KR102536150B1 - Electrode assembly and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a cell including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, an exterior member extending from the separator and formed to surround the outer surface of the cell, and the An electrode assembly including an adhesive portion formed between an outer surface of the separator and an inner surface of an end portion of the exterior member is provided.

Description

Electrode assembly and manufacturing method thereof {ELECTRODE ASSEMBLY AND MANUFACTURING METHOD THEREOF}

The present invention relates to an electrode assembly and a manufacturing method thereof.

As the electronics, communication and space industries develop, the demand for secondary batteries as an energy power source is rapidly increasing. In particular, as the importance of global eco-friendly policies is emphasized, the electric vehicle market is growing rapidly, and research and development on secondary batteries is being actively conducted at home and abroad.

Among various secondary batteries, a lithium secondary battery having a high discharge voltage and energy density is widely used as an energy source for various mobile devices and various electronic products.

A lithium secondary battery may be manufactured by closing a cell structure including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode using an adhesive member, and then storing the battery in a can or pouch.

As a method of finishing the structure of the cell, a method of fixing the rolled or stacked electrode structure by taping the outer surface of the separator has been mainly used.

However, when the lithium secondary battery is used for a long period of time, the adhesive strength of the taping is lowered due to the direct exposure of the taping to the electrolyte. In addition, the lithium secondary battery may generate a high temperature of 100° C. or more when an exothermic phenomenon occurs, and the adhesive strength of the taping is rapidly reduced under such a high temperature condition, resulting in a decrease in stability of the lithium secondary battery. In addition, there is a problem that the capacity of the lithium secondary battery is reduced because the content of the electrolyte solution that can be put into the can or pouch is reduced due to the thickness of the taping.

In particular, when taping is used to finish a lithium secondary battery stored in a pouch, the taping shape protrudes from the outside of the pouch, resulting in a deterioration in the appearance quality of the pouch-type secondary battery.

The present invention provides an electrode assembly that is not exposed to an electrolyte solution, has excellent adhesive properties, and can increase the content of the electrolyte solution by forming an adhesive portion between the outer surface of the separator and the inner surface of the end of the exterior member, and a method for manufacturing the same.

An electrode assembly according to the present invention includes a cell including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, an enclosure extending from the separator, and formed to surround the outer surface of the cell. and an adhesive portion formed between an outer surface of the separation membrane and an inner surface of an end portion of the exterior member.

In one embodiment of the present invention, the electrode assembly may have an adhesive strength of 0.070 N/10 mm or more as measured by the following measurement method.

[measurement method]

1) Specimens were prepared by cutting the separation membrane and the ends of the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.

2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.

3) Measure the 180° adhesive force when the end of the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.

In one embodiment of the present invention, the separator may include a porous substrate and a heat resistant layer formed on at least one surface of the porous substrate.

In one embodiment of the present invention, at least some of the materials included in the adhesive portion and the heat resistance layer may be the same material.

In one embodiment of the present invention, the cells may be formed in a zigzag stack method.

In one embodiment of the present invention, the adhesive part may include a binder and inorganic particles.

In one embodiment of the present invention, the binder is cellulose, polyacrylate, polybenzoate, polyvinylpyrrolidone, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene Fluoride-trichlorethylene, polyacrylonitrile, polystyrene, polymethyl methacrylate, polybutyl acrylate, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate pro Cionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, carboxylmethylcellulose, acrylonitrile styrene butadiene copolymer, polyimide, polyamideimide, polysulfone, poly It may include at least one selected from the group consisting of ether sulfone, styrene butadiene rubber, and polytetrafluoroethylene.

In one embodiment of the present invention, the inorganic particles are aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, barium sulfate, boehmite, aluminum hydroxide, titanium oxide, magnesium oxide, magnesium hydroxide, It may include at least one selected from the group consisting of silica, aluminum nitride, silicon nitride, and boron nitride.

A method for manufacturing an electrode assembly according to the present invention includes (a) providing a separator, (b) manufacturing a cell by alternately stacking a first electrode and a second electrode with the separator interposed therebetween, (c) the After manufacturing the cell, an exterior member extending from the separator covers the outer surface of the cell at least once, and (d) forming an adhesive portion by attaching the outer surface of the separator and the inner surface of an end of the exterior member to each other. do.

In one embodiment of the present invention, the electrode assembly manufactured by the manufacturing method may have an adhesive force of 0.070 N/10 mm or more as measured by the following measuring method.

[measurement method]

1) Specimens were prepared by cutting the separation membrane and the ends of the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.

2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.

3) Measure the 180° adhesive force when the end of the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.

In one embodiment of the present invention, the separator in step (b) may be formed in a zigzag folded form, and the first electrode and the second electrode are alternately inserted and stacked at the folded portion of the separator. it could be

In one embodiment of the present invention, the adhesive part of step (d) applies an adhesive to at least one of the outer surface of the separator and the inner surface of the end of the exterior member, and then the outer surface of the separator and the inner surface of the end of the exterior member are applied. It may be formed by attaching to each other.

In one embodiment of the present invention, the pressure-sensitive adhesive may include a binder and inorganic particles.

In one embodiment of the present invention, the binder is cellulose, polyacrylate, polybenzoate, polyvinylpyrrolidone, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene Fluoride-trichlorethylene, polyacrylonitrile, polystyrene, polymethyl methacrylate, polybutyl acrylate, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate pro Cionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, carboxylmethylcellulose, acrylonitrile styrene butadiene copolymer, polyimide, polyamideimide, polysulfone, poly It may include at least one selected from the group consisting of ether sulfone, styrene butadiene rubber, and polytetrafluoroethylene.

In one embodiment of the present invention, the inorganic particles are aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, barium sulfate, boehmite, aluminum hydroxide, titanium oxide, magnesium oxide, magnesium hydroxide, It may include at least one selected from the group consisting of silica, aluminum nitride, silicon nitride, and boron nitride.

In one embodiment of the present invention, the adhesive part in step (d) applies an organic solvent to at least one of the outer surface of the separator and the inner surface of the end of the exterior member, and then the outer surface of the separator and the inner surface of the end of the exterior member. can be attached to each other.

In one embodiment of the present invention, the organic solvent may include at least one selected from the group consisting of acetone, N-methyl-2-pyrrolidone, methyl ethyl ketone, ethanol, ethyl acetate and isopropyl alcohol. .

In the electrode assembly and method of manufacturing the same according to the present invention, since the adhesive part for finishing the structure of the cell is not exposed to the electrolyte solution, it is possible to prevent the adhesive force from being lowered by the electrolyte solution.

In addition, the electrode assembly and method of manufacturing the same according to the present invention satisfy the adhesive force of a specific numerical range formed between the outer surface of the separator and the inner surface of the end of the exterior member, thereby reducing the adhesive force deterioration even under high temperature conditions, thereby preventing the adhesive part from being detached. By minimizing it, there is an effect of improving the stability of the secondary battery.

In addition, since the electrode assembly and method for manufacturing the same according to the present invention do not have a separate taping for finishing the structure of the cell, the content of the electrolyte solution can be increased by the thickness of the taping, so that the capacity of the secondary battery can be improved.

In addition, the electrode assembly and the method for manufacturing the same according to the present invention do not protrude the taped shape to the outside of the pouch, so that the appearance quality of the pouch-type secondary battery is excellent.

In addition, the electrode assembly and its manufacturing method according to the present invention, when the electrode assembly is wound in a jelly roll form, can form an adhesive portion in a wider area than conventional taping, so that storage and delivery are easy and safe.

1 schematically shows an electrode assembly according to the present invention.
2 schematically shows an electrode assembly according to another embodiment of the present invention.
3 schematically shows a manufacturing process of an electrode assembly according to the present invention.

Structural or functional descriptions of the embodiments disclosed in this specification or application are merely exemplified for the purpose of explaining the embodiments according to the technical spirit of the present invention, and the embodiments according to the technical spirit of the present invention Alternatively, it may be implemented in various forms other than the embodiments disclosed in the application, and the technical spirit of the present invention is not construed as being limited to the embodiments described in this specification or application.

Hereinafter, an electrode assembly and a manufacturing method thereof according to the present invention will be described.

<electrode assembly>

An electrode assembly according to the present invention includes a cell including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, an enclosure extending from the separator, and formed to surround the outer surface of the cell. and an adhesive portion formed between an outer surface of the separation membrane and an inner surface of an end portion of the exterior member.

1 schematically shows an electrode assembly according to the present invention.

Referring to FIG. 1, the electrode assembly 100 according to the present invention includes a first electrode 1, a second electrode 2, and interposed between the first electrode 1 and the second electrode 2 A cell 10 including a separator 3 is included.

The first electrode 1 may be an anode. The cathode may include a cathode current collector and a cathode active material layer formed on the cathode current collector. The positive current collector may include a known conductive material within a range that does not cause a chemical reaction in the secondary battery. For example, the cathode current collector may include any one of stainless steel, nickel (Ni), aluminum (Al), titanium (Ti), copper (Cu), and alloys thereof, and a film (Film), sheet (sheet), foil (foil) can be provided in various forms.

The cathode active material layer may include a cathode active material. The cathode active material may be a material into which lithium (Li) ions can be intercalated and deintercalated. The cathode active material may be lithium metal oxide. For example, the cathode active material may include lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate compound, lithium phosphoric acid It may be one of a manganese-based compound, a lithium cobalt phosphate-based compound, and a lithium vanadium phosphate-based compound, but is not limited thereto.

The second electrode 2 may be a cathode. The negative electrode may include a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The anode current collector may include a known conductive material within a range that does not cause a chemical reaction in the secondary battery. For example, the anode current collector may include any one of stainless steel, nickel (Ni), titanium (Ti), copper (Cu), and surface-treated copper (Cu), and the film ( It may be provided in various forms such as film, sheet, and foil.

The anode active material layer may include an anode active material. The negative electrode active material may be a material into which lithium ions can be intercalated and deintercalated. For example, the anode active material may be any one of carbon-based materials such as crystalline carbon, amorphous carbon, carbon composite, and carbon fiber, lithium alloy, silicon (Si), and tin (Sn). According to embodiments, the negative electrode active material may be natural graphite or artificial graphite, but is not limited thereto.

The first electrode 1 and the second electrode 2 may each include a binder and a conductive material. The binder may improve mechanical stability by mediating a bond between the current collector and the active material layer. For example, the binder may be an organic binder or an aqueous binder. For example, the organic binder is vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, and polymethyl methacrylate. (Polymethylmethancrylate), and the aqueous binder may be styrene-butadiene rubber (SBR), but is not limited thereto. The conductive material may improve electrical conductivity of a secondary battery. The conductive material may include a metal-based material. The conductive material may include a conventional carbon-based conductive material. For example, the conductive material may include any one of graphite, carbon black, graphene, and carbon nanotubes, and preferably include carbon nanotubes.

The cell 10 includes a separator 3 interposed between the first electrode 1 and the second electrode 2 . The separator 3 may be configured to prevent an electrical short between the first electrode 1 and the second electrode 2 and to generate a flow of ions.

The separator 3 may be a porous substrate. The porous substrate may have a thickness of 1 μm to 100 μm, 2 μm to 60 μm, or 5 μm to 30 μm. The pore size (diameter) of the porous substrate may be 0.01 μm to 20 μm, 0.05 μm to 5 μm, or 0.05 μm to 3 μm. The porous substrate may be a porous polymer film or a porous non-woven fabric. The porous polymer film includes an ethylene polymer, a propylene polymer, an ethylene/butene copolymer, an ethylene/hexene copolymer, and an ethylene/methacrylate It may be composed of a single layer or multiple layers including a polyolefin polymer such as a copolymer. The porous nonwoven fabric may include high melting point glass fibers and polyethylene terephthalate fibers. However, it is not limited thereto, and may be a highly heat-resistant separator including ceramic according to an embodiment.

The separator 3 may include the porous substrate and a heat resistant layer formed on at least one surface of the porous substrate. The separator 3 may include a heat resistant layer formed by applying a slurry composition to one or both surfaces of the porous substrate. By including a heat-resistant layer on the porous substrate, heat resistance is excellent and high-temperature dimensional stability may be improved.

The slurry composition may include inorganic particles. The inorganic particles include lumina, boehmite, aluminum hydroxide, titanium oxide, barium titanium oxide, magnesium oxide, and magnesium hydroxide. ), silica, clay, and glass powder.

The slurry composition may include a binder to improve binding force between the inorganic particles. The binder is at least one selected from the group consisting of styrene butyrene rubber, polyacrylamide, polymethacrylate, polyethylacrylate, polyacrylate, polybutylacrylate, sodium polyacrylate, and polyvinylidene fluoride. can include

The cell 10 may be formed in a stacking method. The stacking method can improve energy density compared to prismatic secondary batteries. In addition, the stacking method has excellent durability compared to the winding method in which distortion occurs when charging and discharging are repeated for a long time and the secondary battery swells, and the case space of the secondary battery can be utilized to the maximum.

The cell 10 may be formed in a zigzag stack method. The zigzag stacking method minimizes stress of the cell 10 by stacking the separator 3 in a zigzag manner, and can uniformly stack the first electrode 1 and the second electrode 2 . Due to this, it is possible to significantly reduce the possibility of fire by blocking the possibility of contact between the first electrode 1 and the second electrode 2 .

The electrode assembly 100 according to the present invention extends from the separator 3 and includes an exterior member 20 formed to surround the outer surface of the cell 10 . The exterior member 20 may mean the same as the separation membrane 3 . In FIG. 1 , the exterior member 20 extending from the separator 3 is illustrated as covering the outer surface of the cell 10 once, respectively, but is not limited thereto. If necessary, the exterior member 20 may cover the outer surface of the cell 10 at least once. The first electrode 1, the second electrode 2, and the separator 3 stacked between the cells 10 may be fixed by the exterior member 20.

The electrode assembly 100 according to the present invention includes an adhesive portion 30 formed between the outer surface 3-1 of the separator and the inner surface 20-1 of the end of the exterior member.

An end portion where winding of the exterior member 20 that surrounds the outer surface of the cell 10 is finished may be fixed by the adhesive portion 30 . The outer surface 3-1 of the separation membrane may mean a region corresponding to the inner surface 20-1 of the end of the exterior member. The end of the exterior member 20 may refer to an end of the exterior member 20 extending from the separation membrane 3 . The inner surface 20-1 of the end of the exterior member may mean a region corresponding to the outer surface 3-1 of the separator at the end of the exterior member 20.

1 shows that the adhesive part 30 is formed on both the top and bottom of the cell 10, and FIG. 2 schematically shows an electrode assembly according to another embodiment of the present invention.

Referring to FIG. 2 , it is illustrated that the adhesive portion 30 is formed on one side of the cell 10 . However, the adhesive portion 30 is not limited thereto, and may be formed only on the top or bottom of the cell 10 or on both sides of the cell 10 .

Conventionally, in order to fix the winding end of the separator, a finishing tape is attached to the outer surface of the separator. However, since the finishing tape is directly exposed to the electrolyte, the adhesiveness of the finishing tape is lowered, and the electrolyte content is reduced by the thickness of the finishing tape, thereby reducing the capacity of the secondary battery. In addition, when the electrode assembly is accommodated in a pouch, a finishing tape shape protrudes from the outside of the pouch, resulting in deterioration in the external quality of the secondary battery.

Table 1 below shows the volume of the finishing tape according to the thickness of the finishing tape and the reduction amount of the electrolyte according to the volume of the finishing tape.

finishing tape thickness 50㎛ 150㎛ 300㎛ Finishing tape volume (cc) 0.880 1.690 2.880 Electrolyte reduction ¹⁾ (g) 1.007 1.933 3.295 1) Decreased amount of electrolyte: The density of electrolyte is about 1.144 g/cc.

As can be seen in Table 1, a finishing tape exists on the outer surface of the separator, and as the thickness of the finishing tape increases, the amount of electrolyte solution decreases, and thus the capacity of the secondary battery may decrease.

Therefore, in the present invention, in order to fix the winding end of the exterior member 20, the adhesive portion 30 is provided between the outer surface 3-1 of the separator and the inner surface 20-1 of the end of the exterior member. By being formed, the adhesive portion 30 is not exposed to the electrolyte solution. Accordingly, it is possible to prevent the adhesiveness of the adhesive part 30 from being lowered by the electrolyte, and the capacity of the secondary battery may be improved by increasing the electrolyte content by the thickness of the finishing tape. In addition, since the finishing tape is not used, when the electrode assembly is accommodated in the pouch, it is possible to prevent a deterioration in the quality of the secondary battery due to the protrusion of the finishing tape on the outside of the pouch.

The electrode assembly 100 according to the present invention may have an adhesive force of 0.070 N/10 mm or more as measured by the following measurement method.

[measurement method]

1) Specimens were prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.

2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.

3) Measure the 180° adhesive strength when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.

The adhesive force may be 0.070 N/10 mm or more, 0.071 N/10 mm or more, or 0.092 N/10 mm or more. When the above range is satisfied, it is possible to minimize a shape in which the adhesive portion is detached under an operating temperature condition of the secondary battery of about 30° C. to 60° C.

The electrode assembly 100 according to the present invention may have a high-temperature adhesiveness retention rate measured by the following measurement method, which satisfies Equation 1 below.

[Method for measuring high-temperature adhesive strength retention rate]

1) The adhesive force measured according to the above measurement method is X.

2) The separation membrane and the exterior member having the adhesive portion were cut into 25 mm in width and 25 mm in length to prepare a specimen.

3) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 150° C. and 60% relative humidity for 15 minutes.

3) The 180° adhesive strength when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 150° C. and 60% relative humidity is Y.

[Equation 1]

0.80 < Y/X < 1.00

When Equation 1 is satisfied, the adhesive strength of the adhesive portion is not greatly reduced even under high-temperature conditions of the secondary battery, thereby improving the stability of the secondary battery.

The adhesive portion 30 may be formed from an adhesive composition. The adhesive portion 30 may include a binder and inorganic particles. Adhesive force may be imparted between the outer surface 3-1 of the separation membrane and the inner surface 20-1 of the end portion of the exterior member by the binder, and heat resistance of the adhesive portion 30 may be imparted by the inorganic particles. can

The binder is cellulose, polyacrylate, polybenzoate, polyvinylpyrrolidone, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, poly Acrylonitrile, polystyrene, polymethyl methacrylate, polybutyl acrylate, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, Cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, carboxylmethylcellulose, acrylonitrilestyrenebutadiene copolymer, polyimide, polyamideimide, polysulfone, polyethersulfone, styrene butadiene rubber, and poly It may include one or more selected from the group consisting of tetrafluoroethylene.

The inorganic particles include aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, barium sulfate, boehmite, aluminum hydroxide, titanium oxide, magnesium oxide, magnesium hydroxide, silica, aluminum nitride, silicon nitride and boron nitride. It may include one or more selected from the group consisting of.

At least some of the materials included in the adhesive portion 30 and the heat resistance layer may be the same material. The heat resistance layer may include the binder and the inorganic particles. The binder included in the adhesive portion 30 and the binder included in the heat resistance layer may be made of the same material. The inorganic particles included in the adhesive portion 30 and the inorganic particles included in the heat resistant layer may be made of the same material.

The content of the inorganic particles relative to 100 parts by weight of the pressure-sensitive adhesive composition may be less than 20 parts by weight, less than 18 parts by weight, or less than 15 parts by weight. By satisfying the above range, it is possible to reduce a phenomenon in which the adhesive force of the adhesive portion 30 is lowered under a high temperature condition, thereby minimizing a phenomenon in which the adhesive portion 30 is detached.

<Method of manufacturing electrode assembly>

A method for manufacturing an electrode assembly according to the present invention includes (a) providing a separator, (b) manufacturing a cell by alternately stacking a first electrode and a second electrode with the separator interposed therebetween, (c) the After manufacturing the cell, an exterior member extending from the separator covers the outer surface of the cell at least once, and (d) forming an adhesive portion by attaching the outer surface of the separator and the inner surface of an end of the exterior member to each other. do.

3 schematically shows a manufacturing process of an electrode assembly according to the present invention.

Referring to FIG. 3 , the manufacturing method of the electrode assembly 100 according to the present invention includes (a) providing a separator 3 . The separation membrane 3 may be the same as the above-mentioned separation membrane. The separator 3 is a reel type, and may be unwound and supplied at a constant speed. The separator 3 may have a constant stress in a flattened state by applying a constant tensile force from both sides in the longitudinal direction.

The method of manufacturing the electrode assembly 100 according to the present invention (b) manufacturing the cell 10 by alternately stacking the first electrode 1 and the second electrode 2 with the separator 3 interposed therebetween Include steps. In the step (b), the stacking process may be repeatedly performed to satisfy the predetermined number of electrodes. The first electrode, the second electrode and the cell may be the same as the first electrode, the second electrode and the cell described above.

The separator 3 in step (b) may be formed in a zigzag folded shape, and the first electrode 1 and the second electrode 2 are alternately inserted into the folded portion of the separator 3. It may be layered. The separator 3 in the step (b) may be formed in a zigzag folded form alternately in the left and right directions, and the first electrode 1 and the second electrode 2 are the separator 3 Each time it is folded, it can be alternately inserted from the left or right side and stacked. 2 shows the cell 10 in which the first electrode 1 is stacked first and the second electrode 2 is stacked last, but is not limited thereto, the second electrode 2 is stacked first, and the second electrode 2 is stacked first. 1 electrode 1 may be laminated last.

In the manufacturing method of the electrode assembly 100 according to the present invention, (c) after manufacturing the cell 10, the exterior member 20 extending from the separator 3 covers the outer surface of the cell 10 at least once. It includes a wrapping step. The exterior member 20 may be the same as the aforementioned exterior member. In FIG. 2 , each exterior member 20 extending from the separator 3 is illustrated as covering each side surface of the cell 10 once, but is not limited thereto. For example, one exterior member 20 extending from the separator 3 may cover both sides of the cell 10 once or cover both sides of the cell 10 two or more times.

The manufacturing method of the electrode assembly 100 according to the present invention includes the steps of (d) forming an adhesive portion 30 by attaching the outer surface 3-1 of the separator and the inner surface 20-1 of the end of the exterior member to each other. includes In the step (d), the adhesive part 30 applies an adhesive to at least one of the outer surface 3-1 of the separation membrane and the inner surface 20-1 of the end of the exterior member, and then the outer surface 3-1 of the separation membrane. 1) and the inner surface 20-1 of the end of the exterior member may be formed by attaching each other. The outer surface 3-1 of the separation membrane and the inner surface 20-1 of the end of the exterior member may be the same as the outer surface of the separation membrane and the inner surface of the end of the exterior member.

The separator 3 may be a porous substrate on which the aforementioned heat-resistant layer is not formed. In the step (d), the adhesive may be applied to impart adhesiveness to the separation membrane 3 on which the heat resistance layer is not formed.

The pressure-sensitive adhesive may be formed from a pressure-sensitive adhesive composition. The adhesive may include a binder and inorganic particles. The binder is cellulose, polyacrylate, polybenzoate, polyvinylpyrrolidone, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, poly Acrylonitrile, polystyrene, polymethyl methacrylate, polybutyl acrylate, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, Cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, carboxylmethylcellulose, acrylonitrilestyrenebutadiene copolymer, polyimide, polyamideimide, polysulfone, polyethersulfone, styrene butadiene rubber, and poly It may include one or more selected from the group consisting of tetrafluoroethylene. The inorganic particles include aluminum hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, barium sulfate, boehmite, aluminum hydroxide, titanium oxide, magnesium oxide, magnesium hydroxide, silica, aluminum nitride, silicon nitride and boron nitride. It may include one or more selected from the group consisting of.

The content of the inorganic particles relative to 100 parts by weight of the pressure-sensitive adhesive composition may be less than 20 parts by weight, less than 18 parts by weight, or less than 15 parts by weight. By satisfying the above range, it is possible to reduce a phenomenon in which the adhesive force of the adhesive portion 30 is lowered under a high temperature condition, thereby minimizing a phenomenon in which the adhesive portion 30 is detached.

In the step (d), the adhesive portion 30 applies an organic solvent to at least one of the outer surface 3-1 of the separation membrane and the inner surface 20-1 of the end of the exterior member, and then the outer surface 3 of the separation membrane -1) and the inner surface 20-1 of the end of the exterior member may be formed by attaching each other.

The separator 3 may be a porous substrate on which the aforementioned heat-resistant layer is formed. In the step (d), the organic solvent may be applied to impart adhesiveness to the separation membrane 3 on which the heat resistance layer is formed.

At least some of the materials included in the adhesive portion 30 and the heat resistance layer may be the same material. The heat resistance layer may include the binder and the inorganic particles. The binder included in the adhesive portion 30 and the binder included in the heat resistance layer may be made of the same material. The inorganic particles included in the adhesive portion 30 and the inorganic particles included in the heat resistant layer may be made of the same material.

The organic solvent may include at least one selected from the group consisting of acetone, N-methyl-2-pyrrolidone, methyl ethyl ketone, ethanol, ethyl acetate and isopropyl alcohol.

In the step (d), the efficiency of the manufacturing process of the electrode assembly 100 can be increased by selectively applying an adhesive or an organic solvent according to the structure of the separator 3 to form the adhesive portion 30, and the cell ( 10) has an effect of not requiring a separate taping to finish the structure.

In the manufacturing method of the electrode assembly 100 according to the present invention, the adhesive force measured by the following measuring method may be 0.070 N/10 mm or more.

[measurement method]

1) Specimens were prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.

2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.

3) Measure the 180° adhesive strength when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.

The adhesive force may be 0.070 N/10 mm or more, 0.071 N/10 mm or more, or 0.092 N/10 mm or more. When the above range is satisfied, it is possible to minimize a shape in which the adhesive portion is detached under an operating temperature condition of the secondary battery of about 30° C. to 60° C.

In the measuring method of the electrode assembly 100 according to the present invention, the above-described high-temperature adhesiveness retention rate may satisfy Equation 1 above. When Equation 1 is satisfied, the adhesive strength of the adhesive portion is not greatly reduced even under high-temperature conditions of the secondary battery, thereby improving the stability of the secondary battery.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are only examples for explaining the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

Example

Preparation Example 1

Styrene butyrene rubber (SBR), carboxymethyl cellulose (CMC), and polyvinylidene fluoride (PVDF) as binders are mixed in an acetone solvent in a weight ratio of 5: 1: 4, and then stirred at room temperature for 1 hour to obtain an adhesive composition. manufactured. Thereafter, 5 parts by weight of alumina, which is an inorganic particle, was mixed with 100 parts by weight of the pressure-sensitive adhesive composition, and then stirred in a stirrer for 1 hour to prepare a pressure-sensitive adhesive composition having a solid content of 45%.

Preparation Example 2

Instead of mixing styrene butyrene rubber (SBR), carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) as binders in acetone solvent in a weight ratio of 5:1:4, styrene butyrene rubber as binder in acetone solvent (SBR), carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 5: 1.5: 3.5, but the pressure-sensitive adhesive composition was prepared by the same process as in Preparation Example 1.

Preparation Example 3

By the same process as in Preparation Example 1, except for mixing 8 parts by weight of inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition instead of mixing 5 parts by weight of inorganic particles, Alumina, with respect to 100 parts by weight of the pressure-sensitive adhesive composition. An adhesive composition was prepared.

Production Example 4

Instead of mixing styrene butyrene rubber (SBR), carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) as binders in acetone solvent in a weight ratio of 5:1:4, styrene butyrene rubber (SBR) in acetone solvent ), carboxymethyl cellulose (CMC) and polytetrafluoroethylene (PTFE) were mixed in a weight ratio of 5: 1.5: 3.5, but the pressure-sensitive adhesive composition was prepared by the same process as in Preparation Example 1.

Preparation Example 5

By the same process as in Preparation Example 4, except for mixing 10 parts by weight of inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition instead of mixing 5 parts by weight of alumina as inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition. An adhesive composition was prepared.

Preparation Example 6

By the same process as in Preparation Example 1, except for mixing 20 parts by weight of inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition instead of mixing 5 parts by weight of inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition. An adhesive composition was prepared.

Preparation Example 7

Instead of mixing styrene butyrene rubber (SBR), carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) as binders in acetone solvent in a weight ratio of 5:1:4, styrene butyrene rubber as binder in acetone solvent (SBR), carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 3:1:6, but the pressure-sensitive adhesive composition was prepared by the same process as in Preparation Example 1.

Preparation Example 8

By the same process as in Preparation Example 1, except for mixing 20 parts by weight of inorganic particles with respect to 100 parts by weight of the pressure-sensitive adhesive composition instead of mixing 5 parts by weight of inorganic particles, Alumina, with respect to 100 parts by weight of the pressure-sensitive adhesive composition. An adhesive composition was prepared.

Preparation Example 9

Instead of mixing styrene butyrene rubber (SBR), carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) as binders in acetone solvent in a weight ratio of 5:1:4, styrene butyrene rubber as binder in acetone solvent (SBR), carboxymethyl cellulose (CMC), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 3:1:6, instead of mixing 5 parts by weight of alumina, which is an inorganic particle, with respect to 100 parts by weight of the pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition was prepared by the same process as in Preparation Example 1, except that 20 parts by weight of alumina, which is an inorganic particle, was mixed with 100 parts by weight of the pressure-sensitive adhesive composition.

Preparation Example 10

After applying the pressure-sensitive adhesive composition according to Preparation Example 1 on a PET film having a thickness of 2 μm, it was cured at 50° C. for 72 hours to prepare a pressure-sensitive adhesive sheet having a thickness of 150 μm.

Example 1

Cathode active material LiCoO ₂ , binder polyvinylidene fluoride (PVDF), and conductive material carbon black are mixed in a weight ratio of 92:4:4, and then dispersed in N-methyl-2-pyrrolidone to prepare a cathode slurry did The positive electrode slurry was coated on aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode.

An anode slurry was prepared by mixing a graphite-based active material as an anode active material, styrene-butadiene rubber (SBR) as a binder, and carbon black as a conductive material in a weight ratio of 96:2:2 and then dispersing in water. The negative electrode slurry was coated on a copper foil having a thickness of 15 μm, dried, and rolled to prepare a negative electrode.

While placing the prepared anode on a separator made of polyethylene (PE) having a thickness of 20 μm, the separator was bent by 180°. Thereafter, the separator was bent by 180° while placing the prepared negative electrode on the separator. A cell was manufactured by repeating the process of bending the separator at 180° while placing the positive electrode and the negative electrode on the separator. Then, after wrapping the exterior member extending from the separator once on the outer surface of the cell, using the adhesive composition prepared in Preparation Example 1, the outer surface of the separator and the inner surface of the end of the exterior member are attached to form an electrode assembly with an adhesive portion. was manufactured.

Example 2

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 2 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Example 3

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 3 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Example 4

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 4 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

delete

Example 6

A polymer composition was prepared by mixing styrene butyrene rubber (SBR) and polyvinylidene fluoride (PVDF) as binders in a weight ratio of 6:4 in an acetone solvent and stirring at room temperature for 2 hours. Thereafter, 5 parts by weight of alumina, an inorganic particle, was mixed with 100 parts by weight of the polymer composition, and stirred in a stirrer for 1 hour to prepare a separator composition. Thereafter, the separator composition was slot-coated on both sides of a separator made of polyethylene (PE) having a thickness of 20 μm, respectively, to prepare a separator.

While placing the same anode as in Example 1 on the prepared separator, the separator was bent by 180°. Thereafter, the separator was bent 180° while placing the same negative electrode as in Example 1 on the separator. A cell was manufactured by repeating the process of bending the separator at 180° while placing the positive electrode and the negative electrode on the separator. Then, after wrapping the exterior member extending from the separator once on the outer surface of the cell, N-methyl-2-pyrrolidone was applied to the outer surface of the separator and the inner surface of the end of the exterior member, and after 15 minutes, the An electrode assembly having an adhesive portion was manufactured by attaching the outer surface of the separator and the inner surface of the end of the exterior member.

Example 7

Example 6 except for applying acetone to the outer surface of the separator and the inner surface of the end of the exterior member instead of applying N-methyl-2-pyrrolidone to the outer surface of the separator and the inner surface of the end of the exterior member. An electrode assembly was manufactured by the same process.

Comparative Example 1

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 6 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Comparative Example 2

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 7 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Comparative Example 3

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 8 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Comparative Example 4

An electrode assembly was manufactured by the same process as in Example 1, except that the pressure-sensitive adhesive composition prepared in Preparation Example 9 was used instead of the pressure-sensitive adhesive composition prepared in Preparation Example 1.

Comparative Example 5

Instead of forming an adhesive portion by attaching the outer surface of the separator and the inner surface of the end portion of the exterior member using the pressure-sensitive adhesive composition prepared in Production Example 1, the adhesive sheet prepared in Production Example 10 was applied to the outer surface of the separator and the inner surface of the end portion of the exterior member. An electrode assembly was manufactured by the same process as in Example 1 except for attaching to the outer surface.

Experimental example

Experimental Example 1 - Adhesion evaluation

The adhesive strength and the high-temperature adhesive strength retention rate of the electrode assemblies prepared in Examples 1 to 4, 6, and 7 and Comparative Examples 1 to 5 were measured by the following measurement methods.

-Adhesiveness: When the separation membrane and exterior member with the adhesive part are 25mm in width and length

A specimen was prepared by cutting to a length of 25 mm. Thereafter, after peeling between the adhesive portion and the separation membrane, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes. Then, the 180 ° adhesive force when the exterior member was pulled at a speed of 300 mm / min using a KS B 5521 standard tensile tester at 60 ° C. and 60% relative humidity was measured, and the results are shown in Table 1 below. .

- High-temperature adhesive force retention: The adhesive force measured according to the above measurement method is X.

Apart from the adhesive force measurement method, the same specimen as the specimen used in the adhesive force measurement method was manufactured. Thereafter, after peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 150° C. and 60% relative humidity for 15 minutes. Then, the 180 ° adhesive force Y when the exterior member was pulled at a speed of 300 mm / min using a KS B 5521 standard tensile tester at 150 ° C. and 60% relative humidity was measured, and the ratio of Y to X Calculated and shown in Table 1 below.

Experimental Example 2 - Evaluation of adhesive detachment after electrolyte injection

After accommodating the electrode assemblies prepared in Examples 1 to 4, 6, and 7 and Comparative Examples 1 to 5 in pouches, respectively, electrolyte solutions were injected into the pouches and then sealed to manufacture secondary batteries. Thereafter, the secondary battery was stored in a heating cabinet at 150° C. and 60% relative humidity for 1 week, and then dried at room temperature for 24 hours. Then, after taking out the electrode assemblies prepared in Examples 1 to 4, 6, and 7 and Comparative Examples 1 to 5 from each pouch, the area detached from the adhesive portion compared to the total area of the adhesive portion was calculated and shown in Table 2 below. .

adhesiveness High-temperature adhesion retention rate ¹⁾ Desorption rate of adhesive part ²⁾ Example 1 0.131N/10mm 0.85 10% Example 2 0.133N/10mm 0.85 11% Example 3 0.111N/10mm 0.81 10% Example 4 0.113N/10mm 0.86 10% Example 6 0.077N/10mm 0.93 9% Example 7 0.071N/10mm 0.95 8% Comparative Example 1 0.061N/10mm 0.65 45% Comparative Example 2 0.068N/10mm 0.61 50% Comparative Example 3 0.058N/10mm 0.63 45% Comparative Example 4 0.032N/10mm 0.63 45% Comparative Example 5 - ^{3) -4) -5)} 1) High temperature adhesion retention rate: Y/X
2) Desorption rate of adhesive part (%): Area detached from the adhesive part/total area of the adhesive part × 100
3), 4) -: Not measured
5) -: completely eliminated

As can be seen in Table 2, Examples 1 to 4, 6, and 7 in which the adhesive force measured by the measuring method of the present invention satisfies 0.070 N / 10 mm or more have an adhesive retention rate at high temperature compared to Comparative Examples 1 to 5 It was excellent, and it was confirmed that the rate at which the adhesive portion was detached was reduced. In particular, in Comparative Example 5 in which the adhesive sheet was attached to the outer surface of the separator and the outer surface of the exterior member end as in the prior art, it was confirmed that the adhesive portion was completely detached, and thus the adhesive force at high temperature was significantly reduced.

1: first electrode
2: second electrode
3: separator
10: cell
20: Exterior member
30: adhesive part
100, 200: electrode assembly

Claims (7)

a cell including a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode;
an exterior member extending from the separator and formed to surround an outer surface of the cell; and
An electrode assembly including an adhesive portion formed between the outer surface of the separator and the inner surface of the end of the exterior member,
The adhesive portion is formed from an adhesive composition,
The pressure-sensitive adhesive composition,
styrene butyrene rubber (SBR); carboxymethylcellulose (CMC); And polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE); containing a mixture in a weight ratio of 5: 1 to 1.5: 3 to 3.5,
Including inorganic particles, the content of the inorganic particles relative to 100 parts by weight of the pressure-sensitive adhesive composition is 5 parts by weight to 8 parts by weight,
The electrode assembly has an adhesive strength of 0.111 N / 10 mm to 0.133 N / 10 mm measured by the following measuring method 1, and a high temperature adhesive strength retention rate measured by the following measuring method 2 Satisfies the following formula 1 Electrode assembly:
[Measurement method 1]
1) Specimens were prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.
2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.
3) Measure the 180° adhesive strength when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.
[Measurement method 2]
1) Specimens were prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.
2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 150° C. and 60% relative humidity for 15 minutes.
3) Measure the 180° adhesive force when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 150° C. and 60% relative humidity.
[Equation 1]
0.81 ≤ Y/X ≤ 0.86
The Y is the adhesive force measured by the measuring method 1, and the X is the adhesive force measured by the measuring method 2. delete According to claim 1,
The separator is an electrode assembly comprising a porous substrate and a heat resistance layer formed on at least one surface of the porous substrate. According to claim 3,
An electrode assembly in which at least some of the materials included in the adhesive portion and the heat resistance layer are the same material. (a) providing a separator;
(b) manufacturing a cell by alternately stacking a first electrode and a second electrode with the separator therebetween;
(c) covering the outer surface of the cell with an exterior member extending from the separator at least once after manufacturing the cell; and
(d) a method of manufacturing an electrode assembly comprising the step of attaching the outer surface of the separator and the inner surface of the end of the exterior member to each other to form an adhesive portion,
The adhesive portion is formed from an adhesive composition,
The pressure-sensitive adhesive composition,
styrene butyrene rubber (SBR); carboxymethylcellulose (CMC); And polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE); containing a mixture in a weight ratio of 5: 1 to 1.5: 3 to 3.5,
Including inorganic particles, the content of the inorganic particles relative to 100 parts by weight of the pressure-sensitive adhesive composition is 5 parts by weight to 8 parts by weight,
In the manufacturing method of the electrode assembly, the adhesive force measured by measuring method 1 below is 0.111 N/10mm to 0.133 N/10mm, and the high-temperature adhesive strength retention rate measured by measuring method 2 below satisfies Equation 1 below. method:
[Measurement method 1]
1) A specimen was prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.
2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 60° C. and 60% relative humidity for 3 minutes.
3) Measure the 180° adhesive force when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 60° C. and 60% relative humidity.
[Measurement method 2]
1) A specimen was prepared by cutting the separation membrane and the exterior member having the adhesive portion formed thereon into a horizontal length of 25 mm and a vertical length of 25 mm.
2) After peeling between the adhesive portion and the separator, the adhesive portion was fixed to stainless steel (SUS304 substrate) and maintained at 150° C. and 60% relative humidity for 15 minutes.
3) Measure the 180° adhesive force when the exterior member is pulled at a speed of 300 mm/min using a KS B 5521 standard tensile tester at 150° C. and 60% relative humidity.
[Equation 1]
0.81 ≤ Y/X ≤ 0.86
The Y is the adhesive force measured by the measuring method 1, and the X is the adhesive force measured by the measuring method 2. According to claim 5,
The adhesive part of the step (d) is formed by applying an adhesive to at least one of the outer surface of the separator and the inner surface of the end of the exterior member, and then attaching the outer surface of the separator and the inner surface of the end of the exterior member to each other. manufacturing method.

delete

Images