Secondary battery having multilayer electrode assembly and manufacturing method thereof

Abstract

The present invention relates to a secondary battery having a structure in which a plurality of electrode assemblies is stacked and a manufacturing method thereof. The technical problem to be solved is to propose a secondary battery having a structure in which a plurality of electrode assemblies is stacked within one battery case, so as to be alternatively utilized in an application of configuring and using a battery module / pack by stacking secondary batteries. To this end, the present invention provides a secondary battery comprising: a secondary battery case; a plurality of electrode assemblies which are vertically stacked and embedded in the case and each of which has an electrode tab; a current collecting part connected to each electrode tab of the plurality of stacked electrode assemblies; and a cap plate which is bonded to the case and with which a terminal connected to the current collecting part is assembled.

Description

Secondary battery having a multilayer electrode assembly and its manufacturing method

[0001] The present invention relates to a secondary battery, and more specifically, to a secondary battery having a structure in which a plurality of electrode assemblies are laminated, and a method for manufacturing the same.

[0002] Typically, a secondary battery is composed of an electrode assembly housed inside a case, a current collector connected to the electrode tabs (positive tab and negative tab) of the electrode assembly, and a terminal connected to the current collector and exposed to the outside. The electrode assembly is manufactured by winding or laminating positive and negative electrode plates and a separator. The current collector is connected to the electrode tabs formed on the positive and negative electrode plates of the electrode assembly and is electrically connected to the terminal.

[0003] With the proliferation of electric vehicles and energy storage systems (ESS), the capacity of secondary batteries is increasing. To address this, multiple secondary batteries can be assembled into modules or packs, increasing their capacity. Furthermore, so-called "tall cell" secondary batteries, which increase capacity by extending their vertical length (height) relative to their horizontal length, are also being used.

[0004] The above-described information disclosed in the background technology of this invention is only intended to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0005] The purpose of the present invention is to propose a secondary battery having a structure in which a plurality of electrode assemblies are stacked within a single battery case so that it can be used as an alternative in applications in which secondary battery products are stacked to form a battery module / pack.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] In order to solve the above technical problem, according to one aspect of the present invention, a secondary battery is provided, which includes a secondary battery case; a plurality of electrode assemblies vertically stacked and built into the case, each having an electrode tab formed thereon; a current collector connected to each electrode tab of the plurality of stacked electrode assemblies; and a cap plate joined to the case and having a terminal connected to the current collector assembled thereon.

[0008] In addition, according to another aspect of the present invention for solving the above technical problem, a method for manufacturing a secondary battery is provided, including the steps of preparing a plurality of electrode assemblies; manufacturing a case in which the plurality of electrode assemblies are built; manufacturing a current collector connecting the plurality of electrode assemblies and terminals; manufacturing a cap plate on which the current collector and terminal are assembled; and vertically stacking the plurality of electrode assemblies to connect the current collector to each electrode assembly and connecting the cap plate to the terminal.

[0009] According to the present invention, by stacking a plurality of electrode assemblies within a single battery case to form a secondary battery, compatibility with existing electrode assemblies is possible, thereby achieving the effects of process simplification, reduction in material management burden, and reduction in production costs.

[0010] In addition, it can be used as a replacement for applications such as electric trucks that previously used modules / packs made by stacking secondary batteries in two or more layers, and thus can contribute to weight reduction, miniaturization, and price reduction of such applications.

[0011] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0012] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in the drawings.

[0013] Figure 1 is a top perspective view of a square secondary battery.

[0014] Figure 2 is a cross-sectional view II' of Figure 1, showing the inside of a secondary battery with a side tab structure.

[0015] Figure 3 is a cross-sectional view II' of Figure 1, showing the inside of a secondary battery with a top tab structure.

[0016] Figure 4 illustrates a secondary battery (tall cell) with an extended vertical length compared to the horizontal length.

[0017] Figures 5 and 6 schematically illustrate the configuration of a secondary battery according to one embodiment of the present invention, with Figure 5 being a cross-sectional view of an assembled state and Figure 6 being an exploded view before case installation.

[0018] FIG. 7 is an equivalent circuit of a secondary battery according to one embodiment of the present invention shown in FIGS. 5 and 6.

[0019] Fig. 8 is a cross-sectional view of a secondary battery including a collector having a modified shape compared to Fig. 5.

[0020] Figure 9 is an equivalent circuit diagram of the secondary battery shown in Figure 8.

[0021] Figure 10 is a schematic diagram of the internal cross-section of a secondary battery additionally including a three-layer electrode assembly according to another embodiment of the present invention.

[0022] Fig. 11 is an equivalent circuit diagram of a secondary battery according to the embodiment shown in Fig. 10.

[0023] FIG. 12 and FIG. 13 are cross-sectional views and exploded views showing another embodiment of a secondary battery including a multilayer laminated electrode assembly according to the present invention.

[0024] Figure 14 is an exemplary diagram of a secondary battery module in which secondary batteries manufactured according to the present invention are arranged.

[0025] Fig. 15 is an example diagram of a secondary battery pack including the secondary battery module of Fig. 14.

[0026] Fig. 16 is a conceptual diagram of a vehicle including the secondary battery pack of Fig. 15.

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0028] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements, and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements, and / or groups thereof.

[0029] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0030] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given range may also mean uniformity on average.

[0031] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0032] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0033] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0034] Additionally, when a component is described as being "on," "connected to," or "coupled to" another component, it should be understood that the components may be directly connected or coupled to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through other components.

[0035] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, the use of "may" when describing embodiments of the present invention refers to "one or more embodiments of the present invention." Expressions such as "one or more" and "one or more" preceding a list of elements modify the list as a whole and do not modify individual elements within the list.

[0036] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated, and when reference is made to “C through D,” this means C or more and D or less, unless otherwise stated.

[0037] When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group A, B, and C," or "at least one selected from A, B, and C," are used to specify a list of elements A, B, and C, the phrases can refer to any suitable combination.

[0038] The term "use" may be considered synonymous with the term "utilize." As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation rather than degrees, and are intended to take into account inherent variations in measured or calculated values ​​that would be recognized by those skilled in the art.

[0039] Although terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or cross-section from another element, component, region, layer, or cross-section. Thus, a first element, component, region, layer, or section discussed below could also be termed a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0040] For ease of description, spatially relative terms such as "beneath," "below," "lower," "above," and "upper" may be used in the specification to describe the relationship of one element or feature to other elements or features as depicted in the drawings. It will be understood that spatially relative positions encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the drawings is turned over, other elements are understood to be "beneath" or "below," and the depicted elements are understood to be "above" or "above" other elements. Thus, the term "beneath" can encompass both the above and below orientations.

[0041] The terms used herein are for the purpose of describing embodiments of the invention and are not intended to limit the invention.

[0042] Figure 1 is a top perspective view showing the appearance of a secondary battery.

[0043] The case (51) forms the overall appearance of the secondary battery and may be formed of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. In addition, the case (51) may provide a space in which the electrode assembly is accommodated.

[0044] The cap assembly (60) may include a cap plate (61) covering the opening of the case (51), and the case (60) and the cap plate (61) may be made of a conductive material. Here, the first terminal (63) and the second terminal (62) may be installed to protrude outward by penetrating the cap plate (61) and being electrically connected to the positive or negative electrode plate inside.

[0045] An electrolyte injection port (64) into which a sealing plug can be installed can be formed in the cap plate (61), and a vent (66) having a notch (65) formed therein can be installed. The vent (66) is for degassing gas generated inside the battery.

[0046] Fig. 2 is a cross-sectional view II' of Fig. 1, showing the internal structure of a secondary battery according to one type. The illustrated secondary battery basically includes an electrode assembly (40), a first current collector (41), a first terminal (62), a second current collector (42), a second terminal (63), and a cap assembly (60).

[0047] The electrode assembly (40) can be manufactured as a laminate in which a first electrode plate, a separator, and a second electrode plate formed in a plate shape or a film shape are wound or laminated. When the electrode assembly (40) is a wound laminate (also known as a jelly roll), the winding axis can be parallel to the longitudinal direction of the case. In addition, the electrode assembly (40) may be a stack type rather than a wound type. However, the shape of the electrode assembly (40) is not limited in the present invention. In addition, the electrode assembly (40) can be a Z-stack electrode assembly in which the first electrode plate and the second electrode plate are inserted on both sides of a separator bent in a Z shape. In addition, the electrode assembly (40) can be stored inside the case by stacking one or more electrode assemblies so that their long sides are adjacent to each other, and the number of electrode assemblies is not limited in the present invention. The first electrode plate of the electrode assembly (40) can serve as a cathode and the second electrode plate can serve as an anode, or vice versa.

[0048] The first electrode plate is formed by applying a first electrode active material such as graphite or carbon to a first electrode current collector (substrate) formed of a metal foil such as copper, copper alloy, nickel or nickel alloy, and may include a first electrode tab (or first uncoated region) which is a region where the first electrode active material is not applied. The first electrode tab (43) may be a passage for current flow between the first electrode plate and the first current collector (41). In some examples, the first electrode tab (43) may be formed by cutting the first electrode plate in advance so as to protrude to one side when manufacturing the first electrode plate, and may protrude further to one side than the separator without separate cutting.

[0049] The second electrode plate is formed by applying a second electrode active material such as a transition metal oxide to a substrate formed of a metal foil such as aluminum or an aluminum alloy, and may include a second electrode tab (or second non-coated portion) (44) which is a region where the second electrode active material is not applied. The second electrode tab (44) may be a passage for current flow between the second electrode plate and the second current collector (42). In some examples, the second electrode tab (44) may be formed by cutting the second electrode plate in advance so as to protrude to the other side when manufacturing the second electrode plate, and may protrude further to the other side than the separator without separate cutting.

[0050] In some embodiments, the first electrode tab (43) may be positioned on the right side of the electrode assembly (40), and the second electrode tab (44) may be positioned on the left side of the electrode assembly (40), or may be positioned on one side in the same direction. Also, in some embodiments, the first electrode tab (43) and the second electrode tab (44) may be positioned on the upper portion of the electrode assembly (40).

[0051] Here, left, right, and top are for convenience of explanation based on the secondary battery illustrated in Fig. 1, and their positions may change when the secondary battery rotates left, right, or up and down.

[0052] The separator functions to prevent short circuiting between the first and second electrode plates while allowing the movement of lithium ions. The separator may be composed of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, or the like.

[0053] The first electrode tab (43) of the first electrode plate and the second electrode tab (44) of the second electrode plate extend from both ends of the electrode assembly (40) as described above. In some embodiments, the electrode assembly (40) may be accommodated in a case (51) together with an electrolyte.

[0054] In the electrode assembly (40), the first electrode tabs (43) and the second electrode tabs (44) extending from the first electrode plate and the second electrode plate to both sides can be connected to the first collector (41) and the second collector (42) by welding, respectively. In some embodiments where the first electrode tabs (43) and the second electrode tabs (44) are positioned at the upper portion of the electrode assembly (40) as mentioned above, the first collector and the second collector are positioned at the upper portion of the electrode assembly (40).

[0055] The first collector (41) and the second collector (42) are respectively connected to the first terminal (62) and the second terminal (63) described in Fig. 1 through a connecting member (67). In some embodiments, the outer circumferential surface of the connecting member (67) may be threaded and may be fastened to the first terminal (62) and the second terminal (63) through a screw connection. However, the present invention is not limited thereto, and the connecting member (67) may also be connected to the first terminal (62) and the second terminal (63) by riveting or welding.

[0056] The secondary battery shown in FIG. 2 above has a structure in which the electrode assembly (40) is arranged so that the first electrode tab (43) and the second electrode tab (44) of the electrode assembly (40) are located on both sides of the secondary battery, and this structure is called a side-tab structure.

[0057] Fig. 3 is an exemplary diagram of a secondary battery having an internal structure different from that of Fig. 2. Fig. 3 illustrates a top-tab structure in which an electrode assembly (40') is arranged so that a first electrode tab (43') and a second electrode tab (44') are positioned on the upper portion of the secondary battery.

[0058] The secondary battery with the top tab structure shown in Fig. 3 has a structure in which the first electrode tab (43') and the second electrode tab (44') of the electrode assembly (40') are positioned at the upper portion of the case (51'), the first current collector (41') and the second current collector (42') are respectively connected thereto, and the first terminal (62') and the second terminal (62') connected to each current collector (41', 42') are installed on the outside of the cap plate (61'). The other configuration is similar to the secondary battery with the side tab structure shown in Fig. 2.

[0059] Fig. 4 shows a secondary battery in a form in which the vertical length is extended compared to the horizontal length. A secondary battery having an appearance in which the vertical length is relatively long is also called a 'tall cell'. Fig. 4 schematically illustrates a tall cell having a top tab structure in which electrode tabs (43", 44") are positioned on the upper surface of an electrode assembly (40"). In addition, in the tall cell, when the length of the cap plate (61") is short and the space is narrow, a vent (66") can be installed at the bottom of the case (51"), but is not limited thereto.

[0060] Tall cells can be used as an alternative in applications (e.g., electric trucks) that use battery modules / packs by stacking two or more layers of "horizontal rectangular secondary batteries" with a small length-to-width ratio, such as those in Fig. 1. However, since the vertical length of the internal electrode assembly in tall cells increases, when a side-tab structure is applied, the winding or stacking process for manufacturing the electrode assembly becomes more complicated, and there is a disadvantage in that it is difficult to be compatible with the electrode assembly for horizontal rectangular batteries. In addition, when a top-tab structure is applied to tall cells, the utilization of the upper space of the battery is reduced and the battery capacity may be sacrificed due to the electrode tabs, current collectors, and related members that must be located at the upper part of the electrode assembly.

[0061] Figures 5 and 6 schematically illustrate the configuration of a secondary battery according to one embodiment of the present invention. Figure 5 is a cross-sectional view of an electrode assembly (200, 300) and related components and a cap plate (130) assembled to a case (100). Figure 6 illustrates a state in which a plurality of electrode assemblies (200, 300) are vertically stacked, current collectors (110, 120) are connected to electrode tabs (210, 310 and 220, 320) formed on both sides thereof, and terminals (140, 150) are connected to the outer surface (upper surface) of the cap plate (130) (representing a state before being built into the case (100).

[0062] As shown in FIGS. 5 and 6, according to one embodiment of the present invention, a first-layer electrode assembly (200) and a second-layer electrode assembly (300) can be erected and vertically stacked within a case (100).

[0063] As illustrated, the secondary battery of this embodiment may be implemented with a side-tab structure. For example, the first electrode tab (210) and the second electrode tab (220) of the first-layer electrode assembly (200) may be arranged so that they are positioned on opposite sides of the case (100). Similarly, the second-layer electrode assembly (300) may be arranged so that the first electrode tab (310) and the second electrode tab (320) are positioned on opposite sides of the case (100).

[0064] A first terminal (140) and a second terminal (150) can be assembled to a cap plate (130) that is joined to the upper part of the case (100), and each terminal can be electrically connected to a first collector (110) and a second collector (120).

[0065] The first current collector (110) is connected to the first electrode tab (210) of the first-layer electrode assembly (200) and the first electrode tab (310) of the second-layer electrode assembly (300), and its uppermost portion can be connected to the first terminal (140). Similarly, the second current collector (120) is connected to the second electrode tab (220) of the first-layer electrode assembly (200) and the second electrode tab (320) of the second-layer electrode assembly (300), and its uppermost portion can be connected to the second terminal (150).

[0066] An insulator (170) may be interposed between the first-layer electrode assembly (200) and the second-layer electrode assembly (300). This insulator (170) may serve to strengthen electrical insulation between the first- and second-layer electrode assemblies (200, 300) and to prevent mutual heat transfer.

[0067] In one embodiment, the secondary battery may be implemented in a tall cell shape as illustrated in FIG. 5, and a vent (160) may be positioned at the bottom of the case (100). However, it is also possible to implement it in a shape other than a tall cell (for example, a horizontal rectangular shape as illustrated in FIG. 2), and it is also possible to implement it as a secondary battery in which the vent (160) is positioned at the top (see FIG. 12).

[0068] In the embodiment of FIG. 5, the first and second layer electrode assemblies (200, 300) stacked vertically are compatible with existing single layer electrode assemblies, so that each electrode assembly (200, 300) can be manufactured using the same manufacturing equipment as existing ones. Here, each electrode assembly (200, 300) may be a wound type (so-called jelly roll) of electrode plates (including a positive electrode, a separator, and a negative electrode), or may be a stack type or Z stack type of electrode plates.

[0069] FIG. 7 is an equivalent circuit of a secondary battery according to one embodiment of the present invention shown in FIGS. 5 and 6.

[0070] First, it is assumed that the basic line resistance of the first collector (110) connecting the first terminal (140) and the first-layer electrode assembly (200) and the second-layer electrode assembly (300) is r1,1, and the basic line resistance of the second collector (120) connecting the second terminal (150) and the first-layer electrode assembly (200) and the second-layer electrode assembly (300) is r2,1.

[0071] Structurally, since the first-layer electrode assembly (200) and the second-layer electrode assembly (300) are vertically stacked, as shown in FIGS. 5 and 6, the lengths of the first collector (110) and the second collector (120) extend from the second layer to the first layer, so that an additional line resistance r1,2 can be added to the basic line resistance r1,1 of the first collector (110), and an additional line resistance r2,2 can be added to the basic line resistance r2,1 of the second collector (120). That is, the line resistances from the first and second collectors (110, 120) to the second-layer electrode assembly (300) can be r1,1 and r2,1, respectively, and the line resistances to the first-layer electrode assembly (200) can be [r1,1 + 1,2] and [r2,1 + r2,2], respectively.

[0072] In this way, since the length of the current collectors on both sides is extended vertically, as the current path increases, the line resistance for each layer electrode assembly (200, 300) may accumulate, and this may cause a resistance imbalance between the first layer electrode assembly (200) and the second layer electrode assembly (300), resulting in a difference in current density and deterioration between the electrode assemblies.

[0073] To solve this problem and maintain the resistance balance between the upper and lower electrode assemblies, according to one embodiment, each electrode assembly can be manufactured so that the resistance of the first-layer electrode assembly (200) and the second-layer electrode assembly (300) are different. For example, the electrode assembly can be manufactured so that the resistance of the first-layer electrode assembly (200) is lower than the resistance of the second-layer electrode assembly (300). However, in another embodiment, a plurality of electrode assemblies can be used in which the resistances are all the same.

[0074] According to another embodiment for maintaining resistance balance between the upper and lower electrode assemblies, the number of electrode plate turns or stacks of the two-layer electrode assembly (300) and the number of electrode plate turns or stacks of the one-layer electrode assembly (200) can be manufactured so that each electrode assembly (200, 300) is different. For example, by reducing the number of electrode plate turns or stacks of the two-layer electrode assembly (300) on the upper side, the capacity can be the same but the resistance of the electrode assembly can be increased, and by increasing the number of electrode plate turns or stacks of the one-layer electrode assembly (200) on the lower side, the capacity can be the same but the resistance of the electrode assembly can be lowered.

[0075] According to another embodiment for maintaining resistance balance between upper and lower electrode assemblies, the first-layer electrode assembly (200) and the second-layer electrode assembly (300) may be used with the same number of electrode plates or stacks, but the shape of the current collector may be changed. This embodiment is illustrated in Fig. 8.

[0076] The secondary battery illustrated in Fig. 8 has a modified current collector shape compared to the embodiment of Fig. 5. Specifically, the first current collector connecting the first terminal (140) and the first-layer electrode assembly (200) and the second-layer electrode assembly (300) may be configured with a main line (114) connected to the first terminal (140), a first branch line (112) branched from the end of the main line (114) and connected to the first electrode tab (310) of the second-layer electrode assembly (300), and a second branch line (113) branched from the end of the main line (114) and connected to the first electrode tab (210) of the first-layer electrode assembly (200). The point at which the first branch line (112) and the second branch line (113) branch from the main line (114) is indicated as a branch point 116.

[0077] Similarly, the second current collector connecting the second terminal (150) and the first-layer electrode assembly (200) and the second-layer electrode assembly (300) may be composed of a main line (124) connected to the second terminal (150), a first branch line (122) branched from an end of the main line (124) and connected to a second electrode tab (320) of the second-layer electrode assembly (300), and a second branch line (123) branched from an end of the main line (124) and connected to a second electrode tab (220) of the first-layer electrode assembly (200). The point at which the first branch line (122) and the second branch line (123) branch from the main line (124) is shown as a branch point 126.

[0078] In Fig. 8, the structure of the first and second collectors is conceptually explained, but in actual implementation, the structure can be designed to minimize the space occupied by these collectors within the case.

[0079] Fig. 9 is an equivalent circuit diagram of a secondary battery to which first and second collectors having the same structure as Fig. 8 are applied.

[0080] Since the first branch line (112) and the second branch line (113) are branched with the same length from the main line (114) connected to the first terminal (140), only the basic line resistance r1,1 of the main line (114) can exist, and in the branch lines 112 and 113 connected to the first-layer electrode assembly (200) and the second-layer electrode assembly (300), respectively, only the respective line resistances may exist, but there can be no line resistance imbalance between them.

[0081] Also, on the opposite side, since the first branch line (122) and the second branch line (123) are branched with the same length from the main line (124) connected to the second terminal (150), only the basic line resistance r2,1 of the main line (124) exists, and the branch lines 122 and 123, which are connected to the first-layer electrode assembly (200) and the second-layer electrode assembly (300), respectively, only have their own line resistances, and there cannot be an imbalance in line resistance between them.

[0082] Figure 10 is a schematic diagram of the internal cross-section of a secondary battery further including a three-layer electrode assembly according to another embodiment of the present invention. A three-layer electrode assembly (400) is additionally laminated on top of the one-layer electrode assembly (200) and the two-layer electrode assembly (300) described above.

[0083] The first current collector (110) is connected to all of the first electrode tab (210) of the first-layer electrode assembly (200), the first electrode tab (310) of the second-layer electrode assembly (300), and the first electrode tab (410) of the third-layer electrode assembly (400), and its uppermost portion can be connected to the first terminal (140). Similarly, the second current collector (120) is connected to all of the second electrode tab (220) of the first-layer electrode assembly (200), the second electrode tab (320) of the second-layer electrode assembly (300), and the second electrode tab (420) of the third-layer electrode assembly (400), and its uppermost portion can be connected to the second terminal (150).

[0084] An insulator 170 may be interposed between the first-layer electrode assembly (200) and the second-layer electrode assembly (300), and an insulator 172 may be interposed between the second-layer electrode assembly (300) and the third-layer electrode assembly (400). As mentioned above, these insulators (170, 172) are for electrical insulation and heat insulation between the respective electrode assemblies (200, 300, 400).

[0085] Fig. 11 is an equivalent circuit of a secondary battery according to the embodiment shown in Fig. 10.

[0086] Since the 1st, 2nd, and 3rd layer electrode assemblies (200) are vertically stacked, the lengths of the first collector (110) and the second collector (120) extend from the 3rd layer to the 1st layer. Accordingly, additional line resistances r1,2 and r1,3 can be added to the basic line resistance r1,1 of the first collector (110), and additional line resistances r2,2 and r2,3 can be added to the basic line resistance r2,1 of the second collector (120).

[0087] As a way to solve the problem of resistance imbalance between each electrode assembly (200, 300, 400) due to the accumulated line resistance as the length of the collectors on both sides increases, as described above, each electrode assembly (200, 300, 400) can be manufactured so that the number of electrode plate turns or stacks of the three-layer electrode assembly (400), the number of electrode plate turns or stacks of the two-layer electrode assembly (300), and the number of electrode plate turns or stacks of the one-layer electrode assembly (200) are different. For example, by increasing the number of electrode plate turns or stacks from the upper layer to the lower layer, the capacity can be maintained the same and the resistance can be reduced. That is, [the number of electrode plate windings or stacks of the 3-layer electrode assembly (400)] < [the number of electrode plate windings or stacks of the 2-layer electrode assembly (400)] < [the number of electrode plate windings or stacks of the 1-layer electrode assembly (400)].

[0088] FIG. 12 and FIG. 13 are a cross-sectional schematic diagram and an exploded perspective view thereof showing another embodiment of a secondary battery including a multilayer laminated electrode assembly according to the present invention.

[0089] This embodiment shows that the idea of ​​the present invention is implemented in a horizontal rectangular secondary battery (see FIGS. 1 and 2) rather than the tall cell type secondary battery described above (see FIGS. 4, 5 and 6).

[0090] A two-layer electrode assembly (300') is stacked on top of a jelly roll-shaped one-layer electrode assembly (200') in which an electrode plate is wound, and an insulator (170') may be interposed between them.

[0091] The first current collector (110') is connected to the first electrode tab (210') of the first-layer electrode assembly (200') and the first electrode tab (310') of the second-layer electrode assembly (300'), and its uppermost portion can be connected to the first terminal (140'). In addition, the second current collector (120') is connected to the second electrode tab (220') of the first-layer electrode assembly (200') and the second electrode tab (320') of the second-layer electrode assembly (300'), and its uppermost portion can be connected to the second terminal (150').

[0092] In this embodiment, unlike the tall cell shape of FIG. 5, it can be seen that the vent (160') is installed on the upper cap plate (130').

[0093] Even in the present embodiment, an issue of resistance imbalance may occur due to the extension of the length of the current collector (110', 120'), and the countermeasures therefor are similar to those described above. That is, the number of turns of the electrode plates of the two-layer electrode assembly (300') and the number of turns of the electrode plates of the one-layer electrode assembly (200') can be manufactured so that each electrode assembly (200', 300') has a different number of turns. For example, by reducing the number of turns of the electrode plates of the two-layer electrode assembly (300') on the upper side, the capacity can be the same but the resistance of the electrode assembly can be increased, and by increasing the number of turns of the electrode plates of the one-layer electrode assembly (200') on the lower side, the capacity can be the same but the resistance of the electrode assembly can be lowered. In addition, as illustrated in FIG. 8, the one-layer electrode assembly (200') and the two-layer electrode assembly (300') can use the same number of turns, but the shape of the current collector can be changed.

[0094] The embodiments described above are examples of two-layer stacking of two electrode assemblies and three-layer stacking of three electrode assemblies, but the idea of ​​the present invention can be generalized to stacking N layers of two or more arbitrary number N electrode assemblies. The N-layer stacking structure of the N electrode assemblies and the structure of the current collector and related components can be easily configured by those skilled in the art.

[0095] Now, a secondary battery manufacturing method according to the present invention will be described. The secondary battery manufacturing method of the present invention can be easily inferred from the secondary battery structure described above, in which N electrode assemblies are vertically stacked in N layers within a case. Therefore, the following description of the manufacturing method will be outlined with reference to the previously described drawings and related content.

[0096] The method for manufacturing a secondary battery of the present invention may include the steps of: preparing a plurality of electrode assemblies including electrode tabs; manufacturing a case in which the plurality of electrode assemblies are built; manufacturing a current collector that is connected to each electrode tab of the plurality of electrode assemblies and connects the electrode tab and a terminal; manufacturing a cap plate on which the current collector and the terminal are assembled; vertically stacking the plurality of electrode assemblies to connect the current collector to each electrode tab and connect the current collector to the terminal at the cap plate; and building the vertically stacked electrode assemblies and the current collector into the case and bonding the cap plate to the case.

[0097] Explain each step.

[0098] In the step of preparing a plurality of electrode assemblies, the electrode assemblies can be manufactured in a coiled (jelly roll) type, a stack type, or a Z-stack type. The electrode tabs of the electrode assemblies can be formed to provide a secondary battery with a side tab structure, but are not limited thereto.

[0099] The electrode assembly may be manufactured so that the capacities of the plurality of electrode assemblies are the same, but is not limited thereto. The resistance of the electrode assemblies may be different for each electrode assembly. For example, the electrode assembly may be manufactured so that the resistance of the electrode assembly located in the lower layer is smaller than the resistance of the electrode assembly located in the upper layer. However, in another embodiment, the resistances of the plurality of electrode assemblies may all be the same. The number of electrode plate turns or stacks of the electrode assemblies may be different for each electrode assembly. For example, the number of electrode plate turns or stacks of the electrode assembly located in the upper layer may be smaller than the number of electrode plate turns or stacks of the electrode assembly located in the lower layer. However, in another embodiment, the number of electrode plate turns or stacks of the electrode assemblies of the plurality of electrode assemblies may be the same.

[0100] In the case manufacturing stage, the case may be a case for a secondary battery with an extended vertical length relative to its horizontal length, a so-called tall cell case (see Fig. 4), but is not limited thereto. For example, it may be a case for a horizontally rectangular secondary battery, such as that in Fig. 2 (see Figs. 12 and 13).

[0101] In the step of manufacturing the current collector, the current collector may be connected to each electrode tab of a plurality of electrode assemblies to connect the corresponding electrode tabs and external terminals. The current collector may be formed in pairs so as to be connected to the electrode tabs formed on both sides of the plurality of vertically stacked electrode assemblies, and may be manufactured with an extended length corresponding to the vertical height of the multi-layered electrode assemblies (see FIGS. 5, 6, and 10). In another embodiment, the current collector may be composed of a main line connected to a terminal, and branch lines branched from the main line and connected to each electrode tab of each electrode assembly, as shown in FIG. 8.

[0102] In the manufacturing step of the cap plate on which the collector and terminal are assembled, the cap plate may or may not include a vent (e.g., in the case of a toll cell). The cap plate may also have a filler hole formed therein for injecting electrolyte after being bonded to the case.

[0103] In the step of vertically stacking a plurality of electrode assemblies, connecting a current collector to each electrode tab, and connecting the electrode tab to a terminal on the cap plate, the current collector may be located on a surface of the cap plate that faces the inside of the case, and the terminal may be located on an outer surface of the cap plate (refer to FIGS. 5, 6, and 12 for the connection relationship between the electrode tab, current collector, terminal, and cap plate of the electrode assembly). When stacking the electrode assemblies, an insulator may be interposed between the electrode assemblies.

[0104] A description is given of materials that can be used in a secondary battery according to the present invention.

[0105] A compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) can be used as a cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0106] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0107] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG bO2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0108] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0109] A positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0110] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0111] Al may be used as the positive electrode current collector, but is not limited thereto.

[0112] Meanwhile, the negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0113] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0114] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 <x<2), Si계 합금, 또는 이들의 조합일 수 있다.

[0115] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0116] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0117] A negative electrode for a lithium secondary battery includes a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0118] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0119] The above binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included.

[0120] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0121] The electrolyte for a lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0122] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0123] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more thereof.

[0124] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0125] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Such separators may include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film comprising two or more layers of these materials.

[0126] The separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0127] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0128] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from, but not limited to, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0129] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0130] Figure 14 is an exemplary diagram of a secondary battery module in which secondary batteries manufactured using a manufacturing method according to the present invention are arranged. In accordance with the need for high-capacity secondary batteries for driving electric vehicles and the like, a secondary battery module is manufactured by arranging and connecting a plurality of secondary battery cells in a horizontal and / or vertical direction. A plurality of secondary batteries are arranged in a space formed by a pair of opposing end plates (71a, 71b) and a pair of opposing side plates (72a, 72b). The arrangement of the secondary batteries can be designed in terms of the arrangement direction and number to obtain desired voltage and current specifications.

[0131] Fig. 15 is an exemplary diagram of a secondary battery pack (80) configured to apply the square secondary battery module illustrated in Fig. 14 to an actual product (e.g., an automobile). The secondary battery pack can be manufactured by embedding a plurality of secondary battery modules in a pack housing designed to be mounted on an actual product. The pack housing may include fasteners and electrical outlets necessary for mounting on a product. In Fig. 11, for convenience of illustration, bus bars for electrical connection of secondary batteries, a cooling unit, external terminals, and other related elements are omitted.

[0132] A secondary battery pack can be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheel drive or two-wheel drive vehicle. FIG. 16 is a drawing illustrating a vehicle including the secondary battery pack illustrated in FIG. 15. FIG. 16 illustrates a secondary battery pack (80) according to an embodiment of the present invention mounted on the lower body of a vehicle (V). The vehicle (V) operates by receiving power from the secondary battery pack (80) according to an embodiment of the present invention.

[0133] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0134] <Explanation of symbols>

[0135] 40 40' 40": electrode assembly, 41 41': first current collector, 42 42': second current collector, 43 43' 43": first electrode tab, 44 44' 44": second electrode tab, 50: cap assembly, 51 51' 51": case, 60: cap assembly, 61 61' 61": cap plate, 62 62': first terminal, 63 63': second terminal, 64: electrolyte injection port, 65: notch, 66 66": vent, 67: connecting member, 71a 71b: end plate, 72a 72b: side plate, 80: secondary battery pack, 100: case, 110 110': first collector, 112: first branch line, 113: second branch line, 114: main line, 116: branch point, 120 120': second collector, 122: first branch line, 113: second branch line, 124: main line, 126: branch point, 130 130': cap plate, 140 140': first terminal, 150 150': second terminal, 160 160': vent, 170 170' 172: insulator, 200 200': first layer electrode assembly, 210 210': first electrode tab, 220 220': second electrode tab, 300 300': second layer electrode assembly, 310 310': first electrode tab, 320 320': second electrode tab, 400: three-layer electrode assembly, 410: first electrode tab, 420: second electrode tab, r1,1: basic line resistance of the first collector (110), r1,2 r1,3: additional line resistance of the first collector (110), r2,1: basic line resistance of the second collector (120), r2,2 r2,3: additional line resistance of the second collector (120), V: automobile

Claims

1. Secondary battery case; A plurality of electrode assemblies vertically stacked and built into the case, each having an electrode tab formed thereon; A current collector connected to each electrode tab of the above-described plurality of stacked electrode assemblies; and A secondary battery comprising a cap plate that is joined to the case and on which a terminal connected to the collector is assembled.

2. In the first paragraph, the electrode assembly A secondary battery, one of the coiled, stacked, and Z-stacked electrode assemblies.

3. In the first paragraph, the plurality of electrode assemblies A secondary battery comprising electrode assemblies having the same capacity.

4. In the first paragraph, the plurality of electrode assemblies A secondary battery comprising electrode assemblies having different resistances.

5. A secondary battery in which the resistance of the electrode assembly located in the lower layer is smaller than the resistance of the electrode assembly located in the upper layer in the fourth paragraph.

6. In the first paragraph, the plurality of electrode assemblies A secondary battery comprising electrode assemblies in which one of the number of plates and the number of stacks is different.

7. A secondary battery in claim 6, wherein one of the number of electrode plate turns and the number of stacks of an electrode assembly located in an upper layer among the plurality of electrode assemblies is smaller than one of the number of electrode plate turns and the number of stacks of an electrode assembly located in a lower layer.

8. In the first paragraph, the collector A secondary battery that extends vertically and is connected to electrode tabs formed on the plurality of vertically stacked electrode assemblies.

9. In the first paragraph, the collector A main wire connected to a terminal assembled to the above cap plate; and A secondary battery comprising a plurality of branch lines branched from the above main line and connected to each electrode tab of the plurality of electrode assemblies.

10. A secondary battery further comprising an insulator positioned between the vertically stacked electrode assemblies in the first paragraph.

11. Step of preparing multiple electrode assemblies; A step of manufacturing a case in which the above plurality of electrode assemblies are built-in; A step of manufacturing a current collector connecting the plurality of electrode assemblies and terminals; A step of manufacturing a cap plate on which the above-mentioned collector and terminal are assembled; A secondary battery manufacturing method comprising the step of vertically stacking the plurality of electrode assemblies, connecting the current collector to each electrode assembly, and connecting the cap plate to the terminal.

12. In the 11th paragraph, the step of preparing the plurality of electrode assemblies is A method for manufacturing a secondary battery, comprising the step of manufacturing an electrode assembly of one of a coil type, a stack type, and a Z-stack type.

13. In the 11th paragraph, the step of preparing the plurality of electrode assemblies is A method for manufacturing a secondary battery, comprising a step of manufacturing electrode assemblies having the same capacity.

14. In the 11th paragraph, the step of preparing the plurality of electrode assemblies is A method for manufacturing a secondary battery, comprising a step of manufacturing electrode assemblies having different resistances.

15. A method for manufacturing a secondary battery, wherein the resistance of the electrode assembly located in the lower layer is smaller than the resistance of the electrode assembly located in the upper layer in the 14th paragraph.

16. In the first paragraph, the step of preparing the plurality of electrode assemblies is A method for manufacturing a secondary battery, comprising a step of manufacturing electrode assemblies in which one of the number of plates and the number of stacks is different.

17. A secondary battery manufacturing method in claim 16, wherein one of the number of electrode plate turns and the number of stacks of the electrode assembly located in the upper layer is smaller than one of the number of electrode plate turns and the number of stacks of the electrode assembly located in the lower layer.

18. In the 11th paragraph, the step of manufacturing the collector is A method for manufacturing a secondary battery, comprising the step of manufacturing a vertically extending current collector connected to electrode tabs formed on a plurality of vertically stacked electrode assemblies.

19. In the 11th paragraph, the step of manufacturing the collector is A method for manufacturing a secondary battery, comprising the step of manufacturing a current collector including a main wire connected to a terminal assembled to the cap plate, and a plurality of branch wires branched from the main wire and connected to each electrode tab of the plurality of electrode assemblies.

20. A method for manufacturing a secondary battery, further comprising the step of interposing an insulator between the vertically stacked electrode assemblies in the 11th paragraph.

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