JPH07312221A - Positive electrode black mix - Google Patents

Abstract

PURPOSE:To provide nonaqueous electrolyte battery having high energy density per battery volume, especially lithium battery, by improving charging rate of a positive active material per positive electrode black mix unit volume. CONSTITUTION:A positive electrode black mix contains a positive electrode A active material, conductive agent, and binder. A positive electrode active material whose longest particle radius of each one of particles of positive electrode active materials is set to 1.00-1.20 times of the mean particle radius of each positive electrode active material particles and whose shortest particle radius is set to 0.80-1.00 time of the mean particle radius is used for the positive electrode black mix.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode mixture for a non-aqueous electrolyte battery such as a lithium battery and a non-aqueous electrolyte battery using the positive electrode mixture.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries and lithium batteries include primary batteries and secondary batteries using a chalcogen compound as a positive electrode active material and metallic lithium or a carbonaceous material as a negative electrode. Such a battery is constructed by mixing positive electrode active material particles, carbon particles such as graphite and acetylene black, which are conductive agents, and polytetrafluoroethylene as a binder for each particle, and an organic solid electrolyte. Then, a positive electrode is formed by filling or coating a substrate such as a stainless net or a stainless plate into a sheet shape, and a metallic lithium sheet or a stainless plate, which is the negative electrode, is connected to the metallic lithium sheet, the carbonaceous material and the above-mentioned binder through a separator. Mix the adhesive to make a paste, fill or apply it to a substrate such as a stainless steel net or stainless steel plate, and put the sheet-shaped products together to store them in a battery can or the periphery of the stainless steel plate. A cell was filled with a sealing agent to form a battery.

[0003]

The positive electrode active material has an irregular particle shape and a longest particle radius of 1.
Over 20 times the shortest particle radius is 0.80 of the average particle radius
It is less than double and the filling rate of the positive electrode active material per unit volume of the positive electrode mixture is low. Therefore, the energy density per battery volume is currently low. Furthermore, regarding the conductive agent, when a particle shape such as graphite having an irregular shape or a secondary particle such as acetylene black or a material having a tertiary particle structure is used as the conductive agent, the positive electrode active material per unit volume of the positive electrode mixture Causes a low filling rate.

The present invention has been made to solve this problem, and its purpose is to increase the filling rate of the positive electrode active material per unit volume of the positive electrode mixture to increase the energy density per battery volume. To provide a high-performance non-aqueous electrolyte battery, particularly a lithium battery.

[0005]

In order to achieve the above object, a positive electrode mixture of the present invention and a battery using the positive electrode mixture have a positive electrode active material in which each one of the particles of the positive electrode active material is The longest particle radius is 1.0 of the average particle radius with respect to the average particle radius of one particle of each positive electrode active material.
0 times to 1.20 times, the shortest particle radius is 0.
80 times to 1.00 times the positive electrode active material, and 1 particle of each of the conductive agent particles as the conductive agent.
The longest particle radius is 1.00 to 1.20 times the average particle radius, and the shortest particle radius is 0.80 to 1.00 times the average particle radius with respect to the average particle radius of the particles of each conductive agent. Is used. 1 and 2 are cross-sectional views of one positive electrode active material and one conductive agent particle of the present invention, respectively.

In the positive electrode active material of the present invention, one particle of each positive electrode active material has a longest particle radius of 1 with respect to the average particle radius of one particle of the positive electrode active material. 0.001 times to 1.20 times, the shortest particle radius is 0.80 times to 1.00 times the average particle radius, and the average particle radius of each one particle of the positive electrode active material and the positive electrode active material is 60 μm. When the following positive electrode active material and the mixture of the positive electrode active material in the present invention and the other positive electrode active material are taken as 100% by weight, the positive electrode active material in the present invention is 20% by weight or more in the present invention. The use of the positive electrode mixture improves the active material filling rate per unit volume of the positive electrode mixture, and the use of the positive electrode mixture in the non-aqueous electrolyte battery of the present invention improves the energy density per battery volume. .

Each of the particles of the positive electrode active material has the longest particle radius exceeding 1.20 times the average particle radius with respect to the average particle radius of each one particle of the positive electrode active material. A positive electrode active material having a shortest particle radius of less than 0.80 times the average particle radius and a positive electrode active material particle of 1
20% by weight of the positive electrode active material in the present invention is defined as 100% by weight of a mixture of the positive electrode active material having an average particle radius of 60 μm or more and the positive electrode active material in the present invention and other positive electrode active materials. The positive electrode mixture using less than the positive electrode active material and the non-aqueous electrolyte battery using the positive electrode mixture do not improve the active material filling rate per unit volume of the positive electrode mixture and the energy density per battery volume.

In the positive electrode active material according to the present invention, one particle of the positive electrode active material is one particle of the positive electrode active material, and the longest particle radius is the average particle radius. 1.00 times to 1.10 times, and the positive electrode active material having the shortest particle radius of 0.90 times to 1.00 times the average particle radius, and the positive electrode active material of the present invention and other positive electrode active materials were mixed. It is preferable to use the positive electrode active material in which the positive electrode active material in the present invention is 50% by weight or more when 100% by weight is used for the positive electrode mixture of the present invention and the non-aqueous electrolyte battery using the positive electrode mixture.

In the conductive agent in the present invention, one of the particles of the conductive agent has a longest particle radius of 1.00 times the average particle radius with respect to the average particle radius of one particle of the conductive agent. 1.20 times, conductive agent having the shortest particle radius 0.80 times to 1.00 times the average particle radius, conductive agent having an average particle radius of 5 μm or less for each one particle of the conductive agent, Further, when the mixture of the conductive agent and the positive electrode active material in the present invention is 100% by weight, the mixture of the conductive agent in the present invention of 1 to 25% by weight or more is used in the positive electrode mixture of the present invention to obtain a positive electrode mixture. The active material filling rate per unit volume is improved, and the energy density per battery volume is improved by using the positive electrode mixture in the non-aqueous electrolyte battery of the present invention.

One particle of each of the conductive agent particles has an average particle radius of one particle of the conductive agent.
The average particle radius of the particles having the longest particle radius exceeding 1.20 times the average particle radius, the shortest particle radius being less than 0.80 times the average particle radius, and one particle each of the conductive agent particles. Is more than 5 μm and the mixture of the conductive agent in the present invention and the positive electrode active material is 100% by weight, the positive electrode mixture and the positive electrode mixture using the mixture in which the conductive agent in the present invention is 1 to 25% by weight. The non-aqueous electrolyte battery using the agent does not improve the active material filling rate per unit volume of the positive electrode mixture and the energy density per cell volume.

In the conductive agent of the present invention, one of the particles of the conductive agent is one particle of the conductive agent, and the longest particle radius is 1.00 of the average particle radius. When the amount of the conductive agent having the shortest particle radius of 0.90 times to 1.00 times the average particle radius and the mixture of the conductive agent and the positive electrode active material of the present invention is 100% by weight. The conductive agent in the present invention is 1 to 1
It is preferable to use the mixture of 0% by weight for the positive electrode mixture of the present invention and the non-aqueous electrolyte battery using the positive electrode mixture.

The positive electrode active material used in the positive electrode mixture of the present invention is MnO _{2 for} a primary battery, MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , LiV ₃ O ₈ for a secondary battery, Li
Mn ₂ O ₄ , LiCoO ₂ , LiCrO ₂ , LiNiO
There are ₂ etc., but not limited to these. Further, as the conductive agent, there are graphite, carbon black, metal powder, conductive ceramics, conductive polymers, etc.
Not limited.

The positive electrode is kneaded with, for example, the above-mentioned positive electrode active material, a conductive agent and a binder such as polytetrafluoroethylene, polyvinylidene fluoride, and an ion conductive polymer solid electrolyte material to prepare a positive electrode mixture, and then the positive electrode mixture is prepared. Is rolled or applied to a foil or the like made of aluminum or stainless steel as a current collector, and cured.

[0014]

In the positive electrode mixture of the present invention and the non-aqueous electrolyte battery using the positive electrode mixture, the active material filling rate per unit volume of the positive electrode mixture is improved, and the energy density per battery volume is improved. The reason for this is that, when a positive electrode mixture is produced using the positive electrode active material and the conductive agent in the present invention, the particle shape of the positive electrode active material and the conductive agent is limited to be as spherical as possible. The number of contact between particles in the agent is large, the contact area is large, and the particles overlap each other more closely. Then, the volume other than the positive electrode active material and the conductive agent is reduced, and the active material filling rate per unit volume of the positive electrode mixture is increased. In the case of using a positive electrode active material other than the present invention, if the particle shape is irregular and particles are randomly present in the positive electrode mixture, the number of contact between the particles is smaller than that of the present invention, and the contact area is also Therefore, the volume other than the positive electrode active material and the conductive agent is increased, and the positive electrode active material filling rate per unit volume of the positive electrode mixture is reduced. Further, when the mixture of the positive electrode active material in the present invention and the positive electrode active material other than the present invention is 100% by weight,
When the content of the positive electrode active material is 20% by weight or more, the filling rate of the positive electrode active material per unit volume of the positive electrode mixture is improved as compared with the conventional one. The average particle radius of the positive electrode active material is 6
If it exceeds 0 μm, cations such as Li ions in the positive electrode active material are less likely to diffuse during discharge or charge, and discharge characteristics or charge characteristics are deteriorated, which is not preferable. When the average particle radius of the conductive agent of the present invention exceeds 5 μm, the number of conductive agents present in the positive electrode mixture decreases, the contact area of the conductive agent also decreases, and the electron conduction in the positive electrode mixture decreases. However, the discharge or charge characteristics will deteriorate.
When the mixture of the positive electrode active material of the present invention and the conductive agent of the present invention is 100% by weight, when the amount of the conductive agent is less than 1% by weight, electron conduction in the positive electrode mixture is reduced and discharge or charge characteristics are deteriorated. I will end up. If it exceeds 25% by weight, the proportion of the positive electrode active material in the positive electrode mixture will be small, and as a result, the positive electrode active material filling rate per unit volume of the positive electrode mixture will decrease.

[0015]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by the examples described below, and various modifications may be made without departing from the scope of the invention. Is possible.

As a positive electrode active material for a primary battery, one particle of each of the positive electrode active material of the present invention is the average particle radius of the particles of one positive electrode active material, and the longest particle radius is the average particle radius. 1.00 times to 1.20 times, the shortest particle radius is 0.80 times to 1.00 times the average particle radius, and 100 g of MnO _{2 in} which the average particle radius of the particles of the positive electrode active material is 60 μm or less. The longest particle radius is 1.00 times to 1 times the average particle radius with respect to the average particle radius of each one particle of the conductive agent of the present invention as the conductive agent. 20 times, the shortest particle radius is 0.80 times to 1.00 times the average particle radius,
10 g of graphite having an average particle radius of 5 μm or less of the conductive agent is mixed, 40 g of an ion conductive polymer solid electrolyte material as a binder, and 0.025 g of azobisisobutyronitrile as a reaction initiator are further mixed. A positive electrode mixture paste was obtained. The ion conductive polymer solid electrolyte material is obtained by dissolving a mixture of ethylene oxide monoacrylate, diacrylate and triacrylate in LiClO ₄ in propylene carbonate.

Next, the above positive electrode mixture paste is cast on a stainless steel substrate, and the paste is applied at 100 ° C. in an inert gas atmosphere.
The mixture was left to stand for a period of time to be cured to obtain a sheet-shaped positive electrode mixture on a stainless steel substrate. The thickness of the obtained positive electrode mixture was about 250 μm.

Next, azobisisobutyronitrile 0.05
What was dissolved in 100 g of the above ion conductive polymer solid electrolyte material was cast on the above positive electrode mixture and cured in the same manner as above, and an ion conductive polymer solid electrolyte film was formed as a separator on the above positive electrode mixture. Formed. The thickness of the obtained coating was 20 μm.

A composite sheet comprising the stainless steel substrate, the positive electrode mixture, and the ion conductive polymer solid electrolyte coating obtained as described above was cut into a size of 1 cm × 1 cm, and the ion conductive polymer of this composite sheet was cut out. Metallic lithium having a thickness of 100 μm is attached as a negative electrode on the solid electrolyte coating, and has a structure shown in FIG. 3, that is, a stainless substrate 9, a positive electrode mixture 10, an ion conductive polymer solid electrolyte coating 11, a negative electrode 12, and a stainless substrate. A battery consisting of

A load of 1 kg / cm ² was applied to the obtained battery, and in that state, a discharge test was performed at a discharge current of 2.0 V at a constant current of 0.1 mA / cm ² at 20 ° C.

As a comparative example, each of the particles of the positive electrode active material as the positive electrode active material for the primary battery has a longest particle radius with respect to the average particle radius of one particle of the positive electrode active material. 1.22 times the average particle radius to 2.0
0 times the shortest particle radius is 0.55 times the average particle radius to 0.
79 times, the average particle radius of the particles of the positive electrode active material is 62 to 70 μm, 100 g of MnO _2, and one particle of each conductive agent as a conductive agent is 1
The longest particle radius is 1.21 to 1.40 times the average particle radius and the shortest particle radius is 0.60 to 0.77 times the average particle radius with respect to the average particle radius of the particles of the conductive agent. A battery using the positive electrode mixture prepared by the same method as above except that 10 g of graphite having an average particle radius of the conductive agent of 7 to 10 μm was mixed was also prepared by the same method as described above. However, it is the same as the above except that 65 g of the ion conductive polymer solid electrolyte and 0.033 g of azobisisobutyronitrile were required in the preparation of the positive electrode mixture paste.

As described above, the energy density per battery volume was compared from the packing density of the active material per positive electrode mixture volume and the discharge characteristics of the two types of batteries.

Tables 1 and 2 show the positive electrode active material utilization rate in the discharge test, the active material packing density per positive electrode mixture volume, and the energy density per battery volume.

[0024]

[Table 1]

[0025]

[Table 2]

As is clear from Tables 1 and 2, the positive electrode mixture of the present invention and the non-aqueous solution containing the positive electrode mixture are used in terms of the active material filling rate per unit volume of the positive electrode mixture and the energy density per battery volume. It can be seen that the electrolyte battery is superior to the conventional example.

[0027]

As is clear from the above description, one particle of the positive electrode active material is the average particle radius of the particles of the positive electrode active material, and the longest particle radius is the average particle radius. 1.00 times to 1.20 times, the shortest particle radius is 0.80 times to 1.00 times the average particle radius, the average particle radius of the particles of the positive electrode active material is 60 μm or less, and the positive electrode active material and other than the above. 100 mixed with the positive electrode active material
The mixture having the positive electrode active material in an amount of 20% by weight or more, and one particle of each of the conductive agent is the longest particle radius with respect to the average particle radius of the conductive agent particles. Is 1.00 to 1.2 times the average particle radius
0 times the shortest particle radius is 0.80 times the average particle radius-1.
00 times, the average particle radius of the conductive agent is 5 μm or less, and 100% by weight of the mixture of the positive electrode active material and the conductive agent.
Then, in the positive electrode mixture using the mixture in which the conductive agent is 1 to 25% by weight, the positive electrode active material filling rate per unit volume is improved, and in the non-aqueous electrolyte battery using the positive electrode mixture, The energy density per battery volume is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a positive electrode active material according to the present invention.

FIG. 2 is a cross-sectional view of a conductive agent according to the present invention.

FIG. 3 is a cross-sectional view of a battery in an example.

[Explanation of symbols]

 1 Longest particle radius of positive electrode active material in the present invention 2 Average particle radius of positive electrode active material in the present invention 3 Shortest particle radius of positive electrode active material in the present invention 4 Positive electrode active material 5 in the present invention Longest particle radius of conductive agent in the present invention 6 Average Particle Radius of Conductive Agent in Present Invention 7 Shortest Particle Radius of Conductive Agent in Present Invention 8 Conductive Agent in Present Invention 9 Stainless Steel Substrate 10 Positive Electrode Mixture 11 Ion Conductive Polymer Solid Electrolyte Coating 12 Negative Electrode 13 Stainless Steel Substrate

Claims (6)

[Claims] 1. A positive electrode mixture containing a positive electrode active material, a conductive agent, and a binder, each of which is one of particles of the positive electrode active material.
Each of the particles has a longest particle radius of 1.00 to 1.20 times the average particle radius and a shortest particle radius of 0 to the average particle radius of the average particle radius of one positive electrode active material particle. A positive electrode mixture characterized by using a positive electrode active material having a weight ratio of 80 to 1.00. 2. The positive electrode mixture according to claim 1, wherein the particles of the positive electrode active material have an average particle radius of 60 μm or less. 3. When the mixture of the positive electrode active material according to claim 1 and other positive electrode active material is 100% by weight,
A positive electrode mixture, wherein the positive electrode active material according to claim 1 is 20% by weight or more. 4. The longest particle radius of each one particle of the conductive agent is 1.00 to 1 times the average particle radius of the average particle radius of each one particle of the conductive agent. 20 times, the shortest particle radius is 0.80 of the average particle radius
The positive electrode mixture according to claim 1, wherein a conductive agent having a ratio of 2 to 1.00 is used. 5. The positive electrode mixture according to claim 1, wherein the conductive agent has an average particle radius of 5 μm or less. 6. When the mixture of the positive electrode active material according to claim 1, 2 and 3 and the conductive agent is 100% by weight,
A positive electrode material mixture, wherein a mixture containing 1 to 25% by weight of the conductive agent is used.