Patent Application
20250087802
The present invention relates to a stack-type electrode assembly, and to a technique for improving the practical capacity of a stack-type electrode assembly by shortening the length of a foil tab of a stack-type electrode assembly, thereby reducing the area occupied by a non-coated part.
Unlike primary batteries, secondary batteries can be recharged, and they have been heavily researched and developed in recent years due to their potential for miniaturization and large capacity. The demand for secondary batteries as an energy source is increasing rapidly due to the technological development and increasing demand for mobile devices, electric vehicles, and energy storage systems, which are emerging in response to the need for environmental protection.
Secondary batteries are categorized into coin-type cells, cylindrical cells, prismatic cells, and pouch-type cells based on the shape of the cell case. In a secondary battery, an electrode assembly mounted inside the battery case is a charge and dischargeable power generator consisting of a laminated structure of electrodes and separators.
Electrode assemblies can be roughly categorized into Jellyroll type, which is wound by interposing a separator between a positive electrode and negative electrode of an active material-coated sheet, Stack-type in which a plurality of positive electrodes and negative electrodes is sequentially stacked with a separator interposed therebetween, and Stack & Folding type in which stack-type unit cells are wound with a long separator film.
Among the various types of electrode assemblies, the stack-type electrode assembly consists of a number of unit cells stacked in a stack structure, with separators placed between the positive electrodes and negative electrodes, and each unit cell is provided with its own foil tab, including a positive electrode tab and a negative electrode tab. The foil tabs are formed by performing a punching process on a non-coated part of the positive electrode and negative electrode, where an active material is not applied. These foil tabs serve as the entrance and exit for electrical connections to the electrode assembly, and a plurality of foil tabs are welded to a current collector and tied together as one.
However, as the capacity of secondary batteries increases to medium and large sizes, the number of unit cells stacked in the stack-type electrode assembly also increases. As the number of stacked unit cells increases, the number of foil tabs increases accordingly. The more foil tabs there are, the more difficult it becomes to weld them to the current collector, and the foil tabs are made longer to facilitate easier welding.
The lengthening of the foil tabs means an increase in the width of the non-coated part in both the positive electrode and negative electrode. As the non-coated part without the active material increase, the actual capacity based on an electrode assembly of the same size decreases.
The background description provided herein is for the purpose of generally presenting context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art, or suggestions of the prior art, by inclusion in this section.
The present disclosure provides a solution for effective welding of a plurality of foil tabs to a current collector without increasing the length of the foil tabs, in line with the trend towards medium and large capacities of secondary batteries.
However, the technical problems to be solved by the present disclosure are not limited to the above-described problem, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.
The present disclosure provides an electrode assembly which may include a stack-type electrode assembly; a plurality of positive electrode tabs located at a first end of the stack-type electrode assembly in a width direction; and a plurality of negative electrode tabs located at a second end of the stack-type electrode assembly in the width direction; and a positive electrode current collector and a negative electrode current collector electrically connected to the plurality of positive electrode tabs and to the plurality of negative electrode tabs, respectively, wherein: an end of each of the plurality of positive electrode tabs and an end of each of the plurality of negative electrode tabs are individually bonded to the positive electrode current collector and to the negative electrode current collector, respectively.
An end of each of the positive electrode tabs and an end of each of the negative electrode tabs may include a bending portion, and the bending portion of each of the positive electrode tabs and the bending portion of each of the negative electrode tabs may be individually bonded to the positive electrode current collector and the negative electrode current collector, respectively.
Here, each bending portion of the positive electrode tabs and each bending portion of the negative electrode tabs may be directly bonded to a facing surface of the positive electrode current collector and a facing surface of the negative electrode current collector, respectively.
In an exemplary embodiment of the present disclosure, the positive electrode tabs may be arranged in a row at a substantially equal height with respect to the stack-type electrode assembly; and the negative electrode tabs may be arranged in a row at a substantially equal height with respect to the stack-type electrode assembly.
In an exemplary embodiment of the present invention, the positive electrode tabs may form a plurality of positive tab groups, each positive tab group may be arranged in a row at a different height with respect to the stack-type electrode assembly; and the negative electrode tabs may form a plurality of negative tab groups, each negative tab group may be arranged in a row at a different height with respect to the stack-type electrode assembly.
For example, the stack-type electrode assembly may include a plurality of unit cells arranged in a thickness direction; each positive tab group of the plurality of positive tab groups may comprise the positive electrode tabs of a plurality of adjacent unit cells of the stack-type electrode assembly; and each negative tab group of the plurality of negative tab groups may comprise the negative electrode tabs of a plurality of adjacent unit cells of the stack-type electrode assembly.
In addition, the positive electrode current collector may include a plurality of positive branch current collectors, each positive branch current collector may correspond to one of the positive tab groups in the plurality of positive tab groups; and the negative electrode current collector may include a plurality of negative branch current collectors, each negative branch current collector may correspond to one of the negative tab groups in the plurality of negative tab groups.
In certain embodiments, the plurality of positive branch current collectors may be arranged in parallel with respect to the thickness direction of the stack-type electrode assembly, each of the positive branch current collectors may have extend in a different height according to a height of one of the positive tab groups in the plurality of positive tab groups; and the plurality of negative branch current collectors may be arranged in parallel with respect to the thickness direction of the stack-type electrode assembly, each of the negative branch current collectors may extend in a different height according to a height of one of the negative tab groups in the plurality of negative tab groups.
In certain cases, each positive tab group of the plurality of positive tab groups may comprise at least one non-contiguous pair of positive electrode tabs; and each negative tab group of the plurality of negative tab groups may comprise at least one non-contiguous pair of negative electrode tabs.
In certain cases, the positive electrode tabs of adjacent unit cells of the stack-type electrode assembly may be arranged in a row at a different height with respect to the stack-type electrode assembly; and the negative electrode tabs of adjacent unit cells of the stack-type electrode assembly may be arranged in a row at a different height with respect to the stack-type electrode assembly.
In addition, each of the plurality of positive branch current collectors may include a first portion extending in the thickness direction of the stack-type electrode assembly, wherein the first portions of each of the plurality of positive branch current collectors may be arranged in parallel with respect to a height direction of the stack-type electrode assembly; each of the plurality of positive branch current collectors may include a second portion extending in the height direction of the stack-type electrode assembly according to a height of one of the positive tab groups in the plurality of plurality of positive tab groups; each of the plurality of negative branch current collectors may include a first portion extending in the thickness direction of the stack-type electrode assembly, wherein the first portions of each of the plurality of negative branch current collectors may be arranged in parallel with respect to the height direction of the stack-type electrode assembly; and each of the plurality of negative branch current collectors may include a second portion extending in the height direction of the stack-type electrode assembly according to a height of one of the negative tab groups in the plurality of plurality of negative tab groups.
Meanwhile, the present disclosure may provide a prismatic secondary battery including: a case; an electrode assembly, such as those disclosed herein, stored inside the case; a cap plate coupled to the case, the cap plate including a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal are electrically connected to the positive electrode current collector and the negative electrode current collector of the electrode assembly, respectively; and an electrolyte inside the case.
A stack-type electrode assembly of the present disclosure with the aforementioned configuration not only resolves the issue of the lengthening of foil tabs that occurs when a plurality of foil tabs are tack-welded and then welded to the current collector, as in conventional methods, by individually bonding each positive and negative electrode tab to the positive electrode current collector and negative electrode current collector, but it also improves the electrical conductivity of the stack-type electrode assembly.
In addition, in the stack-type electrode assembly according to the present disclosure, the positive tabs and negative tabs each have a bending portion at their ends, and these bending portions are individually bonded to the positive electrode current collector and negative electrode current collector. Through the bending portion, sufficient welding area at the ends of the foil tabs may be secured, thereby preventing issues such as the foil tabs from shorting in the current collector due to insufficient welding strength.
However, the technical effects that can be obtained through this disclosure are not limited to those described above. Other effects not mentioned here will be clearly understood by those skilled in the art from the description detailed below.
The following drawings accompanying this specification illustrate preferred exemplary embodiments of the present disclosure and are intended to serve as a further understanding of the technical ideas of the present disclosure in conjunction with the detailed description of the disclosure that follows, so the present disclosure is not to be construed as limited to what is shown in such drawings.
The present disclosure may have various modifications and various examples, and specific examples are illustrated in the drawings and described in detail in the description.
However, it should be understood that the present disclosure is not limited to specific embodiments, and includes all modifications, equivalents or alternatives within the spirit and technical scope of the present disclosure.
The terms “comprise,” “include” and “have” are used herein to designate the presence of characteristics, numbers, steps, actions, components or members described in the specification or a combination thereof, and it should be understood that the possibility of the presence or addition of one or more other characteristics, numbers, steps, actions, components, members or a combination thereof is not excluded in advance.
In addition, when a part of a layer, a film, a region or a plate is disposed “on” another part, this includes not only a case in which one part is disposed “directly on” another part, but a case in which a third part is interposed there between. In contrast, when a part of a layer, a film, a region or a plate is disposed “under” another part, this includes not only a case in which one part is disposed “directly under” another part, but a case in which a third part is interposed there between. In addition, in this application, “on” may include not only a case of disposed on an upper part but also a case of disposed on a lower part.
The present disclosure provides an electrode assembly that includes a stack-type electrode assembly, and a positive electrode current collector and a negative electrode current collector.
The stack-type electrode assembly is a plurality of unit cells stacked in a stack structure with a separator interposed between the positive electrode and negative electrode, with a plurality of positive electrode tabs and a plurality of negative electrode tabs formed at each end in the width direction. That is, the positive electrode tabs and negative electrode tabs are separated from each other on the sides of the stack-type electrode assembly.
The positive electrode current collector and the negative electrode current collector are each a component of conductive material to which a plurality of positive electrode tabs and a plurality of negative electrode tabs are electrically connected. By having both a plurality of positive electrode tabs and a plurality of negative electrode tabs connected to the positive electrode current collector and the negative electrode current collector, respectively, the stack-type electrode assembly can be stored in the case of a prismatic secondary battery and wiring to the positive and negative electrode terminals is facilitated.
In the present disclosure, the ends of the positive electrode tabs and negative electrode tabs are individually bonded to the positive electrode current collector and negative electrode current collector, respectively. As each positive electrode tab and negative electrode tab are independently bonded to the positive electrode current collector and negative electrode current collector, it not only solves the problem of the foil tabs lengthening due to tack welding of a plurality of foil tabs followed by re-welding to the current collector, as in conventional methods, but also enables performance improvements such as electrical conductivity performance in the stack-type electrode assembly, for example, increased rated current or reduced resistance, and the like.
In addition, in the present disclosure, the positive electrode tabs and negative electrode tabs are each provided with a bending portions at their ends, and the bending portions of the positive electrode tabs and negative electrode tabs are individually bonded to the positive electrode current collectors and negative electrode current collectors, respectively. Through the bending portion, sufficient welding area at the ends of the foil tabs may be secured, thereby preventing issues such as the foil tabs from shorting in the current collector due to insufficient welding strength.
Hereinafter, a detailed description will be given of specific embodiments of the secondary battery of the present disclosure with reference to the attached drawings. For reference, the relative positions specified in the directions of front and back, up and down, and left and right used in the following description are intended to aid in understanding the disclosure, and unless specially defined, are based on the directions shown in the drawings.
The stack-type electrode assembly 1100 is a plurality of unit cells stacked in sequence along one direction (thickness direction) with a separator interposed between the positive electrode and negative electrode, with a plurality of positive electrode tabs 1132 and a plurality of negative electrode tabs 1134 formed at each end of the width direction W.
The positive electrode tabs 1132 and negative electrode tabs 1134 are collectively referred to as foil tabs 1130, and are formed by performing a punching process on a non-coated part 1120, which has no active material applied at the positive electrode and negative electrode, respectively. In other words, the illustrated stack-type electrode assembly 1100 has a coated part 1110 to which an active material is applied in the center part, and non-coated parts 1120 are arranged on both sides of the coated part 1110, and accordingly, the positive electrode tabs 1132 and negative electrode tabs 1134, which are punched on the non-coated parts 1120, are of different polarity and separately arranged on both sides of the stack-type electrode assembly 1100.
Conventionally, a plurality of foil tabs 1130 (positive electrode tabs and negative electrode tabs) provided on the stack-type electrode assembly 1100 are tack welded to structurally and electrically interconnect and then re-welded to the current collector 1200, thereby requiring that the foil tabs 1130 be sufficiently long as the distance from the stack-type electrode assembly 1100 to the current collector 1200 increases.
In comparison, the electrode assembly 1000 of the present disclosure minimizes the distance from the stack-type electrode assembly 1100 to the current collector 1200 as each of the positive electrode tabs 1132 and negative electrode tabs 1134 are independently welded to the positive electrode current collector 1210 and negative electrode current collector 1220, thereby increasing the substantial capacity based on the same size stack-type electrode assembly 1100 by shortening the length of the foil tabs 1130 in which a non-coated part 1120 without an active material is processed. In addition, since the individual foil tabs 1130 are welded directly to the current collector 1200, a sufficient conduction area can be secured to carry a high current, and thus improved conduction performance, such as an increase in rated current and a decrease in resistance, can be obtained.
Also, referring to
As such, by forming the bending portion 1140 at their respective ends, the positive electrode tab 1132 and negative electrode tab 1134 can provide sufficient welding area at the ends of the foil tab 1130, thereby effectively preventing the foil tab 1130 from shorting out from the current collector 1200 due to insufficient welding strength.
And, in the first embodiment of the present disclosure, the positive electrode tabs 1132 and negative electrode tabs 1134 may be formed in a row at the same height relative to the stack-type electrode assembly 1100. Correspondingly, the positive electrode current collector 1210 and the cathode collector 1220 have a width approximately corresponding to the thickness of the stack-type electrode assembly 1100, and the respective bending portions 1140 of the positive electrode tab 1132 and the negative electrode tab 1134 are welded in line to the positive electrode current collector 1210 and the negative electrode current collector 1220, respectively.
In the first embodiment, where both the plurality of positive electrode tabs 1132 and negative electrode tabs 1134 are welded in line with respect to the current collector 1200, the number of foil tabs 1130 that can be welded to the current collector 1200 may be increased if the number of stacked unit cells is increased to increase the thickness of the stack-type electrode assembly 1100. Here, the number of weldable foil tabs 1130 on the current collector 1200 can be understood to include not only the limit of foil tabs 1130 that are physically non-weldable, but also practical difficulties in welding, such as difficulty in welding due to limited welding space, or difficulty in obtaining a uniform welding quality.
The second embodiment of the present disclosure is designed to improve several aspects of welding quality and welding management by dividing the plurality of positive electrode tabs 1132 and negative electrode tabs 1134 into several tab groups 1150. The second embodiment can be broken down into the specific examples of
In the second embodiment shown in
Correspondingly, the positive electrode current collector 1210 and negative electrode current collector 1220 can each have a number of branch current collectors 1230 corresponding to the plurality of tab groups 1150. A branch current collector 1230 refers to a partial current collector that is branched off from a single current collector as a stem, with each branch current collector 1230 having a different length corresponding to an up or down arrangement of the tab groups 1150 and arranged side-by-side along the height direction H of the stack-type electrode assembly 1100. The branched branch current collectors 1230 further facilitate welding operations for each tab group 1150.
And, in the second embodiment shown in
In a single tab group 1150, the distance between the positive electrode tabs 1132 and the negative electrode tabs 1134 may be as wide as the spacing of the skipped unit cells, which is advantageous for maintaining and improving the welding quality by securing more welding space on the current collector 1200 as the distance between the electrode tabs increases.
In addition, the positive electrode current collector 1210 and negative electrode current collector 1220 each have a number of branch current collectors 1230 corresponding to the plurality of tab groups 1150, and in the embodiment of
Meanwhile, the present disclosure may provide a prismatic secondary battery 10 including the electrode assembly 1000 according to the first embodiment or the second embodiment, and an example of such a prismatic secondary battery 10 is shown in
Referring to
Thus, the prismatic secondary battery 10 of
Various principles have been described in more detail above with reference to the drawings and embodiments. However, it is to be understood that the configurations shown in the drawings or embodiments described herein are only particular embodiments and do not represent all of the technical ideas of the disclosure, and that there may be various equivalents and modifications that may replace them at the time of filing the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0100270 | Aug 2022 | KR | national |
This application is a National Phase entry pursuant to 35 U.S.C. § 371 of International Application No. PCT/KR2023/011809 filed on Aug. 10, 2023, which claims priority to and the benefit of Korean Patent Application No. KR 10-2022-0100270, filed on Aug. 11, 2022. The contents of the above-identified applications are herein incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2023/011809 | 8/10/2023 | WO |
