JP3332783B2 - Lithium ion battery and method for injecting electrolyte in the 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 lithium ion battery and, more particularly, to a pouring structure and a pouring method for pouring an electrolyte into the battery.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable reduction in the size and weight of electronic devices, and accordingly, there has been a great demand for smaller and lighter batteries that serve as power supplies. In the field of primary batteries, small and lightweight batteries such as lithium batteries have already been put to practical use, but since these are primary batteries, they cannot be used repeatedly, and their uses have been limited. On the other hand, in the field of secondary batteries, lead storage batteries, nickel-cadmium storage batteries, nickel-hydrogen storage batteries, and the like have been conventionally used, but these have major problems in terms of reduction in size and weight.

Therefore, lithium-ion batteries have come into practical use as small, lightweight, high-capacity, chargeable / dischargeable batteries, and are used in portable electronic and communication devices such as small video cameras, mobile phones, and notebook personal computers. Is now available. This type of lithium ion battery uses a carbon-based material capable of inserting and extracting lithium ions as a negative electrode active material, and uses LiCoO ₂ , LiNiO ₂ , L as a positive electrode active material.
using IMN ₂ O _4, LiFeO lithium-containing transition metal oxides such as _2, the ion conductor obtained by dissolving a lithium salt as a solute using an organic solvent as an electrolytic solution, after assembling the battery, the positive electrode active material by the first charging This is a battery in which lithium ions discharged from the battery enter the carbon particles and can be charged and discharged.

In this lithium ion battery, a positive electrode plate and a negative electrode plate are formed by coating a positive electrode active material and a negative electrode active material on a metal core (foil), respectively, and a separator is interposed therebetween and wound to form an electrode. . After inserting this electrode body into a metal outer can, the outer can is sealed with a sealing body. After this,
The battery pack is assembled by filling the outer can with an electrolyte through a liquid injection hole provided in the sealing body and sealing the liquid injection hole.

[0005]

However, in such a lithium ion battery, there is usually one liquid injection hole provided in the sealing body. If there is only one injection hole, even if the electrolyte is pumped into the outer can through the injection hole provided in the sealing body, there is no place for gas in the outer can to escape. It was difficult to enter and the problem of overflowing over the sealing body occurred. When the electrolyte overflows onto the sealing body, the overflowed electrolyte is deposited and powdered, which causes a problem that it becomes an obstacle in sealing the injection hole to be performed later.
Furthermore, if the injection hole is sealed while the overflowed, precipitated and powdered electrolyte is left as it is, there is a problem that a leak may occur.

Accordingly, the present invention has been made in view of the above problems, and has a liquid injection structure in which the electrolyte injected into the outer can does not overflow, and the electrolyte can be injected smoothly. Is to do so.

[0007]

Means for Solving the Problems and Action / Effect The present invention relates to a method of winding a positive electrode plate and a negative electrode plate through a separator.
The formed electrostatic polar body in a state housed in the metallic made outer Sokan,
Positioning at the outer Sokan'nai the same electrode material on top of said conductive electrode body
Place a spacer to hold because spaced above the same spacer
By closing the opening of the outer can with a sealing body arranged
Assembled and provided with at least two
The gas in the outer can is discharged from one of the liquid ports.
The electrolyte solution from the other injection port provided in the enclosure
A lithium-ion battery that can be injected into the can
Therefore , each of the liquid inlets of the sealing body is provided on the spacer.
Provide corresponding communication holes and isolate these communication holes
It is characterized in that the partition wall is formed to extend to the lower surface of the sealing body.
To provide lithium-ion batteries
is there.

[0008] As in the lithium ion battery described above, when the set Keru way at least two Note liquid holes in the sealing member, either pouring when injected the electrolytic solution from the hole the other injection hole than the outer can Gas is discharged, so that gas-liquid replacement can be performed smoothly. for that reason,
The gas existing in the outer can can be easily discharged, and the electrolyte solution corresponding to the discharged gas can be smoothly injected into the outer can. Therefore, it is possible to easily solve the problem that the electrolyte overflows onto the sealing body, and it is possible to immediately proceed to the step of sealing the injection hole after the injection. The productivity is improved and the yield is also improved.

Further, since the spacer is provided with a partition for partitioning between the communication holes extending to the lower surface of the sealing body, the injection of the electrolytic solution and the discharge of the gas in the outer can are performed through separate injection holes. As a result, gas / liquid replacement is performed efficiently.

Further, the present invention provides a method for separating a positive electrode plate and a negative electrode plate from each other.
The electrode body formed by winding through a heater is placed inside a metal outer can.
At housed state, the front of the same electrode material on top of the electrode body
Place a spacer for positioning and holding in the outer can.
The above-mentioned sealing body is spaced apart above the spacer.
Lithium ion assembled by sealing the opening of the outer can
In the battery, at least two notes provided on the sealing body
The above-mentioned space corresponds to one of the liquid ports and the same liquid port.
Gas in the outer can through the communication hole
While the other injection port provided on the sealing body and the same injection port
Correspondingly, the electrolyte is passed through the communication hole provided in the spacer.
How to inject the electrolytic solution into the outer can
To implement the law.

[0011] In the practice of the pouring process, it is possible to injected an electrolytic solution other injection hole while evacuating from small crows and <br/> also one injection hole. Therefore, the gas existing in the outer can can be easily discharged, and the electrolytic solution in an amount corresponding to the discharged gas can be smoothly injected into the outer can. Therefore, it is possible to easily solve the problem that the electrolyte overflows onto the sealing body, and it is possible to immediately proceed to the step of sealing the injection hole after the injection. The productivity is improved and the yield is also improved.

Further, since the spacer is provided with a partition for partitioning between the communication holes, the exhausted injection hole is provided before the electrolyte injected from the other injection hole is impregnated into the electrode body. Direct discharge from the inserted exhaust pipe can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the lithium ion battery of the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a view showing a main part of the lithium ion battery of the present embodiment, FIG. 1A is a top view showing a state where a sealing body is attached to an outer can, and FIG. FIG. 1C is a top view showing a state before mounting. FIG.
1A is a cross-sectional view showing an AA cross section, and FIG. 1D is a cross-sectional view showing a BB cross section of FIG.
(E) is a sectional view showing a CC section of FIG. 1 (c).
FIG. 2 is a view showing a sealing body of the present embodiment.
(A) is a top view, and (b) of FIG.
It is sectional drawing which shows D cross section, and FIG.2 (c) is a bottom view. Further, FIG. 3 is a view showing the spacer of the present embodiment, FIG. 3 (a) is a top view, and FIG. 3 (b) is a side view thereof.

A. Preparation of Electrode Body A mixture of a negative electrode active material made of natural graphite and a binder made of polyvinylidenefluoride (PVDF) dissolved in an organic solvent made of N-methylpyrrolidone and the like is mixed with a slurry or paste. I do. These slurries or pastes are prepared by using a die coater, a doctor blade or the like in the case of a slurry, or a metal core (for example, copper foil) by a roller coating method or the like in the case of a paste.
To form a negative electrode plate coated with an active material layer.

Thereafter, the negative electrode plate coated with the active material layer is passed through a drier to remove an organic solvent necessary for preparing a slurry or a paste, followed by drying. The dried negative electrode plate is rolled by a roll press to form a negative electrode plate.

On the other hand, a positive electrode active material composed of LiCoO ₂ , a carbon-based conductive agent such as acetylene black and graphite, a binder composed of polyvinylidene fluorite (PVDF), and the like are combined with an organic solvent composed of N-methylpyrrolidone. Are mixed to form a slurry or paste. Note that additives such as polyethylene oxide, polyacrylonitrile, and cellulose may be added to the slurry or paste.

These slurries or pastes are uniformly applied to both surfaces of a metal core (for example, aluminum foil) by using a die coater, a doctor blade or the like in the case of a slurry, or by a roller coating method in the case of a paste. Then, a positive electrode plate coated with the active material layer is formed.

Thereafter, the positive electrode plate coated with the active material layer is passed through a drier to remove an organic solvent necessary for preparing a slurry or a paste, followed by drying. After drying, the dried positive electrode plate is rolled by a roll press to obtain a positive electrode plate.

A negative electrode plate and a positive electrode plate prepared as described above are sandwiched between a microporous film made of an inexpensive polyolefin-based resin having low reactivity with an organic solvent, preferably a polyethylene microporous film. And wound by a winder (not shown). Thereafter, the outermost periphery is taped to form a spiral electrode body, and then formed into a shape that can be inserted into a rectangular outer can with a press machine to obtain an electrode body.

B. Production of Lithium-ion Battery Then, a bottomed cylindrical prismatic outer can made of an aluminum alloy formed by pressing from one sheet (for example, the outer dimensions are 46 mm in height, 22 mm in width, 7.5 mm in thickness, and 0 mm in thickness) The electrode body manufactured as described above is inserted into the outer can 10 through the opening of (0.5 mm). The outer can 10 also functions as a positive electrode terminal.

After the electrode body is inserted into the outer can 10, a spacer 20 is placed on the upper part of the electrode body. Here, the spacer 20 is provided for holding the electrode body inserted into the outer can 10 so as not to move, and extends upward at the center portion thereof as shown in FIGS. 1 and 3. A partition wall 25 is disposed, a first liquid injection communication hole 21 and a positive electrode conductive tab through hole 23 are disposed on the left side of the partition wall 25, and a second liquid injection communication hole 22 and a negative electrode Through hole 2 for conductive tab
4 are arranged. In addition, the partition 25 is a sealing body 3 described later.
0 is formed to extend to the lower surface.

When the spacer 20 is mounted on the upper part of the electrode body, the positive electrode conductive tab 40 extending from the positive electrode of the electrode body is passed through the positive electrode conductive tab through hole 23 so that the positive electrode conductive tab 40 is The negative electrode conductive tab 50 protrudes above the spacer 20 while passing the negative electrode conductive tab 50 extending from the negative electrode of the electrode body through the negative electrode conductive tab through hole 24.

Thereafter, the positive electrode current collecting lead plate 41 welded to the outer can 10 and the positive electrode conductive tab 40 are welded and fixed to a negative electrode terminal 52 attached to a terminal hole 33 of the sealing body 30 described later. The negative electrode current collecting lead plate 51 and the negative electrode conductive tab 50 are welded. Next, after placing the sealing body 30 in the opening of the outer can 10, the periphery of the sealing body 30 and the outer can 10 are welded.

Here, the sealing body 30 is provided for sealing the opening of the outer can 10, and faces the partition wall 25 of the spacer 20 at the center as shown in FIGS. A first liquid injection hole 31 is provided on the left side of the position, and a second liquid injection hole 3 is provided on the right side of the position facing the partition 25 of the spacer 20.
2 and a through hole 33 for the negative electrode terminal. A peripheral wall 34 protruding from the upper surface of the sealing body 30 is provided around the upper part of the sealing body 30.

After the sealing body 30 is placed on the opening of the outer can 10 and the periphery thereof is welded to the outer can and sealed, 30 parts by weight of ethylene carbonate (EC) and diethyl An electrolyte obtained by adding 1M LiPF6 as an electrolyte salt to a mixed solvent composed of 70 parts by weight of carbonate (DEC) is injected. At this time, a pipe extending from a suction device (not shown) is inserted into the second liquid injection hole 32 to insert the outer can 10.
The electrolytic solution is injected into the first injection hole 31 while the gas inside is sucked. After the electrolyte is injected, the injection holes 31 and 32 are sealed, and then a predetermined charging process is performed to obtain a lithium ion battery of the present embodiment.

The electrolyte is an ionic conductor in which a lithium salt is dissolved as a solute in an organic solvent and has a high ionic conductivity and is chemically and electrochemically stable with respect to each of the positive and negative electrodes. Therefore, use an inexpensive one that has a wide usable temperature range, high safety, and low cost. For example, as the organic solvent, in addition to the above-mentioned mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC), propylene carbonate (PC), sulfolane (SL), tetrahydrofuran (THF), γ-butyrolactone (GBL),
Dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), 1,2 dimethoxyethane (DME)
Or a mixed solvent thereof is suitable. As the solute, a lithium salt having a strong electron-withdrawing property is used.
In addition to iPF6, for example, LiBF4, LiClO4, L
iAsF6, LiCF3SO3, Li (CF3SO2)
2N, LiC4F9SO3 and the like are preferred.

C. Experimental Results An injection experiment was performed using the lithium ion battery of the present embodiment manufactured as described above and the battery of the comparative example having only one injection hole manufactured by the conventional method, using 10,000 each. When the number of times of dispensing and the defective rate of the sealed can were obtained, the results shown in Table 1 below were obtained. The number of times of dispensing means that if a predetermined amount of electrolyte is to be injected into the outer can 10 with only one injection, the electrolyte overflows from the injection hole 31 or 32 and is divided into several times. Means the number of times

[0028]

[Table 1]

As is evident from Table 1, in the lithium ion battery of the present invention, the number of dispensing operations is reduced, and the defective rate of sealed cans is significantly reduced. The reason why the number of dispensing is reduced is that the pipe extending from the suction device is inserted into the second liquid injection hole 32 and the electrolyte is drawn into the first liquid injection hole 31 while the gas in the outer can 10 is sucked. Into the outer can 10 in an amount equivalent to the discharged gas.
This is because the amount of electrolytic solution that can be injected at one time has been increased.

Further, the reduction in the rate of defective cans can be prevented by increasing the amount of electrolyte that can be injected at one time, thereby preventing the electrolyte from overflowing onto the sealing body. This is because precipitation and powdering do not occur, and no trouble occurs when the injection hole is sealed.

As described above, in this embodiment,
A first liquid injection hole 31 and a second liquid injection hole 32 are provided in the sealing body 30, and the electrolyte is supplied into the first liquid injection hole 31 while the gas in the outer can 10 is sucked through the second liquid injection hole 32. Therefore, an amount of electrolyte solution corresponding to the discharged gas can be smoothly injected into the outer can 10. Therefore, it is possible to easily solve the problem that the electrolyte overflows onto the sealing body, and it is possible to immediately proceed to the step of sealing the injection hole after the injection. The productivity is improved and the yield is also improved.

Further, since the spacer 20 is provided with the partition wall 25 extending to the lower surface of the sealing body 20, the first liquid injection hole 3 is formed.
It is possible to prevent the electrolyte injected from 1 from being directly discharged from the exhaust pipe inserted into the second injection hole 32 before being impregnated into the electrode body.

In the above embodiment, an example in which natural graphite is used as the negative electrode active material has been described. In addition to natural graphite, a carbon-based material capable of inserting and extracting lithium ions, for example, graphite, carbon black, Coke, glassy carbon, carbon fiber, or a fired body of these are suitable. Further, an oxide such as tin oxide or titanium oxide capable of inserting and extracting lithium ions may be used.

In the above-described embodiment, an example in which LiCoO ₂ is used as the positive electrode active material has been described. In addition to LiCoO ₂ , a lithium-containing transition metal compound capable of accepting lithium ions as a guest, for example,
LiNiO ₂ , LiCoXNi (1-X) O ₂ , LiCr
O ₂ , LiVO ₂ , LiMnO ₂ , αLiFeO ₂ , LiT
iO ₂ , LiScO ₂ , LiYO ₂ , LiMn ₂ O _{4 and the} like are preferable, and particularly, LiNiO ₂ , LiCoXNi (1-
X) or whether to use the O ₂ alone is used as a mixture of two or more thereof are preferred. Further, a conductive polymer such as polyacetylene or polyaniline may be used.

[Brief description of the drawings]

FIG. 1 is a view showing a main part of a lithium ion battery according to one embodiment of the present invention, and FIG. 1 (a) is a top view showing a state where a sealing body is attached to an outer can, and FIG. 1 (b). FIG. 1C is a top view showing a state before the sealing body is attached to the outer can, FIG. 1C is a cross-sectional view taken along the line AA of FIG. 1A, and FIG. 1C is a cross-sectional view showing a BB cross section, and FIG. 1E is a cross-sectional view showing a CC cross section of FIG. 1C.

FIG. 2 is a view showing the sealing body of FIG. 1, FIG. 2 (a) is a top view, and FIG. 2 (b) is a cross-sectional view showing a DD section of FIG. 2 (a); 2 (c) is a bottom view.

FIG. 3 is a view showing the spacer of FIG. 1, and FIG.
Is a top view, and FIG. 3B is a side view thereof.

[Explanation of symbols]

Reference Signs List 10: outer can (positive electrode terminal), 20: spacer, 21: first communication hole for liquid injection, 22: second communication hole for liquid injection, 23 ...
Through hole for positive electrode conductive tab, 24 ... Through hole for negative electrode conductive tab,
25 ... partition wall, 30 ... sealing body, 31 ... first liquid injection hole, 32
... Second liquid injection hole, 33 ... Negative electrode terminal through hole, 40 ... Positive electrode conductive tab, 41 ... Positive electrode current collecting lead plate, 50 ... Negative electrode conductive tab, 51 ... Negative electrode current collecting lead plate, 52 ... Negative electrode terminal

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 2/02-2/08 H01M 2/36 H01M 6/16-6/18

Claims (2)

(57) [Claims] 1. A state in which a positive electrode plate and the negative electrode plate polar body collector formed by winding via a separator is accommodated in a metal outer can
At the upper to the same electrode of the electrostatic polar body in in the outer Sokan
Above the place spacers for positioning hold Dosu pacer
Assembled in sealing the opening of said outer Sokan with a sealing member to be disposed apart from at least provided on the sealing body two
The gas in the outer can is discharged from one of the two inlets
Together with the electrolyte from the other inlet provided in the enclosure.
A lithium-ion battery which is adapted to inject into the interior of Kigaiso cans, to correspond to each liquid inlet of said sealing member to said spacer
Lithium-ion batteries the partition you isolate these communication holes provided with a communication hole, characterized in that formed extending to a lower surface of the sealing body that. 2. A state in which a positive electrode plate and the negative electrode plate polar body collector formed by winding via a separator is accommodated in a metallic made outer Sokan
At the upper to the same electrode of the electrostatic polar body in in the outer Sokan
A spacer for positioning retain arranged, above the same scan pacer
In the lithium-ion batteries which is assembled by sealing the opening of said outer Sokan with a sealing member to be arranged separately, one of the at least two liquid injection port provided on the sealing body
Of the spacer corresponding to the liquid inlet of
The above-mentioned sealing is performed while sucking the gas in the outer can through the through hole.
The above-mentioned switch corresponds to the other liquid inlet provided in the mouth and the same liquid inlet.
The electrolyte solution is passed through the communication hole provided in the pacer to the inside of the outer can.
A method for injecting an electrolytic solution to be injected into the part .