JP3182271B2 - Non-aqueous battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous battery,
More specifically, the present invention relates to improvement of a positive electrode for the purpose of improving storage characteristics of a nonaqueous battery at a high temperature.

[0002]

2. Description of the Related Art In recent years,
A non-aqueous battery using an alloy or a carbon material capable of occluding and releasing lithium metal or lithium ion as a negative electrode material and a lithium-transition metal composite oxide as a positive electrode material has been attracting attention as a battery having a high energy density.

The lithium-transition metal composite oxides include LiMnO ₂ , LiFeO ₂ and Li _x Ni ₁ -YC
o _Y O _Z (where 0 <X <1.3, 0 ≦ Y ≦ 1, 1.8
<Z <2.2) and the like are well known.
_{Li X Ni 1-Y Co Y} O Z is large capacity, is one of the positive electrode active material has received the most attention.

[0004] However, Li _X Ni _1-Y Co _Y O _Z
A non-aqueous battery using as a positive electrode active material can be stored at high temperature for a long time, especially in the case of a secondary battery, in a charged state (with lithium ions released from the positive electrode active material) for a long time at high temperature Doing so increases the internal resistance of the battery. The increase in the internal resistance is considered to be as follows.

[0005] Sunawa Chi, during charging and the lithium is released from the positive electrode active material, is greater than the number of oxidation of nickel or cobalt in the active material 3 After charging, also nickel or cobalt in the active material even when the discharge Has an oxidation number of more than 3.
Furthermore, the oxidation number of nickel or cobalt in the active material is greater than 3 even during discharge in primary batteries. When the oxidation number of nickel or cobalt exceeds 3, the electrolytic solution is decomposed by the catalytic action of these positive electrode active materials and gas is generated, and the generated gas causes deformation of the positive electrode plate shape. In addition, the adhesion between the positive electrode active material layer and the core (current collector) or the like decreases, and the internal resistance increases.

As described above, the non-aqueous battery using such a positive electrode active material has a problem that it is unsuitable as a power source for a mobile phone or the like which is left at a high temperature for a long time. It had been.

The present invention has been made to meet such a demand, and an object of the present invention is to provide a non-aqueous system using Li _X Ni _{1 -Y} Co _{YO Z} excellent in high-temperature storage characteristics as a positive electrode active material. To provide batteries.

[0008]

In order to achieve the above object, a non-aqueous battery according to the present invention (hereinafter referred to as "battery of the present invention") comprises: a negative electrode having lithium as a negative electrode active material;
i _X Ni _1-Y M _Y O _Z (where 0 <X <1.3, 0 ≦ Y
≦ 1, 1.8 <Z <2.2, and M is cobalt or two or more transition metals containing cobalt. A) a positive electrode comprising a lithium-transition metal composite oxide as a positive electrode active material, wherein the oxidation number of nickel with respect to the positive electrode active material is 3 or less and lithium is not contained in the crystal. Nickel oxide and / or cobalt oxide having an oxidation number of 3 or less and containing no lithium in the crystal is added in an amount of 0.1 to 20 mol%.

The nickel oxide and the cobalt oxide in the present invention are limited to those having an oxidation number of 3 or less. This is because electrochemically produced NiO ₂ (oxidation number of nickel: 4), CoO ₂ (oxidation number of cobalt: 4), etc., having an oxidation number of more than 3, have a catalytic action to promote decomposition of the electrolyte. This is because the increase in the internal resistance of the battery cannot be effectively suppressed.

The reason why the nickel oxide and the cobalt oxide are not limited to those containing no lithium is that when lithium is contained, the contained lithium is released by charging and the oxidation number of nickel and cobalt exceeds 3 and becomes large. To become
This is because, for the same reason as described above, the internal resistance of the battery is rather increased as compared with the case of no addition.

The addition amount of nickel oxide and cobalt oxide is regulated to 0.1 to 20 mol% with respect to the positive electrode active material. When the content exceeds 20 mol%, the internal resistance of the battery increases due to the low conductivity of these oxides, and at the time of charging and discharging, This is because the diffusion of lithium in the positive electrode becomes worse, and the charge / discharge efficiency decreases.

[0012] A mixture of nickel oxide and cobalt oxide may be added. Also in this case, it is necessary to regulate the total amount thereof within the range of 0.1 to 20 mol parts (0.1 to 20 mol%) based on 100 mol parts of the positive electrode active material.

As nickel oxide, NiO, Ni ₂
O ₃ and Ni ₃ O ₄ are exemplified as typical ones, and as the cobalt oxide, CoO and Co ₃ O ₄ are exemplified as typical ones. Among them, NiO and Co ₃ O ₄ are exemplified.
₄ is particularly preferred.

Examples of the negative electrode using lithium as the negative electrode active material in the present invention include those using metal lithium and an alloy or carbon material capable of occluding and releasing lithium ions as an electrode material.

The present _{invention, Li X Ni 1-Y Co} Y O Z decomposition of the electrolytic solution, which has been a problem when using as a positive electrode active material, the positive electrode active material of nickel oxide and / or cobalt oxide To improve the storage characteristics of non-aqueous batteries at high temperatures. Therefore, as for other members constituting the battery, such as an electrolytic solution, it is possible to use various materials which have been conventionally proposed or practically used for non-aqueous batteries without any particular limitation.

Examples of the non-aqueous electrolyte include organic solvents such as ethylene carbonate, vinylene carbonate and propylene carbonate, and dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2
- diethoxyethane, in a mixed solvent of low boiling point solvent such as ethoxymethoxy ethane, LiPF _6, LiClO _4,
A solution in which a solute such as LiCF ₃ SO ₃ is dissolved at a ratio of 0.7 to 1.5 M (mol / liter) is exemplified.

[0017]

In the present invention, nickel oxide and / or cobalt oxide act as a catalyst poison in the decomposition reaction of the electrolytic solution. Gas is hardly generated. For this reason, deformation of the electrode plate of the positive electrode is less likely to occur, and an increase in the internal resistance of the battery is suppressed.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention may be practiced by appropriately changing the gist of the invention. Is possible.

Example 1 A flat nonaqueous battery (battery of the present invention) was manufactured.

[Positive electrode] LiOH, Ni (OH) ₂ ,
After mixing with Co (OH) ₂ at a molar ratio of 2: 1: 1 in a mortar, the mixture was dried at 750 ° C. in a dry air atmosphere.
For 20 hours to obtain a positive electrode active material represented by LiNi _0.5 Co _0.5 O ₂ . Then, after pulverizing in a mortar of Ishikawa type rai so that the average particle diameter becomes 5 μm, Ni ₂ O ₃ (oxidation number of nickel:
3) 0.1 mol% of the powder was added and mixed.

Next, the positive electrode active material powder to which Ni ₂ O ₃ was added and mixed, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a weight ratio of 90: 6: 4. A positive electrode mixture was prepared, and the positive electrode mixture was molded into a disc having a diameter of 20 mm under a pressure of 2 ton / cm ² , and then heat-treated at 250 ° C. for 2 hours to produce a positive electrode.

[Negative Electrode] A rolled sheet of metallic lithium having a predetermined thickness was punched into a disc having a diameter of 20 mm to produce a negative electrode.

[Non-Aqueous Electrolyte] A non-aqueous electrolyte was prepared by dissolving lithium perchlorate at a ratio of 1 M (mol / liter) in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in an equal volume.

[Preparation of Battery] A flat type battery BA1 of the present invention was prepared using the above positive and negative electrodes and a non-aqueous electrolyte (battery dimensions: 24.0 mm in diameter, 3.0 mm in thickness). In addition,
As the separator, a microporous polypropylene film (manufactured by Hoechst Celanese Co., Ltd., trade name "Celgard") was used, and this was impregnated with the above nonaqueous electrolyte.

FIG. 1 is a cross-sectional view schematically showing the fabricated battery BA1 of the present invention. The battery BA1 of the present invention shown in FIG.
Is composed of a positive electrode 1, a negative electrode 2, a separator 3 separating the electrodes 1 and 2 from each other, a positive electrode can 4, a negative electrode can 5, a positive electrode current collector 6, a negative electrode current collector 7, an insulating packing 8 made of polypropylene, and the like. .

The positive electrode 1 and the negative electrode 2 are housed in a battery case formed with positive and negative bipolar cans 4 and 5 facing each other via a separator 3 impregnated with a non-aqueous electrolyte. The negative electrode 2 is connected to the negative electrode current collector 7 through the positive electrode can 4 through the negative electrode current collector 7.
Is connected to the negative electrode can 5 so that the chemical energy generated inside the battery can be taken out as electric energy from both terminals of the positive electrode can 4 and the negative electrode can 5.

(Examples 2 to 5) The above Example 1 was conducted except that the addition amount of the Ni ₂ O ₃ powder to the positive electrode active material powder was 5 mol%, 10 mol%, 15 mol%, and 20 mol%, respectively. In the same manner as in the above, a positive electrode was produced. Next, in the same manner as in Example 1 except that this positive electrode was used, the battery BA2 of the present invention (the amount of Ni ₂ O ₃ powder added: 5 mol%), BA
3 (addition amount of Ni ₂ O ₃ powder: 10 mol%), BA4
(Addition amount of Ni ₂ O ₃ powder: 15 mol%), BA5 (N
i ₂ O ₃ powder: 20 mol%).

(Examples 6 to 10) Positive electrodes were prepared in the same manner as in Examples 1 to 5, except that Ni ₃ O ₄ (nickel oxidation number: 2.67) powder was used instead of Ni ₂ O ₃ powder. Was prepared. Next, in the same manner as in Example 1 except that these positive electrodes were used, the batteries BA6 of the present invention (addition amount of Ni ₃ O ₄ powder: 0.1 mol%) and BA7 (addition amount of Ni ₃ O ₄ powder) were used. : 5 mol%), BA8 (Ni ₃ O ₄ powder addition amount:
10 mol%), BA9 (added amount of Ni ₃ O ₄ powder: 15)
_{Mol%), BA10 (Ni 3 O} 4 powder added amount: 20 mol%) was prepared.

Examples 11 to 15 Positive electrodes were produced in the same manner as in Examples 1 to 5, except that CoO (oxidation number of cobalt: 2) powder was used instead of Ni ₂ O ₃ powder. Next, in the same manner as in Example 1 except that these positive electrodes were used, the battery BA11 of the present invention (the amount of CoO powder added:
0.1 mol%), BA12 (addition amount of CoO powder: 5 mol%), BA13 (addition amount of CoO powder: 10 mol%), BA14 (addition amount of CoO powder: 15 mol%),
BA15 (the amount of CoO powder added: 20 mol%) was prepared.

Comparative Example 1 Ni ₂ O ₃ was added to the positive electrode active material powder.
A positive electrode was produced in the same manner as in Example 1 except that the powder was not added and mixed. Next, a comparative battery BC1 was produced in the same manner as in Example 1 except that this positive electrode was used.

(Comparative Example 2) Ni for cathode active material powder
_A positive electrode was produced in the same manner as in Example 1, except that the amount of the added ₂ O ₃ powder was 25 mol%. Next, a comparative battery B was prepared in the same manner as in Example 1 except that this positive electrode was used.
C2 was produced.

Comparative Example 3 Ni for Positive Electrode Active Material Powder
_A positive electrode was produced in the same manner as in Example 6, except that the amount of ₃ O ₄ powder added was 25 mol%. Next, a comparative battery B was prepared in the same manner as in Example 1 except that this positive electrode was used.
C3 was produced.

(Comparative Example 4) Co against cathode active material powder
Example 1 except that the addition amount of O powder was 25 mol%.
In the same manner as in Example 1, a positive electrode was produced. Next, a comparative battery BC was prepared in the same manner as in Example 1 except that this positive electrode was used.
4 was produced.

The types and amounts of nickel oxide powder or cobalt oxide powder added to the positive electrode active material powder in the preparation of each positive electrode of the batteries BA1 to BA15 of the present invention and the comparative batteries BC1 to BC4 are summarized in Table 1 below. Shown.

[0035]

[Table 1]

[Storage characteristics] Batteries BA1 to BA15 of the present invention
After charging the comparative batteries BC1 to BC4, the batteries were stored at 80 ° C. for 30 days, and the storage characteristics of each battery were examined. The results are shown in FIG. The storage characteristics were evaluated by the rate of increase (%) of the internal resistance of the battery. The internal resistance of the battery was calculated by the following equation.

Increase rate (%) of internal resistance of battery = (internal resistance after storage−internal resistance before storage) × 100 / internal resistance before storage

FIG. 2 shows the storage characteristics of each battery, the vertical axis shows the increase rate (%) of the internal resistance of the battery, and the horizontal axis shows the addition amount (mol%) of nickel oxide or cobalt oxide. It is a graph shown, as shown in FIG.
In BA15, the increase rate of the internal resistance of the battery is as low as 50% or less, whereas in Comparative Battery BC1 to BC4, the increase rate of the internal resistance of the battery is as high as 100% or more. From this, the increase in the internal resistance of the battery when stored at a high temperature indicates that the nickel oxide or cobalt oxide having an oxidation number of nickel and cobalt of 3 or less and containing no lithium in the crystal has a positive electrode activity. It can be seen that the addition is significantly suppressed by adding 0.1 to 20 mol% to the substance.

(Examples 16 to 20) Positive electrodes were produced in the same manner as in Examples 1 to 5, except that NiO (nickel oxidation number: 2) powder was used instead of Ni ₂ O ₃ powder. Next, in the same manner as in Example 1 except that these positive electrodes were used, the battery BA16 of the present invention (the amount of NiO powder added:
0.1 mol%), BA17 (addition amount of NiO powder: 5 mol%), BA18 (addition amount of NiO powder: 10 mol%), BA19 (addition amount of NiO powder: 15 mol%),
BA20 (addition amount of NiO powder: 20 mol%) was prepared.

(Examples 21 to 25) Instead of Ni ₂ O ₃ powder, NiO powder and Co ₃ O ₄ (oxidation number of cobalt: 2.
67) A positive electrode was produced in the same manner as in Examples 1 to 5, except that an equimolar mixture with powder was used. Next, in the same manner as in Example 1 except that these positive electrodes were used, the batteries BA21 of the present invention (total amount of NiO powder and Co ₃ O ₄ powder: 0.1 mol%) and BA22 (total of both powders) were used. Addition amount: 5
Mol%), BA23 (total addition amount of both powders: 10 mol%), BA24 (total addition amount of both powders: 15 mol%), B
A25 (total addition: 20 mol%) was prepared.

Examples 26 to 30 Positive electrodes were produced in the same manner as in Examples 1 to 5, except that Co ₃ O ₄ powder was used instead of Ni ₂ O ₃ powder. Next, the battery B of the present invention was prepared in the same manner as in Example 1 except that these positive electrodes were used.
A26 (Co ₃ O ₄ powder addition amount: 0.1 mol%), B
A27 (addition amount of Co ₃ O ₄ powder: 5 mol%), BA2
8 (addition amount of Co ₃ O ₄ powder: 10 mol%), BA29
(Amount of Co ₃ O ₄ powder added: 15 mol%), BA30
(Co ₃ O ₄ powder added: 20 mol%).

Comparative Example 5 Ni for Positive Electrode Active Material Powder
Example 1 except that the addition amount of O powder was 25 mol%.
In the same manner as in 6, a positive electrode was produced. Next, a comparative battery BC was prepared in the same manner as in Example 1 except that this positive electrode was used.
5 was produced.

Comparative Example 6 Ni for Positive Electrode Active Material Powder
A positive electrode was produced in the same manner as in Example 21 except that the total amount of the O powder and the Co ₃ O ₄ powder was 25 mol%.
Next, a comparative battery BC6 was produced in the same manner as in Example 1 except that this positive electrode was used.

(Comparative Example 7) Co with respect to the positive electrode active material powder
_A positive electrode was produced in the same manner as in Example 26 except that the addition amount of the ₃ O ₄ powder was 25 mol%. Next, a comparative battery BC7 was produced in the same manner as in Example 1 except that this positive electrode was used.

The types and amounts of nickel oxide powder or cobalt oxide powder added to the positive electrode active material powder in the preparation of each positive electrode of the batteries BA16 to BA30 of the present invention and the comparative batteries BC5 to BC7 are summarized in Table 2 below. Shown.

[0046]

[Table 2]

[Storage Characteristics] In the same manner as above, the storage characteristics of the batteries BA16 to BA30 of the present invention and the comparative batteries BC5 to BC7 were examined. The results are shown in FIG. In FIG. 3,
For comparison, the result of the comparative battery BC1 (transferred from FIG. 2) is also shown.

FIG. 3 shows the storage characteristics of each battery, the vertical axis shows the rate of increase in the internal resistance of the battery (%), and the horizontal axis shows the amount of nickel oxide or cobalt oxide added (mol%). It is a graph shown. However, in the batteries BA21 to BA25 of the present invention and the comparative battery BC6, the horizontal axis indicates the total amount of nickel oxide and cobalt oxide. As shown in FIG. 3, in the batteries of the present invention BA16 to BA30, the rate of increase in the internal resistance of the batteries was as low as 50% or less, whereas the comparative batteries BC5 to B30
In C7, the increase rate of the internal resistance of the battery is as high as 100% or more. From this, the increase in the internal resistance of the battery due to the decomposition of the electrolyte solution when stored at a high temperature, the oxidation number of nickel and cobalt is 3 or less, nickel oxide powder containing no lithium in the crystal and It can be seen that addition of 0.1 to 20 mol% of the cobalt oxide powder to the positive electrode active material powder significantly suppresses the addition.

Comparative Examples 8 to 10 Positive electrodes were produced in the same manner as in Examples 1 to 3, except that NiO ₂ (nickel oxidation number: 4) powder was used instead of Ni ₂ O ₃ powder. Then, in the same manner as in Example 1 except that these positive electrodes were used, the comparative battery BC8 (the amount of NiO ₂ powder added: 0.
1 mol%), BC9 (NiO ₂ powder added amount: 5 mol%), BC10 (NiO ₂ powder added amount: 10 mol%)
Was prepared.

(Comparative Examples 11 to 13) Positive electrodes were prepared in the same manner as in Examples 1 to 3, except that CoO ₂ (oxidation number of cobalt: 4) powder was used instead of Ni ₂ O ₃ powder.
Then, in the same manner as in Example 1 except that these positive electrodes were used, the comparative battery BC11 (the addition amount of the CoO ₂ powder:
0.1 mol%), BC12 (CoO ₂ powder addition amount: 5)
Mol%) and BC13 (the amount of CoO ₂ powder added: 10 mol%).

[Storage characteristics] In the same manner as above, the comparative battery B
The storage characteristics of C8 to BC13 were examined. Table 3 shows the results.

[0052]

[Table 3]

As shown in Table 3, the comparative batteries BC8 to BC8
The increase rate of the internal resistance of No. 13 is as high as 80% or more. This indicates that decomposition of the electrolytic solution cannot be sufficiently suppressed even when a nickel oxide having an oxidation number of nickel exceeding 3 or a cobalt oxide having an oxidation number of cobalt exceeding 3 is added to the positive electrode active material. .

In the above embodiments, the case where the present invention is applied to a flat type battery has been described as an example. However, the present invention is not particularly limited in the shape of the battery, and various other types such as a cylindrical type and a square type are available. It can be applied to a non-aqueous primary battery or a non-aqueous secondary battery having the shape of

The present inventors have considered that the generation of gas in the battery system is mainly due to decomposition of the non-aqueous electrolyte, but it is also possible to generate gas due to decomposition of the binder. If the improvement in storage characteristics according to the present invention is due to the suppression of the latter gas generation, the present invention is considered to be applicable not only to liquid electrolyte batteries but also to solid electrolyte batteries.

[0056]

The decomposition of the electrolytic solution during high-temperature storage is suppressed by adding nickel oxide and / or cobalt oxide to the positive electrode active material. Excellent.

[Brief description of the drawings]

FIG. 1 is a sectional view of a flat type battery of the present invention.

FIG. 2 is a graph showing storage characteristics of a battery of the present invention and a comparative battery.

FIG. 3 is a graph showing storage characteristics of a battery of the present invention and a comparative battery.

[Explanation of symbols]

 BA1 Battery of the present invention 1 Positive electrode 2 Negative electrode 3 Separator

──────────────────────────────────────────────────の Continuing on the front page (72) Koji Nishio, inventor 2-5-5, Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toshihiko Saito 2-5-2, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (56) References JP-A-62-264560 (JP, A) JP-A-63-211565 (JP, A) JP-A-2-12768 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01M 4/02 H01M 10/40 H01M 4/36-4/62

Claims (3)

(57) [Claims] A negative electrode comprising lithium as a negative electrode active material;
Li _X Ni _1-Y M _Y O _Z (where 0 <X <1.3, 0 ≦
Y ≦ 1, 1.8 <Z <2.2, and M is cobalt or two or more transition metals containing cobalt. A) a positive electrode comprising a lithium-transition metal composite oxide as a positive electrode active material, wherein the oxidation number of nickel with respect to the positive electrode active material is 3 or less and lithium is not contained in the crystal. A non-aqueous battery comprising a nickel oxide and / or cobalt having an oxidation number of 3 or less, and 0.1 to 20 mol% of a cobalt oxide containing no lithium in a crystal. 2. The non-aqueous battery according to claim 1, wherein said nickel oxide is NiO. 3. The non-aqueous battery according to claim 1, wherein said cobalt oxide is Co ₃ O ₄ .