TW543213B - Lithium polymer secondary cell - Google Patents

Abstract

A lithium polymer secondary cell is provided, which comprises a negative electrode containing a carbonaceous material as an active material, a lithium ion conducting polymer electrolyte layer and a positive electrode containing at least a metal oxide containing lithium as an active material, wherein the polymer electrolyte layer comprises a polymer prepared by polymerizing a terminal (meth)acrylate of a polyether polyol containing an ethylene oxide (EO) unit only or both an EO unit and a propylene oxide (PO) unit in the polymer chain thereof with two types of thermal polymerization initiators having different half-times from each other.

Description

543213 A7 B7 V Technical Field The present invention relates to a lithium polymer secondary battery. In more detail, the present invention relates to a lithium polymer secondary battery which has excellent cycle characteristics and can be produced at a high yield. Prior art Lithium secondary batteries have been developed and researched actively as power sources such as portable electronic devices because they have a very high theoretical energy density compared to other batteries, and they can be made smaller and lighter. However, with the high performance of portable electronic devices, there is a demand for lighter weight and thinner. In addition, for mobile phones and other devices, the reliability and safety of repeated charging and discharging cycles are required. β Until now, lithium secondary batteries have used an electrolyte formed by dissolving a lithium salt in an organic solvent as the electrolyte between the positive electrode and the negative electrode, and iron and aluminum cans have been used to maintain the reliability of the leakage. Its outer packaging material. Therefore, the weight and thickness of the secondary battery are limited by the weight and thickness of the metal can of the outer packaging material. Therefore, the development of lithium polymer secondary batteries that do not use a liquid electrolyte is being actively pursued. This battery makes it easier to seal the battery because the electrolyte is solid, and its outer packaging material can be a very thin and thin material such as an aluminum laminate film, so it can be a lighter and thinner battery. The lithium polymer secondary battery uses a lithium ion conductive polymer or a lithium ion conductive colloid as its electrolyte. For example, Japanese Patent Application Laid-Open No. 4-206156 also discloses a technology that uses a thermal polymerization initiator and a photopolymerization initiator together. First, it is selected by a photopolymerization method. -4- The paper size applies Chinese National Standard (CNS) A4. Specifications (210X297 mm)

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The surface film on the surface of each battery element is hardened in nature, and then the entire colloid is hardened by a thermal polymerization method, thereby making it easier to block the battery. However, in order to harden the ion-conducting colloid, a thermal polymerization and a photopolymerization step are required, and it is desired to improve the productivity. Beer, the so-called «legal to make ionic colloidal technology is also disclosed in, for example, Japanese Unexamined Patent Publication n-mow, Japanese Unexamined Patent Publication, Japanese Unexamined Patent Publication 2000-6740, and Japanese Unexamined Patent Publication 2000 (M) 〇〇246, etc. These publications are intended to improve the productivity of polymer batteries, but it is more desirable to improve the cycle characteristics of polymer secondary batteries. DESCRIPTION OF THE INVENTION According to the present invention, a lithium polymer secondary battery can be provided. It comprises a negative electrode using a shellfish material as an active material, a lithium ion conductive polymer electrolyte layer and at least a lithium oxide-containing metal oxide as an active material, wherein the polymer of the polymer electrolyte layer is Thermal polymerization initiators with different half-life temperatures to polymerize polyethers that contain either ethylene oxide (E0) monomer alone in the polymer chain, or both E0 monomer and propylene oxide (p〇) monomer Formed by the terminal (a) propionic acid of polyhydric alcohol. According to the present invention, the electrolyte layer is first formed by a thermal polymerization initiator with a low half-life temperature, and the interface between the positive electrode active material and the negative electrode active material And polymer electrolyte layer body skeleton. Afterwards, a high half-life temperature thermal polymerization initiator is used to thermally polymerize (thermally bridging) the electrolyte layer / electrode active material interface and the unreacted (a) propionate outside the polymer electrolyte layer skeleton. This result can significantly reduce the electrolyte dryness at the electrolyte layer / electrode active material interface. -5- The paper size is suitable for domestic standards (CNS) A4 specifications _ x 297 public love) 543213 A7 B7

V. Description of the invention (thirsty, and improve the long-term cycle characteristics of lithium polymer secondary batteries. In addition, because the polymer layer of the electrolyte layer / electrode active material interface is first formed ^ the matrix of the decomposed layer body, it can also suppress the polymer II Secondary battery packs are cluttered and improve battery production yield. A brief description of the schematic diagrams of the charge and discharge cycles in the example 4 and the comparative example 2 is shown in the diagram. Embodiment In the peak compound secondary battery of the present invention, an organic peroxide is preferably used for thermal polymerization. In the organic peroxide, 1Q = a low-temperature substance having a temperature of about 30 to 5 (rc, such as isobutyl) Fermented peroxide, bis (decadecyloxy), diisoT-based benzene, α-cumyl peroxy new dodeca, di-η · phenylperoxydicarbonate, diisopropylperoxydicarbonate Vinegar, 1,1,3,3 · tetramethylbutylperoxyneodecane, bis (4_τ_butylcyclohexyl) peroxo-carbamate, cyclohexyl small methylperoxyneodecane @ Purpose 、 双 _ 2 • Ethoxyethylperoxydicarbonate, _ (2-ethylhexylperoxy) diazaco, t_hexylperoxyneodecane, dimethoxybutylperoxydicarbonate Examples of vinegar, bis (3-methyl_3_methoxybutylperoxy) dicarbon_, t_butylperoxy neodecyl ester, etc. In addition, the W-hour half-life temperature is a high temperature substance of 50 to 8 (rc) For example, 3'5-monomethylhexanoxyl peroxide, m-tolyloxy-benzene peroxide (methyl) hydrazone, t-heXylperOxypivalate, lauryl peroxide, stearyl peroxide, etc., at least two kinds can be used Low temperature substance and high temperature substance with 10-hour half-life temperature. The combination is not limited by the above-mentioned initiator. In the lithium polymer secondary battery of the present invention, the polymer electrolyte used is _ -6- this paper is applicable @a 家 标准 (CNS) A4 specification⑽X297 public love) 543213 A7 B7 Five inventions description (4 The above-mentioned thermal polymerization initiator is used to bridge the polymer chain containing E0 monomer alone, or E0 monomer and P0 monomer It is formed by the terminal (a) propionate of two kinds of polyether polyols and exhibits high ion conductivity over a wide temperature range. Also, in the lithium polymer secondary battery of the present invention, The polymer component of the polymer electrolyte is a polyether part and a three-dimensional bridge structure. It is preferred that the polymer is a polyfunctional group. The typical polymer is an ester of polyether polyol with acrylic acid or methacrylic acid (collectively referred to as "(form) propionic acid") It is known that the polyether polyol is obtained by additionally polymerizing ethylene oxide alone or propylene oxide in polyols such as ethylene glycol, glycerin, and trimethylolpropane as starting materials. It can also be copolymerized. Multifunctional polyether polyol poly (ii) propionate, combined with single or monofunctional polyether polyol poly (ii) acrylate. Especially when the polymer electrolyte is a colloidal electrolyte containing an organic electrolyte Next, a trifunctional polyether polyol poly (methyl) propionate having a three-dimensional bridge structure is easily obtained. The bridge body has superior liquid retention of electrolyte. In the lithium polymer secondary battery of the present invention, examples of the organic solvent that can be used for the colloidal electrolyte include cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC); Chain carbonates such as methyl ester (DMC), diethyl carbonate (DEC), ethyl methyl ester (EMC); lactones such as γ-butyrolactone (GBL); methyl propionate, propyl Esters such as ethyl acetate; tetrahydrofuran and its derivatives, M-dimethoxybutane, 1,3-dimethoxybutane, 1,3-dioxane, 1,2-di Ethers such as methoxyethane and methyl di-linear polyether; nitriles such as acetonitrile and benzonitrile; dioxapentane and its paper dimensions are applicable to China National Standard (CNS) A4 specifications (210X 297 (Mm)

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543213 A7 B7 The description of the five inventions (derivatives; cyclamate and its derivatives, etc.) Especially when carbonaceous materials are used as the negative electrode active material, in order to reduce the decomposition of the electrolyte generated by this, at least It is better to contain EC, and to improve its low-temperature characteristics, it is better to contain at least GBL. In addition, it can produce a uniform colloid electrolyte with good compatibility with polyether polyol (meth) acrylic acid ester. In addition, it improves the colloid electrolyte to make it porous Because the permeability inside the pores of the electrode, it is preferable to add 2 to 5% by weight of 1,4-dimethoxybutane and / or 1,3-dimethoxybutane for the entire organic solvent. The lithium salt used as a solute in the lithium polymer secondary battery of the invention is LiC104, LiBF4, LiPF6, LiCF3S03, LiN (S02CF3) 2, LiN (COCF3) 2, LiC (S02CF3) 3, and these compositions can be used. For the entire organic solvent, the lithium salt concentration is preferably 0.8 to 2.5 mol / 1. If the salt concentration is less than 0.8 mol / 1, it is difficult to obtain sufficient ion conductivity in order to obtain high-load battery discharge characteristics. And a salt concentration higher than 2.5 mol / 1 In this case, not only the cost of the lithium salt becomes high, but it takes a very long time to dissolve it, so it is not suitable industrially, so it is not ideal. Polyether polyol (meth) acrylate and the organic electrolyte that dissolves the lithium salt in the organic solvent mentioned above The mixing ratio is the ratio of the mixture to form an ion-conducting colloidal electrolyte after polymerization, and the organic electrolyte in it to form a continuous phase, and the electrolyte separation does not bleed out after a period of time. Specifically, by the weight of the polymer / electrolyte The ratio can be achieved in the range of 20/80 to 2/98. Furthermore, in order to obtain sufficient ion conductivity, it is preferably in the range of 5/95 to 2/98. The polymer electrolyte of the present invention is capable of being dissolved in Pioneer obtained by dissolving lithium polymer in the organic electrolyte of the above-mentioned organic solvent to dissolve the above-mentioned polymer component. -8- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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In the body solution, add 50 ~ 1000 ppm of a thermal polymerization initiator with a low 10-hour half-life temperature, 50 ~ 1000 ppm of a thermal polymerization initiator with a 10-hour half-life temperature and a temperature of 30-80 ° C. Polymerization at temperature for 2 to 80 hours. In the remote case, the half-life temperature of the thermal polymerization initiator having a lower half-life temperature of 10 hours is 30 ~ 50. On the other hand, the thermal polymerization initiator having a high H) hour half-life of ½ degree has a half-life temperature of 50 to 80 ° C, and its activation energy is preferably 30 Kcal / mol or less. If the activation energy is higher than 30 hrs and the half-life temperature is higher than that of coffee, the thermal effect on other ea power components will become greater, and the reliability of the battery itself will be reduced, which is not good. If the 10-hour half-life temperature is lower than 30 ° C, the penis 7 A,% is lower than the preservation property of the heat-encouraging agent, so it is not good. The activation energy is 25 Kcal / m0i or less ^ ° Poor storage stability and battery performance are disturbed, so it is not good. 'words'

The battery of the present invention is a negative ion-conducting colloidal electrolyte layer prepared in advance, and the two are overlapped or polarized to form a positive electrode to place a separation substrate, and then the polymer is injected into the negative electrode and the medium, the lithium salt and The solution of the thermal polymerization initiator is mixed with organic solvents, but it is not limited to this. When the separation substrate can be used from icing, 'for the substrate can be chemically stable in the organic electrolyte such as polypropylene, such as polyethylene, polyethylene film, and the film of these polymer fibers (Paper, non-woven micron porous substrates are air-permeable households with 1 ~ 500 sec / cm3, nm temple is preferred. These are due to continuous maintenance of the company ’s internal resistance, and they have only low battery prevention ~~ < The strength is that the carbonaceous material capable of using the negative electrode active material according to the present invention is preferably a material capable of inserting / extracting the warp. In particular, for: aerochemical, ... ~ Λ / extraction potential, the paper size is applicable to China National Standard (CNS) A4 specification (210X 297 mm) 543213 A7 B7 Five inventions description (Near the precipitation / dissolution potential of lithium metal, it is better to form a high energy density battery. The typical is natural or artificial granular ( Scale-like, massive, fibrous, whisker-like, spherical, pulverized particles, etc.) graphite is preferred. Graphitized metastable phase spherical carbon, metastable phase asphalt powder, isodirectional asphalt powder, etc. can also be used. Artificial graphite. As better Examples of carbonaceous materials are graphite particles with amorphous carbon adhered to the surface. As an example of the attachment method, graphite particles are immersed in tar, heavy green oil, or heavy petroleum oil such as heavy oil, and then picked up. A method to decompose heavy oil by heating it above the carbonization temperature. After attaching, the same carbonaceous material can be pulverized if necessary. The graphite particles with amorphous carbon attached to the surface are intentionally suppressed from being charged at the negative electrode during charging. The decomposition reaction of organic solvent and lithium salt occurs. Therefore, the cycle life of charge and discharge can be improved, and the petroleum gas generated by the same decomposition reaction can be suppressed. In addition, the carbonaceous material of the present invention is measured by the BET method. The pores with a specific surface area are as large as can be blocked by the attachment of amorphous carbon. The specific surface area is preferably in the range of 1 to 5 m2 / g. If the specific surface area is larger than this range, it will be in contact with the dissolved lithium salt. The contact area of the organic electrolyte of the organic electrolyte becomes large, and its decomposition reaction easily occurs, which is not good. In addition, the absorption of the thermal polymerization initiator that forms the polymer electrolyte layer on the negative electrode is not good. If the amount is increased, the bridge that hinders the polymer electrolyte is not good. If the specific surface area is smaller than this range, the contact area with the electrolyte becomes smaller, the electrochemical reaction is slowed, and the load characteristics of the battery are lowered. A lithium-containing metal oxide is used as the active material of the positive electrode. In particular, at least one of Lia (A) b (B) e02 is selected (here, A is one or two or more transition metal elements. B is From the Periodic Table-10- This paper size applies Chinese National Standard (CNS) A4 (210 X 297 mm) binding

543213 A7 B7 Five invention descriptions (IIIB, IVB and VB non-metallic elements and semi-metallic elements, alkaline earth metals, Zn, Cu, Ti and other metal elements, one or more elements selected. a, b, and c are each a composite oxide of a layered structure represented by 0 < α < 1 · 15, 0.85U + K1.30, 0 < c), or a composite oxide containing a spinel structure. . These metal oxides are preferred because they can promote the reaction effect of the thermal polymerization initiator of the organic oxide. Examples of representative lithium-containing composite oxides are LiCo02, LiNi02, LiMn20, LiCoxNiNxO2 (0 < x < l), and LiNibxMxOK (but M is a transition metal element). When using these carbonaceous materials for the negative electrode active material, even if the voltage changes with the carbonaceous material itself (approximately 1 Vvs. Li / Li +), it can fully display its practical operating voltage. In addition, Li ions necessary for charging and discharging the battery are already contained in the battery in a state such as LiCo〇2 and LiNi〇2 before the battery is assembled. The positive electrode and the negative electrode are formed by fixing a positive electrode and a negative electrode active material with a binder to form respective active material layers, and using these active material layers as a current collector on a metal foil. Examples of the material of the metal foil of the current collector include aluminum, stainless steel, titanium, copper, and nickel. Among these, in consideration of electrochemical stability, extensibility, and economy, aluminum foil for the positive electrode and copper foil for the negative electrode are preferred. In addition, the main positive electrode and negative electrode current collectors shown in the present invention are in the form of metal foil, but as other types, they are exemplified by meshes, expanded metals, wire cloth (mesh) bodies, porous bodies, or resin films. , Covering the electron conductive material but not limited to this. -11-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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543213 A7 B7 Fifth invention description (when making positive and negative electrodes, graphite, carbon black, acetylene black, kechen black, carbon fiber, conductive metal oxide and other chemically stable conductive materials can be used if necessary Combination with active materials. This use can improve electron conduction. Also, when making positive and negative electrodes, because the binder is chemically stable and can be dissolved in a suitable solvent, it does not offend the thermoplastic resin of the organic electrolyte. Most of the resins are known, but it is preferred to use polyvinylidene fluoride (PVDF), such as N-methyl-2-pyrrolidone (NMP), which is selectively soluble in organic solvents, but stable to organic electrolytes. ). Other thermoplastic resins that can be used are, for example, acrylonitrile, methacrylonitrile, fluorinated acetamidine, chloroprene, acetamidine and its derivatives, vinylidene chloride, ethylene, acetam, Polymers and copolymers such as cyclodyne (such as cyclopentafluorene, 1,3-cyclohexadiene, etc.). Instead of a solution, a dispersion of a binder resin may be used. When the electrode is an active material, it can be used with Adhesive for conductive material The solution of the mixture resin is kneaded to make a paste, and it is coated with a uniform thickness on a metal foil using an appropriate applicator. After drying, it is made by pressing. The proportion of the binder in the active material layer should be The minimum required is generally 1 to 15 parts by weight. In the case of using a conductive material, the amount of conductive material is generally 2 to 15 parts by weight of the active material layer. The electrodes produced in this way are integrated to form ions. The conductive colloidal electrolyte layer and the electrode active material layer are the same, and the ion conductive colloidal layer is a substance containing an organic electrolyte that impregnates or holds a lithium salt in the ion conductive polymer matrix. It is solid in appearance, but -12- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) binding

543213 A7 B7 V. Explanation of the invention () Microscopically, the lithium salt solution forms a continuous phase, which has a higher ionic conductivity than the ion-conductive polymer electrolyte without a solvent. The ion-conducting colloidal electrolyte layer is formed by polymerizing a polymer matrix polymer and a lithium salt-containing organic electrolytic solution by respective thermal polymerization and photopolymerization methods. The battery can be made of nickel-iron-iron and aluminum-made cylindrical cans, angle cans, or aluminum foil. The batteries are not limited to these materials. (Examples) The following examples are for the purpose of illustration and do not represent the limitations of the present invention. (Example 1) The battery of Example 1 was produced in the following steps. a) The negative electrode is prepared by mixing 100 parts by weight of carbon material powder (average particle size: 12 μm, specific surface area: 2 m2 / g) with amorphous carbon on the surface of graphite particles in a weight ratio of 100: 9, and a binder PVDF, Add an appropriate amount of NMP as a solvent and knead it to obtain a negative electrode material paste. This was coated on a 18 μm Cu foil, dried, and pressed to obtain a negative electrode sheet. The negative electrode sheet was cut into 30 × 30 mm, and the nickel current collector was dissolved to obtain the negative electrode. b) The positive electrode is made by mixing LiCo02 100 parts by weight with an average particle size of 7 μm, 5 parts by weight of carbon black with conductive material and 5 parts by weight of PVDF as a binder, and adding an appropriate amount of NMP as a solvent and kneading, that is, A positive electrode paste was obtained. Apply it to -13- This paper size applies Chinese National Standard (CNS) A4 specification (210X 297 mm) 543213 A7 B7 Five invention instructions (A1 foil of 20 μm), after drying, it is pressed to obtain a positive electrode sheet. Cut the positive electrode sheet into 30 X 30 mm and dissolve the A1 current collector to obtain the positive electrode. C) The polymer electrolyte precursor solution was prepared by mixing 50:50 volume ratio solvent of EC and GB to dissolve LiBF4 to 2 mol / Concentration of 1 to obtain an organic electrolyte. A trifunctional polyether polyol methacrylate having a molecular weight of 7,500 to 9000 was mixed with 3.5% by weight, and a monofunctional polyether polyol acrylate having a molecular weight of 220 to 300 was 1.5% by weight, and 95% by weight of the organic electrolytic solution was mixed. In addition, the above solution was added as t-butylperoxyneodecanoate (10 ° C half-life temperature at 47 ° C, activation energy 29 Kcal / mol) 50 ppm and t-butylperoxy as a thermal polymerization initiator. Pentamyl ester (10 ° C half-life temperature of 53 ° C, activation energy 28 Kcal / mol) 100 ppm, the precursor solution can be obtained. d) The battery is assembled on the polyester non-woven fabric (thickness 20 μm, air permeability 180 sec / cm3) between the negative electrode and the positive electrode obtained above, and inserted into the resin film made of A1 as the outer packaging material. The bag was filled with the precursor solution obtained in c), and the bag was sealed. Heat the battery at 60 ° C for 24 hours to complete the battery. (Example 2) The battery of Example 2 was produced in the following steps. a) Fabrication of negative electrode 100 parts by weight of 100: 9 artificial graphite powder (average particle size: 12 μm, specific surface area: 8 m2 / g), 100 parts by weight, and PVDF binder, add NMP as a solvent and mix , To obtain a negative electrode paste. Coat it -14- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) binding

543213 A7 ι_— B7 V. Description of the invention Γ ~-:-

12 J on 18 pm < Cu foil, after being dried, it was pressed into a negative electrode sheet. The negative electrode sheet was cut into 30 × 30 mm, and the nickel current collector was dissolved to obtain the negative electrode. b) Fabrication of the positive electrode: LiNiG.2C0G 802 100 weight parts with an average particle size of 7 μm, 5 weight parts of acetonitrile carbon black with conductive material, 5 weight parts of pvdf of the binder, suitable f Add NM P as a cereal and knead it to obtain the positive electrode material paste. It was coated on A1 foil of 20 μχη, and after being dried, it was pressed to obtain a positive electrode sheet. The positive electrode sheet was cut into 30 × 30 mm, and the Ai current collector was melted to obtain a positive electrode. °) Preparation of the polymer electrolyte precursor solution The mixed solvent of 20: 60 ·· 20 volume ratio of EC and GBL and EMC was used to dissolve LiPF6 to a concentration of L5 mol / 1 to obtain an organic electrolyte. A trifunctional polyether polyol propionate having a molecular weight of 7500 to 9000 was mixed with 2.5% by weight, and a monofunctional polyether polyol having a molecular weight of 2500 to 3000 was 0.5% by weight, and 97% by weight of the organic electrolytic solution was mixed. In addition, to the above solution, α-cumyl peroxyneodedecyl ester (the 10-hour half-life temperature of 38 ° C, the activation energy of 27 Kcal / m〇1) 250 ppm as a thermal polymerization initiator -Tolyloxy-benzene (methyl) peroxide (10-hour half-life temperature at 73 ° C, activation energy 30 Kcal / mol) 500ppm, the precursor solution can be obtained. d) The battery is assembled in the polyethylene microporous membrane (thickness 25 μm, air permeability 380 sec / cm3) with a separation substrate interposed between the negative electrode and the positive electrode obtained above, and inserted into the outer packaging material A1. A bag made of a resin film is poured into the precursor solution obtained in c), and the bag is sealed. Heat treatment at 40 C80 hours -15- This paper size applies to China National Standard (CNS) A4 (210X 297 mm) 543213

V. Description of the invention (that is, the element battery. (Example 3) The following steps are used to make the battery of Example 3. a) The negative electrode is manufactured by mixing artificial graphite powder with a weight ratio of 100: 9 (average). The particle size is 12 μηι, and the specific surface area is 5 mVg ^ OO. The weight part and the binder PvDF are added in an appropriate amount and mixed with NMP as a solvent to obtain a negative electrode material paste. This is coated on a Cu foil of 18 μπι. After drying, it is pressed to obtain a negative electrode sheet. The negative electrode sheet is cut into 30 × 30 mm, and nickel collector is used to obtain the negative electrode. B) The positive electrode is made by mixing 100 parts by weight of LiMn204 with an average particle size of 9 μm, 7 parts by weight of the carbon black of the conductive material and 3 parts by weight of the PVDF of the binder, and an appropriate amount of NMP as a solvent was added and kneaded to obtain a positive electrode material paste. It was coated on 20 μm of A1 foil, and after being dried, it was pressed to obtain a positive electrode sheet. The positive electrode sheet was cut into 30 X 30 mm, and the positive electrode was obtained by welding A1 current collector. c) Preparation of polymer electrolyte precursor solution The mixed solvent of 50:30:20 volume ratio of EC, pC and DEC was used to dissolve LiN (CoCF3) 2 to a concentration of 1.0 mol / 1 to obtain an organic electrolyte. The trifunctional polyether polyol acrylate having a molecular weight of 7500 to 9000 is mixed with 7 weight ° / 〇, and the monofunctional polyether polyol propionate having a molecular weight of 7500 to 9,000 is 3% by weight. 90% by weight. In addition, to the above-mentioned falling liquid, α-cumyl peroxyneododecyl ester (a 10-hour half-life temperature of 38 ° C, an activation energy of 27 Kcal / mol) 100 ppm as a thermal polymerization initiator and 3,5,5_trimethylperoxide (59 ° Ci, 10 hours half-life temperature-16) This paper size applies Chinese National Standard (CNS) A4 specification (21 × 297 mm) 543213 A7 B7 And the activation energy is 30 Kcal / mol) 1000 ppm in this mixture to obtain a precursor solution. D) Assembly of the battery The polypropylene micron porous membrane (thickness 25 μηι) with a separation substrate interposed between the negative electrode and the positive electrode obtained above. , Air permeability 480 sec / cm3), and insert it into a bag made of A1 hammered into a resin film as an outer packaging material, and inject it into the precursor solution obtained in c), and seal the bag. Heat the battery at 80 ° C for 2 hours to complete the battery. (Comparative Example 1) The battery of Comparative Example 1 was produced in the following steps. a) Fabrication of the negative electrode Repeat the same operation as in Example 1 to obtain the negative electrode. b) Fabrication of the positive electrode The same operation as in Example 1 was repeated to obtain the positive electrode. c) Preparation of precursor solution for polymer electrolyte Addition of thermal polymerization initiator t-butylperoxyneodecanate (10-hour half-life temperature at 47 ° C, activation energy 29 Kcal / mol) 50 ppm and benzene peroxide (A) Except for 醯 (10 hour half-life temperature at 74 ° C, activation energy 32 Kcal / mol) 100 ppm, the same operation as in Example 1 can be repeated to obtain the precursor solution. d) Assembly of the battery Repeat the same operation as in Example 1 to complete the battery. (Comparative Example 2) The battery of Comparative Example 2 was produced in the following steps. a) Fabrication of negative electrode -17- This paper size applies to China National Standard (CNS) A4 specification (210X 297 mm)

Binding 543213 A7 B7 5 Description of the invention (Repeat the same operation as in Example 2 to obtain the negative electrode. B) Fabrication of the positive electrode Repeat the same operation as in Example 2 to obtain the positive electrode. c) Preparation of polymer electrolyte precursor solution. Adding only one thermal polymerization initiator is m-tolyloxy-benzene peroxide (methyl)） (10-hour half-life temperature at 73 ° C, activation energy 30 Kcal / mol) Except for 750 ppm, the same operation as in Example 2 was repeated to obtain the precursor solution. d) Assembly of the battery Repeat the same operation as in Example 2 to complete the battery. (Example 4) The battery of Example 4 was produced in the following steps. a) Preparation of negative electrode Repeat the same operation as in Example 3 to obtain the negative electrode. b) Fabrication of the positive electrode The same operation as in Example 3 was repeated to obtain the positive electrode. c) Preparation of polymer electrolyte precursor solution using polymer 8 weight% of 2-functional polyether polyol acrylate with molecular weight 7500 ~ 9000, and 2 weight of monofunctional polyether polyol acrylate with molecular weight 7500 ~ 9000 Except for%, the same operation as in Example 3 is repeated to obtain the precursor solution. d) Battery assembly Repeat the same operation as in Example 3 to complete the battery. All of the batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were filled with a positive electrode active material and a negative electrode active material to have a battery capacity of 20 mAh. With -18- this paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm)

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543213 A7 B7 Five invention descriptions (Charge these batteries with a certain current value of 2.5 mA until the battery voltage becomes 4.1 V, and then charge at a certain voltage until the total charging time is 12 hours after reaching 4.1 V. The battery voltage becomes 2.75 V The discharge is performed at a constant current value of 5 mA. The migration of the discharge capacity when charging and discharging is repeated up to 300 cycles is shown in Fig. 1. As can be seen from Fig. 1, compared with Example 1, The cycle characteristics of the battery of Comparative Example 1 are low. This is because even if two types of thermal polymerization initiators are used, only benzene (曱) 醯 with a high activation energy of 32 Kcal / mol is used as the initiator That is, because the polymerization reaction inside the polymer electrolyte layer is insufficient, the strength of the electrolyte layer itself is also low, and because the unreacted polymer remains in the battery, the cycle characteristics of the lithium polymer secondary battery are deteriorated.

Moreover, compared with Example 2, the cycle characteristics of the battery of Comparative Example 2 were also low. This is because the thermal polymerization initiator with a low half-life temperature of 10 hours is not used, and the interface between the electrode active material / polymer electrolyte layer and the polymer electrolyte layer body is insufficiently formed, which deteriorates the cycle of the lithium polymer secondary battery. characteristic. Next, when comparing Example 1 and Example 2, the lithium polymer secondary battery of Example 1 showed excellent cycle characteristics. This is because the negative electrode active material uses a carbon material powder having amorphous carbon adhered to the surface of graphite particles. That is, because the specific surface area is small, the adsorption amount of the thermal polymerization initiator is reduced, and the skeleton of the electrode active material / polymer electrolyte layer interface and the polymer electrolyte layer body can be fully formed. No residue in the battery. Finally, from the results of Examples 3 and 4, the use of trifunctional polyether poly-19- This paper size applies to China National Standard (CNS) A4 specifications (210 X 297 mm) 543213 A7 B7 V. Description of the invention ( The alcohol acrylate can form the three-dimensional skeleton of the polymer electrolyte layer body, and the strength of the electrolyte layer itself is also high. Since the unreacted polymer does not remain in the battery, the cycle degradation is reduced. 鑤 According to the present invention, it can provide A lithium polymer secondary battery having improved cycle characteristics. In addition, by using a negative electrode active material, an amorphous carbon having a smaller specific surface area than that of graphite particles is adhered to the surface of the graphite particles to reduce adsorption on the carbonaceous material. It can be used as a thermal polymerization initiator to smoothly proceed the polymerization reaction, and as a result, it can provide a lithium polymer secondary battery with superior cycle characteristics.

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Claims (1)

A BCD 543213 6. Scope of patent application 1. A lithium polymer secondary battery comprising a negative electrode using a carbonaceous material as an active material, a lithium ion conductive polymer electrolyte layer, and at least a lithium-containing metal oxide as The positive electrode of an active material, in which the polymer of the polymer electrolyte layer is polymerized through two different half-life temperature thermal polymerization initiators, which are polymerized in the polymer chain and contain ethylene oxide (E0) monomer alone, or contain E0 monomer and propylene oxide (P0) monomer two polyether polyols formed by the terminal (meth) acrylate. 2. The lithium polymer secondary battery according to item 1 of the scope of the patent application, wherein the above-mentioned thermal polymerization initiator has a 10-hour half-life temperature of two kinds and has an activation energy of 30 Kcal / mol or less. 3. Lithium polymer secondary battery according to item 2 of the scope of the patent application, in which the thermal polymerization initiators are selected separately, at a temperature of 30 to 50 ° C and a range of 50 to 80 ° C for a 10-hour half-life temperature. Organic peroxides. 4. The lithium polymer secondary battery according to item 1 of the scope of the patent application, which contains a terminal (a) propionate of a polyether polyol and a trifunctional polyether polyol (曱) acrylate. 5. The lithium polymer secondary battery according to the first patent application scope, wherein the polymer electrolyte layer is a colloidal electrolyte layer containing at least ethylene carbonate (EC) and γ · butyrolactone (GBL). 6. The lithium polymer secondary battery according to item 1 of the application, wherein the carbon material is a carbon material containing at least amorphous carbon adhered to the surface of the graphite particles. 7. The lithium polymer secondary battery according to item 1 of the patent application scope, wherein the metal oxide containing lithium is any of LiCo02, LiNi02, LiMn204, and LiNii-xMxC ^ C (M is a transition metal element). -21-This paper size applies to China National Standard (CNS) A4 (210X297 mm)