JPH06302337A - Battery - Google Patents

Abstract

PURPOSE:To make an electrolyte pouring operation easy by impregnating a solvent which is a component of an electrolyte in a positive electrode or a negative electrode, then forming a battery element with a separator interposed between the electrodes. CONSTITUTION:At least one solvent which is a component of an electrolyte is impregnated in a positive electrode 2 or a negative electrode 1, then a separator 3 is interposed between the electrodes to form a battery element. The solvent is impregnated in the battery element, the battery element is accommodated into a battery container. The battery container is a battery can 4 made of nickel plated steel, and an insulating plate 5 is placed on the bottom of the battery can 4. A negative lead 6 from the battery element is welded to the bottom of the battery can 4, and the electrolyte is poured into the battery can 4. An insulating plate 5 is placed on the top of the battery element, a gasket 7 is fitted, and an explosion prevention valve 8 is installed inside a battery. A positive lead 9 is welded to the explosion prevention valve 9, then the battery is covered with a sealing cover 10. The electrolyte capable of providing maximum performance is simply selected and the electrolyte is easily poured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art As electronic devices are being made smaller and lighter, there is an increasing demand for batteries having high energy density as batteries for their power sources. In order to meet the demand, non-aqueous electrolyte batteries are being put into practical use because of their high potential as high energy density batteries. Existing alkaline batteries, nickel-cadmium batteries, lead batteries, etc. are excellent in heavy load characteristics, and in order to replace these existing batteries, sufficient non-aqueous electrolyte secondary batteries are also required to have heavy load characteristics. The electrolyte used in the non-aqueous electrolyte battery has a resistance that is 50 times higher than that of the aqueous electrolyte used in the existing nickel-cadmium battery and lead battery. In order to compensate for this handicap of the electrolytic solution and obtain sufficient heavy load characteristics, in the case of a non-aqueous electrolytic solution battery, an extremely thin electrode is used, and the number of electrodes is increased to increase the electrode area. In the case of a cylindrical battery, the battery element is configured as a wound body in which an electrode as long as possible is rolled up in multiple layers. However, it is difficult for the electrolyte solution to permeate the battery element of such a non-aqueous electrolyte battery, and the electrolyte injection step is a major bottleneck in the manufacture of the non-aqueous electrolyte battery. In particular,
In the electrolytic solution injecting step, if the required amount of electrolytic solution is injected at one time, the electrolytic solution does not permeate the battery element so badly that it overflows from the battery container. Therefore, inject a small amount of electrolytic solution to maintain a decompressed state to promote the permeation of the electrolytic solution into the battery element, and inject a small amount of electrolytic solution to perform the same operation. Repeat until the amount is reached. In the case of a slightly large battery, the number of times reaches 10 or more. Furthermore, recently, a non-aqueous electrolyte secondary battery having a negative electrode of a carbon electrode that utilizes the inflow / outflow of lithium ions from / to carbon has been under development. This battery is said to be a lithium-ion type or rocking chair type secondary battery. Typically, LiCoO ₂ , LiMn ₂ O ₄ , etc. are used for the positive electrode material, and carbonaceous materials such as coke and graphite are used for the negative electrode. Used. The carbon negative electrode is extremely stable because the carbon helium ion in the electrode is doped during charging and the lithium ion is undoped from the carbon during discharging, and the carbon itself does not undergo a large change in crystal structure during charging and discharging. Shows the charged and discharged characteristics,
Characteristic deterioration due to charging and discharging is small, and specifically, it is possible to repeat charging and discharging 1000 times or more. In particular, when graphite is used as the carbon material, the discharge voltage is flat and high, so that the battery can have a very large energy density. However, batteries having graphite as a negative electrode have extremely poor charging efficiency. This is because the carbon doped with lithium basically reacts with the electrolytic solution. Fortunately, if ethylene carbonate (EC) is mixed into the electrolytic solution, the charging efficiency is dramatically improved. . However, the electrolytic solution mixed with ethylene carbonate (EC) not only has poor permeability of the electrolytic solution into the electrode element in the electrolytic solution injecting step, but also causes a problem. That is, in the battery manufacturing process, a certain amount of electrolyte is generally injected by a precision pump through a thin nozzle. At this time, since the melting point of ethylene carbonate (EC) is as high as 39 ° C., ethylene carbonate (EC) is immediately deposited at the tip of the electrolyte solution injection nozzle, and the electrolyte solution injection becomes impossible.

[0003]

Therefore, the present invention is intended to solve the problem of the electrolytic solution injecting step in the production of the non-aqueous electrolytic solution battery.

[0004]

The means for solving the above-mentioned problems is to impregnate at least one of positive and negative electrodes with at least one solvent constituting an electrolytic solution, and then sandwich a separator between the positive and negative electrodes. Depending on whether a battery element is prepared or a battery element constituted by sandwiching a separator between positive and negative electrodes is impregnated with at least one solvent constituting an electrolytic solution before putting the battery element in a battery container. After containing the solvent in the battery container, it is placed in a battery container, and an electrolytic solution composed of the remaining composition elements is injected into the battery container to prepare a non-aqueous electrolyte battery.

[0005]

In general, most non-aqueous battery electrolytes are actually used as a mixture of two or more kinds of solvents in order to improve various battery characteristics. In the present invention, among the solvents constituting the electrolytic solution, a solvent having a high melting point such as ethylene carbonate or a solvent having poor permeability to the battery element such as propylene carbonate is used in the battery element before being stored in the battery container. Since it is contained, at the time of injecting the electrolytic solution in the battery manufacturing process, the electrolytic solution composed of a solvent having better permeability or the electrolytic solution containing no high melting point solvent is injected, so that the electrolytic solution is impregnated into the battery element. Also, the electrolyte injection nozzle tip is not clogged, and problems in the electrolyte injection process are eliminated.

[0006]

The present invention will be described in more detail with reference to the following examples.

Example 1 A specific battery of the present invention will be described with reference to FIG. A battery element which is a power generation element for carrying out the present invention is prepared as follows. 85 parts by weight of commercially available powdery graphite and 15 parts by weight of polyvinylidene fluoride (PVDF) as a binder are used as a solvent N-methyl-2-
Wet mix with pyrrolidone to form a slurry (paste form). Next, this slurry is used as a negative electrode current collector in a thickness of 0.0
A 1 mm copper foil is evenly applied on both sides, dried, and then pressure-molded by a roll press machine to obtain a strip-shaped negative electrode body. This strip-shaped negative electrode body was prepared by heating ethylene carbonate (E
It is dipped in C) to obtain a strip-shaped negative electrode strip (1a) impregnated with ethylene carbonate (EC). The positive electrode is prepared as follows. Commercially available manganese dioxide (MnO ₂ )
And lithium carbonate (Li ₂ CO ₃ ) molar ratio 1: 0.25
The mixture consisting of
Adjust Mn ₂ O ₄ . Next, 86 parts by weight of LiMn ₂ O ₄ , 10 parts by weight of graphite as a conductive agent, and 4 parts by weight of polyvinylidene fluoride as a binder were N-methyl-2.
Wet mix with pyrrolidone to form a paste. This paste is uniformly applied to both surfaces of an aluminum current collector having a thickness of 0.02 mm, dried and pressure-molded with a roller press to form a strip-shaped LiMn ₂ O ₄ electrode (2a). Subsequently, the negative electrode (1a) and the positive electrode (2a) are wound into a roll with a porous polypropylene separator (3) sandwiched between them to prepare a battery element having an average outer diameter of 15.7 mm.
An insulating plate (5) is installed on the bottom of a nickel-plated iron battery can (4) to house the battery element. Negative electrode lead (6) taken out from the battery element was welded to the bottom of the battery can, and 1 mol / liter of LiPF ₆ was dissolved in the battery can as an electrolytic solution diethyl carbonate (DEC).
Inject the solution. Then, the insulating plate (5) is also installed on the upper part of the battery element, the gasket (7) is fitted, and the explosion-proof valve (8) is installed inside the battery as shown in FIG. The positive electrode lead (9) taken out from the battery element is welded to this explosion-proof valve, and the closing lid body (1
0) are stacked with a doughnut-type PTC switch (11) sandwiched therebetween and the edges of the battery can are crimped to complete a battery (A) having an outer diameter of 16.5 mm and a height of 65 mm with the battery structure shown in FIG.

Example 2 An example of another method of the present invention, which is slightly different from Example 1, will be shown. For this embodiment, the battery element is no different from the battery element for batteries made by conventional methods.
That is, 15 parts by weight of polyvinylidene fluoride (PVDF) as a binder was added to 85 parts by weight of powdered graphite,
Wet mix with a solvent, N-methyl-2-pyrrolidone, to form a slurry (paste). This slurry is uniformly applied to both surfaces of a 0.01-mm-thick copper foil serving as a negative electrode current collector, dried, and pressure-molded with a roll press to form a strip-shaped negative electrode (1b). After that, the negative electrode (1b) and the same positive electrode (2a) as that prepared in Example 1 were wound into a roll with a porous polypropylene separator (3) interposed therebetween, and a battery element having an average outer diameter of 15.7 mm. To create.
So far, there is no difference from the conventional method, but the battery element prepared here is immersed in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a weight ratio of 3: 7, and this mixed solvent is depressurized. After being sufficiently impregnated into the battery element, it is sufficiently dried in a vacuum dryer kept at 30 ° C. The dried electrode element is impregnated with about 1.5 g of ethylene carbonate. The dried electrode element is installed in an insulating plate (5) provided on the bottom of a nickel-plated iron battery can (4). After that, Example 1
A battery (B) is prepared in the same manner as in.

Comparative Example 1 In order to confirm the effect of the present invention, a battery (E) and a battery (F) according to the conventional method are prepared. As the battery (E), the battery element prepared in Example 2 is used, and thereafter, the battery (E) is prepared in the same manner as in Example 1. That is, the battery (E) according to the conventional method is different from that of Example 1 only in that the negative electrode is not impregnated with ethylene carbonate. The battery (F) according to the conventional method is the same as the battery element prepared in Example 2,
As the electrolytic solution, a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) in which 1 mol / liter of LiPF ₆ is dissolved is used. Otherwise, the battery (F) is prepared in the same manner as the battery (E).

Example 3 90 parts by weight of powdered pitch coke and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder were wet-mixed with N-methyl-2-pyrrolidone as a solvent to form a slurry (paste form). To Next, this slurry is uniformly applied to both surfaces of a copper foil having a thickness of 0.01 mm, which serves as a negative electrode current collector, dried, and then pressure-molded by a roll press machine to form a strip-shaped negative electrode strip. This strip-shaped negative electrode body was dipped in propylene carbonate (PC) to obtain propylene carbonate (P
A strip-shaped negative electrode strip (1c) impregnated with C) is obtained. The positive electrode is prepared as follows. Commercially available lithium carbonate (Li ₂
CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed so that the atomic ratio of Li and Co is 1.03: 1, and the mixture is calcined in air at 900 ° C. for about 5 hours to obtain LiCoO ₂ .
Next, 91 parts by weight of this LiCoO ₂ , 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of vinylidene fluoride as a binder were wet-mixed with N-methyl-2-pyrrolidone as a solvent to form a slurry (paste form). To do. Next, this slurry is evenly applied to both sides of a 0.02 mm-thick aluminum foil serving as a positive electrode current collector, dried and pressure-molded with a roller press machine to form a strip-shaped positive electrode (2b). Subsequently, the negative electrode (1c) and the positive electrode (2b) are wound in a roll shape with a porous polypropylene separator (3) interposed therebetween to prepare a battery element having an average outer diameter of 15.7 mm.
After that, the same electrolytic solution (diethyl carbonate solution in which 1 mol / liter LiPF ₆ was dissolved) was injected by the same procedure as in Example 1 to form a battery (C) with the same battery structure.

Comparative Example 2 In order to confirm the effect of Example 3 of the present invention, a battery (G) according to the conventional method is prepared. The battery (G) according to the conventional method is the same as that of the third embodiment except that the negative electrode and the electrolyte used are different from those of the third embodiment. The negative electrode for this comparative example is prepared as follows. 90 parts by weight of powdered pitch coke and polyvinylidene fluoride (PVDF) as a binder
10 parts by weight of N-methyl-2-pyrrolidone, which is a solvent, is wet mixed to form a slurry (paste). Next, this slurry is uniformly applied to both surfaces of a 0.01-mm-thick copper foil that serves as a negative electrode current collector, dried, and then pressure-molded with a roll press to form a strip-shaped negative electrode (1d). After that, the negative electrode (1d) and the same positive electrode (2b) prepared in Example 2 were wound into a roll with a porous polypropylene separator (3) interposed therebetween, and a battery element having an average outer diameter of 15.7 mm. To prepare 1 mol / l of Li as an electrolytic solution
A battery (G) is prepared in the same manner as in Example 3, except that a mixed solution of propylene carbonate (PC) and diethyl carbonate (DEC) in which PF ₆ is dissolved is used. Each of the battery according to the present invention and the battery according to the comparative example produced in this way is subjected to an aging period of 24 hours for the purpose of stabilizing the inside of the battery, and then the battery (A), the battery (B), the battery (E), And the battery (F) set the charging voltage to 4.2V, the battery (C) and the battery (G) set the charging voltage to 4.0V, and charged for 12 hours each, and the discharge was 800mA for all the batteries. The discharge capacity of each battery is determined by performing constant current discharge up to a final voltage of 2.5 V. The above results are shown in Tables 1 and 2. The batteries (A) and (B) according to the present invention do not contain ethylene carbonate in the electrolyte to be injected, so that ethylene carbonate does not deposit at the tip of the electrolyte injection nozzle and the nozzle is not clogged. Furthermore, since the electrolyte solution to be injected is an electrolyte solution containing only diethyl carbonate, it has good penetrability into the battery element, and one of the solvents (EC) that constitutes the final electrolyte solution in the battery is already the battery. Since the element is impregnated, the amount of the injected electrolytic solution is small accordingly. Therefore, the required amount of electrolytic solution can be injected by repeating the injection of the electrolytic solution three times, and a sufficient battery capacity can be obtained. On the other hand, in the batteries (E) and (F) according to the conventional method, the battery element does not contain any electrolytic solution component. Therefore, since the required amount of the electrolytic solution is completely filled in the battery by the injection, the injected amount of the electrolytic solution is larger than that in the case of the battery (A) or the battery (B) of the present invention. In addition, in the conventional battery (F), the electrolyte to be injected is an electrolyte containing ethylene carbonate, so a sufficient battery capacity can be obtained, but the electrolyte injection nozzle is clogged and it is necessary to replace the nozzle many times. In addition, the permeability of the electrolytic solution is poor, and in order to inject the required amount of the electrolytic solution, the number of injections must be divided into 11 times. On the other hand, in the battery (E) according to the conventional method in which the same electrolytic solution as that of the battery (A) or the battery (B) according to the present invention is injected, the permeability of the electrolytic solution into the battery element is good, and the number of injections of the electrolytic solution is small. Although the required amount of electrolytic solution was injected four times, the completed battery does not contain ethylene carbonate in the electrolytic solution in the battery, so it is not charged well, and the essential battery capacity cannot be obtained at all. When graphite is used as the negative electrode active material, ethylene carbonate is an essential solvent in the final electrolytic solution composition in the battery. When coke is used as the active material carbon of the negative electrode as in the batteries (B) and (G) in Example 2 and Comparative Example 2, propylene carbonate can be used instead of ethylene carbonate. The melting point of propylene carbonate is sufficiently low, and the problem of clogging of the electrolyte injection nozzle does not occur. However, the electrolyte solution containing propylene carbonate has a poor permeability to the battery element, and thus the battery (B) according to the present invention can significantly reduce the number of times of electrolyte injection as compared with the battery (G) according to the conventional method.

[0012]

EFFECTS OF THE INVENTION According to the present invention, the electrolyte selected to bring out the best performance in the non-aqueous electrolyte battery is applied to a battery element such as a solvent having a high melting point such as ethylene carbonate or propylene carbonate. Even if it is unavoidable to use a solvent with poor permeability, the solvent is impregnated into the battery element outside the battery container, and then the battery element is housed in the battery container, and the electrolyte injection into the battery container is more permeated. It is possible to inject an electrolyte solution composed of a solvent with good properties or an electrolyte solution that does not contain a high melting point solvent, the impregnation of the electrolyte solution into the battery element is fast, there is no clogging at the tip of the electrolyte solution injection nozzle, and the electrolyte solution is injected. Easy to do. As a result, even for non-aqueous electrolyte batteries of any battery system, the electrolyte with the optimum solvent composition can be simply selected to obtain the best performance, and batteries with excellent characteristics that can be used in a wide range of applications can be easily mass-produced. It is possible to do so, and its industrial value is great.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structures of batteries in Examples and Comparative Examples.

[Explanation of symbols]

1 is a negative electrode, 2 is a positive electrode, 3 is a separator, 4 is a battery can, 5
Is an insulating plate, 6 is a negative electrode lead, 7 is a gasket, 8 is an explosion-proof valve, 9 is a negative electrode lead, and 10 is a closing lid.

Claims (2)

[Claims] 1. A battery having a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution, and at least 1 constituting an electrolytic solution.
A non-aqueous electrolyte battery, wherein at least one of positive and negative electrodes is impregnated with a solvent of a seed, and a separator is sandwiched between the positive and negative electrodes to form a battery element. 2. A battery having a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution. A battery element having a separator sandwiched between positive and negative electrodes, and at least an electrolyte solution being contained therein before being housed in a battery container. A non-aqueous electrolyte battery, which is prepared by impregnating one type of solvent, then placing the battery element in a battery container, and injecting an electrolytic solution composed of the remaining composition elements into the battery container.