the dense structure of the epoxy resin prevents the diffusion of sulfuric acid during the discharge reaction, resulting in a decrease in capacity.

In the present invention, since highly porous oxide particles are present in the epoxy resin, the mixture itself also becomes highly porous. Therefore, in the discharge.

The diffusion of sulfuric acid is less likely to be impeded and the capacity loss is less - On the other hand, a method for forming a mixture of oxide and epoxy resin on an electrode is to use an organic solvent as a solvent to dilute or fluidize the oxide and epoxy resin. An effective method is to apply or spray a mixed paste using water instead of a solvent onto the surface of an unformed lead-acid battery plate, and then dry and solidify the paste.

DESCRIPTION OF EXAMPLES Regarding the manufacture of an electrode plate, first, a mixture of alumina, aqueous epoxy resin, and water was coated on both sides of an unformed positive electrode plate having a size of 14×11 cm. however.

The water contained 5% by weight monobasic aluminum phosphate as a binder for alumina. after that.

The above mixture was dried and solidified. A battery was produced by chemically charging a combination of four unformed positive electrode plates and five unformed negative electrode plates.

However, a factory item was used for the negative electrode plate.

The weight ratio of alumina, aqueous epoxy resin, and water in the mixture applied to the positive electrode plate is shown in the following table.

In addition, a battery using a positive electrode plate without a coating layer formed on the surface of the electrode plate is used. In order to reduce the battery engineering time to 3 hours, a polyethylene porous sheet was used as a separator, but a glass mat was not used.

The initial capacity and life characteristics of these batteries when discharged at a current of 10 A were investigated. Life test.

Discharging 100% at a constant current of 10A and charging at 100% of the previous discharge amount at 8A were repeated.

Figure 1 shows the initial capacities of batteries A through B. From Figure 1,
Although the initial capacity of Battery H whose electrode surface was coated only with epoxy resin was significantly reduced, the initial capacity of the other batteries was only slightly reduced.

FIG. 2 shows the change in discharge capacity of batteries A, C, F, H, and ■ during charge/discharge cycles. Other batteries have better life characteristics than battery engineered batteries.

It can be seen that the life characteristics of batteries C and F that utilize the present invention are particularly excellent.

FIG. 3 VC shows the number of life test cycles until 60% of the initial capacity was reached in the life test for batteries 1 to 5. It can be seen that batteries B to G utilizing the present invention have better life characteristics than other batteries.

As described above, it is clear from the above results that the lead-acid battery to which the present invention is applied has excellent life characteristics and its initial capacity does not decrease. In other words, it is presumed that the mixed solid of epoxy resin and alumina has strong mechanical strength and is highly porous.

In the examples, alumina was used as the oxide material, but oxides of St, Ca, Zr, and Y may also be used.
The battery characteristics were similar to those of the example.

Effects of the Invention As described above, according to the present invention, the life characteristics can be improved without reducing the initial capacity, and it is suitable for applications that require a long life such as electric vehicles and forklifts that will be developed in the future. This is a major contribution to the expansion of lead-acid batteries.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the initial capacity of batteries using various positive electrode plates.
FIG. 2 is a diagram showing changes in discharge capacity during charge/discharge cycles, and FIG. 3 is a diagram showing the number of life test cycles.

Claims (1)

[Claims] A lead-acid battery comprising an electrode plate whose surface is coated with a solid mixture of acid-resistant and electrochemically inert oxide and epoxy resin.