JP2004303560A - Process of manufacture for non-aqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacture for the non-aqueous electrolyte battery achieved with a simpler facility. <P>SOLUTION: The non-aqueous electrolyte battery manufacturing method is provided with an electrolyte body forming process, an electrolyte body inserting process and a non-aqueous electrolyte injecting process. An electrolyte body drying process to dry the electrolyte body by heating the electrolyte body by dielectric heat is provided in between the electrolyte body forming process and the non-aqueous electrolyte injecting process. In the method of manufacture, a battery in which deactivation of active substance due to unevenness in heating is suppressed can be manufactured and the facility can also be simplified since the drying process is simplified. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a non-aqueous electrolyte battery using a non-aqueous electrolyte as an electrolyte.
[0002]
[Prior art]
In recent years, there has been an increasing demand for secondary batteries that can be made lighter and smaller as power sources for driving portable devices. Among these secondary batteries, non-aqueous electrolyte secondary batteries, particularly lithium secondary batteries, have high expectations as batteries having high voltage and high energy density.
[0003]
In general, a lithium secondary battery has a laminated electrode body in which a belt-shaped positive electrode and a band-shaped negative electrode are laminated by winding or the like through a separator made of a porous material, and an electrolytic solution obtained by dissolving an electrolyte in an organic solvent. Is stored in a case.
[0004]
Electrolytes used in non-aqueous electrolyte batteries such as lithium secondary batteries have high reactivity with moisture, so the electrodes and other materials housed in the batteries must be protected from moisture entering the electrolyte. A battery is manufactured after a sufficient drying treatment.
[0005]
Specifically, in a conventional method for manufacturing a nonaqueous electrolyte battery, in order to remove water or suppress re-adsorption to an electrode or the like, at a high temperature before and after processing a positive electrode and a negative electrode to a predetermined thickness and width. A drying process has been performed. After that, it is carried into a drying room such as a dry room, where main processes such as winding, storage in a case, injection of an electrolytic solution, and hermetically sealing the case are performed.
[0006]
In the conventional method of manufacturing a non-aqueous electrolyte battery, not only an expensive dry room facility is required in the manufacturing process, but also the labor required for moisture management in many steps after the electrode is dried has become enormous. In addition, introduction of a heating system into the dry room increases the scale of the dry room, and thus causes a further increase in cost. (For example, see Patent Document 1)
Patent Literature 1 proposes a method of lowering the viscosity by heating when injected into a case because the non-aqueous electrolyte has a higher viscosity than an aqueous solvent-based electrolyte.
[0007]
Specifically, Patent Literature 1 discloses a battery using a positive electrode made of a Li-containing composite oxide and a negative electrode made of a carbonaceous material, in which a strip-shaped positive plate and a strip-shaped negative plate are formed of a porous material. Manufacturing of a non-aqueous electrolyte secondary battery in which a spirally wound electrode group wound through a separator and an electrolyte containing a cyclic ester such as ethylene carbonate in an amount of 30% by weight or more are housed in a battery can. Discloses a method for producing a non-aqueous electrolyte secondary battery, wherein the use of an electrolyte and an electrode group heated to 30 ° C. to 50 ° C. promotes penetration of the electrolyte into the electrode group. Have been.
[0008]
That is, also in this manufacturing method, it is necessary to install the heating equipment in the dry room.
[0009]
[Patent Document 1]
JP-A-10-284121
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a nonaqueous electrolyte battery that can be achieved with simpler equipment.
[0011]
[Means for Solving the Problems]
Means for Solving the Problems The present inventors have conducted intensive studies for the purpose of solving the above problems, and as a result, have made the following inventions.
[0012]
That is, the method for producing a nonaqueous electrolyte battery of the present invention includes a positive electrode having a positive electrode current collector and a positive electrode mixture layer containing a positive electrode active material formed on the positive electrode current collector, a negative electrode current collector, and a negative electrode. A negative electrode having a negative electrode mixture layer containing a negative electrode active material formed on a current collector, and a separator sandwiched between the positive electrode and the negative electrode, an electrode body forming step of forming an electrode body by superimposing, A method for manufacturing a non-aqueous electrolyte battery, comprising: an electrode body insertion step of inserting an electrode body into a case; and a non-aqueous electrolyte solution injection step of injecting a non-aqueous electrolyte solution into the case. An electrode body drying step of heating the electrode body by dielectric heating to dry the electrode body between the step of injecting the nonaqueous electrolyte.
[0013]
That is, the manufacturing method of the non-aqueous electrolyte battery of the present invention, by performing the electrode body drying step after the formation of the electrode body, as in the prior art, a drying step of performing a drying process before and after processing the negative electrode, etc. When forming the dried positive electrode or the like on the electrode body, the step of transporting the dried positive electrode or the like into a drying room such as a dry room can be performed at a time. Furthermore, since the electrode body drying step is performed by dielectric heating, the electrode body can be uniformly heated from inside the electrode body, so that deactivation of the active material due to uneven heating can be suppressed. Therefore, the drying process can be simplified, and the equipment can be simplified.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(Method of manufacturing non-aqueous electrolyte battery)
A method for manufacturing a nonaqueous electrolyte battery according to the present invention includes a positive electrode having a positive electrode current collector and a positive electrode mixture layer containing a positive electrode active material formed on the positive electrode current collector, a negative electrode current collector, and a negative electrode current collector. An electrode body forming step of forming an electrode body by stacking a negative electrode having a negative electrode mixture layer containing a negative electrode active material formed on a body, and a separator sandwiched between the positive electrode and the negative electrode; And a non-aqueous electrolyte injecting step of injecting a non-aqueous electrolyte into the case. That is, a non-aqueous electrolyte battery can be manufactured by applying the method for manufacturing a non-aqueous electrolyte battery of the present invention having these steps.
[0015]
The method for producing a nonaqueous electrolyte battery according to the present invention includes an electrode body drying step of heating the electrode body by dielectric heating and drying the electrode body between the electrode body forming step and the nonaqueous electrolyte injection step.
[0016]
When a voltage is applied to the electrode body in the electrode body drying step, the separator sandwiched between the positive and negative electrode current collectors is polarized into a positive portion and a negative portion, as in a general capacitor. When the polarity of the applied voltage is reversed, the polarization of the separator is also reversed. By changing the polarity of the voltage applied to the electrode body at a rapid cycle, the dipole in the separator is greatly inverted. When the reversal of the dipole is accelerated, a dielectric loss occurs due to resistance of an intermolecular bonding force similar to friction between molecules, and heat is generated. The manufacturing method of the present invention utilizes this heat for drying the electrode body.
[0017]
In general, dielectric heating is capable of rapid heating, excellent heat uniformity due to the heat generated by the insulator separator, high heating efficiency due to excellent energy efficiency, easy temperature control, heating in vacuum, etc. Has features.
[0018]
By performing dielectric heating in the electrode body drying step as described above, the inside of the electrode body can be heated. By heating the wound body of the electrode body from the inside, water present inside the wound body of the electrode body can be easily removed. Furthermore, since dielectric heating can uniformly heat the entire electrode body, heating during drying does not cause uneven heating. As a result, deactivation of the active material due to local overheating can be suppressed.
[0019]
On the other hand, when the electrode body is heated using a heater, the temperature rises from the outer surface of the electrode body, and it takes time for the inside to reach a desired drying temperature. Further, the temperature difference between the inside and the outside surface of the electrode body causes local overheating due to uneven heating, and deactivates the active material of the electrode. The deactivation of the active material causes a decrease in the performance of the electrode body, and as a result, the performance of the nonaqueous electrolyte battery.
[0020]
In the electrode body drying step, it is preferable that heating is performed in a state where the electrode body is inserted in the case. That is, it is possible to save the labor of housing the dried electrode body in the case, and to dry and remove the moisture attached to the inner wall of the case by heating the electrode body by dielectric heating.
[0021]
The electrode body drying step is preferably a step of heating the electrode body under reduced pressure. That is, if the drying is performed under reduced pressure, the drying proceeds rapidly at the same temperature and the drying temperature can be lowered. For this reason, it is possible to prevent the electrode body from overheating due to a decrease in the heating temperature. The lower the reduced pressure when heating the electrode body under reduced pressure, the better. In other words, the lower the pressure, the lower the heating temperature can be, and the overheating of the electrode body can be prevented. More preferably, it is a vacuum atmosphere.
[0022]
In addition, when dielectric heating is performed with the electrode body inserted in the case, the case can be heated under reduced pressure by reducing the pressure in the case. In this case, since only the inside of the case is depressurized, the amount of the atmosphere gas to be removed can be reduced, and the cost required for producing the depressurized atmosphere can be reduced.
[0023]
The dielectric heating preferably energizes the positive electrode and the negative electrode. That is, the positive electrode and the negative electrode can be used as electrodes for causing the separator to generate heat by dielectric heating. Since the positive electrode and the negative electrode are in pressure contact with the separator, the positive electrode and the negative electrode have an effect of efficiently applying a high voltage to the separator. Further, since the positive electrode and the negative electrode are used as electrodes, no new electrodes are required.
[0024]
The dielectric heating is preferably performed by connecting a coil or the like having an inductance to the electrode body in parallel in an electric circuit. By connecting the coil and the like in parallel with the electrode body in an electric circuit manner, it is possible to suppress a noise current flowing in a spike shape in the electrode body with respect to the input voltage. In addition, since the electrode body has the same structure as the capacitor, a heating device with high power efficiency can be provided by using a LC resonance phenomenon by a parallel circuit of a coil and the like and the capacitor.
[0025]
Dielectric heating causes dielectric loss due to the resistance of intermolecular bonding force similar to the friction of molecules when the dipole of the separator sandwiched between the positive electrode and the negative electrode reverses, leading to heat generation, resulting in heat generation. Is more advantageous at high frequencies. When an LC resonance circuit is formed, it is preferable that the inductance be as small as possible and the resonance frequency be as high as possible. The resonance frequency is preferably set in a range from 500 KHz to 40 MHz.
[0026]
In the manufacturing method of the present invention, the frequency of the applied voltage in the dielectric heating is preferably 1 to 100 MHz. By applying a high-frequency current of 1 to 100 MHz, the separator can be heated.
[0027]
The nonaqueous electrolyte battery manufactured by the manufacturing method of the present invention is not particularly limited. That is, the production method of the present invention can be applied to the production of a non-aqueous electrolyte secondary battery having a non-aqueous electrolyte that needs to avoid mixing of water.
[0028]
The method for manufacturing a nonaqueous electrolyte battery according to the present invention will be described based on a method for manufacturing a lithium ion secondary battery. In addition, a figure is a schematic diagram and a dimension, a form, etc. are not exact.
[0029]
A lithium ion secondary battery is a lithium ion secondary battery having a positive electrode having a lithium-metal composite oxide capable of storing and releasing lithium ions as a positive electrode active material as a positive electrode active material layer, and a negative electrode capable of storing and releasing lithium ions. Next battery.
[0030]
The shape of the lithium ion secondary battery manufactured by the manufacturing method of the present invention is not particularly limited, and may be various shapes such as a coin shape, a cylindrical shape, and a square shape. The present embodiment will be described based on a cylindrical lithium ion secondary battery as shown in FIG.
[0031]
FIG. 1 shows a partial cutaway view of a cylindrical lithium ion secondary battery in the present embodiment. The lithium ion secondary battery of the present embodiment has a positive electrode 1 and a negative electrode 2 which are formed in a sheet shape, both of which are stacked with a separator 4 interposed therebetween, and a spirally wound spirally wound electrode body together with an electrolytic solution 3 which fills voids. It is housed in a predetermined cylindrical case 7. The positive electrode 1 and the positive terminal 5 and the negative electrode 2 and the negative terminal 6 are electrically connected to each other.
[0032]
The wound electrode body includes a positive electrode 1, a negative electrode 2, and a separator 4. The positive electrode 1 and the negative electrode 2 are formed in a sheet shape, and both are laminated via the separator 4 and wound in a spiral shape many times.
[0033]
Here, the form of the electrode body of the nonaqueous electrolyte battery is not particularly limited, and in addition to the cylindrical wound electrode body, the square wound electrode body and the electrode are not wound, A stacked electrode body in which a plurality of positive and negative electrodes are stacked via a separator may be used.
[0034]
In the manufacturing method of the present invention, the electrode body forming step is a step of forming an electrode body by superimposing the positive electrode 1, the negative electrode 2, and the separator 4 sandwiched between the positive electrode 1 and the negative electrode 2.
[0035]
Specifically, the end portions of the positive electrode 1, the negative electrode 2, and the separator 4 are attached to a winding core, and the positive electrode 1 and the like are wound around the winding core, whereby a wound electrode body can be formed.
[0036]
In addition, it is necessary to connect the positive electrode terminal 5 and the negative electrode terminal 6 from the positive electrode side and the negative electrode side of the formed electrode body, respectively, but the connection can be made before or after the electrode body forming step. For example, the leads 13 and 23 connected to the terminals 5 and 6 may be connected to the positive electrode 1 and the negative electrode 2 before forming the electrode body, or may be connected during or after forming the electrode body.
[0037]
The positive electrode 1 has, as a positive electrode active material, a lithium-metal composite oxide that can release lithium ions during charging and occlude during discharging. The lithium-metal composite oxide has excellent performance of the active material, such as excellent diffusion performance of electrons and lithium ions. Therefore, when such a composite oxide of lithium and transition metal is used for the positive electrode active material, high charge / discharge efficiency and good cycle characteristics can be obtained. Further, it is preferable that the positive electrode 1 be formed by applying a positive electrode mixture 12 obtained by mixing a positive electrode active material, a conductive material and a binder to a current collector 11.
[0038]
The positive electrode active material is not particularly limited as long as it is a lithium-metal composite oxide, and a known active material can be used. For example, Li _(1-X) NiO ₂ , Li _(1-X) MnO ₂ , Li _(1-X) Mn ₂ O ₄ , Li _(1-X) CoO ₂ And materials to which transition metals such as Li, Al, and Cr are added or substituted. Note that the positive electrode active material is not limited to the case where one kind of substance is used alone, and a plurality of substances may be mixed and used. And X in the example of this positive electrode active material shows the number of 0-1.
[0039]
The material of the negative electrode 2 is not particularly limited as long as it can occlude lithium ions during charging and release lithium ions during discharging, and can use a material having a known material configuration. In particular, it is preferable to use a material obtained by applying a negative electrode mixture 22 obtained by mixing a negative electrode active material, a conductive material and a binder to a current collector 21. The negative electrode active material is not particularly limited by the type of the active material, and a known negative electrode active material can be used. Above all, carbon materials such as natural graphite and artificial graphite having high crystallinity are excellent in active material performance such as excellent in lithium ion occlusion performance and diffusion performance. Therefore, when such a carbon material is used for the negative electrode active material, high charge / discharge efficiency and good cycle characteristics can be obtained. Furthermore, it is more preferable to use lithium metal or a lithium alloy as the negative electrode 2 from the viewpoint of battery capacity.
[0040]
The separator 4 serves to electrically insulate the positive electrode 1 and the negative electrode 2, hold the electrolytic solution 3, and ensure conduction between the positive electrode 1 and the negative electrode 2. It is preferable that the particles have a high property and have intermolecular gaps or pores that do not hinder the permeation of ions.
[0041]
Further, since the calorific value of the dielectric heating is proportional to the tan δ value of the insulator 4 which is an insulator, it is preferable to use a material having as high a tan δ value as possible.
[0042]
Examples of the material used for the separator 4 include polyolefins such as polyethylene, polypropylene, and polymethylpentene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides and polyimides such as polyimide, polyaramid and polyamideimide; polyvinylidene fluoride; Fluororesin such as fluoroethylene, and other polyphenylene ethers, polyphenylene sulfide, polyacetal, polyarylate, polycarbonate, polyether sulfone, polyether ether ketone, and the like.A single separator of these, or a composite separator may be used. . Thus, it is preferable to use a resin having a melting point of 100 ° C. or more, which is the boiling point of water.
[0043]
It is preferable that the separator 4 be larger than the positive electrode 1 and the negative electrode 2 in order to ensure the insulation between the positive electrode 1 and the negative electrode 2 more reliably.
[0044]
The electrode body drying step is a step of heating the electrode body by dielectric heating to remove moisture inside the electrode body. The electrode body generates heat in the electrode body drying step, so that a dried electrode body is obtained.
[0045]
The electrode body inserting step is a step of inserting the electrode body into the case 7.
[0046]
The shape and material of the case 7 are not particularly limited in applying the present invention. In general, cylindrical and square shapes are well known. Further, the material of the case 7 needs to be a material which is electrochemically stable in relation to the electrolyte 3 as a nonaqueous electrolyte inside. As the material of the case 7, a commonly used material such as a nickel-plated steel plate, aluminum, aluminum laminate, or resin can be selected.
[0047]
The gasket 72 is sandwiched between the case 7, the lid 71 and the positive and negative terminals 5, 6 in order to maintain the hermeticity, insulation and the like of the case 7. The gasket 72 secures electrical insulation between the case and the terminal portions 5 and 6, and sealability in the case 7. The gasket 72 can be made of, for example, a polymer such as polypropylene which is chemically and electrically stable with respect to the electrolyte 3.
[0048]
The non-aqueous electrolyte injection step is a step of injecting the electrolyte 3 as a non-aqueous electrolyte into the case 7.
[0049]
The electrolytic solution 3 is obtained by dissolving an electrolyte in an organic solvent.
[0050]
The organic solvent is not particularly limited as long as it is an organic solvent usually used for an electrolyte of a lithium ion secondary battery, and examples thereof include a carbonate compound, a lactone compound, an ether compound, a sulfolane compound, a dioxolan compound, a ketone compound, and a nitrile. And halogenated hydrocarbon compounds.
[0051]
Specifically, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol dimethyl carbonate, propylene glycol dimethyl carbonate, ethylene glycol diethyl carbonate, carbonates such as vinylene carbonate, lactones such as γ-butyl lactone Ethers such as dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran and 1,4-dioxane; sulfolane such as sulfolane and 3-methylsulfolane; dioxolanes such as 1.3-dioxolane; 4-methyl- Ketones such as 2-pentanone; nitriles such as acetonitrile, piropionitrile, pareronitrile, and benzonitrile; Halogenated hydrocarbons such as chloroethane, and other methyl formate, dimethylformamide, dimethylformamide, dimethyl sulfoxide, and the like, and these alone or as a mixture of a plurality of organic solvents selected therefrom, Is also good.
[0052]
Among these organic solvents mentioned in the examples, in particular, by using one or more nonaqueous solvents selected from the group consisting of carbonates and ethers, the solubility of the electrolyte, the dielectric constant and the viscosity are excellent, It is preferable because the charge and discharge efficiency is high. Further, those having a high flash point are preferable from the viewpoint of easiness in injecting an electrolytic solution described later. In particular, it is preferable to use an electrolyte having a flash point of 70 ° C. or higher. The flash point can be improved by, for example, mixing a phosphate ester.
[0053]
The type of the electrolyte is not particularly limited, but may be LiPF. ₆ , LiBF ₄ , LiClO ₄ And LiAsF ₆ An inorganic salt selected from the group consisting of ₃ CF ₃ , LiC (SO ₃ CF ₃ ) ₂ And LiN (SO ₃ CF ₃ ) ₃ And at least one of organic salt derivatives and derivatives of the organic salt.
[0054]
With this electrolyte, the battery performance can be further improved, and the battery performance can be maintained even higher in a temperature range other than room temperature.
[0055]
The concentration of the electrolyte is also not particularly limited, and it is preferable to appropriately select the concentration in consideration of the type of the electrolyte and the organic solvent depending on the application.
[0056]
Further, in the production method of the present invention, it is preferable that the non-aqueous electrolyte injection step is performed after the temperature of the electrode body is cooled to a predetermined temperature. Since the viscosity of the electrolyte 3 decreases as the temperature increases, the injection of the electrolyte 3 at a high temperature allows the electrolyte 3 to penetrate into the case 7 and the electrode body more quickly. Here, the predetermined temperature is not particularly limited, but is preferably as high as possible from the viewpoint of lowering the viscosity of the electrolyte 3. However, if the temperature is too high and the flash point is higher than the flash point of the organic solvent used for the electrolytic solution 3, it is necessary to invest in equipment for preventing ignition. Therefore, the flash point is preferably lower than the flash point of the organic solvent used. For example, when ethylene carbonate or diethylene carbonate is used as the organic solvent, the temperature is preferably 70 ° C. or lower.
[0057]
(Electrode body drying device)
In the manufacturing method of the present invention, the electrode drying device for heating the electrode body, the positive electrode, the negative electrode, the electrode body formed by superimposing the separator sandwiched between the positive electrode and the negative electrode dielectric heating. To heat and dry the electrode body. That is, by heating the electrode body by dielectric heating, moisture remaining inside the electrode body can be removed from the electrode body.
[0058]
The electrode body drying device has a terminal connection part connected to a terminal part of the electrode body to be dried, a coil connected in parallel with the electrode body in an electric circuit, and supplies a high-frequency current to the parallel circuit. Configuration. The coil and the like have a role of removing noise and forming an LC resonance circuit between the coil and the like and the electrode body. By supplying a high-frequency voltage, molecular friction occurs due to reversal of the polarization of the separator, which is a dielectric, and the separator is heated. Therefore, the temperature of the electrode body can be increased by dielectric heating.
[0059]
It is necessary to reduce the contact area of the terminal connection portion connecting the electrode body and the circuit, and to suppress Joule heat generation at the terminal portion. In addition, since the high-frequency current has a small penetration depth and flows on the surface of the terminal connection portion, it is preferable that the terminal connection portion be made of a copper plate or the like to minimize the resistance.
[0060]
It is preferable to have a pressure reducing means for reducing the atmosphere of the electrode body. By having the decompression means, the heating humidity when heating and drying the electrode body can be reduced. By reducing the heating temperature, deactivation of the active material due to overheating can be suppressed.
[0061]
It is preferable that the electrode body is installed in the electrode body drying device while being housed in the case. That is, it is possible to save time and effort for housing the dried electrode body in the case, and to dry and remove moisture attached to the inner wall of the case by heating the electrode body by dielectric heating.
[0062]
It is preferable to have a control means for adjusting a high-frequency current supplied to a circuit including an electrode body and a coil. By having the control means, the temperature rise due to the high-frequency current can be controlled, and the drying of the electrode body can be made the optimum condition.
Since the electrode body drying apparatus of the present invention applies a high-frequency current directly to the terminal portion of the electrode body, the electrode body of the conventional lithium battery can be quickly and uniformly heated even in a vacuum. In a conventional drying oven, drying is performed only by radiant heat in a vacuum, and it takes a long time to raise the temperature.
[0063]
【Example】
Hereinafter, the present invention will be described using examples.
[0064]
(Example 1)
As an example of the present invention, a device for drying an electrode body was manufactured, and a lithium battery was manufactured using the device for drying an electrode body.
[0065]
(Electrode body drying device)
The electrode body drying apparatus of the present embodiment is a dielectric heating apparatus whose main configuration is shown in FIG.
[0066]
The electrode body drying device 9 includes a power supply unit 91, a transformer unit 92 electrically connected to the power supply unit 91 and amplifying the power of the power supply unit 91, a circuit unit 93 electrically connected to the transformer unit 92 and a battery, It has a battery connected to the circuit section 93 and a coil 94 connected in parallel in an electric circuit.
[0067]
The power supply unit 91 has a transformer therein, and amplifies the current input by the transformer 12 times. Then, the transformer unit 92 amplifies the current value from the power supply unit six times.
[0068]
Therefore, the supply current supplied from the transformer unit to the circuit unit is 72 times the input current of the power supply.
[0069]
The coil had an inductance of 347 nH.
[0070]
Note that the drying apparatus of this embodiment has a vacuum pump (not shown) for reducing the pressure inside the battery case. The vacuum pump is connected to the electrolyte injection opening 711 for injecting the electrolyte 3 into the battery case 7 and discharges air from the battery case 7. In order to measure the current flowing in the circuit, a sensor (not shown) was installed in the circuit.
[0071]
(Manufacture of lithium ion secondary batteries)
The lithium ion secondary battery shown in FIG. 1 was manufactured as follows.
[0072]
A paste formed by kneading 85 parts by weight of lithium manganate as an active material, 10 parts by weight of acetylene black as a conductive material, and 5 parts by weight of polyvinylidene fluoride as a binder, is formed into a paste-like mixture. The positive electrode plate 1 in which the positive electrode mixture layer 12 was formed on the positive electrode current collector 11 was manufactured by applying and compressing both surfaces of a 15 μm aluminum foil current collector 11.
[0073]
Subsequently, a base mixture obtained by kneading 92.5 parts by weight of carbon as an active material and 7.5 parts by weight of polyvinylidene fluoride as a binder was collected into a 10 μm-thick copper foil collection. The negative electrode plate 2 having the negative electrode current collector 21 and the negative electrode mixture layer 22 formed on the negative electrode current collector 21 was manufactured by applying and pressing the both surfaces of the current collector 21.
[0074]
Each of the positive electrode plate 1 and the negative electrode plate 2 has uncoated portions 111 and 211 on which the mixture is not applied, and the surface of the uncoated portion 111 of the current collector 11 of the positive electrode 1 has a plurality of aluminum. And a plurality of copper leads 23 on the surface of the uncoated portion 211 of the current collector 21 of the negative electrode 2 for extracting current from the electrode plate to the positive terminal 5 and the negative terminal 6, respectively. Joined by sonic welding.
[0075]
Next, between the positive electrode plate 1 and the negative electrode plate 2, a separator 4 that is cut so as to be wide so that the positive electrode plate 1 and the negative electrode plate 2 do not directly contact with each other is spirally wound to form a spirally wound electrode body. Was prepared. At this time, a film in which a porous polypropylene film and a porous polyethylene film were combined was used as the separator 4.
[0076]
Subsequently, the leads 13 and 23 attached to the positive electrode plate 1 and the negative electrode plate 2 are subjected to convergence processing, joined to the positive electrode terminal portion 5 and the negative electrode terminal portion 6 by ultrasonic welding, respectively, and then stored in the battery case 7 and The terminal portion 5 and the lid plate 71, and the negative electrode terminal portion 6 and the battery case 7 were joined by a laser welding method under welding conditions for maintaining airtightness and liquid tightness. In addition, the battery case 7 is formed of a Ni-plated steel plate.
[0077]
The capacitance of the lithium ion secondary battery of this example at the stage manufactured as described above was 0.03 μF.
[0078]
The battery housing the electrode body in the battery case 7 was arranged at a predetermined position of the electrode body drying device, and was electrically connected to the circuit unit 93. At this time, the battery was placed in a state where the electrolyte injection opening 711 of the battery case 7 was connected to the vacuum pump. Thereafter, the vacuum pump was operated to reduce the pressure inside the battery case 7 to 133 Pa. With the pressure inside the battery case 7 reduced, the power switch of the electrode body drying device was turned on, and a high-frequency current was supplied to the circuit unit 93. The frequency of the high-frequency current at this time was set to 1.3 MHz, the voltage was set to 100 V, and the current was set to 10 A. The current value flowing through the electrode body and the coil was 720A.
[0079]
When a high frequency current was applied to the battery, the dielectric separator generated heat. Using a thermocouple attached to the axis of the winding axis of the electrode body and the outer peripheral surface of the battery case 7 beforehand, the respective temperatures were measured. The temperature of the outer peripheral surface of the battery case 7 rose. Thereafter, the temperature was maintained by adjusting the applied current applied to the battery. The moisture present inside the battery case 7 was vaporized by holding at a high temperature under reduced pressure, and was discharged to the outside by a vacuum pump.
[0080]
Then, when one minute had elapsed after the holding, the amount of water in the exhaust from the battery case 7 by the vacuum pump became 2500 ppm or less. Then, the high-frequency current was cut off (the power switch was turned off), and the heating was terminated.
[0081]
After allowing to cool, the battery was removed from the electrode body drying device.
[0082]
Thereafter, the opening 711 for injecting the electrolyte, which was previously set on the lid 71, was temporarily sealed with a sealing part made of EPDM. After being transported to the electrolytic solution injecting device while being temporarily sealed with the sealing component, the sealing component was removed, and then a non-aqueous electrolytic solution was injected through the electrolytic solution injecting opening 711 of the lid 71. As the non-aqueous electrolyte, a solution prepared by dissolving lithium hexafluorophosphate in a solvent in which ethylene carbonate and diethylene carbonate were mixed at a weight ratio of 3: 7 was used.
[0083]
After injecting a predetermined amount of the electrolytic solution, the injection opening 711 was hermetically and liquid-tightly sealed with a sealing plug 74.
[0084]
By the above means, the lithium ion secondary battery of Example 1 was manufactured.
[0085]
(Example 2)
A lithium secondary battery was manufactured in the same manner as in Example 1 except that drying conditions by dielectric heating were different.
[0086]
Drying in this example was performed by performing dielectric heating at a high-frequency current frequency of 1.3 MHz, a voltage of 50 V, and a current of 5 A (the current flowing through the electrode body and the coil was 360 A).
[0087]
In this example, it took 2 minutes and 12 seconds to reach 120 ° C. during drying.
[0088]
(Example 3)
A large battery having a capacitance of 0.25 μF at the stage before the electrolyte was injected was manufactured. In this example, a battery was manufactured in the same manner as in Example 1 except that drying conditions by dielectric heating were different.
[0089]
Drying in this example was performed by performing dielectric heating at a frequency of a high-frequency current of 540 kHz, a voltage of 100 V, and a current of 10 A (the current flowing through the electrode body and the coil was 720 A).
[0090]
In this example, it took 12 minutes and 40 seconds to reach 90 ° C.
[0091]
(Example 4)
A lithium secondary battery was manufactured in the same manner as in Example 3, except that a drying device having a coil of 100 nH was used. In this example, drying by dielectric heating was performed in the same manner as in Example 1.
[0092]
In this embodiment, it took 6 minutes to reach 80 ° C.
[0093]
(Example 5)
A lithium secondary battery was manufactured in the same manner as in Example 4, except that drying conditions by dielectric heating were different.
[0094]
Drying in this example was performed by performing dielectric heating at a frequency of a high-frequency current of 1.3 MHz, a voltage of 150 V, and a current of 15 A (the current flowing through the electrode body and the coil was 360 A).
[0095]
In this embodiment, it took 2 minutes and 25 seconds to reach 110 ° C.
[0096]
(Comparative example)
In this comparative example, a lithium secondary battery was manufactured in the same manner as in Example 1 except that drying was performed by holding the battery in a vacuum oven.
[0097]
In this comparative example, it took 26 minutes for the battery internal temperature to reach 120 ° C. In addition, it took 11 minutes for the outer peripheral portion of the battery to reach 120 ° C.
[0098]
That is, the lithium secondary battery manufactured in this comparative example had different temperature histories at the outer peripheral portion and the central portion.
[0099]
(Evaluation)
From the above Examples and Comparative Examples, in each Example, the heating time in the drying step before injecting the electrolytic solution is significantly shorter than in the Comparative Examples. That is, by using the manufacturing method of the present invention, the time required for manufacturing the lithium secondary battery can be reduced, and the manufacturing cost can be reduced.
[0100]
Further, in each of the embodiments, since the heating is performed uniformly by the dielectric heating, the temperature history of the electrode body does not become uneven. That is, in the lithium secondary battery manufactured by using the manufacturing method of the present invention, since the deactivation of the active material due to local overheating caused by uneven heating is suppressed, the battery performance is suppressed from deteriorating. It has become.
[0101]
As described above, by using the manufacturing method of the present invention, in each of the examples, it was possible to easily manufacture a lithium secondary battery having high battery characteristics.
[0102]
【The invention's effect】
In the method for manufacturing a nonaqueous electrolyte battery according to the present invention, drying is performed by heat generated by the electrode body due to dielectric heating. That is, by causing the separator of the electrode body to generate heat, moisture existing inside the electrode body can be easily removed. Further, the dielectric heating can uniformly heat the entire electrode body. That is, since heating unevenness during heating during drying is eliminated, deactivation of the active material due to local overheating can be suppressed. As a result, the manufacturing method of the present invention has an effect that a nonaqueous electrolyte battery having high battery characteristics can be manufactured with a simple device.
[Brief description of the drawings]
FIG. 1 is a partially cutaway view showing the overall configuration of a cylindrical lithium ion secondary battery.
FIG. 2 is a diagram showing a configuration of an electrode body drying apparatus.
[Explanation of symbols]
1: positive electrode 11: positive electrode current collector
111: uncoated portion 12: positive electrode mixture layer 13: positive electrode lead
2: negative electrode 21: negative electrode current collector
211: uncoated portion 22: negative electrode mixture layer 23: negative electrode lead
3: Non-aqueous electrolyte 4: Separator 5: Positive electrode terminal
6: negative electrode terminal 7: case 71: cover plate
711: Injection opening 72: Gasket 73: Nut
74: sealing plug 9: electrode body drying device 91: power supply unit
92: Transformer 93: Circuit 94: Coil

Claims (4)

A positive electrode having a positive electrode current collector and a positive electrode mixture layer containing a positive electrode active material formed on the positive electrode current collector, a negative electrode current collector, and a negative electrode active material formed on the negative electrode current collector; A negative electrode having a negative electrode mixture layer, a separator sandwiched between the positive electrode and the negative electrode, and an electrode body forming step of forming an electrode body by superimposing,
An electrode body insertion step of inserting the electrode body into a case,
A non-aqueous electrolyte injection step of injecting a non-aqueous electrolyte into the case,
A method for producing a non-aqueous electrolyte battery having
A non-aqueous electrolyte battery, comprising: an electrode body drying step of heating the electrode body by dielectric heating to dry the electrode body, between the electrode body forming step and the non-aqueous electrolyte injecting step. Production method. The method for manufacturing a nonaqueous electrolyte battery according to claim 1, wherein in the electrode body drying step, heating is performed in a state where the electrode body is inserted into the case. The method for manufacturing a nonaqueous electrolyte battery according to claim 1, wherein the electrode body drying step is a step of heating the electrode body under reduced pressure. The method for manufacturing a nonaqueous electrolyte battery according to claim 1, wherein the dielectric heating energizes the positive electrode and the negative electrode.

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