JP2002237292A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery reducing the manufacturing failure rate of the battery and having an excellent high-rate discharge characteristic. SOLUTION: This nonaqueous electrolyte secondary battery is provided with a power generating element formed by piling, winding or laminating a positive electrode plate, a separator, a negative electrode plate and a separator in this order, and only the edge part of at least one electrode plate out of the positive and negative electrode plates is projected from one end face of the power generating element. In this case, through holes or/and cutout parts are formed in a mixture unapplied part provided at a base material at the projected edge part of the electrode plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight has been adopted as a built-in battery.

A typical battery that meets such requirements is:
Using a lithium active material capable of reversibly occluding and releasing lithium as a negative electrode active material, and a lithium active material capable of reversibly occluding and releasing lithium,
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as iClO ₄ or LiPF ₆ is dissolved as an electrolyte. In particular, a carbonaceous material is used as the negative electrode active material, and LiCoO ₂ , LiNiO ₂ or Li
A lithium ion battery using Mn ₂ O ₄ or the like is suitable for practical use because of its excellent charge / discharge cycle life.

In each of the positive electrode plate and the negative electrode plate of these non-aqueous electrolyte secondary batteries, a mixture containing an active material, a conductive material and a binder is applied to a thin metal substrate and dried to form a thin sheet or sheet. A foil-shaped power generation element is sequentially laminated or spirally wound via a separator. And this power generation element, stainless steel, nickel-plated iron,
Alternatively, the battery is housed in a battery container made of a metal can made of aluminum or the like, and after the electrolyte is injected, the battery is assembled by hermetically sealing with a lid plate.

[0005] In a small non-aqueous electrolyte secondary battery having a capacity of 1 Ah or less used for a portable device or a computer, since the battery is relatively small and it is not necessary to discharge at a current greater than 3 hours, the terminal of the electrode is The method of collecting electricity only from the department is used.

On the other hand, hybrid electric vehicles using both motors and engines have attracted attention.
The development of non-aqueous electrolyte secondary batteries for this purpose has been actively performed. When a nonaqueous electrolyte secondary battery is put into practical use as a large-capacity battery such as a battery for a hybrid electric vehicle, the battery is required to have good high-rate discharge characteristics and a large output.

Therefore, in a large-capacity battery for a hybrid electric vehicle or the like, since the electrode area is large and it is necessary to charge and discharge with an extremely large current such as a rate of 5 hours or more, the entire edge of the electrode plate is required. In order to be able to collect current from the electrode plate, a portion where the mixture is not applied is provided on the base material at the edge of the electrode plate, and the edge of one electrode plate is protruded from the edge of the other electrode plate, and the After winding the electrode plate and the separator in a shape, a method of collecting current from the base material at the edge of the electrode plate corresponding to the end face of the power generating element has been used.

[0008]

In a conventional non-aqueous electrolyte secondary battery, when manufacturing an electrode plate, after applying a mixture and performing a drying treatment, the adhesiveness between the mixture and the mixture is determined. Pressing is performed to increase the adhesion to a base material as a current collector. At this time, as the gap between the mixture is compressed, the base material of the electrode plate is also compressed, and its area is extended and increased. On the other hand, pressure is not directly applied to the base material at the edge of the electrode plate where the mixture is not applied. As a result, a difference in elongation occurs between the base material portion of the electrode plate where the mixture is applied and the base material of the edge portion of the electrode plate where the mixture is not applied, and the electrode is distorted. There was a problem.

[0009] As a result, when the separator and the electrode plate are wound, a winding deviation occurs to cause an insulation failure or a wrinkle to form a gap between the electrode and the separator, and the internal resistance of the battery increases. Problem had arisen. The same occurs in the case of a stacked power generation element.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a non-aqueous electrolyte battery which has a reduced defective battery production rate and has excellent high-rate discharge characteristics.

[0011]

According to a first aspect of the present invention, there is provided a power generating element in which a positive electrode plate, a separator, a negative electrode plate, and a separator are sequentially stacked, wound or laminated, and one end face of the power generating element. In a non-aqueous electrolyte secondary battery in which only the edge portion of at least one of the positive and negative electrode plates is protruded, the mixture-uncoated portion provided on the base material of the protruded edge portion of the electrode plate, A through hole and / or a notch is formed.

According to the first aspect of the present invention, when the electrode plate is subjected to press working, the difference in elongation between the base material of the mixture-applied portion and the base material of the uncoated portion is reduced. Then, by reducing the distortion of the electrode, it is possible to reduce the rate of occurrence of slippage or wrinkles when winding or laminating the electrode and the separator, and it is possible to densely wind or laminate the electrode and the separator. Thus, a non-aqueous electrolyte secondary battery having excellent high-rate discharge characteristics can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The non-aqueous electrolyte secondary battery of the present invention
A positive electrode plate, a separator, a negative electrode plate, and a power generating element formed by sequentially stacking, winding or laminating the separator, and an edge of at least one of the positive and negative electrode plates from one end surface of the power generating element. Only one is projected. A through-hole or / and a notch is formed in the mixture-unapplied portion provided on the base material at the edge of the protruding electrode plate.

An embodiment of the present invention will be described with reference to the drawings, taking a non-aqueous electrolyte secondary battery provided with a long cylindrical wound power generating element using a strip-shaped electrode plate as an example.

FIG. 1 is a plan view of a positive electrode plate used in a non-aqueous electrolyte secondary battery according to the present invention, and FIG. 8 is a plan view of a positive electrode plate used in a conventional non-aqueous electrolyte secondary battery. 1 and 8, 1 is a positive electrode plate, 2 is a substrate, 3 is a mixture layer,
Reference numeral 4 denotes a portion where the mixture layer is not applied, and reference numeral 5 denotes a through hole. The shape of the negative electrode plate is almost the same as that of the positive electrode plate.

In the positive electrode plate used in the non-aqueous electrolyte secondary battery of the present invention, as shown in FIG. FIGS. 5 to 7 show plan views of other examples of the positive electrode plate used in the nonaqueous electrolyte secondary battery of the present invention. In FIGS. 5 to 7, symbols 3 and 4 indicate the same as in FIG. 1, 14 in FIG. 5 is a square through hole, 15 in FIG. 6 is a rectangular cutout, and 16 in FIG.
Is a U-shaped notch.

In the present invention, the width of the uncoated portion provided on the base material at the edge portion of the electrode plate may be appropriately selected according to the width of the electrode plate. Is preferably in the range of 0.5 mm or more and 10 cm or less.

The shapes of the through holes or notches formed in the uncoated portion 4 of the base material 2 of the positive electrode plate used in the nonaqueous electrolyte secondary battery of the present invention are shown in FIGS. In addition to the shapes shown in the above, any shape such as a polygon or an ellipse can be used as the through hole, and a V-shaped, semicircular or semi-elliptical shape can be used as the cutout. Also, in one electrode plate, only a through hole may be formed,
Only the notch may be formed, or the through-hole and the notch may be simultaneously formed.

The number of through holes and notches formed in one electrode plate may be appropriately selected according to the number of turns of the power generating element. However, if the number is too small, the effect of the present invention is poor. If the amount is too large, the mechanical strength of the mixture layer uncoated portion 4 of the base material 2 becomes weak. Therefore, the ratio of the total area of the through holes or / and cutouts to the area of the mixture layer uncoated portion is 10%.
It is preferable to set it to 40% or less.

In the electrode manufacturing process, when a through hole or / and a notch is formed in the portion of the electrode base material where the mixture layer is not applied, the mixture may be applied before the mixture is applied. It may be after the application. In addition, a through hole or / and a notch may be formed at the same time when the electrode is pressed.

Both the positive electrode plate and the negative electrode plate, as shown in FIG. 1, show the appearance of a long cylindrical wound type power generating element using an electrode plate having a circular through hole in a portion of the base material where the mixture layer is not applied. As shown in FIG. In FIG. 2, reference numeral 6 denotes a positive electrode plate, 7 denotes a negative electrode plate, 8 denotes a separator, 9 denotes a winding core, X denotes an uncoated portion of the edge portion of the positive electrode plate, and Y denotes a non-mixed portion of the edge portion of the negative electrode plate. This is the application section. As shown in FIG. 2, the power generating element includes a positive electrode plate 6, a separator 8,
The negative electrode plate 7 and the separator 8 are sequentially superimposed to form a winding core 9.
It is wound around. From the upper end face of the power generating element, only the mixture non-applied portion X at the edge of the positive electrode plate protrudes, and from the lower end face of the power generating element, only the mixture non-applied part Y at the edge of the negative electrode plate. It is protruding.

In FIG. 2, the uncoated portion of the edge of the positive electrode plate protrudes from the upper end face of the power generating element, while the uncoated portion of the edge of the negative electrode plate is protruded from the lower end face of the power generating element. However, in some cases, only the uncoated portion of the edge of one of the positive electrode plate and the negative electrode plate may protrude from one end surface of the power generation element.

In the present invention, a through-hole may or may not be provided in the portion of the base material of the electrode plate where the mixture layer is applied, but in order to simplify the manufacturing process, a through-hole is provided. It is preferable not to have them.

Further, as the shape of the power generating element, a cylindrical wound type or a laminated type can be used in addition to the long cylindrical wound type.

Further, as the positive electrode active material used in the nonaqueous electrolyte secondary battery of the present invention, as the inorganic compound, a composition formula Li _x MO ₂ or Li _y M ₂ O ₄ (where M is a transition metal, Composite oxides, oxides having tunnel-like vacancies represented by 0 ≦ x ≦ 1, 0 ≦ y ≦ 2), metal chalcogenides having a layered structure, and the like can be used. As specific examples, LiCoO ₂ , LiNiO ₂ , LiMn
₂ O ₄ , Li ₂ Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V
₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , TiO ₂ , NiOOH,
FeOOH and the like. Examples of the organic compound include a conductive organic polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

Further, lithium as the negative electrode active material of the present invention
As a substance that can store and release lithium or lithium ions
Is a carbonaceous material such as MCMB, flaky graphite, massive graphite,
Li ₅(Li₃N), such as lithium nitride, metallic lithium,
Al, Si, Pb, Sn, Zn, Cd, etc. and lithium
Alloy, LiFe₂O₃, WO₂, MoO₂Transition metals such as
The oxides can be used alone or mixed
You. Among these negative electrode active materials, non-graphitizable carbon is used.
Is preferred. The reason is that non-graphitizable carbon is
This is because the distance is large and the volume change due to charging and discharging is small.
You. As an electrolyte solvent of the non-aqueous electrolyte secondary battery of the present invention
Means ethylene carbonate, propylene carbonate, etc.
Cyclic carbonate, dimethyl carbonate or diethyl
Chain carbonic acid such as carbonate and methyl ethyl carbonate
Ester, γ-butyrolactone, sulfolane, dimethyl
Sulfoxide, acetonitrile, dimethylformami
Dimethylacetamide, 1,2-dimethoxyethane
1,2-diethoxyethane, tetrahydrofuran,
2-methyltetrahydrofuran, dioxolan, methyl
Use a polar solvent such as acetate, or a mixture of these.
Can be used. Lithium dissolved in organic solvents
As the salt, LiPF₆, LiBF₄, LiAs
F₆, LiCF₃CO₂, LiCF₃SO₃, LiN
(SO₂CF₃)₂, LiN (SO₂CF₂C
F₃)₂, LiN (COCF₃)₂And LiN (CO
CF₂CF₃)₂Or a mixture of these
Good. In addition, polyethylene or polypropylene
Insulating polyolefin microporous membrane such as pyrene, polymer
Solid electrolyte, polymer solid electrolyte containing electrolyte solution
A solid electrolyte or the like can also be used. In addition, an insulating microporous film
A solid polymer electrolyte or the like may be used in combination. Sa
Furthermore, as a solid polymer electrolyte, a porous solid polymer electrolyte
When a membrane is used, the electrolyte contained in the polymer and the fine
The electrolyte to be contained in the pores may be different. Ma
In addition, the porous polymer solid electrolyte membrane is
Surface and the active material itself.
I will.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on preferred embodiments.

Example 1 The positive electrode plate had the same shape as that shown in FIG. As a positive electrode active material, lithium carbonate 0.1.
LiCoO ₂ obtained by mixing 5 mol and 1 mol of cobalt carbonate and firing at 900 ° C. in the air was used. This L
91% by weight of iCoO ₂ and graphite 6 as a conductive agent
% By weight, and polyvinylidene fluoride (PVd) as a binder.
F) 3% by weight was mixed to obtain a positive electrode mixture. N-methyl-2-pyrrolidone (NMP) was added as a solvent to this positive electrode mixture, mixed and dispersed to form a slurry.

A 20 μm-thick strip-shaped aluminum foil was used as the substrate 2 of the positive electrode plate, and the positive electrode mixture slurry was uniformly applied to the substrate 2. At this time, an uncoated portion 4 having a width of 10 mm was provided at one edge of the long side of the positive electrode plate.

After drying the positive electrode plate, the thickness was adjusted using a roll press. On one roll of the roll press machine, a convex portion having a diameter of 8 mm is provided, and on the other roll, concave portions for receiving the convex portion are provided at intervals of 20 mm along the outer periphery of the roll. 20 m on the metal foil part where the mixture layer is not applied (the part 4 where the mixture layer is not applied)
Through holes 5 having a diameter of 8 mm were continuously formed at intervals of m.

The shape of the negative electrode plate was the same as that shown in FIG. As the negative electrode active material, a graphite powder capable of doping / dedoping lithium was used. Graphite powder 90
Wt% and 10 wt% of PVdF as a binder were mixed to prepare a negative electrode mixture. NMP was added as a solvent to this negative electrode mixture and kneaded to form a slurry. A 20 μm-thick strip-shaped copper foil was used as a base material of the negative electrode plate, and a negative electrode mixture slurry was uniformly applied to the base material. As in the case of the positive electrode, a 10 mm-wide unmixed layer uncoated portion was also provided on one edge of this electrode.

After drying the negative electrode, the thickness was adjusted using the above-mentioned roll press machine to prepare a strip-shaped negative electrode. At this time, similarly to the positive electrode on the negative electrode, the metal foil portion where the mixture layer was not applied (the portion where the mixture layer was not applied) had a diameter of 8 m at intervals of 20 mm.
m through holes were continuously formed.

The external appearance of the long cylindrical wound power generation element manufactured using the positive electrode plate and the negative electrode plate manufactured as described above is the same as that shown in FIG. The positive electrode plate 6, the separator 8, the negative electrode plate 7, and the separator 8 are overlapped and wound around the core 9 so that the edge of the electrode plate protrudes from the edge of the other electrode plate to generate power. Elements. Here, a microporous film made of polyethylene was used as the separator 8, and a pipe made of polyimide was used as the winding core 9.

FIG. 3 shows the appearance of the obtained power generating element.
FIG. 4 shows an appearance in which a current collector is attached to the power generating element. FIG.
4 and 9, 9 is a winding core, 10 is a tape, 11
Denotes a power generating element, 12 denotes a positive electrode current collector, and 13 denotes a negative electrode current collector.

The outer periphery of the cylindrical power generating element was fixed with tape 10 and crushed to obtain a power generating element having an oval cross section as shown in FIG. Then, as shown in FIG. 4, the positive electrode current collector 12 is attached to the linear portion at the upper edge of the power generating element 11, and the negative electrode current collector 1 is attached to the linear portion at the lower edge.
3, and the edge of the electrode was welded to the positive and negative electrode current collectors using ultrasonic welding.

This power generating element is placed in an oblong battery container (50
(mm × 130 mm × height 210 mm) and sealed. The positive electrode current collector and the negative electrode current collector were respectively connected to the positive electrode terminal and the negative electrode terminal mounted on the battery cover, and the battery cover was welded to the battery case. Next, into this battery container, an electrolytic solution obtained by dissolving 1 mol / l lithium hexafluorophosphate (LiPF ₆ ) in a 1: 1 (volume ratio) mixed solution of ethylene carbonate and dimethyl carbonate was injected under reduced pressure. The capacity of this battery was 3.5 Ah.

Example 2 Same as Example 1 except that the shape of the through-holes formed in the edge portions of the positive electrode plate and the negative electrode plate was a square of 8 mm × 8 mm as shown in FIG. Thus, the battery of Example 2 was produced.

[Example 3] An opening 8 mm and a depth 8 as shown in FIG.
A battery of Example 3 was produced in the same manner as in Example 1, except that a rectangular notch of mm was formed.

Example 4 An opening 8 mm and a depth 8 as shown in FIG.
A battery of Example 4 was produced in the same manner as in Example 1 except that a U-shaped notch of mm was formed.

Example 5 The same as Example 1 except that the shape of the through-holes formed at the edges of the positive electrode plate and the negative electrode plate was circular as shown in FIG. 1 and the diameter was 5 mm. Thus, a battery of Example 5 was produced.

[Example 6] The through hole formed in the edge portion of the positive electrode plate and the negative electrode plate was formed as a square as shown in FIG. 5 and the size was set to 4 mm × 4 mm. In the same manner as in Example 1, a battery of Example 6 was produced.

Comparative Example 1 A comparative example was made in the same manner as in Example 1 except that the electrode plate shown in FIG. 8 was used without forming a through-hole or a notch at the edges of the positive electrode plate and the negative electrode plate. Battery No. 1 was produced.

Table 1 shows the ratio of the total area of the through holes and / or the notches to the area of the mixture layer uncoated portion in the batteries of Examples 1 to 6 and Comparative Example 1.

[0044]

[Table 1]

Each of the batteries of Examples 1 to 6 and Comparative Example 1 was manufactured by 100 pieces. At this time, a winding deviation of 1 mm or more occurs at the edge of one electrode and the other electrode,
One or more wrinkles, and insulation resistance of 1 k when a voltage of 250 V is applied to the wound power generating element
The number of batteries having poor insulation properties such as Ω or less was examined.

In order to compare the output characteristics of the batteries of Examples 1 to 6 and Comparative Example 1, in a fully charged state (battery open circuit voltage: 4.1 V), at 25 ° C., 5 A for 10 seconds, and then at 20 A. By discharging for 10 seconds and then for 10 seconds at 50 A, the output value of each battery was obtained by extrapolating the current value at which the battery voltage became 2.5 V. Table 2 shows the results.

[0047]

[Table 2]

As shown in Table 2, in Examples 1, 2, 3, and 4, the winding deviation of the electrode of 1 mm or more observed in the winding step was smaller than that in Examples 5 and 6 and Comparative Example 1. Less,
Furthermore, the number of insulation failures caused by these factors has been reduced. On the other hand, in Examples 5 and 6 and Comparative Example 1,
The number of occurrences of winding deviation and winding wrinkles was larger than that of Examples 1, 2, 3, and 4, and the number of insulation failures caused by them was also large.

Further, from Table 2, the output for 10 seconds showed a larger value in Examples 1, 2, 3, and 4 than in Examples 5, 6, and Comparative Example 1. The result is that the number of wrinkles generated when winding the electrode and the separator is reduced, and the electrode and the separator can be wound densely, so that it is possible to increase the output of the battery. It has become.

Further, as can be seen from Table 1, Examples 5 and 6 in which the total area of the through-holes and / or cutouts is 10% or less of the area of the uncoated portion of the mixture layer are described. Whatever the shape, the smaller the proportion of the total area of the through-holes and / or cutouts, the smaller the effect obtained. Naturally, when the number of through holes or / and notches is small and the total area of the through holes or / and notches is 10% or less with respect to the area of the mixture layer uncoated portion. Yields similar results.

[0051]

According to the present invention, there is provided a power generating element in which a positive electrode plate, a separator, a negative electrode plate, and a separator are sequentially laminated, wound or laminated, and at least one of the positive and negative electrode plates is viewed from one end face of the power generating element. In a non-aqueous electrolyte secondary battery in which only the edge of the electrode plate is protruded, a through-hole or / and a notch is formed in the mixture uncoated portion provided on the base material at the edge of the protruded electrode plate. By forming, the difference in elongation rate between the base material of the mixture-applied part and the base material of the mixture-unapplied part when pressing the electrode plate is reduced, and the distortion of the electrode is reduced. By reducing the rate of occurrence of slippage or wrinkles when winding or laminating the electrode and the separator, the electrode and the separator can be densely wound or laminated, and the reliability is high. Providing high-output non-aqueous electrolyte secondary batteries Theft is possible.

[Brief description of the drawings]

FIG. 1 is a plan view showing a positive electrode plate used for a nonaqueous electrolyte secondary battery of the present invention.

FIG. 2 is a view showing the appearance of a long cylindrical wound power generating element.

FIG. 3 is a diagram showing an appearance of a power generating element.

FIG. 4 is a diagram showing an appearance of a power generating element in which a current collecting member is arranged.

FIG. 5 is a plan view of another example of the positive electrode plate used for the nonaqueous electrolyte secondary battery of the present invention.

FIG. 6 is a plan view of another example of the positive electrode plate used for the nonaqueous electrolyte secondary battery of the present invention.

FIG. 7 is a plan view of another example of the positive electrode plate used for the nonaqueous electrolyte secondary battery of the present invention.

FIG. 8 is a diagram showing a plan view of a positive electrode plate used in a conventional nonaqueous electrolyte battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 6 Positive electrode plate 2 Base material 3 Mixture layer 4 Mixture layer uncoated part 5 Through hole 7 Negative electrode plate 8 Separator 9 Core 10 Tape 11 Power generation element 12 Positive current collector 13 Negative current collector 14 Square through hole 15 Rectangular cutout 16 U-shaped cutout X Non-coated part at edge of positive electrode plate Y Non-coated part at edge of negative electrode plate

Continued on front page F-term (reference) 5H029 AJ02 AJ14 AK02 AK03 AK16 AK18 AL02 AL03 AL06 AL07 AL11 AL12 AL18 AM00 AM02 AM03 AM04 AM05 AM07 AM16 BJ14 BJ15 DJ07 DJ14 HJ12 5H050 AA02 AA19 BA17 CA02 CA03 CB08 CB11 CB12 CB14 CB15 CB29 DA04 FA05 FA06 FA10 GA04 HA12

Claims (1)

[Claims] 1. A power generating element comprising a positive electrode plate, a separator, a negative electrode plate, and a separator which are sequentially laminated, wound or laminated, and an end of at least one of the positive and negative electrode plates from one end face of the power generating element. In the non-aqueous electrolyte secondary battery in which only the edge is projected, a through-hole or / and a notch is formed in an uncoated portion provided on the base material at the edge of the projected electrode plate. Non-aqueous electrolyte secondary battery characterized by the above-mentioned.