KR100467695B1 - Electrolyte matrix composition comprising activator for polymerizing monomer based on acrylate having multifunctionality and lithium battery employing the same - Google Patents

Abstract

The present invention relates to a composition for forming an electrolyte matrix comprising an acrylate-based monomer polymerization initiator having a multifunctional group, and a lithium battery employing the same, specifically, by controlling the rate of the start reaction at the thermal polymerization temperature of the lithium battery The present invention relates to a composition for forming an electrolyte matrix capable of improving electrochemical and physical properties, and a lithium battery employing the same.

Description

Electrolytic matrix composition comprising activator for polymerizing monomer based on acrylate having multifunctionality and lithium battery employing the same}

The present invention relates to a composition for forming an electrolyte matrix comprising an acrylate-based monomer polymerization initiator having a multifunctional group, and a lithium battery employing the same, specifically, by controlling the rate of the start reaction at the thermal polymerization temperature of the lithium battery The present invention relates to a composition for forming an electrolyte matrix capable of improving electrochemical and physical properties, and a lithium battery employing 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 the battery case, and the electrolyte is injected to complete the battery pack.

In particular, in a polymer battery in which a liquid electrolyte solution, an acrylate monomer and an initiator are mixed and polymerized in a battery to form a gel polymer electrolyte, the electrochemical and physical properties of the polymer layer formed after polymerization have a direct or indirect effect on battery characteristics. Element.

On the other hand, in the polymer battery, it is considered that the characteristics of the polymer layer can be changed by controlling the polymerization process. The important factors in the polymerization process are liquid electrolyte composition, type of monomer, functional group of monomer, content ratio of liquid electrolyte and monomer, and initiator type. , Initiator content and reaction temperature. In particular, among such elements, conventionally, as a monomer, an acrylate monomer of a highly reactive polyfunctional group has been used, and a low temperature initiator having a low start temperature has been used as an initiator.

In this case, however, initiation reaction and other side reactions may occur at room temperature due to the initiator in the process of injecting the mixed solution into the cell and then leaving it at room temperature before polymerization. The increase in viscosity of the pre-gel solution due to such a slight initiation reaction makes it difficult to impregnate the pre-gel solution into the cathode electrode during the room temperature standing process, and there is a concern that the surface of the electrode may be deteriorated by the side reaction. In addition, the polymer structure formed during the thermal polymerization process has a problem that it is difficult to have a three-dimensional network structure due to the rapid start reaction.

The technical problem to be achieved by the present invention is to provide a composition for forming a polymer electrolyte capable of controlling the polymerization rate in the room temperature leaving process before the polymerization step.

Another object of the present invention is to provide a lithium battery employing the composition.

Another object of the present invention is to provide a method of manufacturing the lithium battery.

The present invention to achieve the above technical problem,

It provides a composition for forming a polymer electrolyte comprising a liquid electrolyte, a polyfunctional acrylate monomer and a polymerization initiator having a half-life (10 hours) of 90 to 110 ° C.

It is preferable that the polymerization initiator used for the said composition is a peroxide type initiator.

The polymerization initiator used in the composition is t-butyl peroxy 3,5,5-trimethyl hexanoate, t-amyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy acetate, t-butyl Peroxy benzoate, 1,1-di-t-butyl peroxy-3,5,5-trimethylcyclo hexane, 1,1-di-t-butyl peroxy cyclohexane, 2,2-di- (t- At least one selected from the group consisting of butyl peroxy) butane and 2,2-bis (4,4-di-t-butyl peroxy cyclohexyl) propane is preferred.

The polyfunctional acrylate monomer used in the composition is not particularly limited, but at least one selected from the group consisting of alkyl acrylate esters, urethane acrylate based acrylamides, styrene, N-vinyl amides, and alkyl vinyl ethers. It is preferable to be one.

It is preferable that the polyfunctional acrylate-type monomer used for the said composition is 1-10 weight part with respect to 100 weight part of said liquid electrolyte solutions.

It is preferable that the polymerization initiator used for the said composition is 0.1-20 weight part with respect to 100 weight part of said polyfunctional acrylate monomers.

The liquid electrolyte used in the composition is characterized in that it comprises an organic solvent and a lithium salt.

Lithium salt constituting the liquid electrolyte is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, at least one selected from the group consisting of LiPF ₆ , LiBF ₄ preferably.

The organic solvent constituting the liquid electrolyte is ethylene carbonate (EC), diethyl carbonate (DEC), γ-butyrolactone (GBL), propylene carbonate (PC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC) and At least one selected from the group consisting of diethyl carbonate (DEC) and vinylene carbonate (VC), and in some cases 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2-fluorobenzene, It may further comprise at least one fluorinated aromatic hydrocarbon compound selected from the group consisting of 3-fluorobenzene and 4-fluorobenzene.

In order to achieve the above technical problem of the present invention,

Cathode;

Anode; And

Provided is a lithium battery interposed between the cathode and the anode and comprising a polymer electrolyte obtained by the composition for forming a polymer electrolyte.

The lithium battery may further include a separator made of an insulating resin between the cathode and the anode.

Separators made of the above insulating resin are polyethylene separators, polypropylene separators, polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, or polypropylene / polyethylene / polypropylene three layers. It is preferable that it is a separator.

The present invention to achieve the above another technical problem,

Obtaining a composition for forming a polymer electrolyte by mixing a liquid electrolyte solution, a polyfunctional acrylate monomer and a polymerization initiator having a half-life (10 hours) of 90 to 110 ° C;

Stacking a cathode and an anode to form an electrode structure, and storing the same in a battery case; And

It provides a method for producing a lithium battery, characterized in that it comprises the step of heat treatment after injecting the composition for forming the polymer electrolyte to the resultant.

The heat treatment is preferably performed in the range of 40 to 110 ℃.

Separators made of an insulating resin may be further interposed between the cathode and the anode.

The present invention relates to a polymer battery in which a polymer electrolyte is formed by mixing a liquid electrolyte solution, an acrylate monomer and an initiator and thermally polymerizing in a battery, wherein the polymerization rate is controlled by using a peroxide initiator having a half-life temperature of 90 to 110 ° C. Provided are a composition for forming a polymer electrolyte capable of forming a polymer film having excellent chemical properties and physically strong, and a lithium battery employing the same.

Generally, in a polymer battery in which a polymer electrolyte is formed by mixing a liquid electrolyte, an acrylate monomer, and an initiator and polymerizing in a battery, the electrochemical and physical properties of the polymer layer formed after the polymerization directly or indirectly affect battery characteristics. Known as urea, the urea affecting the characteristics of such a chemical gel battery includes liquid electrolyte composition, type of monomer, functional group of monomer, content ratio of liquid electrolyte and monomer, type of initiator, initiator content and reaction temperature.

The present invention provides an initiator which is suitable for polymerization of monomers having a plurality of functional groups among such elements, and which monomers can suppress deterioration of battery characteristics caused by an initiation reaction prior to the polymerization step.

In general, half-life temperatures can be cited as inherent properties of the initiator, and the half-life temperature is typically defined as the temperature at which the polymerization conversion can reach 50% for 10 hours. In the case of such an initiator having a low half-life temperature, a slight initiation reaction may occur even at room temperature, which may cause deterioration of battery performance. By controlling the rate of initiation reaction at a normal polymerization temperature, it is possible to induce the formation of a polymer film having excellent electrochemical properties and physically strong.

In general, the polyfunctional acrylate monomer used to form a polymer electrolyte in a lithium battery has a rapid polymerization reaction. Therefore, when an initiator capable of initiating the reaction at low temperature is used, the size of the polymer gel formed by rapid initiation reaction is increased. It becomes small so that it is difficult to have a three-dimensional network structure capable of sufficiently retaining the liquid electrolyte, but by using the high temperature initiator of the present invention, the rate of initiation reaction can be controlled at a normal polymerization temperature. It is possible to easily form a three-dimensional polymer network structure with improved retention capacity.

Therefore, application of the high temperature initiator according to the present invention may lead to formation of a three-dimensional polymer network structure, retention of sufficient liquid electrolyte, and improvement of electrochemical and physical properties of the polymer film. As a result, the interfacial properties between the cathode and the electrolyte are improved as the properties of the polymer film are improved, thereby reducing the interfacial resistance at room temperature and low temperature. Accordingly, the discharge potential increases at high rate discharge, the discharge capacity is increased, and the service life characteristics. It is possible to induce the improvement of and the improvement of the high temperature swelling characteristic.

The composition for forming a polymer electrolyte of the present invention includes a liquid electrolyte solution, a polyfunctional acrylate monomer and a polymerization initiator, and when the battery is manufactured, they are mixed in the form of a pre-gel solution and then injected into the battery to undergo thermal polymerization at a high temperature. do.

The polymerization initiator used in the composition for forming a polymer electrolyte according to the present invention preferably has a half-life (10 hours) temperature of 90 to 110 ° C., and when the half-life temperature is less than 90 ° C., a high reactivity of the polyfunctional acrylate monomer is used. Because of this, the initiation reaction and various side reactions are more likely to occur at room temperature, and if the half-life temperature exceeds 110 ° C, the polymer electrolyte matrix may not be formed at a normal polymerization temperature, which is not preferable.

The polymerization initiator constituting the composition for forming the polymer electrolyte is more preferably peroxide-based, for example, t-butyl peroxy 3,5,5-trimethyl hexanoate, t-amyl peroxy 3,5,5-trimethyl Hexanoate, t-butyl peroxy acetate, t-butyl peroxy benzoate, 1,1-di-t-butyl peroxy-3,5,5-trimethylcyclo hexane, 1,1-di-t-butyl At least one selected from the group consisting of peroxy cyclohexane, 2,2-di- (t-butyl peroxy) butane and 2,2-bis (4,4-di-t-butyl peroxy cyclohexyl) propane This is preferred.

The liquid electrolyte constituting the composition for forming a polymer electrolyte according to the present invention includes a lithium salt and an organic solvent, and may be used without particular limitation as long as it is commonly used in the manufacture of a lithium battery.

Organic solvents constituting the liquid electrolyte include ethylene carbonate (EC), diethyl carbonate (DEC), γ-butyrolactone (GBL), propylene carbonate (PC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). And diethyl carbonate (DEC) and vinylene carbonate (VC), in which case 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, 2-fluorobenzene It may further comprise at least one fluorinated aromatic hydrocarbon compound selected from the group consisting of, 3-fluorobenzene and 4-fluorobenzene.

Examples of the lithium salt constituting the liquid electrolyte include LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, at least one selected from the group consisting of LiPF ₆ , LiBF ₄ preferably.

And the concentration of the liquid electrolyte consisting of a lithium salt and an organic solvent is preferably 0.6 to 1.5M.

In the composition for forming a polymer electrolyte according to the present invention, the polyfunctional acrylate monomer may be used without particular limitation as long as it is commonly used in the manufacture of a lithium battery, for example, alkyl acrylate esters, urethane acrylates, At least one selected from the group consisting of acrylamide, styrene, N-vinyl amide, and alkylvinyl ether may be used, and the content thereof is preferably 1 to 10 parts by weight based on 100 parts by weight of the liquid electrolyte. . If the content of the monomer is less than 1 part by weight, it is difficult to form a sufficient polymer gel. If the content is more than 10 parts by weight, it is not preferable because of problems such as a decrease in lithium ion conductivity in the polymer electrolyte.

In the composition for forming a polymer electrolyte according to the present invention, the polymerization initiator is preferably used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the multifunctional acrylate monomer. If the content is less than 0.1 parts by weight, it is difficult to play a sufficient role as an initiator, and if it exceeds 20 parts by weight, the effect due to the additional content is less economically undesirable.

The composition for forming a polymer electrolyte used in the lithium battery of the present invention includes a liquid electrolyte solution, a polyfunctional acrylate monomer and a polymerization initiator as described above, and is used by mixing them in the form of a pre-gel solution when the battery is manufactured. .

The present invention the cathode to achieve another technical problem of the present invention; Anode; And it is interposed between the cathode and the anode and provides a lithium battery comprising a polymer electrolyte obtained by the composition for forming a polymer electrolyte according to the present invention.

The cathode and the anode may be prepared according to a conventional method used in manufacturing a lithium battery, wherein the cathode active material is a lithium metal composite oxide, a transition metal compound, a sulfur compound, etc., the anode active material lithium metal, carbon Material, graphite, etc. are used.

Subsequently, an electrode structure including the cathode and the anode is formed, and then housed in a battery case, and the polymer electrolyte forming composition according to the present invention is injected therein, followed by heat treatment at high temperature, thereby completing the lithium battery of the present invention.

In the manufacturing process, the lithium battery of the present invention may further include a separator made of an insulating resin between the cathode and the anode.

Separators made of the above insulating resin are polyethylene separators, polypropylene separators, polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, or polypropylene / polyethylene / polypropylene three layers. It is preferable that it is a separator.

The lithium battery of the present invention manufactured according to the above-described method may be both a lithium primary battery and a lithium secondary battery, and the forms thereof may be both cylindrical and rectangular.

Example 1

1 g of trimethylolpropane triacrylate in 30 g of a mixed solvent of 1.3 mol / liter LiPF6 dissolved in EC and DEC (weight ratio is 3: 7), t-butyl peroxy 3,5,5-trimethyl hexanoate as an initiator (Half-life temperature: 100 ° C.) 0.05 g was mixed to prepare a pre-gel solution.

A slurry was prepared by mixing 3% by weight of polyvinylidene fluoride, 94% by weight of C-10 (Japan Chemical Co., Ltd.), and 3% by weight of Superpie to 50 g of N-methylpyrrolidone (NMP). The cathode was prepared by coating on a 150 μm thick layer. An anode was prepared by mixing 90% by weight of menocarbon fiber (Petoca) and 10% by weight of polyvinylidene fluoride 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 then wound and stored in a battery case. Subsequently, an appropriate amount of the above-mentioned pre-gel solution is injected into the battery case, and the mixture is left at room temperature for about 48 hours to uniformly distribute the pre-gel solution in the battery, and then heated at a temperature of 70 ° C. for 2 hours. The lithium secondary battery was completed by carrying out thermal polymerization.

Example 2

1 g of trimethylolpropane triacrylate and 1.3 g of t-butyl peroxy 2-ethylhexyl carbonate (half life temperature: 30 g) of a mixed solvent of EC and DEC in which 1.3 mol / liter of LiPF ₆ are dissolved (weight ratio is 3: 7) 98 ° C.) 0.05 g were mixed to prepare a pre-gel solution.

A slurry was prepared by mixing 3% by weight of polyvinylidene fluoride, 94% by weight of C-10 (Japan Chemical Co., Ltd.), and 3% by weight of Superpie to 50 g of N-methylpyrrolidone (NMP). The cathode was prepared by coating a 150 μm thick onto the. An anode was prepared by mixing 90% by weight of menocarbon fiber (Petoca) and 10% by weight of polyvinylidene fluoride, 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 then wound and stored in a battery case. Subsequently, an appropriate amount of the above-mentioned pre-gel solution is injected into the battery case, and the mixture is left at room temperature for about 48 hours to uniformly distribute the pre-gel solution in the battery, and then heated at a temperature of 70 ° C. for 2 hours. The lithium secondary battery was completed by carrying out thermal polymerization.

Comparative example

To 30 g of a mixed solvent of 1.3 mol / liter LiPF6 in which EC and DEC are dissolved (weight ratio is 3: 7), 1 g of trimethylolpropane triacrylate and 0.05 g of an initiator benzoyl peroxide (half-life temperature: 72 ° C.) are mixed free. -Gel solution was prepared.

A slurry was prepared by mixing 3% by weight of polyvinylidene fluoride, 94% by weight of C-10 (Japan Chemical Co., Ltd.), and 3% by weight of Superpie to 50 g of N-methylpyrrolidone (NMP). The cathode was prepared by coating a 150 μm thick onto the. An anode was prepared by mixing 90% by weight of menocarbon fiber (Petoca) and 10% by weight of polyvinylidene fluoride, 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 then wound and stored in a battery case. Subsequently, an appropriate amount of the above-mentioned pre-gel solution is injected into the battery case, and the mixture is left at room temperature for about 48 hours to uniformly distribute the pre-gel solution in the battery, and then heated at a temperature of 70 ° C. for 2 hours. The lithium secondary battery was completed by carrying out thermal polymerization.

For the lithium secondary batteries obtained in Examples 1, 2 and Comparative Examples, high-rate discharge characteristics, -20 ° C interface resistance, and 100 times life characteristics were measured, and are shown in Table 1 below.

TABLE 1

High rate discharge characteristic (2C) -20 ℃ Interface Resistance (ohm) 100 lifespan (%) Discharge Capacity (mAh) Discharge voltage (mV) Example 1 717 3585 16 96.9 Example 2 714 3590 16 96.3 Comparative example 710 3438 30 42.6

As described in Table 1, the batteries of Examples 1 and 2, which are lithium secondary batteries of the present invention manufactured by using a high temperature initiator, have a decrease in interfacial resistance and a rise in discharge voltage and discharge capacity at high rates, The effect of the reduction in life deterioration is shown.

The present invention provides a composition for forming a polymer electrolyte capable of forming a polymer film having excellent electrochemical properties and physically strong polymer film by controlling a polymerization rate by using a high temperature initiator, and a lithium battery employing the same.

Claims (24)

0.1 to 20 parts by weight of half-life (10 hours) temperature of 90 to 110 parts by weight of liquid electrolyte, 1 to 10 parts by weight of polyfunctional acrylate monomer and 100 parts by weight of polyfunctional acrylate monomer, based on 100 parts by weight of the liquid electrolyte A composition for forming a polymer electrolyte, comprising a polymerization initiator which is ℃. The composition according to claim 1, wherein the polymerization initiator is a peroxide initiator. The method of claim 2, wherein the polymerization initiator is t-butyl peroxy 3,5,5-trimethyl hexanoate, t-amyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy acetate, t -Butyl peroxy benzoate, 1,1-di-t-butyl peroxy-3,5,5-trimethylcyclo hexane, 1,1-di-t-butyl peroxy cyclohexane, 2,2-di- ( at least one member selected from the group consisting of t-butyl peroxy) butane and 2,2-bis (4,4-di-t-butyl peroxy cyclohexyl) propane. The polyfunctional acrylate monomer of claim 1 is at least one selected from the group consisting of alkyl acrylates, urethane acrylates, acryl amides, styrenes, N-vinyl amides, and alkyl vinyl ethers. A composition, characterized in that. delete delete The composition according to claim 1, wherein the liquid electrolyte solution contains an organic solvent and a lithium salt. The method of claim 7, wherein the lithium salt constituting the liquid electrolyte is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI The composition characterized by the above. The method of claim 7, wherein the organic solvent constituting the liquid electrolyte is ethylene carbonate (EC), diethyl carbonate (DEC), γ-butyrolactone (GBL), propylene carbonate (PC), dimethyl carbonate (DMC), methyl At least one selected from the group consisting of ethyl carbonate (MEC) and diethyl carbonate (DEC) and vinylene carbonate (VC). Cathode; Anode; And A lithium battery interposed between the cathode and the anode and comprising a polymer electrolyte obtained by the composition for forming a polymer electrolyte according to any one of claims 1 to 9. The lithium battery according to claim 10, wherein the lithium battery further comprises a separator made of an insulating resin between the cathode and the anode. The separator according to claim 11, wherein the separator made of the insulating resin is a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator or a polypropylene / It is a polyethylene / polypropylene three-layer separator. The lithium battery characterized by the above-mentioned. Obtaining a composition for polymer electrolyte formation by mixing a liquid electrolyte solution, a polyfunctional acrylate monomer and a polymerization initiator having a half-life (10 hours) of 90 to 110 ° C; Stacking a cathode and an anode to form an electrode structure, and storing the same in a battery case; And Injecting the composition for forming the polymer electrolyte into the resultant comprising the step of heat treatment. The production method according to claim 13, wherein the polymerization initiator is a peroxide initiator. The method of claim 14, wherein the polymerization initiator is t-butyl peroxy 3,5,5-trimethyl hexanoate, t-amyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy acetate, t -Butyl peroxy benzoate, 1,1-di-t-butyl peroxy-3,5,5-trimethylcyclo hexane, 1,1-di-t-butyl peroxy cyclohexane, 2,2-di- ( and t-butyl peroxy) butane and 2,2-bis (4,4-di-t-butyl peroxy cyclohexyl) propane. The method of claim 13, wherein the multifunctional acrylate monomer is at least one selected from the group consisting of alkyl acrylates, urethane acrylates, acryl amides, styrenes, N-vinyl amides, and alkyl vinyl ethers. Production method characterized in that. The method according to claim 13, wherein the multifunctional acrylate monomer is 1 to 10 parts by weight based on 100 parts by weight of the liquid electrolyte. The method according to claim 13, wherein the polymerization initiator is 0.1 to 20 parts by weight based on 100 parts by weight of the multifunctional acrylate monomer. The production method according to claim 13, wherein the liquid electrolyte solution contains an organic solvent and a lithium salt. The method according to claim 19, wherein the lithium salt constituting the liquid electrolyte is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI The manufacturing method characterized by the above. The method of claim 19, wherein the organic solvent constituting the liquid electrolyte is ethylene carbonate (EC), diethyl carbonate (DEC), γ-butyrolactone (GBL), propylene carbonate (PC), dimethyl carbonate (DMC), methyl At least one selected from the group consisting of ethyl carbonate (MEC) and diethyl carbonate (DEC) and vinylene carbonate (VC). The method of claim 13, wherein the heat treatment temperature is in the range of 40 to 110 ℃. The manufacturing method according to claim 13, further comprising a separator made of an insulating resin between the cathode and the anode. The separator according to claim 23, wherein the separator made of the insulating resin is a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator or a polypropylene / A polyethylene / polypropylene three-layer separator.