Unit cell, secondary battery comprising unit cell, and battery module comprising secondary battery

Abstract

The present invention relates to a unit cell, a secondary battery comprising the unit cell, and a battery module comprising the secondary battery. The unit cell according to the present invention comprises: an electrode stack in which a first electrode, a separator, and a second electrode are alternately stacked; a first electrode tab extending from the first electrode; and a second electrode tab extending from the second electrode, wherein the first electrode and the second electrode are formed to have lengths greater than the widths thereof, the first electrode tab and the second electrode tab extend in the width directions of the first electrode and the second electrode, and the first electrode tab is provided on the first electrode in a number of at least two.

Description

A unit cell, a secondary battery including the unit cell, and a battery module including the secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0131839, filed October 4, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a unit cell, a secondary battery including the unit cell, and a battery module including the secondary battery.

[0005] Secondary batteries, unlike primary batteries, are rechargeable and have the potential for miniaturization and large capacity, leading to extensive research and development in recent years. With the rise in technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing.

[0006] Secondary batteries are attracting significant attention not only as an energy source for mobile devices such as cell phones, digital cameras, and laptops, but also as a power source for electric bicycles, electric cars, and hybrid electric vehicles. Small devices like cell phones and cameras use small battery packs containing a single battery cell, but medium- to large-sized devices like laptops and electric cars use battery modules consisting of two or more battery cells connected in parallel and / or series.

[0007] Secondary batteries are classified into coin-shaped, cylindrical, square, and pouch-shaped batteries, depending on the shape of their battery cases. Secondary batteries contain electrode assemblies and electrolytes. The electrode assemblies, mounted inside the battery case, are rechargeable, power-generating elements comprised of a laminated structure of electrodes and separators.

[0008] Electrode assemblies can be roughly classified into a jelly-roll type in which a separator is interposed between sheet-shaped positive and negative electrodes coated with active materials, a stack type in which a plurality of positive and negative electrodes are sequentially stacked with a separator interposed between them, and a stack-and-fold type in which stack-type unit cells are wound with a long separator film.

[0009] Recently, pouch-type batteries having a structure in which a stacked or stacked / folded electrode assembly is built into a pouch-type battery case made of aluminum laminate sheet have attracted much attention due to their low manufacturing cost, small weight, and easy shape deformation, and their usage is gradually increasing.

[0010] Conventional pouch cells have tabs located on both sides. However, because the tab width is small compared to the cell width, the current density is concentrated, increasing heat generation and causing the maximum cell temperature to appear. Furthermore, while increasing the tab width can lower the current density, it is limited to a small cell width. Furthermore, the distance between the positive and negative tabs increases, increasing the electron travel distance, increasing resistance and heat generation, which in turn increases the cell temperature and delays the rapid charging time.

[0011] One aspect of the present invention is to provide a unit cell capable of improving the maximum temperature and temperature deviation of the cell, a secondary battery including the unit cell, and a battery module including the secondary battery.

[0012] A unit cell according to an embodiment of the present invention includes an electrode stack in which a first electrode, a separator, and a second electrode are alternately stacked; a first electrode tab extending from the first electrode; and a second electrode tab extending from the second electrode, wherein the first electrode and the second electrode are formed to have a length greater than a width, the first electrode tab and the second electrode tab extend in the width direction of the first electrode and the second electrode, and at least two first electrode tabs may be provided on the first electrode.

[0013] In addition, a secondary battery according to an embodiment of the present invention includes an electrode assembly in which a plurality of unit cells according to an embodiment of the present invention are stacked; a pouch in which the electrode assembly is accommodated; a first electrode lead having one side connected to the first electrode tab and the other side extending to the outside of the pouch; and a second electrode lead having one side connected to the second electrode tab and the other side extending to the outside of the pouch, and ends of the first electrode tabs and the second electrode tabs of the plurality of stacked unit cells may be provided in a form in which tabs are joined to each other.

[0014] In addition, a battery module according to an embodiment of the present invention includes a battery stack in which a plurality of secondary batteries according to an embodiment of the present invention are stacked along a third direction, which is a stacking direction of the electrode stack; and a cooling unit positioned on a portion of the battery stack to cool the secondary batteries, wherein the portion may be positioned on an opposite side to a side where the first electrode tab and the second electrode tab are positioned based on the secondary batteries.

[0015] According to the present invention, the first electrode tab and the second electrode tab are extended in the width direction of the first electrode and the second electrode, which are formed to have a length greater than their width, and at least two first electrode tabs are provided within the first electrode, so that the distance between the tabs is shortened, thereby reducing resistance and suppressing temperature rise. Accordingly, the first electrode tab and the second electrode tab are extended in the width direction of the first electrode and the second electrode, and it is possible to form the tab width to be large, thereby lowering the current density and reducing the resistance.

[0016] In addition, since a plurality of first electrode tabs and a plurality of second electrode tabs protrude in a direction parallel to each other on one side of the four sides of the electrode laminate in which the first electrode, the separator, and the second electrode are alternately laminated, the current within the unit cell flows in at least three directions, so the current density is significantly lowered, and the resistance within the unit cell is significantly reduced, so that the heat generation and cell temperature can be significantly lowered.

[0017] In addition, a plurality of first electrode tabs and a plurality of second electrode tabs are alternately positioned along one of the four sides of the electrode stack, so that the resistance within the unit cell can be more significantly reduced, thereby significantly lowering the heat generation and cell temperature.

[0018] Figure 1 is a plan view showing a unit cell according to an embodiment of the present invention.

[0019] Figure 2 is an exploded perspective view showing a unit cell according to an embodiment of the present invention.

[0020] Figure 3 is a cross-sectional side view showing a secondary battery according to an embodiment of the present invention.

[0021] Figure 4 is a plan view showing a secondary battery according to an embodiment of the present invention.

[0022] Figure 5 is a plan view showing a battery module according to an embodiment of the present invention.

[0023] Figure 6 is a perspective view showing a battery module according to an embodiment of the present invention.

[0024] Figure 7 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Manufacturing Example 1.

[0025] Figure 8 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Manufacturing Example 2.

[0026] Figure 9 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Comparative Example 1.

[0027] Figure 10 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Comparative Example 2.

[0028] The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In this specification, when reference numerals are given to components in each drawing, it should be noted that, as far as possible, identical components are given the same reference numerals even if they are shown in different drawings. Furthermore, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

[0029]

[0030] FIG. 1 is a plan view showing a unit cell according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing a unit cell according to an embodiment of the present invention.

[0031] Referring to FIGS. 1 and 2, a unit cell (10) according to an embodiment of the present invention includes an electrode stack (S) in which a first electrode (11), a separator (13), and a second electrode (12) are alternately stacked, a first electrode tab (11a) extending from the first electrode (11), and a second electrode tab (11b) extending from the second electrode (12), and the first electrode (11) and the second electrode (12) are formed to have a length (L1, L2) greater than a width (W1, W2), and the first electrode tab (11a) and the second electrode tab (12a) extend in the width direction of the first electrode (11) and the second electrode (12).

[0032]

[0033] The electrode stack (S) is formed by alternately stacking at least one first electrode (11), at least one separator (13), and at least one second electrode (12). At this time, the electrode stack (S) can be sequentially stacked in a third direction (Z), which is the stacking direction, so that the first electrode (11), the separator (13), and the second electrode (12) correspond to each other.

[0034] Additionally, the electrode laminate (S) can be formed in a rectangular shape on a plane. The electrode laminate (S) is formed so that the length (L) is greater than the width (W).

[0035] Here, the first electrode (11) and the second electrode (12) may be an anode and a cathode, or a cathode and an anode.

[0036]

[0037] The first electrode (11) is formed so that the length (L2) is greater than the width (W1). At this time, the first electrode (11) may be formed in a rectangular shape, for example.

[0038] Additionally, the first electrode (11) may include a first electrode current collector and a first electrode active material laminated on one or both sides of the first electrode current collector.

[0039]

[0040] The first electrode tab (11a) extends from the first electrode (11) in the width direction of the first electrode (11).

[0041]

[0042] At this time, the width direction of the first electrode (11) may be the first direction (X), and the length direction of the first electrode (11) may be the second direction (Y). Here, the first direction (X) and the second direction (Y) may be perpendicular to each other on a plane.

[0043] Additionally, the first electrode tab (11a) may protrude, for example, in a square shape. That is, the first electrode tab (11a) may protrude from the first electrode (11) in the width direction of the first electrode (11).

[0044] In addition, a plurality of first electrode tabs (11a) may be provided on the first electrode (11). That is, at least two first electrode tabs (11a) may be provided on the first electrode (11). At this time, for example, two first electrode tabs (11a) may be provided on the first electrode (11).

[0045] And, the first electrode tab (11a) can be formed of the same material as the first electrode current collector of the first electrode (11).

[0046]

[0047] The second electrode (12) is formed so that its length (L2) is greater than its width (W2). At this time, the second electrode (12) may be formed in a rectangular shape, for example.

[0048] Additionally, the second electrode (12) may include a second electrode current collector and a second electrode active material laminated on one or both sides of the second electrode current collector.

[0049]

[0050] The second electrode tab (11b) extends from the second electrode (12) in the width direction of the second electrode (12).

[0051] At this time, the width direction of the second electrode (12) may be the first direction (X), and the length direction of the second electrode (12) may be the second direction (Y). Here, the first direction (X) and the second direction (Y) may be perpendicular to each other on a plane.

[0052] Additionally, the second electrode tab (11b) may protrude, for example, in a square shape. That is, the second electrode tab (11b) may protrude from the second electrode (12) in the width direction of the second electrode (12).

[0053] In addition, a plurality of second electrode tabs (12a) may be provided on the second electrode (12). That is, at least two second electrode tabs (12a) may be provided on the second electrode (12). At this time, for example, two second electrode tabs (12a) may be provided on the second electrode (12).

[0054] And, the second electrode tab (11b) can be formed of the same material as the second electrode current collector of the second electrode (12).

[0055]

[0056] The first electrode tab (11a) and the second electrode tab (12a) can protrude in a direction parallel to each other on one side (S1) of the four sides of the electrode laminate (S).

[0057] A plurality of first electrode tabs (11a) and a plurality of second electrode tabs (12a) can be alternately positioned along one side (S1) of the four sides of the electrode stack (S).

[0058] Among the plurality of first electrode tabs (11a), one first electrode tab (11a) may be positioned at one end of one side (S1) of the four sides of the electrode stack (S), and among the plurality of second electrode tabs (12a), one second electrode tab (12a) may be positioned at the other end of one side (S1) of the four sides of the electrode stack (S).

[0059] A plurality of first electrode tabs (11a) and a plurality of second electrode tabs (12a) may be positioned spaced apart from each other at a constant interval (D). At this time, a plurality of first electrode tabs (11a) and a plurality of second electrode tabs (12a) may be positioned spaced apart from each other at the same interval (D).

[0060] The lengths (L1-1, L2-1) protruding in the first direction (X), which is the width direction of the electrode stack (S), from the first electrode tab (11a) and the second electrode tab (12a) may be the same, and the widths (W1-1, W2-1) formed in the second direction (Y), which is the length direction of the electrode stack (S), from the first electrode tab (11a) and the second electrode tab (12a) may be the same.

[0061] Meanwhile, for example, the lengths (L1, L2) of the first electrode (11) and the second electrode (12) may have a ratio of 1.3 or more to the widths (W1, W2). Accordingly, since the lengths (L1, L2) of the first electrode (11) and the second electrode (12) are formed to have a large ratio of 1.3 or more to the widths (W1, W2), there is an effect of reducing temperature and resistance. And, specifically, for example, the lengths (L1, L2) of the first electrode (11) and the second electrode (12) may have a ratio of 1.3 to 5.4 to the widths (W1, W2).

[0062] In a plan view, the ratio of the width (W1-1) of the first electrode tab (11a) in the second direction (Y) perpendicular to the first direction (X) to the width (W1) of the first electrode (11) in the first direction (X), and the ratio of the width (W2-1) of the second electrode tab (12a) in the second direction (Y) perpendicular to the first direction (X) to the width (W2) of the second electrode (12) in the first direction (X) may be 0.05 to 0.15, respectively.

[0063] Accordingly, the ratio of the width (W1-1) of the first electrode tab (11a) and the width (W2-1) of the second electrode tab (12a) in the second direction (Y) perpendicular to the first direction (X) to the widths (W1, W2) of the first electrode (11) and the second electrode (12) in the first direction (X) is formed to be at least 0.05, which is the minimum value, thereby providing resistance and temperature reduction effects. In addition, the ratio of the width (W1-1) of the first electrode tab (11a) and the width (W2-1) of the second electrode tab (12a) in the second direction (Y) perpendicular to the first direction (X) to the widths (W1, W2) of the first electrode (11) and the second electrode (12) in the first direction (X) is formed to be at most 0.15, which is the maximum value, thereby preventing interference between the electrode tabs.

[0064] Meanwhile, the number of the plurality of first electrode tabs (11a) and the plurality of second electrode tabs (12a) extending to the first electrode (11) and the second electrode (12) may be the same. In this case, for example, the number of the plurality of first electrode tabs (11a) and the plurality of second electrode tabs (12a) may each be 2. Accordingly, direct connection may be possible by cross-arranging cells of one type.

[0065]

[0066] According to the embodiment of the present invention, the unit cell (10) configured as described above has a first electrode tab (11a) and a second electrode tab (12a) extending in the width direction of the first electrode (11) and the second electrode (12) formed to have a length (L1, L2) greater than the width (W1, W2), and at least two first electrode tabs (11a) are provided within the first electrode (11), so that the distance between the tabs is shortened, thereby reducing resistance and suppressing temperature rise. Accordingly, the first electrode tab (11a) and the second electrode tab (12a) extend in the width direction of the first electrode (11) and the second electrode (12), and it is possible to form the tab width large, thereby lowering the current density and reducing the resistance.

[0067] In addition, in the unit cell (10) according to the embodiment of the present invention, a plurality of first electrode tabs (11a) and a plurality of second electrode tabs (12a) protrude in a direction parallel to each other on one side (S1) of the four sides of the electrode stack (S) in which a first electrode (11), a separator (13), and a second electrode (12) are alternately stacked, so that the current within the unit cell (10) flows in at least three directions, thereby significantly lowering the current density and significantly reducing the resistance within the unit cell (10), thereby significantly lowering the amount of heat generated and the cell temperature.

[0068] In addition, in the unit cell (10) according to the embodiment of the present invention, a plurality of first electrode tabs (11a) and a plurality of second electrode tabs (12a) are alternately positioned along one side (S1) of the four sides of the electrode stack (S), so that the resistance within the unit cell (10) can be more significantly reduced, thereby more significantly lowering the amount of heat generated and the cell temperature.

[0069]

[0070] Below, a secondary battery according to an embodiment of the invention will be described.

[0071] Fig. 3 is a side cross-sectional view showing a secondary battery according to an embodiment of the present invention, and Fig. 4 is a plan view showing a secondary battery according to an embodiment of the present invention.

[0072] Referring to FIGS. 3 and 4, a secondary battery (100) according to an embodiment of the present invention includes an electrode assembly (110) in which a plurality of unit cells (10) are stacked, a pouch (120) in which the electrode assembly (110) is accommodated, a first electrode lead (131) having one side connected to a first electrode tab (11a) and the other side extending to the outside of the pouch (120), and a second electrode lead (132) having one side connected to a second electrode tab (11b) and the other side extending to the outside of the pouch (120).

[0073] A secondary battery (100) according to an embodiment of the present invention relates to a secondary battery (100) including a unit cell (10) according to the embodiment described above. Therefore, in this embodiment, overlapping content with the embodiment described above is omitted or briefly described, and differences are described.

[0074]

[0075] In more detail, referring to FIGS. 2 to 4, in a secondary battery (100) according to an embodiment of the present invention, the electrode assembly (110) is a power generation device capable of charging and discharging in which a plurality of unit cells (10) are stacked.

[0076] The unit cell (10) includes an electrode stack (S) in which at least one first electrode (11), at least one separator (13), and at least one second electrode (12) are alternately stacked, a first electrode tab (11a) extending from the first electrode (11), and a second electrode tab (11b) extending from the second electrode (12), and the first electrode (11) and the second electrode (12) are formed such that the length (L1, L2) is greater than the width (W1, W2), and the first electrode tab (11a) and the second electrode tab (12a) extend in the width direction of the first electrode (11) and the second electrode (12). (Reference Figure 1)

[0077] The first electrode tab (11a) may be provided in multiple numbers on the first electrode (11). That is, at least two first electrode tabs (11a) may be provided on the first electrode (11). At this time, for example, two first electrode tabs (11a) may be provided on the first electrode (11).

[0078] A plurality of second electrode tabs (12a) may be provided on the second electrode (12). That is, at least two second electrode tabs (12a) may be provided on the second electrode (12). At this time, for example, two second electrode tabs (12a) may be provided on the second electrode (12).

[0079] Meanwhile, the ends of the first electrode tabs (11a) and the second electrode tabs (11b) of the multiple stacked unit cells (10) may be provided in a form in which the tabs are joined to each other.

[0080]

[0081] The pouch (120) has a receiving portion formed therein so that the electrode assembly (110) can be received. The pouch (120) may include, for example, an aluminum sheet and a resin layer coated on both sides of the aluminum sheet.

[0082] The first electrode lead (131) may have one end connected to the first electrode tab (11a) and the other end extending to the outside of the pouch (120). In addition, the first electrode lead (131) may be welded to the end of the first electrode tab (11a) in which the tabs are assembled. The width (W1-1) of the first electrode tab (11a) and the width (W3) of the first electrode lead (131) may be the same.

[0083] The second electrode lead (132) may have one end connected to the second electrode tab (11b) and the other end extending to the outside of the pouch (120). In addition, the second electrode lead (132) may be welded to the end of the second electrode tab (11b) with the tabs gathered therein. The width (W2-1) of the second electrode tab (11b) and the width (W4) of the second electrode lead (132) may be provided to be the same.

[0084]

[0085] Hereinafter, a battery module according to an embodiment of the invention will be described.

[0086] FIG. 5 is a plan view showing a battery module according to an embodiment of the present invention, and FIG. 6 is a perspective view showing a battery module according to an embodiment of the present invention.

[0087] Referring to FIGS. 5 and 6, a battery module (1000) according to an embodiment of the present invention includes a battery stack (1100) in which a plurality of secondary batteries (100) are stacked along a third direction (Z), and a cooling unit (1200) positioned on a portion of the battery stack (1100) to cool the secondary batteries (100).

[0088] A battery module (1000) according to an embodiment of the present invention relates to a battery module (1000) including a secondary battery (100) according to the embodiment described above. Therefore, in this embodiment, any content overlapping with the embodiment described above will be omitted or briefly described, and differences will be described.

[0089]

[0090] In more detail, referring to FIGS. 2, 5, and 6, in the battery module (1000) according to the embodiment of the present invention, the battery stack (1100) is stacked in multiple pieces along the third direction (Z), which is the stacking direction of the electrode stack (S) of the secondary battery (100). Here, the third direction (Z) may be the stacking direction of the electrode stack (S) in which the first electrode (11), the separator (13), and the second electrode (12) are alternately stacked.

[0091] A secondary battery (100) may include an electrode assembly (110) in which a plurality of unit cells (10) are stacked, a pouch (120) in which the electrode assembly (110) is accommodated, a first electrode lead (131) having one side connected to a first electrode tab (11a) and the other side extending to the outside of the pouch (120), and a second electrode lead (132) having one side connected to a second electrode tab (11b) and the other side extending to the outside of the pouch (120).

[0092] The unit cell (10) includes an electrode stack (S) in which at least one first electrode (11), at least one separator (13), and at least one second electrode (12) are alternately stacked, a first electrode tab (11a) extending from the first electrode (11), and a second electrode tab (11b) extending from the second electrode (12), and the first electrode (11) and the second electrode (12) are formed to have a length (L1, L2) greater than a width (W1, W2), and the first electrode tab (11a) and the second electrode tab (12a) extend in the width direction of the first electrode (11) and the second electrode (12). (Reference Figure 1)

[0093] The first electrode tab (11a) may be provided in multiple numbers on the first electrode (11). That is, at least two first electrode tabs (11a) may be provided on the first electrode (11). At this time, for example, two first electrode tabs (11a) may be provided on the first electrode (11).

[0094] A plurality of second electrode tabs (12a) may be provided on the second electrode (12). That is, at least two second electrode tabs (12a) may be provided on the second electrode (12). At this time, for example, two second electrode tabs (12a) may be provided on the second electrode (12).

[0095]

[0096] The cooling unit (1200) is located on a part of the battery stack (1100) and can cool the secondary battery (100).

[0097] Here, a portion may be positioned on the opposite side to the side where the first electrode tab (11a) and the second electrode tab (12a) are positioned with respect to the secondary battery (100). At this time, the first electrode tab (11a) and the second electrode tab (12a) may be positioned on the upper side, and the cooling unit (1200) may be positioned on the lower side with respect to the secondary battery (100).

[0098] The cooling unit (1200) may include a cooling plate positioned at the bottom of the battery stack (1100).

[0099]

[0100] Meanwhile, the battery module (1000) according to an embodiment of the present invention may further include a module case that houses a battery stack (1100) and a cooling unit (1200) therein. In addition, the battery module (1000) according to an embodiment of the present invention may further include a plurality of secondary batteries (100) that are mutually stacked and a busbar that electrically connects the first electrode leads (131) and the second electrode leads (132) of the plurality of secondary batteries (100).

[0101]

[0102] < Manufacturing Example 1 >

[0103] A unit cell was manufactured including an electrode laminate in which a positive electrode, a separator, and a negative electrode are alternately laminated, a positive electrode tab extending from the positive electrode, and a negative electrode tab extending from the negative electrode.

[0104] In addition, the positive and negative electrodes were formed to be longer than their widths. Two positive tabs were formed on the positive electrode, and two negative tabs were formed on the negative electrode. The positive and negative tabs were formed to protrude in a direction parallel to each other on one of the four sides of the electrode laminate.

[0105] Additionally, two positive tabs were positioned on the left side of one of the four sides of the electrode stack, and two negative tabs were positioned on the right side of one of the four sides of the electrode stack.

[0106]

[0107] < Manufacturing Example 2 >

[0108] A unit cell was manufactured in the same manner as in Manufacturing Example 1, except that the two positive electrode tabs and the two negative electrode tabs were alternately positioned along one of the four sides of the electrode stack.

[0109]

[0110] < Comparative Example 1 >

[0111] A unit cell was manufactured in the same manner as in Manufacturing Example 1, except that one positive electrode tab and one negative electrode tab were positioned on both sides of the lengthwise direction of the electrode stack.

[0112]

[0113] < Comparative Example 2 >

[0114] A unit cell was manufactured in the same manner as in Manufacturing Example 1, except that two positive electrode tabs and two negative electrode tabs were positioned on both sides of the length direction of the electrode laminate.

[0115]

[0116] <Experimental Example 1>

[0117] Fig. 7 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Manufacturing Example 1, Fig. 8 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Manufacturing Example 2, Fig. 9 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Comparative Example 1, and Fig. 10 is an image showing the experimental results of temperature distribution according to electrical resistance in a unit cell according to Comparative Example 2. Here, the experimental results of Figs. 7 to 10 are simulation analysis results.

[0118] The temperature distribution of the unit cells according to Manufacturing Examples 1 and 2, Comparative Examples 1 and 2 are shown as images in Figs. 7 to 10. At this time, in the temperature distribution images of Manufacturing Examples 1 and 2 and Comparative Examples 1 and 2 shown in Figs. 7 to 10, the high temperature part is shown dark, and the low temperature part is shown bright, indicating light and shade.

[0119] The unit cell was charged at a 3C rate for 600 seconds, and the lower portion of the unit cell was cooled. The experiment was conducted at an initial temperature of 25°C, a cooling temperature of 25°C, and a cooling heat exchange coefficient of 500 W / mK, and the results are shown in Figures 7 to 10.

[0120] It can be seen that the temperature distributions of Manufacturing Example 1 shown in FIG. 7 and Manufacturing Example 2 shown in FIG. 8 are uniform and low, whereas the temperature distributions of Comparative Example 1 shown in FIG. 9 and Comparative Example 2 shown in FIG. 10 are uneven and high. Therefore, it can be seen that the current density is lower and the resistance is reduced in Manufacturing Examples 1 and 2, in which the positive and negative tabs are provided in the width direction, than in Comparative Examples 1 and 2, in which the positive and negative tabs are provided on both sides in the length direction in an electrode laminate in which positive and negative electrodes are laminated longer than in width.

[0121] And, in the case of the temperature distribution of Manufacturing Example 2 shown in FIG. 8, it can be seen that the temperature is more uniform and lower than that of Manufacturing Example 1 shown in FIG. 7. Accordingly, it can be seen that the current density is lower and the resistance is reduced in Manufacturing Example 2, in which two positive electrode tabs and two negative electrode tabs are alternately positioned along one of the four sides of the electrode laminate, compared to Manufacturing Example 1, in which two positive electrode tabs and two negative electrode tabs are alternately positioned along one of the four sides of the electrode laminate.

[0122] In particular, in an electrode laminate in which anodes and cathodes are laminated with a length longer than the width, it can be seen that the current density is significantly lowered and the resistance is significantly reduced in the manufacturing method 2 in which a plurality of first electrode tabs and a plurality of second electrode tabs extending in the width direction are alternately positioned along one of the four sides of the electrode laminate.

[0123]

[0124] <Experimental Example 2>

[0125] After applying current to the unit cells according to Manufacturing Example 1, Manufacturing Example 2, Comparative Example 1, and Comparative Example 2, the resistance was measured 10 seconds later and is shown in Table 1. The initial temperature, cooling temperature, cooling heat exchange coefficient, etc. were applied in the same manner as in Experimental Example 1. Table 1 shows the average value of the resistance measured at the electrode current collector portion of the electrode of the unit cell. The resistance listed in Table 1 is the ohmic resistance of the electrode current collector (foil).

[0126] 10-second resistance [mΩ] Manufacturing example 10.2 Manufacturing example 20.11 Comparative example 10.47 Comparative example 20.46

[0127] The resistance of Comparative Example 1 was 0.47 [mΩ], and that of Comparative Example 2 was 0.46 [mΩ], showing high resistance, whereas the resistance of Manufacturing Example 1 was 0.2 [mΩ], and that of Manufacturing Example 2 was 0.11 [mΩ], showing low resistance. Therefore, it can be seen that the resistance was reduced in Manufacturing Examples 1 and 2, in which the positive and negative tabs were provided in the width direction, compared to Comparative Examples 1 and 2, in which the positive and negative tabs were provided on both sides in the length direction in an electrode laminate in which positive and negative electrodes were laminated longer than in the width. In addition, it can be seen that the resistance of Manufacturing Example 2 was lower than that of Manufacturing Example 1. Therefore, it can be seen that the resistance is reduced in the second manufacturing example in which two positive tabs and two negative tabs are alternately positioned along one of the four sides of the electrode laminate, compared to the first manufacturing example in which two positive tabs and two negative tabs are alternately positioned along one of the four sides of the electrode laminate.

[0128] In particular, in an electrode laminate in which positive and negative electrodes having a length longer than their width are laminated, it can be seen that the resistance is significantly reduced in manufacturing 2 in which a plurality of first electrode tabs and a plurality of second electrode tabs extending in the width direction are alternately positioned along one of the four sides of the electrode laminate.

[0129]

[0130] While the present invention has been described in detail through specific examples, these are intended to illustrate the invention in detail and are not intended to be limiting. Those skilled in the art will appreciate that various implementations are possible within the technical scope of the present invention.

[0131] Additionally, the specific scope of protection of the invention will be made clear by the appended claims.

[0132]

[0133] [Explanation of symbols]

[0134] 10: Unit cell

[0135] 11: First electrode

[0136] 11a: First electrode tab

[0137] 12: Second electrode

[0138] 12a: Second electrode tab

[0139] 13: Membrane

[0140] 100: Secondary battery

[0141] 110: Electrode assembly

[0142] 120: Pouch

[0143] 131: First electrode lead

[0144] 132: Second electrode lead

[0145] 1000: Battery module

[0146] 1100: Battery stack

[0147] 1200: Cooling section

[0148] S: Electrode laminate

[0149] X: 1st direction

[0150] Y: Second direction

[0151] Z: Third direction

Claims

1. An electrode laminate in which a first electrode, a separator, and a second electrode are alternately laminated; a first electrode tab extending from the first electrode; and Including a second electrode tab extending from the second electrode, The first electrode and the second electrode are formed to have a length greater than a width, The first electrode tab and the second electrode tab extend in the width direction of the first electrode and the second electrode, A unit cell in which at least two of the first electrode tabs are provided on the first electrode.

2. In claim 1, The above first electrode tab and the above second electrode tab are unit cells that protrude in a direction parallel to each other on one of the four sides of the electrode laminate.

3. In claim 2, The above electrode laminate is formed in a rectangular shape, The above first electrode tab and the above second electrode tab are unit cells that protrude in a square shape.

4. In claim 2, A unit cell in which the first electrode tab and the second electrode tab are each provided in multiple numbers.

5. In claim 4, A unit cell in which a plurality of the first electrode tabs and a plurality of the second electrode tabs are alternately positioned along one of the four sides of the electrode stack.

6. In claim 5, A unit cell in which one of the first electrode tabs among the plurality of first electrode tabs is positioned at one end of one of the four sides of the electrode stack, and one of the second electrode tabs among the plurality of second electrode tabs is positioned at the other end of one of the four sides of the electrode stack.

7. In claim 5, A unit cell in which a plurality of the first electrode tabs and a plurality of the second electrode tabs are positioned at a constant interval from each other.

8. In claim 5, The lengths protruding in the first direction, which is the width direction of the electrode laminate, from the first electrode tab and the second electrode tab are equal to each other, A unit cell in which the widths formed in the second direction, which is the longitudinal direction of the electrode laminate, in the first electrode tab and the second electrode tab are the same.

9. In claim 8, A unit cell in which a ratio of the width of the first electrode tab in the second direction perpendicular to the first direction to the width of the first electrode tab in the first direction on a plan view, and a ratio of the width of the second electrode tab in the second direction perpendicular to the first direction to the width of the second electrode tab in the first direction are each 0.05 to 0.

15.

10. An electrode assembly in which a plurality of unit cells according to any one of claims 1 to 9 are stacked; A pouch in which the electrode assembly is accommodated; A first electrode lead having one end connected to the first electrode tab and the other end extending to the outside of the pouch; and A second electrode lead having one end connected to the second electrode tab and the other end extending to the outside of the pouch, A secondary battery in which the ends of the first electrode tabs and the second electrode tabs of the unit cells stacked in multiple pieces are provided in a tab-assembled form.

11. In claim 10, The width of the first electrode tab and the first electrode lead are the same, A secondary battery in which the widths of the second electrode tab and the second electrode lead are provided to be the same.

12. A battery stack in which a plurality of secondary batteries described in claim 10 are stacked along a third direction, which is the stacking direction of the electrode stack; and A cooling unit is positioned on a portion of the battery stack and includes a cooling unit for cooling the secondary battery, The above part is a battery module located on the opposite side to the side where the first electrode tab and the second electrode tab are located based on the secondary battery.

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