Patent Description:
The present invention relates to an electrode assembly and a method for manufacturing the same, and more particularly, to an electrode assembly, which is capable of being manufactured in an irregular shape suitable for a device to be mounted and has improved toughness against an external impact, and a method for manufacturing the same.

The demand for secondary batteries as energy sources is rapidly increasing in various fields comprising personal portable terminal and electric vehicle fields.

Unlike primary batteries, rechargeable secondary batteries are being developed not only for digital devices but also for vehicles such as electric vehicles.

Secondary batteries are variously classified according to materials and external shapes of a positive electrode and a negative electrode. Among them, since such a lithium secondary battery using a lithium compound material has large capacity and a low self-discharge rate, the lithium secondary battery is being widely used as power sources of various electrical devices instead of a nickel-cadmium secondary battery according to the related art.

Also, the lithium secondary battery may be manufactured in various shapes. Representatively, the lithium secondary battery may be classified into a cylinder type secondary battery, a prismatic type secondary battery, and a pouch type secondary battery. Here, an electrode assembly for charging and discharging electric energy is built in a case. The electrode assembly has a structure in which a negative electrode, a separator, and a positive electrode are stacked and is built together with an electrolyte in the case (the pouch or cylinder type case or the like).

Secondary batteries that have been recently developed may have may have an irregular shape suitable for a size and/or shape of a mounting space according to the battery mounting space of a device to be mounted. For example, each of both ends of a straight portion is bent at a right angle. Here, the bent portions may have a 'c' shape in which the bent portions are formed in parallel to each other in the same direction or an 'L' shape in which one side of the straight portion is bent at a right angle. The irregularly-shaped secondary battery having the above-described shape is manufactured by customizing a pouch (or a case and the like) according to the shape of an irregular electrode assembly.

However, such the irregularly-shaped secondary battery may be vulnerable to the external impact when compared to the conventional structure in which both ends are symmetrical in size. That is, in the case of the conventional structure, an impact may be dispersed even though the impact is applied from one side thereof. However, in the case of the '<IMG>' shape or the '<IMG>' shape, there is a problem that a risk of damage due to an external impact relatively increases because the impact is concentrated at the bent point. Document <CIT> discloses a method for manufacturing an electrode assembly comprising a laminate with an irregular shape.

Accordingly, to solve the above problem, a main object of the present invention is to provide an electrode assembly having improved safety to reduce a risk of damage due to an external impact and a method for manufacturing the same.

To achieve the above-described object, a method for manufacturing an electrode assembly according to the present invention is defined in the appended set of claims, the method comprises: a step of forming each of a negative electrode, a separator, and a positive electrode so as to have a shape having a hole; a step of laminating the negative electrode, the separator, and the positive electrode so that the holes are aligned so as to manufacture a unit cell; a step of laminating at least two or more unit cells to form a laminate; a step of folding a folding separator having an area that is enough to cover an entire surface of the laminate to wrap the outside of the laminate; a step of removing a portion of a space forming part that is a portion surrounding a space formed by the holes when the folding separator is folded to be wrapped along a periphery of the laminate; and a step of bonding surplus parts that are portions of the folding separator, which are not closely attached to the laminate, to each other after the portion of the space forming part is removed so as to finish the folding separator to cover an exposed surface of the laminate. Here, each of the holes refers to a hole that is excavated in any direction or opened. For example, the hole may have a shape of which a portion is excavated in a lateral direction as illustrated in <FIG> and <FIG> or a shape having a portion that is vertically penetrated as illustrated in <FIG>.

The unit cell has a shape of which at least one or more locations are bent. For example, the unit cell may have a shape (i.e., a 'c' shape) of which both ends having a straight line shape are bent at a right angle, but the bent portions are parallel to each other in the same direction or a shape (i.e., a '<IMG>' shape) of which one end having a straight line shape is bent at a right angle.

According to the present invention, the folding separator is made of a material having toughness greater than that of the separator laminated between the negative electrode and the positive electrode in the unit cell, wherein the folding separator may be bonded when heat is applied thereto. The term "toughness" as used herein means mechanical properties of the separator which is capable of being obtained through a kind and thickness of a separator source, a composition of a coating layer applied thereon, and a thickness adjustment, and the like. The unit cell may have a mono-cell structure in which the separator, the negative electrode, the separator, and the positive electrode are sequentially laminated upward.

The space forming part may be cut from the laminate, in which the folding separator is folded, by using a forming device, wherein the space forming part is removed so that the surplus parts remain by a size that is enough to cover the surface of the laminate to finish the folding separator by bonding the surplus parts to each other.

Furthermore, the present invention provides an electrode assembly as defined in the appended set of claims, the electrode assembly according to the present invention comprises: a laminate manufactured by laminating a plurality of unit cells, each of which is manufactured by laminating a negative electrode, a separator, and a positive electrode and has a shape of which at least one or more locations are bent; and a folding separator made of a material having toughness greater than that of the separator laminated between the negative electrode and the positive electrode in the unit cell, having an area that is enough to cover an entire surface of the laminate, and folded in one direction to surround the surface of the laminate, wherein the folding separator is finished so that surplus parts that are remaining portions of the folding separator after the laminate is folded cover the exposed surface of the laminate.

The prevent invention having the above-described configuration may have the effect of improving the safety against the external impact because the folding separator additionally wraps the electrode assembly even though the electrode assembly has the irregular shape according to the mounting conditions.

The folding separator may have the relatively greater hardiness than that of the separator and also be easily finished because the folding separator adheres when the heat is applied.

The present invention relates to an electrode assembly, which is manufactured in an irregular shape such as a '<IMG>', '<IMG>', or '<IMG>' shape except for a general rectangular or cylindrical shape and has improved toughness against an external impact, and a method for manufacturing the same. Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

This embodiment provides a method for manufacturing an electrode assembly having an irregular shape (a shape having a hole). As illustrated in <FIG>, in the manufacturing method according to the present invention, a negative electrode <NUM>, a separator <NUM>, and a positive electrode <NUM> are manufactured in the same shape capable of being laminated and then are laminated to form a unit cell <NUM>. Thereafter, at least two or more unit cells <NUM> (preferably, about ten unit cells <NUM>) are laminated to form a laminate <NUM>, and a folding separator <NUM> is folded to surround the laminate <NUM>.

In more detail, in the manufacturing method, first, each of the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM> is formed in the same shape (which is capable of being laminated even if sizes are somewhat different from each other), i.e., in a shape having a hole. Here, each of the holes refers to a hole that is excavated in any direction or opened. For example, the hole may have a shape of which a portion is excavated in a lateral direction as illustrated in <FIG> and <FIG> or a shape having a portion that is vertically penetrated as illustrated in <FIG>.

That is, each of the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM> may be manufactured in a rectangular flat plate shape like the conventional shape and then be manufactured in 'c' of <FIG>, '<IMG>' of <FIG>, and '<IMG>' of <FIG> through a punching device p as illustrated in <FIG>.

Here, the above-described shapes have space forming parts a, b, and c covering a portion in which a space is formed when the folding separator <NUM> is wrapped (for reference, in <FIG>, the space forming part is removed so that a region in which the space forming part is formed is distinguished, and the region in which the space forming part is defined is indicated by a dotted line).

Also, as illustrated in <FIG>, the negative electrode <NUM>, the separator <NUM>, and the positive electrode <NUM> are laminated in the form of a unit cell <NUM> having a mono-cell structure in which the separator <NUM>, the negative electrode <NUM>, and the separator <NUM>, and the positive electrode <NUM> are sequentially laminated upward. Here, at least two or more unit cells <NUM> (preferably, about ten unit cells) may be laminated to form one laminate <NUM>.

Then, as illustrated in <FIG>, the laminate <NUM> is transferred onto the folding separator <NUM>, and the folding separator <NUM> is folded in one direction to wrap the laminate <NUM>. Here, the folding separator <NUM> has an area that is enough to cover an entire surface of the laminate <NUM> and be folded in one direction to wrap the laminate <NUM> so that a space is formed between the folding separator <NUM> and the laminate <NUM>. Thus, the space forming part a that is a region surrounding an inner space and surplus parts s, t, u, v, and w protruding respectively from edges of the laminate <NUM> are formed in the folding separator <NUM>.

The space forming part a is removed by a forming device (not shown) for cutting or incising the folding separator <NUM> while pressing the folding separator <NUM> from one side, like the punching device p of <FIG>. Here, the space forming part a is cut to a predetermined size (that is enough to cover the surface of the laminate) in which the surplus part r is additionally formed (i.e., only a portion of the space forming part is cut to be removed).

Also, the surplus parts r, s, t, u, v, and w are bonded to each other so that the laminate <NUM> is sealed by the folding separator <NUM>. That is, when the folding is performed, some of the surplus parts r, s, t, u, v, and w protruding from the edges of the laminate <NUM> as a remaining portion of the folding separator <NUM> without being closely attached to the laminate <NUM> may be cut to be additionally folded to cover the exposed surface of the laminate <NUM> in a state of being cut to be discarded or partially overlapping each other. Here, ends of the surplus parts r, s, t, u, v, and w are bonded to each other to be finished.

Here, the folding separator <NUM> has toughness greater than that of the separator <NUM> laminated between the negative electrode <NUM> and the positive electrode <NUM> in the unit cell <NUM>. In addition, the folding separator <NUM> may be made of a material that is capable of being bonded when heat is applied thereto. Thus, when the heat is applied in a state in which the surplus parts r, s, t, u, v, and w cover the exposed surface of the laminate <NUM>, the folding separator <NUM> may be finished while maintaining in the above-described state.

In this embodiment, the laminate <NUM> is formed in a shape in which the space forming part is formed when the folding separator <NUM> is folded, for example, a shape in which the unit cell <NUM> is bent at one or more locations. For example, the unit cell <NUM> may have a shape (i.e., the 'c' shape) of which both ends having a straight line shape are bent at a right angle, but the bent portions are parallel to each other in the same direction as illustrated in <FIG>, a shape (i.e., the '<IMG>' shape) of which one end having a straight line shape is bent at a right angle as illustrated in <FIG>, or a shape (i.e., the '<IMG>' shape) of which one side having a straight line shape is bent at a right angle as illustrated in <FIG>.

For reference, in this embodiment, since the punching device for punching the negative electrode <NUM>, the separator <NUM>, and the positive electrode to have the above-described shapes and the forming device for cutting the space forming part a are used by utilizing well-known devices, their detailed description will be omitted.

Furthermore, the present invention additionally provides an electrode assembly according to Embodiment <NUM>, which is manufactured through the manufacturing method.

In this embodiment, the electrode assembly is manufactured so that a surface of a laminate <NUM> is finished by a folding separator <NUM>. The laminate <NUM> is manufactured by laminating a plurality of unit cells <NUM>, each of which is manufactured by laminating a negative electrode <NUM>, a separator <NUM>, and a positive electrode <NUM> and has a shape of which at least one or more locations are bent. The folding separator <NUM> is made of a material having toughness greater than that of the separator <NUM> laminated between the negative electrode <NUM> and the positive electrode <NUM> in the unit cell <NUM>. Also, the folding separator <NUM> has an area that is enough to cover an entire surface of the laminate <NUM> and is folded in one direction to surround the surface of the laminate <NUM>.

Here, the folding separator <NUM> is finished as illustrated in <FIG> so that surplus parts r, s, t, u, v, and w remaining after folding the laminate <NUM> cover the exposed surface of the laminate <NUM>.

For reference, although not shown, a portion on which an electrode tab protruding from the electrode assembly and connected to the outside is formed may be configured to be selectively exposed through the folding separator within a range that does not affect performance of the electrode assembly according to the folding direction of the folding separator <NUM> or the finishing manner of the surplus parts r, s, t, u, v, and w.

The prevent invention having the above-described configuration may have the effect of improving the safety against the external impact because the folding separator <NUM> additionally wraps the electrode assembly even though the electrode assembly has the irregular shape according to the mounting conditions.

The folding separator <NUM> may have the relatively greater hardiness than that of the separator <NUM> and also be easily finished because the folding separator adheres when the heat is applied.

Claim 1:
A method for manufacturing an electrode assembly, the method comprising:
a step of forming each of a negative electrode (<NUM>), a separator (<NUM>), and a positive electrode (<NUM>) so as to have a shape having a hole;
a step of laminating the negative electrode (<NUM>), the separator (<NUM>), and the positive electrode (<NUM>) so that the holes are aligned so as to manufacture a unit cell (<NUM>);
a step of laminating at least two or more unit cells to form a laminate (<NUM>);
a step of folding a folding separator (<NUM>) having an area that is enough to cover an entire surface of the laminate (<NUM>) in one direction to wrap the outside of the laminate;
a step of removing a portion of a space forming part (a) that is a portion of the folding separator (<NUM>) surrounding a space formed by the holes when the folding separator (<NUM>) is folded to be wrapped along a periphery of the laminate (<NUM>); and
a step of bonding surplus parts (s, t, u, v, w)that are portions of the folding separator (<NUM>), which are not closely attached to the laminate (<NUM>), to each other after the portion of the space forming part is removed so that the laminate (<NUM>) is sealed by the folding separator (<NUM>) which covers an exposed surface of the laminate,
wherein the unit cell (<NUM>) has a shape in which it is bent at one location, at least,
wherein the folding separator (<NUM>) is made of a material having toughness greater than that of the separator laminated between the negative electrode and the positive electrode in the unit cell.