Patent Description:
Such a secondary battery may be configured so that an electrode assembly is built in a battery case. The electrode assembly mounted in the battery case is a chargeable/dischargeable power generating device having a structure in which a positive electrode/a separator/a negative electrode are stacked.

<FIG> is a plan view illustrating a stacked type electrode assembly of electrode assemblies according to the related art. <FIG> is a cross-sectional view illustrating the stacked type electrode assembly of the electrode assemblies according to the related art.

Referring to <FIG> and <FIG>, a plurality of unit cells <NUM> are stacked to constitute an electrode assembly <NUM>. However, when a large number of unit cells <NUM> are stacked, a degree of alignment of the electrode assembly <NUM> may be deteriorated. This is done because, when a large amount of unit cells <NUM> are stacked, a unit cell <NUM> which is not kept in place, but is separated from the stacked unit cells <NUM> easily occurs. <CIT>, <CIT> and <CIT> disclose electrode assemblies and methods for manufacturing such electrode assemblies. The preambles of claims <NUM> and <NUM> are based on document <CIT>.

As described above, when the plurality of unit cells are stacked to manufacture the electrode assembly, a degree of alignment of the electrode assembly may be easily deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electrode assembly having an improved degree of alignment in a stacked type electrode assembly and a method for manufacturing the same. Particularly, an object of the present invention is to provide an electrode assembly having a structure that is capable of being improved in productivity, in which a degree of alignment of the electrode assembly is capable of being improved through a low-cost and high-efficiency method, and a method for manufacturing the same. Also, an object of the present invention is to provide an electrode assembly that is capable of being improved in degree of alignment of the electrode assembly while preventing wetting from being deteriorated and a method for manufacturing the same.

An electrode assembly according to present invention is defined in claim <NUM>.

A method for manufacturing an electrode assembly is defined in claim <NUM>.

According to the electrode assembly and the method for manufacturing the same according to the present invention, in the stacked type electrode assembly, the degree of alignment of the electrode assembly may be improved, and particularly, in the electrode assembly having the structure that is capable of being improved in productivity, the degree of alignment of the electrode assembly may be improved through the high efficiency method. In addition, the degree of alignment of the electrode assembly may be improved while preventing the wetting from being deteriorated.

Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments below.

<FIG> is a conceptual view illustrating a zigzag-stacked structure in an electrode assembly according to Embodiment <NUM> of the present invention. <FIG> is a conceptual view illustrating another shape of the zigzag-stacked structure in the electrode assembly according to Embodiment <NUM> of the present invention. <FIG> is a cross-sectional view of a first unit cell in the electrode assembly according to Embodiment <NUM> of the present invention. <FIG> is a cross-sectional view of a second unit cell in the electrode assembly according to Embodiment <NUM> of the present invention. <FIG> is a perspective view illustrating a method for manufacturing the electrode assembly according to Embodiment <NUM> of the present invention. <FIG> is a perspective view illustrating the electrode assembly according to Embodiment <NUM> of the present invention.

Hereinafter, an electrode assembly according to Embodiment <NUM> of the present invention will be described with reference to <FIG>.

Referring to <FIG>, the electrode assembly according to Embodiment <NUM> of the present invention comprises a separator sheet <NUM> and unit cells <NUM> and <NUM>. The separator sheet <NUM> is folded in a zigzag shape, and the unit cells <NUM> and <NUM> may be repeatedly disposed between the separator sheet <NUM> that is folded in the zigzag shape (see <FIG>). Here, the unit cells <NUM> and <NUM> may have a structure in which electrodes <NUM> and <NUM> and a separator <NUM> are alternately stacked. Also, each of the unit cells <NUM> and <NUM> may be provided as one unit because the electrodes <NUM> and <NUM> and the separator <NUM> provided in the unit cells <NUM> and <NUM> are bonded to each other through lamination.

Particularly, the unit cells <NUM> and <NUM> may comprise a first unit cell <NUM> and a second unit cell <NUM>. <FIG> illustrates the first unit cell <NUM>, and <FIG> illustrates the second unit cell <NUM>. Referring to <FIG>, the first unit cell <NUM> comprises a first electrode <NUM>, a separator <NUM>, a second electrode <NUM>, a separator <NUM>, and a first electrode <NUM>, which are sequentially stacked. Here, the first electrode <NUM> may be a positive electrode.

The second unit cell <NUM> comprises a second electrode <NUM>, a separator <NUM>, a first electrode <NUM>, a separator <NUM>, and a second electrode <NUM>, which are sequentially stacked. Here, the second electrode <NUM> may be a negative electrode.

Referring to <FIG>, the electrode assembly according to Embodiment <NUM> of the present invention may have a structure in which the first unit cell <NUM> and the second unit cell <NUM> are repeatedly disposed and alternately stacked between the separator sheet <NUM> that is folded in the zigzag shape.

Although the unit cells may have the same size as illustrated in <FIG>, the present invention is not limited thereto. For example, the unit cells may have sizes different from each other. <FIG> illustrates a shape in which the unit cells <NUM> and <NUM> have sizes that decrease upward in phases.

When the unit cells decrease in size in phases, as illustrated in <FIG>, the electrode assembly <NUM> may have a stepped shape as a whole. When the electrode assembly <NUM> has the stepped shape, the electrode assembly <NUM> having various shapes may be realized. Furthermore, in this case, the secondary battery may be maximized in space utilization.

Referring to <FIG>, a method for manufacturing the electrode assembly <NUM> while stacking the separator sheet <NUM> in the zigzag shape may be performed as follows. The separator sheet <NUM> may be folded in a left direction L with respect to the drawing, and then, the first unit cell <NUM> may be stacked on the separator sheet <NUM> (A). Thereafter, the separator sheet <NUM> may be folded in a right direction R, and then, the second unit cell <NUM> may be stacked on the separator sheet <NUM> (B).

When the above-described processes in which the first unit cell <NUM> and the second unit cell <NUM> are disposed between the separator sheet <NUM> while folding the separator sheet <NUM> in the zigzag shape is repeatedly performed in the above-described manner, the stacked type electrode assembly <NUM> may be manufactured. The electrode assembly <NUM> having the zigzag shape or the method for manufacturing the electrode assembly <NUM> having the zigzag shape may be the electrode assembly <NUM> or the method for manufacturing the electrode <NUM>, in which productivity is capable of being significantly improved.

In the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, as described above, the separator sheet <NUM> may be folded in the zigzag shape, and the unit cells <NUM> and <NUM> are disposed between the folded separator sheets <NUM>. Here, at least a portion of the unit cells <NUM> and <NUM> and at least a portion of the separator sheet <NUM> may be bonded to each other.

When the unit cells <NUM> and <NUM> and the separator sheet <NUM> are bonded to each other, a degree of alignment of the electrode assembly <NUM> may be improved in the stacked type electrode assembly <NUM>. That is, as illustrated in <FIG> and <FIG>, the unit cells may be prevented from being separated in place, and thus, the degree of alignment of the electrode assembly <NUM> may be significantly improved. Although an external impact or movement occurs, the alignment of the electrode assembly <NUM> may not be disturbed.

Referring to <FIG>, in the bonding of the unit cells <NUM> and <NUM> and the separator sheet <NUM>, particularly, in the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, may be bonded to each other. The bonding of the separator <NUM> and the separator sheet <NUM> may be thermal bonding through heating Q.

Here, the thermal bonding through the heating Q may be thermal bonding through heating performed in a temperature range of <NUM> to <NUM>. If the temperature is less than <NUM>, bonding strength may not be sufficiently manifested. If the temperature is greater than <NUM>, the separator may be deformed.

When the thermal bonding is performed, the separator sheet <NUM> and the separator <NUM>, which is provided in the unit cell, may be bonded to each other along a side surface of each of the electrodes <NUM> and <NUM> provided in the unit cells <NUM> and <NUM>. Also, the separator sheet <NUM> and the separator <NUM>, which is provided in the unit cell, may be bonded to each other along a circumference of each of the electrodes provided in the unit cells <NUM> and <NUM>.

As described above, since the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, are bonded to each other, the electrodes <NUM> and <NUM> provided in the unit cells may be sealed from the outside. This means that the electrode is isolated from the outside, or that the electrode is sealed from the outside.

At least one of the separator sheet <NUM> and the separator <NUM> provided in each of the unit cells <NUM> and <NUM> may be surface-treated through plasma discharge or corona discharge.

When a surface of a polymer material such as the separator or the separator sheet is treated by using plasmas or corona, the bonding strength may be improved. As a result, while the separator <NUM> and the separator sheet <NUM> are bonded to each other or sealed, a temperature for the bonding or the sealing may be reduced. According to the above-described method, the electrode assembly <NUM> may be improved in degree of alignment with low-cost and high-efficiency.

The electrode assembly <NUM> according to Embodiment <NUM> of the present invention has been described above. Hereinafter, a method for manufacturing the electrode assembly <NUM> will be described.

The method for manufacturing the electrode assembly <NUM> according to Embodiment <NUM> of the present invention comprises a preparation step, a unit cell arrangement step, and a bonding step.

Here, the preparation step may be a step of preparing unit cells <NUM> and <NUM> having a structure, in which the electrodes <NUM> and <NUM> and the separator <NUM> are alternately stacked, and the separator sheet <NUM>. In the preparation step, a process of bonding the electrodes <NUM> and <NUM> and the separator <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, to each other may be performed. Thus, each of the unit cells may be formed as one unit.

In he preparation step, the unit cells <NUM> and <NUM> comprising a first unit cell <NUM>, in which a first electrode <NUM>, a separator <NUM>, a second electrode <NUM>, a separator <NUM>, and a first electrode <NUM> are sequentially stacked, and a second unit cell <NUM>, in which a second electrode <NUM>, a separator <NUM>, a first electrode <NUM>, a separator <NUM>, and a second electrode <NUM> are sequentially stacked, are prepared.

In the unit cell arrangement step may be a step of repeatedly arranging the unit cells <NUM> and <NUM> between the separator sheet <NUM> that is folded in the zigzag shape. In the unit cell arrangement step, the first unit cell <NUM> and the second unit cell <NUM> are repeatedly disposed and alternately stacked between the separator sheet <NUM> that is folded in the zigzag shape.

The bonding step may be a step of bonding at least a portion of the unit cells <NUM> and <NUM> to at least a portion of the separator sheet <NUM>. Particularly, the bonding step may be a step of bonding the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, to each other.

The bonding may be performed by heating the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>. When the bonding is performed, the separator sheet <NUM> and the separator <NUM> which is provided in the unit cell, may be bonded to each other along a side surface of each of the electrodes <NUM> and <NUM> provided in the unit cells <NUM> and <NUM>. Alternatively, the separator sheet <NUM> and the separator <NUM> which is provided in the unit cell, may be bonded to each other along a circumference of each of the electrodes provided in the unit cells.

Here, the bonding through heating may be performed at a temperature range of <NUM> to <NUM>. If the temperature is less than <NUM>, bonding strength may not be sufficiently manifested. If the temperature is greater than <NUM>, the separator may be deformed.

As described above, when the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, are bonded to each other, the electrodes provided in the unit cells may be sealed from the outside.

The method for manufacturing the electrode assembly <NUM> according to Embodiment <NUM> of the present invention may further comprise a surface treating step of performing surface treatment on at least one of the separator <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, through plasma discharge or corona discharge before the bonding step.

When the plasma treating or corona treating is performed, a surface of a polymer material such as the separator <NUM> or the separator sheet <NUM> may be improved in bonding strength. Thus, the process of manufacturing the electrode assembly <NUM> may be more efficiently and effectively performed.

<FIG> is a perspective view illustrating an electrode assembly according to Embodiment <NUM> of the present invention.

An electrode assembly according to Embodiment <NUM> may be similar to that according to Embodiment <NUM>. However, Embodiment <NUM> is different from Embodiment <NUM> in structure and manner in which the unit cell and the separator sheet are bonded to each other.

For reference, the same (equivalent) component as that according to the foregoing embodiment is given by the same (equivalent) reference number, and thus, their detailed description will be omitted.

Hereinafter, the electrode assembly according to Embodiment <NUM> of the present invention will be described with reference to <FIG>.

The electrode assembly <NUM> according to Embodiment <NUM> of the present invention may comprise a separator sheet <NUM> and unit cells <NUM> and <NUM>. The separator sheet <NUM> may be folded in a zigzag shape, and the unit cells may be repeatedly disposed between the separator sheet <NUM> that is folded in the zigzag.

Here, at least a portion of the unit cells <NUM> and <NUM> and at least a portion of the separator sheet <NUM> may be bonded to each other.

Particularly, in the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, the separator sheet <NUM> and the electrodes <NUM> and <NUM> which are provided in the unit cell, may be bonded to each other. The bonding may be performed though heating and pressing P. The heating and pressing P may be performed on the separator sheet <NUM> covering the electrodes <NUM> and <NUM> of the unit cell by using a heat press. As a result, at least a portion of the unit cells <NUM> and <NUM> and at least a portion of the separator sheet <NUM> may be bonded to each other.

Also, the bonding through the pressing P may be performed at a pressure range of <NUM> kgf/cm<NUM> to <NUM> kgf/cm<NUM>. When the pressure is greater than <NUM> kgf/cm<NUM>, a portion of the electrode may be efficiently performed. Also, when the pressure is greater than <NUM> kgf/cm<NUM>, the electrode or the separator may be damaged or deformed.

In the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, a portion of the outermost electrode T of the electrodes which are provided in the unit cell and a portion of the separator sheet <NUM>, may be bonded to each other. <FIG> illustrates a state in which the heating and the pressing P are performed on a portion Z of an area of the electrode.

When a portion of the electrode which are provided in the unit cell and a portion of the separator sheet <NUM>, are bonded to each other, bonding strength on an interface between the electrode and the separator sheet may have a value ranging from <NUM> gf/<NUM> to <NUM> gf/<NUM> with respect to the negative electrode/the separator. When the bonding strength is less than <NUM> gf/<NUM>, there is a possibility of occurrence of an alignment problem on the battery manufacturing process (various battery manufacturing steps). When the bonding strength is greater than <NUM> gf/<NUM>, it is difficult to wet an electrolyte into the cell.

When the electrode and the separator sheet <NUM> are bonded to each other on the portion Z of the area, the wetting of the electrode assembly <NUM> may be prevented from being deteriorated. When the electrode is bonded to the entire surface of the separator sheet <NUM>, the wetting of the electrode assembly <NUM> may be significantly deteriorated.

Thus, in the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, the degree of alignment of the electrode assembly <NUM> may be significantly improved while preventing the wetting of the electrode assembly <NUM> from being deteriorated.

The method for manufacturing the electrode assembly <NUM> according to Embodiment <NUM> of the present invention is similar to that for manufacturing the electrode assembly <NUM> according to Embodiment <NUM> of the present invention. However, there is a difference in the bonding step.

Particularly, according to the method for manufacturing the electrode assembly <NUM> according to Embodiment <NUM> of the present invention, the bonding step is performed in a manner in which the electrodes <NUM> and <NUM> and the separator sheet <NUM>, which are provided in each of the unit cells <NUM> and <NUM>, are bonded to each other. The bonding may be performed by heating and pressing P the electrode and the separator sheet <NUM>, which are provided in the unit cell. Also, in this process, only a portion of the outermost electrode T and only a portion of the separator sheet <NUM> may be bonded to each other.

Claim 1:
An electrode assembly comprising:
a separator sheet (<NUM>) folded in a zigzag shape; and
a unit cell (<NUM>, <NUM>) having a structure in which an electrode (<NUM>, <NUM>) and a separator (<NUM>) are alternately stacked,
the unit cell (<NUM>, <NUM>) being repeatedly disposed between the separator sheet (<NUM>) that is folded in a zigzag shape, and
at least a portion of the unit cell (<NUM>, <NUM>) and at least a portion of the separator sheet (<NUM>) are bonded to each other,
characterized in that the separator sheet (<NUM>) and the separator (<NUM>) which is provided in the unit cell (<NUM>, <NUM>), are bonded to each other.