Patent Description:
In the manufacture of a battery module including battery cells, the use of a cylindrical battery cell increases an empty space between adjacent battery cells, resulting in low energy density.

Additionally, when a cooling plate is interposed between battery cells for the purpose of cooling, the contact area between the battery cell and the cooling plate is narrow due to the shape of the side of the cylindrical battery cell, resulting in low cooling efficiency.

It is possible to increase the contact area a little bit by bringing the bottom surfaces of the cylindrical battery cells and the cooling plate into contact, but in this case, it takes a long time to transfer heat generated from the center of the battery cell to the bottom, resulting in inefficient cooling.

When the battery cell is manufactured in the shape of a hexagonal prism, it is possible to remove or minimize an empty space between battery cells. To manufacture the hexagonal prism-shaped battery cell, it is desirable to receive a hexagonal prism-shaped electrode assembly in a hexagonal prism-shaped cell case since energy density increases and cooling efficiency is improved through the cell case.

However, in case that the hexagonal prism-shaped electrode assembly is manufactured using the conventional electrode including an electrode active material continuously loaded on an electrode current collector, when bending the electrode, the electrode active material is also bent at the edge of the hexagonal prism where the electrode is bent, and a cracking or peeling phenomenon occurs in the electrode active material, resulting in degradation of the battery cell and the battery module.

Accordingly, there is a need for the development of technology for preventing the damage and/or separation of the electrode active material in the manufacture of the battery cell in the shape of a hexagonal prism.

<CIT> discloses an electrode coil, and its housing being prismatic in shape. <CIT> and <CIT> disclose an electrode assembly having a bending shape.

The present disclosure is designed to solve the above-described problem, and therefore the present disclosure is directed to providing a battery cell in the shape of a hexagonal prism to increase the energy density when packing battery cells to manufacture a battery module.

The present disclosure is further directed to providing a hexagonal prism-shaped electrode assembly used to manufacture a hexagonal prism-shaped battery cell, having a structure for preventing the electrode active material from being damaged and/or separated at the edge of the hexagonal prism.

However, the technical problem to solve is not limited to the above-described problems, and other problems not mentioned herein will be clearly understood by those skilled in the art from the following detailed description.

To achieve the above-described object, a battery cell as defined in the appended set of claims includes an electrode assembly having a hollow structure with a hexagonal prism-shaped hole at a center, wherein an exterior of the electrode assembly is in a shape of a hexagonal prism, and a cell case in which the electrode assembly is received, wherein an exterior of the cell case is in a shape of a hexagonal prism.

The electrode assembly includes a first electrode including a first electrode current collector and a first electrode active material block coated discontinuously at predetermined intervals on the first electrode current collector, a second electrode including a second electrode current collector and a second electrode active material block coated discontinuously at predetermined intervals on the second electrode current collector, and a separator interposed between the first electrode and the second electrode.

The first electrode may be bent at each first uncoated region between adjacent first electrode active material blocks, and the second electrode may be bent at each second uncoated region between adjacent second electrode active material blocks.

As the first electrode active material block and the second electrode active material block are farther away from a center of a cross section of the electrode assembly, the first electrode active material block and the second electrode active material block may be longer.

The separator may be interposed between an outermost surface of the electrode assembly and an inner surface of the cell case.

To achieve the above-described object, a method for manufacturing a battery cell according to an embodiment of the present disclosure includes preparing a first electrode by forming a first electrode active material block discontinuously at predetermined intervals on at least one surface of a first electrode current collector, preparing a second electrode by forming a second electrode active material block discontinuously at predetermined intervals on at least one surface of a second electrode current collector, forming a stack structure including the first electrode, the second electrode and a separator interposed the first electrode and the second electrode, winding the stack structure so that an exterior of an electrode assembly is in a shape of a hexagonal prism, and receiving the wound electrode assembly in a case.

When six first electrode active material blocks form a group in a sequential order from a start point of the winding, lengths of first electrode active material blocks belonging to a same group may be equal, and first electrode active material blocks belonging to a group that is farther away from the start point of the winding may be longer.

When six second electrode active material blocks form a group in a sequential order from the start point of the winding, lengths of second electrode active material blocks belonging to a same group may be equal, and second electrode active material blocks belonging to a group that is farther away from the start point of the winding may be longer.

The step of winding the stack structure may include bending the stack structure with respect to a first uncoated region between the first electrode active material blocks discontinuously formed and a second uncoated region between the second electrode active material blocks.

To achieve the above-described object, a battery module according to an embodiment of the present disclosure includes a cell assembly including a plurality of battery cells according to an embodiment of the present disclosure, and a cooling plate interposed between opposing surfaces of adjacent battery cells.

According to an aspect of the present disclosure, as a battery module is manufactured by packing hexagonal prism-shaped battery cells, the energy density of the battery module increases.

According to another aspect of the present disclosure, as an electrode assembly used to manufacture a hexagonal prism-shaped battery cell is manufactured in the shape of a hexagonal prism, damage and/or separation of the electrode active material at the edge of the hexagonal prism is prevented.

The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the following detailed description, serve to provide a further understanding of the technical features of the present disclosure. However, the present disclosure is not to be construed as being limited to the drawings.

Prior to the description, the terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, and should be interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the embodiments described herein and illustrations shown in the drawings are just a most preferred embodiment of the present disclosure, but not intended to fully describe the technical aspects of the present disclosure, so it should be understood that other equivalents and modifications could be made thereto at the time of filing the application.

First, referring to <FIG> and <FIG>, a battery module and a battery cell <NUM> according to an embodiment of the present disclosure will be described.

<FIG> is a plane view showing the battery module according to an embodiment of the present disclosure, and <FIG> is a diagram showing the battery cell according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, the battery module according to an embodiment of the present disclosure includes a plurality of battery cells <NUM> and at least one cooling plate <NUM>.

The battery cell <NUM> is in the shape of an approximately hexagonal prism, and accordingly it has an approximately regular hexagonal shape when viewed from the top.

As the battery cell <NUM> according to an embodiment of the present disclosure is in the shape of a hexagonal prism, it is possible to remove or minimize en empty space between adjacent battery cells <NUM> when packing the plurality of battery cells <NUM>.

That is, each of the plurality of battery cells <NUM> of the battery module has six sides, and it is possible to pack such that all the six sides of one battery cell <NUM> are in contact with adjacent battery cells <NUM>. Accordingly, the manufacture of the battery module using the hexagonal prism-shaped battery cell <NUM> according to the present disclosure is very advantageous in terms of energy density.

The cooling plate <NUM> may be interposed between opposing surfaces of adjacent battery cells <NUM>, and may be made of a metal material for efficient heat transfer. The cooling plate <NUM> may extend from one side of the battery module to the other side, and may be bent to conform the shape of the battery cell <NUM> having an approximately regular hexagonal shape when viewed on the plane.

That is, the cooling plate <NUM> is in surface-to-surface contact with the side of the battery cell <NUM>, and is bent at a location corresponding to the edge on the side of the battery cell <NUM> to maximize the contact area between the cooling plate <NUM> and the battery cell <NUM>.

Subsequently, referring to <FIG> with <FIG>, the schematic structure of the battery cell <NUM> according to an embodiment of the present disclosure will be described.

<FIG> is a diagram showing an electrode assembly that is applied to the battery cell according to an embodiment of the present disclosure.

Referring to <FIG> with <FIG>, the battery cell <NUM> includes an electrode assembly <NUM> and a cell case <NUM> in which the electrode assembly <NUM> is received.

As the battery cell <NUM> according to the present disclosure is in the shape of an approximately hexagonal prism as described above, the cell case <NUM> is also in the shape of an approximately hexagonal prism for such a shape, and has an empty internal space for receiving the electrode assembly <NUM>. Additionally, the electrode assembly <NUM> has a size that matches the size of the cell case <NUM>, and is in the shape of an approximately hexagonal prism in the same way as the cell case <NUM>.

As described above, the battery cell <NUM> according to an embodiment of the present disclosure include the hexagonal prism-shaped cell case <NUM> and the hexagonal prism-shaped electrode assembly <NUM> that is received in the cell case <NUM>. As the electrode assembly <NUM> is in the shape of a hexagonal prism, it is possible to maximize the volume of the electrode assembly <NUM> received in the cell case <NUM>, and as a consequence, the energy density of the battery cell <NUM>.

The electrode assembly <NUM> has a hollow structure having a hole H in the shape of an approximately hexagonal prism passing therethrough from the upper surface to the lower surface at the center. The hollow structure is formed by winding a stack structure including a first electrode <NUM>, a second electrode <NUM> and a separator <NUM> interposed between the first electrode <NUM> and the second electrode <NUM> into the shape of a hexagonal prism.

The cell case <NUM> may be made of a metal material to maintain the shape and ensure the strength, and in this case, an additional separator <NUM> may be wound on the outermost of the electrode assembly <NUM> to prevent a short circuit caused by the contact between the electrodes <NUM>, <NUM> and the cell case <NUM>.

In the present disclosure, the first electrode <NUM> may be a positive electrode and the second electrode <NUM> may be a negative electrode, and on the contrary, the first electrode <NUM> may be a negative electrode and the second electrode <NUM> may be a positive electrode.

Subsequently, referring to <FIG> and <FIG>, the detailed structure of the electrode assembly <NUM> applied to the battery cell <NUM> according to an embodiment of the present disclosure and its manufacturing method will be described.

<FIG> is a plane view showing the electrode assembly shown in <FIG>, and <FIG> is an enlarged view of section E in <FIG>.

Referring to <FIG> and <FIG>, the electrode assembly <NUM> includes the first electrode <NUM>, the second electrode <NUM> and the separator <NUM> interposed between the first electrode <NUM> and the second electrode <NUM>. Additionally, the electrode assembly <NUM> may further include the additional separator <NUM> wound on the outermost as described above.

The electrode assembly <NUM> has an approximately regular hexagonal shape on the basis of the plane view seen from the top, and the regular hexagonal shape is obtained by bending the stack structure formed by stacking the electrodes <NUM>, <NUM> and the separator <NUM> at predetermined intervals along the lengthwise direction. That is, in the electrode assembly <NUM>, the stack structure is bent at the angle of approximately <NUM>° toward the center C of the winding at predetermined intervals along the lengthwise direction.

The first electrode <NUM> includes a first electrode current collector 12a and a first electrode active material block 12b formed by a first electrode active material coated on at least one surface of the first electrode current collector 12a. The first electrode active material block 12b is coated discontinuously at predetermined intervals along the lengthwise direction of the first electrode current collector 12a. Accordingly, there is a first uncoated region F1, or a region in which the first electrode active material is not coated, between neighboring first electrode active material blocks 12b.

When winding the stack structure, bending occurs at the first uncoated region F1. That is, the first uncoated region F <NUM> corresponds to the edge of the hexagonal prism in the hexagonal prism-shaped electrode assembly <NUM>.

Likewise, the second electrode <NUM> includes a second electrode current collector 13a and a second electrode active material block 13b formed by a second electrode active material coated on at least one surface of the second electrode current collector 13a. The second electrode active material block 13b is coated discontinuously at predetermined intervals along the lengthwise direction of the second electrode current collector 13a. Accordingly, there is a second uncoated region F2, or a region in which the second electrode active material is not coated, between neighboring second electrode active material blocks 13b.

When winding the stack structure, bending occurs at the second uncoated region F2. That is, the second uncoated region F2 corresponds to the edge of the hexagonal prism in the hexagonal prism-shaped electrode assembly <NUM>.

As described above, the electrode assembly <NUM> is in the shape of a hexagonal prism by bending the uncoated regions F <NUM>, F2 of the first electrode <NUM> and the second electrode <NUM> of the stack structure, and bending does not occur on the electrode active material blocks 12b, 13b, thereby preventing the damage and separation of the electrode active material.

When winding the stack structure including the first electrode/the separator/the second electrode stacked in a sequential order such that it is bent toward the center of winding at predetermined intervals to form electrode assembly in the shape of a hexagonal prism, if the electrode active material exists at the region in which bending occurs, damage such as cracks may occur in the electrode active material or at least parts of the electrode active material may be separated.

To prevent this problem, the present disclosure does not continuously coat the electrode active material on the electrode current collector, and instead, discontinuously coats the electrode active material to form the uncoated region at predetermined intervals, and bends the stack structure at the uncoated region, so that the uncoated region becomes the edge of the hexagonal prism.

The first electrode current collector 12a may be a positive electrode current collector and the second electrode current collector 13a may be a negative electrode current collector, and on the contrary, the first electrode current collector 12a may be a negative electrode current collector and the second electrode current collector 13a may be a positive electrode current collector.

Likewise, the first electrode active material block 12b may be a positive electrode active material block and the second electrode active material block 13b may be a negative electrode active material block, and on the contrary, the first electrode active material block 12b may be a negative electrode active material block and the second electrode active material block 13b may be a positive electrode active material block.

Subsequently, referring to <FIG>, a method for manufacturing the battery cell <NUM> according to an embodiment of the present disclosure will be described.

<FIG> is a diagram showing a process of manufacturing the battery cell <NUM> according to an embodiment of the present disclosure. Additionally, <FIG> is a diagram showing an unfolded first electrode in the electrode assembly that is applied to the present disclosure, <FIG> is a diagram showing an unfolded second electrode in the electrode assembly that is applied to the present disclosure, and <FIG> is a diagram showing a process of winding the stack structure including the separator, the first electrode and the second electrode.

First, referring to <FIG>, the method for manufacturing a battery cell according to an embodiment of the present disclosure includes preparing the first electrode <NUM>; preparing the second electrode <NUM>; forming a stack structure including the first electrode <NUM>, the second electrode <NUM> and the separator <NUM> interposed between; winding the stack structure; and a casing step of receiving the electrode assembly <NUM> in the case <NUM>.

Referring to <FIG>, in the step of preparing the first electrode, a first electrode active material is discontinuously coated on one or two surfaces of the first electrode current collector 12a to form a plurality of first electrode active material blocks 12b.

The plurality of first electrode active material blocks 12b may be grouped to form a group for each six first electrode active material blocks 12b in a sequential order from one side of the lengthwise direction of the first electrode current collector 12a (where winding starts) to the other side. In this case, the first electrode active material blocks 12b belonging to the same group are formed with equal length. Additionally, the first electrode active material blocks 12b belonging to a group that is farther away from the start point of the winding are longer.

For example, when the first electrode active material blocks 12b are grouped into N groups, the length A2 of the first electrode active material blocks 12b belonging to a second group G2 is longer than the length A1 of the first electrode active material blocks 12b belonging to a first group G1, and the length AN of the first electrode active material blocks 12b belonging to an Nth group GN is longest.

This is because in the electrode assembly <NUM>, six first electrode active material blocks 12b of the first group form an innermost hexagonal prism, six first electrode active material blocks 12b of the second group form a hexagonal prism that surrounds the innermost hexagonal prism, and six first electrode active material blocks 12b of the Nth group form an outermost hexagonal prism.

The distances D1, D2, DN between neighboring first electrode active material blocks 12b may be equal within the same group, and may be different between different groups. That is, a group that is farther away from the start point of the winding may have a wider uncoated region F1. For example, the width D2 of the uncoated region F1 formed between the first electrode active material blocks 12b belonging to the second group G2 may be larger than the width D1 of the uncoated region F1 formed between the first electrode active material blocks 12b belonging to the first group G1, and the width DN of the uncoated region F1 formed between the first electrode active material blocks 12b belonging to the Nth group GN may be largest.

Referring to <FIG>, in the step of preparing the second electrode, the second electrode active material is discontinuously coated on one or two surfaces of the second electrode current collector 13a to form a plurality of second electrode active material blocks 13b.

The plurality of second electrode active material blocks 13b may be grouped to form a group for each six second electrode active material blocks in a sequential order from one side of the lengthwise direction of the second electrode current collector 13a (where winding starts) to the other side. In this case, the second electrode active material blocks 13b belonging to the same group are formed with equal length. Additionally, the second electrode active material blocks 13b belonging to a group that is farther away from the start point of the winding are longer.

For example, when the second electrode active material blocks 13b are grouped into N groups, the length B2 of the second electrode active material blocks 13b belonging to a second group G'<NUM> is larger than the length B <NUM> of the second electrode active material block 13b belonging to a first group G'<NUM>, and the length BN of the second electrode active material blocks 13b belonging to an Nth group G'N is largest.

This is because in the electrode assembly <NUM>, six second electrode active material blocks 13b of the first group form an innermost hexagonal prism, six second electrode active material blocks 13b of the second group form a hexagonal prism that surrounds the innermost hexagonal prism, and six second electrode active material blocks 13b of the Nth group form an outermost hexagonal prism.

The distances D1, D2, DN between neighboring second electrode active material blocks 13b may be equal within the same group, and may be different between different groups. That is, a group that is farther away from the start point of the winding may have a wider uncoated region F2. For example, the width D2 of the uncoated region F2 formed between the second electrode active material blocks 13b belonging to the second group G'<NUM> may be larger than the width D1 of the uncoated region F2 formed between the second electrode active material blocks 13b belonging to the first group G'<NUM>, and the width DN of the uncoated region F2 formed between the second electrode active material blocks 13b belonging to the Nth group G'N is largest.

In the step of forming the stack structure, the first electrode <NUM>/the separator <NUM>/the second electrode <NUM> are stacked in a sequential order to form the stack structure having the separator <NUM> interposed between the first electrode <NUM> and the second electrode <NUM>.

The step of forming the stack structure may further include placing the additional separator <NUM> on the outer surface of the first electrode <NUM> and/or on the outer surface of the second electrode <NUM>. That is, the stack structure prepared through the step of forming the stack structure may have a sequential stack of the separator <NUM>/the first electrode <NUM>/the separator <NUM>/the second electrode <NUM>/the separator <NUM>, or a sequential stack of the first electrode <NUM>/the separator <NUM>/the second electrode <NUM>/the separator <NUM>, or a sequential stack of the separator <NUM>/the first electrode <NUM>/the separator <NUM>/the second electrode <NUM>.

Referring to <FIG>, in the step of winding the stack structure, the stack structure is wound in the direction of the arrow such that the first electrode <NUM> forms an innermost layer. As opposed to <FIG>, when the separator <NUM> is placed on the outermost of the stack structure, the step of winding the stack structure corresponds to the step of winding the stack structure in the direction of the arrow such that the separator <NUM> forms an innermost layer.

In the step of winding the stack structure, the stack structure is wound in the direction of the arrow shown in <FIG>, and the electrode assembly <NUM> (see <FIG>) is formed in the shape of an approximately hexagonal prism by stacking such that the electrode current collectors 12a, 13a are bent at the uncoated regions F1, F2 shown in <FIG> and <FIG>.

In the casing step, the electrode assembly <NUM> (see <FIG>) in the shape of an approximately hexagonal prism through the winding step is received in the hexagonal prism-shaped cell case <NUM> (see <FIG>).

The method may further include the step of winding the separator <NUM> on the outer surface of the electrode assembly <NUM> between the winding step and the casing step. That is, the separator <NUM> may be or may not be disposed on the outermost of the stack structure as described above, and when the separator <NUM> is not disposed on the outermost of the stack structure, the second electrode <NUM> is disposed at the outermost of the electrode assembly <NUM> completed by winding the stack structure.

When the second electrode <NUM> is disposed at the outermost of the electrode assembly <NUM>, the second electrode <NUM> may come into contact with the inner surface of the cell case <NUM>, and as a consequence, a short circuit may occur. Accordingly, it is necessary to wind the separator <NUM> on the outer surface of the electrode assembly <NUM> to prevent a short circuit.

Claim 1:
A battery cell (<NUM>), comprising:
an electrode assembly (<NUM>) having a hollow structure with a hexagonal prism-shaped hole (H) at a center, wherein an exterior of the electrode assembly is in a shape of a hexagonal prism; and
a cell case (<NUM>) in which the electrode assembly is received, wherein an exterior of the cell case is in a shape of a hexagonal prism,
wherein the electrode assembly includes:
a first electrode (<NUM>) including a first electrode current collector (12a) and a first electrode active material block (12a) coated discontinuously at predetermined intervals on the first electrode current collector;
a second electrode (<NUM>) including a second electrode current collector (13a) and a second electrode active material block (13b) coated discontinuously at predetermined intervals on the second electrode current collector; and
a separator (<NUM>) interposed between the first electrode (<NUM>) and the second electrode (<NUM>).