WO2020143259A1

WO2020143259A1 - Preparation and application of polycarbonate-based polymer electrolyte

Info

Publication number: WO2020143259A1
Application number: PCT/CN2019/110925
Authority: WO
Inventors: 尉海军; 林志远; 郭现伟
Original assignee: 北京工业大学
Priority date: 2019-01-10
Filing date: 2019-10-14
Publication date: 2020-07-16
Also published as: CN109802174B; CN109802174A

Abstract

Preparation and application of a polycarbonate-based polymer electrolyte, relating to the technical field of lithium-ion batteries. In the present invention, vinyl ethylene carbonate, a conductive lithium salt, a porous support material, and a solvent are used to prepare a polymer electrolyte. The preparation process for the polymer electrolyte is simple and easy to control; the polymer electrolyte has excellent mechanical properties, a thickness of 50-500 μm, an ion conductivity greater than 10^-3Scm^-1 at room temperature, and an electrochemical window greater than 4.7 V; the polymer electrolyte can effectively inhibit the growth of lithium negative electrode dendrites, and improves compatibility with an interface and long cycle performance; a solid-state lithium-ion battery can work for a long time at room temperature. In addition, the polymer electrolyte has good flexibility and is also suitable for a flexible lithium-ion battery device of a wearable electronic device.

Description

Preparation and application of polycarbonate-based polymer electrolyte

Technical field

The invention relates to the field of polymer electrolytes for lithium-ion batteries, in particular to the preparation of a new polycarbonate-based polymer electrolyte and its application in solid-state lithium-ion batteries, and belongs to the technical field of lithium-ion batteries.

Background technique

In recent years, lithium-ion batteries have become more widely used due to their high energy density and good reliability. However, most commercial batteries use conventional organic liquid electrolytes, such as ethylene carbonate and propylene carbonate. Because organic electrolytes usually have high chemical activity, volatility, easy to catch fire, explosion and other safety defects, it has seriously hindered the further popularization and application of lithium ion batteries. In addition, when metal lithium is used as the negative electrode, during the operation of the liquid battery, with the continuous insertion and extraction of lithium ions, lithium dendrites will be generated on the surface of the metal lithium. The generation of lithium dendrites not only causes the appearance of dead lithium regions, reduces the cycle performance of the battery, but also pierces the separator, causing a short circuit of the battery, which severely limits the development and application of high energy density lithium metal batteries. Therefore, the development of solid electrolytes to replace traditional liquid electrolytes is of epoch-making significance for the development of high energy density lithium metal batteries. For inorganic solid electrolytes, the preparation process is complicated and the interface compatibility is poor. The polymer electrolyte is obtained due to the advantages of good compatibility with lithium metal, high thermal stability, simple preparation process, good flexibility and adjustable shape and size. Widely recognized. The ideal polymer electrolyte should have the following advantages: 1. Close to the ionic conductivity of the liquid electrolyte; 2. Has good compatibility with the electrode; 3. Wide electrochemical window; 4. Simple preparation process. However, it has been difficult for the polymer electrolyte to satisfy the above advantages at the same time.

Polyethylene oxide (PEO), reported by Wright and others in 1973, was confirmed by Armand in 1979, and proposed to be used as an electrolyte material for solid-state batteries, so that the research of polymer electrolytes has entered a new development stage. However, due to the low ionic conductivity of PEO-based polymer electrolytes at room temperature (PEO room temperature conductivity is about 10 ^-7 Scm ^-1 ) and a low electrochemical stability window, it cannot meet market demand and cannot be widely used. Promotion. Although many scholars have carried out physical modification (blending, addition of plasticizers) and chemical modification (graft modification) on PEO, it can improve the ionic conductivity of PEO to a certain extent (room temperature can reach 10 ^-5 ～10 ^-4 S cm ^-1 ), but there are still low electrochemical windows and interface problems. Therefore, many scholars are devoted to the development of a new type of polymer electrolyte, which contains a strong polar carbonate group [-O-(C=O)-O-] polymer has attracted wide attention of researchers. Patent No. CN105591154A provides a polycarbonate-based all-solid polymer electrolyte, the polymer electrolyte has an ion conductivity of 2×10 ^-5 S cm ^-1 ～1×10 ^-3 S cm ^-1 at room temperature, and the electrochemical window is greater than 4V. In addition, the patent number CN 105702919A provides a method for preparing a lithium battery electrode containing an interface-stable polymer material and its application in a solid-state lithium battery. Polyvinyl carbonate (PVCA) or its copolymer is used to prepare a polymer electrolyte, which can form a covering film on the surface of the electrode, which can effectively suppress the destruction of the electrode material and the decomposition of the solid electrolyte on the surface of the positive and negative electrodes during the charging and discharging process. These two carbonate-based polymer electrolytes have high ionic conductivity and good interfacial stability, but the electrochemical window is low (<4.7V), which is not suitable for high nickel cathode material systems.

In response to the above problems, we have developed a new polycarbonate-based polymer electrolyte, which uses ethylene carbonate, lithium salt, porous support materials and solvents to prepare polymer electrolytes. The preparation process of the polymer electrolyte is simple, easy to control, and has excellent mechanical properties; room temperature ion conductivity>10 ^-3 S cm ^-1 , electrochemical window>4.7V; the polymer electrolyte can effectively suppress the lithium anode dendrite Growth, improve compatibility with the interface and long cycle performance; solid-state lithium-ion batteries can work for a long time at room temperature. At the same time, the polymer electrolyte has good flexibility and is also suitable for flexible lithium ion battery devices of wearable electronic equipment.

Summary of the invention

The object of the present invention is to provide a new type of polycarbonate-based polymer electrolyte preparation and its application in solid-state lithium-ion batteries.

The technical solution of the present invention is:

A new type of polycarbonate-based polymer electrolyte, which is characterized by a liquid mixture including a liquid ethylene carbonate, a conductive lithium salt and an organic solvent before crosslinking and curing, to which an initiator or catalyst is added, and a porous support material Immerse in the liquid mixture or apply the liquid mixture to the porous support material, and then solidify to prepare a polymer electrolyte; wherein the composition of each substance in the liquid mixture: ethylene carbonate accounts for the mass fraction of the mixture of 30- 80%, the conductive lithium salt accounts for 10-50% of the mixture, the organic solvent accounts for 1-50% of the mixture, and the initiator (or catalyst) mass fraction is 0.5-5% of ethylene carbonate. .

The preparation of a novel polycarbonate-based polymer electrolyte is characterized in that the structure of ethylene carbonate is as follows:

The novel polycarbonate-based polymer electrolyte is characterized in that the conductive lithium salt is one or more of the following: lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), bistrifluoromethane Lithium sulfonimide (LiTFSI), bis(trifluoromethanesulfonyl)methyl lithium [LiC(SO ₂ CF ₃ ) ₃ ];

The organic solvent is one or more of the following: N-methylpyrrolidone (NMP), ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate Ester, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, 1,2-dimethoxyethane, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether Ether, dimethyl sulfoxide;

The initiator or catalyst is one of the following: dibutyl tin dilaurate, dibutyl tin bis(acetylpyruvate), azobisisobutyronitrile (AIBN), azobisisoheptanonitrile (ABVN), Dimethyl azobisisobutyrate (AIBME), benzoyl peroxide (BPO), platinum water (Pt);

The porous support material is one or more of cellulose nonwoven fabric, polyethylene nonwoven fabric, polypropylene nonwoven fabric, glass fiber nonwoven fabric, and polytetrafluoroethylene nonwoven fabric.

The preparation of a novel polycarbonate-based polymer electrolyte is characterized in that it includes the following steps: the corresponding mass fraction of ethylene ethylene carbonate, conductive lithium salt and organic solvent is formulated into an electrolyte, and the mixture is evenly stirred; Add the corresponding mass fraction of initiator or catalyst and stir evenly; apply or immerse the above electrolyte into the polytetrafluoroethylene mold containing porous support material, heat and cure at 60-120℃ for 2-12 hours to form a film.

The polymer solid-state lithium-ion battery containing the novel polycarbonate-based polymer electrolyte is characterized in that it includes a positive electrode, a negative electrode, and a separator and an electrolyte function between the positive electrode and the negative electrode The above polymer electrolyte of the present invention;

The polymer solid-state lithium-ion battery described above is characterized in that the positive electrode active material is lithium iron phosphate (LiFeO ₄ ), lithium nickel cobalt aluminate (NCA), lithium-rich materials (LLOs), and lithium cobaltate (LiCoO ₂ ), one or more of lithium ion lithium fluorophosphate, lithium nickel cobalt manganate, lithium manganese oxide, lithium manganate, lithium nickel manganate, lithium manganese iron phosphate, lithium nickelate (LiNiO ₂ ); The active material is one or more of lithium metal, lithium metal alloy, carbon-silicon composite material, lithium titanate, graphite, lithium metal nitride, antimony oxide, carbon germanium composite material, and lithium titanium oxide.

The polymer solid-state lithium-ion battery is characterized in that the preparation of the positive electrode includes the following steps: (1) The preparation of the positive electrode material includes the following steps: the positive electrode active material, which accounts for 50-90% of the mass fraction, Grinding and mixing the conductive agent acetylene black with a mass fraction of 5-30%, adding polyvinylidene fluoride (PVDF) with a mass fraction of 1-15%, a mixed liquid of 1-15% electrolyte and 1-methyl-2pyrrolidone (NMP) Grinding and mixing to obtain the positive electrode material, of which 1-methyl-2pyrrolidone (NMP) is used to adjust the viscosity, which is not included in the mass percentage composition of the positive electrode material; (2) The positive electrode material is coated on the surface of the aluminum foil and dried Get positive

Metal lithium and metal lithium alloy can be directly used as the corresponding negative electrode;

Or the preparation of the negative electrode, including the following steps: (1) Preparation of the negative electrode material: grinding and mixing the negative electrode active material with a mass fraction of 30-80% and the conductive agent acetylene black with a mass fraction of 5-30%; adding the mass fraction Grind and mix 5-25% polyvinylidene fluoride (PVDF), 1-15% electrolyte mixture and 1-methyl-2pyrrolidone (NMP) to obtain negative electrode material; of which 1-methyl-2pyrrolidone (NMP) It is used to adjust the viscosity and is not included in the mass percentage composition of the negative electrode material; (2) coated on the surface of the copper foil and dried to obtain the negative electrode.

The composition of the electrolyte mixture in the positive electrode material and the negative electrode material is as follows: the electrolyte mixture liquid component ethylene carbonate accounts for 30-80% of the electrolyte mixture liquid mass fraction, and the conductive lithium salt accounts for the electrolyte mixture liquid mass fraction 10-50%, the mass fraction of organic solvent in the electrolyte mixture is 1-50%, and the mass fraction of the initiator or catalyst is 0.5-5% of the mass of ethylene ethylene carbonate; the specific content of each substance in the electrolyte mixture The selection range is the same as the selection range of each substance of the polycarbonate-based polymer electrolyte raw material described above.

The preparation process of the battery is (1): ex-situ assembly process --- positive electrode, negative electrode and the above solid polymer electrolyte; (2): in-situ assembly process --- injection of the above electrolyte mixture to the positive electrode, The battery system of the separator and the negative electrode is cured at 60-120°C.

The innovation and practicality of the present invention lies in:

In the present invention, for the first time, a mixture of ethylene ethylene carbonate, a conductive lithium salt, a porous support material and an organic solvent is used to prepare a solid polymer electrolyte. The polymer electrolyte has high ionic conductivity (>10 ^-3 S cm ^-1 ), electrochemical window (>4.7V) and thermal stability at room temperature. At the same time, when the polymer electrolyte is assembled into a solid-state lithium ion battery, a protective layer can be formed on the surface of the lithium battery electrode material and metal lithium, which can effectively suppress the destruction of the electrode crystal caused by the insertion and extraction of lithium ions, and thus improve Long cycle stability of lithium batteries. In addition, in the preparation process of the polymer electrolyte of the present invention, an organic solvent may not be added, and a polymer electrolyte is prepared by in-situ polymerization, which eliminates hidden safety hazards and environmental pollution, and greatly improves the safety and practicality of the lithium battery. It can be applied to all-solid lithium batteries (including lithium-sulfur batteries), all-solid lithium-ion batteries, and other secondary high-energy lithium batteries.

BRIEF DESCRIPTION

FIG. 1 is a CV diagram in Preparation Example 2 of a polymer electrolyte.

FIG. 2 is the charge-discharge performance of the lithium-ion battery in Example 7 for preparing a solid-state lithium-ion battery.

detailed description

The following describes the present invention through specific examples. The examples are improved to better understand the present invention, and in no way limit the scope of the present invention.

Preparation of polymer electrolyte:

Example 1

Dissolve 3g of ethylene ethylene carbonate and 0.8g of lithium bistrifluoromethanesulfonimide (LiTFSI) in 5ml of acetonitrile and stir at room temperature to completely dissolve; add 0.1g of azobisisobutyronitrile and stir evenly. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was applied on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Example 2

Dissolve 1g of ethylene carbonate and 0.25g of lithium bistrifluoromethanesulfonimide (LiTFSI) into 1.5ml of N-methylpyrrolidone (NMP), stir at room temperature to completely dissolve; add 0.02g of azobis Isobutyronitrile is evenly stirred. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was applied on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Example 3

Dissolve 1.38g ethylene ethylene carbonate and 0.4g lithium bistrifluoromethanesulfonimide (LiTFSI) in 1.5ml N-methylpyrrolidone (NMP), stir at room temperature to completely dissolve; add 0.02g double ( (Acetylpyruvate) Dibutyltin was evenly stirred. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was coated on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Example 4

Dissolve 1.8 g of ethylene ethylene carbonate and 0.65 g of lithium perchlorate (LiClO ₄ ) in 2 ml of tetrahydrofuran and stir at room temperature to completely dissolve; add 0.02 g of bis(acetylacetonate) dibutyltin and stir uniformly. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was applied on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Example 4

Dissolve 2.3 g of ethylene carbonate and 0.8 g of lithium perchlorate (LiClO ₄ ) in 2 ml of tetrahydrofuran and stir at room temperature to completely dissolve; add 0.05 g of platinum water (Pt) and stir evenly. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was applied on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Example 5

Dissolve 5g of ethylene carbonate and 1.23g of lithium bistrifluoromethanesulfonimide (LiTFSI) in 5ml of dimethyl sulfoxide and stir at room temperature to completely dissolve; add 0.08g of platinum water (Pt) and stir evenly. On the Teflon mold, using whatman membrane as the porous supporting framework, the mixture stirred uniformly was applied on both sides of the whatman membrane; the vacuum drying oven was heated at 80°C for 10 hours to cure to form a membrane.

Electrolyte thickness: use a micrometer (accuracy of 0.01 mm) to measure the thickness of the block polymer electrolyte, measure at any 3 points on the membrane, and calculate the average value.

Ionic conductivity: Two stainless steel gaskets are used to clamp the polymer electrolyte, and a 2032 button cell is assembled to measure the impedance according to the formula

Where L is the thickness of the polymer electrolyte, S is the area of the stainless steel gasket, and R is the measured impedance value.

Electrochemical window: The polymer electrolyte is sandwiched between stainless steel and lithium sheet, and a 2032 button cell is assembled. Linear voltammetry measurement is performed. The starting voltage is 2.8V, the maximum potential is 5.5V, and the scanning speed is 1mV S ^-1 .

Examples

Ionic conductivity (S cm ^-1 , 25℃)

Electrochemical window (V)

11	1.4×10 ^-3 1.4×10 ^-3	4.74.7
22	1.13×10 ^-3 1.13×10 ^-3	4.74.7
33	1.51×10 ^-3 1.51×10 ^-3	4.754.75
44	2.01×10 ^-3 2.01×10 ^-3	4.754.75
55	1.18×10 ^-3 1.18×10 ^-3	4.74.7

Preparation of solid-state lithium ion battery: The specific composition of the electrolyte mixture used in the following examples is the same as the corresponding solid polyelectrolyte composition.

Example 6

Grind 80mg of lithium nickel cobalt aluminate and 15mg of conductive agent acetylene black evenly for 40min; add 5mg of binder polyvinylidene fluoride, 3mg of electrolyte mixture and 160μL 1-methyl-2pyrrolidone and evenly grind for 40min; apply to aluminum foil The surface is dried under vacuum at 80°C for 8 hours; the pole piece is cut into R=0.6mm wafers, and the polymer electrolyte in Example 1 is prepared using the above polymer electrolyte to assemble a solid-state lithium ion half-cell, and then lithium metal As a negative electrode.

Example 7

Grind 240mg of lithium iron phosphate and 45mg of conductive agent acetylene black evenly for 40min; add 15mg of binder polyvinylidene fluoride, 15mg of electrolyte mixture and 150μL of 1-methyl-2pyrrolidone to evenly grind for 40min; coat the surface of aluminum foil, Bake at 80°C for 8 hours under vacuum; cut the pole pieces into R=0.6mm wafers and use the above polymer electrolyte to assemble solid lithium ion half-cells. Then use metallic lithium as the negative electrode.

Example 8

Grind 250mg of lithium nickel cobalt aluminate and 46.8mg of conductive agent acetylene black evenly for 40min; add 15mg of binder polyvinylidene fluoride, 15mg of electrolyte mixture and 150μL of 1-methyl-2pyrrolidone for evenly grinding for 40min; coat on The surface of the aluminum foil was dried at 80°C for 8 hours under vacuum conditions; the pole pieces were cut into R=0.6mm wafers, and the solid lithium ion half-cells were assembled using the above polymer electrolyte. Then use metallic lithium as the negative electrode.

Claims

A new type of polycarbonate-based polymer electrolyte, which is characterized by a liquid mixture including a liquid ethylene carbonate, a conductive lithium salt and an organic solvent before crosslinking and curing, to which an initiator or catalyst is added, and a porous support material Immerse in the liquid mixture or apply the liquid mixture to the porous support material, and then solidify to prepare a polymer electrolyte; wherein the composition of each substance in the liquid mixture: ethylene carbonate accounts for the mass fraction of the mixture of 30- 80%, the conductive lithium salt accounts for 10-50% of the mixture, the organic solvent accounts for 1-50% of the mixture, and the initiator or catalyst contains 0.5-5% of ethylene carbonate.
A new polycarbonate-based polymer electrolyte according to claim 1, wherein the structure of ethylene carbonate is as follows:
A new polycarbonate-based polymer electrolyte according to claim 1, wherein the conductive lithium salt is one or more of the following: lithium hexafluorophosphate (LiPF 6 ), lithium perchlorate (LiClO 4 ), Lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bis(trifluoromethanesulfonyl) methyl [LiC(SO 2 CF 3 ) 3 ].
A new polycarbonate-based polymer electrolyte according to claim 1, wherein the organic solvent is one or more of the following: N-methylpyrrolidone (NMP), ethylene carbonate, propylene carbonate , Butylene carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, 1,2-dimethoxyethane, tetraethylenedioxide Alcohol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethyl sulfoxide; the initiator or catalyst is one of the following: dibutyl tin dilaurate, bis(acetylpyruvate) Dibutyltin, azobisisoheptanonitrile (ABVN) azobisisobutyronitrile (AIBN), dimethyl azobisisobutyrate (AIBME), benzoyl peroxide (BPO), platinum water (Pt).
A new polycarbonate-based polymer electrolyte according to claim 1, wherein the porous support material is cellulose nonwoven fabric, polyethylene nonwoven fabric, polypropylene nonwoven fabric, glass fiber nonwoven fabric One or more of cloth and PTFE non-woven fabric.
The method for preparing the novel polycarbonate-based polymer electrolyte according to any one of claims 1 to 5, characterized in that it comprises the steps of: formulating a corresponding mass fraction of ethylene ethylene carbonate, conductive lithium salt and organic solvent Electrolyte, and stir evenly; add initiator or catalyst of corresponding mass fraction and stir well; apply or immerse the above electrolyte into the polytetrafluoroethylene mold containing porous support material, heat and cure at 60-120℃ 2- Film formation in 12 hours.
A polymer solid-state lithium ion battery containing the novel polycarbonate-based polymer electrolyte according to any one of items 1 to 5, characterized in that it includes: a positive electrode, a negative electrode, and a separator and an electrolysis disposed between the positive electrode and the negative electrode Liquid-functional polymer electrolyte.
The polymer solid-state lithium-ion battery according to claim 7, wherein the positive electrode active material is lithium iron phosphate (LiFeO 4 ), lithium nickel cobalt aluminate (NCA), lithium-rich materials (LLOs), lithium cobalt oxide One or more of (LiCoO 2 ), lithium ion lithium fluorophosphate, lithium nickel cobalt manganate, lithium manganese oxide, lithium manganate, lithium nickel manganate, lithium manganese iron phosphate, lithium nickelate (LiNiO 2 ) ; The negative electrode active material is one or more of lithium metal, lithium metal alloy, carbon silicon composite material, lithium titanate, graphite, lithium metal nitride, antimony oxide, carbon germanium composite material, lithium titanium oxide;

The preparation of the positive electrode includes the following steps: (1) The preparation of the positive electrode material includes the following steps: grinding and mixing the positive electrode active material with a mass fraction of 50-90% and the conductive agent acetylene black with a mass fraction of 5-30%, adding Polyvinylidene fluoride (PVDF) with a mass fraction of 1-15%, 1-15% electrolyte mixture and 1-methyl-2pyrrolidone (NMP) are ground and mixed to obtain a positive electrode material, of which 1-methyl-2pyrrolidone (NMP) is used to adjust the viscosity, which is not included in the mass percentage composition of the positive electrode material; (2) The positive electrode material is coated on the surface of the aluminum foil and dried to obtain the positive electrode;

Metal lithium and metal lithium alloy can be directly used as the corresponding negative electrode;

Or the preparation of the negative electrode, including the following steps: (1) Preparation of the negative electrode material: grinding and mixing the negative electrode active material with a mass fraction of 30-80% and the conductive agent acetylene black with a mass fraction of 5-30%; adding the mass fraction Grind and mix 5-25% polyvinylidene fluoride (PVDF), 1-15% electrolyte mixture and 1-methyl-2pyrrolidone (NMP) to obtain negative electrode material; of which 1-methyl-2pyrrolidone (NMP) It is used to adjust the viscosity and is not included in the mass percentage composition of the negative electrode material; (2) coated on the surface of the copper foil and dried to obtain the negative electrode.
The polymer solid-state lithium-ion battery according to claim 8, wherein the composition of the electrolyte mixture in the positive electrode material and the negative electrode material is: the electrolyte mixture liquid component ethylene carbonate accounts for the electrolyte mixture liquid The mass fraction is 30-80%, the conductive lithium salt accounts for 10-50% of the electrolyte mixture, the organic solvent accounts for 1-50% of the electrolyte mixture, and the initiator or catalyst mass fraction is ethylene carbonate 0.5-5% of the mass of ethylene; the specific selection range of each substance in the electrolyte mixture is the same as the selection range of each substance of the polycarbonate-based polymer electrolyte raw material.
The polymer solid-state lithium-ion battery according to claim 7, characterized in that: the preparation of the battery includes the following two methods; (1): ex-situ assembly process-positive electrode, negative electrode and claim 6 Solid polymer electrolyte; (2): In-situ assembly process --- The electrolyte mixture solution of claim 9 is injected into the battery system of positive electrode, separator and negative electrode, and cured at 60-120°C.