Apparatus and method for manufacturing secondary battery, and secondary battery manufactured thereby

Abstract

The present invention relates to a secondary battery manufacturing apparatus comprising a winding unit that receives and winds an electrode and a separator, wherein the winding unit comprises a core on which a sheet-shaped electrode and a separator are wound; a heating unit that supplies heat to the core; and a hot air supply unit that supplies heated air to the core.

Description

Technology Field

[0001] The present invention relates to a secondary battery manufacturing apparatus, a manufacturing method, and a secondary battery. Specifically, the present invention relates to a secondary battery manufacturing apparatus, a manufacturing method, and a secondary battery that maintains a constant temperature of a core on which a battery assembly is wound and the surrounding environment. Background Technology

[0002] Secondary batteries are classified according to the shape of the battery case into cylindrical and prismatic batteries, in which the battery assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries, in which the battery assembly is housed in a pouch-type case made of aluminum laminate sheets.

[0003] Methods for manufacturing a battery assembly include a jelly roll type (winding type) in which a separator is laminated between the negative electrode and the positive electrode and then wound; a stacking type in which the negative electrode and the positive electrode are cut to have the required width and length, and then the negative electrode, separator, and positive electrode are laminated repeatedly; and a stack-and-folding type in which unit cells are placed side by side on a folding separator and then folded from one side.

[0004] Among these, the jellyroll-type battery assembly is manufactured so that the positive electrode, separator, and negative electrode are wound together in the core.

[0005] In conventional battery assembly manufacturing methods, the separator is pre-winded before the positive and negative electrodes are wound; however, since the pre-winded separator is not fixed to the winding core, a problem occurred where the separator folded when the positive and negative electrodes were wound.

[0006] Figure 1 is a cross-sectional view illustrating a part of a conventional battery assembly. Since the length of the positive electrode in a conventional battery assembly is shorter than that of the negative electrode, the capacity of the manufactured battery assembly is proportional to the length of the positive electrode, and more specifically, proportional to the area where the positive active material is applied on the surface of the positive current collector at the positive electrode. Therefore, it is advantageous in terms of capacity to apply the positive active material as widely as possible on the surface of the positive current collector, but when heat is concentrated in the center of the battery assembly, the separator at the beginning of the positive electrode undergoes thermal shrinkage, causing a short circuit due to contact between the positive electrode and the negative electrode.

[0007] Therefore, there is a growing need for secondary battery manufacturing equipment and secondary batteries that can fundamentally resolve these issues and improve problems such as separator folding and short circuits. Prior art literature

[0008] Korean Registered Patent No. 10-2019-0118135 The problem to be solved

[0009] Based on the problems of the aforementioned prior art, the present invention aims to provide a secondary battery manufacturing apparatus and a manufacturing method that maintain a constant temperature of the core around which a battery assembly is wound and the temperature of the core.

[0010] Furthermore, the present invention aims to provide a secondary battery that prevents a short circuit from occurring inside the battery assembly due to stress concentration at the end of the positive electrode, which damages the separator. means of solving the problem

[0011] One embodiment of the present invention provides a secondary battery manufacturing apparatus comprising a winding unit that receives and winds an electrode and a separator, wherein the winding unit comprises a core on which a sheet-shaped electrode and a separator are wound; a heating unit that supplies heat to the core; and a hot air supply unit that supplies heated air to the core.

[0012] In another embodiment of the present invention, a method for manufacturing a secondary battery manufactured by the secondary battery manufacturing apparatus comprises the steps of heating a winding core and introducing a sheet-shaped electrode and a separator into the winding core.

[0013] In another embodiment of the present invention, a secondary battery is provided comprising a can that accommodates a battery assembly in which a sheet-shaped electrode and a separator are wound, wherein the battery assembly has a pre-wound separator positioned at the center and the electrode and the separator are wound thereon. Effects of the invention

[0014] The secondary battery manufacturing apparatus and manufacturing method according to an embodiment of the present invention can maintain a constant temperature of the winding core and the surrounding area of ​​the winding core where the battery assembly is wound, thereby facilitating the adhesion of the separator and the winding of the battery assembly.

[0015] In addition, the secondary battery according to the present invention can prevent an internal short circuit from occurring due to damage to the separator caused by the positive terminal. Brief explanation of the drawing

[0016] Figure 1 is a cross-sectional view illustrating a part of a conventional battery assembly. FIG. 2 is a cross-sectional view illustrating a secondary battery manufacturing apparatus according to one embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a winding section according to one embodiment of the present invention. FIG. 4(a) is a cross-sectional view illustrating a battery assembly having a positive electrode, a separator, a negative electrode, and an auxiliary separator stacked according to one embodiment of the present invention, and FIG. 4(b) is a cross-sectional view illustrating a wound battery assembly according to one embodiment of the present invention. Specific details for implementing the invention

[0017] The present invention will be described in detail below with reference to the drawings. However, the drawings are intended to illustrate the invention, and the scope of the invention is not limited by the drawings.

[0019] FIG. 2 is a cross-sectional view illustrating a secondary battery manufacturing apparatus (100) according to one embodiment of the present invention.

[0020] The secondary battery manufacturing device (100) may include a first sheet supply unit (110), a second sheet supply unit (120), and a winding unit (130).

[0021] The secondary battery manufacturing device (100) may include first and second sheet supply units (110, 120) that supply electrodes and separators to a winding unit (130). For example, the first sheet supply unit (110) may supply a first sheet, on which a positive electrode is laminated on one side of a separator, to the winding unit (130). And, the second sheet supply unit (120) may supply a second sheet, on which a negative electrode is laminated on one side of a separator, to the winding unit (130). Accordingly, the winding unit (130) may be wound in the order of negative electrode, separator, positive electrode, and separator, or in the order of positive electrode, separator, negative electrode, and separator. That is, the battery assembly may include two separators, a positive electrode, and a negative electrode.

[0022] FIG. 3 is a cross-sectional view illustrating a winding section (130) according to one embodiment of the present invention. The winding section (130) may include a winding core (131), a heating section (132), and a hot air supply section (133).

[0023] The core (131) can manufacture a battery assembly by stacking and winding a sheet-shaped positive electrode, a separator, and a negative electrode.

[0024] The core (131) may be provided in a cylindrical or rod shape and can wind the positive electrode, separator, and negative electrode through rotational movement. Accordingly, the core (131) may be equipped with a motor (M) at one end. The motor provides power to the core (131), and the core (131) can rotate using the power provided by the motor.

[0025] In one embodiment, the core (131) may be provided with a cross-sectional shape perpendicular to the axis of rotation in a circular or ring shape. The core (131) may be provided with a groove in which a separator is fixed at an opposing position.

[0026] In another embodiment, the core (131) may consist of two semicircular or semicircular cores joined at a certain distance apart.

[0027] The secondary battery manufacturing device (100) according to the present invention can fix two separators in a groove provided at the outermost edge of the winding core (131) or in a gap spaced apart between two winding cores (131) and rotate the winding core (131) to wind the positive electrode, separator, and negative electrode.

[0028] At this time, an adhesive material may be applied to the portion of the separator where the positive and negative electrodes are not laminated. That is, the secondary battery manufacturing device (100) according to the present invention may further include an adhesive supply unit (not shown) that supplies and applies an adhesive to the front end of the separator. Here, the front end of the separator may refer to the portion that is coupled to the winding core (131).

[0029] In the secondary battery manufacturing apparatus (100) according to the present invention, a first sheet and a second sheet are provided on a winding core (131), and a separator included in either the first sheet or the second sheet is fixed to the winding core (131), and then the separator with an adhesive applied thereto can be pre-winded onto the winding core (131) by the rotation of the winding core (131). Then, a separator (or the first sheet and the second sheet) having a negative electrode and a positive electrode stacked thereon is wound, and a jelly-roll type battery assembly can be manufactured.

[0030] Alternatively, an adhesive supply unit may be positioned at the front end of the winding unit (130) to supply and apply adhesive to at least one surface of the separator that is pre-winded on the winding core (131). In other words, the secondary battery manufacturing device (100) according to the present invention may further include a third sheet supply unit (not shown) that supplies a pre-winding separator (not shown) that is pre-winded before the first and second sheets are wound on the winding core (131). And, an adhesive may be applied to one surface of the pre-winding separator by the adhesive supply unit before it is wound on the winding core (131).

[0031] The secondary battery manufacturing device (100) according to the present invention can fix an electrode laminate to the pre-winded separator by pre-winding the separator coated with adhesive before the negative electrode, separator, and positive electrode are supplied to the winding core (131) and wound.

[0032] The secondary battery manufacturing device (100) according to the present invention can prevent the electrode stack from being pushed and folded as the electrode stack is wound multiple times on the winding core (131) by having an adhesive force on the separator that is wound on the winding core (131). At this time, the electrode stack may refer to a form in which a negative electrode, a separator, and a positive electrode are wound in order.

[0034] The heating unit (132) can supply heat to the core (131). The heating unit (132) can be provided along the longitudinal direction of the core (131). Accordingly, the heating unit (132) can supply heat to the front surface of the core (131) to maintain a constant temperature on the front surface of the core (131).

[0035] In one embodiment, the core (131) is in the shape of a column with a circular cross-sectional shape perpendicular to the rotation axis, and the heating part (132) may be provided on the outer surface.

[0036] In another embodiment, the core (131) may be a column with a ring-shaped cross-sectional shape perpendicular to the rotation axis, and the heating part (132) may be located inside the core (131). In this case, the heating part (132) may be provided in contact with the inner surface of the core (131) or provided at a certain distance from the inner surface of the core (131).

[0037] The heating unit (132) is not specifically limited to any device that supplies heat to the front of the coil core (131), but may include, for example, a heating wire, a PTC heater, a heater pipe, etc.

[0038] The heating unit (132) can heat the temperature of the coil core (131) to a temperature within the range of 50°C to 100°C. Preferably, the coil core (131) can be heated to a temperature within the range of 60°C to 100°C, and more preferably, 70°C to 100°C.

[0039] The heating unit (132) can facilitate the attachment of the separator with the adhesive applied to the core (131). That is, the heating unit (132) can increase the adhesive strength by heating the adhesive applied to one side of the separator.

[0040] Therefore, if the temperature of the core (131) is less than 50℃, the adhesive strength of the adhesive applied to the separator decreases, so when the separator is wound on the core (131), the separator is not fixed to the core (131) and may fold.

[0041] And, if the temperature of the coil core (131) exceeds 100℃, the effect of increasing the adhesive strength of the adhesive is negligible compared to the energy supplied to heat the coil core (131).

[0043] The hot air supply unit (133) can supply heated air to the core (131) or to the battery assembly wound on the core (131). The hot air supply unit (133) can maintain a constant temperature around the winding unit and a constant temperature of the battery assembly wound on the winding unit. In other words, the hot air supply unit (133) can maintain a constant process temperature of the process in which the battery assembly is wound on the core (131).

[0044] Therefore, the hot air supply unit (133) can maintain the adhesive force of the separator film wound on the core (131).

[0045] The hot air supply unit (133) can supply hot air within a temperature range of 30°C to 70°C. Preferably, it can supply air heated to a temperature within a range of 40°C to 60°C.

[0046] If the temperature of the hot air supplied by the hot air supply unit (133) is less than 30℃, the heat is not transferred to the inside of the battery assembly wound on the core (131), so the adhesive strength of the separator wound on the core (131) is reduced, or a temperature difference occurs between the inside and outside of the battery assembly, which may cause a problem in which the quality of the secondary battery, which is the final product, is degraded.

[0047] And, if the temperature of the hot air supplied by the hot air supply unit (133) exceeds 70℃, the increase in effects such as increased adhesion of the pre-wound separator and increased quality of the secondary battery is minimal compared to the energy supplied to maintain the temperature around the winding unit and the temperature of the battery assembly.

[0049] The secondary battery manufacturing device (100) according to the present invention may further include an auxiliary separator supply unit (not shown).

[0050] When the secondary battery manufacturing device (100) winds the positive electrode, separator, and negative electrode onto the core (131) to prevent internal short circuits, the positive electrode is introduced later than the negative electrode, so that a gap may occur between the winding start point of the positive electrode and the winding start point of the negative electrode.

[0051] Accordingly, in order to prevent the separator from being damaged by the positive end as the battery assembly is wound onto the winding core (131), the auxiliary separator supply unit can supply an auxiliary separator to one side of the negative electrode corresponding to the positive end. In other words, the auxiliary separator supply unit can supply an auxiliary separator in the form of a sheet, and can supply the auxiliary separator such that at least a portion of one side of the auxiliary separator is located in an area facing the positive end.

[0052] The end portion of the positive electrode may refer to the end portion where the positive electrode is first wound onto the core (110). That is, the auxiliary separator supply unit may supply the auxiliary separator to the beginning portion of the negative electrode's winding, and the auxiliary separator may be positioned between the negative electrode and the separator. Here, one side of the negative electrode may refer to the side of the negative electrode facing the separator.

[0054] The secondary battery manufacturing device (100) according to the present invention may further include a temperature measuring unit (not shown) for measuring the temperature of the winding core (131).

[0055] The temperature measuring unit may be positioned in contact with either the inner or outer surface of the coil core (131), or positioned in close proximity to either the inner or outer surface of the coil core (131).

[0056] Additionally, the temperature measuring unit can measure the process temperature when the battery assembly is wound onto the winding core (131). For example, the temperature measuring unit may be located on the opposite side of the end of the winding core (131) that is connected to the motor.

[0057] The secondary battery manufacturing device (100) according to the present invention may further include a control unit (not shown) that controls a heating unit (132) and a hot air supply unit (133) by measuring the temperature around the core (131) and the winding unit measured by the temperature measuring unit.

[0058] That is, the secondary battery manufacturing device (100) according to the present invention can maintain a constant ambient temperature of the winding core (131) and the winding part, thereby facilitating the adhesion of the separator to the winding core (131).

[0060] The method for manufacturing a secondary battery according to the present invention may include a step of heating a core (S10), a step of supplying hot air to the core (S20), and a step of sequentially introducing a sheet-shaped electrode and a separator into the core (S30).

[0061] In addition, the method for manufacturing a secondary battery according to the present invention may further include the step (S40) of winding a separator onto a core.

[0062] The step of heating the core (S10) and the step of supplying hot air to the core (S20) can form an adhesive force on the pre-wound separator in the step of winding the separator onto the core (S30).

[0063] The separator that is wound may have an adhesive applied to one side, or an adhesive layer containing an adhesive or adhesive force may be laminated.

[0064] In addition, the separator wound on the core has adhesive strength only during the process, and for example, the separator / adhesive material may have an adhesive strength of 20.2 gf / 20 mm or more, preferably 21 gf / 20 mm or more, as measured by a 90° peel test.

[0065] In the step (S40) of winding a separator onto a core, the pre-wound separator includes an adhesive or an adhesive layer on one side, and the adhesive or the adhesive layer may have adhesive strength due to heat.

[0066] Accordingly, the step of heating the core (S10) and the step of supplying hot air to the core (S20) may heat the core or provide hot air to the core on which the separator is pre-wound. At this time, the core may be heated to 50°C to 100°C, or hot air of 30°C to 70°C may be provided to the core on which the separator is pre-wound.

[0067] If the temperature of the core and the surrounding area is below the above temperature range, a problem may occur in which adhesion is not generated to the pre-wound separator. Furthermore, if the temperature of the core and the surrounding area exceeds the above temperature range, the increase in adhesion force that allows the separator to fix the electrode laminate may be negligible compared to the energy supplied to heat the core and the surrounding area.

[0068] The step (S30) of sequentially inserting sheet-shaped electrodes and separators into the core can be performed by fixing a portion of the cathode, separator, and anode to one side of the pre-wound separator, and then rotating the core to wind the electrode laminate.

[0069] Alternatively, the step (S30) of sequentially introducing a sheet-shaped cathode, a separator, and an anode into the core may be performed by manufacturing an electrode laminate formed by sequentially stacking a plurality of cathodes, separators, and anodes, fixing a part of the electrode laminate to one side of a pre-wound separator, and then rotating the core to wind the electrode laminate.

[0070] The method for manufacturing a secondary battery according to the present invention may further include the step (S50) of supplying an auxiliary separator.

[0071] The step of supplying the auxiliary separator (S50) may position the auxiliary separator between the cathode and the separator. Additionally, the step of supplying the auxiliary separator (S50) may include a step of laminating the auxiliary separator at the starting region where the winding of the anode begins, that is, at the end of the anode where the winding of the anode begins. Accordingly, at least a portion of one side of the auxiliary separator may be supplied to a region corresponding to the end of the starting point of the anode winding.

[0072] The auxiliary separator can acquire adhesive properties by receiving heat from a heated core or hot air supplied to the core. In other words, the auxiliary separator acquires adhesive properties only during the process and can have the same adhesive properties as the separator pre-wound on the core.

[0074] A secondary battery (not shown) according to the present invention may include a can (not shown), a battery assembly (10), and a cap assembly (not shown).

[0075] The can may be provided with a cylindrical structure having a space formed inside. The can may accommodate a battery assembly (10) including an electrode and a separator and an electrolyte (not shown) in the internal space. One side of the can may have an open structure, and the other side may have a sealed structure. Here, the one side and the other side of the can refer to ends located at the top and bottom along the direction of gravity or the central axis of the can (11).

[0076] On one side of the open can, a beading portion (not shown) folded toward the center of the secondary battery may be provided. Additionally, the can may be provided with a crimping portion (not shown) above the beading portion. That is, the crimping portion may be located at the uppermost side of the can.

[0077] The can can be made of a lightweight conductive metal material such as aluminum or aluminum alloy.

[0079] FIG. 4(a) is a cross-sectional view illustrating a battery assembly (10) in which a positive electrode (1), a separator (2), a negative electrode (3), and an auxiliary separator (4) are stacked according to one embodiment of the present invention, and FIG. 4(b) is a cross-sectional view illustrating a wound battery assembly (10) according to one embodiment of the present invention.

[0080] The battery assembly (10) is a power generation device capable of charging and discharging, having a structure in which electrodes (1, 3) and a separator (2) are laminated and then wound. In this case, the electrodes (1, 3) may include a positive electrode (1) and a negative electrode (3). It may include a jelly-roll type structure in which a separator (2) is interposed on one side of each of the long sheet-type positive electrode (1) and negative electrode (3) coated with an active material and wound. Here, one side may refer to one of the widest areas of the positive electrode (1) and the negative electrode (2).

[0081] A separator (2) may be positioned at the center of the battery assembly (10), between the positive electrode (1) and the negative electrode (3), and at the outermost part of the battery assembly (10).

[0082] For example, it may be wound in the order of separator (2), negative electrode (3), separator (2), positive electrode (1), and separator (2) from the center of the battery assembly (10), or in the order of separator (2), positive electrode (1), separator (2), negative electrode (3), and separator (2).

[0083] Additionally, the separator (2) located at the center of the battery assembly (10) may have adhesive properties. The separator (2) having adhesive properties may increase the fixing force between the battery assembly (10) and the winding core (110), making it easier for the battery assembly (10) to be wound onto the winding core (110). The separator (2) located at the center of the battery assembly (10) may have adhesive properties on the separator (2) itself, or an adhesive layer (not shown) may be laminated onto a substrate. The separator (2) located at the center of the battery assembly (10) may have adhesive properties only during the process, for example, the separator (2) or the adhesive layer may have adhesive properties of 20.2 gf / 20 mm or more, preferably 21 gf / 20 mm or more, as measured by a 90° peel test.

[0084] The battery assembly (10) according to the present invention may further include an auxiliary separator (4). As the battery assembly (10) expands due to charging and discharging, stress is concentrated at the end of the positive electrode (1), and the separator (2) may be damaged by the end of the positive electrode (1). The auxiliary separator (4) can prevent the end of the positive electrode (1) from damaging the separator and coming into contact with the negative electrode (3).

[0086] A cap assembly (not shown) is coupled to an open portion of the can and may include a top cap (not shown), a safety vent (not shown), and a current interrupt device (CID) (not shown).

[0087] The top cap can serve as a terminal for external electrical connection. The safety vent can discharge high-pressure gas if gas accumulates inside above a certain level due to an increase in internal pressure, and the current cutoff element can cut off the current when the battery's internal pressure rises.

[0089] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0090] 1: Positive electrode 2: Separator 3: Cathode 4: Auxiliary separator 10: Battery assembly 100: Secondary battery manufacturing device 110: 1st Sheet Supply Unit 120: Second sheet supply unit 130: Winding section 131: Power 132: Heating part 133: Hot air provider

Claims

Claim 1 A secondary battery manufacturing apparatus comprising a winding unit that receives and winds an electrode and a separator, wherein the winding unit comprises a core on which a sheet-shaped electrode and a separator are wound; a heating unit that supplies heat to the core and a hot air supply unit that supplies heated air to the core, wherein the heating unit heats the temperature of the core to a temperature within the range of 50°C to 100°C and the hot air supply unit supplies air heated to a temperature within the range of 30°C to 70°C. Claim 2 delete Claim 3 delete Claim 4 A secondary battery manufacturing apparatus according to claim 1, further comprising a temperature measuring unit for measuring the temperature of the winding core. Claim 5 A secondary battery manufacturing apparatus according to claim 1, further comprising an auxiliary separator supply unit that supplies a sheet-shaped auxiliary separator between the electrode and the separator when the electrode and the separator are wound. Claim 6 A secondary battery manufacturing apparatus according to claim 5, wherein the auxiliary separator supply unit supplies the auxiliary separator such that at least a portion of one surface of the auxiliary separator is positioned at the end of the electrode. Claim 7 A method for manufacturing a secondary battery manufactured by a secondary battery manufacturing apparatus according to any one of claims 1, 4 to 6, comprising: a step in which a heating unit heats a winding core; a step in which a hot air supply unit supplies hot air to the winding core; and a step in which a sheet-shaped electrode and a separator are wound on the winding core, wherein the heating unit heats the temperature of the winding core to a temperature within the range of 50℃ to 100℃, and the hot air supply unit supplies air heated to a temperature within the range of 30℃ to 70℃. Claim 8 A method for manufacturing a secondary battery according to claim 7, further comprising the step of pre-winding a separator onto the core, wherein the step of heating the core forms an adhesive force on the pre-winded separator. Claim 9 A method for manufacturing a secondary battery according to claim 7, comprising the step of winding an auxiliary separator between the electrode and the separator and at a position facing the end of the electrode. Claim 10 A battery assembly manufactured by the secondary battery manufacturing method according to claim 7. Claim 11 A secondary battery comprising a battery assembly according to claim 10. Claim 12 delete Claim 13 delete

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