Patent Description:
Unlike a primary battery, a secondary battery can be repeatedly charged and discharged. A low-capacity secondary battery is used for various small portable electronic devices such as mobile phones, camcorders, or laptop computers, and a high-capacity secondary battery is extensively used as a power source for driving electronic devices such as a motor of a hybrid car or an electric car, a power storage cell, and the like.

In addition, the secondary battery may be classified as a cylindrical type, a prismatic type or a pouch type according to the external shape of the secondary battery. Among others, a prismatic secondary battery may include an electrode assembly, a case having a rectangular parallelepiped shape and accommodating the electrode assembly and an electrolyte, a cap plate sealing the case, and electrode terminals installed on the cap plate.

Secondary batteries of the state of art usually include an electrode assembly comprising a positive electrode plate having a positive electrode non-coating portion, a negative electrode plate having a negative electrode non-coating portion, and a separator between the positive electrode plate and the negative electrode plate. The positive electrode non-coating portion and the negative electrode non-coating portion are exposed at opposite sides of the electrode assembly. A case having a top opening and an internal space accommodates the electrode assembly and a cap plate seals the top opening of the case. A positive electrode current collector plate is welded to the positive electrode non-coating portion and a negative electrode current collector plate is welded to the negative electrode non-coating portion. A positive electrode terminal on the cap plate is electrically connected to the positive electrode current collector plate and a negative electrode terminal on the cap plate is electrically connected to the negative electrode current collector plate. Exemplary embodiments of secondary batteries are disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Embodiments of the present disclosure related to a secondary battery which is capable of increasing battery capacity and improving welding quality compared to related art secondary batteries.

According to the present invention there is provided a secondary battery are defined in claim <NUM>. The secondary battery includes an electrode assembly constructed in a stack type including a positive electrode plate having a positive electrode non-coating portion, a negative electrode plate having a negative electrode non-coating portion, and a separator between the positive electrode plate and the negative electrode plate, the positive electrode non-coating portion and the negative electrode non-coating portion being exposed at opposite sides of the electrode assembly, a case having a top opening and an internal space accommodating the electrode assembly, a cap plate sealing the top opening of the case, a positive electrode current collector plate perpendicular and welded to the positive electrode non-coating portion, a negative electrode current collector plate perpendicular and welded to the negative electrode non-coating portion, a positive electrode terminal on the cap plate and electrically connected to the positive electrode current collector plate, and a negative electrode terminal on the cap plate and electrically connected to the negative electrode current collector plate.

In addition, the electrode assembly also includes a second separator and the positive electrode plate, the separator, the negative electrode plate and the second separator may be sequentially stacked in Y-axis direction. A laser welding line, which joins the positive electrode current collector plate to the positive electrode non-coating portion, is formed along the Y-axis direction, and a laser welding line, which joins the negative electrode current collector plate to the negative electrode non-coating portion is formed along the Y-axis direction.

In addition, the positive electrode current collector plate and/or the negative electrode current collector plate may have an area equal to the cross-sectional area of the electrode assembly.

In addition, the electrode assembly may be wound about a winding axis into a jelly roll configuration such that the positive electrode non-coating portion is exposed at one end of the winding axis, and the negative electrode non-coating portion is exposed to the other end of the winding axis, and the winding axis is horizontally aligned on the top opening.

In addition, the electrode assembly may have a cross section elongated in a top-down direction, the cross section being perpendicular to the winding axis, and the electrode assembly may include a series of electrode assemblies that are stacked on each other along a direction transverse to the top-down direction.

In addition, the positive electrode current collector plate and/or the negative electrode current collector plate may have an area equivalent to the overall area of cross sections of the series of electrode assemblies.

In addition, the positive electrode non-coating portion is in line-contact with the positive electrode current collector plate, and the negative electrode non-coating portion is in line-contact with the negative electrode current collector plate.

In addition, an entirety of the positive electrode current collector plate may contact an entirety of the positive electrode non-coating portion, and an entirety of the negative electrode current collector plate may contact an entirety of the negative electrode non-coating portion.

As described above, according to embodiments of the present disclosure, since an electrode non-coating portion is in line-contact with an electrode current collector plate, the area of the electrode non-coating portion can be reduced, compared to a related art secondary battery where the electrode non-coating portion is in surface-contact with the electrode current collector plate, thereby increasing battery capacity, and ultimately simplifying the manufacturing process.

Hereinafter, embodiments of the present disclosure will be described in detail.

In addition, in the accompanying drawings, sizes or thicknesses of various components are exaggerated for brevity and clarity. 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 therebetween such that the element A and the element B are indirectly connected to each other.

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 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.

It will be understood that, although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers and/or sections, these members, elements, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one member, element, region, layer and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer and/or a second section without departing from the teachings of the present disclosure.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. For example, if the element or feature in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "on" or "above" the other elements or features.

<FIG> is a perspective view of a secondary battery <NUM> according to an embodiment of the present disclosure, and <FIG> is an exploded view of the secondary <NUM> battery according to an embodiment not falling under the present invention.

Referring to <FIG> and <FIG>, the secondary battery <NUM> according to an embodiment includes an electrode assembly <NUM>, a case <NUM>, a cap plate <NUM>, a positive electrode current collector plate <NUM>, a negative electrode current collector plate <NUM>, a positive electrode terminal <NUM>, and a negative electrode terminal <NUM>.

The electrode assembly <NUM> includes a positive electrode plate <NUM>, a negative electrode plate <NUM>, and a separator <NUM> between the positive electrode plate <NUM> and the negative electrode plate <NUM>.

The positive electrode plate <NUM> has a positive electrode coating portion with a positive electrode active material coated thereon, and a positive electrode non-coating portion 111A without a positive electrode active material coated thereon. The positive electrode coating portion (including, for example, a transition metal oxide) is formed on a positive electrode current collector made of, for example, an aluminum foil, and the positive electrode non-coating portion 111A is formed along one side of the positive electrode current collector.

In addition, the negative electrode plate <NUM> has a negative electrode coating portion with a negative electrode active material coated thereon, and a negative electrode non-coating portion 112A without a negative electrode active material coated thereon. The negative electrode coating portion (including, for example, carbon or graphite) is formed on a negative electrode current collector made of, for example, a copper or nickel foil, and the negative electrode non-coating portion 112A is formed along one side of the negative electrode current collector.

The separator <NUM> is an insulator and may be made of, for example, polyethylene, polypropylene, or a composite film of polypropylene and polyethylene. The separator <NUM> is located between the positive electrode plate <NUM> and the negative electrode plate <NUM> to prevent a short circuit from occurring between the positive electrode plate <NUM> and the negative electrode plate <NUM> and to allow the movement of lithium ions.

The electrode assembly <NUM>, including the positive electrode plate <NUM>, the negative electrode plate <NUM> and the separator <NUM>, is wound about a winding axis into a so-called jelly roll configuration. In one or more embodiments, the positive electrode non-coating portion 111A is wound about the winding axis so as to be exposed at one end of the winding axis, and the negative electrode non-coating portion 112A is wound about the winding axis so as to be exposed at the other end of the winding axis. In <FIG>, the winding axis is aligned along the X-axis direction, the positive electrode non-coating portion 111A is exposed at the minus (-) side in the X-axis direction, and the negative electrode non-coating portion 112A is exposed at the plus (+) side in the X-axis direction. Accordingly, in the illustrated embodiment, the winding axis is horizontally aligned with the top opening of the case <NUM>.

In addition, in one or more embodiments, a cross-sectional shape of the electrode assembly <NUM> in a plane perpendicular to the winding axis (e.g., a Y-Z plane) may be a circle, or may be an ellipse, or an oblong shape that is elongated along the Z axis direction. Accordingly, in one or more embodiments, the electrode assembly <NUM> has a cross section in a plane perpendicular to the winding axis (e.g., a Y-Z plane) that is elongated in a top-down direction (i.e., a direction along the Z-axis). Additionally, in the illustrated embodiment, the plurality of electrode assemblies <NUM> are stacked along a direction transverse to the top-down direction (e.g., the plurality of electrode assemblies <NUM> are stacked in the Y-axis direction).

Additionally, the electrode assembly <NUM> may include a plurality of electrode assemblies, which are adjacently stacked one on another along the Y-axis direction.

The case <NUM> is shaped of a substantially rectangular parallelepiped having an internal space and a top opening (e.g., an open top). Accordingly, the internal space of the case <NUM> may serve to accommodate the electrode assembly <NUM> and an electrolyte.

The electrolyte may include, for example, an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and a lithium salt such as LiPF<NUM> or LibF<NUM>.

The cap plate <NUM> is coupled to a top end of the case <NUM> and seals the top surface of the case <NUM> (e.g., the cap plate <NUM> covers or closes the top opening of the case <NUM>). The case <NUM> and the cap plate <NUM> may be made of, for example, aluminum, and welded together.

In addition, the cap plate <NUM> may have an electrolyte injection hole and a vent hole.

The electrolyte injection hole is provided for injecting an electrolyte into the interior space of the case <NUM> after the cap plate <NUM> is coupled to the case <NUM>. Once the electrolyte is injected, the electrolyte injection hole is sealed by a plug <NUM>.

The vent hole is configured to discharge or vent internal gases generated inside the case <NUM> and thereby prevent an explosion due to the internal gases generated inside the case <NUM>. The vent hole is sealed by a vent member <NUM> at normal times, and is opened as the vent member <NUM> is naturally ruptured when the internal pressure of the case <NUM> reaches a certain level (e.g., the vent member <NUM> is configured to rupture when a threshold internal pressure is reached inside the case <NUM>). In addition, the vent member <NUM> may have a notch 132A formed therein that is configured to facilitate the rupturing of the vent member <NUM> around the notch 132A.

The positive electrode current collector plate <NUM> may be formed of, for example, an aluminum plate, and may be perpendicular to the positive electrode non-coating portion 111A. The positive electrode current collector plate <NUM> may be welded to the positive electrode non-coating portion 111A. In one or more embodiments, the positive electrode non-coating portion 111A is in line-contact with the positive electrode current collector plate <NUM>. With this structure, the area of the positive electrode non-coating portion 111A may be reduced, compared to an embodiment in which the positive electrode non-coating portion 111A is in surface-contact with the positive electrode current collector plate <NUM>, thereby increasing battery capacity of the secondary battery <NUM>.

In addition, the positive electrode current collector plate <NUM> may be formed to have an area equivalent or substantially equivalent to an area of the overall cross sections of the positive electrode non-coating portions 111A of the plurality of electrode assemblies <NUM>, and thus an entirety or substantially an entirety of the positive electrode current collector plate <NUM> may contact an entirety or substantially an entirety of the positive electrode non-coating portions 111A of the plurality of electrode assemblies <NUM>. Accordingly, resistance between the positive electrode non-coating portion 111A and the positive electrode current collector plate <NUM> may be minimized or at least reduced compared to a second battery not having this configuration.

In one or more embodiments, the positive electrode current collector plate <NUM> may be welded to the positive electrode non-coating portion 111A by a laser. In this embodiment, during the task of laser welding the positive electrode current collector plate <NUM> to the positive electrode non-coating portion 111A, the laser may be irradiated along the Y-axis direction. In other words, the laser welding line joining the positive electrode current collector plate <NUM> to the positive electrode non-coating portion 111A may be formed along the Y-axis direction. In one or more embodiments, the laser may be irradiated with an appropriate intensity so as not to completely fuse the positive electrode current collector plate <NUM> or the positive electrode non-coating portion 111A. If the laser irradiated is strong enough to completely fuse the positive electrode current collector plate <NUM>, foreign substances (for example, spattered substances) may be induced to the electrode assembly <NUM>, which may result in a short circuit or other damage to the secondary battery <NUM>. However, if the laser irradiated is not strong enough to completely fuse the positive electrode current collector plate <NUM>, the above-described problem(s) can be avoided.

In addition, since the electrode assembly <NUM> is wound into a jelly roll configuration, the self-supporting ability of the positive electrode non-coating portion 111A may be increased by the curvature thereof. Therefore, the positive electrode non-coating portion 111A may be prevented from being undesirably deformed when the positive electrode current collector plate <NUM> is pressed against the positive electrode non-coating portion 111A.

Moreover, since the electrode assembly <NUM> comprises a plurality of electrode assemblies, each of the plurality of electrode assemblies may be relatively narrow and long for a given interior volume of the case <NUM>, compared to an embodiment in which the electrode assembly <NUM> includes only a single electrode assembly. The self-supporting ability of the positive electrode non-coating portion 111A may be further increased by allowing the positive electrode non-coating portion 111A to have larger curvatures at top and bottom ends thereof, which also improves weld quality between the positive electrode non-coating portion 111A and the positive electrode current collector plate <NUM>.

The negative electrode current collector plate <NUM> may be formed of, for example, a copper or nickel plate, and may be perpendicular to the negative electrode non-coating portion 112A. The negative electrode current collector plate <NUM> may be welded to the negative electrode non-coating portion 112A.

The negative electrode current collector plate <NUM> may also be formed to have an area equivalent or substantially equivalent to an area of the overall cross sections of negative electrode non-coating portions 112A of a plurality of electrode assemblies <NUM>, and thus an entirety or substantially an entirety of the negative electrode current collector plate <NUM> may contact an entirety or substantially an entirety of the negative electrode non-coating portions 112A of the plurality of electrode assemblies <NUM>.

In one or more embodiments, the negative electrode current collector plate <NUM> may be welded to the negative electrode non-coating portion 112A by a laser. In this embodiment, during the task of laser welding the negative electrode current collector plate <NUM> to the negative electrode non-coating portion 112A, the laser may be irradiated along the Y-axis direction with an appropriate intensity so as not to completely fuse the negative electrode current collector plate <NUM> or the negative electrode non-coating portion 112A.

Since the resulting effects are substantially the same as those described above with respect to the positive electrode current collector plate <NUM> and the positive electrode non-coating portion 111A, a repeated description thereof will be omitted.

The positive electrode terminal <NUM> is installed on the cap plate <NUM> and is electrically connected to the positive electrode current collector plate <NUM>.

In addition, the negative electrode terminal <NUM> is installed on the cap plate <NUM> and is electrically connected to the negative electrode current collector plate <NUM>.

If the positive electrode terminal <NUM> is in contact with the cap plate <NUM>, an insulation member <NUM> is provided between the negative electrode terminal <NUM> and the cap plate <NUM> (e.g., the negative electrode terminal <NUM> is spaced apart, and electrically isolated, from the cap plate <NUM> by the insulation member <NUM>) to prevent a short circuit.

<FIG> is an exploded view of a secondary battery <NUM> according to an embodiment of the present invention.

The secondary battery <NUM> according to another embodiment differs from the secondary battery <NUM> described above with reference to <FIG> and <FIG> in that the former includes an electrode assembly <NUM> constructed in a stack type, and the other details are substantially the same in both embodiments, and thus repeated descriptions of the common components and/or features will be omitted. The common components and/or features of the embodiment illustrated in <FIG> and the embodiment illustrated in <FIG> are identified with the same reference numbers.

Referring to <FIG>, the electrode assembly <NUM> includes a positive electrode plate <NUM>, a separator <NUM>, a negative electrode plate <NUM>, and another separator <NUM> sequentially stacked in that order. In the resulting stack, a positive electrode non-coating portion 211A and a negative electrode non-coating portion 212A are exposed on opposite sides. In <FIG>, the positive electrode non-coating portion 211A is exposed at the minus (-) side in the X-axis direction and the negative electrode non-coating portion 212A exposed at the plus (+) side in the X-axis direction.

In the illustrated embodiment, the secondary battery <NUM> also includes a positive electrode current collector plate <NUM> and a negative electrode current collector plate <NUM> coupled to the cap plate <NUM>. The positive electrode current collector plate <NUM> may be perpendicular to the positive electrode non-coating portion 211A, and the positive electrode current collector plate <NUM> may be welded to the positive electrode non-coating portion 211A (e.g., by a laser). The positive electrode current collector plate <NUM> has an area equivalent or substantially equivalent to a cross-sectional area of the electrode assembly <NUM> in the Y-Z plane.

The negative electrode current collector plate <NUM> may be perpendicular to the negative electrode non-coating portion 212A, and the negative electrode current collector plate <NUM> may be welded to the negative electrode non-coating portion 212A (e.g., by a laser). The negative electrode current collector plate <NUM> has an area equivalent or substantially equivalent to a cross-sectional area of the electrode assembly <NUM> in the Y-Z plane.

Claim 1:
A secondary battery (<NUM>) comprising:
an electrode assembly (<NUM>) comprising a positive electrode plate (<NUM>) having a positive electrode non-coating portion (211A), a negative electrode plate (<NUM>) having a negative electrode non-coating portion (212A), and a separator (<NUM>) between the positive electrode plate (<NUM>) and the negative electrode plate (<NUM>), the positive electrode non-coating portion (211A) and the negative electrode non-coating portion (212A) being exposed at opposite sides of the electrode assembly (<NUM>);
a case (<NUM>) having a top opening and an internal space accommodating the electrode assembly (<NUM>);
a cap plate (<NUM>) sealing the top opening of the case (<NUM>);
a positive electrode current collector plate (<NUM>) perpendicular to the positive electrode non-coating portion (211A) and welded to the positive electrode non-coating portion (211A);
a negative electrode current collector plate (<NUM>) perpendicular to the negative electrode non-coating portion (212A) and welded to the negative electrode non-coating portion (212A);
a positive electrode terminal (<NUM>) on the cap plate (<NUM>) and electrically connected to the positive electrode current collector plate (<NUM>);
a negative electrode terminal (<NUM>) on the cap plate (<NUM>) and electrically connected to the negative electrode current collector plate (<NUM>),
wherein the electrode assembly (<NUM>) further comprises a second separator (<NUM>), and the positive electrode plate (<NUM>), the separator (<NUM>), the negative electrode plate (<NUM>), and the second separator (<NUM>) are sequentially stacked along a Y-axis direction, and wherein a laser welding line joining the positive electrode current collector plate (<NUM>) to the positive electrode non-coating portion (211A) is formed along the Y-axis direction, and a laser welding line joining the negative electrode current collector plate (<NUM>) to the negative electrode non-coating portion (212A) is formed along the Y-axis direction, and
wherein the positive electrode non-coating portion (211A) is in line-contact with the positive electrode current collector plate (<NUM>) and the negative electrode non-coating portion (212A) is in line-contact with the negative electrode current collector plate (<NUM>).