Secondary battery

A secondary battery has a simplified structure of a terminal part to reduce the number of parts, and terminal parts can be directly connected without requiring a separate part (for example, a bus bar) for mutual electrical connection between a battery and another battery. A secondary battery comprises: an electrode assembly, a case for accommodating the electrode assembly; a cap plate coupled to the case; and a terminal part that is electrically connected to the electrode assembly and is extended to penetrate through the cap plate, wherein the terminal part comprises a first area having a first thickness that is electrically connected to the electrode assembly from the inside of the case, and a second area having a second thickness that is thicker than the first thickness and is electrically connected to the first area from the outer side of the case.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a National Phase Patent Application of International Patent Application Number PCT/KR2018/001615, filed on Feb. 6, 2018, which claims priority of Korean Patent Application No. 10-2017-0028523, filed Mar. 6, 2017. The entire contents of both of which are incorporated herein by reference.

TECHNICAL FIELD

Various embodiments of the present invention relate to a secondary battery.

BACKGROUND ART

Unlike a primary battery that is not rechargeable, a secondary battery may be charged and discharged. Low capacity batteries that use single battery cells may be used as power sources for various small-sized portable electronic devices, such as, for example, smart phones and digital cameras. High power batteries that use several tens to several hundreds of battery cells connected to each other in a battery pack may be used as, e.g., driving power sources for electric scooters, hybrid vehicles, or electric vehicles.

Secondary batteries may be manufactured in various types, e.g., prismatic and cylindrical batteries. A secondary battery may be manufactured by accommodating an electrode assembly including a separator (as an insulator) interposed between a positive plate and a negative plate in a case with an electrolyte, and installing a cap plate in the case. Positive and negative electrode terminal parts may be connected to the electrode assembly and may be exposed or protrude to the outside through the cap plate.

Technical Problems to be Solved

The present invention has been made in an effort to solve the problems of the prior art, and the technical problem to be solved is to provide a secondary battery of which the structure of a terminal part is simplified to reduce the number of parts, and terminal parts can be directly connected without requiring a separate part (for example, a bus bar) for mutual electrical connection between a battery and another battery.

Technical Solutions

In accordance with an aspect of the present invention, the above and other objects can be accomplished by providing a secondary battery comprising an electrode assembly; a case for accommodating the electrode assembly; a cap plate coupled to the case; and a terminal part that is electrically connected to the electrode assembly and is extended to penetrate through the cap plate, wherein the terminal part comprises a first area having a first thickness that is electrically connected to the electrode assembly from the inside of the case, and a second area having a second thickness that is thicker than the first thickness and is electrically connected to the first area from the outer side of the case.

The first and second areas may be insulated from the cap plate by an insulating molding resin.

The first and second areas may be electrically connected to each other inside of the cap plate.

The first area may include a first hook area located at its top end, the second area may include a second hook area located at its bottom end, and the first hook area and the second hook area may be coupled to each other.

The first area may be bent in a C- or S-shaped configuration.

The first area may be connected to a single tab or multi-tabs extending from the electrode assembly.

The second area may be bent in parallel with the cap plate.

The second area may be bent in parallel with the cap plate to then be welded to a second area of another secondary battery.

An insulation plate that withstands welding heat may be positioned between the second area and the cap plate.

Advantageous Effects

As described above, various embodiments of the present invention provide a secondary battery, which can reduce the number of parts by simplifying the structure of a terminal part, and can directly connect terminal parts without requiring a separate part (for example, a bus bar) for mutual electrical connection between a battery and another battery.

That is to say, according to various embodiments of the present invention, the terminal part having a plate-shaped first area and a plate-shaped second area is combined with the cap plate, followed by insert-molding using an insulating molding resin, thereby simplifying the structure of the terminal part to reduce the number of parts.

In addition, according to various embodiments of the present invention, the plate-shaped first area of the terminal part is made to have a smaller thickness than the plate-shaped second area, and the relatively thin first area of the terminal part is welded to the electrode assembly, thereby allowing the first area to be easily bent.

In addition, according to various embodiments of the present invention, the plate-shaped terminal part is protruded and extended to the outside of the case, thereby plate-shaped terminal parts of neighboring secondary batteries to be easily welded to each other without a bus bar.

In addition, according to various embodiments of the present invention, in a battery module having terminal parts connected to each other, an insulation plate is further positioned between each of terminal parts and the case, thereby preventing unnecessary electrical short circuits from occurring between the terminal parts and the case.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described in detail.

Various embodiments of the present invention may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments of the disclosure are provided so that this disclosure will be thorough and complete and will convey inventive concepts of the disclosure to those skilled in the art.

In the accompanying drawings, sizes or thicknesses of various components are exaggerated for brevity and clarity. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. In addition, it will be understood that when an element A is referred to as being “connected to” an element B, the element A can be directly connected to the element B or an intervening element C may be present and the element A and the element B are indirectly connected to each other.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise or include” and/or “comprising or including,” when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.

FIGS. 1A to 1Dare a perspective view, a front sectional view, a side sectional view and an enlarged sectional view of a secondary battery100according to various embodiments of the present invention.

As illustrated inFIGS. 1A to 1D, the secondary battery100according to an embodiment of the present invention includes an electrode assembly110, a case120, a cap plate130, a first terminal part140and a second terminal part150.

The electrode assembly110is formed by winding or stacking a stacked structure including a first electrode plate111, a separator113, and a second electrode plate112, which are thin plates or layers. Here, the first electrode plate111may operate as a positive electrode and the second electrode plate112may operate as a negative electrode, and vice versa.

The first electrode plate111may be formed by coating a first electrode active material, such as transition metal oxide, on a first electrode current collector formed of, for example, but not limited to, a metal foil, such as aluminum, and may include a first tab111a(either a single tab or multi-tabs) upwardly extending a predetermined length without the first electrode active material coated thereon. The first tab111abecomes a path for the flow of current between the first electrode plate111and a first terminal part140to be described below.

The second electrode plate112may be formed by coating a second electrode active material, such as graphite or carbon, on a second electrode current collector formed of, for example, but not limited to, a metal foil, such as copper or nickel, and may include a second tab112a(either a single tab or multi-tabs) upwardly extending a predetermined length without the second electrode active material coated thereon. The second tab112abecomes a path for the flow of current between the second electrode plate112and a second terminal part150to be described below.

Polarities of the first electrode plate111and the second electrode plate112may be reversed. In addition, the first and second tabs111aand112amay have a single tab structure in which one of the first and second tabs111aand112ais upwardly extended from the first and second electrode plates111and112or a multi-tab structure in which multiple tabs are upwardly extended from the first and second electrode plates111and112. The multi-tab structure is thicker than the single-tab structure due to overlapping of the tabs.

The separator113, which is positioned between, for example, but not limited to, the first and second electrode plates111and112, may prevent electrical short circuits between the first and second electrode plates111and112, and may allow lithium ions to move. The separator113may include polyethylene, polypropylene, or a combined film of polypropylene and polyethylene. In addition, when an organic solid electrolyte, an organic-inorganic hybrid solid electrolyte, or an inorganic solid electrolyte is positioned between the first electrode plate111and the second electrode plate112, the separator113may not be provided.

The electrode assembly110may be received in the case120with, for example, but not limited to, an electrolyte solution. The electrolyte solution may include a lithium salt, such as LiPF6or LiBF4dissolved in an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). In addition, the electrolyte solution may be in a liquid, solid or gel phase.

The case120may be made of, for example, but not limited to, a conductive metal, such as aluminum, an aluminum alloy, steel, a steel alloy, nickel plated steel, or a nickel plated steel alloy, and may have an approximately hexahedral shape having an opening through which some portions of the electrode assembly110, the first terminal part140and the second terminal part150are inserted and placed. More specifically, the case120includes a pair of long side regions121aand121bhaving relatively areas, a pair of short side regions122aand122bconnecting the pair of long side regions121aand121band having relatively areas, and a bottom region123connecting the long side regions121aand121band the short side regions122aand122b. Here, the first tab111aof the electrode assembly110is extended a predetermined length in a direction opposite to the bottom region123(that is, in an upward direction), and the second tab111bis also extended a predetermined length in the direction opposite to the bottom region123(that is, in the upward direction). In addition, the first terminal part140may be located in vicinity of the short side region122aof the case120, and the second terminal part150may be located in vicinity of the short side region122bof the case120.

Meanwhile, the interior surface of the case120may be subjected to insulation treatment such that it is electrically isolated from the electrode assembly110, the first terminal part140and the second terminal part150. Of course, the electrode assembly110, the first terminal part140and the second terminal part150may be positioned inside of the case120while being received in an insulation bag (not shown).

The cap plate130may be coupled to the opened top portion of the case120by, for example, laser welding, but embodiments of the present invention are not limited thereto. Therefore, the case120and the cap plate130are electrically connected to each other. In addition, the cap plate130and the case120may be made of the same material. Here, the cap plate130and the first terminal part140may be electrically connected to each other. Accordingly, the cap plate130may have the same polarity with the first terminal part140. Therefore, the case120and the cap plate130may have the same polarity. Conversely, the cap plate130and the second terminal part150may be electrically connected to each other. Accordingly, the cap plate130and the case120may have the same polarity with the second terminal part150. Of course, the first terminal part140and the second terminal part150may not be electrically connected to the cap plate130at the same time.

The cap plate130includes a first terminal hole131through which the first terminal part140passes, and a second terminal hole132through which the second terminal part150passes. In addition, the cap plate130may further include an injection hole133afor supplying the electrolyte solution and a plug133bcoupled to the injection hole133a. In addition, the cap plate130may include a vent hole134aconfigured to allow internal gases to be easily discharged to the outside when the internal pressure of the case120is greater than a reference pressure, and a safety vent134bcoupled to the vent hole134ahaving a relatively small thickness.

The first terminal part140is electrically connected to the first tab111aof the electrode assembly110and includes a first area141and a second area142upwardly extended a predetermined length while passing through the first terminal hole131of the cap plate130. In addition, the first terminal part140further includes an insulating molding resin143in the first terminal hole131and on the surface of the cap plate130around the first terminal hole131.

The first area141is substantially plate-shaped and is generally located inside of the case120to be electrically connected to the first tab111aof the electrode assembly110. In addition, the first area141may be bent in a roughly C- or S-shaped configuration inside of the case120, which is an upper portion of the electrode assembly110. In addition, a top end of the first area141is connected to a bottom end of the second area142. Here, the first area141may be mainly bent in a direction ranging from the first long side region121ato the second long side region121bof the case120or from the second long side region121bto the first long side region121a. In addition, as the first area141is bent, the first tab111awelded to the first area141is also bent in a predetermined shape.

In addition, the second area142is substantially plate-shaped and is generally located outside of the case120to upwardly extend a predetermined length. The second area142may be directly electrically connected to a first terminal part or a second terminal part of another secondary battery in a later stage, which will further be described below.

In addition, the first area141may have a first thickness, and the second area142may have a second thickness that is larger than the first thickness. That is to say, since the first area141needs to be bent in a predetermined shape (for example, a C-shaped configuration, an S-shaped configuration, etc.) when the cap plate130is coupled to the case120after being electrically connected (e.g., welded) to the first tab111a, the first thickness of the first area141may be smaller than the second thickness of the second area142(Refer toFIG. 1C.). However, since the first area141is thicker than the first tab111a, the first tab111ais easily welded to the first area141. That is to say, in the present invention, the thickness of the first area141may be larger than the thickness of the first tab111a, the thickness of the second area142may be larger than the thickness of the first area141. Here, the first tab111aand the first area141have ductility so as to be easily bent during the manufacture process, and the second area142has rigidity so as to be scarcely bent during the manufacture process. However, the second area142may be mechanically bent without being damaged when being welded to a second area of another battery.

In addition, the first area141includes a first hook area141alocated at its top end, the second area142includes a second hook area142alocated at its bottom end, and the first and second hook areas141aand142amay be coupled to each other. Here, the first and second hook areas141aand142acoupled to each other may be generally located inside of a first through-hole131of the cap plate130. That is to say, the first and second hook areas141aand142aare covered by an insulating molding resin143(Refer toFIG. 1C.).

Here, the first and second hook areas141aand142amay further be welded to each other by laser welding, ultrasonic welding and/or resistance welding after being coupled/connected/compressed to each other. In addition, the first area141and the second area142may be coupled/connected/compressed/welded to each other without the first and second hook areas141aand142aafter the top end of the first area141and the bottom end of the second area142are positioned to overlap each other.

Meanwhile, the first and second areas141and142may be made from the same material with the first tab111a. For example, if the first tab111ais made from aluminum or an aluminum alloy, the first and second areas141and142may also be made from aluminum or an aluminum alloy. In addition, if the first tab111ais made from copper, a copper alloy, nickel or a nickel alloy, the first and second areas141and142may also be made from copper, a copper alloy, nickel or a nickel alloy. As such, since the first and second areas141and142(specifically, the first area141) and the first tab111aare made from the same material, the first area141may be easily welded to the first tab111a.

In addition, when the first tab111ais made from copper, a copper alloy, nickel or a nickel alloy, the first area141may be made from copper, a copper alloy, nickel or a nickel alloy, and the second area142may be made from aluminum or an aluminum alloy. However, even if the first area141is copper- or nickel-based, since the second area142is aluminum-based, it can be easily welded to a terminal (e.g., an aluminum terminal, etc.) of another battery.

The insulating molding resin143is located in the first terminal hole131and covers the first terminal part140, that is, the first and second areas141and142or the first and second hook areas141aand142aof the first and second areas141and142. In addition, the insulating molding resin143is also located to a constant thickness on top and bottom surfaces of the cap plate130near the first terminal hole131.

Here, the insulating molding resin143is preferably made from a material that is not reactive with an electrolyte and is suitable to a molding process. More specifically, the insulating molding resin143may be one selected from the group consisting of a fluorine resin, a polyethylene (PE) resin, a polypropylene (PP) resin, an ethylene propylene diene monomer (EPDM) resin, and equivalents thereof, but aspects of the present invention are not limited thereto.

The second terminal part150is electrically connected to the second tab112aof the electrode assembly110and includes a first area151and a second area152upwardly extended a predetermined length while passing through the second terminal hole132of the cap plate130. In addition, the second terminal part150further includes an insulating molding resin153located in the second terminal hole132and on the surface of the cap plate130around the second terminal hole132. The configuration, shape and features of the first terminal part140can be commonly applied to those of the second terminal part150, additional explanations of the second terminal part150will not be given.

FIGS. 2A to 2Care schematic views illustrating a manufacturing method of a terminal part according to various embodiments of the present invention.

As illustrated inFIG. 2A. a first mold10having a first cavity11and a second mold20having a second cavity21are prepared. Here, a gate12having a small width for injection of a high-temperature molten insulating molding resin143is provided in the first cavity11of the first mold10. In addition, the cap plate130having the terminal hole131and the terminal part140coupled to the terminal hole131, that is, the first area141and the second area142, are positioned together between the first mold10and the second mold20.

As illustrated inFIG. 2B, the high-temperature molten insulating molding resin143is injected to the first cavity11and the second cavity21with a high pressure through the gate12. Here, since the first cavity11and the second cavity21are connected to each other, the insulating molding resin143injected into the first cavity11flows to the second cavity21. Next, if temperatures of the first and second molds10and20are lowered, the insulating molding resin143is hardened. Therefore, the insulating molding resin143is applied to the top and bottom surfaces of the cap plate130near the terminal hole131as well as to the terminal hole131of the cap plate130to a constant thickness.

As illustrated inFIG. 2C, the cap plate130, the first terminal part140and the second terminal part150are extracted from the first mold10and the second mold20to obtain the cap plate130, the first terminal part140and the second terminal part150, which are integrated with one another. That is to say, according to an embodiment of the present invention, the cap plate130, the first terminal part140and the second terminal part150are integrated by an insert-molding process using the insulating molding resin143, thereby simplifying a secondary battery assembling process. In other words, since the number of components constituting the first terminal part140and the second terminal part150is reduced, the secondary battery assembling process is simplified.

FIGS. 3A to 3Care schematic views illustrating an assembling method of a secondary battery module1000according to various embodiments of the present invention.

As illustrated inFIG. 3A, multiple secondary batteries100are first arranged in a horizontal direction. Here, first and second terminal parts140and150are extended from each of the secondary batteries100in an upwardly perpendicular direction with respect to the cap plate130. A zig plate201, which is not welded during welding, is positioned at a boundary region of the secondary batteries.

As illustrated inFIG. 3B, if first and second terminal parts140and150that are upwardly extended toward an upper portion of the cap plate130are positioned to face each other, some portions of the first and second terminal parts140and150are overlapped with each other. Here, the first terminal part140of a first-side secondary battery100and the second terminal part150of a second-side secondary battery100adjacent to the first-side secondary battery100are overlapped with each other while facing each other. The first terminal part140of the first-side secondary battery100and the second terminal part150of the second-side secondary battery100, which are overlapped with each other, are subjected to, for example, but not limited to, laser welding, thereby allowing the adjacent secondary batteries100to be electrically connected to each other. Here, the welded first and second terminal parts140and150may have different polarities or the same polarity. After the welding, the jig plate201may be removed.

Finally, as illustrated inFIG. 3C, the terminal parts140and150of neighboring secondary batteries100are directly electrically connected to each other without requiring a bus bar, thereby providing the secondary battery module1000.

FIGS. 4A to 4Care schematic views illustrating an assembling method of a secondary battery module2000according to various embodiments of the present invention.

As illustrated inFIG. 4A, multiple secondary batteries100are first arranged in a horizontal direction. Here, first and second terminal parts140and150are extended from each of the secondary batteries100in an upwardly perpendicular direction with respect to the cap plate130. An insulation plate202, which is not welded during welding, is positioned at an upper region (a cap plate) of each secondary battery100.

As illustrated inFIG. 4B, the first and second terminal parts140and150upwardly extended from the cap plate130are bent in a substantially horizontal direction. Here, the first terminal part140of a first-side secondary battery100and the second terminal part150of a second-side secondary battery100adjacent to the first-side secondary battery100are overlapped with each other. The first terminal part140of the first-side secondary battery100and the second terminal part150of the second-side secondary battery100, which are overlapped with each other, are subjected to, for example, but not limited to, laser welding, thereby allowing the adjacent secondary batteries100to be electrically connected to each other. Here, the welded first and second terminal parts140and150may have different polarities or the same polarity.

Even after the welding, the insulation plate202may not be removed but may remain in the upper regions of the secondary batteries100. Therefore, unnecessary electrical short circuits that may occur between each of the first and second terminal parts140and150and the cap plate130can be prevented.

As illustrated inFIG. 4C, the first and second terminal parts140and150of neighboring secondary batteries100are directly electrically connected to each other without requiring a bus bar, thereby providing the secondary battery module2000. Here, the insulation plate202may remain on each of the secondary batteries100and may include a through-hole203located on a region corresponding to a safety vent of the secondary battery100.

Although the foregoing embodiments have been described to practice the secondary battery of the present invention, these embodiments are set forth for illustrative purposes and do not serve to limit the invention. Those skilled in the art will readily appreciate that many modifications and variations can be made, without departing from the spirit and scope of the invention as defined in the appended claims, and such modifications and variations are encompassed within the scope and spirit of the present invention.