JP2002042890A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cycle characteristic by suppressing the oxidation decomposition of an electrolyte contacting with a positive electrode active material. SOLUTION: This nonaqueous electrolyte battery is provided with a positive electrode, a negative electrode and the nonaqueous electrolyte. The positive electrode has the positive electrode active material formed by sticking lithium- cobalt oxide grain or lithium-manganese oxide grain smaller in grain diameter than lithium-nickel oxide grain, onto the surface of the lithium-nickel oxide grain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery, and more particularly, to a non-aqueous electrolyte battery having improved cycle characteristics.

[0002]

2. Description of the Related Art In recent years, with the remarkable progress of various electronic devices, a rechargeable secondary battery has been studied as a power source that can be used conveniently and economically for a long time. Typical secondary batteries include lead storage batteries, alkaline storage batteries,
Lithium secondary batteries and the like are known. In particular, lithium secondary batteries have advantages such as high output and high energy density. The above lithium secondary battery is composed of a positive electrode capable of reversibly inserting and removing lithium ions, a negative electrode, and a nonaqueous electrolyte.

[0003]

Means for Solving the Problems While the capacity of lithium secondary batteries is increasing, the required levels of characteristics such as high-temperature characteristics and cycle characteristics are also increasing. In particular,
The cycle characteristic is one of the important characteristics at the present when the frequency of use of mobile phones and personal computer devices has rapidly increased. In recent years, compared to the lithium cobalt oxide conventionally used for the positive electrode,
Attempts have been made to realize a high-capacity battery using lithium nickel oxide as a positive electrode. When lithium nickel oxide is used for the positive electrode, the current resistance component at the time of charging tends to increase more than the conventional lithium cobalt oxide. The reason for this is that lithium nickel oxide is a compound having a high catalytic activity, and since it is in a noble potential state in a battery, oxygen reacts with the electrolyte to form an inert film (high resistance value). is there. On the other hand, when lithium cobalt oxide or lithium manganese oxide is used for the positive electrode, the above-described reaction relatively hardly proceeds because of its low catalytic function.

[0004] Lithium nickelate and its derivatives deteriorate in capacity as charge / discharge cycles are repeated. The cause includes a plurality of factors such as structural deterioration. Decomposition of the electrolyte at a noble potential and film formation are also one of the primary factors.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned conventional circumstances, and a non-aqueous electrolyte battery having improved cycle characteristics by suppressing oxidative decomposition of an electrolyte which is in contact with a positive electrode active material. The purpose is to provide.

[0006]

A non-aqueous electrolyte battery according to the present invention comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte. It has a positive electrode active material on which lithium cobalt oxide particles or lithium manganese oxide particles having a small particle diameter are adhered.

In the nonaqueous electrolyte battery according to the present invention as described above, as a positive electrode active material, lithium cobalt oxide particles or lithium cobalt oxide particles having a smaller particle diameter than the lithium nickel oxide particles are provided on the surface of the lithium nickel oxide particles. Since the manganese oxide particles are provided, the surface catalytic function of the lithium nickel oxide particles is reduced, and the generation of an inert film due to the reaction between the nonaqueous electrolyte and oxygen is suppressed. .

[0008]

Embodiments of the present invention will be described below.

FIG. 1 shows an example of the configuration of a nonaqueous electrolyte battery to which the present invention is applied. This non-aqueous electrolyte battery 1 includes a negative electrode 2,
A negative electrode can 3 containing the negative electrode 2, a positive electrode 4, a positive electrode can 5 containing the positive electrode 4, a separator 6 disposed between the positive electrode 4 and the negative electrode 2, and an insulating gasket 7; The positive electrode can 5 is filled with a non-aqueous electrolyte.

The negative electrode 2 is made of, for example, a metal lithium foil serving as a negative electrode active material. When a material that can be doped and dedoped with lithium is used as the negative electrode active material, the negative electrode 2 is formed by forming a negative electrode active material layer containing the negative electrode active material on a negative electrode current collector. As the negative electrode current collector, for example, a nickel foil or the like is used.

As the negative electrode active material which can be doped with and dedoped with lithium, lithium metal, a lithium alloy, a conductive polymer doped with lithium, and a layered compound (such as a carbon material and a metal oxide) are used.

As the binder contained in the negative electrode active material layer, a known resin material or the like usually used as a binder for the negative electrode active material layer of this type of nonaqueous electrolyte battery can be used.

The negative electrode can 3 houses the negative electrode 2 and serves as an external negative electrode of the nonaqueous electrolyte battery 1.

The positive electrode 4 is formed by forming a positive electrode active material layer containing a positive electrode active material on a positive electrode current collector. As the positive electrode current collector, for example, an aluminum foil or the like is used.

Here, in the present invention, as the positive electrode active material,
Formula _{Li x Ni 1-y M y} O 2 ( where, M is Al, B, C
It is an element containing at least one of o and Mn, and 0 ≦ y ≦ 0.5. ), And a mixture of lithium cobalt oxide or lithium manganese oxide having a finer particle diameter than the lithium nickel oxide particles, specifically, as shown in FIG. Particles in which the lithium cobalt oxide particles or the lithium manganese oxide particles 11 are attached to the surface of the lithium nickel oxide particles 10 are used.

As described above, in a non-aqueous electrolyte battery using lithium nickel oxide as a positive electrode active material, a reaction between the non-aqueous electrolyte and oxygen is caused by the high surface catalytic function of lithium nickel oxide. The inert film generated by the above has been a major cause of lowering the charge / discharge characteristics of the battery.

In the present invention, the surface catalytic function of the lithium nickel oxide particles is reduced by depositing lithium cobalt oxide particles or lithium manganese oxide particles having a low surface catalytic function on the surface of the lithium nickel oxide particles. Let me know. A nonaqueous electrolyte battery using such a positive electrode active material has excellent charge / discharge characteristics by suppressing the formation of an inert film due to the reaction between the nonaqueous electrolyte and oxygen.

As the lithium cobalt oxide particles, general formula Li _x Co _{1 -z} Al _z O ₂ (0.00 ≦ z ≦ 0.05)
It is preferable to use those represented by 0). LiCoO ₂ (z = 0.0) as lithium cobalt oxide particles
Although the effect of improving the cycle characteristics is observed even when the material represented by the formula (0) is used, the effect is further increased by using particles to which Al is added. However, the addition of Al lowers the charge / discharge capacity of the positive electrode active material, so that it is at most 5 mol% (meaning that z ≦ 0.050 in the above chemical formula) from the viewpoint of practical use. .

On the other hand, as the lithium manganese oxide particles, those represented by the general formula LiMnO ₂ are preferable. This LiMnO ₂ has several polymorphs such as a layer type and a zigzag type, and any of them may be used.

In order to deposit lithium cobalt oxide particles or lithium manganese oxide particles on the surface of lithium nickel oxide particles, for example, lithium nickel oxide particles, lithium cobalt oxide particles or lithium manganese oxide particles, Is stirred at a high speed to cause the lithium cobalt oxide particles or lithium manganese oxide particles to collide with the surface of the lithium nickel oxide particles. It can be carried out by a so-called hybridization method in which the particles are implanted and fixed on the surface of the nickel oxide particles.

Here, since the effect of the cobalt or manganese particles adhering to the lithium nickel oxide particles is a surface effect, the amount of the nickel positive electrode active material particles may be extremely small. Specifically, the average particle size of the lithium nickel oxide particles is Ra, and the average particle size of the lithium cobalt oxide particles or the lithium manganese oxide particles is Rb.
In this case, Ra and Rb satisfy 0 <Rb / Ra <0.
It is preferable to satisfy the relationship of 05.

However, the average particle diameter Ra of the lithium nickel oxide particles is in the range of 3.0 μm ≦ Ra ≦ 10.0 μm, and the average particle diameter Rb of the lithium cobalt oxide particles or lithium manganese oxide particles is , 0.05
It is necessary that the range is 0 μm ≦ Rb ≦ 1.0 μm.

As described above, the positive electrode active material in which the lithium cobalt oxide particles or the lithium manganese oxide particles are adhered to the surface of the lithium nickel oxide particles reduces the surface catalytic function of the lithium nickel oxide particles. Therefore, the non-aqueous electrolyte battery of the present invention using this positive electrode active material has a more inactive film due to the reaction between the non-aqueous electrolyte and oxygen than the non-aqueous electrolyte battery using only lithium nickel oxide. Thus, the charge and discharge characteristics are excellent.

As the binder contained in the positive electrode active material layer, a known resin material or the like which is generally used as a binder for the positive electrode active material layer of this type of nonaqueous electrolyte battery can be used.

The positive electrode can 5 accommodates the positive electrode 4 and serves as an external positive electrode of the nonaqueous electrolyte battery 1.

The separator 6 separates the positive electrode 4 and the negative electrode 2 from each other, and may be formed of a known material which is generally used as a separator of this type of nonaqueous electrolyte battery. A polymer film is used. Also, from the relationship between lithium ion conductivity and energy density, it is necessary that the thickness of the separator be as small as possible. Specifically, the thickness of the separator is suitably, for example, 50 μm or less.

The insulating gasket 7 is incorporated in the negative electrode can 3 and is integrated therewith. The insulating gasket 7 is for preventing the leakage of the nonaqueous electrolyte filled in the negative electrode can 3 and the positive electrode can 5.

As the non-aqueous electrolyte, a solution in which an electrolyte is dissolved in an aprotic non-aqueous solvent is used.

Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone,
Tetrahydrofuran, 2-methyltetrahydrofuran,
1,3-dioxolan, 4-methyl-1,3-dioxolan, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, anisole,
Acetate, butyrate propionate and the like can be used. These non-aqueous solvents may be used alone or in combination of two or more.

As the electrolyte to be dissolved in the non-aqueous solvent, for example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , L
iBF ₄ , LiB (C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃
Examples thereof include lithium salts such as SO ₃ Li, LiCl, and LiBr. Among these lithium salts, LiP
It is preferable to use F ₆ and LiBF ₄ .

As described above, the nonaqueous electrolyte battery 1 according to the present invention uses a positive electrode active material in which lithium cobalt oxide particles or lithium manganese oxide particles are adhered to the surfaces of lithium nickel oxide particles. Therefore, the surface catalytic function of the lithium nickel oxide particles is reduced, the formation of an inert film due to the reaction between the nonaqueous electrolyte and oxygen is suppressed, and the charge / discharge characteristics are excellent.

The non-aqueous electrolyte battery 1 is manufactured, for example, as follows.

As the negative electrode 2, first, a negative electrode active material and a binder are dispersed in a solvent to prepare a negative electrode mixture of a slurry. Next, the obtained negative electrode mixture is uniformly applied on a negative electrode current collector and dried to form a negative electrode active material layer, thereby forming a negative electrode 2.
Is produced. As the binder of the negative electrode mixture, a known binder can be used, and a known additive or the like can be added to the negative electrode mixture. Further, metallic lithium serving as a negative electrode active material can be used as the negative electrode 2 as it is.

For the positive electrode 4, first, a positive electrode mixture of a slurry is prepared by dispersing a positive electrode active material and a binder in a solvent. Next, the obtained positive electrode mixture is uniformly coated on a positive electrode current collector and dried to form a positive electrode active material layer, thereby forming a positive electrode 4.
Is produced. Known binders can be used as the binder of the positive electrode mixture, and known additives and the like can be added to the positive electrode mixture.

Here, in the present invention, the lithium nickel oxide particles and the lithium cobalt oxide particles or the lithium manganese oxide particles are stirred at a high speed so that the lithium cobalt oxide particles or the lithium manganese oxide particles are lithium The particles adhered to the surface of the nickel oxide particles are used as a positive electrode active material.

The non-aqueous electrolyte is prepared by dissolving an electrolyte salt in a non-aqueous solvent.

Then, the negative electrode 2 is accommodated in the negative electrode can 3, the positive electrode 4 is accommodated in the positive electrode can 5, and a separator 6 made of a polypropylene porous film or the like is disposed between the negative electrode 2 and the positive electrode 4. The non-aqueous electrolyte is injected into the negative electrode can 3 and the positive electrode can 5, and the negative electrode can 3 and the positive electrode can 5 are caulked and fixed via the insulating gasket 7, thereby completing the non-aqueous electrolyte battery 1.

In the above embodiment, a non-aqueous electrolyte battery using a non-aqueous electrolyte has been described as an example. However, the present invention is not limited to this. The present invention is also applicable to a solid electrolyte battery using a polymer solid electrolyte containing a simple substance or a mixture thereof, and a gel electrolyte battery using a gel solid electrolyte containing a swelling solvent.

Further, in the above-described embodiment, the description has been given by taking the secondary battery as an example. However, the present invention is not limited to this, and can be applied to a primary battery. In addition, the battery of the present invention has a cylindrical shape, a square shape, a coin shape, a button shape, and the like, and its shape is not particularly limited,
In addition, various sizes such as a thin type and a large size can be used.

[0040]

EXAMPLES Next, examples performed to confirm the effects of the present invention will be described.

First, in Examples 1 to 7, LiMnO ₂ was used as particles mixed with lithium nickel oxide particles.
An example in the case of using is shown.

Example 1 First, as lithium nickel oxide particles, LiNi _0.8 Co _0.2 having Ra = 1.00 μm was used.
As O ₂ , particles of LiMnO ₂ with Rb = 0.05 μm were used as particles to be mixed with the lithium nickel oxide, and a positive electrode active material was obtained by mixing both of them. When these particles are mixed, the distribution weight ratio (lithium cobalt oxide, lithium manganese oxide / lithium nickel oxide mixed with lithium nickel oxide particles) is determined by comparing the surface of the lithium nickel oxide particles. It was set to 0.01 which is a sufficient amount for sufficiently covering. The mixing conditions were such that stirring was performed for 20 minutes in dry air.

Using the obtained positive electrode active material, a coin-type non-aqueous electrolyte secondary battery was manufactured as follows.

First, a positive electrode mixture was prepared by uniformly mixing 80% by weight of a positive electrode active material, 15% by weight of graphite as a conductive agent, and 5% by weight of polyvinylidene fluoride as a binder. In addition, Lonza KS-1 having an average particle diameter of 5 μm to 20 μm is included in the weight% graphite.
5 was used. As the polyvinylidene fluoride, # 1300 manufactured by Aldrich was used.

Next, this positive electrode mixture was applied onto an aluminum mesh as a current collector, compressed, and dried in a dry argon atmosphere at 100 ° C. for 1 hour to form a positive electrode active material layer. Then, the aluminum mesh on which the positive electrode active material layer was formed was punched into a disk having a diameter of 15.5 mm to obtain a pellet-shaped positive electrode. Note that one positive electrode carries 60 mg of the positive electrode active material. A negative electrode was obtained by punching a lithium metal foil into substantially the same shape as the positive electrode.

Further, LiPF ₆ was added to a mixed solvent of propylene carbonate and dimethyl carbonate in an equal volume of 1 m.
A non-aqueous electrolyte was prepared by dissolving at a concentration of ol / l.

The positive electrode obtained as described above was accommodated in a positive electrode can, the negative electrode was accommodated in a negative electrode can, and a separator was disposed between the positive electrode and the negative electrode. A non-aqueous electrolyte solution was injected into the positive and negative electrode cans, and the positive and negative electrode cans were caulked and fixed, thereby producing a 2025-type coin-type test cell. The above steps were all performed in a dry atmosphere.

Example 2 LiNi _0.8 Co _0.2 O ₂ with Ra = 1.00 μm was used as lithium nickel oxide particles, and LiMnO ₂ with Rb = 1.0 μm was used as particles mixed with lithium nickel oxide. Thus, a positive electrode active material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 using the obtained positive electrode active material.

Example 3 Lithium nickel oxide particles
As Ra = 3.0 μm LiNi_0.8Co_0.2O _TwoFor
For particles mixed with lithium nickel oxide,
Rb = 0.05 μm LiMnO_TwoUsing positive electrode active material
I got

Then, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 using the obtained positive electrode active material.

Example 4 Lithium nickel oxide particles
As Ra = 3.0 μm LiNi_0.8Co_0.2O _TwoFor
For particles mixed with lithium nickel oxide,
Rb = 1.0 μm LiMnO_TwoUsing the positive electrode active material
Obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 5 LiNi _0.8 Co _0.2 O ₂ with Ra = 10.0 μm was used as lithium nickel oxide particles, and LiMnO ₂ with Rb = 0.05 μm was used as particles mixed with lithium nickel oxide. To obtain a positive electrode active material.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 6 LiNi _0.8 Co _0.2 O ₂ with Ra = 10.0 μm was used as lithium nickel oxide particles, and LiMnO ₂ with Rb = 1.0 μm was used as particles mixed with lithium nickel oxide. Thus, a positive electrode active material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 7 LiNi _0.8 Co _0.2 O ₂ with Ra = 10.0 μm was used as lithium nickel oxide particles, and LiMnO ₂ with Rb = 3.0 μm was used as particles mixed with lithium nickel oxide. Thus, a positive electrode active material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

In the following Examples 8 to 14,
Li as particles to be mixed with lithium nickel oxide particles
An example in which CoO ₂ is used will be described.

Example 8 LiNi _0.8 Co _0.2 O ₂ with Ra = 1.00 μm was used as lithium nickel oxide particles, and LiCoO ₂ with Rb = 0.05 μm was used as particles mixed with lithium nickel oxide. Thus, a positive electrode active material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 9 LiNi _0.8 Co _0.2 O ₂ with Ra = 1.00 μm was used as lithium nickel oxide particles, and LiCoO ₂ with Rb = 1.0 μm was used as particles mixed with lithium nickel oxide. Thus, a positive electrode active material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 10 Lithium nickel oxide particles
LiNi of Ra = 3.0 μm as a child_0.8Co_0.2O _TwoTo
Used as particles mixed with lithium nickel oxide
Is LiCoO with Rb = 0.05 μm_TwoUsing the positive electrode
Material was obtained.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

<Example 11> Lithium nickel oxide particles
LiNi of Ra = 3.0 μm as a child_0.8Co_0.2O _TwoTo
Used as particles mixed with lithium nickel oxide
Is LiCoO with Rb = 1.0 μm_TwoUsing positive electrode active material
I got the quality.

Using the obtained positive electrode active material, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1.

Example 12 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
And LiCoO ₂ with Rb = 0.05 μm was used as particles to be mixed with the lithium nickel oxide to obtain a positive electrode active material.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 13 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
And a positive electrode active material was obtained using LiCoO ₂ with Rb = 1.0 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type nonaqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 14 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
A positive electrode active material was obtained by using LiCoO ₂ with Rb = 3.0 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Further, the following Examples 15 to 21 show examples in which LiCo _0.96 Al _0.04 O ₂ is used as particles to be mixed with lithium nickel oxide particles.

Example 15 LiNi _0.8 Co _0.2 O _{2 with} Ra = 1.00 μm as lithium nickel oxide particles
A positive electrode active material was obtained using LiCo _0.96 Al _0.04 O ₂ with Rb = 0.05 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 16 LiNi _0.8 Co _0.2 O _{2 with} Ra = 1.00 μm as lithium nickel oxide particles
A positive electrode active material was obtained using LiCo _0.96 Al _0.04 O ₂ with Rb = 1.0 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 using the obtained positive electrode active material.

Example 17 Lithium Nickel Oxide Particles
LiNi of Ra = 3.0 μm as a child_0.8Co_0.2O _TwoTo
Used as particles mixed with lithium nickel oxide
Is LiCo of Rb = 0.05 μm_0.96Al_0.04O_TwoTo
To obtain a positive electrode active material.

Then, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 using the obtained positive electrode active material.

Example 18 Lithium Nickel Oxide Particles
LiNi of Ra = 3.0 μm as a child_0.8Co_0.2O _TwoTo
Used as particles mixed with lithium nickel oxide
Is LiCo of Rb = 1.0 μm_0.96Al_0.04O_TwoFor
Thus, a positive electrode active material was obtained.

Using the obtained positive electrode active material, a coin-type non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1.

Example 19 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
A positive electrode active material was obtained using LiCo _0.96 Al _0.04 O ₂ with Rb = 0.05 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 20 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
A positive electrode active material was obtained using LiCo _0.96 Al _0.04 O ₂ with Rb = 1.0 μm as particles to be mixed with lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Example 21 LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm as lithium nickel oxide particles
And a positive electrode active material was obtained using LiCo _0.96 Al _0.04 O ₂ with Rb = 3.0 μm as particles to be mixed with the lithium nickel oxide.

Then, a coin-type non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 using the obtained positive electrode active material.

Comparative Example 1 Lithium nickel oxide particles
As Ra = 1.0 μm LiNi_0.8Co_0.2O _Twoonly
Using as a positive electrode active material,
A non-aqueous electrolyte secondary battery was fabricated.

<Comparative Example 2> Lithium nickel oxide particles
As Ra = 3.0 μm LiNi_0.8Co_0.2O _Twoonly
Using as a positive electrode active material,
A non-aqueous electrolyte secondary battery was fabricated.

Comparative Example 3 A coin-type non-aqueous electrolyte secondary solution was prepared in the same manner as in Example 1 except that only LiNi _0.8 Co _0.2 O _{2 with} Ra = 10.0 μm was used as the positive electrode active material as lithium nickel oxide particles. A battery was manufactured.

Then, the cycle characteristics of the coin-type nonaqueous electrolyte secondary battery produced as described above were evaluated. First, until the voltage reaches 4.2 V, the current density is 18 mA / g.
(Positive active material weight standard)
Until the voltage reached 4.2 V. On the other hand, in discharging, the CCV was measured until the current density reached 3.0 V to obtain the capacity. All charging and discharging were performed at room temperature. Then, the charge and discharge under the above conditions were repeated 100 times, and the ratio (%) of the 100th capacity to the first capacity was determined as the charge and discharge efficiency.

First, in Examples 1 to 7 using LiMnO ₂ as particles to be mixed with lithium nickel oxide particles, the particle diameters of lithium nickel oxide particles and mixed particles (LiMnO ₂ ) and the discharge capacity of the battery Table 1 shows the relationship with the maintenance ratio.

[0095] In Table 1 and Tables 2 and 3 below, the horizontal column indicates the particle size Ra of the lithium nickel oxide particles.
And the column indicates the particle size Rb of the mixed particles. And
The numbers in the columns where the respective particle diameters intersect indicate the discharge capacity retention ratio (%) of the battery manufactured using the particles having the particle diameter.

[0096]

[Table 1]

As is clear from Table 1, Examples 1 to 7 in which LiMnO ₂ particles were mixed with lithium nickel oxide particles were compared with Comparative Examples 1 to 3 in which only lithium nickel oxide particles were used. It can be seen that all of the batteries obtained high capacity retention rates.

Among them, especially, the average particle diameter Ra of the lithium nickel oxide particles is 3.0 μm ≦ Ra ≦ 10.0
μm, and the average particle diameter Rb of the LiMnO ₂ particles.
It can be seen that particularly good values were obtained in the case of Examples 3 to 7 in which the range of 0.050 μm ≦ Rb ≦ 1.0 μm was satisfied.

Further, among them, Examples 3 and 4 in which the average particle diameter Ra of the lithium nickel oxide particles and the average particle diameter Rb of the LiMnO ₂ particles satisfy the relation of 0 <Rb / Ra <0.05. In Example 5, the effect of the present invention is remarkably exhibited, and it can be seen that the charge-discharge cycle characteristics are extremely excellent.

Next, in Examples 8 to 14 in which LiCoO ₂ was used as particles to be mixed with lithium nickel oxide particles, the particle diameters of lithium nickel oxide particles and mixed particles (LiCoO ₂ ) and the discharge of the battery Table 2 shows the relationship with the capacity retention ratio.

[0101]

[Table 2]

As is clear from Table 2, Examples 8 to 14 in which LiCoO ₂ particles were mixed with lithium nickel oxide particles were compared with Comparative Examples 1 to 3 using only lithium nickel oxide particles. It can be seen that all of the batteries obtained high capacity retention rates.

In particular, the average particle diameter Ra of the lithium nickel oxide particles is 3.0 μm ≦ Ra ≦ 10.0
μm, and the average particle size Rb of the LiCoO ₂ particles
It can be seen that particularly good values are obtained in Examples 10 to 14 in which the range of 0.050 μm ≦ Rb ≦ 1.0 μm is satisfied.

Among them, Examples 10 and 10 in which the average particle diameter Ra of lithium nickel oxide particles and the average particle diameter Rb of LiCoO ₂ particles satisfy the relationship of 0 <Rb / Ra <0.05. In Example 12, the effect of the present invention is remarkably exhibited, and it can be seen that the charge and discharge cycle characteristics are extremely excellent.

Next, mixed with lithium nickel oxide particles
LiCo as particles to be combined_0.96Al _0.04O_TwoReal using
For Examples 15 to 21, lithium nickel oxide was used.
Particles and mixed particles (LiCo_0.96Al_0.04O_Two) Grain
Table 3 shows the relationship between the diameter of the battery and the discharge capacity retention rate of the battery.

[0106]

[Table 3]

As is evident from Table 3, the lithium nickel oxide particles contained LiCo _0.96 Al as compared to Comparative Examples 1 to 3 using only lithium nickel oxide particles.
_It can be seen that the batteries of Examples 15 to 21 in which _0.04 O ₂ particles were mixed exhibited high capacity retention rates.

Among them, especially, the average particle diameter Ra of the lithium nickel oxide particles is 3.0 μm ≦ Ra ≦ 10.0
In the case of Examples 17 to 21 in which the average particle diameter Rb of the LiCo _0.96 Al _0.04 O ₂ particles is in the range of 0.050 μm ≦ Rb ≦ 1.0 μm, particularly good values are obtained. It can be seen that is obtained.

Among them, the average particle diameter Ra of the lithium nickel oxide particles and LiCo _0.96 Al _0.04 O ₂
When the average particle diameter Rb of the particles is 0 <Rb / Ra <0.05
In Examples 17 and 19 satisfying the relationship, the effect of the present invention is remarkably exhibited, and it can be seen that the charge and discharge cycle characteristics are extremely excellent.

FIG. 3 shows the relationship between the particle diameter of the adhered particles and the obtained battery capacity retention rate for lithium nickel oxide particles having a particle diameter of 1.0 μm. Further, the particle diameter is 3.
FIG. 4 shows the relationship between the particle diameter of the adhered particles and the obtained battery capacity retention ratio for lithium nickel oxide particles of 0 μm.
Shown in FIG. 4 shows the relationship between the particle size of the adhered particles and the obtained battery capacity retention ratio for lithium nickel oxide particles having a particle size of 10.0 μm.

In FIGS. 3 to 5, Li as the adhered particles was used.
The case where MnO ₂ particles are used is indicated by Δ, and the case where LiCoO ₂ particles are used as adhered particles is indicated by ●. In addition, when LiCo _0.96 Al _0.04 O ₂ was used as the adhered particles,
Indicated by The horizontal dotted lines shown in FIGS. 3 to 5 show the capacity retention ratios when the adhered particles are not mixed, that is, when only the lithium nickel oxide particles are used.

As is apparent from FIGS. 3 to 5, the same tendency is exhibited regardless of the type of the adhered particles. By adhering the adhered particles on the surface of the lithium nickel oxide particles,
It can be seen that a battery having a high capacity retention rate can be obtained. And the particle diameter of the adhered particles is 0.050 μm ≦ Rb ≦ 1.0
It can be seen that particularly good values are obtained in the range of μm.

[0113]

According to the present invention, a positive electrode in which the surface catalytic function of lithium nickel oxide particles is reduced by depositing lithium cobalt oxide particles or lithium manganese oxide particles on the surfaces of lithium nickel oxide particles. An active material is obtained. Therefore, in the present invention, by using this positive electrode active material, generation of an inert film due to the reaction between the nonaqueous electrolyte and oxygen can be suppressed, and a nonaqueous electrolyte battery having excellent charge / discharge characteristics can be realized. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration example of a nonaqueous electrolyte battery according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a state where lithium cobalt oxide particles or lithium manganese oxide particles are adhered to the surface of lithium nickel oxide particles.

FIG. 3 is a graph showing the relationship between the particle size of adhered particles and the capacity retention of the obtained battery for lithium nickel oxide particles having a particle size of 1.0 μm.

FIG. 4 is a graph showing the relationship between the particle size of adhered particles and the obtained battery capacity retention rate for lithium nickel oxide particles having a particle size of 3.0 μm.

FIG. 5 is a diagram showing the relationship between the particle size of adhered particles and the obtained battery capacity retention rate for lithium nickel oxide particles having a particle size of 10.0 μm.

[Explanation of symbols]

1 Non-aqueous electrolyte battery 1, 2 Negative electrode, 3 Negative electrode can,
4 positive electrode, 5 positive electrode can, 6 separator, 7 insulating gasket

Claims (6)

[Claims] 1. A non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode has a surface on which lithium nickel oxide particles have a smaller particle diameter than the lithium nickel oxide particles. A non-aqueous electrolyte battery comprising a positive electrode active material to which cobalt oxide particles or lithium manganese oxide particles are adhered. 2. An average particle diameter Ra of the lithium nickel oxide particles and an average particle diameter Rb of the lithium cobalt oxide particles or lithium manganese oxide particles are 0 <.
2. The non-aqueous electrolyte battery according to claim 1, wherein a relationship of Rb / Ra <0.05 is satisfied. 3. The lithium nickel oxide particles have an average particle diameter Ra in a range of 3.0 μm ≦ Ra ≦ 10.0 μm, and the lithium cobalt oxide particles or lithium manganese oxide particles have an average particle diameter Rb. , 0.050 μm ≦ Rb
2. The non-aqueous electrolyte battery according to claim 1, wherein the range is ≦ 1.0 μm. 4. The lithium cobalt oxide particles according to the general formula Li _x Ni _{1 -y My} O ₂ (M is an element containing at least one of Al, B, Co and Mn, and ≦ y ≦
0.5. 2. The method according to claim 1, wherein
The non-aqueous electrolyte battery according to the above. 5. The method according to claim 1, wherein the lithium cobalt oxide particles have a general formula of LiCo _1-z Al _z O ₂ (0.00 ≦ z ≦ 0.05).
The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is represented by the following formula: 6. The lithium manganese oxide particles are represented by a general formula LiMnO _2.
The non-aqueous electrolyte battery according to the above.