JPH10270017A - Non-aqueous electrolytic battery positive pole plate and non-aqueous electrolytic battery therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolytic battery pole plate without any drop in energy density and capable of improving high rate discharging characteristics by providing nickel oxy-hydroxide including particles composed with the surface mainly consisting of curved surfaces in such a configuration of a spherical shape and/or approximating a spherical shape. SOLUTION: A pole plate and a battery excellent in high energy density and changing/discharging cycle characteristics are obtained by providing nickel oxy- hydroxide mainly including particles in configuration of spherical and/or approximating the spherical shape and its surface is mainly composed of curved surfaces. Furthermore, by setting the average particle diameter of the nickel oxy-hydroxide in a range from 1 to 100 μ, a pole plate excellent in balance between high rate discharging characteristics and an energy density is obtained. In addition, when the nickel oxy- hydroxide is made a positive pole plate, which forces being held by a conductive porous body in the ternary structure, the energy density of the pole plate is enhanced furthermore. When the nickel hydroxide is formed in a spherical shape or in a shape approximating the spherical shape, increase in specific area corresponding to a decrease in the particle diameter is suppressed so as to increase the energy density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery and a positive electrode plate thereof.

[0002]

2. Description of the Related Art Particles of a positive electrode active material, nickel hydroxide, are directly applied together with a binder to an active material support such as a nickel mesh or a sponge-like porous nickel having a three-dimensionally continuous structure. The positive electrode plate for an alkaline battery can achieve a high capacity and has a very simple manufacturing method, is capable of a continuous process, and is economically advantageous. In this case, the energy density of the positive electrode plate varies greatly depending on the shape and size of the particles of the nickel hydroxide powder used.

According to JP-A-60-131765, the energy density is improved by filling a nickel hydroxide powder having a spherical or nearly spherical particle shape into an active material support such as a sponge-like nickel porous body. It is stated that a positive electrode plate for an alkaline battery can be obtained. In order to easily fill the sponge-like nickel porous body with the paste-like active material, it is desirable that the active material particles used are somewhat smaller.The smaller the particle size of the active material is compared to the pore size of the porous body, the more the porous material skeleton It is considered that the paste is easily filled because the resisting force is small.

However, as the particle size of the active material decreases, the specific surface area increases, and the amount of liquid adsorbed on the particle surface increases. Therefore, in order to obtain a paste having the same viscosity, the smaller the particle size, the smaller the particle size. Requires a lot of liquid,
The content of the active material particles in the paste will decrease.

[0005] Therefore, even if the paste is easily filled in the porous body, the actual energy density is not improved. Here, by forming the nickel hydroxide particles into a spherical or spherical shape, it is possible to suppress an increase in the specific surface area due to a decrease in the particle diameter, and to provide a positive electrode plate for an alkaline battery with improved energy density. I can do that.

On the other hand, in a non-aqueous electrolyte battery such as a lithium battery, a metal foil such as aluminum or copper is used as a current collector, and an active material is suitably used together with a conductive additive such as acetylene black and a binder such as a fluorine-containing polymer. Generally, an electrode is produced by forming a paste using a suitable solvent and applying the mixture on a current collector.

Since the ionic conductivity of the non-aqueous electrolyte is inferior to that of the aqueous electrolyte, the thickness of the active material mixture layer of the electrode plate is usually several tens to improve the high rate discharge characteristics.
A method of making it as thin as 100 μm is used. However, as the active material mixture layer becomes thinner, the amount of the current collector with respect to a certain amount of the battery active material increases, and as a result, the relative amount of the active material in the entire battery decreases, so that the energy density of the battery decreases. I will be forced.

[0008]

As described above, in a non-aqueous electrolyte battery such as a lithium battery, the thickness of the active material mixture layer of the electrode plate is set to several tens in order to improve high rate discharge characteristics.
In many cases, a very thin method of 0 to 100 μm is used. However, as the active material mixture layer becomes thinner, the amount of the current collector with respect to a certain amount of the battery active material increases, and as a result, the relative amount of the active material in the entire battery decreases, so that the energy density of the battery decreases. Invite. Accordingly, there is a need for a non-aqueous electrolyte battery electrode plate that improves high-rate discharge characteristics without lowering the energy density.

[0009]

The present invention has been made to improve the energy density of a positive electrode plate for a non-aqueous electrolyte battery by eliminating such disadvantages. And / or and a nickel oxyhydroxide having a shape similar to a sphere and having a surface mainly composed of a curved surface, and more preferably nickel oxyhydroxide. Has an average particle diameter of 1 to 100 μm. In addition, the present invention is characterized in that nickel oxyhydroxide is held in a conductive porous body having a three-dimensional structure. Further, a non-aqueous electrolyte battery provided with these electrode plates is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention aims at providing a positive electrode plate having an extremely high energy density and a nonaqueous electrolyte battery provided with the same, and has a spherical shape and / or a shape approximate to a spherical shape, the surface of which is spherical. A nickel oxyhydroxide mainly containing particles mainly composed of a curved surface is provided. The shape approximate to a sphere here means a shape close to a sphere, a chicken egg, a substantially chicken egg, a rugby ball, and a substantially rugby ball.

Thus, it is possible to provide an electrode plate and a battery having high energy density, high rate discharge characteristics, and excellent charge / discharge cycle characteristics. At this time, by using nickel oxyhydroxide containing cobalt, the cycle characteristics can be made good and the discharge characteristics can be made very uniform.

Further, when the average particle size of the nickel oxyhydroxide is selected in the range of 1 to 100 μm, it is possible to obtain an electrode plate having a more excellent balance between high-rate discharge characteristics and energy density.

[0013] In addition, the energy density of the electrode plate can be further increased by forming the positive electrode plate in which nickel oxyhydroxide is held in a conductive porous body having a three-dimensional structure.

In the present invention, the active material includes a host material capable of inserting and extracting lithium ions.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

The positive electrode plate according to the present invention was manufactured as follows.

First, a mixed powder of 80 parts of a nickel oxyhydroxide powder having a spherical shape and a particle shape similar thereto, 10 parts of a carbonyl nickel powder, and 10 parts of a cobalt powder obtained by hydrogenating cobalt oxalate was mixed with an aqueous solution of carboxymethyl cellulose. The paste was filled into a sponge-like nickel porous body having an average pore diameter of 0.3 mm, a porosity of 96%, and a thickness of 1.7 mm, and dried at 80 ° C. for 1 hour. Next, it is immersed in a fluororesin dispersion liquid,
After drying at 0 ° C. for 1 hour, it was pressed at a pressure of 500 kg / cm 2 to obtain a positive electrode plate A according to the present invention.

Here, the nickel oxyhydroxide powder having a spherical shape or a particle shape similar thereto was prepared by, for example, chemical oxidation of the nickel hydroxide powder in an aqueous alkaline solution. For example, when nickel hydroxide used as a raw material is produced by a neutralization reaction, fine nickel hydroxide particles serving as nuclei are dispersed and the reaction is allowed to proceed gradually. Then, a uniform crystal grows around the nucleus, and the particle shape becomes nickel hydroxide having a spherical shape and / or a shape similar thereto, and the particle shape of the obtained nickel oxyhydroxide also has a spherical shape and / or a shape similar thereto. be able to.

FIG. 5 (a) is an explanatory view showing the particle shape of the nickel oxyhydroxide according to the present invention when observed by SEM at a magnification of 500. FIG. 5 (b) shows particles observed by SEM at 500 times magnification of nickel oxyhydroxide produced by chemically oxidizing a normal nickel hydroxide powder whose particle surface is not mainly composed of a curved surface. It is explanatory drawing which shows a shape.

Next, nickel hydroxide powder having a spherical shape and a particle shape similar thereto, 5 wt% of acetylene black as a conductive material, 5 wt% of polyvinylidene difluoride and 3 wt% of n-methyl-2-pyrrolidole as a binder Was mixed in a dry room to form a paste, and then applied and dried on a stainless steel foil of a current collector to obtain a positive electrode plate A ′ according to the present invention.

Further, the surface of the particles is not mainly composed of a curved surface, a normal nickel hydroxide powder, 5 wt% of acetylene black as a conductive material, 5 wt% of polyvinylidene difluoride as a binder and n-methyl-2-vinyl A mixed solution with 3 wt% of pyrrolidol was mixed in a dry room to form a paste, which was then applied to a stainless steel foil of a current collector and dried to obtain a conventional positive electrode plate B ′.

Further, a conventional positive electrode plate B was obtained in the same manner as the positive electrode plate A, except that a normal nickel hydroxide powder whose particle surface was not mainly composed of a curved surface was used.

In each of the positive plates A, A ', B and B', two lithium metal plates having the same size as the counter electrode, ethylene carbonate and diethyl carbonate containing 1 M lithium perchlorate in the electrolyte were used. A test battery was manufactured using a mixed solvent of 100 ml with the above.

For the measurement of the potential of the positive electrode, a metallic lithium reference electrode was used. These batteries were subjected to constant current discharge at 25 ° C. at various current densities to 1.5 V.

The average particle size of the nickel oxyhydroxide powder used for producing the positive plates A and B is 1 μm to 12 μm.
FIG. 1 shows a change in the amount of kneading liquid necessary to obtain a paste having a viscosity suitable for filling when the thickness is changed to 0 μm.

FIG. 1 shows that the positive electrode plate according to the present invention requires a smaller amount of kneading liquid than the conventional method. This is considered to be due to the fact that the specific surface area is extremely small because the particle shape is spherical or similar.

The change in the energy density obtained from the filling amount when the average particle size of the nickel oxyhydroxide powder used for producing the positive plates A, A ′, B and B ′ was changed from 1 μm to 120 μm. It is shown in FIG.

FIG. 2 shows that the energy density is significantly improved over that of the conventional method. Especially when the particle size is small, the difference from the conventional method is large. The reason is considered as follows.

That is, when nickel oxyhydroxide powder having an average particle diameter of about 100 μm is used, the paste cannot be sufficiently filled in the porous body because the particles are large. When the conventional nickel oxyhydroxide powder is used, when the particle diameter is reduced to about 70 μm, the paste or filling becomes easy, so that the energy density is slightly improved, but when the particle diameter is further reduced, the specific surface area of the particles increases. As a result, the amount of the kneading liquid increases, so that the energy density significantly decreases.

On the other hand, when a nickel oxyhydroxide powder having a spherical shape and a particle shape similar thereto is used as in the present invention, the specific surface area is extremely small even if the particle size is reduced to about 1 to 70 μm. Since the amount of the kneading liquid increases due to the decrease in the particle diameter, the effect of increasing the paste filling due to the ease of filling the paste is larger than the decrease in the content of the active material particles, and the energy density is reduced. It is thought to improve. At this time, when the nickel hydroxide powder is held on the conductive porous body having a three-dimensional structure such as the sponge-like nickel porous body used in A, the paste is compared with A ′ obtained by applying the paste on the current collector. It can be seen that the energy density is further improved.

Next, for the positive electrodes A, A 'and B' using nickel oxyhydroxide particles having an average particle diameter of 70 μm, the change in the energy density of the electrodes when the discharge current density is changed is shown in FIG. .

FIG. 3 shows that the positive electrode plate according to the present invention has a higher energy density because the volume ratio of the active material in the electrode plate is higher than that of the conventional method.

It was also confirmed that the dependency of the energy density of the electrode plate on the discharge current density, that is, the high-rate discharge characteristics was at the same level as that of the conventional method.

As described with reference to FIG. 2, also in this case, the positive electrode plate A in which nickel hydroxide powder is held on a conductive porous body having a three-dimensional structure, such as a sponge-like nickel porous body. It is confirmed that the energy density and the high-rate discharge characteristics are further improved as compared with A ′ obtained by applying the paste on the current collector.

FIG. 4 shows the change in the discharge capacity retention rate of the positive plates A and A 'according to the present invention and the positive plate B' according to the conventional method as the charge / discharge cycle progresses.

FIG. 4 shows that the positive electrode plates A and A 'according to the present invention have better charge / discharge cycle characteristics than the positive electrode plate B' according to the conventional method. This is because the particle shape of the nickel hydroxide used for the positive electrode plate according to the present invention has a spherical shape and a shape close to a spherical shape, and since the crystal growth direction is diverse, the volume expansion and contraction of the active material due to charging and discharging is caused. It is considered that this is because the action of (1) can be dispersed in all directions. This makes it possible to suppress the pulverization of the active material, which is one of the causes of cycle deterioration, and is considered to have contributed to the improvement of charge / discharge cycle characteristics.

On the other hand, the nickel hydroxide powder used for the positive electrode plate B 'according to the conventional method has a shape in which crystals grow in a specific direction, and the effect of volume expansion and contraction of the active material due to charge and discharge is reduced only in the specific direction. I will receive it in a concentrated manner. As a result, the active material is liable to be pulverized, and it is considered that the discharge capacity is more greatly reduced as the charge / discharge cycle proceeds.

In fact, when the test electrode was disassembled after 500 cycles, pulverization of the active material was confirmed in the positive electrode plate B ', but the active materials in the positive electrode plates A and A' were particles at the start of the cycle test. The shape was maintained. In this case, also in this case, the positive electrode plate A in which the nickel hydroxide powder is held in a conductive porous body having a three-dimensional structure such as a sponge-like nickel porous body applies the paste on the current collector. A '
The charge / discharge cycle characteristics are further improved as compared with the above.

[0039]

The positive electrode plate for a non-aqueous electrolyte battery according to the present invention is a nickel oxyhydroxide having a spherical shape and / or a shape close to a spherical shape, the surface of which mainly contains particles mainly composed of curved surfaces. It is characterized by having.
This makes it possible to provide an electrode plate having a high energy density and excellent high-rate discharge characteristics and charge-discharge cycle characteristics.

At this time, by using nickel oxyhydroxide containing cobalt, good cycle characteristics can be obtained.
In addition, the discharge characteristics can be made very uniform.

Further, when the average particle size of the nickel oxyhydroxide is selected in the range of 1 to 100 μm, it is possible to obtain an electrode plate having a more excellent balance between high-rate discharge characteristics and energy density.

In addition, by forming a positive electrode plate in which nickel oxyhydroxide is held in a conductive porous body having a three-dimensional structure, the energy density of the electrode plate can be further increased.

As described above, according to the present invention, the energy density of the positive electrode plate for a non-aqueous electrolyte battery using nickel oxyhydroxide as an active material can be remarkably improved, and the deterioration of the high-rate discharge characteristics can be suppressed. Can be. Therefore, an excellent nonaqueous electrolyte battery can be provided by using the positive electrode plate according to the present invention. Although the sponge-like nickel porous body was used as the active material support in the examples of the present invention, the same effect can be obtained when the active material powder is applied using a nickel mesh or a porous nickel plate as the active material support. Is obtained.

Therefore, the industrial value of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the average particle size of nickel oxyhydroxide in positive plates A and B and the amount of kneading liquid necessary for pasting.

FIG. 2 is a diagram showing the relationship between the average particle size of nickel oxyhydroxide and the energy density in positive electrode plates A, A ′, B and B ′.

FIG. 3 is a diagram showing the relationship between the discharge current density in positive electrodes A, A ′ and B ′ and the energy density of the electrodes.

FIG. 4 is a diagram showing the relationship between the number of charge / discharge cycles in the positive plates A, A ′ and B ′ and the discharge capacity retention of the active material.

[Procedure amendment]

[Submission date] May 28, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the average particle size of nickel oxyhydroxide in positive plates A and B and the amount of kneading liquid necessary for pasting.

FIG. 2 is a diagram showing the relationship between the average particle size of nickel oxyhydroxide and the energy density in positive electrode plates A, A ′, B and B ′.

FIG. 3 is a diagram showing the relationship between the discharge current density in positive electrodes A, A ′ and B ′ and the energy density of the electrodes.

FIG. 4 is a diagram showing the relationship between the number of charge / discharge cycles in the positive plates A, A ′ and B ′ and the discharge capacity retention of the active material.

FIG. 5 is an explanatory view showing a particle shape of nickel oxyhydroxide according to the present invention and a particle shape of nickel oxyhydroxide according to a conventional example.

Claims (5)

[Claims] 1. A non-aqueous electrolyte battery characterized by comprising nickel oxyhydroxide having a spherical shape and / or a shape approximate to a spherical shape, the surface of which is mainly composed of particles mainly composed of a curved surface. Positive electrode plate. 2. The positive electrode plate for a non-aqueous electrolyte battery according to claim 1, wherein nickel oxyhydroxide containing cobalt is used. 3. The nickel oxyhydroxide having an average particle size of 1
The positive electrode plate for a non-aqueous electrolyte battery according to claim 1, wherein the thickness is from 100 μm to 100 μm. 4. The positive electrode plate for a non-aqueous electrolyte battery according to claim 1, wherein the nickel oxyhydroxide is held in a conductive porous body having a three-dimensional structure. 5. A non-aqueous electrolyte battery comprising the positive electrode plate according to claim 1, 2, 3, or 4.