KR20100042429A - Manufacturing method of lithium secondary cell and lithium secondary cell manufactured thereof - Google Patents

Abstract

PURPOSE: A method for manufacturing a lithium secondary cell is provided to reduce manufacturing time of a secondary lithium battery, to lower defective rate in a manufacturing process, and to correspond to the change of the plate size. CONSTITUTION: A method for manufacturing a lithium secondary cell comprises the steps of: forming a negative electrode part by applying a negative active material-containing slurry on a negative electrode current collector; forming a positive electrode part by applying a positive active material-containing slurry on a positive electrode current collector; forming a first cell(700); forming a second cell(800); and repetitively laminating cells.

Description

Manufacturing method of a lithium secondary battery and a lithium secondary battery manufactured by the manufacturing method {Manufacturing Method of Lithium Secondary Cell and Lithium Secondary Cell manufactured}

The present invention relates to a method for manufacturing a lithium secondary battery and a lithium secondary battery manufactured by the method, and more particularly, to shorten the manufacturing time of a lithium secondary battery by improving a method of folding a lithium secondary battery. The present invention relates to a method for producing a lithium secondary battery capable of reducing a defective rate in a manufacturing process, and a lithium secondary battery produced by the method.

A battery is a device that converts chemical energy of an active material contained therein into electrical energy by an electrochemical redox reaction. To this end, the battery has a special structure so that the electrochemical reaction occurs instead of the chemical reaction so that the electrons can escape to the outside through the conductor, and the electron flowing through the conductor becomes an electric energy and is usefully used in our lives.

Today's battery technology has been improved for more than 100 years since the advent of lead-acid batteries in 1860, and the research and development of high output, high performance, light weight, miniaturization, and reliability improvement have progressed greatly. Recently, as miniaturization and light weight of electronic equipment have been realized, and the use of portable electronic devices has become common, research on lithium ion batteries having high energy density has been actively conducted.

The operation principle of a lithium ion battery is prepared by using a material capable of inserting and detaching lithium ions as a cathode part and an anode part, and filling an organic electrolyte or a polymer electrolyte between the anode part and the cathode part, wherein lithium ions are used in the anode part. And electrical energy by oxidation and reduction reactions when inserted and detached from the cathode.

Since such lithium ion batteries are used in a variety of sizes ranging from small cell phone batteries to high capacity electric vehicle batteries, the lithium ion batteries currently distributed in the market range from 1 to 70 cm ² . to be.

Meanwhile, conventional methods of folding a lithium secondary battery include a zig-zag folding method and a stack folding method.

The conventional zigzag method is a method of manufacturing by inserting each electrode into the separation film, so it is difficult to accurately maintain the relative position of the individual electrodes, which is a high possibility of failure due to mismatch of the individual electrodes, Since the separation film must be sandwiched between the individual electrodes, there was a disadvantage that the progress of the process is relatively slow.

The stack folding method is largely divided into a unit cell manufacturing process and a folding process. The unit cell manufacturing process can be performed relatively quickly and has a low defect rate. However, in the folding process, defects are more likely to occur due to mismatches in the position of individual unit cells in the folding process, and in particular, when the area exceeds 60 cm ² , there is a high possibility of defects caused by mismatches during the folding process. Due to this, there is a disadvantage that the progress of the process is relatively slow.

However, in the future, the demand for large-capacity batteries, such as electric vehicles and power tools, is expected to gradually increase. There is a difficult problem.

The present invention has been invented to solve the above problems, a lithium secondary battery that can shorten the manufacturing time of the lithium secondary battery and reduce the defective rate in the manufacturing process by improving the method of folding the lithium secondary battery The purpose of the present invention is to provide a method of manufacturing a lithium secondary battery prepared by the method and the production method thereof.

In the method of manufacturing a lithium secondary battery of the present invention for realizing the above object, a negative electrode active material, a binder, and a conductor are uniformly mixed, dissolved in an organic solvent to form a slurry, and then the slurry is applied to a negative electrode current collector. Thereafter, forming a cathode part through a drying process; Uniformly mixing a positive electrode active material, a binder, and a conductor to make a slurry by dissolving in an organic solvent, applying the slurry to a positive electrode current collector, and then forming a positive electrode part through a drying process; A cathode part, a cathode part, and a separator are sequentially arranged such that a cathode part is positioned at both ends, and at least one anode part and a cathode part are alternately inserted between the cathode parts, and a separator is positioned between the anode parts and the cathode part which are alternately inserted. Forming a first cell by punching the anode part, the cathode part, and the separator from each of the rolls to be bonded to each other in a roll laminator; The anode part, the cathode part, and the separator are sequentially arranged such that an anode part is positioned at both ends, and at least one anode part and a cathode part are alternately inserted between the anode parts, and a separator is located between the alternately inserted anode parts and cathode parts. Forming a second cell by punching the anode part, the cathode part, and the separator from each of the rolls to be bonded to each other in a roll laminator and cutting the roll; After stacking one of the first cell or the second cell on the separator film, the separator film is folded on the stacked cells, the stacked cells and the other cells are stacked, and then the stacked other cells. It characterized in that it comprises the step of laminating by repeatedly performing the process of folding the separator film.

Lithium secondary battery manufactured by the manufacturing method of the present invention for realizing another object is a separate unit, the negative electrode portion is located at both ends and at least one positive electrode portion and the negative electrode portion is inserted between the negative electrode portion and between the positive electrode portion and the negative electrode portion It includes a first cell in which the separator is located; A second cell having an anode unit at each end as an independent unit, at least one anode unit and a cathode unit inserted between the anode units, and a separator located between the anode unit and the cathode unit; And an isolation film enclosing between and outside the at least one first cell and the at least one second cell sequentially arranged.

A method of manufacturing a lithium secondary battery according to the present invention and a lithium secondary battery manufactured by the method according to the present invention use a cell composed of a plurality of positive electrode portions, separators and negative electrode portions in the manufacturing process, i) a relatively high failure rate folding process This simplification reduces the chance of failure, and ii) the manufacturing speed is relatively faster than the conventional folding method.

In addition, since the size of the cell can be changed relatively freely, it is excellent in responding to changes in the size of the electrode plate, and in particular, since there is no separate folding process, the electrode plate can be handled relatively easily even if the area of the electrode plate is increased to 100Cm ² or more.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 3 are independent units according to the present invention, in which a cathode part is positioned at both ends, at least one anode part and a cathode part are inserted between the cathode parts, and a separator is located between the anode part and the cathode part. It is a cross section.

2 and 4 are independent units according to the present invention in which a positive electrode portion is positioned at both ends, and at least one positive electrode portion and a negative electrode portion are inserted between the positive electrode portions, and a separator is positioned between the positive electrode portion and the negative electrode portion. It is a cross section.

As shown in Figure 1 and 2, the lithium ion battery according to the present invention by stacking at least one negative electrode portion 100, the positive electrode portion 200 and the separator 300 inserted therebetween, both ends of the negative electrode portion A first cell 700, which is a cell formed of 100, and a second cell 800, which is a cell formed of an anode part 200, are formed at both ends thereof.

In addition, as shown in FIGS. 3 and 4, a plurality of sequentially stacked forms as described above may be stacked until a desired battery voltage is output. The following describes each part.

The positive electrode unit 200 according to the present invention is composed of a positive electrode mixture 220 including a positive electrode current collector 210 and a positive electrode active material, a conductor, and a binder attached thereto, and the negative electrode unit 100 is a negative electrode current collector. The negative electrode mixture 120 includes a negative electrode active material, a conductor, a binder, and the like attached thereto.

The current collector collects electrons generated by the electrochemical reaction of the active material of the positive electrode or supplies electrons required for the electrochemical reaction. A lithium ion battery generally includes aluminum as the positive electrode current collector 210 and a negative electrode current collector. Copper is used as (110).

The positive electrode active material and the negative electrode active material constituting the negative electrode mixture 120 or the positive electrode mixture 220 are not particularly limited. Generally, the positive electrode active material is LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _4, LiFePO ₄ , LiNi _x Co _y Lithium oxides such as Mn _z O ₂ (where x + y + z = 1) _and Ni-rich compounds are used. Here, Ni-rich compound means a compound represented by Li (Ni _x Co _y Al _z ) O ₂ (where x + y + z = 1). In addition, graphite, natural graphite, artificial graphite, LiTiO ₂ and the like are mainly used as the negative electrode active material.

The conductor is used to improve electron conductivity, and there is no particular limitation, but generally carbon black or acetylene black is used.

The binder is used to fix the positive electrode active material, and polyvinylidene difluoride (PVDF) is generally used.

On the other hand, since the separator 300 should be able to block electron conduction between the anode and the cathode and facilitate lithium ion conduction, a porous material is used. The material of the separator 300 is not particularly limited, and polyolefin-based materials such as polyethylene and polypropylene are mainly used.

Meanwhile, an electrolyte is injected into the separator 300, and the electrolyte serves as a medium for transporting lithium ions required for lithium intercalation between the positive electrode and the negative electrode. The electrolyte is used by dissolving a salt in an organic solvent.

Lithium secondary battery according to the present invention is an independent unit as the above components are located at both ends of the negative electrode portion 100 and between the negative electrode portion 100 at least one positive electrode portion 200 and the negative electrode portion 100 is inserted The anode unit 200 is disposed between the anode unit 200 and the cathode unit 100 as an independent unit from the first cell 700 in which the separator 300 is located, and between the anode unit 200 and the anode unit 200. At least one anode part 200 and the cathode part 100 are inserted, and the second cell 800 in which the separator 200 is positioned is sequentially arranged between the anode part 200 and the cathode part 100, The separator film 400 wraps between and outside the first cell and the second cell.

The material of the isolation film 400 is not particularly limited, and a polyolefin system such as polyethylene and polypropylene is mainly used.

Method of manufacturing a lithium secondary battery according to the present invention comprises the steps of forming the negative electrode unit 100, forming the positive electrode unit 200, forming the first cell 700 and the second cell 800, And disposing the first cell 700 and the second cell 800 on one surface of the separator film 400 and folding the separator film 400.

A negative electrode unit 100 forming step will be described.

The negative electrode active material, the binder, and the conductor are uniformly mixed and dissolved in an organic solvent to form a slurry. After applying the slurry to the negative electrode current collector 110, a negative electrode portion is formed through a drying process. Here, the cathode part 100 has a constant width in the longitudinal direction and is formed long and wound around a roll. In addition, the area of the electrode plate of the negative electrode part is made larger than the electrode plate area of the positive electrode part.

The forming step of the anode part 200 will be described.

The positive electrode active material, the binder, and the conductor are uniformly mixed and dissolved in an organic solvent to form a slurry. After applying the slurry to the positive electrode current collector 210, a positive electrode portion is formed through a drying process. Here, the anode part 100 has a constant width in the longitudinal direction and is formed long and wound around a roll.

A step of forming the first cell 700 will be described.

5 is a view schematically showing a manufacturing process for forming a first cell according to the present invention. First, the cathode part 100, the anode part 200, and the separator 300 formed in the above state are wound by the respective rolls 500, 510, 520, 530... The number of rolls here depends on the capacity of the cells to be stacked. In the present invention, a manufacturing method of the first cell including four separators between at least the cathode portions 100 at both ends of the cell will be described.

As shown in FIG. 5, the uppermost roll has a cathode portion 100 wound thereon, and has a separator 300, an anode portion 200, an isolation membrane 300, an anode portion 100, an isolation membrane 300, and an anode in a downward direction. The portion 200, the isolation layer 300, and the roll on which the cathode portion 100 is wound are disposed sequentially. Next, the cathode 100, the anode 200, and the separator 300 wound on the sequentially placed rules are punched by the punching equipment (not shown) and transferred to the roll laminator 600. Next, after being bonded and cut by the roll laminator 600, a first cell, which is an independent unit, is formed.

Next, the step of forming the second cell 800 will be described.

Since the method of forming the first cell or the second cell differs only in whether both ends are formed of the cathode part 100 or the anode part 200, a description of the method of forming the second cell is omitted here.

Next, the steps of arranging the first cell 700 and the second cell 800 on one surface of the isolation film 400 and a method of folding the isolation film 400 will be described.

After stacking one of the first cell or the second cell on the separator film 400, the separator film is folded on the stacked cells, and then the stacked cells and the other cells are stacked. Repeat the process of folding the isolation film over the other cells to be stacked.

 6 is a view showing an embodiment of a method of manufacturing a secondary battery using a first cell and a second cell manufactured according to the present invention, as shown in FIG. 400, the first cell 700 is placed on the upper surface, the separator film 400 is folded, and the desired cell voltage is repeatedly outputted by repeatedly stacking the second cell 800 on the folded separator upper surface. It shows a method of manufacturing a lithium secondary battery by laminating until it can be.

That is, the isolation film 400 surrounds the outside and at least one of the at least one first cell and the at least one second cell arranged in sequence.

The method for manufacturing a lithium secondary battery according to the present invention can be used for the production of lithium secondary batteries of various sizes ranging from requirements to large capacity, and in particular, it is difficult to produce by a conventional method because it does not undergo a separate folding process. A large area battery of 100 cm ² or more has the advantage that it can be produced with a low failure rate at a faster rate than the conventional method. Herein, the area of the battery means the area of the battery which has been packed, and the large capacity battery in the present invention means a battery having an area of 100 Cm ² or more. However, it is preferable that the area does not exceed 10,000 cm ² . Area If it exceeds 10,000cm ² , the handling becomes busy and the defect rate is high, and there is no economical efficiency due to the facility constraints.

That is, according to the manufacturing method as described above, in the step of manufacturing the first cell and the second cell, there is almost no defective rate in the process, and since the cell composed of a plurality of positive electrode parts and negative electrode parts is used, the number of folding is reduced, thus reducing the manufacturing process time and It can be seen that there is an advantage that can significantly reduce the defective rate.

Although the present invention has been described with reference to a lithium secondary battery, it will be obvious that the present invention can be applied to a lithium ion polymer secondary battery.

Example

1. Make the anode

LiCoO ₂ as a positive electrode active material, carbon black as a conductor, and polyvinylidene difluoride (PVDF) as a binder are uniformly mixed, and then a slurry is prepared using NMP as an organic solvent. The slurry is coated on an aluminum plate, which is a positive electrode current collector, and then dried to prepare a positive electrode.

2. Create cathode

Graphite as a negative electrode active material, carbon black as a conductor, and polyvinylidene fluoride as a binder are uniformly mixed, and then a slurry is prepared using NMP as an organic solvent. The slurry is coated on a copper plate, which is a negative electrode current collector, and then dried to prepare a positive electrode.

3. Create the first cell and the second cell

The cathode part 100 is wound around a roll positioned at the uppermost part and the lowermost part, and two anode parts and one cathode part are alternately inserted between the uppermost part and the lower part, and the separator is positioned between the alternately inserted anode part and the cathode part. The anode part 200, the cathode part 100, and the separator 300 are squeezed from each of the rolls in which the anode part, the cathode part, and the separator are arranged in sequence, are bonded to the roll laminator, and cut and cut into the first cell 700. ).

The second cell 800 is the same as forming the first cell except that the anode part 100 is wound around rolls positioned at the uppermost and lowermost parts.

4. Arrangement and overlap of the first cell and the second cell

By placing the first cell 700 on the top surface of the separator film 400, folding the separator film 400, and repeatedly stacking the second cell 800 on the top surface of the folded separator film, the desired battery voltage is repeatedly used. The lithium secondary battery is manufactured by laminating until it can be output.

It is apparent to those skilled in the art that the present invention is not limited to the above embodiments and can be practiced in various ways without departing from the technical spirit of the present invention. will be.

1 and 2 are independent units according to the present invention, wherein the cathode portions are disposed at both ends thereof, and at least one anode portion and the cathode portion are inserted between the cathode portions, and a separator is disposed between the anode portion and the cathode portion. It is a cross section.

3 and 4 are independent units according to the present invention, in which a positive electrode portion is positioned at both ends, at least one positive electrode portion and a negative electrode portion are inserted between the positive electrode portions, and a separator is positioned between the positive electrode portion and the negative electrode portion. It is a cross section.

5 is a view schematically showing a manufacturing process for forming a first cell according to the present invention.

6 is a view showing an embodiment of a method of manufacturing a secondary battery using a first cell and a second cell manufactured according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: negative electrode 110: negative electrode current collector

120: cathode mixture 200: anode

210: positive electrode collector 220: positive electrode mixture

300: isolation film 400: isolation film

500,510 .... N: Roll which is either anode, cathode or separator

600: roll laminator 700: first cell

800: second cell

Claims (7)

Uniformly mixing the negative electrode active material, the binder, and the conductor to form a slurry by melting in an organic solvent, applying the slurry to the negative electrode current collector, and then forming a negative electrode part through a drying process; Uniformly mixing a positive electrode active material, a binder, and a conductor to make a slurry by dissolving in an organic solvent, applying the slurry to a positive electrode current collector, and then forming a positive electrode part through a drying process; A cathode part, a cathode part, and a separator are sequentially arranged such that a cathode part is positioned at both ends, and at least one anode part and a cathode part are alternately inserted between the cathode parts, and a separator is positioned between the anode parts and the cathode part which are alternately inserted. Forming a first cell by punching the anode part, the cathode part, and the separator from each of the rolls to be bonded to each other in a roll laminator; The anode part, the cathode part, and the separator are sequentially arranged such that an anode part is positioned at both ends, and at least one anode part and a cathode part are alternately inserted between the anode parts, and a separator is located between the alternately inserted anode parts and cathode parts. Forming a second cell by punching the anode part, the cathode part, and the separator from each of the rolls to be bonded to each other in a roll laminator and cutting the roll; After stacking any one of the first cell or the second cell on the separator film, the separator film is folded on the stacked cells, the stacked cells and the other cells are stacked, and then the stacked other cells. Method of manufacturing a lithium secondary battery comprising the step of laminating by repeatedly performing the process of folding the isolation film. The method of claim 1, The negative electrode active material is a graphite, natural graphite, artificial graphite, any one of a lithium secondary battery manufacturing method, characterized in that LiTiO ₂ . The method of claim 1, The cathode active material is LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _4, LiFePO ₄ , LiNi _x Co _y Mn _z O ₂ (where x + y + z = 1) _, Ni-rich, characterized in that any one of the compounds Method of manufacturing a secondary battery. The method of claim 1, The negative electrode current collector is copper, the positive electrode current collector is a method of manufacturing a lithium secondary battery, characterized in that made of aluminum. A large capacity lithium secondary battery having a battery area of 100 Cm ² or more, which is prepared according to any one of claims 1 to 4. A first cell in which a cathode unit is disposed at both ends as an independent unit, at least one anode unit and a cathode unit are inserted between the cathode units, and a separator is located between the anode unit and the cathode unit; A second cell having an anode unit at each end as an independent unit, at least one anode unit and a cathode unit inserted between the anode units, and a separator located between the anode unit and the cathode unit; And Lithium secondary battery comprising an isolation film surrounding the outside and at least one of the at least one first cell and at least one of the second cells arranged in sequence. The method of claim 5, The separator is a lithium secondary battery, characterized in that made of polyethylene or polypropylene.

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