KR101183010B1 - Can-type decompressed electrochemical device - Google Patents

Abstract

The present invention relates to a can type electrochemical device in which an electrode assembly having a separator interposed between a first electrode, a second electrode, and the positive electrode is accommodated inside a can-type exterior material, wherein the separator has a gel polymer layer on one or both surfaces thereof. It is formed, and provides a can-type electrochemical device characterized in that the inside of the exterior material is subjected to a reduced pressure after assembling the electrochemical device.

Description

Canned electrochemical device under reduced pressure {CAN-TYPE DECOMPRESSED ELECTROCHEMICAL DEVICE}

The present invention relates to a can type electrochemical device in which an electrode assembly having a separator interposed between a first electrode, a second electrode, and the positive electrode is accommodated inside a can-type exterior material, wherein the separator has a gel polymer layer on one or both surfaces thereof. It is formed, and relates to a can-type electrochemical device, characterized in that the inside of the exterior material is subjected to a reduced pressure after assembling the electrochemical device.

Recently, interest in energy storage technology is increasing. As the field of application extends to the energy of mobile phones, camcorders, notebooks and PCs, and even electric vehicles, efforts for research and development of electrochemical devices such as batteries are increasingly materialized. The electrochemical device is one of the most remarkable fields in this respect, and the development of a rechargeable secondary battery has become a focus of attention.

Secondary batteries are chemical cells capable of repeating charging and discharging using reversible interconversion of chemical and electrical energy, and are classified into Ni-MH secondary batteries and lithium secondary batteries.

Most of the bare cells in these secondary batteries are housed in an electrode assembly such as an electrode jelly roll consisting of a positive electrode, a negative electrode and a separator, usually in a can made of steel, aluminum or an aluminum alloy, and closed with a cap assembly to seal the inside of the can. It is formed by injecting and sealing an electrolyte solution into the can.

Such can-type secondary batteries are classified into cylindrical or rectangular batteries in appearance.

1 is an exploded view showing the configuration of a cylindrical secondary battery which is a kind of canned secondary battery. 1 to 1 can also serve as a negative electrode terminal, 2 is a positive electrode, 3 is a negative electrode, 4 is a separator, 5 is a positive lead, 6 is a negative lead, 7 is a positive terminal, 8 is a safety plate, 9 is a PTC element, 10 The silver gasket (GASKET), 11 is an insulating plate, and the positive electrode 2, the separator 4, and the negative electrode 3 are wound and housed in a can-shaped exterior material in the form of a jelly roll. 1, the electrolyte is omitted. 1 relates to a cylindrical secondary battery, wherein the rectangular secondary battery has an essentially similar configuration.

At this time, when using a can made of a thin metal plate, such as stainless steel, nickel plated steel, aluminum or aluminum alloy, the internal pressure of the battery is increased by the gas generated during the charging and discharging process, or jelly due to the repeated charging and discharging of the battery The expansion of the roll caused a problem that the capacity, cycle characteristics, and safety of the battery were lowered. In order to solve this problem, a method of increasing the thickness of an exterior material, such as a can, was used, but when the thickness was artificially increased, it was not possible to satisfy the high capacity of the battery. In addition, if the material of the can is changed to a material of high strength, such as iron or iron alloy, the strength can be increased, but the energy increase per unit weight is not only lowered due to the increase in weight, but also the existing assembly process must be drastically changed. Caused. In fact, in the case of the cylindrical can among the exterior materials, another method other than the above-described material changing method is urgently required since a material having a high strength, such as iron or an iron alloy, is already used.

The present invention is intended to solve the problem that the can-type exterior member deforms due to an increase in pressure or an electrode plate expansion accompanied by gas generation due to an electrochemical reaction during charging and discharging.

The present invention has been found that when a separator coated with one side or both sides with a gel polymer is used, unlike a separator not coated with a gel polymer, vacuum may be applied to the inside of the exterior material, and the present invention is based on this.

The present invention relates to a can type electrochemical device in which an electrode assembly having a separator interposed between a first electrode, a second electrode, and the positive electrode is accommodated inside a can-type exterior material, wherein the separator has a gel polymer layer on one or both surfaces thereof. It is formed, and provides a can-type electrochemical device characterized in that the inside of the exterior material is subjected to a reduced pressure after assembling the electrochemical device.

According to the present invention, an electrochemical device using a membrane coated with one or both sides of a gel polymer, and applying a vacuum to the inside of a can-type exterior material has an internal pressure increase or electrode plate accompanying generation of gas due to side reactions during charging and discharging or at high temperature storage. Swelling due to swelling may deform the exterior material or increase the thickness of the electrochemical device, and the decrease in performance due to the increase in thickness during charge and discharge may be greatly alleviated.

Hereinafter, the present invention will be described in detail.

When a vacuum is applied to a conventional can-type battery, it is difficult to apply a vacuum because the electrolyte is sucked out.

Unlike a separator not coated with a gel polymer, when using a separator coated with one or both sides with a gel polymer as in the present invention, the electrolyte is swelled in the gel polymer layer and the electrolyte is not sucked out even when a vacuum is applied. Vacuum can be applied. Therefore, if a vacuum is applied to the can-type battery according to the present invention, even if gas or the like is generated by side reaction during charging and discharging or at high temperature storage, the increase in thickness does not occur until 1 atm. In addition, it is possible to reduce swelling due to internal pressure increase or electrode plate expansion accompanied with gas generation, to reduce the deformation of the exterior material or to increase the thickness of the electrochemical device, and to significantly alleviate the decrease in performance due to the increase in thickness during charging and discharging. Can be.

The greater the degree of vacuum in the exterior material, the greater the amount of internal gas in the electrochemical device that may cause deformation of the exterior material by internal gas generation. In particular, in the case of the gel polymer having open three-dimensional pores, the electrolyte wettability is improved and the electrolyte retention amount is increased, thereby greatly improving the adhesion strength between the electrode and the separator, thereby increasing the vacuum degree.

In the present invention, the degree of vacuum in the electrochemical device is preferably 1 Torr to 700 Torr. It takes a long time to apply the vacuum to less than 1 Torr, and there is a risk of leakage of some electrolyte, and applying a vacuum above 700 Torr has no effect of applying the vacuum.

In order to increase the degree of vacuum, it is advantageous to make the gel polymer porous structure to minimize the free electrolyte, that is, to absorb the electrolyte as much as possible.

The electrochemical device to which the present invention is applied includes all devices that undergo an electrochemical reaction, and specific examples thereof include all kinds of primary, secondary cells, fuel cells, solar cells, or capacitors. In particular, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery among the secondary batteries is preferable.

The can-type exterior member includes a can body and a cap assembly covering an opening of the can.

When the exterior material of the electrochemical device is a can type, unlike a pouch type, in a can body constituting one of a positive electrode terminal and a negative electrode terminal, a positive electrode coated with a positive electrode active material, a negative electrode coated with a negative electrode active material, and between these two electrodes An electrode assembly including a separator disposed therein is accommodated.

The material of the can-type exterior material may use a metal or alloy material thereof that is commonly used, and their size and shape are not particularly limited. As a non-limiting example, it may be made of iron, aluminum or an aluminum alloy, and in terms of weight reduction, it is preferable to be made of aluminum or an aluminum alloy. Aluminum alloys in which aluminum and manganese, aluminum and nickel, or aluminum and magnesium are mixed may be used to increase the pressure resistance or to resist corrosion of the electrolyte.

The separator prevents internal short circuit due to contact between the positive electrode and the negative electrode, and serves to transmit ions.

According to the present invention, a porous substrate is preferable as a substrate for a separator to which a gel polymer layer is applicable. The porous substrate may be in the form of fibers or membranes, and in the case of fibers, a nonwoven fabric forming a porous web, and may be in the form of spunbond or melt blown composed of long fibers. desirable.

Non-limiting examples of substrate materials that can be used include polyolefin series such as polyethylene (hereinafter referred to as 'PE') or polypropylene (hereinafter referred to as 'PP'), polyethyleneterephthalate, polybutyleneterephthalate , Polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide polyphenyleneoxide, polyphenylenesulfidro, polyethylenenaphthalene, or a mixture thereof, and other heat-resistant engineering plastics can be used without limitation.

The thickness of the substrate is not particularly limited, but is preferably in the range of 1 to 100 μm, more preferably in the range of 5 to 50 μm.

Pore size and porosity of the porous substrate is not particularly limited, porosity is preferably 5 to 95%. The pore size (diameter) is preferably 0.01 to 50 µm, more preferably 0.1 to 20 µm.

The present invention is characterized in that the gel polymer layer is formed on one side or both sides of the separator. The gel polymer layer may be densely coated, but is preferably porous, more preferably a gel polymer layer including a plurality of open three-dimensional pores connected to each other. The average diameter of the open three-dimensional pores is preferably 0.01 to 10㎛.

Gel polymer used in the present invention is a solubility parameter of 15 to 45 MPa ^1/2 in the polymer is preferred. If the solubility is more than 15 MPa ^1/2 and less than 45 MPa ^1/2, it is difficult to be impregnated with (swelling) by a conventional liquid electrolyte for electrochemical device. Therefore, hydrophilic polymers having more polar groups than hydrophobic polymers such as polyolefins are preferable.

The gel polymer may be used as low as possible glass transition temperature (Tg), preferably in the range of -200 to 200 ℃. This is because mechanical properties such as flexibility and elasticity of the final gel polymer layer can be improved.

Non-limiting examples of gel polymers that can be used include PVDF, PVDF copolymers (e.g. polyvinylidene fluoride-co-hexafluoropropylene, PVDF-co-HFP), polyvinylidene Polyvinylidene fluoride-co-trichloroethylene, PVDF-co-CTFE, etc.], carboxy methyl cellulose (CMC) polymer, polyethylene oxide (PEO) polymer, polyacrylonitrile , PAN) polymers, polymethylmethacrylate (PMMA) polymers, or mixtures thereof.

In addition, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer, cellulose acetate, cellulose acetate butyrate, cellulose Cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan , Carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide or mixtures thereof may also be used.

In addition, any material can be used singly or in combination as long as it contains the above-described properties.

The molecular weight of the gel polymer is suitably between 10,000 and 1,000,000. If the molecular weight is too low, it is difficult to form a uniform gel polymer layer during coating. If the molecular weight is too high, the solubility in the solvent decreases and the viscosity becomes too high. There is difficulty.

The thickness of the coating layer of the gel polymer is 0.1 ~ 10㎛ is appropriate, if the thickness of the coating layer is too thin, the adhesive strength with the electrode is insufficient and the electrolyte impregnation ability is poor. In addition, when the thickness is too thick, not only the resistance layer increases in lithium ion migration, but also the thickness of the entire battery becomes thick, which entails a decrease in capacity.

The gel polymer may then gel with the injected electrolyte to form a gel polymer electrolyte.

The gel polymer layer of the present invention may further include inorganic particles and other additives.

According to the present invention, a separator having a gel polymer layer (1) prepares a coating solution by dissolving the gel polymer in a solvent and then forms a dense gel polymer layer by dipping the polyolefin-based separator into the coating solution. Or (2) a gel polymer layer comprising open three-dimensional pores by phase separation into a gel polymer rich phase and a gel polymer deficient phase through nonsolvent addition on a gel polymer solution in which the gel polymer is dissolved in a solvent. Can be formed (see FIG. 3).

Phase separation of the gel polymer rich phase and the gel polymer deficient phase may result in gel polymer deficient phase, which will cause pores in gel polymer solution preparation, gel polymer coating and / or drying to form pores. It can be formed three-dimensionally and connected to each other. As such, the gel polymer layer having the open three-dimensional pore structure connected to each other has a large number of spaces to fill the injected liquid electrolyte, thereby exhibiting high ion conductivity and electrolyte impregnation rate, thereby improving battery performance.

In a first embodiment of the method for producing a gel polymer layer comprising open three-dimensional pores connected to each other on a substrate, a phase-separated solution is applied onto a substrate by adding a part of a nonsolvent to a gel polymer solution in which the gel polymer is dissolved in a solvent. Making a step; And a drying step.

A second embodiment of the method for producing a gel polymer layer comprising open three-dimensional pores connected to each other on a substrate is to apply a phase separation by applying a gel polymer solution in which a gel polymer is dissolved in a solvent onto a substrate and then immersing it in a non-solvent. step; And a drying step.

A third embodiment of a method for producing a gel polymer layer comprising open three-dimensional pores connected to one another on a substrate comprises: applying a gel polymer solution in which the gel polymer is dissolved in a solvent on the substrate; And phase separation by injecting nonsolvent vapor upon drying.

In the method of preparing the gel polymer layer described in the above embodiments, the drying conditions, the type and content of the solvent and the non-solvent may be adjusted to form open three-dimensional pores.

As the solvent for dissolving the gel polymer, it is preferable that the solubility index is similar to that of the gel polymer to be used, and the boiling point is low. This is to facilitate uniform mixing and subsequent solvent removal.

Non-limiting examples of solvents that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone ( N-methyl-2-pyrrolidone, NMP), cyclohexane, or a mixture thereof.

The concentration of the gel polymer in the solvent used is 0.1 to 30%. If the concentration of the polymer is too low, it is difficult to form a uniform gel polymer layer. If the concentration of the polymer is too high, it is difficult to dissolve in the solvent. Increasing viscosity leads to difficulties in the process.

On the other hand, according to one embodiment of the present invention by the phase separation of the solvent / non-solvent phase separated into a gel polymer rich phase and a gel polymer deficient phase, the three-dimensional gel polymer deficient phase is connected to each other In order to form open pores, the choice of solvent and nonsolvent is important. The solvent and nonsolvent selected will depend on the type of gel polymer.

Non-limiting examples of non-solvents for the gel polymer include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol and water.

The ratio of the nonsolvent to the solvent is suitably 0.1 to 50% by volume. If the nonsolvent ratio is too low, phase separation does not occur. If the nonsolvent ratio is too high, precipitation of the polymer occurs, resulting in uneven gel. .

In order to form a gel polymer layer including a plurality of open three-dimensional pores connected to each other, it is preferable to adjust the drying temperature to 50 to 130 degrees. In addition, if the temperature is too low, solvents and non-solvents may remain, which may cause problems in battery performance. If the temperature is over 130 ° C, the membrane fabric may be damaged and the basic characteristics may be changed. For drying times, 5 to 250 seconds are appropriate. If the drying time is short, the performance may decrease due to the remaining solvent / non-solvent, and if it is long, productivity becomes a problem.

The pore size and porosity, pore connection, etc., when the pores are formed from the gel polymer deficient phase can be controlled by the solvent / non-solvent selection / content ratio and the drying temperature / time. In order to increase the size of the pores and increase the connection of the space, it is necessary to lower the drying temperature and increase the drying time to sufficiently grow the phase separated gel polymer deficient phase.

Meanwhile, the method of coating the gel polymer solution or the non-solvent-containing gel polymer solution on the substrate may use a conventional coating method known in the art, for example, dip coating, die coating, or the like. Various methods such as roll coating, comma coating, or a mixture thereof may be used. In addition, during coating, it may be carried out on both sides of the substrate or may be selectively carried out only on one side.

The can-type electrochemical device including a secondary battery uses a separator in which a gel polymer layer is formed, and then, after assembling the electrochemical device, depressurizes the inside of the exterior material, and then, it is a conventional method known in the art, between the positive electrode and the negative electrode. It can be prepared by inserting the separator into the electrode assembly according to a conventional assembly method and then inserting it into the packaging material and adding the electrolyte solution. For example, the can type electrochemical device subjected to the pressure reduction according to the present invention inserts an electrode assembly including a separator, an anode, and a cathode in which a gel polymer layer is formed into the can type exterior material, and then moves to a vacuum chamber to inject the electrolyte solution and apply vacuum. After finishing, it can be manufactured by ball welding.

In this case, the electrode assembly may be wound and formed to insert jelly rolls, but the separator and the electrode may be stacked or inserted into the exterior member by folding or stacking the electrode assembly.

Electrode provided in the electrochemical device according to the present invention can be prepared in the form of the electrode active material bound to the electrode current collector according to a conventional method known in the art, for example, prepared by mixing the electrode active material with a binder After apply | coating one electrode slurry to an electrical power collector, a solvent and a dispersion medium can be removed by drying, etc., binding an active material to an electrical power collector, and binding an active material can be manufactured.

Among the electrode active materials, a cathode active material capable of occluding and releasing lithium may be used. Non-limiting examples thereof include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or the like. And lithium intercalation materials such as composite oxides formed by combination.

As the negative electrode active material, a conventional negative electrode active material capable of absorbing and releasing lithium ions may be used. Non-limiting examples thereof include lithium metal or lithium alloy, carbon, petroleum coke, and activated carbon. , Metal oxides such as TiO ₂ , SnO ₂ , Li ₄ Ti ₅ O _12, and the like, which can repeatedly occlude and release graphite, other carbons or lithium, and metals such as Sn, Si, Al, Pb, and the like.

Non-limiting examples of the positive electrode current collector is a foil made by aluminum, nickel or a combination thereof, and non-limiting examples of the negative electrode current collector by copper, gold, nickel or copper alloy or a combination thereof Foils produced.

Electrolyte that may be used in the present invention is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, contain an alkali metal cation or an ion composed of a combination thereof, such as K ^+, and B ^- is PF _{^{6 -, BF 4 -, Cl}} -, Br -, I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 Salts containing ions consisting of anions such as SO ₂ ) ₃ ^- or a combination thereof are propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC ), Dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethylcarbonate (EMC), gamma butyrolactone (GBL) or these Some are dissolved or dissociated in an organic solvent consisting of a mixture of, but are not limited thereto.

The electrolyte injection may be performed at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and the required physical properties of the final product. That is, it may be applied before the battery assembly or at the end of battery assembly.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

[Example]

Example  One

1-1. Membrane manufacturer

A polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVdF-CTFE) polymer was added to acetone in about 5% by weight, and then dissolved at a temperature of 50 ° C. for about 12 hours or more to prepare a polymer solution. Non-solvent methanol was added to this polymer solution at 30% by volume on acetone basis. The solution thus prepared was coated on Tonen's F12BMS separator porous substrate (porosity 50%) having a thickness of about 12 μm by dip coating, and the coating thickness was adjusted to about 2 μm. As measured by the air permeability measuring device, the air permeability of the F12BMS fabric was about 240 ~ 260 seconds, and the air permeability was about 350 ~ 400 seconds when the coated gel polymer layer was included. It was confirmed that the separator of Example 1 prepared according to the present invention had a gel polymer layer including a plurality of open three-dimensional pores connected to each other on a substrate (see FIG. 4).

1-2. Lithium secondary battery manufacturing

(Anode manufacture)

92 wt% of LiCoO ₂ as a positive electrode active material, 4 wt% of carbon black as a conductive material, and 4 wt% of polyvinylidene fluoride (PVdF) as a binder were added to N-methyl-2 pyrrolidone (NMP) as a solvent. Addition to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was coated and dried on an aluminum thin film having a thickness of about 20 μm, which is a positive electrode current collector, to prepare a positive electrode, and then roll press was performed.

(Cathode production)

A negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive material at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent. The negative electrode mixture slurry was coated and dried on a copper thin film having a thickness of 10 μm, which is a negative electrode current collector, to prepare a negative electrode, and then roll press was performed.

(Battery manufacturing)

The positive electrode, the negative electrode, and the separator prepared in Example 1-1 were stacked and inserted into the can-type exterior material in the form of a jelly roll, and ethylene carbonate / ethylmethyl in which 1 M lithium hexafluorophosphate (LiPF ₆ ) was dissolved. A lithium secondary battery was prepared by injecting a carbonate (EC / EMC = 1: 2, volume ratio) -based electrolyte.

After the electrolyte solution was injected into the vacuum chamber, the pressure was reduced to 50 Torr, and the ball inlet was sealed by proceeding with ball welding.

Comparative example  One

A lithium secondary battery was manufactured in the same manner as in Example 1, except that ball welding was performed under normal pressure without sealing under vacuum.

Experimental Example  1. Performance Evaluation of Lithium Secondary Battery (Room Temperature Life Characteristics)

The 423450 square lithium secondary battery manufactured by the method of Example 1 and Comparative Example 1 was repeatedly charged and discharged 400 cycles in a section of 4.2 to 3V at a current of 1C at a temperature of 23 ° C. 5 shows the life characteristics and the tendency to increase the thickness during the cycles of the square batteries manufactured by the method of Example 1 and Comparative Example 1. As shown in FIG. 5, the 400 cycle characteristics of the battery subjected to vacuum decompression were improved by about 7% compared to Comparative Example 1 which was not decompressed, and in particular, the thickness increase was improved by about 200 μm after 400 charge / discharge cycles.

1 is a view showing the configuration of a cylindrical nonaqueous electrolyte battery which is a kind of can type battery.

2 is a schematic diagram illustrating a separator having a gel polymer layer used in the present invention.

Figure 3 shows a basic ternary phase diagram of a phase separation method for forming a gel polymer layer comprising open three-dimensional pores.

4 is a scanning electron micrograph of a gel polymer layer having an open-porous structure formed in Example 1. FIG.

5 is a graph comparing the lifespan characteristics and thickness increase of 400 times of the square batteries manufactured in Example 1 and Comparative Example 1. FIG.

Claims (12)

In a can type electrochemical device in which an electrode assembly having a separator interposed between a first electrode, a second electrode, and the positive electrode is accommodated inside a can-type exterior material, the separator has a gel polymer layer formed on one side or both sides thereof. , Can-type electrochemical device, characterized in that the inside of the packaging material after the decompression treatment after assembling the electrochemical device. The can type electrochemical device according to claim 1, wherein the vacuum degree in the electrochemical device is 1 to 700 Torr. The can type electrochemical device according to claim 1, wherein the decompression treatment is performed after injecting an electrolyte solution. The can-type electrochemical device of claim 1, wherein the can-type exterior member has a can body; and a cap assembly covering an opening of the can. The can type electrochemical device according to claim 1, which is a lithium secondary battery. The can-type electrochemical device of claim 1, wherein the separator has a gel polymer layer including a plurality of open three-dimensional pores connected to each other on a substrate. The gel polymer layer according to claim 6, wherein the gel polymer layer comprising open three-dimensional pores is added to the gel polymer rich phase and the gel polymer deficient phase through nonsolvent addition on the gel polymer solution in which the gel polymer is dissolved in a solvent. Can-type electrochemical device, characterized in that formed by phase separation. The method of claim 6, wherein the non-solvent is added to the gel polymer solution in which the gel polymer is dissolved in a solvent, and then applied onto the substrate in a phase-separated state. After applying the gel polymer solution in which the gel polymer is dissolved in a solvent on a substrate, it is immersed in a non-solvent to cause phase separation, By applying a gel polymer solution in which the gel polymer is dissolved in a solvent on a substrate, and then phase separation by spraying a non-solvent vapor upon drying, A can type electrochemical device, characterized in that open three-dimensional pores are formed in a gel polymer layer. The method of claim 1, wherein the gel polymer is a can type electrochemical device characterized by a solubility index of 15 to 45 MPa ^1/2. The can-type electrochemical device according to claim 1, wherein the gel polymer has a molecular weight of 10,000 to 1,000,000. The can type electrochemical device according to claim 6, wherein the average diameter of the pores is 0.01 to 10 µm. The can-type electrochemical device according to claim 1, wherein the separator substrate has a thickness of 1 to 100 µm and a gel polymer layer of 0.1 to 10 µm.

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