KR100462781B1 - Lithium battery without anode active material and process for preparing the same - Google Patents

Abstract

The present invention relates to a lithium battery that does not include a negative electrode active material and a method for manufacturing the same, and more specifically, to produce a metal lithium having the highest energy density per weight without using a negative electrode active material to improve the energy density and manufacturing cost The present invention relates to a lithium battery having improved economics and a method of manufacturing the same.

Description

Lithium battery without anode active material and manufacturing method thereof {Lithium battery without anode active material and process for preparing the same}

The present invention relates to a lithium battery that does not include a negative electrode active material and a method for manufacturing the same, and more specifically, to produce a metal lithium having the highest energy density per weight without using a negative electrode active material to improve the energy density and manufacturing cost The present invention relates to a lithium battery having improved economics and a method of manufacturing the same.

In general, rechargeable batteries capable of charging and discharging are being actively researched by the development of portable electronic devices such as cellular phones, notebook computers, and computer cam codes. In particular, such a secondary battery is a variety of types such as nickel-cadmium battery, lead acid battery, nickel hydrogen battery, lithium ion battery, lithium polymer battery, metal lithium secondary battery, air zinc storage battery. Among the batteries, the lithium secondary battery has an operating voltage of 3.6 V, which is about three times longer than a nickel-cadmium battery or nickel-hydrogen battery, which is widely used as a power source for electronic devices, and has an excellent energy density per unit weight. The demand is growing rapidly.

The lithium secondary battery may be classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. Generally, a battery using a liquid electrolyte is a lithium ion battery and a battery using a polymer electrolyte is called a lithium polymer battery.

In general, in manufacturing a lithium secondary battery, first, a material in which an active material, a binder, and a plasticizer are mixed is applied to a positive electrode current collector and a negative electrode current collector to prepare a positive electrode plate and a negative electrode plate, and laminated on both sides of a separator to form a battery having a predetermined shape. A cell is formed, the battery cell is inserted into a battery case, and an electrolyte solution is injected to complete a battery pack.

Lithium secondary batteries are generally finished into products after completion of battery manufacturing and chemical conversion and aging processes. The chemical conversion process is to activate the battery by repeating charging and discharging after battery assembly. In this process, lithium ions from the lithium metal oxide used as the cathode active material during charging are moved to and inserted into the carbon electrode used as the cathode active material.

Lithium secondary batteries can be divided into two types according to the method. That is, a battery composed of a positive electrode material having a structure capable of accepting lithium ions, using a material having an initial lithium supply source at the negative electrode, for example, a lithium metal or a lithium compound, and a lithium supply source at the positive electrode. It is divided into batteries that use materials and consist of materials that can store lithium ions on the negative electrode. The latter battery is called a lithium ion secondary battery.

The former lithium battery operates as a battery immediately after assembling the battery, thus eliminating the need for a battery activation process called a chemical conversion process and having a high energy density. However, the lithium battery is dangerous because it directly deals with highly reactive negative electrode materials. Not only is it difficult to use, but also has many problems such as lifespan and safety.

The latter battery is widely used because it uses a safe positive / cathode material and has excellent safety and performance. However, due to the limited capacity of the negative electrode active material, there is a problem that it is lower than the cell of the electron in terms of energy density.

Accordingly, there is still a need for a lithium battery having only the former and the latter advantages, having a high energy density and excellent performance such as a lifetime.

The technical problem to be achieved by the present invention is to provide a method for manufacturing a lithium battery using a positive electrode active material and the negative electrode is composed of a current collector only without a negative electrode active material.

Another object of the present invention is to provide a lithium battery obtained by employing the above manufacturing method.

The present invention to achieve the above technical problem,

Preparing a positive electrode plate by applying a positive electrode coating material including an active material and a binder to a positive electrode current collector;

A process for preparing a negative electrode plate by applying a negative electrode coating material including a binder to a negative electrode current collector, wherein the binder is vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl meta Comprising acrylate, polytetrafluoroethylene and mixtures thereof;

Stacking the positive electrode plate and the negative electrode plate to form a battery cell; And

Storing the battery cell in a battery case and injecting a composition for forming a polymer electrolyte;

It provides a method for producing a lithium battery comprising a.

In the above production method, a separator made of an insulating resin may be further interposed between the positive electrode plate and the negative electrode plate.

In the manufacturing method, the shape of the lithium battery is preferably laminated.

In the above method, it is preferable to further apply a conductive material having a thickness of 5 μm or less to the negative electrode current collector.

In the manufacturing method, the material for applying the positive electrode may further include a plasticizer.

In the manufacturing method, the material for applying the positive electrode may further include a conductive agent.

In the manufacturing method, the material for applying the negative electrode may further include a plasticizer.

In the manufacturing method, the negative electrode coating material may further include a conductive agent.

The plasticizer is preferably dibutyl phthalate.

The conductive agent is preferably carbon black.

After the injection of the composition for forming a polymer electrolyte in the manufacturing method may be further performed heat treatment or ultraviolet irradiation treatment.

The composition for forming a polymer electrolyte in the production method is characterized in that it comprises a polymer resin, a polymerization initiator and an electrolyte solution.

The polymerization initiator is preferably a peroxide having 6 to 40 carbon atoms.

The electrolyte may include an organic solvent and a lithium salt.

The present invention provides a lithium battery manufactured by the above manufacturing method in order to achieve another technical problem of the present invention.

In general, a lithium battery is coated with an electrode active material, a solvent, a binder, a plasticizer, and, optionally, a conductive material, on an electrode current collector to prepare an electrode plate. A separator is inserted between the negative electrode plate and the positive electrode plate thus manufactured to form a battery cell having a predetermined shape. The battery cell is stored in a case, and then the electrolyte is injected and sealed to complete the battery pack.

In the lithium battery of the present invention, a battery in which a negative electrode plate (a current collector or a pretreated current collector) without a negative electrode active material and a positive electrode plate of a conventional lithium battery is physically pasted with a separator therebetween, in particular, a positive / negative electrode It is characterized by a stacked battery.

The lithium battery of the present invention does not directly handle a highly reactive lithium metal when manufacturing the battery, the safety is improved, the lithium battery using a conventional negative electrode active material to solve the problem that the energy density is reduced due to the limited capacity of the negative electrode active material, etc. It becomes possible.

That is, unlike the conventional lithium ion battery in which lithium ions having energy are stored in the negative electrode active material, the lithium battery of the present invention stores energy by uniformly generating lithium metal in the negative electrode current collector without using the negative electrode active material. Is using the way.

In the case where the anode / cathode is configured in parallel as in the lithium battery of the present invention, a uniform lithium metal is formed on the cathode electrode plate in the chemical conversion process after battery assembly, which acts as an essential element for maintaining performance such as life.

One of the problems of the conventional lithium metal has been a problem of safety due to dendrite formation, but the lithium battery of the present invention can be applied to an electrolyte system having a high surface tension as one of methods for suppressing dendritic formation. In particular, a solid polymer electrolyte or a gel polymer electrolyte system can be applied.

Therefore, the lithium battery of the present invention can produce a battery having excellent safety by forming densely formed lithium metal without forming a dendritic metal, and on the other hand, it generates high energy density by using metal lithium having the highest energy density per weight without using a negative electrode active material. It is possible to manufacture a battery having a density, and also there is no need to use a negative electrode active material, thereby reducing the cost and shortening the process.

In the negative electrode plate used in the lithium battery of the present invention, since the positive electrode / negative electrode is physically or mechanically coupled with the separator interposed therebetween, a conductive material having a thickness of 5 μm or more can be applied to the negative electrode current collector. In order to improve the binding power of the binder can be applied.

The composition for forming a polymer electrolyte according to the present invention includes a polymer resin, a polymerization initiator, and an electrolyte solution, and the polymer resin is not particularly limited, and any material used as a binder of an electrode plate may be used. Examples thereof include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate and mixtures thereof. The polymerization initiator is preferably an organic peroxide having 6 to 40 carbon atoms, and the electrolyte solution comprises a lithium salt and an organic solvent.

Subsequently, the composition for forming a polymer electrolyte is impregnated or coated on an electrode. In some cases, the resultant is subjected to a polymerization reaction by heat treatment or UV irradiation. Here, the heat treatment temperature is different depending on the half-life of the initiator of the radical reaction used, but 40 to 110 ℃ is suitable but more preferably 60 to 85 ℃. If the temperature of the thermal polymerization is too low, a large amount of unreacted monomer remains or the reaction time becomes long, resulting in the cost of the manufacturing process. In addition, when the reaction temperature is too high, there is a problem that the amount of decomposition of the lithium salt significantly increases.

In the polymer electrolyte formation composition, the content of the polymerization initiator is preferably 0.3 to 5 parts by weight based on 100 parts by weight of the polymer resin. If the content of the polymerization initiator is less than 0.3 parts by weight, the polymerization reactivity is lowered. If the content of the polymerization initiator is more than 5 parts by weight, the molecular weight of the polymer cannot be largely grown, resulting in poor mechanical properties as the polymer electrolyte.

The mixed weight ratio of the polymer resin and the electrolyte in the polymer electrolyte is 1: 2 to 1:35. If the content of the polymer with respect to the electrolyte exceeds the above range, the conductivity of the ions of the polymer electrolyte is lowered, if it is less than the above range is not preferable because the gel is not formed.

In addition, the electrolyte constituting the composition for forming a polymer electrolyte of the present invention is composed of a lithium salt and an organic solvent, wherein the organic solvent is propylene carbonate, ethylene carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butylolactone, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamido, dimethyl sulfoxide, dioxy acid, 1, 2-dimethoxyethane , Sulfolane, dichloroethane, chlorobenzene, nitrobenzene, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl butyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, Non-aqueous solvents, such as diethylene glycol and dimethyl ether, or the mixed solvent which mixed 2 or more types in these solvents To when and, in particular, propylene carbonate, ethylene carbonate, butylene is any of the preferable be contained, and at the same time to be included in the dimethyl carbonate, which is one of the methyl ethyl carbonate, diethyl carbonate of the carbonate. And it is preferable that the density | concentration of the electrolyte solution which consists of a lithium salt and an organic solvent is 0.6-1.5M.

In the present invention, the organic solvent may further include a fluorinated aromatic hydrocarbon compound. When the fluorinated aromatic hydrocarbon compound is further included, there is an advantage that the low temperature property is improved. The content of this fluorinated aromatic hydrocarbon compound is preferably a mixing weight ratio of ethylene carbonate and fluorinated aromatic hydrocarbon compound of 99: 1 to 70:30. In this case, the fluorinated aromatic hydrocarbon compound is one selected from the group consisting of 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2-fluorobenzene, 3-fluorobenzene, and 4-fluorobenzene That's it. When the fluorinated aromatic hydrocarbon compound exceeds the above range, the solubility of the lithium salt is lowered, and when the fluorinated aromatic hydrocarbon compound is below the above range, the low temperature improvement effect is insignificant, which is not preferable.

Looking at the method for producing a lithium battery of the present invention using the above-described polymer electrolyte is as follows.

The lithium battery of the present invention can be produced according to the following method of the polymer electrolyte.

First, the polymer resin, a polymerization initiator, and an electrolyte are mixed to obtain a composition for forming a polymer electrolyte.

Separately, a positive electrode plate is manufactured according to a conventional method used in manufacturing a lithium battery. Such a positive electrode plate includes an active material and a binder dissolved in a solvent, and is obtained by casting and drying an anode coating material on aluminum foil, which may further include a plasticizer or a conductive agent. In this case, a lithium metal composite oxide, a transition metal compound, a sulfur compound, or the like is used as the cathode active material.

In addition, a negative electrode plate according to the present invention may be prepared, and the negative electrode plate may include a binder, and may be obtained by casting and drying a negative electrode coating material which may further include a plasticizer or a conductive agent in a copper foil and dried, in which case the negative electrode active material is Do not use.

Then, when necessary, a separator made of an insulating resin having a network structure is inserted between the positive electrode plate and the negative electrode plate, and stacked to form an electrode structure, and then put into a battery case to assemble a battery.

Then, the lithium battery of the present invention is completed by injecting the composition for forming the polymer electrolyte into the battery case in which the electrode structure is stored, and then performing an in-polymerization reaction by selectively heat treatment or ultraviolet irradiation.

Specific examples of the separator made of the insulating resin include polyethylene separator, polypropylene separator, polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator or polypropylene / polyethylene Use a polypropylene three-layer separator.

In the above production method, the heat treatment temperature is carried out at 40 to 110 ℃, especially 60 to 85 ℃ to form a gel polymer electrolyte. It is preferable that the thickness of the polymer electrolyte is 5 to 90 μm, and in this range, it is excellent in characteristics such as ionic conductivity of the polymer electrolyte.

The lithium battery of the present invention prepared according to the method described above may be both a lithium primary battery and a lithium secondary battery.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

<Example 1>

1 g of polyvinylidene fluoride and 10 mg of lauryl peroxide were added to 30 g of a mixed solvent of 1.3 mol / L of LiPF ₆ in which EC and DEC were dissolved (weight ratio is 3: 7), thereby obtaining a composition for forming a polymer electrolyte.

A slurry was prepared by mixing 3 g of polyvinylidene fluoride, 94 parts by weight of C-10 (Japan Chemical Co., Ltd.), and 3 parts by weight of superpey to 50 g of N-methylpyrrolidone (NMP). The cathode was prepared by coating to a μm thickness.

An anode was prepared by dissolving 9 g of mesocarbon fiber (Petoca Co., Ltd.) in 10 ml of N-methylpyrrolidone and coating it on a copper substrate to a thickness of 170 μm.

A polyethylene separator was inserted between the cathode and the anode and stacked and stored in the battery case. Subsequently, a suitable amount of the above-described composition for forming a polymer electrolyte was injected into the battery case, and the resultant was heated at a temperature of about 70 ° C. for about 2 hours to perform thermal polymerization in the battery to complete a lithium secondary battery.

Comparative Example 1

1 g of polyvinylidene fluoride and 10 mg of lauryl peroxide were added to 30 g of a mixed solvent of 1.3 mol / L of LiPF ₆ in which EC and DEC were dissolved (weight ratio is 3: 7), thereby obtaining a composition for forming a polymer electrolyte.

A slurry was prepared by mixing 3 g of polyvinylidene fluoride, 94 parts by weight of C-10 (Japan Chemical Co., Ltd.), and 3 parts by weight of superpey to 50 g of N-methylpyrrolidone (NMP). The cathode was prepared by coating to a μm thickness.

An anode was prepared by dissolving 9 g of mesocarbon fiber (Petoca) and 1 g of polyvinylidene fluoride in 10 ml of N-methylpyrrolidone, which was coated on a copper substrate to a thickness of 170 μm.

A polyethylene separator was inserted between the cathode and the anode and stacked and stored in the battery case. Subsequently, an appropriate amount of the above-described composition for forming a polymer electrolyte was injected into the battery case, and the resultant was heated at a temperature of about 70 ° C. for about 2 hours to perform thermal polymerization in the battery to complete a lithium secondary battery.

In the lithium secondary battery prepared according to Example 1 and Comparative Example 1, in the case of Example 1 not using the negative electrode active material proposed in the present invention the energy density per weight is improved and the economical efficiency in terms of manufacturing cost It is possible to provide a lithium battery.

Claims (16)

Preparing a positive electrode plate by applying a positive electrode coating material including an active material and a binder to a positive electrode current collector; The negative electrode coating material comprising a binder is applied to a negative electrode current collector to prepare a negative electrode plate, wherein the binder is vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl Methacrylate, polytetrafluoroethylene or mixtures thereof; Stacking the positive electrode plate and the negative electrode plate to form a battery cell; And Storing the battery cell in a battery case and injecting a composition for forming a polymer electrolyte; Method for producing a lithium battery comprising a. The method of manufacturing a lithium battery according to claim 1, further comprising a separator made of an insulating resin interposed between the positive electrode plate and the negative electrode plate. The manufacturing method according to claim 1, wherein the lithium battery has a laminated shape. The method of claim 1, wherein a conductive material having a thickness of 5 μm or less is further applied to the negative electrode current collector. The method of claim 1, wherein the cathode coating material further comprises a plasticizer. The method of claim 1, wherein the anode coating material further comprises a conductive agent. The method of claim 1, wherein the negative electrode coating material further comprises a plasticizer. The method of claim 1, wherein the negative electrode coating material further comprises a conductive agent. The production method according to claim 5 or 7, wherein the plasticizer is dibutyl phthalate. The manufacturing method according to claim 6 or 8, wherein the conductive agent is carbon black. The method according to claim 1, further comprising heat treatment or ultraviolet irradiation after the injection of the composition for forming the polymer electrolyte. delete The method of claim 1, wherein the composition for forming a polymer electrolyte comprises a polymer resin, a polymerization initiator, and an electrolyte solution. The method of claim 13, wherein the polymerization initiator is a peroxide having 6 to 40 carbon atoms. The production method according to claim 13, wherein the electrolyte solution contains an organic solvent and a lithium salt. A lithium battery produced by the method of any one of claims 1 to 15.