KR100714128B1 - Rechargeable battery having non-metallic current collector and method of manufacturing the same - Google Patents

Abstract

Disclosed is a lithium secondary battery including a nonmetallic current collector including a nonmetallic conductive layer and a method of manufacturing the same. The lithium secondary battery according to the present invention includes a first nonmetal current collector composed of a first polymer film and a first nonmetal conductive layer, and a first electrode layer formed on the first nonmetal conductive layer. In addition, a second non-metallic current collector composed of a second polymer film and a second non-metal conductive layer, and a second electrode layer formed on the second non-metal conductive layer. A polymer electrolyte layer containing an organic electrolyte is formed between the first electrode layer and the second electrode layer. By using a nonmetallic current collector manufactured by depositing or laminating a nonmetallic conductive layer in a thin film form on a thin polymer film, an ultra-thin lightest lithium secondary battery having minimal use of metal is realized.

Nonmetallic Conductive Layer, Nonmetallic Current Collector, Polymer Electrolyte, Organic Electrolyte

Description

Lithium secondary battery having a non-metallic current collector and a method of manufacturing the same {Rechargeable battery having non-metallic current collector and method of manufacturing the same}

1 is a view schematically showing the structure of a lithium secondary battery according to a preferred embodiment of the present invention.

2 is a flowchart illustrating a method of manufacturing a lithium secondary battery according to a preferred embodiment of the present invention.

3 is a graph showing charge and discharge characteristics of a lithium secondary battery unit cell manufactured by the method according to the present invention.

4 is a graph evaluating the cycle stability of the lithium secondary battery unit cell manufactured by the method according to the present invention.

5 is a graph showing energy density values per weight and volume of a lithium secondary battery manufactured by the method according to the present invention.

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

10: first nonmetal current collector, 12: first polymer film, 14: first nonmetal conductive layer, 16: anode layer, 20: second nonmetal current collector, 22: second polymer film, 24: second nonmetal conductive layer , 26: negative electrode layer, 30: polymer electrolyte layer, 100: lithium secondary battery.

The present invention relates to a lithium secondary battery and a method for manufacturing the same, and more particularly, to a lithium secondary battery having a polymer current collector and a method for manufacturing the same.

Recently, thanks to the rapid development of DMB (Digital Multimedia Broadcasting) technology and next-generation PC technology, mobile DMB phones have been commercialized, and watch-type or wearable PC prototypes are being released one after another. In addition, the existing portable electronic devices are becoming more and more versatile and converged, such as mobile phones, video calls, MP3 players, personal digital assistants (PDAs), digital cameras, voice pens, electronic notebooks, and HDDs (hard disk drives). You have everything. However, while miniaturization, thinning, and lightening of electronic devices are rapidly progressing, power supply elements for driving them do not meet their requirements. This is because, compared with the speed of miniaturization and high performance of the terminal, the limit of material and process conditions in the power supply system has already reached the limit in increasing the energy density of the power supply device. Therefore, there is an urgent need for high energy density and high output through the development of new materials and new concept process systems that can overcome these limitations.

Representative examples of power devices that have been applied to DMB and next-generation PCs are lithium ion batteries or lithium ion polymer batteries. These lithium secondary batteries include a positive electrode or a negative electrode manufactured by using a material capable of inserting and detaching lithium ions as an active material, and an organic electrolyte or a polymer electrolyte capable of moving lithium ions is inserted between the positive electrode and the negative electrode. Here, in the case of the positive electrode, the active material is coated on the aluminum current collector, and in the case of the negative electrode, the active material is coated. Each of the negative electrode, the electrolyte, and the positive electrode thus prepared is laminated and finally sealed with a stainless steel can or an aluminum pouch. do. To date, steady process improvements have increased the energy density by more than 10% annually.

However, as a result of focusing on the improvement of the filling density without a large change in the active material and the constituent material, the increase in energy density per weight reaches its limit, and as the energy in the cell increases, the stability gradually decreases. Therefore, the development of new constituent materials and manufacturing process that can further improve the weight and stability of the material at the same time is urgently needed.

In addition, since lithium secondary battery materials such as active materials, binders, separators, current collectors, and packaging materials, except for electrolytes, are mostly dependent on imports, a drop in battery prices due to competition is a fundamental cause of direct profitability deterioration. In particular, in the case of using a copper and aluminum current collector, there is a limit on the maximum radius of curvature that can be obtained during winding due to the metal property, and thus, there is a limit on volume reduction. It is urgent to develop a low-cost, light weight non-metallic current collector or a current collector in which the use of metal is minimized by replacing the current collector.

The present invention is to solve the above problems in the prior art, it is possible to reduce the weight of the lithium secondary battery, has improved flexibility to improve the filling density during winding, increase the energy density per weight and volume and cycle stability It is to provide a lithium secondary battery that can be improved.

Another object of the present invention is to provide a method for manufacturing a lithium secondary battery that is simple, easy, and relatively easy to fabricate, thereby applying a fully relaxed process condition, which facilitates a completely continuous process and mass production, and can lower manufacturing costs.

In order to achieve the above object, a lithium secondary battery according to the present invention is a first non-metal current collector composed of a first polymer film and a first non-metal conductive layer, a first electrode layer formed on the first non-metal conductive layer, and a second A second nonmetal current collector comprising a polymer film and a second nonmetal conductive layer, a second electrode layer formed on the second nonmetal conductive layer, and formed between the first electrode layer and the second electrode layer and including an organic electrolyte solution. It includes a polymer electrolyte layer.

The first polymer film and the second polymer film may be each made of a polyester polymer, a polyolefin polymer, a cellulose polymer, nylon, polyimide, or a combination thereof. In addition, the first polymer film and the second polymer film may each have a single layer or a multilayer structure made of a single kind of polymer material, or a multilayer structure including at least two kinds of different polymer materials.

The first nonmetal conductive layer and the second nonmetal conductive layer may be formed of a carbon nanotube paste coating layer, a nanoparticle conductive carbon paste coating layer, a nanoparticle metal paste coating layer, a conductive polymer coating layer, or an ITO paste coating layer, respectively. The first non-metal conductive layer and the second non-metal conductive layer may each have a thickness of about 10 μm to about 50 μm.

In a lithium secondary battery according to an embodiment of the present invention, the first electrode layer is made of a mixture of a first conductive agent, a first polymer binder, and a positive electrode active material, and the second electrode layer is a second conductive agent, a second polymer binder. It may be made of a mixture of the agent and the negative electrode active material.

In a lithium secondary battery according to another embodiment of the present invention, the first electrode layer may be made of a mixture of a first conductive agent, a first polymer binder, and a positive electrode active material, and the second electrode layer may be made of lithium metal.

The polymer electrolyte layer may be formed of a polymer film containing an organic electrolyte solution containing a lithium salt. In particular, the polymer electrolyte layer may include an organic electrolyte solution containing a polymer matrix, an inorganic additive, and a lithium salt.

The polymer matrix is polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyl chloride, polystyrene, polyethylene oxide, polypropylene oxide, polybutadiene, cellulose, carboxymethylcellulose, nylon, polyacrylonitrile, polyvinylidene Fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trifluoroethylene, copolymer of vinylidene fluoride and tetrafluoroethylene, polymethyl Any one selected from the group consisting of acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyvinylacetate, polyethylene oxide, and polypropylene oxide of It may be made of a polymer, or a blend thereof.

The inorganic additive may be made of at least one material selected from the group consisting of silica, talc, alumina (Al ₂ O ₃ ), TiO ₂ , clay, and zeolite.

The organic electrolyte is ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, methyl formate, ethyl formate, and gamma-butyrolactone It may be made of any one selected from the group consisting of, or a mixture thereof.

The lithium salt may be lithium perchlorate (LiClO ₄ ), lithium triplate (LiCF ₃ SO ₃ ), lithium hexafluorophosphate (LiPF ₆ ), lithium iodide (LiI), lithium tetrafluoroborate (LiBF ₄ ), and At least one selected from the group consisting of lithium trifluoromethanesulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ).

In order to achieve the above another object, in the method of manufacturing a lithium secondary battery according to the present invention, a first polymer film and a second polymer film are prepared. A first nonmetallic conductive layer is formed on the first polymer film to form a first nonmetallic current collector. A second nonmetal conductive layer is formed on the second polymer film to form a second nonmetal current collector. A first electrode layer is formed on the first nonmetal current collector. A second electrode layer is formed on the second nonmetal current collector. A polymer electrolyte layer including an organic electrolyte is formed between the first electrode layer and the second electrode layer.

Forming the first non-metallic current collector may include coating carbon nanotube paste, nanoparticle conductive carbon paste, nanoparticle metal paste, conductive polymer, or ITO paste on the first polymer film. In addition, the forming of the second non-metallic current collector may include coating carbon nanotube paste, nanoparticle conductive carbon paste, nanoparticle metal paste, conductive polymer, or ITO paste on the second polymer film. .

The lithium secondary battery according to the present invention can be easily applied to a wearable PC or the like since it is possible to implement a battery that can be rolled or bent like a roll. In addition, it exhibits excellent filling density characteristics by minimizing the radius and volume of the battery implementation by lamination and winding, and can achieve improved results in energy density per weight. According to the method of manufacturing a lithium secondary battery according to the present invention, the process conditions such as tension during continuous production is also significantly reduced compared to when using a conventional metal current collector, it is easy to mass the cells.

Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the structure of a lithium secondary battery 100 according to a preferred embodiment of the present invention.

Referring to FIG. 1, the all-solid-state lithium secondary battery 100 according to the present invention includes a first nonmetallic current collector 10 and a second nonmetallic current collector 20.

The first nonmetal current collector 10 is composed of a first polymer film 12 and a first nonmetal conductive layer 14. The second nonmetal current collector 20 is composed of a second polymer film 22 and a second nonmetal conductive layer 24.

The first polymer film 12 and the second polymer film 22 serve to prevent moisture and oxygen permeation into the battery, respectively. The first polymer film 12 and the second polymer film 22 may each include a polyester-based polymer such as polyethylene terephthalate, polybutylene terephthalate, etc. according to characteristics such as mechanical strength, moisture and oxygen permeability; Polyolefin-based polymers such as polyethylene and polypropylene; Cellulose polymers; nylon; Polyimide; Or it may be formed by laminating a polymer film made of a combination of these in a single layer or multiple layers. Alternatively, the first polymer film 12 and the second polymer film 22 may be formed by laminating a multilayer film by combining a polyester polymer film and a polyolefin polymer film, respectively. The first polymer film 12 and the second polymer film 22 may each have a thickness of about 5 to 100 μm.

The first non-metal conductive layer 14 and the second non-metal conductive layer 24 may be formed on one side of the first polymer film 12 and the second polymer film 22. It may be formed by coating nanoparticle metal paste, conductive polymer, or ITO (indium tin oxide) paste. The term "nanoparticle" as used herein refers to particles having a particle size of several tens to tens of nanometers.

The first nonmetallic conductive layer 14 and the second nonmetallic conductive layer 24 may each have a thickness of about 10 μm to 50 μm, preferably about 5 to 150 μm.

Since the first non-metallic current collector 10 and the second non-metallic current collector 20 contain almost no metals, the existing non-metal current collectors 10 and the second non-metallic current collectors 20 substantially change existing process conditions in the manufacturing process compared with the case of the metal current collector according to the prior art. The thickness of the current collector can be made even thinner and the weight can be greatly reduced without the need for this. In addition, by using the first polymer film 12 and the second polymer film 22, the bending characteristics are very excellent, there is no folding phenomenon, and it is easy to manufacture a sealed battery.

An anode layer 16 is coated on the first nonmetallic current collector 10, and a cathode layer 26 is coated on the second nonmetallic current collector 20.

The positive electrode layer 16 may be formed by coating a slurry including a mixture of a conductive agent, a polymer binder, and a positive electrode active material on the first non-metal conductive layer 14 of the first non-metal current collector 10.

The anode layer 16 may be formed to a thickness of about 5 ~ 200 ㎛. The total thickness of the first non-metallic current collector 10 and the positive electrode layer 16 may be formed to a thickness of about 10 to 350 μm.

Conductive carbon such as graphite, carbon black, denka black, Lonza carbon, Super-P, MSC30, etc. may be used as a conductive agent suitable for forming the anode layer 16.

In addition, polymer binders suitable for forming the anode layer 16 include polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride and hexafluoro propylene, vinylidene fluoride and trifluoro. Copolymer of ethylene, copolymer of vinylidene fluoride and tetrafluoroethylene, polyethylene oxide, polypropylene oxide, polyvinyl chloride, polybutadiene, polystyrene, polyethylene, polypropylene, polymethyl acrylate, polyethyl acrylate, poly Methyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyacrylonitrile, cellulose, carboxymethyl cellulose, starch, polyacrylic acid, polyvinyl alcohol, polyvinylacetate, nylon, b Polymers such as pion or copolymers thereof, or Of which blends may be used.

In addition, a lithium active metal oxide, a conductive polymer, sulfur, or the like may be used as a cathode active material suitable for forming the cathode layer 16.

The negative electrode layer 26 may be formed by coating a slurry including a mixture of a conductive agent, a polymer binder, and a negative electrode active material on the second non-metal conductive layer 24 of the second non-metallic current collector 20.

The cathode layer 26 may be formed to a thickness of about 5 ~ 200 ㎛. The total thickness of the second nonmetallic current collector 20 and the negative electrode layer 26 may be formed to a thickness of about 10 to 350 μm.

Conductive carbon such as graphite, carbon black, denka black, lonza carbon, super-P, activated carbon MSC30, etc. may be used as a conductive agent suitable for forming the negative electrode layer 26.

In addition, polymer binders suitable for forming the negative electrode layer 26 may include polytetrafluoroethylene, polyvinylidene fluoride, copolymers of vinylidene fluoride and hexafluoropropylene, vinylidene fluoride and trifluoro. Copolymer of ethylene, copolymer of vinylidene fluoride and tetrafluoroethylene, polyethylene oxide, polypropylene oxide, polyvinyl chloride, polybutadiene, polystyrene, polyethylene, polypropylene, polymethyl acrylate, polyethyl acrylate, poly Methyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyacrylonitrile, cellulose, carboxymethyl cellulose, starch, polyacrylic acid, polyvinyl alcohol, polyvinylacetate, nylon, b Polymers such as pion or copolymers thereof, or Of which blends may be used.

In addition, suitable negative electrode active materials for constituting the negative electrode layer 26 may be MCMB (mesocarbon microbead), graphite, hard carbon and the like.

Alternatively, when the cathode layer 26 is to be formed of lithium metal, the cathode layer 26 is formed by depositing lithium metal or laminating a lithium metal film on the second nonmetal conductive layer 24 of the second nonmetal current collector 20. You may.

A polymer electrolyte layer 30 is formed between the anode layer 16 and the cathode layer 26 to bond them together and provide a path of movement of ions therebetween.

The polymer electrolyte layer 30 includes an organic electrolyte solution. The polymer electrolyte layer 30 is positioned between the positive electrode layer 16 and the negative electrode layer 26 to enhance the adhesion between the two electrodes, thereby integrating the film battery.

The polymer electrolyte layer 30 may be formed to a thickness of about 5 ~ 200 ㎛.

The polymer electrolyte layer 30 may include a polymer matrix, an inorganic additive, and an organic electrolyte solution.

Polymer matrix suitable for constituting the polymer electrolyte layer 30 is polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyl chloride, polystyrene, polyethylene oxide, polypropylene oxide, polybutadiene, cellulose, carboxymethyl cellulose , Nylon, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trifluoroethylene, vinylidene fluoride And copolymers of tetrafluoroethylene, polymethyl acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyvinylacetate, polyethylene oxide, poly Propylene oxide or Copolymers thereof, or blends thereof.

The inorganic additive suitable for constituting the polymer electrolyte layer 30 may be selected from silica, talc, alumina (Al ₂ O ₃ ), TiO ₂ , clay, zeolite, or a blend thereof. The inorganic additive in the polymer electrolyte layer 30 may be included in an amount of about 1 to 100% by weight based on the total weight of the polymer constituting the polymer matrix.

Organic electrolytes suitable for constituting the polymer electrolyte layer 30 are ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, methylpor Mate, ethylformate, gamma-butyrolactone or mixtures thereof. The organic electrolyte in the polymer electrolyte layer 30 may be included in an amount of about 1 to 500% by weight based on the total weight of the polymer constituting the polymer matrix.

The lithium salt in the electrolyte is lithium perchlorate (LiClO ₄ ), lithium triplate (LiCF ₃ SO ₃ ), lithium hexafluorophosphate (LiPF ₆ ), lithium iodide (LiI), lithium tetrafluoroborate (LiBF ₄ ), or at least one selected from the group consisting of lithium trifluoromethanesulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ). Lithium salt in the polymer electrolyte layer 30 may be included in an amount of about 1 to 100% by weight based on the total weight of the polymer constituting the polymer matrix.

2 is a flowchart illustrating a method of manufacturing a lithium secondary battery 100 according to an exemplary embodiment of the present invention. 1 and 2 will be described a method of manufacturing an exemplary lithium secondary battery 100 of the present invention.

First, in step 210, the first polymer film 12 and the second polymer film 22 are prepared, respectively.

In step 220, a first nonmetal conductive layer 14 is formed on the first polymer film 12, and a second nonmetal conductive layer 24 is formed on the second polymer film 22 to form a first nonmetal current collector. 10 and the second non-metallic current collector 20 are formed, respectively. As described with reference to FIG. 1, the first non-metal conductive layer 14 and the second non-metal conductive layer 24 may be formed on one side of the first polymer film 12 and the second polymer film 22, respectively. It can be formed by coating a tube paste, nanoparticle conductive carbon paste, nanoparticle metal paste, conductive polymer, or ITO paste.

In operation 230, a cathode active material slurry is coated on the first nonmetal conductive layer 14 of the first nonmetal current collector 10 to form a cathode layer 16. In addition, a cathode layer 26 is formed on the second nonmetal conductive layer 24 of the second nonmetal current collector 20. The negative electrode layer 26 may be formed by a method of coating a negative electrode active material slurry on the second non-metal conductive layer 24, a method of depositing lithium metal, or a method of laminating a lithium metal film.

The positive electrode active material slurry may be formed of a mixture of a conductive agent, a polymer binder, and a positive electrode active material, and exemplary specific materials thereof are as described with reference to FIG. 1.

The negative electrode active material slurry may be formed of a mixture of a conductive agent, a polymer binder, and a negative electrode active material, and exemplary specific materials thereof are as described with reference to FIG. 1.

In step 240, the structure as illustrated in FIG. 1 is completed by forming the polymer electrolyte layer 30 including the organic electrolyte between the anode layer 16 and the cathode layer 26. To this end, a method of coating or laminating a polymer film containing an organic electrolyte on the upper surface of each of the anode layer 16 and the cathode layer 26 may be used.

In step 250, the structure as shown in Figure 1 obtained through steps 210 to 240 is sealed in a conventional manner to complete the ultralight thin lithium secondary battery according to the present invention.

The lithium secondary battery 100 according to the exemplary embodiment of the present invention as described with reference to FIGS. 1 and 2 may provide an improved filling density and energy density per weight. In addition, by using a polymer electrolyte instead of a separator / liquid electrolyte system as in the prior art, it is possible to enhance stability in the cell, and to improve long life and durability. In addition, the lithium secondary battery 100 according to the present invention can implement ultra-thin and sealed single cells, simplify the manufacturing process during winding and lamination, and the manufacturing process is easy.

Hereinafter, a method of manufacturing a lithium secondary battery according to the present invention will be described in more detail with reference to specific manufacturing examples. However, the following preparation examples are illustrated to aid the understanding of the present invention, and the scope of the present invention should not be construed as being limited thereto, and various modifications and changes may be made from the following preparation examples without departing from the spirit of the present invention. It is possible.

Production Example  One

A 25 μm thick transparent polyethylene terephthalate film was laminated with a 50 μm thick opaque polyethylene terephthalate film to form a polyester film of a two-layer film. At this time, both surfaces of the two films were surface-treated by corona discharge before the lamination. A 6 μm thick conductive carbon paste was coated on one side of the bilayer film prepared as described above to prepare a nonmetal current collector for the positive electrode.

Production Example  2

A nonmetallic current collector for positive electrode was prepared in the same manner as in Production Example 1, except that a 3 μm thick conductive carbon paste was coated on one side of the bilayer film.

Production Example  3

Non-metallic collector for positive electrode in the same manner as in Preparation Example 1, except that a transparent polyethylene terephthalate film having a thickness of 2 μm and an opaque polyethylene terephthalate film having a thickness of 10 μm were used and a conductive carbon paste having a thickness of 3 μm was coated. The whole was prepared.

Production Example  4

A nonmetallic current collector for a positive electrode was manufactured in the same manner as in Preparation Example 1, except that a 1 μm-thick ITO paste was coated on the surface of the bilayer film.

Production Example  5

In the same manner as in Preparation Example 1, except that a transparent polyethylene terephthalate film having a thickness of 2 μm and an opaque polyethylene terephthalate film having a thickness of 10 μm were used, and a 1 μm thick ITO paste was coated on the surface of the bilayer film. A nonmetallic current collector for the positive electrode was prepared.

Production Example  6

A 25 μm thick transparent polyethylene terephthalate film was laminated with a 50 μm thick opaque polyethylene terephthalate film to form a polyester film of a two-layer film. At this time, the two films were surface-treated on both sides by corona discharge before each lamination. One side of the bilayer film prepared as described above was coated with a conductive carbon paste having a thickness of 6 μm, thereby finally preparing a nonmetallic current collector for the negative electrode.

Production Example  7

A nonmetallic current collector for a negative electrode was manufactured in the same manner as in Production Example 6, except that a 3 탆 thick conductive carbon paste was coated on one side of the bilayer film.

Production Example  8

Non-metallic collector for negative electrode in the same manner as in Preparation Example 6, except that a transparent polyethylene terephthalate film having a thickness of 2 μm and an opaque polyethylene terephthalate film having a thickness of 10 μm were used and a conductive carbon paste having a thickness of 3 μm was coated. The whole was prepared.

Production Example  9

A nonmetallic current collector for the negative electrode was prepared in the same manner as in Preparation Example 6, except that the ITO paste having a thickness of 1 μm was coated on the surface of the bilayer film.

Production Example  10

In the same manner as in Example 6, except that a transparent polyethylene terephthalate film having a thickness of 2 μm and an opaque polyethylene terephthalate film having a thickness of 10 μm were used, and a 1 μm thick ITO paste was coated on the surface of the bilayer film. A non-metallic current collector for the negative electrode was produced.

Production Example  11

The positive electrode active material slurry was coated to a thickness of 60 μm on the 15 μm thick nonmetallic current collector prepared by Preparation Example 3, and the surface of the nonmetal conductive layer of the 15 μm thick nonmetallic collector prepared by Preparation Example 8 The negative electrode active material slurry was coated to a thickness of 60 μm to prepare electrode films. At this time, 80 wt% of lithium-manganese-nickel oxide powder, 12 wt% of Super-P, and 8 wt% of polyvinylidene fluoride were used as the cathode active material slurry. As a negative electrode active material slurry, 85 wt% of MCMB carbon powder, 8 wt% of Super-P, and 7 wt% of polyvinylidene fluoride were mixed and used. The planar size of the anode was cut to an area of 2 cm x 2 cm. At this time, the size of the negative electrode and the electrolyte film was determined based on the area of the positive electrode. 150 wt% of an electrolyte solution containing 1 mol of lithium hexafluorophosphate dissolved in an organic solvent mixed with ethylene carbonate and dimethyl carbonate based on a copolymer of vinylidene fluoride and hexafluoropropylene was prepared between the prepared electrode films. A lithium secondary battery was manufactured by inserting a plasticized polymer electrolyte film having a thickness of 25 μm and putting the lamination into a pouch.

Production Example  12

A lithium secondary battery was manufactured in the same manner as in Preparation Example 11, except that lithium metal particles were deposited to have a thickness of 25 μm on the nonmetallic current collector for negative electrode having a thickness of 15 μm prepared by Preparation Example 8. .

Production Example  13

A lithium secondary battery was manufactured in the same manner as in Preparation Example 11, except that the separator / electrolyte was used as the electrolyte system.

Production Example  14

A negative electrode film was prepared by depositing lithium metal particles in a thickness of 25 μm on the nonmetallic current collector for the positive electrode prepared in Preparation Example 5 and the nonmetallic current collector for the negative electrode prepared in Preparation Example 10, A lithium secondary battery was manufactured by the same method as in Preparation Example 11, except that was prepared.

Comparative example

In order to compare the characteristics with the lithium secondary batteries obtained in Production Examples 11, 12, 13 and 14, a positive electrode active material slurry and a negative electrode active material slurry were each 60 μm on the surface of a 15 μm thick aluminum current collector and a 15 μm thick copper current collector, respectively. Electrode films were prepared by coating to a thickness of. At this time, the positive electrode active material slurry and the negative electrode active material slurry of the same composition as in the corresponding preparation examples were used. A 25 μm thick separator was placed between the prepared electrode films, followed by lamination to form a lithium ion battery unit cell.

Evaluation example  One

The lithium secondary batteries prepared in Preparation Examples 11, 12, 13 and 14 and each of the lithium ion battery cells prepared in Comparative Example were charged to 4.7 V at a current density of 2.5 mA (C / 2 rate) and then discharged to 3.0 V. Charge and discharge characteristics and cycle stability were measured.

3 is a graph showing charge and discharge characteristics of the lithium secondary battery unit cells of Preparation Examples 11, 12, 13, and 14 according to the present invention. Evaluation of the charge and discharge characteristics of FIG. 3 is necessary to determine the design capacity of the lithium secondary battery before evaluating the cycle characteristics. It can be seen that the lithium secondary batteries according to the present invention exhibit excellent discharge capacity characteristics as compared with the case of the comparative example.

Evaluation example  2

4 is a graph illustrating cycle stability of the lithium secondary battery unit cells of Preparation Examples 11, 12, 13, and 14 according to the present invention. In FIG. 4, it can be seen that the lithium secondary batteries according to the present invention exhibit excellent discharge capacity retention characteristics due to enhanced interfacial adhesion between electrodes / electrolytes.

Evaluation example  3

5 is a graph showing energy density values per weight and volume of the lithium secondary batteries of Preparation Examples 11, 12, 13, and 14 according to the present invention. For this evaluation, a lithium secondary battery was prepared by putting it in a pouch as a jelly roll type rather than a single cell type. In Figure 5, in the case of the preparation examples according to the invention it can be seen that it shows an excellent energy density value compared to the case of the comparative example.

The lithium secondary battery according to the present invention is formed using a polymer current collector prepared by depositing or laminating copper or aluminum in a thin film form on a thin polymer film. Therefore, the weight of the metal can be greatly reduced by minimizing the amount of metal used compared to the existing metal current collector. In addition, due to the characteristics of the polymer film, the bending characteristics are very excellent, and the folding phenomenon of the film can be eliminated. The lithium secondary battery according to the present invention can be easily applied to a wearable PC or the like since it is possible to implement a battery that can be rolled or bent like a roll. In addition, it is possible to exhibit excellent filling density characteristics by minimizing the radius and volume of the battery implementation by lamination and winding, and it is possible to obtain improved results in energy density per weight. According to the method of manufacturing a lithium secondary battery according to the present invention, the process conditions such as tension during continuous production is also significantly reduced compared to when using a conventional metal current collector, it is easy to mass the cells. In addition, the use of a polymer electrolyte in terms of stability, there is no fear of leakage compared to the conventional liquid electrolyte / membrane system, the use of metal components in the cell is minimized, significantly reducing the burning time during the cell ignition, and also the ignition temperature It can be controlled so as not to rise sharply above the combustion temperature of the polymer material. It is possible to flexibly cope with the stress, volume expansion, and internal pressure increase in the cell by the relaxation ability of the polymer film in the entire film area, and thus it is possible to alleviate the internal pressure rise and swelling phenomenon caused by the volume expansion during the charge / discharge process of the battery. . Therefore, the cycle stability can be improved and the weight of the material can be increased to increase the energy density per weight. In addition, it is possible to wind in a very small size can significantly reduce the radius and volume compared to the conventional cylindrical cells based on the same capacity.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes by those skilled in the art within the spirit and scope of the present invention. This is possible.

Claims (20)

A first nonmetal current collector composed of a first polymer film and a first nonmetal conductive layer, A first electrode layer formed on the first non-metal conductive layer, A second nonmetal current collector composed of a second polymer film and a second nonmetal conductive layer, A second electrode layer formed on the second nonmetal conductive layer; A polymer electrolyte layer formed between the first electrode layer and the second electrode layer and containing an organic electrolyte solution, The first nonmetallic conductive layer and the second nonmetallic conductive layer are lithium secondary batteries, characterized in that each consisting of a nanoparticle metal paste coating layer, a conductive polymer coating layer, or an ITO paste coating layer. The method of claim 1, Each of the first polymer film and the second polymer film is a polyester-based polymer, a polyolefin-based polymer, a cellulose-based polymer, nylon, polyimide, or a combination thereof. The method of claim 1, Each of the first polymer film and the second polymer film has a single layer or a multilayer structure made of a single kind of polymer material, or a lithium secondary battery comprising a multi-layer structure including at least two kinds of different polymer materials. delete The method of claim 1, The first nonmetallic conductive layer and the second nonmetallic conductive layer each have a thickness of 10 kPa to 50 μm. The method of claim 1, The first electrode layer is made of a mixture of the first conductive agent, the first polymer binder and the positive electrode active material, The second electrode layer is a lithium secondary battery comprising a mixture of a second conductive agent, a second polymer binder and a negative electrode active material. The method of claim 6, The lithium secondary battery, characterized in that the first conductive agent and the second conductive agent is made of one conductive carbon selected from the group consisting of graphite, carbon black, denka black, Lonza carbon, super-P, and activated carbon MSC30, respectively. The method of claim 6, The first polymer binder and the second polymer binder are polytetrafluoroethylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, and air of vinylidene fluoride and trifluoroethylene, respectively. Copolymer, copolymer of vinylidene fluoride and tetrafluoroethylene, polyethylene oxide, polypropylene oxide, polyvinyl chloride, polybutadiene, polystyrene, polyethylene, polypropylene, polymethyl acrylate, polyethyl acrylate, polymethyl methacrylate With latex, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyacrylonitrile, cellulose, carboxymethyl cellulose, starch, polyacrylic acid, polyvinyl alcohol, polyvinylacetate, nylon, and Nafion Any mound selected from the group consisting of Here, or a lithium secondary battery comprising a blend of these. The method of claim 6, The cathode active material is a lithium secondary battery, characterized in that consisting of a lithium transition metal oxide, a conductive polymer, or sulfur. The method of claim 6, The anode active material is a lithium secondary battery, characterized in that consisting of MCMB (mesocarbon microbead), graphite, or hard carbon. The method of claim 1, The first electrode layer is made of a mixture of the first conductive agent, the first polymer binder and the positive electrode active material, The second electrode layer is a lithium secondary battery, characterized in that made of lithium metal. The method of claim 1, The polymer electrolyte layer is a lithium secondary battery, characterized in that consisting of a polymer film containing an organic electrolyte solution containing a lithium salt. The method of claim 1, The polymer electrolyte layer is a lithium secondary battery comprising an organic electrolyte solution containing a polymer matrix, an inorganic additive, and a lithium salt. The method of claim 13, The polymer matrix is polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyl chloride, polystyrene, polyethylene oxide, polypropylene oxide, polybutadiene, cellulose, carboxymethylcellulose, nylon, polyacrylonitrile, polyvinylidene Fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trifluoroethylene, copolymer of vinylidene fluoride and tetrafluoroethylene, poly Any selected from the group consisting of methyl acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyvinylacetate, polyethylene oxide, and polypropylene oxide Single A lithium secondary battery comprising a polymer or a blend thereof. The method of claim 13, The inorganic additive is a lithium secondary battery, characterized in that made of at least one material selected from the group consisting of silica, talc, alumina (Al ₂ O ₃ ), TiO ₂ , clay (Clay), and zeolite. The method of claim 13, The organic electrolyte is ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, methyl formate, ethyl formate, and gamma-butyrolactone Lithium secondary battery comprising any one selected from the group consisting of, or a mixture thereof. The method of claim 13, The lithium salt may be lithium perchlorate (LiClO ₄ ), lithium triplate (LiCF ₃ SO ₃ ), lithium hexafluorophosphate (LiPF ₆ ), lithium iodide (LiI), lithium tetrafluoroborate (LiBF ₄ ), and Lithium trifluoromethanesulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ) Lithium secondary battery, characterized in that at least one selected from the group consisting of. Preparing a first polymer film and a second polymer film; Forming a first nonmetallic current collector by forming a first nonmetallic conductive layer formed of a nanoparticle metal paste coating layer, a conductive polymer coating layer, or an ITO paste coating layer on the first polymer film; Forming a second nonmetallic conductive layer formed of a nanoparticle metal paste coating layer, a conductive polymer coating layer, or an ITO paste coating layer on the second polymer film to form a second nonmetallic current collector; Forming a first electrode layer on the first nonmetal current collector; Forming a second electrode layer on the second nonmetal current collector; And forming a polymer electrolyte layer comprising an organic electrolyte between the first electrode layer and the second electrode layer. Preparing a first polymer film and a second polymer film; Forming a first nonmetallic current collector by coating a carbon nanotube paste, a nanoparticle conductive carbon paste, a nanoparticle metal paste, a conductive polymer, or an ITO paste on the first polymer film to form a first nonmetal conductive layer; Forming a second nonmetallic conductive layer on the second polymer film to form a second nonmetallic current collector; Forming a first electrode layer on the first nonmetal current collector; Forming a second electrode layer on the second nonmetal current collector; And forming a polymer electrolyte layer comprising an organic electrolyte between the first electrode layer and the second electrode layer. Preparing a first polymer film and a second polymer film; Forming a first nonmetallic current collector by forming a first nonmetallic conductive layer on the first polymer film; Forming a second nonmetallic current collector by coating a carbon nanotube paste, a nanoparticle conductive carbon paste, a nanoparticle metal paste, a conductive polymer, or an ITO paste on the second polymer film to form a second nonmetal conductive layer; Forming a first electrode layer on the first nonmetal current collector; Forming a second electrode layer on the second nonmetal current collector; And forming a polymer electrolyte layer comprising an organic electrolyte between the first electrode layer and the second electrode layer.

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