Patent Description:
Rechargeable batteries are classified into coin type batteries, cylindrical type batteries, prismatic type batteries, and pouch type batteries according to a shape of a battery case. In such a secondary battery, an electrode assembly mounted in a battery case is a chargeable and dischargeable power generating device having a structure in which an electrode and a separator are stacked.

Also, the electrode assembly may be approximately classified into a jelly-roll type electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, each of which is provided as the form of a sheet coated with an active material, and then, the positive electrode, the separator, and the negative electrode are wound, a stacked type electrode assembly in which a plurality of positive and negative electrodes with a separator therebetween are sequentially stacked, and a stack/folding type electrode assembly in which stacked type unit cells are wound together with a separation film having a long length.

Recently, the pouch-type battery in which a stack/folding type electrode assembly is built in a pouch-type battery case provided as an aluminum lamination sheet is attracting much attention due to its low manufacturing cost, light weight, easy shape deformation, and the like, and thus, its usage is gradually increasing.

In the case of the L-shaped pouch-type battery, there have been cases in which pouch cracks occur in an L-shape section during pouch forming, and a criterion of a residual amount of aluminum (AL) is not satisfied.

[Prior Art Document] (Patent Document) <CIT>.

Document <CIT> discloses a method for manufacturing a pouch for a secondary battery.

One aspect of the present invention is to provide a method for manufacturing a secondary battery, which is capable of preventing cracks occurring in a bending section when forming from occurring and capable of improving a residual amount of aluminum.

To this end, the invention relates to a manufacturing method according to claim <NUM>.

The manufacturing method after the invention may comprise one or more feature(s) from the dependent claims <NUM> to <NUM>, in any combination allowed by the claims.

According to the present invention, when forming the pouch of the pouch-type secondary battery having the bent shape, the arc slit cut may be performed in the section adjacent to the accommodating part having the bent shape in the pouch to relieve the stress generated in the bent-shaped section and improve the residual amount of aluminum.

The objectives, specific advantages, and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that the reference numerals are added to the components of the drawings in the present specification with the same numerals as possible, even if they are illustrated in other drawings. Also, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the following description of the present invention, the detailed descriptions of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

<FIG> is a plan view illustrating a cutting process in a method for manufacturing a secondary battery according to an embodiment of the present invention, <FIG> is a plan view illustrating a forming process in the method for manufacturing the secondary battery according to an embodiment of the present invention, <FIG> is a plan view illustrating an accommodating process in a method for manufacturing a secondary battery according to an embodiment of the present invention, and <FIG> is a perspective view illustrating a sealing process in the method for manufacturing the secondary battery according to an embodiment of the present invention.

Referring to <FIG>, a method for manufacturing a secondary battery according to an embodiment of the present invention comprises a forming process of forming an accommodating part <NUM> in a pouch <NUM>, a cutting process of cutting a portion of the pouch <NUM> adjacent to an inner corner portion in the accommodating part <NUM>, and an accommodating process of accommodating an electrode assembly <NUM> into the pouch <NUM> after the forming process to manufacture a secondary battery <NUM>. In addition, the method for manufacturing the secondary battery according to an embodiment of the present invention may further comprise a sealing process for sealing the pouch <NUM>.

Hereinafter, the method for manufacturing the secondary battery according to an embodiment of the present invention will be described in more detail.

Referring to <FIG> and <FIG>, in the cutting process, a portion of the pouch <NUM> is slit-cut in an arc shape to form a cutting part <NUM>.

Also, in the cutting process, the cutting part <NUM> isformed in consideration of a position at which the accommodating part <NUM> that accommodates the electrode assembly <NUM> will be formed in a subsequent process. That is, in the cutting process, the cutting part <NUM> is formed at the portion of the pouch <NUM> adjacent to the inner corner portion <NUM> in the bent accommodating part <NUM>.

In addition, in the cutting process, the cutting part <NUM> may be formed in an arc shape that is convex toward the inner corner portion <NUM> of the pouch <NUM> accommodating part <NUM>.

In addition, in the cutting process, the cutting part <NUM> is formed as an arc-shaped cutting line in the plan view.

<FIG> is a plan view illustrating a first example of the cutting part formed on the pouch in the method for manufacturing the secondary battery according to an embodiment of the present invention, <FIG> is a plan view illustrating a second example of the cutting part formed on the pouch in the method for manufacturing the secondary battery according to an embodiment of the present invention, and <FIG> is a plan view illustrating a third example of the cutting part formed on the pouch in the method for manufacturing the secondary battery according to an embodiment of the present invention.

Referring to <FIG>, in the cutting process, the arc-shaped cutting line of the cutting part <NUM> may be formed in an arc shape at an angle, for example, <NUM>° to <NUM>° (degrees). Here, in the cutting process, the arc-shaped cutting line of the cutting part <NUM> may be formed at an angle of <NUM> degrees or more to effectively improve thinning of the pouch, and the cutting line may be formed at an angle of <NUM> degrees or less to prevent the portion of the pouch <NUM>, which is cut as the arc-shaped cutting line, from being torn or separated, thereby realizing the thinning of the pouch.

Also, In the cutting process, the arc-shaped cutting line of the cutting part <NUM> may be specifically formed, for example, in an arc shape at an angle of <NUM> degrees to <NUM> degrees. Here, in the cutting process, a radius of the arc of the cutting part <NUM> may be, for example, <NUM> to <NUM>.

More specifically, for example, referring to <FIG>, in the cutting process, the arc-shaped cutting line of the cutting part <NUM> may be formed at an angle t1 of <NUM> degrees as a first example, and referring to <FIG>, the arc-shaped cutting line of the cutting part <NUM> may be formed at an angle t2 of <NUM> degrees as a second example. In addition, referring to <FIG>, the arc-shaped cutting line of the cutting part <NUM> may be formed at an angle t3 of <NUM> degrees as a third example.

In addition, in the cutting process, the cutting part <NUM> may be formed to be spaced a predetermined interval from the accommodating part <NUM>. That is, in the cutting process, the cutting part <NUM> may formed to be spaced a predetermined interval from the accommodating part <NUM> in consideration of a position of the accommodating part <NUM> to be formed in the subsequent forming process. In this case, in the cutting process, for example, the interval b between the cutting part <NUM> and the accommodating part <NUM> may be formed to be <NUM> to <NUM>.

The pouch <NUM> may comprise an aluminum (Al) material. In this case, for example, the pouch <NUM> may comprise an aluminum layer and a resin layer.

Referring to <FIG>, in the forming process, the accommodating part <NUM> having the bent shape is formed in the pouch <NUM> to accommodate the bent electrode assembly <NUM> after the cutting process. Here, the accommodating part <NUM> may be formed as, for example, a cup-shaped groove. In this case, the accommodating part <NUM> may be formed in an upwardly opened shape. Here, the 'bent shape' does not mean that the electrode assembly <NUM> and the accommodating part <NUM> are bent by external force, but may mean, for example, a vertically extending shape.

Furthermore, in the forming process, the accommodating part <NUM> may be formed in a shape corresponding to the electrode assembly <NUM>.

In the forming process, for example, the accommodating part <NUM> may be formed by pressing the pouch <NUM> from the top to the bottom through a punch.

Here, the electrode assembly <NUM> may be formed in a shape bent at a right angle. In this case, the electrode assembly <NUM> may be formed to be bent in an "L" shape.

In addition, in the forming process, the accommodating part <NUM> may be formed in a shape bent at a right angle. In this case, the forming process, the accommodating part <NUM> may be formed to be bent in an "L" shape.

In addition, in the forming process, the inner corner portion <NUM> of the pouch <NUM> may be formed in a shape that is recessed in a direction of the accommodating part <NUM> in the plan view. Here, the inner corner portion <NUM> may be formed, for example, in a shape that is recessed in a round shape. Here, as the arc-shaped cutting part <NUM> is formed at a distance adjacent to the inner corner portion <NUM> in the previous cutting process, an occurrence of excessive stress generated when the inner corner portion <NUM> is formed in a recessed shape in the forming process may be solved to effectively prevent cracks from occurring.

The electrode assembly <NUM> is a power generating element that is chargeable and dischargeable and forms a structure in which electrodes and separators are combined and alternately stacked.

The electrodes may comprise a positive electrode and a negative electrode. Also, each of the separators separates the positive electrode from the negative electrode to electrically insulate the positive electrode from the negative electrode.

The separator is alternately stacked with the positive electrode and the negative electrode, which are made of insulation materials.

Also, each of the separator <NUM> may be, for example, a multi-layered film produced by microporous polyethylene, polypropylene, or a combination thereof or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymers.

An electrode lead <NUM> may be connected to the electrode assembly <NUM> so as to be electrically connected to the outside. That is, the electrode lead <NUM> may be connected to the electrode of the electrode assembly <NUM> to electrically connect the electrode to an external terminal.

Referring to <FIG>, in the accommodating process, the electrode assembly <NUM> may be accommodated in the accommodating part <NUM> of the pouch <NUM> after the forming process.

In addition, in the accommodating process, an upper portion of the accommodating part <NUM> in which the electrode assembly <NUM> is accommodated may be covered. That is, the other side of the pouch <NUM> may be folded with respect to a folding line F of the pouch <NUM> to cover the accommodating part <NUM> formed at one side of the pouch <NUM> with respect to the folding line F of the pouch <NUM>.

In addition, an inner corner of the electrode assembly <NUM> may be formed in a shape corresponding to the inner corner portion <NUM> formed in the recessed shape in the pouch <NUM>. That is, an inner corner portion of the electrode assembly <NUM> may be formed in a shape corresponding to the inner corner portion <NUM> formed in the recessed shape of the pouch <NUM>.

Referring to <FIG>, in the sealing process, an outer circumferential surface of the pouch <NUM> may be sealed to seal the pouch <NUM>. In this case, in the sealing process, heat may be applied along an edge of the accommodating part <NUM> of the pouch <NUM> to form the sealing part.

In addition, the sealing process may comprise a removing process of cutting and removing a portion remaining except for the accommodating part <NUM> and the sealing part. In this case, in the removing process, the cutting part <NUM> of the pouch <NUM> may be removed together.

Referring to <FIG>, in the method for manufacturing the secondary battery according to an embodiment of the present invention, which is configured as described above, when the pouch <NUM> of the pouch-type battery having the bent shape is formed, arc slit cutting may be performed in a section A adjacent to a portion at which the bent-shaped accommodating part <NUM> is formed in the pouch <NUM> to relieve an occurrence of stress generated in the adjacent section A of the bent-shaped accommodating part <NUM>, thereby preventing cracks from occurring and improving a residual amount of aluminum.

Referring to <FIG>, the secondary battery may be a product manufactured by the method for manufacturing the secondary battery according to the embodiment of the present invention, which is configured as described above.

Referring to <FIG>, a portion of a pouch <NUM>' was slit-cut in an arc shape to form a cutting part <NUM>' to form a bent-shaped accommodating part <NUM>. Here, the cutting part <NUM>' was formed in the portion of the pouch <NUM>' adjacent to an inner corner portion of the bent accommodating part <NUM>. Here, the cutting part <NUM>' was formed in an arc shape having an angle t1 of <NUM> degrees. The cutting part <NUM>' was formed so that a radius R of the cutting part <NUM>' is <NUM>, and a spaced distance b between the cutting part <NUM>' and the accommodating part <NUM> is <NUM>.

Referring to <FIG>, the same process as in Manufacturing Example <NUM> was performed except that an angle t2 of a cutting part <NUM>'' of a pouch <NUM>" is formed in an arc shape having an angle of <NUM> degrees.

Referring to <FIG>, the same process as in Manufacturing Example <NUM> was performed except that an angle t3 of a cutting part <NUM>‴ of a pouch <NUM>"' is formed in an arc shape having an angle of <NUM> degrees.

The same process as in Manufacturing Example <NUM> was performed except that slit cutting is performed in a pouch to form a cutting part in a straight line shape.

<FIG> is a plan view illustrating reference symbols of portions of the pouch that has undergone the cutting process and the forming process in the method for manufacturing the secondary battery according to an embodiment of the present invention, and <FIG> is an image illustrating a ratio of thinning at a portion P6 of the pouch illustrated in <FIG>.

Here, FEA simulation was performed to measure a maximum thinning ratio of the pouch at each portion of the pouch illustrated in <FIG>, and thus, the results were shown in Table <NUM> below. Then, the thinning ratio of the pouch at an inner corner portion P6 illustrated in <FIG> was measured, and an image of <FIG> was shown. Here, the thinning of the pouch at the inner corner portion P6 in Comparative Example <NUM>, Manufacturing Example <NUM>, Manufacturing Example <NUM>, and Manufacturing Example <NUM> in the order of <FIG> (see <FIG>).

Referring to Table <NUM>, it is confirmed that an effect of thinning of the pouch in Manufacturing Examples <NUM> to <NUM>, in which the arc slit cutting is performed, is improved compared to Comparative Example <NUM>, in which the cutting part of the pouch is formed in the straight line shape. Particularly, it is seen that the thinning ratio of the pouch at the inner corner portion P6 of the pouch is <NUM>% in Comparative Example <NUM>, <NUM>% in Manufacturing Example <NUM>, <NUM>% in Manufacturing Example <NUM>, and <NUM>% in Manufacturing Example <NUM>. Here, it is seen that an amount of inflow from a portion P4 part to the portion P6 of the pouch increases, and thus, a thinning value of the pouch decreases to improve a residual amount of AI. That is, it is seen that an effect of the thinning of the pouch is improved by about <NUM>% in Manufacturing Examples <NUM> to <NUM> when compared to that of the thinning of the pouch at the inner corner portion P6 of the pouch.

Claim 1:
A method for manufacturing a secondary battery (<NUM>), the method comprising:
a cutting process of slit-cutting a portion of a pouch (<NUM>) to form a cutting part (<NUM>);
a forming process of forming an accommodating part (<NUM>) to accommodate an electrode assembly (<NUM>) in the pouch (<NUM>) after the cutting process; and
an accommodating process of accommodating the electrode assembly (<NUM>) in the accommodating part (<NUM>) of the pouch after the forming process,
characterized in that the electrode assembly has a bent shape,
in that the accommodating part (<NUM>) is formed in a bent shape in the forming process, and
in that, in the cutting process, the cutting part (<NUM>) is cut in an arc shape and formed at a portion of the pouch (<NUM>), which is adjacent to an inner corner portion (<NUM>) in the accommodating part (<NUM>) having the bent shape.