Rechargeable battery including terminal portion having auxiliary plate for reducing current flow along short circuit current path

A rechargeable battery is provided. The rechargeable battery includes a case, an electrode assembly in the case, a cap plate sealing an opening of the case, and a terminal portion attached to the cap plate. The terminal portion includes a terminal plate on the cap plate and electrically connected to the electrode assembly, and an auxiliary plate electrically connecting the cap plate to the terminal plate. The auxiliary plate has a plurality of openings for reducing a current flow along a short circuit current path.

BACKGROUND

Aspects of embodiments of the present invention relate generally to a rechargeable battery.

2. Description of the Related Art

A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter makes only the irreversible conversion of chemical to electrical energy. The low-capacity rechargeable battery is used as the power supply for small electronic devices, such as cellular phones, notebook computers, and camcorders, while the high-capacity rechargeable battery is used as the power supply for driving motors in hybrid vehicles and the like.

A high-power rechargeable battery using a non-aqueous electrolyte with a high energy density has been recently developed. For example, the high-power rechargeable battery is constructed with a plurality of rechargeable cells coupled to each other in series such that it can be used as the power supply for driving motors in electric vehicles requiring high power. The rechargeable battery may, for instance, have a cylindrical shape or a prismatic shape.

An electrode assembly of the rechargeable battery may be received in a case formed in the shape of a cylinder or a prism such that the electrode assembly can be prevented from being damaged due to foreign materials. However, when a conductive foreign material (e.g., a conductive nail) penetrates the case and the electrode assembly, a negative electrode and a positive electrode that form the electrode assembly may be short-circuited.

In addition, when the rechargeable battery has a structure including a case formed of a conductive material and a terminal electrically connected to the case, a short-circuit may occur between the negative electrode and the positive electrode due to the conductive foreign material penetrating the electrode assembly through the case. As a result, a current path may be formed between the conductive foreign material, the case, and the terminal.

Accordingly, when a current discharged to the outside of the case through the terminal of the electrode assembly returns to the conductive foreign material penetrating the electrode assembly in the case, an excessive amount of current flows to the conductive foreign material such that heat or arcing generated in the conductive foreign material may cause damage to the electrode assembly or battery environment.

SUMMARY

Aspects of embodiment of the present invention are generally directed toward a rechargeable battery and more particularly, to a rechargeable battery having an improved terminal portion. Further aspects are directed toward a rechargeable battery including a structure that can lessen or minimize the amount of discharged current returning to the rechargeable battery by penetration of a conductive foreign material. Still further aspects are directed toward a rechargeable battery including an auxiliary plate along a short circuit current path, the auxiliary plate having a plurality of openings (for example, numerous small holes or grooves, such as dozens or hundreds of openings) for allowing the auxiliary plate to consume significant amounts of short circuit current (i.e., reduce the current flow along the short circuit current path).

In an exemplary embodiment of the present invention, a rechargeable battery is provided. The rechargeable battery includes a case, an electrode assembly in the case, a cap plate sealing an opening of the case, and a terminal portion attached to the cap plate. The terminal portion includes a terminal plate on the cap plate and electrically connected to the electrode assembly, and an auxiliary plate electrically connecting the cap plate to the terminal plate. The auxiliary plate has a plurality of openings for reducing a current flow along a short circuit current path.

The plurality of openings may be holes in the auxiliary plate.

The auxiliary plate may have a mesh structure.

The mesh structure may include a plurality of mesh strands defining the holes.

The mesh strands may have a uniform thickness.

The terminal portion may further include a reinforcement plate for reinforcing a mechanical strength of the mesh structure.

The reinforcement plate may be configured to dissipate heat generated in the mesh structure.

The reinforcement plate may be between the auxiliary plate and the terminal plate.

The reinforcement plate may mate flush with the terminal plate.

The plurality of openings may be grooves in the auxiliary plate.

Each of the grooves may have a quadrilateral shape on a surface of the auxiliary plate.

The grooves may include top portions and recessed portions. The top portions may form a level mating surface facing the terminal plate.

The auxiliary plate may mate flush with the terminal plate.

The auxiliary plate may mate flush with the cap plate.

The auxiliary plate may be electrically connected to the case.

The short circuit current path may be between the case and the electrode assembly.

A surface of the auxiliary plate facing the terminal plate may be at least as large as a surface of the terminal plate facing the auxiliary plate.

The plurality of openings may include at least 50 openings.

The terminal plate may have a level mating surface facing the cap plate.

The auxiliary plate may have a level mating surface facing the cap plate.

The terminal plate may be only electrically connected to the cap plate via the auxiliary plate.

The terminal plate may be a positive terminal plate and electrically connected to the case.

The terminal portion may further include a terminal member electrically connecting the terminal plate to the electrode assembly, and a terminal gasket electrically insulating the terminal member from the cap plate except via the terminal plate.

A rechargeable battery according to an exemplary embodiment includes a case, an electrode assembly received in the case, a cap plate sealing an opening of the case, and a terminal portion provided in the cap plate to be electrically connected to the electrode assembly. The terminal portion includes an auxiliary plate provided on the cap plate and formed of a conductive material, and a terminal plate combined with the auxiliary plate. A plurality of holes is formed in at least a part of the auxiliary plate.

According to an exemplary embodiment, the amount of discharged current from the rechargeable battery returning to the conductive foreign material penetrating the rechargeable battery can be reduced, and therefore damage to the rechargeable battery or surroundings due to heat or arcing can be reduced or prevented.

DETAILED DESCRIPTION

In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. It will be understood that one layer or element that is said to be “on” another layer or base may be directly on the other layer or base, or may have another layer or layers interposed therebetween. It will also be understood that one layer that is said to be “under” another layer may be directly under the other layer or have at least one other layer interposed therebetween. Further, it will be understood that one layer that is said to be “between” two other layers may be the only layer between the two layers or may have at least one or another layer inserted therebetween. In addition, like reference numerals designate like elements throughout the present specification and drawings.

FIG. 1is a perspective view of a rechargeable battery100penetrated by a conductive foreign material90according to a first exemplary embodiment of the present invention.FIG. 2is a cross-sectional view ofFIG. 1, taken along the line II-II.

Referring toFIG. 1andFIG. 2, the rechargeable battery100includes an electrode assembly10, a case26in which the electrode assembly10is inserted, first and second terminal portions30and40electrically connected to the electrode assembly10, a cap plate20coupled to an opening formed in the case26, and first and second lower insulation members60and80provided in the case26. Here, the electrode assembly10is formed by spirally winding a first electrode11and a second electrode12, interposing a separator13therebetween.

The rechargeable battery100is exemplarily illustrated as an angular lithium ion rechargeable battery. However, the present invention is not limited thereto, and the present invention may be applied to a lithium polymer battery and the like. In addition, the first electrode11may be formed as a negative electrode and the second electrode12may be formed as a positive electrode, or the first electrode11may be formed as a positive electrode and the second electrode12may be formed as a negative electrode. However, for better comprehension and ease of description, the first and second electrodes11and12will be described instead of the negative and positive electrodes.

The electrode assembly10may be formed in the shape of a jellyroll by spirally winding the first electrode11and the second electrode12, together with the separator13. Each of the first electrode11and the second electrode12may include a current collector formed of thin film metal foil and an active material coated on the surface of the current collector. In addition, the first electrode11and the second electrode12may be partitioned into a coated region where the current collector is coated with the active material and first and second uncoated regions11aand12awhere the current collector is not coated with the active material. The coated region forms most of the first and second electrodes11and12in the electrode assembly10, and the first and the second electrode uncoated regions11aand12amay be respectively disposed in a jellyroll state on both ends of the coated regions.

However, the present invention is not limited thereto, and the electrode assembly10may have a structure in which first and second electrodes11and12formed of a plurality of sheets are stacked, interposing a separator13therebetween.

A first terminal portion30is electrically connected to the first electrode uncoated region11aof the electrode assembly10through a first current collecting member50, and a second terminal portion40is electrically connected (e.g., along an electrical power current path) to the second electrode uncoated region12athrough a second current collecting member70.

The case26may be formed in the shape of a cuboid. An opening is formed on one side of the case26. However, the present invention is not limited thereto, and the case may have various shapes such as a cylindrical shape, a pouch shape, and the like.

A cap plate20may be formed of a thin plate, and may be coupled to the opening of the case26to seal the opening. In addition, an electrolyte injection opening21for injection of an electrolyte solution into the sealed case26may be formed in the cap plate20. The electrolyte injection opening21may be sealed by a sealing cap22after injection of the electrolyte solution. Further, a vent hole23where a vent plate24is formed may be formed in the cap plate20. The vent plate24may be ruptured when an internal pressure of the sealed case26is higher than a set pressure (for example, a predetermined pressure).

The first and second terminal portions30and40may respectively include first and second terminal members (for example, first and second rivets31and41), first and second terminal plates32and42, first and second terminal connection pillars33and43, first and second gaskets (or terminal gaskets)34and44, and a terminal insulation members35and an auxiliary plate45.

In further detail, the first and second rivets31and41may respectively include first and second pillar portions31aand41a, first and second flange portions31band41b, and first and second combining protrusions31cand41c. Accordingly, the first and second combining protrusions31cand41cof the first and second rivets31and41may be respectively coupled to the first and second current collecting members50and70so that the first and second rivets31and41can be electrically connected to the first and second current collecting members50and70.

The first and second terminal plates32and42may be electrically connected to the first and second rivets31and41by being coupled thereto, and the first and second terminal connection pillars33and43may be coupled to the first and second terminal plates32and42. Thus, the first and second rivets (or terminal members)31and41electrically connect (e.g., along an electrical power current path) the electrode assembly10to the first and second terminal plates32and42. The first and second gaskets34and44may insulate the first and second rivets31and41from the cap plate20by being provided between the first and second rivets31and41and the cap plate20.

The terminal insulation member35may be provided between the first terminal plate32and the cap plate20for insulation therebetween. The auxiliary plate45may be provided between the second terminal plate42and the cap plate20. To increase surface contact between the parts, the second terminal plate42and the auxiliary plate45may have a level mating surface facing the cap plate20.

Here, the auxiliary plate45may be formed of a conductive material, and the cap plate20and the second current collecting member70can be electrically connected to each other through the auxiliary plate45. In addition, the case26is electrically connected to the second electrode12through the cap plate20such that the case26may be positively or negatively charged (e.g., have a first polarity). Thus, a polarity (positive or negative) of the cap plate20(e.g., the first polarity) may be changed (e.g., to a second polarity different from the first polarity) according to a polarity (positive or negative) of the second electrode12.

The first and second current collecting members50and70may respectively include first and second electrode combining portions51and71connected to the first and second electrodes11and12and first and second terminal combining portions52and72including first and second terminal combining grooves (at the first and second combining protrusions31cand41c) connected to the first and second terminal portions30and40.

In addition, first and second lower insulation members60and80may be disposed adjacent to the cap plate20in the case26. Here, the first terminal portion30may include a terminal (not shown) formed in the shape of a circular cylinder rather than a plate.

FIG. 3is a cross-sectional view ofFIG. 1, taken along the line III-III.FIG. 4is a partially exploded perspective view of the rechargeable battery ofFIG. 1.

Hereinafter, the rechargeable battery100ofFIG. 1will be described with reference toFIG. 3andFIG. 4. Referring toFIG. 3, the first electrode11may be disposed in an external surface of the electrode assembly10. In addition, the first electrode11may be formed as a negative electrode, and the second electrode12may be formed as a positive electrode. Thus, the case26that is electrically connected to the second electrode12through the second terminal portion40may be positively charged, and the second terminal plate42may be a positive terminal plate that is electrically connected to the case26. In addition, the positively charged case26and the negative first electrode11may be disposed opposite to each other, interposing the separator13therebetween.

However, the present invention is not limited thereto, and the first electrode11may be formed as a positive electrode and the second electrode12may be formed as the negative electrode. Thus, the case26that is electrically connected to the second electrode12through the second terminal portion40can be negatively charged.

Hereinafter, a current path formed between the case26, the first electrode11, the second terminal portion40, and the conductive foreign material90due to penetration of the conductive foreign material90when the case26is positively charged will be described in further detail.

As shown inFIG. 3, the conductive foreign material90penetrating one side of the positively charged case26can sequentially penetrate the insulating separator13of the electrode assembly10and the negative first electrode11. Here, the conductive foreign material90that penetrated the positively charged case26can be positively charged. Thus, when the conductive foreign material90penetrates the rechargeable battery100, a current path through which a current continuously flows may be formed between the negative first electrode11, the positively charged case26, the positive charged conductive foreign material90, and the second terminal portion40electrically connected to the positive second electrode12. Thus, the internal current of the electrode assembly (or current collector)10may flow to the outside of the electrode assembly10through the second terminal portion40provided on the cap plate20of the case26from the negative first electrode11, and may flow into the electrode assembly10through the conductive foreign material90, using the case26as a medium.

Referring toFIG. 4, the auxiliary plate45formed of the conductive material of the second terminal portion40may include a mesh structure451and be made of one of stainless and aluminum. In further detail, the mesh structure451may be formed of a plurality of mesh strands451aand a plurality of mesh holes451b. These mesh strands451acan be numerous and fine, thereby defining hundreds or thousands of mesh holes451b. Hereinafter, a current consumption process in the mesh structure451will be described.

As described above, a current discharged from the electrode assembly10when the conductive foreign material90sequentially penetrates the case26and the first electrode11may return to the conductive foreign material90by passing through the second terminal portion40. This current path will be referred to as a short circuit current path. For instance, the second terminal plate42may only be electrically connected to the cap plate20via the auxiliary plate45.

In further detail, the current discharged from the electrode assembly10may be passed through the auxiliary plate45where the mesh structure451is formed and then transmitted to the conductive foreign material90through the case26. In this case, the current passing through the auxiliary plate45passes through the plurality of mesh strands451a, each having a constant or uniform thickness. To this end, the auxiliary plate45may present a surface facing the second terminal plate42that is at least as large as a surface of the second terminal plate42facing the auxiliary plate45.

Since the current passes through the mesh strands451ain a line contact state, a relatively large amount of current can be consumed in the auxiliary plate45compared to a case of passing through a plate where the mesh structure451is not formed in a surface contact state. This is especially true with a large number (e.g., hundreds or thousands) of mesh holes451b. Thus, the amount of current flowing from the electrode assembly10and returning to the conductive foreign material90may be reduced by the auxiliary plate45formed in the mesh structure451. Accordingly, damage to the electrode assembly10due to heat or arcing generated in the conductive foreign material90can be reduced or prevented.

FIG. 5Ais a graph illustrating internal temperature variation of a comparable rechargeable battery in accordance with penetration of a conductive foreign material through the comparable rechargeable battery.FIG. 5Bis a graph illustrating internal temperature variation of the rechargeable battery ofFIG. 1in accordance with penetration of the conductive material through the rechargeable battery.

Referring back to theFIG. 2, according to the present exemplary embodiment, when conductive foreign material is completely penetrated through the rechargeable battery, an internal temperature of the rechargeable battery may be determined by measuring each of a temperature change of vent (Temp at VENT), a temperature change of a first part (A) (Temp at A), a temperature change of a second part (B) (Temp at B), a temperature change of a third part (C) (Temp at C) and a temperature change of a fourth part (D) (Temp at D)

Referring toFIG. 5A, a voltage V is instantaneously increased up to 4.166V when the conductive foreign material is completely penetrated through the comparable rechargeable battery, and according to the temperature change of the second part (B) (Temp at B), an internal temperature of the comparable rechargeable battery is increased up to 237° C. In contrast, referring toFIG. 5B, although it is the same as the comparable rechargeable battery in that a voltage is instantaneously increased up to 4.166V when the conductive foreign material is penetrated through the rechargeable battery according to the present exemplary embodiment ofFIG. 1, according to the temperature change of the second part (B) (Temp at B), the internal temperature of the rechargeable battery100is only increased up to 95° C.

Thus, according to the present exemplary embodiment ofFIG. 1, the current discharged from the electrode assembly10linearly contacts the auxiliary plate45of the second terminal portion40when passing therethrough due to the mesh structure451. Thus, consumption of the current occurs, and accordingly the amount of current returning to the conductive foreign material90is significantly reduced, thereby suppressing an increase of the internal temperature of the electrode assembly10.

FIG. 6is a partially exploded perspective view of a rechargeable battery according to a second exemplary embodiment of the present invention.

Referring toFIG. 6, a second terminal portion140of the rechargeable battery is substantially the same as the second terminal portion40of the rechargeable battery100of the exemplary embodiment ofFIG. 1, except for an auxiliary plate46of the second terminal portion140. Thus, a portion that is the same as the second terminal portion40according to the exemplary embodiment ofFIG. 1will not be repeated.

The auxiliary plate46of the second terminal portion140may include a plurality of grooves461(including top portions and recessed portions), and each of the plurality of grooves461may have a cross-section formed in the shape of a quadrangle. However, the cross-section of each of the grooves461formed in the auxiliary plate46is not limited to the shape of a quadrangle, and the shape of the cross-section may be, for example, one of a circle or a triangle.

There may be numerous such grooves461(for example, dozens or hundreds, such as 50 or more) to increase the current consumption of the auxiliary plate46in a short circuit current path. In addition, the top portions of the grooves461may form a level mating surface to face the second terminal plate42(to increase surface contact between the auxiliary plate46and the second terminal plate42and widen the current path between the second terminal plate42and the auxiliary plate46). The auxiliary plate46may also mate flush with the second terminal plate42or present a surface facing the second terminal plate42that is at least as large as a surface of the second terminal plate42facing the auxiliary plate46, for instance, to accomplish the same purposes. Further, the auxiliary plate46may mate flush with the cap plate20or have a level mating surface facing the cap plate as other ways to increase surface contact in the parts that make up the short circuit current path.

According to the present exemplary embodiment ofFIG. 6, when the conductive foreign material90sequentially penetrates the case26and the first electrode11and thus, the current discharged from the electrode assembly10returns to the conductive foreign material90passing through the auxiliary plate46of the second terminal portion140, the current may linearly contact the auxiliary plate46where the plurality of grooves461of the second terminal portion140are formed. Since the current passes through the auxiliary plate46while linearly contacting the auxiliary plate46, much more current can be consumed in the auxiliary plate46compared to a case that the current linearly contacts a plate where the grooves461are not formed.

That is, the amount of current returning to the conductive foreign material90may be reduced due to the auxiliary plate46where the plurality of grooves461is formed. Accordingly, damage to the electrode assembly due to heat or arcing generated in the conductive foreign material90can be reduced or prevented.

FIG. 7is a partially exploded perspective view of a rechargeable battery according to a third exemplary embodiment of the present invention.

Referring toFIG. 7, a rechargeable battery has the same configuration of the rechargeable battery100of the exemplary embodiment ofFIG. 1, except for a reinforcing plate47of a second terminal portion240. Thus, a portion that is the same as the second terminal portion40of the exemplary embodiment ofFIG. 1will not be repeated.

The second terminal portion240may further include a reinforcing plate (or reinforcement plate)47provided between a second terminal plate42and an auxiliary plate45. A mechanical strength of the auxiliary plate45including a mesh structure451may be weaker than a mechanical strength of a plate that does not include a mesh structure. Thus, the reinforcing plate47may be provided between the second terminal plate42and the auxiliary plate45to reinforce the mechanical strength of the auxiliary plate45.

For example, the reinforcing plate47can reduce the likelihood or prevent the mesh structure451of the auxiliary plate45from being damaged. In addition, heat generated in the auxiliary plate45may be absorbed into (or dissipated by) the reinforcing plate47by the current discharged from the electrode assembly10, and therefore damage to the auxiliary plate45due to the heat can be reduced or prevented. The reinforcement plate47may mate flush with the second terminal plate42to increase or maximize surface contact between the reinforcement plate47and the second terminal plate42.

In other embodiments, the reinforcing plate47may be provided between the auxiliary plate45and a cap plate20instead of being provided between the second terminal plate42and the auxiliary plate45. Further, the reinforcing plate47may be formed of one of a conductive material and a non-conductive material.

Description of some symbols100: rechargeable battery10: electrode assembly11: first electrode12: second electrode13: separator30: first terminal portion31: first rivet32: first terminal plate33: first terminal connection pillar34: first gasket35: terminal insulation member40, 140, 240: second terminal portion41: second rivet42: second terminal plate43: second terminal connection pillar44: second gasket45, 46: auxiliary plate451: mesh structure451a: mesh strand451b: mesh hole461: groove47: reinforcing plate50: first current collecting member51: first electrode combining portion52: first terminal combining portion60: first lower insulation member61: first current collecting member combining unit70: second current collecting member80: second lower insulation member