JP3349379B2 - Non-aqueous electrolyte secondary 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 electrolyte secondary battery including a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte. In a non-aqueous electrolyte secondary battery housed in a battery can in a wound state, when charging and discharging are repeatedly performed, the wound electrode is deformed as described above, and the cycle characteristics are reduced. The present invention relates to a non-aqueous electrolyte secondary battery having a low battery capacity and a sufficient battery capacity.

[0002]

2. Description of the Related Art In recent years, as one of new high-power, high-energy-density secondary batteries, a high electromotive force utilizing oxidation and reduction of lithium using a positive electrode and a negative electrode capable of inserting and extracting lithium ions. Non-aqueous electrolyte secondary batteries have come to be used.

Here, in such a non-aqueous electrolyte secondary battery, generally, the above-described positive electrode and negative electrode are spirally wound through a separator, and the thus wound electrode is fixed with an adhesive tape. This was housed in a battery can.

However, when charging and discharging are repeatedly performed in a non-aqueous electrolyte secondary battery in which the wound electrode is fixed with an adhesive tape and accommodated in a battery can, absorption and release of lithium ions are caused. The electrode wound up as described above is deformed, and the adhesive tape fixing the electrode is peeled off, so that charging and discharging cannot be performed well, and there is a problem that the cycle characteristics gradually decrease.

Therefore, conventionally, Japanese Patent Laid-Open Publication No.
As shown in Japanese Patent No. 2647, a resin layer that expands when the electrolyte is impregnated is provided on the inner surface of the battery can in which the electrode wound as described above is accommodated, and the electrode wound as described above is deformed by charging and discharging. This has been proposed in which this is suppressed by this resin layer.

However, when a resin layer not involved in charge / discharge is provided in the battery can, there is a problem that the battery capacity is reduced by the amount of the resin layer.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte. The above positive electrode and negative electrode are wound and accommodated in a battery can. It is an object of the present invention to solve the above-described problem in the nonaqueous electrolyte secondary battery, and the electrode housed in the battery can with the positive electrode and the negative electrode wound as described above is deformed by charging and discharging. The battery has sufficient battery capacity and excellent charge / discharge cycle characteristics without deterioration in cycle characteristics, and without reduction in battery capacity as in the case where a resin layer is provided on the inner surface of a battery can. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery showing the following.

[0008]

In order to solve the above-mentioned problems, a nonaqueous electrolyte secondary battery according to the present invention comprises a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a nonaqueous electrolyte. In a nonaqueous electrolyte secondary battery in which a positive electrode and a negative electrode are wound and accommodated in a battery can, the negative electrode is connected to the battery can when the negative electrode is connected to the battery can.
The surface contains a negative electrode material that can absorb and release lithium ions.
When the positive electrode is connected to the
Positive electrode capable of inserting and extracting lithium ions on the inner surface of a pond can
A layer containing a material is provided. Also,
In the non-aqueous electrolyte secondary battery according to
Provide a copper plating layer on the inner surface of the battery
Absorption and release of the above lithium ions on the copper plating layer
A layer containing a negative electrode material capable of
You.

Here, when a negative electrode is connected to a battery can as in the non-aqueous electrolyte secondary battery of the present invention, the battery is not charged.
A negative electrode that can store and release lithium ions on the inner surface of a pond can
When the positive electrode is connected to a layer containing materials or a battery can
Can absorb and release lithium ions on the inner surface of the battery can.
When a layer containing a positive electrode material is provided, deformation of the electrode housed in the battery can in the state where the positive electrode and the negative electrode are wound as described above due to charging and discharging is suppressed by the above-described layer. Deterioration of the cycle characteristics in the electrolyte secondary battery is reduced, and lithium ions are absorbed and released also in the above-mentioned layers, exhibiting the same function as the electrodes, and when the resin layer is provided on the inner surface of the battery can. As described above, a sufficient battery capacity can be obtained without a decrease in the battery capacity.

In the nonaqueous electrolyte secondary battery according to the present invention, when a layer containing a negative electrode material capable of absorbing and releasing lithium ions is provided on the inner surface of the battery can connected to the negative electrode as described above, If a copper plating layer is provided on the inner surface of the can, and the above layer is provided on the copper plating layer, electricity easily flows through the copper plating layer, and the capacity of the nonaqueous electrolyte secondary battery is further increased. improves.

Here, in the nonaqueous electrolyte secondary battery according to the present invention, the positive electrode material used for the positive electrode includes:
A known positive electrode material that has been conventionally used can be used, and a lithium transition metal composite containing at least one metal compound capable of inserting and extracting lithium ions, for example, manganese, cobalt, nickel, iron, vanadium, niobium, or the like. An oxide or the like can be used.

In the non-aqueous electrolyte secondary battery according to the present invention, as the negative electrode material used for the negative electrode, a conventionally known negative electrode material can be used. In addition, a carbon material such as graphite, coke, and a fired organic material can be used.

Further, in the non-aqueous electrolyte secondary battery according to the present invention, as the above-mentioned non-aqueous electrolyte, a conventionally known non-aqueous electrolyte and the like can be used.
As the solvent in the non-aqueous electrolyte, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, sulfolane, dimethyl sulfolane, 3-methyl-
1,3-oxazolidin-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane , Tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, methyl acetate, ethyl acetate, and other organic solvents can be used alone or in combination of two or more.

In the non-aqueous electrolyte, a solute generally used conventionally can be used as the solute to be dissolved in the above-mentioned solvent. For example, LiPF ₆ ,
LiCF ₃ SO ₃ , LiBF ₄ , LiAsF ₆ , LiN
(CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _{3 and the} like can be used.

[0015]

EXAMPLES Hereinafter, the nonaqueous electrolyte secondary battery according to the present invention will be specifically described with reference to examples, and the charge / discharge cycle characteristics and battery capacity of the nonaqueous electrolyte secondary battery according to the examples of the present invention will be described. It will be clarified that Comparative Example 1 is superior in terms of Comparative Example. The non-aqueous electrolyte secondary battery according to the present invention is not limited to those shown in the following examples, but can be implemented by appropriately changing the scope of the invention without changing its gist.

Example 1 In Example 1, a positive electrode, a negative electrode, and a non-aqueous electrolyte prepared as described below were used, and a single-size cylindrical type as shown in FIGS. 1 and 2 was used. A non-aqueous electrolyte secondary battery was manufactured.

[Preparation of Positive Electrode] To prepare a positive electrode, LiCoO ₂ powder was used as a positive electrode material.
The artificial graphite and the polyfluoride are added to the LiCoO ₂ powder so that the CoO ₂ powder, the artificial graphite as the conductive agent, and the polyvinylidene fluoride as the binder have a weight ratio of 90: 5: 5. A binder solution in which vinylidene was dissolved at 5% by weight in N-methyl-2-pyrrolidone (NMP) was added, and these were kneaded to prepare a positive electrode slurry.

Then, this positive electrode slurry was applied to both surfaces of a positive electrode current collector composed of aluminum foil by a doctor blade method, and this was vacuum-dried at 150 ° C. for 2 hours to produce a positive electrode.

[Preparation of Negative Electrode] In preparing the negative electrode, the surface distance d on the (002) plane was used as the negative electrode material.
₀₀₂ is 3.35% of natural graphite, and polyvinylidene fluoride is added to NMP in an amount of 5% by weight to natural graphite so that the weight ratio of the natural graphite to polyvinylidene fluoride as a binder is 95: 5. % Dissolved binder solution,
These were kneaded to prepare a negative electrode slurry.

Then, this negative electrode slurry was applied to both surfaces of a negative electrode current collector made of copper foil by a doctor blade method, and this was vacuum-dried at 150 ° C. for 2 hours to produce a negative electrode.

[Preparation of Non-Aqueous Electrolyte] In preparing the non-aqueous electrolyte, a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used as the solvent. 1 LiPF ₆
A non-aqueous electrolyte was prepared by dissolving at a mol / l ratio.

[Preparation of Battery] In preparing a battery, an iron battery can having an inner surface plated with nickel was used, and as shown in FIGS. The negative electrode slurry prepared in the preparation of the negative electrode was applied so as to have a thickness of 30 to 80 μm, and dried at 120 ° C. for 1 hour to occlude and release the same lithium ions on the inner surface of the battery can 4 as the negative electrode. A layer 9 containing natural graphite capable of being provided was provided.

Then, the positive electrode 1 produced as described above
A lithium ion permeable polypropylene microporous membrane is interposed as a separator 3 between the anode and the negative electrode 2, and these are spirally wound and accommodated in the battery can 4. The above non-aqueous electrolyte is injected and sealed, and the positive electrode 1 is connected to the positive electrode lid 6 via the positive electrode lead 5, and the negative electrode 2 is connected to the battery can 4 via the negative electrode lead 7. And the positive electrode cover 6 were electrically separated by an insulating packing 8.

(Comparative Example 1) In Comparative Example 1, the negative electrode slurry was not applied to the inner surface of the battery can in the production of the battery in Example 1 described above.
A non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 except that no layer containing natural graphite that could be released was provided.

(Examples 2 to 4) In Examples 2 to 4, the negative electrode material used in the production of the negative electrode in Example 1 was changed, and in Example 2, d ₀₀₂ was 3.
In Example 3, d ₀₀₂ was 3.
The negative electrode slurry was adjusted using petroleum coke that became 47 ° and acetylene black with d ₀₀₂ that became 3.48 ° in Example 4, and each negative electrode was prepared using these negative electrode slurries. The slurry was applied to the inner surface of each nickel-plated battery can 4 to a thickness of 30 to 80 μm in the same manner as in Example 1 above, and dried at 120 ° C. for 1 hour. On the inner surface of the can 4, a layer 9 containing each negative electrode material capable of inserting and extracting lithium ions is provided.
Each non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 described above.

(Comparative Examples 2 to 4) In Comparative Examples 2 to 4, the negative electrode material used for the negative electrode was changed from that of Comparative Example 1 described above, and in Comparative Example 2, the same artificial graphite as that of Example 2 was used. In Comparative Example 3, the same petroleum coke as in Example 3 was used, and in Comparative Example 4, the same acetylene black as in Example 4 was used. Otherwise, the non-aqueous electrolyte was used in the same manner as in Comparative Example 1. A secondary battery was manufactured, and a layer containing a negative electrode material capable of inserting and extracting lithium ions was not provided on the inner surface of the battery can.

Embodiment 5 In this embodiment 5, in the manufacture of the battery in the above-mentioned embodiment 1, an iron battery can whose inner surface is plated with copper is used, in the same manner as in the above-mentioned embodiment 1. A negative electrode slurry using natural graphite was applied to the inner surface of the copper-plated battery can 4, and this was heated to 120 ° C.
For 1 hour to provide a layer 9 containing natural graphite capable of occluding and releasing lithium ions.
A non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 described above.

(Comparative Example 5) In Comparative Example 5, instead of providing a layer containing natural graphite capable of occluding and releasing lithium ions on the inner surface of the battery can in the production of the battery in Example 1 described above, About 50μm on the inner surface of this battery can
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that a resin layer having a thickness of was provided.

Example 6 In Example 6, a negative electrode current collector made of copper foil was used as a negative electrode material in the preparation of the negative electrode in Example 1 above, using a lithium metal foil as the negative electrode material. Attached to both sides and thickness is about 14
A negative electrode having a thickness of 0 μm was prepared, and the above-described metal lithium foil was attached to the inner surface of the nickel-plated battery can 4. A metal lithium layer 9 capable of inserting and extracting lithium ions was formed on the inner surface of the battery can 4. A non-aqueous electrolyte secondary battery was fabricated in the same manner as in Example 1 except for the above.

(Comparative Example 6) In Comparative Example 6, as in the case of the above-described Example 6, a negative electrode made of a metal lithium foil was used as a negative electrode material, while a metal A non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 6 except that the lithium foil was not attached.

Next, the first embodiment manufactured as described above was used.
-6 and each of the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 6 were charged at a charging current of 200 mA to a charging end voltage of 4.2 V, and then discharged at a discharging current of 200 mA to a discharging end voltage of 2.75 V. The initial capacity of each non-aqueous electrolyte secondary battery was measured, and the results are shown in Table 1 below.
In addition, the charge / discharge was repeated by setting the above charge / discharge as one cycle, and the change in the discharge capacity with the increase in the number of cycles was examined. The result is shown in FIG.

[0032]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 4 in which the layer 9 of the same material as the negative electrode was provided on the inner surface of the battery can 4.
Each of the nonaqueous electrolyte secondary batteries of Comparative Example 6 and Comparative Examples 1 to 4 and 6 in which such a layer was not provided, and those of Comparative Example 5 in which a resin layer was provided on the inner surface of a battery can. The initial capacity was higher than that of the nonaqueous electrolyte secondary battery, and a nonaqueous electrolyte secondary battery having a high battery capacity was obtained. In particular, in the nonaqueous electrolyte secondary battery of Example 5 in which the copper plating layer was provided on the inner surface of the battery can 4, electricity smoothly flowed through the copper plating layer, and the battery capacity was further improved.

As is clear from the results of FIG. 3, each of the nonaqueous electrolyte secondary batteries of Examples 1 to 6 in which the layer 9 of the same material as the negative electrode was provided on the inner surface of the battery can 4 as described above, Compared with the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 4 and 6 in which such a layer was not provided, a decrease in capacity with an increase in the number of cycles was reduced.

Example 7 In Example 7, a positive electrode, a negative electrode and a non-aqueous electrolyte were prepared in the same manner as in Example 1 described above, and a battery can was used as shown in FIG. An aluminum battery can 4 having a square shape was used.

Here, in Example 7, when producing a non-aqueous electrolyte secondary battery having a square shape, as shown in FIG. The positive electrode slurry prepared in the above was applied so as to have a thickness of 30 to 80 μm, and dried at 120 ° C. for 1 hour. LiCoO ₂ capable of absorbing and releasing the same lithium ions as the positive electrode was formed on the inner surface of the battery can 4. The layer 9 containing the metal was provided.

Then, a lithium ion permeable polypropylene microporous membrane is interposed as a separator 3 between the positive electrode 1 and the negative electrode 2 produced in the same manner as in the above-mentioned Example 1, and these are square-shaped. After being wound so as to correspond to the battery can 4 and housed in the battery can 4, the battery can 4
The above-mentioned non-aqueous electrolyte was injected into the inside and sealed, so that the positive electrode 1 was connected to a positive electrode terminal (not shown) and the negative electrode 2 was connected to a negative electrode terminal (not shown).

(Comparative Example 7) In Comparative Example 7, in the manufacture of the battery in Example 7 described above, the positive electrode slurry was not applied to the inner surface of the battery can, and the lithium ions were absorbed and absorbed.
A non-aqueous electrolyte secondary battery was fabricated in the same manner as in Example 7 except that no layer containing LiCoO ₂ capable of being released was provided.

(Examples 8 to 11) These Examples 8 to 1
In Example 1, the cathode material used in the production of the cathode in Example 1 was changed, and in Example 8, LiNi was used.
The O ₂ powder, a LiMn ₂ O ₄ powder in Example 9, the LiNi _0.5 Co _0.5 O ₂ powder in Example 10, Example 1
In No. 1, positive electrode slurries were prepared using LiV ₂ O ₅ powders, and each positive electrode was prepared using these positive electrode slurries. Each positive electrode slurry was formed into a square shape in the same manner as in Example 7 above. It is applied to the inner surface of the aluminum battery can 4 having a thickness of 30 to 80 μm, and dried at 120 ° C. for 1 hour to occlude the same lithium ions as the respective positive electrodes on the inner surface of the battery can 4. A layer 9 containing a positive electrode material capable of being released was provided, and each nonaqueous electrolyte secondary battery was manufactured in the same manner as in Example 7 described above.

(Comparative Examples 8 to 11) These Comparative Examples 8 to 1
In Comparative Example 1, the positive electrode material used for the positive electrode was changed from that in Comparative Example 7, and in Comparative Example 8, the same LiN was used as in Example 8.
iO ₂ powder, the same LiMn ₂ Example 9 Comparative Example 9
The O ₄ powder was used in Comparative Example 10 in the same LiNi as in Example 10.
_{For the 0.5} Co _0.5 O ₂ powder, the same LiV ₂ O ₅ powder as in Example 11 was used in Comparative Example 11, and the other non-aqueous electrolyte secondary batteries were otherwise the same as in Comparative Example 7. And a layer containing a positive electrode material capable of inserting and extracting lithium ions was not provided on the inner surface of the battery can.

Next, the seventh embodiment manufactured as described above was used.
Each of the non-aqueous electrolyte secondary batteries of Comparative Examples 7 to 11 and Comparative Examples 7 to 11 also has a charging current of 200
The battery was charged to a final charge voltage of 4.2 V at mA, then discharged to a final discharge voltage of 2.75 V at a discharge current of 200 mA, and the initial capacity of each non-aqueous electrolyte secondary battery was measured. 2 is shown.

[0042]

[Table 2]

As is apparent from the results, the nonaqueous electrolyte secondary batteries of Examples 7 to 11 in which the layer 9 of the same material as the positive electrode was provided on the inner surface of the battery can 4 also have the negative electrode on the inner surface of the battery can 4. Similar to the non-aqueous electrolyte secondary batteries of Examples 1 to 6 provided with the layer 9 of the same material, as compared with the non-aqueous electrolyte secondary batteries of Comparative Examples 7 to 11 not provided with the layer of such material. Thus, a non-aqueous electrolyte secondary battery having a high initial capacity and a high battery capacity can be obtained. Water electrolyte secondary batteries are
Compared with the non-aqueous electrolyte secondary batteries of Comparative Examples 7 to 11 in which such a layer was not provided, the decrease in capacity due to the increase in the number of cycles was smaller.

[0044]

As described in detail above, in the nonaqueous electrolyte secondary battery according to the present invention, when the positive electrode and the negative electrode capable of inserting and extracting lithium ions are accommodated in a battery can in a wound state, When the negative electrode is connected to the battery can
Can absorb and release lithium ions on the inner surface of the battery can.
The positive electrode is connected to a layer containing a functional negative electrode material or a battery can.
When the battery can be stored, lithium ions are stored on the inner surface of the battery can.
Since a layer containing a positive electrode material capable of being released is provided, the above-mentioned layer suppresses deformation of the electrode wound around the positive electrode and the negative electrode due to charge and discharge, and also stores and absorbs lithium ions in this layer. Release is performed, and deterioration of cycle characteristics is reduced, and as in the case where a resin layer is provided on the inner surface of the battery can, the battery capacity is not reduced, and while having sufficient battery capacity,
A non-aqueous electrolyte secondary battery showing excellent charge / discharge cycle characteristics was obtained.

The non-aqueous electrolyte secondary battery according to the present invention
In the pond, the inner surface of the battery can connected to the negative electrode
An anode layer is provided on the copper plating layer.
If you try to provide a layer containing, through the copper plating layer
Electricity flows easily, and this non-aqueous electrolyte secondary battery
Capacity has been further improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the internal structure of each of the nonaqueous electrolyte secondary batteries of Examples 1 to 6 of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of each of the non-aqueous electrolyte secondary batteries of Examples 1 to 6 of the present invention.

FIG. 3 is a diagram showing the relationship between the number of cycles and the discharge capacity when charge and discharge are repeatedly performed for each of the nonaqueous electrolyte secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 6 of the present invention. It is.

FIG. 4 is a cross-sectional view showing the internal structure of each of the non-aqueous electrolyte secondary batteries of Examples 7 to 11 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 4 Battery can 9 Layer containing material which can occlude and release lithium ions

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Noma 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (56) References JP-A-5-182647 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40 H01M 2/02 H01M 4 / 64

Claims (2)

(57) [Claims] 1. A non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte, wherein the positive electrode and the negative electrode are wound and accommodated in a battery can. When the negative electrode is connected to the electrode can,
A negative electrode that can store and release lithium ions on the inner surface of a pond can
When the positive electrode is connected to a layer containing materials or a battery can
Can store and release lithium ions inside the battery can
A non-aqueous electrolyte secondary battery provided with a layer containing a positive electrode material . 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the inner surface of the battery can to which the negative electrode is connected is made of copper.
A copper layer is provided, and the above-described lithium ion
A layer containing a negative electrode material capable of occluding and releasing ON is provided.
The non-aqueous electrolyte secondary battery according to claim 1, wherein