JPH0594816A - Impregnating method for battery - Google Patents

Abstract

PURPOSE:To impregnate an electrolyte to numerous batteries rapidly and securely while avoiding a moisture absorption by soaking battery cans in the electrolyte making their opening ends face downward in a reduced pressure condition, and then increasing the pressure. CONSTITUTION:Numerous battery cans 4 of nonaqueous secondary batteries in which a positive electrode and a negative electrode are housed through a separator respectively are set in an impregnation tank 1 making their opening ends face downward, and the electrolyte passage of an electrolyte tank 6 is cut off to evacuate the air in the tank 1. Then, the cans 4 are lowered by an up and down movement mechanism 2, the opening ends of the cans 4 are soaked in the electrolyte to a specific depth, an air of the dew point -50 deg.C is fed, and the pressure is increased to 2kgG/cm<2>. As a result, the electrolyte is sucked up into the cans 4, and the electrolyte is impregnated rapidly and securely without absorbing the moisture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for impregnating a battery.

More specifically, it relates to a method of impregnating an electrolytic solution in a manufacturing process of a non-aqueous secondary battery.

[0003]

2. Description of the Related Art In recent years, for example, a lithium-transition metal composite oxide capable of dedoping and doping lithium ions as disclosed in JP-A-62-90863 has been used as a positive electrode active material. A battery characterized by using a carbonaceous material that can be doped and dedoped as a negative electrode active material has been attracting attention as a secondary battery that is small, lightweight, has a high capacity, and is safe. The battery is
The electromotive force is about 4 V at maximum, which is three times or more that of the conventional nickel-cadmium battery. Therefore, the aqueous electrolytic solution cannot be used because it causes electrolysis, and it is necessary to use the non-aqueous electrolytic solution.

In general, since the non-aqueous electrolyte solution has low ionic conductivity, it is necessary to increase the electrode surface area in this type of battery to maintain high output power capable of extracting more current for a certain period of time. For this purpose, it is effective to use a thin polyolefin porous film or a non-woven fabric as a separator.

However, since the non-aqueous electrolyte has a very high polarity and a large surface tension, it is difficult for the non-polar polyolefin-based separator to get wet, and in the battery, the electrolyte is used as an electrode body composed of an electrode and a separator. The process of uniform impregnation took a very long time.

As disclosed in JP-A-2-244568, addition of a surfactant is effective for increasing the impregnation rate, but still, a sufficient impregnation effect is not obtained by a usual impregnation method. I can't expect. JP-A-2-172
Japanese Patent No. 158 discloses a vacuum pressure impregnation method in which a liquid reservoir is installed in a can opening, but it is difficult to maintain close contact between the liquid reservoir and the can, and a complicated mechanism is required for mass production. Becomes A dispenser can be used for quantitative dispensing, but it is not suitable for mass production because the device and piping are complicated.

Furthermore, the non-aqueous electrolyte has a strong hygroscopic property, and the mixed water significantly impairs the characteristics of the battery. Therefore, the impregnation operation must be carried out sufficiently quickly.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a non-aqueous secondary battery in which positive and negative electrodes are arranged opposite to each other with a separator interposed between them and housed in a battery can. The purpose is to ensure impregnation.

[0009]

In order to achieve the above object, the present invention is directed to a non-aqueous secondary battery manufacturing process in which positive and negative electrodes are arranged so as to face each other with a separator interposed therebetween and housed in a battery can. The battery can is characterized in that it is immersed in an electrolytic solution under reduced pressure with its open end facing downward, and then pressurized.

The present invention will be described in detail below.

First, the air in the battery can is removed by placing the battery can in an impregnation tank capable of depressurizing and pressurizing, and by placing it under a reduced pressure of preferably 30 mmHg or less.

[0012] Further, the electrolytic can is introduced into the impregnation tank with the open end of the battery can facing downward, or the battery can is lowered into the electrolytic solution of the tank in which the electrolytic solution is stored in advance, and By immersing the opening in the electrolytic solution and then applying pressure, the electrolytic solution rapidly penetrates into the battery can under reduced pressure.
After a certain period of time, the electrolyte solution in the impregnation tank is discharged to the outside of the tank, or the battery can is pulled up from the electrolyte solution,
Excessive electrolytic solution remaining on the open end side of the battery can is recovered, and rapid impregnation is completed.

According to the present invention, leakage of the impregnation tank is eliminated, and the gas for pressurization is dehumidified in advance, so that the problem that the electrolytic solution absorbs moisture can be solved. Furthermore,
It is preferable that the electrolytic solution is always brought into contact with a desiccant such as molecular sieves to further dehumidify.

When the portion of the battery can to be immersed in the electrolytic solution is limited to the vicinity of the open end of the battery can, it is possible to reduce the adhesion of the electrolytic solution to the outer wall of the battery can. The time and effort required to wipe off the attached electrolyte solution can be greatly saved. The less the immersed part, the smaller the amount of electrolyte that adheres to the outer wall of the battery can, but if the immersed part is too small, the pressurized gas will enter the battery can during pressurization, causing insufficient impregnation. .. The most preferable immersion depth is 5 to 10 mm from the open end of the battery can.

When the excess electrolytic solution remains in the battery can that has been separated from the electrolytic solution reservoir after the impregnation, the excessive electrolytic solution should be removed to reduce the weight of the battery can. is there. Furthermore, when gas is generated in the battery can due to the battery being charged with an abnormally high voltage, the space after removing the excess electrolytic solution effectively functions as a gas reservoir. In the present invention, it is particularly preferable to use a method in which the excess electrolytic solution is discharged by separating the opening of the battery can from the electrolytic solution reservoir after the impregnation and reducing the pressure again.

When it is necessary to remove the electrolytic solution adhering to the outer wall of the battery can after impregnation with the electrolytic solution, the electrolytic solution adhering to the outer wall of the battery can gathers as droplets when a compressed gas is blown at high speed, Furthermore, it is effective to blow the compressed gas to the outer wall of the battery can by utilizing the property of scattering in the form of mist. The flow velocity of the compressed gas is preferably about 500 m / sec and the diameter is 0.
It is efficient to spray it obliquely downward from the nozzle opening of about 5 mm toward the battery can. By dehumidifying the compressed gas to be blown in advance, moisture absorption can be prevented and the process can proceed to the next step more quickly.

The structure of the battery to which the impregnation method of the present invention can be applied is not particularly limited, but a positive electrode electrode, a negative electrode, and a negative electrode, which are opposed to each other with a separator interposed therebetween, and are wound up in a roll shape to have a cylindrical shape. Inserted into a battery can, crushing the electrode body, inserted into a flat cylindrical or rectangular battery can, positive and negative electrodes are placed facing each other via a separator and folded to form a flat cylindrical or For example, the one inserted into a rectangular battery can is given.

The separator of the battery used in the present invention is not particularly limited, but the effect of the present invention is remarkable when a polyethylene or polypropylene separator is used. Specifically, for example, a porous film of polypropylene, a porous film of polyethylene, a nonwoven fabric of polypropylene, a nonwoven fabric of polyethylene, or a laminated product of these is used.

Examples of non-aqueous electrolytes include ethers, ketones, lactones, nitriles, amines, amides, sulfur compounds, chlorinated hydrocarbons, esters, carbonates, nitro compounds, Phosphate ester compounds, sulfolane compounds and the like can be used, and among these, ethers, ketones, nitriles, chlorinated hydrocarbons, carbonates and sulfolane compounds are preferable. More preferred are cyclic carbonates.

As typical examples of these, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, anisole, monoglyme, acetonitrile, propionitrile, 4-methyl-2-pentanone, butyronitrile, valeronitrile, benzonitrile, 1 , 2-
Dichloroethane, γ-butyrolactone, dimethoxyethane, methyl formate, propylene carbonate, ethylene carbonate, vinylene carbonate, dimethylformamide, dimethylsulfoxide, dimethylthioformamide, sulfolane, 3-methyl-sulfolane, trimethyl phosphate, triethyl phosphate, and triethyl phosphate thereof. Examples of the mixed solvent include, but are not necessarily limited to, these.

The electrolyte of the non-aqueous electrolyte is not particularly limited, but as an example, LiClO ₄ , LiBF ₄ , L
iAsF ₆ , CF ₃ SO ₃ Li, LiPF ₆ , LiI,
LiAlCl ₄ , NaClO ₄ , NaBF ₄ , NaI,
(N-Bu) ₄ N ⁺ ClO ₄ , (n-Bu) ₄ N ⁺ BF ₄
, KPF _{6 and the} like.

[0022]

The present invention will now be described in more detail by way of examples, which do not limit the scope of the present invention.

Example 1 A positive electrode was prepared by adding the same amount of a 5% DMF solution of polyvinylidene fluoride to a compound prepared by adding 5% of a carbon-based conductive auxiliary agent to LiCoSn _0.02 O _{2 as} an active material, and a dispersion liquid. The aluminum foil having a thickness of 15 μm is uniformly applied at 300 g / m ² on each side and dried.

The negative electrode has an average particle size of 1 as an active material.
The same amount of 5% polyvinylidene fluoride DMF solution was added to 0 μm needle coke to obtain a dispersion, which was uniformly attached at 150 g / m ² on both sides of a stainless steel 304 foil with a thickness of 10 μm, and dried.

After sizing these positive and negative electrodes to a width of 40 mm and attaching a lead tab, a spiral coil is made through a polyethylene microporous membrane separator having a thickness of 35 μm.

The coil has a diameter of 15.5 mm and is inserted into a stainless steel can having an inner diameter of 15.6 mm and a length of 49.5 mm.

The electrolytic solution is a three-component solution of 1 mol / l LiBF ₄ , propylene carbonate, ethylene carbonate and γ-butyrolactone.

1 and 2 are conceptual diagrams of an impregnating device and a droplet removing mechanism used in this embodiment, respectively.

The battery can 4 is held by the work holding jig 3,
The battery can 4 is set in the impregnation tank 1 with the open end of the battery can 4 facing downward. In this state, the open end of the battery can 4 has not yet touched the electrolytic solution accumulated at the bottom of the impregnation tank 1. The electrolytic solution is supplied from the electrolytic solution tank 6 through the dehydration column 5 by the pump 7, and the surplus returns to the electrolytic solution tank 6 under a natural flow to keep the level in the electrolytic solution tank 1 constant.

After setting the battery can 4, the flow path of the electrolytic solution is shut off, the impregnation tank 1 is evacuated to 30 Pa, and the air in the battery can is removed. After about 2 minutes, the elevating mechanism 2 is operated to lower the battery can 4, and the open end of the battery can 4 is immersed in the electrolytic solution to a depth of 5 mm from the open end as shown in FIG. Then, the exhaust path is shut off, and air having a dew point of -50 ° C is sent to the impregnation tank 1 to pressurize it to ² kgG / cm ² and hold it for about 5 minutes. During this time, the electrolytic solution is sucked up by the battery can 4 and is quickly impregnated.

Next, the impregnation tank 1 is returned to normal pressure, and further 30
The pressure is reduced to mmHg, and the excess electrolytic solution in the battery can is discharged. Next, the impregnation tank 1 is returned to normal pressure, and the battery can 4 is moved together with the work holding jig 3 to the droplet removing mechanism shown in FIG. The droplet removing mechanism is provided with a nozzle 8 that blows air with a dew point of −50 ° C. toward the center of the open end of the battery can 4.
About 30 seconds after the battery can 4 is set, 6 l / min of air is blown from the nozzle 8 having a diameter of 0.5 mm to the electrolytic solution attached to the outer wall of the open end of the battery can 4. At this time, it is more effective to move the work holding jig 3 in parallel so that the air is uniformly hit. The electrolytic solution adhering to the outer wall of the battery can 4 is blown by the air flow, becomes large droplets, collects at the open end of the battery can 4, and finally scatters in a mist. The scattered electrolytic solution is collected by a mist separator attached to the lower part of the droplet removing device and discarded.

Then, the battery can is sealed to complete the battery.

When 100 batteries were impregnated, the amount of impregnating liquid was in the range of 4.15 to 4.51 g / cell,
The performance as a battery was also good. Immediately after the impregnation, the battery was disassembled, and the electrolytic solution was uniformly stained on the entire surface of the separator.

[0034]

As described above, according to the impregnation method of the present invention, the dispersion of the impregnated amount of the electrolytic solution can be made extremely small even during mass production, and further the entire surface of the separator can be uniformly impregnated. In addition, since the impregnation can be performed very quickly, it is possible to prevent moisture absorption of the electrolytic solution, which adversely affects the battery characteristics.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an impregnation device used in an example.

FIG. 2 is a conceptual diagram of a droplet removing mechanism used in the examples.

[Explanation of symbols]

 1 Impregnation tank 2 Lifting mechanism 3 Work holding jig 4 Battery can 5 Dehydration column 6 Electrolyte tank 7 Pump 8 Nozzle

Claims (1)

[Claims] 1. In a process of manufacturing a non-aqueous secondary battery, in which positive and negative electrodes are opposed to each other with a separator interposed therebetween and housed in a battery can, the battery can is placed under reduced pressure with its open end facing downward. A method for impregnating a battery, which comprises immersing the battery in an electrolytic solution and then applying pressure.