KR20020019008A - Battery and method of manufacture thereof - Google Patents

Abstract

A battery is manufactured by filling an electrolytic solution into a power generating element body in which an anode, a cathode, and a separator are integrally formed, removing a part of the adhered electrolyte solution, and storing it in an outer container.

Description

BATTERY AND METHOD OF MANUFACTURE THEREOF

The lithium ion secondary battery is a secondary battery capable of realizing high voltage and high energy density, and its quality is currently actively being improved. The main components of such a battery are a power generation element body consisting of a pair of electrodes of a positive electrode and a negative electrode and a separator which separates the positive electrode from short circuiting, and an electrolyte solution filled in the power generation element. Lithium secondary batteries, which are actually used, are manufactured in the order of sealing the electrolyte after filling the electrolyte with the positive electrode, the negative electrode, and the separator wrapped in an outer can. Examples of such a manufacturing method can be found in Japanese Patent Laid-Open No. 98-334884.

The amount of electrolyte required for a lithium ion battery is ideally an amount that adequately fills the pores of the positive electrode, the negative electrode, and the separator, which are porous bodies. By the way, according to the above-described manufacturing method, the electrolyte is filled up to a space irrelevant to the battery function, such as a gap between the outer can and the electrode or a gap between the winding centers possible when the electrode is overlaid. The amount of the electrolyte is much higher than the ideal amount by the electrolyte solution present in the space irrespective of the battery function, which causes a weight increase.

In addition, the electrolyte solution present in the space irrespective of the battery function is more likely to flow out than the electrolyte solution held in the porous body such as an electrode or a separator. Therefore, this may be the cause of the liquid leakage accident of the battery.

As described above, it is preferable to reduce the amount of the electrolytic solution present in the space irrelevant to the battery function from the viewpoint of the weight or the viewpoint of suppressing the liquid leakage accident of the battery.

Summary of the Invention

The present invention has been made to solve the above problems, and an object of the present invention is to manufacture a battery having a very small amount of electrolyte solution present in a space irrelevant to the above-described battery function. MEANS TO SOLVE THE PROBLEM As a result of earnestly researching a battery manufacturing method for the purpose of obtaining a compact, lightweight, high performance battery, it came to complete the battery manufacturing method, battery manufacturing apparatus, and battery which are described below.

The present invention,

(i) a step of filling an electrolyte solution into a power generation element body comprising an anode, a cathode, and a separator, (ii) removing a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution, and (iii) the attached electrolyte solution A battery manufacturing method (claim 1) comprising the step of accommodating a power generation element body from which a portion of the outer container is removed;

A battery manufacturing method according to claim 1 (claim 2) wherein an electrolyte filling step is performed by immersing a power generating element in an electrolyte;

A battery manufacturing method according to claim 1 (claim 3), wherein the process of removing some electrolytes is carried out by applying air flow to the power generation element;

The battery manufacturing method of Claim 3 which applies the airflow blown off from a nozzle to a power generation element body (claim 4);

A battery manufacturing method according to claim 4 (claim 5) for moving a portion to which an air flow is applied to a power generating element body;

A battery manufacturing method (claim 6) according to claim 3, wherein air flow is applied to the power generating element by depressurizing one of the flow paths into which the power generation element is inserted;

The battery manufacturing method of Claim 3 which applies an airflow to a power generating element body by pressurizing one side of the flow path which inserted the power generating element body, and forming airflow (claim 7);

A battery manufacturing method according to claim 1 (claim 8) for removing a part of an electrolyte solution attached to a power generation element by contacting an object having a function of absorbing and retaining an electrolyte solution;

The battery manufacturing method according to claim 1, which further comprises a step of diluting a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution to a liquid compatible with the electrolyte solution while the dissolved solid content is less than that of the electrolyte solution. Range 9);

A battery manufacturing method (claim 10) according to claim 9, wherein the dissolved solid content is less than the electrolyte and the liquid compatible with the electrolyte comprises a solvent constituting the electrolyte;

(i) means for filling an electrolyte solution into a power generation element body comprising an anode, a cathode and a separator, (ii) means for removing a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution, and (iii) the attached electrolyte solution A battery manufacturing apparatus (claim 11), characterized in that it comprises means for accommodating a power generation element body from which a part of the apparatus is removed in an outer container; And

It relates to a battery (claim 12) manufactured according to the battery manufacturing method according to claim 1.

The present invention relates to a method for producing a battery. More specifically, the present invention relates to a method for manufacturing a lithium secondary battery.

BRIEF DESCRIPTION OF THE DRAWINGS In one embodiment of this invention, it is a schematic diagram which shows the process of removing a part of electrolyte solution adhered to a power generating element body by applying the airflow blown off from a nozzle to a power generating element body.

FIG. 2 is a schematic diagram schematically showing the shape of a nozzle having a slit-shaped jet port for generating a strip-shaped air stream applied to a power generating element body in one embodiment of the present invention.

FIG. 3 is a schematic diagram schematically showing the shape of a nozzle having a parallel hole-shaped jet port for generating a band-shaped air stream applied to a power generating element body in one embodiment of the present invention.

4 is a schematic diagram schematically showing a step of removing a part of the electrolyte solution attached to the power generating element by depressurizing one side of the flow path in which the power generating element is inserted in one embodiment of the present invention to form an air flow.

In FIG. 1, (1) is a power generation element body, (2) is a nozzle which blows off gas, and (3) is an airflow.

In FIG. 2, (2) shows a nozzle which blows off gas, (3) shows airflow.

In FIG. 3, (2) shows the nozzle which blows off gas, and (3) shows airflow.

In FIG. 4, (1) is a power generation element body, (3) is airflow, and (4) is a gas flow path.

EMBODIMENT OF THE INVENTION Embodiment of this invention is described below.

The battery manufacturing method of the present invention comprises the steps of: (i) charging an electrolyte solution into a power generation element body comprising an anode, a cathode, and a separator; and (ii) removing a part of the electrolyte solution attached to the power generation element body filled with the electrolyte solution. And (iii) accommodating the power generation element body from which a part of the attached electrolyte solution is removed in an outer container. The contents are explained in full detail below.

The power generating element of the battery is composed of a positive electrode, a negative electrode, and a separator, and there is, for example, a laminate of a positive electrode sheet and a negative electrode sheet and a separator film for separating them. When the overlapped elements are bonded to each other with resin or the like or fixed with tape or the like from the outside, they become power generating elements having independent structures.

As the positive electrode, for example, a poly (vinylidene fluoride) coated with lithium cobalt powder on aluminum foil can be used as a binder. As a negative electrode, what apply | coated and dried graphite carbon powder on copper foil using poly (vinylidene fluoride) as a binder can be used, for example. As the separator, for example, a porous polyethylene film can be used.

The battery functions as the battery when the power generation element having an independent structure is filled with the electrolyte solution. As electrolyte solution, the electrolyte solution which melt | dissolved various electrolyte in arbitrary solvent can be used, for example. As a solvent of electrolyte solution, the mixed solvent of ethylene carbonate and dimethyl carbonate can be used, for example. As the electrolyte, for example, hexafluorophosphate can be used.

The filling of the electrolyte solution may be performed outside of the battery outer container. When the power generation element is relatively large or there is a dense layer on the electrode, it is difficult to efficiently impregnate and fill the electrolyte to the innermost part of the power generation element. If the entire power generation element is decompressed or subjected to centrifugal force in the state of being submerged in the electrolyte, the electrolyte can be efficiently impregnated and filled at a high filling rate. The degree of depressurization can be, for example, a pressure degree slightly higher than the pressure for boiling down the electrolytic solution under reduced pressure. For example, it can be about four times the gravity which is the rotational speed which generates 4G.

When the power generation element filled with the electrolyte solution is taken out of the electrolyte solution, an electrolyte solution (excess electrolyte solution) irrelevant to the battery function is attached to the outside and the winding center. Since this excess electrolyte is a cause of weight increase and liquid leakage, it is desirable to reduce it as much as possible.

By removing a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution, it is possible to reduce the amount of excess electrolyte solution present in the space irrespective of the battery function. By applying airflow to the power generating element body, part of the electrolyte solution attached to the power generating element body can be removed. As the air flow forming gas in the case of removing a part of the electrolyte solution adhered to the power generating element using airflow, dry air and dry nitrogen can be used, for example. Dry air or dry nitrogen does not adversely affect battery performance.

As a method of removing the excess electrolyte, there is a method of blowing a high speed air stream. By applying the airflow blown out from the nozzle to the power generation element, part of the electrolyte solution adhered to the power generation element can be removed. FIG. 1 schematically shows a process of removing a part of the electrolyte solution attached to the power generating element by applying the airflow blown out from the nozzle to the power generating element. When the airflow blown out from the nozzle is sprayed on the surface of the power generating element body, the adhered electrolyte is removed by the pressure.

When applying the airflow ejected from the nozzle to the power generation element, it is possible to efficiently remove the surplus electrolyte solution throughout the power generation element by moving (injecting) a portion having strong force to remove the electrolyte solution, that is, a portion to which the airflow is directly applied. have. When applying the airflow blown out from a nozzle to a power generating element body, it can scan to the site | part to which airflow is directly applied by moving a power generating element body or a nozzle. This operation can be performed at a scanning speed of 5 cm / sec, for example.

It is preferable that the air flow blown out from a nozzle exists in the range of 30-90 degree with respect to the normal line of the electrolyte solution removal surface of a power generating element body. Below 30 °, the flying droplets do not scatter in one direction, increasing the likelihood of contaminating already removed surfaces.

As a nozzle, it is preferable that the strip | belt-shaped airflow blows out from a slit-shaped jet port, and it is preferable to generate | occur | produce strip | belt-shaped airflow from a parallel hole-shaped jet port. A nozzle with a slitted spout is shown schematically in FIG. 2. A nozzle with a parallel hole spout is shown schematically in FIG. 3.

The speed of the air flow blown out from the nozzle can be, for example, about 40 m / sec. When the speed of the air stream blown out from the nozzle is too slow, it is difficult to remove the excess electrolyte sufficiently, and when too fast, the power generating element may be deformed by the pressure of the air stream.

As a method of removing the excess electrolyte solution, there is a method in which the power generating element is disposed in the flow path, and high speed airflow is applied to the flow path. The flow velocity of the airflow flowing in the flow path can be, for example, about 20 m / sec. If the flow rate is too fast, the power generating element tends to deform, and if the flow rate is too slow, it is difficult to remove the excess electrolyte solution sufficiently.

Air can be formed by sending gas from one side of the flow path into which the power generating element body is inserted or by depressurizing one side of the flow path. In FIG. 4, the process of removing one part of the electrolyte solution which adhered to the power generating element body by depressurizing one side of the flow path in which the power generation element body was inserted is formed.

As a method of removing the excess electrolyte, there is a method of contacting with an object having a function of absorbing the electrolyte. As the object having the function of absorbing and retaining the electrolyte, for example, a nonwoven fabric, a woven fabric, a sponge resin, or the like which absorbs the liquid can be used.

By storing the power generating element body from which a part of the adhered electrolyte solution is removed in an outer container, a battery in which a surplus electrolyte solution irrelevant to the battery function is greatly reduced can be formed. As the outer container, for example, a metal can or an aluminum laminated film made of stainless steel or aluminum can be used.

According to the present invention, by reducing the excess electrolyte, the battery can be lightened and the possibility of liquid leakage can be significantly reduced.

When the excess electrolyte is removed, solids in the electrolyte may be remarkably precipitated on the surface of the power generation element depending on the type of electrolyte, due to the evaporation of the solvent. When a battery is manufactured from a power generation element in which solid content is deposited on the surface, irregularities appear on the surface of the outer container, which may lead to an undesirable appearance.

Before or after the process of removing the excess electrolyte solution, a portion of the electrolyte solution attached to the power generating element may be diluted with a liquid (cleaning solution) compatible with the constituents of the electrolyte solution while the dissolved solid content is less than that of the electrolyte solution, thereby reducing the precipitation of solid content. Can be. For example, a part of the electrolyte solution adhered to the power generating element can be diluted by washing the power generating element with the cleaning liquid.

As the cleaning liquid, a liquid in which solid content is not dissolved or a liquid having a small amount of dissolution thereof, for example, a liquid in which solid content is less dissolved than an electrolyte solution can be used, and a liquid having a low influence on battery performance and a liquid compatible with the electrolyte solution can be used. Can be. For example, a solvent in which solutes such as salts are removed from the constituents of the electrolyte solution is not preferable because it does not adversely affect battery performance. As the cleaning liquid, for example, diethyl carbonate, dimethyl carbonate, methylethyl carbonate, propylene carbonate, caprolactone and the like can be used.

Before or after the process of removing the excess electrolyte, the power generation element is washed with such a solvent to prevent precipitation of solids.

According to the battery manufacturing method of the present invention, since the electrolyte solution that does not contribute to the function of the battery is reduced, it is possible to manufacture a battery that is light in weight and prevents leakage of liquid and has no battery performance or appearance problems.

The battery manufacturing apparatus of the present invention includes (i) means for filling an electrolyte solution into a power generation element body comprising an anode, a cathode and a separator, and (ii) means for removing a part of the electrolyte solution attached to the power generation element body filled with the electrolyte solution. And (iii) means for accommodating the power generating element body from which a part of the attached electrolyte solution is removed in an outer container.

The means for filling the power generating element body with the electrolyte has, for example, an electrolyte tank for immersing the power generating element body in the electrolyte solution. As a means for removing a part of the electrolyte solution attached to the power generating element, for example, there are a nozzle for ejecting air flow, a flow path, and a blower or pressure reduction device for forming the air flow, or an object that functions to absorb the electrolyte solution.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

Example 1

(Production of electrolyte)

LiPF ₆ powder was dissolved as a supporting salt in a solvent in which ethylene carbonate and dimethyl carbonate were mixed in a weight ratio of 1: 1, and adjusted to 1 mol / l.

(Production of Electrode)

Cathode active material prepared by mixing 87% by weight of LiCoO _{2 as an} active material, 8% by weight of conductive graphite powder, 5% by weight of poly (vinylidene fluoride) as a binder resin, and N-methylpyrrolidone (hereinafter, NMP) as a solvent. The positive electrode material was manufactured by apply | coating and drying a paste to 200 micrometers in thickness according to the doctor blade method on the collector which consists of aluminum foil of 20 micrometers in thickness, and rolling it to thickness of 120 micrometers further.

Prepared by mixing 95% by weight of mesophase microbeads carbon (manufactured by Osaka Gas Co., Ltd.), 5% by weight of poly (vinylidene fluoride) as a binder resin, and NMP as a solvent. One negative electrode active material paste was applied to a current collector made of copper foil having a thickness of 12 μm and dried by a doctor blade method at a thickness of 200 μm, and further rolled to a thickness of 120 μm to prepare a negative electrode material.

The positive electrode material and the negative electrode material produced as described above were cut into 50 mm x 200 mm to form a positive electrode and a negative electrode, and current collector terminals were mounted at the ends thereof.

(Formation of Power Generation Element)

Insert a separator (CELLGUARD # 2400 made by Hochst Celanese Co., Ltd.) cut between 52 and 210 mm between the positive electrode and the negative electrode, wind it up in an overlapping state, and further press it into a flat wound structure. It fixed with the polyimide adhesive tape. The number of windings was adjusted to a width of about 50 mm when pressed.

(The amount of electrolyte)

The electric power generation element was put into electrolyte solution, the whole was decompressed by the pump, it hold | maintained at 50 torr for 3 minutes, and it returned to normal pressure.

(Removal of excess electrolyte solution)

Electrolyte solution was removed by the airflow which blows out 1 L / sec of dry air in the normal pressure conversion from the slit nozzle of length 70mm width 0.3mm. The angle at which airflow is applied was set at an inclination of 45 ° C from the normal of the power generating element surface, and the distance from the nozzle tip to the power generating element surface was 5 mm. It was removed by scanning at a speed of 5 cm / sec from one end of the power generating element surface to the other end. The above operation was performed on both sides of the power generating element body.

A fine solid precipitate was observed on the surface of the power generation element after the excess electrolyte solution removal operation.

(Exterior by aluminum laminated film)

The power generation element produced by the above process was sealed with an aluminum laminated film under a reduced pressure of about 50 torr to form an exterior.

The aluminum laminated film was cut out to 70 mm x 120 mm and laminated | stacked the aluminum foil of 50 micrometers in thickness, the polyethylene terephthalate film of 12 micrometers in thickness, and the polyethylene film of 5 micrometers in thickness. The film was folded in half to 70 mm x 60 mm, and the remaining three edges were sealed by heat sealing with the power generation element interposed therebetween.

(Evaluation of liquid leak)

A hole having a diameter of 2 mm was drilled at the end of the sheath and held for 5 minutes with the hole downward, and the amount of electrolyte solution leaked from the front and rear weight changes was evaluated.

The weight of the battery manufactured in the above procedure was 13.5 g, and the amount of the effluent liquid by the liquid leak evaluation was 0.05 g.

Example 2 (when placed in euro)

When the battery power generating element was placed therein, a cylindrical flow passage designed to have a clearance of 0.5 mm between the flow path inner wall and the power generating element was manufactured. The power generation element was fixed in this flow path, and dry air was sent to the gap between the flow path and the power generation element to remove excess electrolyte solution. The dry air supply amount was adjusted so that the pressure difference between the upstream side and the downstream side of the power generation element was 0.5 kgf / cm ² .

A battery was manufactured in the same manner as in Example 1 except that the excess electrolyte solution was removed by the above-described method. The weight of this battery was 13.3 g and the amount of effluent according to the liquid leakage evaluation was 0.01 g.

Example 3 (when nonwoven fabric is used)

A battery was prepared in the same manner as in Example 1 except that the excess electrolyte was removed by wiping the electrolyte solution attached to the outside of the power generation element after pouring with a polypropylene nonwoven fabric. The weight of this battery was 13.6 g and the amount of effluent according to the liquid leakage evaluation was 0.07 g. According to this method, a large amount of dry gas supply facilities and the like become unnecessary, but the surplus liquid at the center of the winding structure cannot be removed.

Example 4 (when washing with solvent)

A battery was prepared in the same manner as in Example 1 except that the power generating urea after the electrolyte solution was immediately immersed in diethyl carbonate for 10 seconds and then subjected to a scan for removing the excess electrolyte solution.

The weight of this battery was 13.5 g and the amount of effluent according to the liquid leakage evaluation was 0.05 g. No minute solid precipitate on the surface of the power generating element as observed in Example 1 was observed. Even after sheathing, irregularities caused by solid precipitates did not appear on the surface.

Comparative Example 1

The power generation element was interposed in an aluminum laminate film, sealed with one edge left to form a bag, and an electrolyte solution was injected into the bag-shaped exterior film to carry out reduced pressure impregnation of the electrolyte solution. After impregnation, the excess electrolyte was pipetted out, and the other one was sealed by sealing. A battery was manufactured by the same procedure as in Example 1 except for the above operation. The weight of this battery was 14.1 g and the amount of effluent according to the liquid leakage evaluation was 0.9 g.

As in this comparative example, it is difficult to sufficiently reduce the excess electrolyte that does not contribute to the battery function by an operation of removing the excess electrolyte after exterior. As a result, the weight of the battery becomes heavier, and more electrolyte solution causing liquid leakage also increases.

Comparative Example 2

The power generating element was interposed in an aluminum laminated film to seal the battery with one edge left to form a bag, and an electrolyte solution was injected into the bag-shaped outer film to adjust the weight of the entire battery to be 13.5 g. This weight is the same as Example 1. Thereafter, the mixture was held at 50 torr for 3 minutes, and the other edge was sealed by sealing. A battery was manufactured by the same procedure as in Example 1 except for the above operation.

As described above, the weight of this battery was 13.5 g, and the amount of effluent liquid according to the liquid leakage evaluation was 0.07 g. When the charge and discharge test was conducted at a rate of 0.5C using this battery and the battery of Example 1, the discharge capacity thereof was about 80% as compared with Example 1.

This is because the electrolyte solution is present in the space that does not contribute to the battery performance, resulting in the battery performance can not be sufficiently filled with the electrolyte solution in the required space.

Example 5 (when the air flow is slow)

A battery was manufactured in the same manner as in Example 1 except that the air flow rate was 0.2 L / sec when the excess electrolyte solution was removed. Even after the excess electrolyte removal operation, significant electrolyte residue was observed on the surface of the power generating element. The weight of this battery was 13.9 g, and the amount of the effluent liquid according to the liquid leakage test was 0.5 g. Compared with Example 1, the weight increase due to the excess electrolyte solution and the amount of the electrolyte solution leading to the liquid leakage were observed. The effect was seen.

Comparative Example 4 (when the air flow is fast)

A battery was prepared in the same manner as in Example 1 except that the air flow rate was 2 L / sec when the excess electrolyte was removed.

Peeling between components was observed in the power generation element body after the excess electrolyte solution removal operation partially. The weight of this battery was 13.4 g and the amount of effluent according to the liquid leakage evaluation was 0.02 g.

According to the manufacturing method of Claims 1-8, since there are few extra electrolytes which do not contribute to a battery function, the battery which is lightweight and low liquid leakage possibility can be manufactured.

According to the manufacturing method of Claims 9 and 10, the battery with little unevenness | corrugation which is unpreferable in appearance resulting from the precipitate on the surface of a power generation element can be manufactured.

According to the manufacturing apparatus according to claim 11, it is possible to manufacture a battery which is lightweight and has a low possibility of liquid leakage.

Since the battery of Claim 12 reduces the weight of electrolyte solution, since the weight energy density is high and the extra electrolyte solution is reduced, there is a low possibility of causing a liquid leakage accident.

The battery manufacturing method, battery manufacturing apparatus and battery according to the present invention can be widely applied to a battery composed of a power generation element impregnated with an electrolyte solution such as a lithium ion battery and an outer container for storing the same.

Claims (12)

(i) a step of filling an electrolyte solution into a power generating element body comprising an anode, a cathode, and a separator, (ii) removing a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution, and (iii) storing the power generating element body from which a part of the adhered electrolyte is removed in an outer container; Battery manufacturing method. The method of claim 1, An electrolyte solution filling process is performed by immersing a power generating element in an electrolyte. The method of claim 1, A method of manufacturing a battery, wherein the removing part of the electrolyte is performed by applying airflow to the power generating element. The method of claim 3, wherein A battery manufacturing method which applies the airflow blown out from a nozzle to a power generating element body. The method of claim 4, wherein A battery manufacturing method for moving a portion to which airflow is applied to a power generating element. The method of claim 3, wherein A method for manufacturing a battery in which air flow is applied to a power generation element by depressurizing one side of a flow path in which the power generation element is inserted to form air flow. The method of claim 3, wherein A method of manufacturing a battery in which air flow is applied to a power generating element by pressurizing one side of a flow path into which the power generating element is inserted. The method of claim 1, A battery manufacturing method for removing a portion of an electrolyte solution attached to a power generation element by contacting an object having a function of absorbing an electrolyte solution. The method of claim 1, And diluting a part of the electrolyte solution attached to the power generation element filled with the electrolyte solution to a liquid compatible with the electrolyte solution while the dissolved solid content is less than that of the electrolyte solution. The method of claim 9, A method for producing a battery wherein the dissolved solid content is smaller than the electrolyte and the liquid compatible with the electrolyte constitutes the electrolyte. (i) means for filling an electrolytic solution into a power generating element body in which an anode, a cathode, and a separator are integrally formed; Battery manufacturing apparatus. A battery manufactured according to the battery manufacturing method according to claim 1.