Electrode assembly having bending portions and secondary battery including the same

A secondary battery having positive and negative electrode plates inserted into the interior of a pouch, and positive and negative electrode active material layers respectively coated on the positive and negative electrode plates are arranged at a constant interval. Bending portions are provided to bend positive and negative electrode non-coating portions respectively not coated with the positive and negative electrode active material layers.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application earlier filed in the Korean Intellectual Property Office on Sep. 2, 2010 and there duly assigned Serial No. 10-2010-0085949.

BACKGROUND OF THE INVENTION

Field of the Invention

An aspect of the present invention relates to an electrode assembly and a secondary battery.

Description of the Related Art

In a secondary battery, it is increasingly required to use a shape that is suitable for various environments. However, in a conventional prismatic or cylindrical secondary battery, its shape is difficult to be freely modified. On the other hand, in the case of a pouch-type polymer battery, its shape may be modified to a certain extent. If the shape of the pouch-type polymer battery is freely modified, its application field can be greatly extended. However, an electrode assembly built in the pouch-type polymer battery should maintain a fixed shape. Therefore, it is technically required to modify the shapes of an electrode assembly and an outer casing, built in a pouch-type polymer battery for it to be suitable for different environments.

SUMMARY OF THE INVENTION

Aspects of the present invention provide for an electrode assembly having bending portions that enable to the electrode assembly to be freely folded or unfolded.

Still further, aspects of the present invention provide for a pouch-type secondary battery with a built-in electrode assembly, which has the structure of an outer casing capable of being more easily folded or unfolded according to the shape of the electrode assembly.

According to an aspect of the present invention, there is provided an electrode assembly including bending portions, the electrode assembly including: one or more positive electrode plates each having positive electrode active material layers formed by intermittently coating a positive electrode active material on a positive electrode collector and positive electrode non-coating portions respectively formed between the positive electrode active material layers; one or more negative electrode plates each having negative electrode active material layers formed by intermittently coating a negative electrode active material on a negative electrode collector and negative electrode non-coating portions respectively formed between the negative electrode active material layers; tab portions respectively formed to be extended from the positive and negative electrode plates; and one or more separators each interposed between the positive and negative electrode plates, wherein one or more of the positive and negative electrode non-coating portions have bending portions that enables the electrode assembly to be bent.

According to another aspect of the present invention, there is provided a secondary battery including a pouch-type case that accommodates the electrode assembly.

The bending portions may include bending lines formed at one or more of the positive and negative electrode non-coating portions. Separate concave groove portions may be formed at sides of regions of the positive and negative electrode non-coating portions, in which the bending lines are formed, respectively

Separate auxiliary concave groove portions may be further formed at sides of positions of the separator, corresponding to the positions at which the bending portions are formed, respectively.

The electrode assembly may be formed by stacking a plurality of electrode assemblies.

The case may be provided with electrode-plate damage prevention plates respectively formed in regions corresponding to the positive and negative electrode active material layers of the electrode assembly. The electrode-plate damage prevention plate may be formed with a plastic or metal plate

The electrode-plate damage prevention plates may be attached to inner or outer surfaces of the case using a double-faced adhesive tape.

The case may be provided with separate bending display portions respectively formed in regions corresponding to the bending portions of the electrode assembly.

As described above, according to aspects of the present invention, the shape of the secondary battery can be variously modified by providing an electrode assembly capable of be freely folded or unfolded.

Also, the secondary battery having the electrode assembly built therein can be applied to various fields.

DETAILED DESCRIPTION OF THE INVENTION

In order to clarify the present invention, elements extrinsic to the description are omitted from the details of this description, and like reference numerals refer to like elements throughout the specification.

In several exemplary embodiments, constituent elements having the same configuration are representatively described in a first exemplary embodiment by using the same reference numeral and only constituent elements other than the constituent elements described in the first exemplary embodiment will be described in other embodiments.

FIG. 1shows an electrode assembly of a pouch-type secondary battery according to an embodiment of the present invention.

As shown inFIG. 1, the electrode assembly50according to this embodiment has a structure in which a positive electrode plate10, a separator30and a negative electrode plate20are stacked. The positive electrode plate10may be formed by repeatedly forming positive electrode active material layers11and positive electrode non-coating portions70on both surfaces of a positive electrode collector. Here, the positive electrode active material layer11is formed by coating a positive electrode active material on both the surfaces of the positive electrode collector, and the positive electrode non-coating portion70is formed by coating no positive electrode active material on both surfaces of the positive electrode collector17. Meanwhile, the negative electrode plate20may be formed by repeatedly forming negative electrode active material layers21and negative electrode non-coating portions70on both surfaces of a negative electrode collector27. Here, the negative electrode active material layer21may be formed by coating a negative electrode active material on both the surfaces of the negative electrode collector, and the negative electrode non-coating portion70may be formed by coating no negative electrode active material on both surfaces of the negative electrode collector. That is, the positive and negative electrode active material layers11and21may be intermittently coated in a stripe shape on the respective positive and negative electrode plates10and20, and both the positive and negative electrode non-coating portions70are provided between the positive and negative electrode active material layers11and21, respectively. Separate electrode tabs16and26may be formed at the positive and negative electrode plates10and20, respectively.

The separator30may be interposed between the positive and negative electrode plates10and20to form the electrode assembly50. The electrode assembly50may be built in a separate pouch case60.

In this embodiment, the positive and negative electrode non-coating portions70have bending portions that enable them to be bent, so that the whole or a part of the electrode assembly can be folded or unfolded. That is, in the pouch-type secondary battery according to this embodiment, the entire shape of the electrode assembly can be modified by forming the bending portions that enable the positive and negative electrode non-coating portions70not respectively coated with the positive and negative electrode active material layers11and21to be bent.

Referring back toFIG. 1, in this embodiment, the positive and negative electrode active material layers11and12may be continuously formed in a stripe shape at a constant interval on the positive and negative electrode plates10and20, respectively. The positive and negative electrode active material layers11and12may be formed in the same area so that they can be identically overlapped with each other when the positive and negative electrode non-coating portions70are bent. In this embodiment, if the positive and negative electrode non-coating portions70are bent, the positive and negative electrode active material layers11and21are overlapped with each other, and the positive and negative electrode plates10and20may be formed in a zigzag pattern.

The electrode assembly50of this embodiment may be built in the pouch case60, and may be bent in various shapes. For example, the secondary battery including the pouch case60having the electrode assembly50built therein may be entirely folded by bending the positive and negative electrode non-coating portions70, if necessary. Alternatively, the folded secondary battery may be unfolded, if necessary. That is, the secondary battery has a folding/unfolding structure that enables it to be folded or unfolded like an accordion. The folding/unfolding structure means a structure of which folding or unfolding operation is possible.

FIGS. 2A to 2Dmore specifically show various bending portions in the electrode assembly according to the embodiment. In these figures, the bending portions of this embodiment will be more clearly described by exaggerating the size of the separator30in the electrode assembly as compared with those of the positive and negative electrode plates10and20.

InFIG. 2A, the positive and negative electrode plates10and20have bending lines71formed on the positive and negative electrode non-coating portions70not respectively coated with the positive and negative electrode active material layers11and21. Here, the bending lines71serve as bending portions that enable the positive and negative electrode plates10and20to be easily bent.

InFIG. 2B, semicircular concave groove portions80are formed at sides of the portion at which the bending line71is formed. The electrode assembly can be more easily folded or unfolded along the bending lines71thanks to the concave groove portions80.

InFIG. 2C, bending portions are similar to the bending lines ofFIG. 2A, but have another shape different from the bending lines ofFIG. 2A. The bending portions are formed with a plurality of holes72spaced apart from one another at a constant interval. The holes72enable the electrode assembly to be more easily folded or unfolded.

InFIG. 2D, auxiliary concave groove portions81are formed on the separator30so that the electrode assembly can be more easily folded or unfolded.

The bending lines71, the plurality holes72, the concave groove portions80and the auxiliary concave groove portions81as the aforementioned bending portions will be described in detail.

In this embodiment, the bending line71pressurizes a surface of each of the positive and negative electrode non-coating portions70to form a region thinner than other regions. Thus, the bending lines71enable the electrode assembly to be more easily bent. Meanwhile, as shown inFIG. 2C, a number of holes72punched in a vertical direction at a constant interval. Thus, the electrode assembly can be effectively folded or unfolded along the holes72formed in the width direction perpendicular to the length direction of the electrode assembly. However, in the case of the bending lines71may be spaced apart from one another so that the positive and negative electrode plates10and20themselves are not cut away or broken down.

In this embodiment, the concave groove portions having various shapes are formed at both the outermost sides of the bending line71that is a bending portion, i.e., at both the sides of each of the positive and negative electrode non-coating portions70, respectively, so that the electrode assembly can be more easily bent. The shape of the concave groove portion80may be any one of a circular shape, an elliptic shape, a wedge shape and a polygonal shape.

In this embodiment, the auxiliary concave groove portions81may be formed on the separator30interposed between the positive and negative electrode plates10and20. The auxiliary concave groove portions81may be formed at sides of regions of the separator30, corresponding to the regions in which the bending lines71are formed, respectively. The regions of the separator30are identical to the regions in which the concave grooves80formed at the sides of the positive and negative electrode non-coating portions70are formed, respectively. Thus, when the electrode assembly of this embodiment is formed by stacking the positive electrode plate10, the separator30and the negative electrode plate20, the auxiliary concave groove portions81are formed at a constant interval at positions on the sides of the separator30, corresponding to the positions at which the bending portions are formed, respectively. The auxiliary concave groove portions81are used to enable the electrode assembly to be more easily folded or unfolded.

FIGS. 3A and 3Bare views showing a secondary battery in which electrode-plate damage prevention plates may be formed according to embodiments of the present invention.

In the electrode assembly described in this embodiment, bending lines71and concave groove portions80may be formed on at least one of the positive and negative electrode non-coating portions as bending portions having various shapes, or auxiliary concave groove portions81may be separately formed on the separator30, so that the electrode assembly can be easily folded or unfolded.

In another embodiment, there is provided a pouch case60having the electrode assembly built therein. The pouch case60may further include bending portions similar to the bending portions of the electrode assembly in regions respectively corresponding to the regions in which the bending portions of the electrode assembly are formed. Electrode-plate damage prevention plates90are formed in the pouch case60so that it is possible to prevent the positive and negative electrode plates10and20from being damaged when the electrode assembly is folded or unfolded.

As shown inFIGS. 3A and 3B, the electrode-plate damage prevention plates90are attached to inner or outer surfaces of the pouch case60, respectively corresponding to the positive and negative electrode active material layers11and21coated on surfaces of the positive and negative electrode plates10and20.

The electrode-plate damage prevention plate90may be formed using a metal or plastic plate having a constant thickness. The electrode-plate damage prevention plates90are used to prevent the positive and negative electrode active material layers11and21from being damaged or broken when the electrode assembly provided with the bending portions is folded or unfolded. Meanwhile, bending display portions61may be formed in a line shape between the electrode-plate damage prevention plates90attached to the inner or outer surfaces of the pouch case60, respectively. The bending display portions61are formed at positions corresponding to the bending lines71formed on the positive and negative electrode non-coating portions70of the electrode assembly, respectively, so that the secondary battery including the electrode assembly can be more easily folded or unfolded.

The electrode-plate damage prevention plates90functions to enable the secondary battery to be more easily bend and to protect the positive and negative electrode plates10and20. The portion at which the positive and negative electrode plates10and20are overlapped with each other is a battery cell, and the battery cell functions to collect electrons and positive charges. If the portion is bent or damaged, a serious problem may occur. Thus, the electrode-plate damage prevention plates90may also function to prevent the pouch case60from being bent at portions of the pouch case60, respectively corresponding to the portions at which the positive and negative electrode active material layers11and21are formed in the positive and negative electrode plates10and20, and the like.

InFIG. 3A, the electrode-plate damage prevention plates90are formed on the inner surfaces of the pouch case60, respectively. On the contrary, inFIG. 3B, the electrode-plate damage prevention plates90are formed on the outer surfaces of the pouch case60, respectively. Similarly, in the embodiment shown inFIG. 3B, the electrode-plate damage prevention plates90are attached to the outer surfaces of the pouch case60, corresponding to the positive and negative electrode active material layers11and21, respectively, so that it is possible to protect the positive and negative electrode plates10and20and to enable the positive and negative electrode non-coating portions70to be more easily bent. Separate bending display portions61may be provided between the electrode-plate damage prevention plates90, respectively.

The electrode-plate damage prevention plate90may be formed using a thin metal or plastic plate as described above. However, since the electrode-plate damage prevention plate90has a higher hardness than the pouch case60, a portion of the pouch case60, to which the electrode-plate damage prevention plate90is attached, may have a hardness to a certain extent in which it is not bent or modified when the pouch case60and the electrode assembly are bent. The electrode-plate damage prevention plate90may be attached to the pouch case60using a double-faced adhesive tape91. It will be apparent that the electrode-plate damage prevention plate90may be attached to the pouch case60using an adhesive.

FIG. 4is a view showing a bent shape of a secondary battery according to an embodiment of the present invention.

That is, in the pouch-type secondary battery according to this embodiment, the electrode-plate damage prevention plates90are attached to the inner or outer surfaces of a pouch case60, respectively. Subsequently, separate bending display portions61are formed on regions of the pouch case60, corresponding to the positive and negative electrode non-coating portions71and the positions at which the bending lines71are formed, respectively, so that the pouch case60can be more easily bent.

That is, in a case where the separate bending display portions61are formed on the outer surfaces of the pouch case60, respectively, they enable the pouch case60to be more easily folded or unfolded together with the bending lines71of the electrode assembly built in the pouch case60.

In this embodiment, the electrode assembly built in the pouch case60by stacking the positive electrode plate10, the negative electrode plate20and the separator30may be formed into a multi-layered structure. That is, an electrode assembly formed into a multi-layered structure is accommodated in the interior of the pouch case60, and bending portions are formed to enable the electrode assembly to be more easily folded or unfolded. Accordingly, the pouch-type secondary battery can be used in various fields that require high generation efficiency.