KR20120006730A - Process for preparing lithium polymer secondary batteries employing gel polymerelectrolyte - Google Patents

Abstract

PURPOSE: A producing method of a secondary battery using a polyelectrolyte is provided to prevent the performance degradation of the battery by the expansion of an electrode, and to easily insert the polyelectrolyte in a gel state into the electrode. CONSTITUTION: A producing method of a secondary battery using a polyelectrolyte comprises the following steps: forming positive and negative electrode active material layers(120,140) on first and second base substrates(110,130), respectively; drying and heat-compressing the positive and negative electrode active material layers; forming polyelectrolyte layers(150) on unit current collectors(P1,P2) including the positive and negative electrode active material layers; attaching the polyelectrolyte layers to obtain a secondary battery laminate; and processing the secondary battery laminate to obtain a secondary battery unit.

Description

Process for Preparing Lithium Polymer Secondary Batteries Employing Gel PolymerElectrolyte

The present invention relates to a manufacturing process of a film type secondary battery using a polymer electrolyte.

Devices that store energy in particular devices, especially batteries, are developing in the direction of high output, light weight, small size, and improved reliability with the development of various electric and electronic products.

In particular, the basic principle of energy storage devices, which are classified as chemical cells, is to use the flow of electrons involved in chemical reactions. That is, the electromotive force can be formed by using a redox reaction between two metals having different ionization tendencies and a flow of electrons moving between materials in the process. In this case, the oxidation-reduction reaction causes metals with a high ionization tendency to give electrons to metal ions having a low tendency to ionize and oxidize themselves. On the contrary, metal ions having a small tendency to ionize are reduced to metals. The movement of electrons accompanying this chemical reaction becomes the electromotive force of the battery.

Therefore, the basic configuration of the battery is composed of an electrolyte that helps the ion movement and the two materials having different ionization tendency as the electrode. When the redox reaction between the two materials is sufficient or the electrolyte is in a state where ion transport is not possible, no further reaction occurs and generation of electromotive force is stopped.

An example of a chemical cell as such an energy storage device will be described with reference to FIG. 1.

As shown in FIG. 1, in the conventional chemical cell 1, conductive layers 14 and 24 serving as current collectors are disposed on base substrates 12 and 22 formed of a polymer film or the like. Electrodes having different ionization tendencies, which are distinguished from the anode layer 16 and the cathode layer 24, are formed on one surface of the substrate. A polymer electrolyte layer 30 is provided between each of the anode layer 16 and the cathode layer 24 to provide a movement path of ions. In addition, although not shown, the edge of the chemical cell is sealed by heat fusion or adhesive. In addition, when the polymer electrolyte layer is used, a separator (not shown) may be used because of a concern caused by contact between electrodes in a sealing process for sealing.

Such characteristics, such as the capacity of a chemical cell as a conventional energy storage device, tend to depend largely on the characteristics of the material, composition, adhesiveness, etc., which form each layered structure.

Therefore, it is very difficult to change the stacked structure of the two electrodes, the current collector layer, and the electrolyte layer, which are basically formed, which increases the thickness of the overall battery, and in order to increase the electric capacity, the overall thickness is inevitably larger. It has led to a problem that is contrary to the recent development direction of electronic products.

In particular, when the secondary battery is manufactured, when the polymer electrolyte is applied, the wettability at the interface between the electrode and the electrolyte is low, so that wettability is secured through prolonged immersion, resulting in a delay in the manufacturing process. In addition, after the electrode is processed to a desired shape in the manufacturing process, a polymer electrolyte is formed on one electrode surface, and the other electrode surface is overlapped and pressed to produce a bar, resulting in a problem of poor contact resistance. In addition, due to stability problems due to exposure to the outside, a lot of problems occur in the manufacturing process of the film-type secondary battery.

The present invention has been made to solve the above problems, an object of the present invention is to prepare a secondary battery using a polymer electrolyte in a gel or solid state, to prevent performance degradation due to the expansion of the electrode, and to the inside of the electrode It facilitates the penetration of the electrolyte in the gel state to lower the contact resistance between the electrode and the electrolyte, maximizes the adhesiveness of the polymer electrolyte, and processes the integrated electrode and electrolyte lamination module into a desired shape in a single step to process the process. It is to provide a manufacturing method that maximizes the efficiency of the manufacturing process.

The present invention as a means for solving the above problems, one step of forming a polymer electrolyte layer on a unit current collector comprising a positive electrode or a negative electrode active material layer; Bonding the polymer electrolyte layer to form a secondary battery laminate; It is possible to provide a secondary battery manufacturing method using a polymer electrolyte comprising; three steps of forming a secondary battery unit by collectively processing the secondary battery laminate.

In particular, the first step, a1) forming a positive electrode and a negative electrode active material layer on the first and second base substrate, respectively; a2) heating and compressing the cathode and anode active material layers after drying; a3) forming a solid polymer electrolyte layer on the cathode and anode active material layers; As shown in FIG.

In addition, the step a1) may be configured to further perform the step of improving the adhesion between the base substrate, the positive electrode and the negative electrode active material by performing a plasma surface treatment or an acid treatment on the base substrate.

In addition, in the step a1), the base substrate may use a substrate having flexible characteristics by coating a conductive material on a metal thin film or a non-conductive plastic substrate.

In addition, the positive electrode active material formed on the first base substrate of step a1) uses a base material comprising a copolymer as a lithium metal oxide, a conductive agent and a binder, the negative electrode active material formed on the second base substrate, Copolymers may be used for graphite carbon, lithium, lithium alloys, conductive agents and binders.

In this case, the lithium metal oxide may include any one of Co, Ni, Mn, Fe, Cr, and Zn, and the conductive agent is carbon black, and the binder is copolymer of PVdF, CMC, or PVA. Can be used.

The first base material used in the manufacturing process is a current collector may be nickel, carbon, stainless steel, aluminum, and the second base material may be made of copper, nickel, stainless steel, aluminum, or an alloy of two or more thereof. have.

In addition, the polyelectrolyte of the first step in the manufacturing process is a gel-like solid polymer electrolyte, Polyethylene Oxide, Polyethylene Glycol, Poly Acrylonitrile, Polytetrafluoroethylene, Poly (vinylidene fluoride), Poly (vinylidene fluoride-co-hexafluoropropylene), Polymethylmethacrylate, Polyvinyl chloride, etc. One or a mixture of two or more kinds.

In addition, the polyelectrolyte of the first step may be used as an organic solvent used in a gel-type solid polymer electrolyte, mixed with one or two or more of Acetonitrile, Propylene Carbonate, Dimethyl Carbonate, Ethylene Carbonate, Ethyl Methyl Carbonate, Sulfolane, LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , or the like may be used as the lithium salt used in the gel solid polymer electrolyte.

In the manufacturing step according to the present invention, the second step may include: b1) improving wettability by vacuum heating the solid polymer electrolyte; b2) adhering and heat-pressing the solid polymer electrolyte surface; As shown in FIG.

In this case, after the step b2), it may further comprise a step b3) to rapidly solidify the solid polymer electrolyte.

In addition, the three steps of the manufacturing step according to the present invention, the secondary battery laminated body may be carried out by a process of cutting a batch using a punching tool (punching tool), the secondary battery unit to be manufactured after the first current The method may further include forming terminals on the current collector and the second current collector. Furthermore, the method may further include forming a protective case part on the outer surface of the secondary battery unit by using an epoxy resin.

According to the present invention, a secondary battery is manufactured using a polymer electrolyte in a gel or solid state to prevent performance degradation due to the expansion of the electrode, and facilitates penetration of the gel electrolyte into the electrode, thereby making contact between the electrode and the electrolyte. The resistance can be lowered, and the laminated module of the integrated electrode and electrolyte is processed into a desired shape by maximizing the adhesiveness of the polymer electrolyte to reduce the processing process to maximize the efficiency of the manufacturing process.

In particular, it improves adhesion characteristics and ionic conductivity by using solid electrolyte, and can reduce overall resistance value by reducing contact resistance between interfaces through heating and pressing process, and improves process time through rapid cooling process, batch punching process, and vacuum heating process. In addition, it is possible to secure flexibility by using a flexible substrate.

1 is a conceptual diagram showing the basic configuration of a conventional secondary battery.
2 is a flowchart illustrating a manufacturing process of a secondary battery according to the present invention.
3, 4a and 4b is a process chart showing a manufacturing process of the secondary battery according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation according to the present invention. In the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and duplicate description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Figure 2 shows a process flow diagram illustrating a manufacturing process according to the present invention. 3, 4a and 4b show a process diagram according to the present invention.

Referring to FIG. 2, first, a manufacturing process according to the present invention may be performed by forming a polymer electrolyte layer on a unit current collector including a cathode or an anode active material layer and adhering the polymer electrolyte layer to a unit current collector. And forming two steps of forming a secondary battery unit by collectively processing the unit current collector.

Detailed processes according to the manufacturing procedure shown in FIG. 2 will be described in detail with reference to FIGS. 3, 4A, and 4B.

2 and 3, in the manufacturing process of the secondary battery according to the present invention to form a polymer electrolyte layer on a unit current collector formed by separately manufacturing a positive electrode and a negative electrode, and then bonded to the batch processing The process proceeds.

First, in step S1, a cathode active material 120, which is a cathode material, is coated on a cathode current collector 110 (hereinafter referred to as a 'first base substrate'), and a cathode current collector 130 (hereinafter, The negative electrode active material 140, which is a negative electrode material, is coated on the 'second base substrate'. In this case, in order to secure the adhesive force between the first base substrate 110 and the second base substrate 130 and the positive electrode and the negative electrode active material, it is more preferable that the surface treatment such as plasma treatment or acid treatment is performed. The first base 110 and the second base 130 may be a base material having a flexible (flexible) characteristics by coating a conductive material on a metal thin film or non-conductive plastic substrate. The nonconductive plastic substrate may be formed of, for example, a polyester polymer, a polyolefin polymer, a cellulose polymer, nylon, or polyimide, or a combination thereof. In addition, a single layer or a multilayer structure may be used in a single or a combination of two or more of the above. In particular, when the metal thin film or the conductive material is used as the first base, the metal and the conductive material may use any one of nickel, carbon, stainless steel, aluminum, or an alloy of two or more thereof as the current collector. In addition, the metal thin film or conductive material constituting the second base substrate may use copper, nickel, stainless steel, aluminum, or an alloy of two or more thereof.

In addition, after coating the positive and negative electrode active material layer, and drying and hot pressing (hot pressing) to form a unit current collector (P1, P2). The positive electrode active material formed on the first base substrate is a substrate including a lithium metal oxide, a conductive agent and a copolymer as a binder. The negative electrode active material formed on the second base substrate is graphite carbon, lithium, or lithium. Copolymers may be used as the alloy, the conductive agent and the binder. In this case, the lithium metal oxide may include any one of Co, Ni, Mn, Fe, Cr, and Zn, and the conductive agent is carbon black and the binder is copolymerized using PVdF, CMC, or PVA. Can be configured.

Thereafter, as a step S 2, a polymer electrolyte is coated on the surfaces of the unit current collectors P1 and P2 to form the polymer electrolyte layer 150. In this case, the polyelectrolyte is a gel-type solid polymer electrolyte, and includes one or more of Polyethylene Oxide, Polyethylene Glycol, Poly Acrylonitrile, Polytetrafluoroethylene, Poly (vinylidene fluoride), Poly (vinylidene fluoride-co-hexafluoropropylene), Polymethylmethacrylate, Polyvinyl chloride, etc. The substance mixed with 2 or more types can be used.

In particular, when forming the polymer electrolyte may include an organic solvent and a lithium salt, in this case, as the organic solvent used in the gel-type solid polymer electrolyte, Acetonitrile, Propylene Carbonate, Dimethyl Carbonate, Ethylene Carbonate, Ethyl Methyl Carbonate, The organic solvent formed by mixing 1 type (s) or 2 or more types of Sulfolane etc. can be used. In the case of lithium salts, at least one of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , and the like may be used as the lithium salt used in the gel solid polymer electrolyte.

Thereafter, in step S 3, the unit current collector layers P1 and P2 having the polymer electrolyte layers formed thereon are joined to form a secondary battery laminate.

In particular, in the bonding process, the unit current collector layers P1 and P2 are brought into contact with the polymer electrolyte layer to form a secondary battery laminate X. This process is heat-compressed by using a solid electrolyte having good adhesion properties and excellent ion conductivity, so that the contact resistance between interfaces can be reduced, thereby reducing the overall resistance value and making the thickness thinner. In particular, in this bonding process, by introducing a vacuum heating and heat fusion process, there is an advantage that can improve the wettability through vacuum heating. After bonding, a rapid cooling process may be introduced to solidify the gel polymer electrolyte layer, thereby significantly shortening the process time.

4A and 4B illustrate a processing step of processing the secondary battery unit after the formation of the secondary battery laminate X described above.

The secondary battery laminate (X) processed in step S 3 is punched using a punching equipment (T) in step S 41, which is very simple to realize a secondary battery having a desired shape in one step. It is formed by the process.

For example, after implementing the coin-type secondary battery unit (C) as in step S42, the terminal 160 is formed in step S43. The terminal 160 may be implemented by welding a terminal made of SUS to the positive electrode current collector (first base substrate) and the negative electrode current collector (second base substrate), and then, in step S44. A protective case unit 170 may be formed to block the secondary battery unit exposed to the outside from the outside by using an epoxy resin.

Of course, unlike the above-described process, the protective case portion 170 to weld the terminal to the secondary battery laminated body (X) itself without any additional processing, and then to block the external battery unit exposed to the outside using epoxy resin. Of course, it can be implemented as a process of forming (S 51 ~ S 53 steps).

Hereinafter, the present manufacturing process will be described once again through a manufacturing example as an embodiment of the above-described manufacturing process.

{Production example}

1) LiCoO ₂ as the positive electrode active material, carbon black as the conductive agent and PVdF (Poly Vinylidenefluoride) as the binder were well dispersed by agitation to obtain a slurry, which was coated / dried on an aluminum current collector and hot pressed.

2) Graphite as a negative electrode active material, carbon black as a conductive agent, and PVdF (Poly Vinylidenefluoride) as a binder were well dispersed by agitation to obtain a slurry, which was coated / dried on a copper current collector and hot pressed.

3) PAN (Polyacrylonitrile) was added to 1M LiPF6 in EC / EMC as a solid polymer electrolyte, and the mixture was heated to 120 ° C. and mixed.

4) The polymer electrolyte prepared on the cathode / cathode was coated and coated, followed by vacuum heating. (3min./120℃)

5) 1ton, 90 ° C, 1min. Hot pressing is carried out.

6) After cooling at -10 ℃ for 1min, punch the integrated anode / electrolyte / cathode at once in the form of coin.

7) SUS terminals were formed on the positive electrode current collector and the negative electrode current collector.

8) The cell was manufactured by blocking the surface exposed to the outside with epoxy resin.

The manufacturing process for implementing the above production example can lower the viscosity of the electrolyte in the gel (Gel) to facilitate the penetration of the electrolyte between the electrode pores to lower the contact resistance between the electrode / electrolyte, in particular through a solid electrolyte with adhesion Since both the positive electrode, the electrolyte and the negative electrode are integrated to process the cutting and the like at one time, the convenience of the process is realized, and there is basically a safety benefit because there is no concern about liquid leakage. In addition, it is possible to manufacture a flexible film-type lithium secondary battery using a flexible substrate and a solid polymer electrolyte in a gel form.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

110: first base material
120: positive electrode active material
130: second base
140: negative electrode active material
150: polymer electrolyte layer
160: terminal
170: protective case
C: coin type secondary battery unit
P1, P2: unit current collector
X: secondary battery laminate

Claims (15)

Forming a polymer electrolyte layer on a unit current collector including a positive electrode or a negative electrode active material layer;
Bonding the polymer electrolyte layer to form a secondary battery laminate;
Three steps of collectively processing the secondary battery laminate to form a secondary battery unit;
Secondary battery manufacturing method using a polymer electrolyte comprising a.
The method according to claim 1,
The first step,
a1) forming a positive electrode and a negative electrode active material layer on the first and second base substrates, respectively;
a2) heating and compressing the cathode and anode active material layers after drying;
a3) forming a solid polymer electrolyte layer on the cathode and anode active material layers;
Secondary battery manufacturing method using a polymer electrolyte comprising a.
The method according to claim 2,
Step a1),
A method of manufacturing a secondary battery using a polymer electrolyte in which a step of improving adhesion between the base substrate, the positive electrode, and the negative electrode active material is performed by performing a plasma surface treatment or an acid treatment on the base substrate.
The method according to claim 3,
Step a1),
The base substrate is a secondary battery manufacturing method using a polymer electrolyte which is a substrate having a flexible (flexible) characteristics by coating a conductive material on a metal thin film or non-conductive plastic substrate.
The method according to claim 2,
Step a1),
The positive electrode active material formed on the first base substrate, using a base material comprising a copolymer as a lithium metal oxide, a conductive agent and a binder,
The negative electrode active material formed on the second base substrate is a secondary battery manufacturing method using a graphite-based carbon, lithium, lithium alloy, a polymer electrolyte using a copolymer as a conductive agent and a binder.
The method according to claim 5,
The lithium metal oxide may include any one of Co, Ni, Mn, Fe, Cr, and Zn, and the conductive agent is carbon black, and the binder is a polymer electrolyte using any one of PVdF, CMC, and PVA. Secondary battery manufacturing method using.
The method according to claim 5,
The first base material is a current collector, nickel, carbon, stainless steel, aluminum, the second base material is a secondary battery manufacturing method using a polymer electrolyte made of copper, nickel, stainless steel, aluminum or two or more of these alloys.
The method according to claim 1,
The polymer electrolyte of the first step,
As a gel solid polymer electrolyte, polyethylene oxide, polyethylene glycol, poly acrylonitrile, polytetrafluoroethylene, poly (vinylidene fluoride), poly (vinylidene fluoride-co-hexafluoropropylene), polymethylmethacrylate, polyvinyl chloride, etc. Secondary battery manufacturing method using a polymer electrolyte comprising.
The method according to claim 8,
The polymer electrolyte of the first step,
An organic solvent used in a gel-type solid polymer electrolyte, a method of manufacturing a secondary battery using a polymer electrolyte in which one or two or more of Acetonitrile, Propylene Carbonate, Dimethyl Carbonate, Ethylene Carbonate, Ethyl Methyl Carbonate, and Sulfolane are used.
The method according to claim 9,
The polymer electrolyte of the first step,
A method for manufacturing a secondary battery using a polymer electrolyte using at least one of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , and the like as a lithium salt used in a gel solid polymer electrolyte.
The method according to claim 1,
In the second step,
b1) vacuum-heating the solid polymer electrolyte to improve wettability;
b2) adhering and heat-pressing the solid polymer electrolyte surface;
Secondary battery manufacturing method using a polymer electrolyte comprising a.
The method of claim 11,
After step b2),
A secondary battery manufacturing method using a polymer electrolyte further comprising the step b3) of solidifying the solid polymer electrolyte by rapid cooling.
The method according to claim 1 or 11,
The third step,
A method of manufacturing a secondary battery using a polymer electrolyte, which is performed by a process of collectively cutting the secondary battery laminate using a punching tool.
The method according to claim 13,
The secondary battery unit manufactured by the batch cutting process further comprises the step of forming a terminal on the first current collector and the second current collector secondary battery manufacturing method using a polymer electrolyte.
The method according to claim 14,
The secondary battery manufacturing method using a polymer electrolyte further comprising the step of forming a protective case portion on the outer surface of the secondary battery unit using an epoxy resin.

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