Patent Description:
A secondary battery is manufactured in various shapes, and typical examples thereof include a cylindrical shape and a square shape. The secondary battery may be manufactured by installing, in a case, an electrode assembly formed with a separator as an insulator interposed between positive and negative plates and an electrolyte, and installing a cap assembly in the case. The electrode assembly is electrically connected to an electrode terminal through a current collector plate. The internal volume of the case varies according to the structure of the current collector plate. The <CIT> discloses a secondary battery including an electrode assembly comprising an uncoated portion tab with a tape member on the uncoated portion tab, wherein a retainer is attached thereto and the electrode assembly is accommodated in an insulation bag. The <CIT> discloses a secondary battery providing improved welding quality and the <CIT> discloses a secondary battery including an electrode assembly and a wrapping tape.

According to the invention, a secondary battery is provided according to claim <NUM>.

The insulating sheet may have an adhesive on an inner surface thereof, and the insulating sheet may be coupled to the electrode assembly and the retainer by the adhesive.

A width of the retainer may not be less than <NUM> smaller than a width of the short side of the electrode assembly.

The retainer and the insulating sheet may be made of an electrically insulating material.

The insulating sheet may include polypropylene (PP).

The retainer may include at least one of polypropylene (PP) and polyimide (PI).

The insulating sheet has a seating portion and wing portions on both sides of the seating portion, one surface of the long side of the electrode assembly is attached to the seating portion of the insulating sheet, and the wing portions is bent from the seating portion to cover the short side of the electrode assembly and the retainer.

The wing portions of the insulating sheet may extend over another surface of the long side of the electrode assembly to cover the other surface of the long side.

The secondary battery may further include a pair of cap assemblies that are electrically coupled to both ends of the electrode assembly and coupled through both sides of the case.

Boundaries of the case and the cap assemblies may be welded to each other.

According to another aspect of the invention, a method of manufacturing a secondary battery is provided according to the features of claim <NUM>.

The insulating sheet has a seating portion and wing portions on both sides of the seating portion and the method includes the step of attaching one surface of the long side of the electrode assembly to the seating portion of the insulating sheet. The method further includes the step of bending and the wing portions from the seating portion to cover the short side of the electrode assembly and the retainer.

The method may further include the step of extending the wing portions of the insulating sheet over another surface of the long side portion of the electrode assembly to cover the other surface of the long side portion.

The method may further include to electrically couple a pair of cap assemblies to both ends of the electrode assembly and coupling the cap assemblies through both sides of the case.

The method may further include the step of welding boundaries of the case and the cap assemblies to each other.

Hereinafter, embodiments of the present disclosure will be described, in detail, with reference to the accompanying drawings.

Embodiments of the present disclosure are provided to more completely explain the present disclosure to those skilled in the art, and the following embodiments may be modified in various other forms. The present disclosure, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will convey the aspects and features of the present disclosure to those skilled in the art.

It will be understood that when an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it may be directly on, connected, or coupled to the other element or layer or one or more intervening elements or layers may also be present. When an element or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. For example, when a first element is described as being "coupled" or "connected" to a second element, the first element may be directly coupled or connected to the second element or the first element may be indirectly coupled or connected to the second element via one or more intervening elements.

In the figures, dimensions of the various elements, layers, etc. may be exaggerated for clarity of illustration. The same reference numerals designate the same elements. Further, the use of "may" when describing embodiments of the present disclosure relates to "one or more embodiments of the present disclosure. " Expressions, such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

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

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 device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the term "below" may encompass both an orientation of above and below. The device may be otherwise oriented (rotated <NUM> degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure. It will be further understood that the terms "includes," "including," "comprises," and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Hereinafter, a structure of a secondary battery according to embodiments of the present disclosure and a manufacturing process thereof will be described in detail.

<FIG> illustrates an insulating sheet used for a secondary battery according to an embodiment of the present disclosure.

The insulating sheet <NUM> is made of an electrically insulating material and may be composed of a single or multiple (or a plurality of) layers. The insulating sheet <NUM> may cover side surfaces of the electrode assembly to prevent the electrode assembly from coming into contact with the case and causing an electrical short. The insulating sheet <NUM> may include, for example, polypropylene (PP).

The insulating sheet <NUM> has a first wing portion <NUM> and a second wing portion <NUM> positioned on (e.g., extending from) opposite edges of the seating portion <NUM>. The seating portion <NUM> may have an area (e.g., a surface area) corresponding to a planar size of the electrode assembly. For example, the seating portion <NUM> is in contact with (be attached to) the lower surface of the electrode assembly. The wing portions <NUM> and <NUM> is folded upwardly to surround (or cover) the side surface of the electrode assembly while the electrode assembly is seated on the seating portion <NUM>. However, in an embodiment, because the front and rear ends of the electrode assembly are exposed, the electrode uncoated region of each electrode plate (e.g., of each polarity) may be exposed.

An adhesive component is applied to the inner surface of the seating portion <NUM> and the wing portions <NUM> and <NUM>, and thus, the insulating sheet <NUM> may be adhered to an electrode assembly <NUM> and/or to a retainer <NUM>, which is an internal component.

The retainer <NUM> may be provided between the seating portion <NUM> of the insulating sheet <NUM> and the wing portions <NUM> and <NUM>. The retainers <NUM> may be provided as a pair and may be respectively disposed on both sides (e.g., opposite sides) of the seating portion <NUM> of the insulating sheet <NUM>. In addition, the wing portions <NUM> and <NUM> of the insulating sheet <NUM> are folded upwardly together with the retainer <NUM> to be erect. For example, the wing portions <NUM> and <NUM> may stand up the retainer <NUM> (e.g., the retainer <NUM> may be vertically arranged) through bending and, thus, are respectively coupled to opposite sides of the electrode assembly. The retainer <NUM> may be coupled to two surfaces of the electrode assembly <NUM> facing each other having a relatively small area from among the four side surfaces of the electrode assembly <NUM>. Therefore, the retainer <NUM> can cover the side surfaces of the electrode assembly <NUM> and protect the side surfaces from being scratched in the process of coupling a case to the outside of the electrode assembly <NUM>, which will be described later, thereby preventing the electrode assembly <NUM> from being damaged.

The retainer <NUM> may be a sheet member. The retainer <NUM> may be made of an electrically insulating material, similar to the insulating sheet <NUM>. The retainer <NUM> may include polypropylene (PP) or high heat-resistant polyimide (PI). Accordingly, the retainer <NUM> may protect the side surfaces of the electrode assembly <NUM> while preventing the side surfaces of the electrode assembly <NUM> from contacting the case and being short-circuited.

The retainer <NUM> may have a width smaller than the width of the short side portion of the electrode assembly <NUM>. In particular, the retainer <NUM> may have a width that is not less than <NUM>, preferably not less than <NUM> or not less than <NUM>, smaller than the width of the short side portion (or short side surface) of the electrode assembly <NUM>. When the retainer <NUM> has a width that is smaller, in particular not less than <NUM> smaller, than the width of the short side portion of the electrode assembly <NUM>, even if the retainer <NUM> flows (e.g., moves on the insulating sheet <NUM>) before or when the insulating sheet <NUM> is folded to wrap the electrode assembly <NUM>, the width of the retainer <NUM> may not exceed the width of (e.g., may be extend or protrude beyond) the electrode assembly <NUM>, thereby preventing defects from occurring during the manufacture. A width difference may be illustrated in <FIG> and, after folding, in <FIG> and <FIG> where opposite end portions of the short side portions of the electrode assembly <NUM> are not covered by the retainer <NUM> due to the smaller width of the retainer <NUM> with respect to the width of the short side portion of the electrode assembly <NUM>.

The retainer <NUM> may not include a separate adhesive material on the inner surface thereof. Accordingly, physical or chemical damage that may occur to the electrode assembly due to an adhesive material on the retainer <NUM> may be avoided.

<FIG> illustrates a process in which the electrode assembly is seated on the insulating sheet shown in <FIG>.

Referring to <FIG>, the electrode assembly <NUM> is positioned and attached to the seating portion <NUM> of the insulating sheet <NUM>.

The electrode assembly <NUM> is formed by stacking a plurality of layers including a first electrode plate, a separator, and a second electrode plate, each having a thin plate shape or a film shape. In one embodiment, the first electrode plate may have a first polarity, for example, a positive electrode, and the second electrode plate may have a second polarity, for example, a negative electrode. However, the present disclosure is not limited thereto, and the first electrode plate and the second electrode plate may have any polarity as long as the first electrode plate and the second electrode plate have different polarities from each other.

The first electrode plate is formed by coating a first electrode active material, such as a transition metal oxide, on a first electrode current collector formed of a metal foil, such as aluminum, and has a first electrode uncoated portion that is a region at where the first active material is not applied. The first electrode uncoated portion provides a passage for current flow between the first electrode plate and the outside.

The first electrode uncoated portions of the first electrode plates may overlap each other at the same position (e.g., at a same end of the electrode assembly <NUM>) when the first electrode plates are stacked. For example, the first electrode uncoated portion protrudes toward one side of the electrode assembly <NUM>, and the electrode plate to be coupled thereafter is combined with the first electrode uncoated portion to have the same polarity as the first electrode plate.

The second electrode plate is formed by coating a second electrode active material, such as graphite or carbon, on a first electrode current collector formed of a metal foil, such as copper or nickel, and the second electrode uncoated portion is a region at where the second active material is not applied.

The second electrode uncoated portions of the second electrode plates may overlap each other at the same position (e.g., at a same end of the electrode assembly <NUM>) when the second electrode plates are stacked. For example, the second electrode uncoated portion protrude toward the other side of the electrode assembly <NUM> to be coupled to the electrode plate.

The separator is arranged between the first electrode plate and the second electrode plate to prevent short circuit and enable movement of lithium ions. The separator may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. The present disclosure, however, is not limited by the material of the separator.

The electrode assembly <NUM> is accommodated inside (e.g., substantially inside) the case together with the electrolyte. The electrolyte may be formed of a lithium salt, such as LiPF<NUM> or LiBF<NUM>, in an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). The electrolyte may be in a liquid, solid or gel phase.

For example, as shown in <FIG>, the electrode assembly <NUM> may have a short side portion <NUM>, a long side portion <NUM>, and an electrode uncoated portion <NUM>. From among these portions, the short side portion <NUM> and the long side portion <NUM> may form a side surface of the electrode assembly <NUM>, and a region having a relatively small area may be referred as the short side portion <NUM>, and a region having a relatively large area may be referred as the long side portion <NUM>. In addition, electrode uncoated portions <NUM> may be formed at opposite ends of the electrode assembly <NUM> to be connected to the respective electrode plates.

In addition, one surface of the long side portion <NUM> of the electrode assembly <NUM> may be positioned on the seating portion <NUM> of the insulating sheet <NUM> and adhered thereto.

<FIG> illustrate a folding process of the insulating sheet around the electrode assembly shown in <FIG>.

First, referring to <FIG>, the wing portions <NUM> and <NUM> of the insulating sheet <NUM> are bent along both edges of the side of the electrode assembly <NUM>. For example, the first wing portion <NUM> are bent upwardly in a state in which the retainer <NUM> is provided therein and are bent upwardly along one edge of the side portion from the lower surface corresponding to the long side portion <NUM> of the electrode assembly <NUM>. In addition, the second wing portion <NUM> are bent upwardly in a state in which the retainer <NUM> is provided therein and are bent upwardly along the other edge from the side portion of the lower surface of the electrode assembly <NUM>. Accordingly, as shown in <FIG>, the retainers <NUM> are in contact with both sides of the electrode assembly <NUM>, that is, the two short side portions <NUM>, respectively.

Next, referring to <FIG>, the first wing portion <NUM> is bent once again and attached to surround (or cover) the upper surface of the electrode assembly <NUM>. In an embodiment, the end portion of the first wing portion <NUM> may extend over <NUM>/<NUM> or more of the width of the upper surface of the long side portion <NUM> of the electrode assembly <NUM>. In addition, because the first wing portion <NUM> are attached to the upper surface of the electrode assembly <NUM> to have a fixed position, the retainer <NUM> located inside the first wing portion <NUM> is fixed to the side surface of the electrode assembly <NUM>.

Next, referring to <FIG>, the second wing portion <NUM> are bent and attached to surround (or cover) the upper surface of the long side portion <NUM> of the electrode assembly <NUM>. In addition, the second wing portion <NUM> may extend over <NUM>/<NUM> or more of the width of the upper surface of the electrode assembly <NUM>. According to this configuration, the end portion of the second wing portion <NUM> extends over the upper surface of the long side portion <NUM> to overlap the first wing portion <NUM> in some area. In addition, the overlapping area of the first wing portion <NUM> and the second wing portion <NUM> ensures that the upper surface of the electrode assembly <NUM> is completely covered. Because the second wing portion <NUM> is fixed to the upper surface of the electrode assembly <NUM> by being bent and attached thereto, the retainer <NUM> located inside the second wing portion <NUM> may be fixed to the side of the electrode assembly <NUM>.

<FIG> illustrates a process and a secondary battery <NUM> in which a current collector plate is coupled to the wrapped electrode assembly shown in <FIG>.

Referring to <FIG>, current collector plates <NUM> and <NUM> may be coupled to the front and rear ends of the electrode assembly <NUM>, which are exposed by the insulating sheet <NUM>, respectively. As described above, the electrode assembly <NUM> includes a first electrode uncoated portion extending from the first electrode plate and a second electrode uncoated portion extending from the second electrode plate, and the first and second electrode uncoated portions may be respectively formed as front and rear ends of the electrode assembly <NUM>. Accordingly, the first current collector plate <NUM> and the second current collector plate <NUM> may be coupled to the first electrode uncoated portion and the second electrode uncoated portion not covered by the insulating sheet <NUM>, respectively.

The first current collector plate <NUM> may include a current collecting portion <NUM> and a terminal portion <NUM>. The current collecting portion <NUM> may be coupled by contacting the first electrode uncoated portions of the electrode assembly <NUM>. The current collecting portion <NUM> may be arranged along the longitudinal direction of the first electrode uncoated portions of the electrode assembly <NUM> and may have a plurality of welding holes 141a formed in a direction perpendicular to the longitudinal direction of the current collecting portion <NUM>. By irradiating a beam through the welding hole 141a to perform laser welding, the current collecting portion <NUM> and the first electrode uncoated portions of the electrode assembly may be electrically connected.

The terminal portion <NUM> may protrude from an area of the current collecting portion <NUM>. The terminal portion <NUM> may be (e.g., may extend) substantially perpendicular to the current collecting portion <NUM>. Because the terminal portion <NUM> protrudes from the current collecting portion <NUM>, the structure of the cap assembly can be easily welded thereafter. In addition, after welding, the terminal portion <NUM> may be bent about <NUM> degrees to be parallel to the current collecting portion <NUM>, and through the bending operation of the terminal portion <NUM>, the cap assembly may be closely coupled to the opening of the case.

The second current collector plate <NUM> may similarly include a current collector <NUM> and a terminal <NUM>. The second current collector plate <NUM> is coupled to the second current collector uncoated portions of the electrode assembly <NUM>, and the configuration and operation thereof are the same or substantially the same as those of the first current collector plate <NUM>, and thus, a detailed description thereof will be omitted.

<FIG> illustrates a process and a secondary battery <NUM> in which an insulating member is coupled to the electrode assembly shown in <FIG>.

Referring to <FIG>, the insulating member <NUM> may be coupled from the outside of each of the current collector plates <NUM> and <NUM>. The insulating member <NUM> has a terminal hole (e.g., a terminal opening) <NUM> for exposing the terminal portions <NUM> and <NUM> while the current collecting portions <NUM> and <NUM> of the current collector plates <NUM> and <NUM> are covered from the outside so as not to be exposed. Accordingly, the current collector plates <NUM> and <NUM> are located inside the insulating member <NUM> and are not exposed to the outside, and only the terminal portions <NUM> and <NUM> are exposed to the outside through the terminal hole(s) <NUM>.

The insulating member <NUM> may be made of an electrically insulating material. For example, the insulating member <NUM> may include polypropylene (PP). Accordingly, the current collector plates <NUM> and <NUM> may be electrically independent (e.g., electrically isolated from each other) by the insulating member <NUM>, except at the position where they are welded to the cap assembly, which will be described later. Accordingly, an electrical short circuit does not occur in the secondary battery according to embodiments of the present disclosure.

The insulating member <NUM> may have an electrolyte injection hole (e.g., an electrolyte injection opening) <NUM> on one side to provide a path through which an electrolyte is injected into the inside of the case when the electrolyte is injected from the outside through the cap assembly after the coupling is completed.

<FIG> illustrates a process and a secondary battery <NUM> in which a case is coupled to the insulating sheet used shown in <FIG>.

Referring to <FIG>, the case <NUM> may be coupled to the coupling structure of the insulating sheet <NUM>, the retainer <NUM>, the electrode assembly <NUM>, the current collector plates <NUM> and <NUM>, and the insulating member <NUM>. The case <NUM> may be configured as a tube having openings 170a at both ends, and a structure including the electrode assembly <NUM> may be inserted and coupled through the openings 170a.

As described above, the retainer <NUM> is coupled to two surfaces of the electrode assembly <NUM> that face each other with a relatively small area from among the four side surfaces of the electrode assembly <NUM>, and the outside thereof is covered by the insulating sheet <NUM>. In addition, because the side surface of the electrode assembly <NUM> has a relatively narrow area, the side surface of the electrode assembly are likely to be scratched when the electrode assembly <NUM> is inserted into the opening 170a of the case <NUM>. However, because the retainer <NUM> surrounds (or covers) the side surface, the side surface may not be scratched. Accordingly, when the case <NUM> is coupled to the electrode assembly <NUM>, damage to the electrode assembly <NUM> can be prevented.

<FIG> illustrates a process and a secondary battery <NUM> in which cap assemblies is coupled to the electrode assembly shown in <FIG>.

Referring to <FIG>, the cap assemblies <NUM> and <NUM> may be coupled to the current collector plates <NUM> and <NUM>, respectively, from the outside of the electrode assembly <NUM>. For example, the terminal portions <NUM> and <NUM> of the current collector plates <NUM> and <NUM> may be exposed to the outside through the terminal hole (e.g., terminal opening) <NUM> in the insulating member <NUM>, respectively.

The cap assemblies <NUM> and <NUM> may include a first cap assembly <NUM> coupled to the first current collector plate <NUM> and a second cap assembly <NUM> coupled to the second current collector plate <NUM>.

The first cap assembly <NUM> may include a flat cap plate <NUM>, a terminal plate <NUM>, and an insulating plate <NUM>. The cap plate <NUM> has a flat plate shape and may have a shape matching the opening 170a in the case <NUM>. In addition, the cap plate <NUM> may be formed of the same material as the case <NUM>. The terminal plate <NUM> may be exposed to an upper portion of the cap plate <NUM> and may be electrically connected to the first current collector plate <NUM> therein through an electrode terminal penetrating the cap plate <NUM>. In addition, the insulating plate <NUM> provided on the terminal plate <NUM> may insulate the terminal plate <NUM> and the cap plate <NUM> to be electrically independent from each other. Accordingly, the terminal plate <NUM> may have the same polarity as the first current collector plate <NUM> and the first electrode uncoated portion, regardless of the cap plate <NUM>. In addition, an electrolyte injection hole (e.g., an electrolyte injection opening) <NUM> is formed in the cap plate <NUM> to provide a path through which an electrolyte is applied from the outside after the cap assembly <NUM> is assembled.

The second cap assembly <NUM> may include a flat cap plate <NUM>, a terminal plate <NUM>, and an insulating plate <NUM> and may be electrically connected to the second current collector plate <NUM>. The configuration and operation of the second cap assembly <NUM> are similar to those of the first cap assembly <NUM>, and thus, a detailed description thereof will be omitted.

<FIG> illustrates a process and a secondary battery <NUM> in which the case and the cap assembly shown in <FIG> are coupled together.

Referring to <FIG>, after the cap assemblies <NUM> and <NUM> are coupled, the terminal portions <NUM> and <NUM> of the current collector plates <NUM> and <NUM> are bent by about <NUM> degrees so that the cap plates <NUM> and <NUM> can be coupled to the openings 170a in the case <NUM>, respectively. In an embodiment, the terminal plates <NUM> and <NUM> may protrude to the outside of the cap plates <NUM> and <NUM>, respectively.

Then, welding may be performed along the boundaries of the cap plates <NUM> and <NUM> and the case <NUM>, respectively. The welding may be laser welding, and accordingly, the inside of the cap plates <NUM> and <NUM> and the case <NUM> may be sealed.

An electrolyte may be injected from the outside through the electrolyte injection hole <NUM> in the cap plate <NUM>, and then, the electrolyte injection hole <NUM> may be closed and sealed by a separate injection plug.

In the secondary battery manufactured according to embodiments of the present disclosure, the terminal plates <NUM> and <NUM> may be respectively positioned through (or in) both ends of the case <NUM>. Accordingly, lithium ions move through the entire area of the electrode assembly <NUM>, thereby preventing partial (or uneven) deterioration of the electrode assembly <NUM> and, thus, lifespan and efficiency may be increased.

Claim 1:
A secondary battery, comprising:
an electrode assembly (<NUM>) having a long side portion (<NUM>) and a short side portion (<NUM>);
a retainer sheet (<NUM>) coupled to the short side portion (<NUM>) of the electrode assembly (<NUM>);
an insulating sheet (<NUM>) surrounding a periphery of the electrode assembly (<NUM>) and the retainer (<NUM>);
a case (<NUM>) accommodating the electrode assembly (<NUM>), the retainer sheet (<NUM>), and the insulating sheet (<NUM>);
characterized in that,
the insulating sheet (<NUM>) has a seating portion (<NUM>) and wing portions (<NUM>, <NUM>) on both sides of the seating portion (<NUM>),
wherein one surface of the long side portion (<NUM>) of the electrode assembly (<NUM>) is attached to the seating portion (<NUM>) of the insulating sheet (<NUM>), and
wherein the wing portions (<NUM>, <NUM>) are bent from the seating portion (<NUM>) to cover the short side portion (<NUM>) of the electrode assembly (<NUM>) and the retainer sheet (<NUM>), and the wing portions (<NUM>, <NUM>) are attached to an opposite surface of the one surface of the long side portion (<NUM>) of the electrode assembly (<NUM>).