JPS6231951A - Alkaline battery - Google Patents

Abstract

PURPOSE:To increase high rate discharge performance without a decrease in filling accuracy by mixing flat-shaped zinc powder with spherical zinc particles containing a specified amount of particles whose ratio of the minor axis to the major axis is in a specified range, and using the mixture as a negative active material. CONSTITUTION:Flat-shaped zinc powder is mixed with spherical zinc particles containing 90% or more of zinc particles whose ratio of the minor axis to the major axis is 1.0-1.5, and the mixture is used as a negative active material. To increase filling accuracy, particle size of zinc particles whose content is 90% or more is limited to 48-40 mesh. The flat-shaped zinc powder whose particle surface is flat or zinc foil is used so that smooth surface contact with spherical zinc particles is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alkaline battery that can improve heavy load discharge characteristics without reducing the filling accuracy of negative electrode material.

[Conventional technology]

Conventionally, in alkaline batteries using a gelled zinc cathode active material in which zinc particles and an alkaline electrolyte are mixed, irregular and elongated zinc particles have been used to increase the discharge reaction surface area per unit weight.

As shown in FIG. 3, the zinc particles used in this ζ have an elongated shape in which the ratio (//w) of the short axis diameter W and the long axis diameter J of the particles is 1.8 or more. Specifically, the particle size is 48-20
Most of them have 0 mesh, and 90 of them have long sleeve diameter/short axis diameter ratio (J/vJ) of 1.9 to 2.5.

These zinc particles are converted into carboxymethylcellulose (aMO)
A predetermined amount of the mixed powder is weighed out and filled into a cathode container, and then an alkaline electrolyte is poured into the zinc negative electrode active material. was making.

However, the ratio of major axis diameter/minor axis diameter (J/lt) is 1
．． When zinc particles with a size of 8 to 2.5 are used, it is difficult to accurately fill the negative electrode container with a predetermined amount of zinc particles, and as alkaline batteries become smaller and the amount of active material decreases, the amount of zinc particles filled becomes more uneven. A problem arises in which the size becomes large.

As described above, when variations occur in the amount of zinc particles filled, it becomes difficult to maintain a balance between the capacitance of the positive electrode and the capacitance of the negative electrode. That is, if there are too many zinc particles, the positive electrode will completely react while the negative electrode still remains, and hydrogen gas will be generated from the positive electrode, causing the battery to swell and leak.

Furthermore, if the amount of zinc particles is too small, the discharge capacity of the battery will decrease.

From the above, in alkaline batteries, it is necessary to make the electric capacity of the negative electrode slightly smaller than the electrode capacity of the positive electrode, so that a small amount of the positive electrode remains after all the negative electrode has reacted. In No. 117869/1986, the ratio of the major axis diameter/minor axis diameter (j/w') of zinc particles is 1, as shown in Figure 4.
．． By using zinc particles in which 90% or more of the particles fall within the range of 0 to 1.5, the filling accuracy of the negative electrode is improved, and an attempt is made to obtain a battery with small variations in discharge capacity.

As a result, it was possible to suppress the variation rate in filling accuracy to 4% or less, which was a significant effect compared to the conventional variation rate of 63-9.6 inches. Furthermore, if the particle size of the zinc particles that account for 90% or more is set to 48-80 mesh, it is possible to suppress the variation rate to 3 inches or less and improve the weighing accuracy.

As a result, the filling accuracy of the negative electrode of the small alkaline battery becomes extremely high, and the dispersion in the discharge capacity can be reduced, so that the discharge performance can be improved.

[Problem that the invention seeks to solve]

By using zinc particles that account for 90 or more particles with a ratio of major axis diameter/minor axis diameter in the range of 1.0 to 1.5, it is possible to improve the filling accuracy of the negative electrode, but the discharge performance When a large current is applied to the batteries, they cannot be sharpened, resulting in a problem that their heavy load characteristics are inferior to those of alkaline batteries constructed using zinc particles with a ratio of long sleeve diameter/short shaft diameter of 1.9 to 2.5. .

The invention was made by paying attention to such problems, and provides spherical zinc particles having 90 or more particles having a ratio of major axis diameter/minor axis diameter within the range i of 1.0 to 1.5. The object of the present invention is to provide an alkaline battery with excellent heavy load discharge characteristics without reducing filling accuracy by adding flat zinc to the negative electrode agent.

[Means for solving problems]

This invention provides zinc particles having 90% or more of spherical zinc particles having a ratio of major axis diameter/minor axis diameter within the range of 1.0 to 1.5.
The negative electrode material is made by adding flat zinc.

In order to improve the filling accuracy, it is necessary to set the particle size of the zinc particles occupying 90 ts or more to 48 to 80 mesh.

Further, some examples of flat zinc include those having a shape that allows smooth surface contact with spherical zinc particles, and specifically, zinc particles or zinc foil having at least a portion of the surface in a flat shape. In this flat zinc, the surface area of the flat portion must be 20 squares or more relative to the total surface area, and especially when the surface area is 50 squares or more, the effect becomes more noticeable. In this case, the amount of flat zinc added is preferably 5 to 50% by weight based on the total weight of negative electrode zinc.

[For production]

In the present invention, the shapes of the spherical zinc particles can be made to be approximately the same by setting the ratio of the major axis diameter to the minor axis diameter of the spherical zinc particles having 90 or more squares to 1.0 to 1.5.

By containing 9096 or more of such spherical zinc particles, it is possible to accurately weigh the zinc particles, and it is possible to improve the filling accuracy of the negative electrode material.

In addition, when flat zinc is added to this, it is well dispersed between spherical zinc particles, and as a result, the conventional zinc particles (particle size 32 to 100 mesh, ratio of major axis diameter / minor axis diameter) (1.9 to 2.5 is 90% or more), the filling accuracy is higher than that of 1.9 to 2.5 (90% or more).

Furthermore, 48 to 80 spherical zinc particles occupying 90q6 or more
By using a mesh particle size, particles of a more or less uniform size can be obtained, so that the filling accuracy can be further improved.

On the other hand, by adding flat zinc to spherical zinc particles, the surface area for the discharge reaction of zinc particles, which occurs when only spherical zinc particles are used, is reduced, and the number of mutual contact points between zinc particles is reduced. Deterioration of conductivity can be prevented. This is thought to be because the addition of flat zinc improves the surface contact between the zinc particles9, increasing the electronic conductivity and discharge reaction surface area between the zinc particles.

〔Example〕

A first embodiment of this invention will be described below with reference to the drawings.

Figure 1 shows that this invention is compact and has excellent heavy load characteristics.
This is applied to RO3 alkaline manganese batteries. In the figure, 1 is an iron container whose entire surface is nickel-plated and also serves as a positive terminal. 2 is a positive electrode mixture prepared by adding graphite as a conductive agent to manganese dioxide and press-molding the mixture. 3 is a gelled negative electrode material which is disposed on the positive electrode mixture 2 with a separator 4 interposed therebetween and is made by dispersing the zinc particles of the present invention together with a gelling agent in an alkaline electrolytic solution in which zinc oxide is dissolved. 5 is a negative electrode current collector made of brass, and 6 is a negative electrode metal terminal plate that is in contact with the negative electrode current collector 5. Reference numeral 7 denotes an insulating backing, which insulates between the iron container 1 and the negative electrode metal terminal 6, and also seals the gap therebetween.

The above-mentioned gelled negative electrode material 3 is a spherical zinc particle having a particle size of 48-80 mesh and having 9096 or more particles with a ratio of the major axis diameter/minor axis diameter of the particles in the range of 1.0 to 1.5. 5 to 50% by weight of flat zinc is added to the total weight of the negative electrode zinc.

It is desired that the surface area of the flat portion of the flat zinc used for this purpose is 20 inches or more of the total surface area. This flat zinc is manufactured as follows.

The first method is to prepare spherical or teardrop-shaped atomized zinc particles with a predetermined particle size by a gas atomization method, and then roll them through a roller press machine. As shown in FIG. 2(a), flat zinc deformed into a flat shape is obtained.

As a second method, flat zinc can be obtained by spraying molten droplets onto a smooth plate surface or the like during melt spraying, and deforming the portion in contact with the plate surface into a flat shape.

The third method is to pour molten zinc onto a smooth plate or rotating drum, form the thin zinc into a plate or zinc foil using means such as rolling, and then cut this into fine pieces to create the shape shown in Figure 2 (6). Flat zinc as shown is obtained.

By the way, the LRO3 alkaline manganese power supply was filled with a negative electrode material containing 90 or more zinc particles with a particle size of 32 to 100 metric and a ratio of major axis diameter/minor axis diameter of 1.8 to 2.8. And the particle size is 48 to 80 mesh.

The flat zinc particles produced by the method of gt containing 90% or more of spherical zinc particles with a ratio of major axis diameter/minor axis diameter within the range of 1.0 to 1.5 are 20% of the weight of the entire negative electrode zinc. Inventive product B, in which an LRO3 alkaline manganese battery was filled with a negative electrode agent containing 909% by weight, and the same spherical zinc particles as inventive product B,
An LRO3 alkaline manganese battery was filled with a negative electrode agent containing 20% by weight of flat zinc obtained by cutting a 100 μm zinc foil produced by the third method into 0.3n square pieces, based on the total weight of the negative electrode zinc. We made 100 prototypes of each of the invention products C and the filling average weight (X), the variation (3σ
), and the filling amount variation rate (3σ/X) Xioo were investigated, and the results shown in Table 1 were obtained.

Table 1 According to this table, it can be seen that the variation in filling amount and rate are smaller compared to product B of the present invention and conventional product A.

Next, inventive products B and O and a negative electrode material containing 9096 or more spherical zinc particles having a particle size of 48 to 80 mesh and a ratio of major axis diameter/minor axis diameter within the range of 1.0 to 1.5 were added to LRO3. We prototyped 50 of each of the conventional products filled with alkaline manganese batteries, and first examined the closed circuit voltage and short circuit current with a resistance of 50 at 20°C, and also examined the discharge duration with a constant resistance of 5 Ω. The results shown in the table were obtained.

Table 2 According to this table, it was found that products B and O of the present invention were able to generate a larger short circuit current than the conventional products and had excellent heavy load discharge characteristics.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

〔Effect of the invention〕

According to this invention, the ratio of major axis diameter/minor axis diameter is 1.0 to 1.5.
By adding flat zinc to spherical zinc particles having particles in the range of 90 or more to form the negative electrode material, it is possible to reduce the variation in filling amount, and also to generate a large short circuit current and to have heavy load characteristics. It is possible to obtain an excellent alkaline battery. In particular, in small and thin batteries, the accuracy of weighing the negative electrode material is increased, so the capacitance of the positive electrode and the negative electrode can be balanced and the discharge characteristics of the battery can be made uniform.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing one embodiment of the present invention, Figure 2 (a)
, (b) are enlarged views showing different flat zinc particles used in the same example, Fig. 3 is an enlarged view showing typical shapes of zinc particles used in conventional alkaline batteries, and Fig. 4 is an enlarged view of the conventional and FIG. 2 is an enlarged view showing a typical shape of spherical zinc particles used in the alkaline battery of the present invention. 1... Iron container 2... Positive electrode mixture 3... Gel-like negative electrode agent 4... Separator 5... Negative electrode current collector 6... Negative electrode metal terminal plate 7... Insulating backing first Figure 2 (a) (b) Figure 3 Figure 4

Claims (3)

[Claims] (1) A negative electrode material is formed by adding flat zinc to spherical zinc particles having 90% or more of particles having a ratio of major axis diameter/minor axis diameter in the range of 1.0 to 1.5. alkaline battery. (2) The alkaline battery according to claim 1, wherein 90% or more of the spherical zinc particles have a particle size of 48 to 80 mesh. (3) Flat zinc is 5% of the weight of the entire negative electrode zinc particle.
The alkaline battery according to claim 1, characterized in that the content is 50% by weight.