Patent Description:
With the increasing technology development and the growing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing, and a secondary battery essentially includes an electrode assembly which is a power generation element. The electrode assembly includes a positive electrode, a separator and a negative electrode stacked at least once, and the positive electrode and the negative electrode are manufactured by coating and drying a positive electrode active material slurry and a negative electrode active material slurry on a current collector made of an aluminum foil and a current collector made of a copper foil, respectively. In general, the secondary battery includes lithium containing cobalt oxide (LiCoO<NUM>) of layered crystal structure, lithium containing manganese oxide, for example, LiMnO<NUM> of layered crystal structure and LiMn<NUM>O<NUM> of spinel crystal structure, and lithium containing nickel oxide (LiNiO<NUM>) for the positive electrode active material. Additionally, a carbon based material is primarily used for the negative electrode active material, and recently, with the growing demand for high energy lithium secondary batteries, the carbon based material may be mixed with a silicon based material or a silicon oxide based material having the effective capacity that is at least <NUM> times larger than the carbon based material. For the uniform charge/discharge characteristics of the secondary battery, it is necessary to uniformly coat the positive electrode active material slurry and the negative electrode active material slurry on the current collector, and slot die coaters have been used to do so.

<FIG> shows an example of a coating method using a conventional slot die coater. <FIG> is a cross-sectional view of <FIG>, taken along the line II-II', showing the slot die coater along the MD direction (the movement direction of the current collector).

Referring to <FIG> and <FIG>, an electrode manufacturing method using the slot die coater <NUM> includes coating an electrode active material slurry delivered from the slot die coater <NUM> on a current collector <NUM> transported by a coating roll <NUM>. The electrode active material slurry delivered from the slot die coater <NUM> is coated over one surface of the current collector <NUM> to form an electrode active material layer. The slot die coater <NUM> includes two die blocks <NUM>, <NUM> and has a slot <NUM> between the two die blocks <NUM>, <NUM>. A manifold <NUM> accommodates the electrode active material slurry supplied from a feeder (not shown), and the electrode active material slurry is delivered through the exit port <NUM> in communication with the slot <NUM> to form the electrode active material layer. The reference numbers <NUM> and <NUM> indicate the die lips at the front ends of the die blocks <NUM>, <NUM>, respectively, and the reference number <NUM> is a land portion.

The coating width of the electrode active material layer coated on the current collector <NUM> is determined by the width of the slot <NUM>. When it is necessary to change the coating width, various coating widths may be realized by changing a shim plate <NUM> that determines the internal space of the manifold <NUM> and the width of the slot <NUM>.

<FIG> is a diagram showing the conventional shim plate.

The shim plate <NUM> is disposed on the manifold <NUM> in the die block <NUM>. The shim plate <NUM> is a sheet-shaped member having a thickness defining a slot gap. Typically, as shown in <FIG>, the end of the shim plate <NUM> is aligned with the die lip <NUM>. The reference number <NUM> is an injection port through which the electrode active material slurry is supplied from the feeder, and in most cases, the injection port is formed at the bottom center of the manifold <NUM>.

<FIG> is a diagram showing the conventional shim plate offset.

The shim offset O control is performed to move back the end of the shim plate <NUM> from the die lip <NUM> at the front end of the die block <NUM>. The shim offset O control is essential for the coating width process capability in view of the slurry delivery pressure or the like, but it is difficult to precisely control the shim offset O and ensure reproducibility.

<FIG> is a diagram showing the conventional shim.

As a variation of the shim plate <NUM> of <FIG>, a shim <NUM>' controls the widthwise loading profile by blocking the passage to the land portion <NUM> from the manifold <NUM> of the die block <NUM>. The shim <NUM>' further includes a portion <NUM> at the central area of the shim plate <NUM>. However, there is a limitation on loading profile control by the conventional shim <NUM>'.

Since it is difficult to change the shape of the manifold <NUM> of the die block <NUM> once it is initially formed, it will be desirable to solve the problems such as shim offset control or loading profile control by improving the shim plate <NUM>.

The present disclosure is designed to solve the above-described problem, and therefore the present disclosure is directed to providing a slot die coater including an improved shim plate.

However, the technical problem to be solved by the present disclosure is not limited to the above-described problems, and these and other problems will be clearly understood by those skilled in the art from the following description.

The invention is described by the claims.

To solve the above-described problem, a slot die coater of the present invention includes a lower die block and an upper die block; a shim plate interposed between the lower die block and the upper die block to form a slot therebetween; and a manifold disposed in the lower die block, the manifold accommodating a coating solution, wherein the coating solution is delivered and coated on a substrate through an exit port in communication with the slot, and wherein the shim plate includes a plate-shaped member having an open portion which is cut in at least an area to determine a coating width of a coating layer coated on the substrate, and a structure protruding from the plate-shaped member and inserted into the manifold.

The structure may be integral to the plate-shaped member.

At rear of the manifold and in front of the manifold, a lower surface of the upper die block and an upper surface of the shim plate may be coupled to each other without a gap, and an upper surface of the lower die block and a lower surface of the shim plate may be coupled to each other without a gap.

An upper surface of the shim plate may be flat and the structure may protrude in part of a lower surface of the shim plate.

The plate-shaped member may include a first part which serves as a base and at least two second parts extended from the first part, and the second part may be connected to a same side of the first part and extended in a same direction.

The structure may be a side structure which is inserted into two ends of the manifold in an area of contact with the manifold at two ends of the plate-shaped member to ensure positional reproducibility of the shim plate.

The side structure may have a same shape as a cross-sectional shape of the manifold to fit into the manifold including a bottom of the manifold.

In example, the plate-shaped member may include a first part which serves as a base and at least two second parts extended from the first part, the second part may be connected to a same side of the first part and extended in a same direction, and the side structure may be extended and protruded downward from an inner sidewall of the second part close to the manifold.

The structure may be an extended partition structure which is extended from a center of the plate-shaped member to the exit port and is thicker than the plate-shaped member to have a thickness that is inserted into the manifold.

Specifically, the plate-shaped member may include a first part which serves as a base and at least two second parts extended from the first part, the second part may be connected to a same side of the first part and extended in a same direction, and the partition structure may be extended from a center of the first part in a same direction as the second part and may be extended and protruded downward.

The structure is a branch structure which splits the coating solution coming out of an injection port at a bottom of the manifold into two branches.

The branch structure may include an extended portion extended downward along a sidewall of the manifold and a bottom portion connected to the extended portion and placed along the bottom of the manifold.

The branch structure may further include a plurality of shim injection ports in the bottom portion.

The plurality of shim injection ports may have an increasing diameter as it goes from center to side.

In another example, the plate-shaped member may include a first part which serves as a base and at least two second parts extended from the first part, the second part may be connected to a same side of the first part and extended in a same direction, the extended portion may be extended and protruded downward from the first part, and the bottom portion may be integrally connected to a lower end of the extended portion.

In this instance, the slot die coater may further include a plurality of shim injection ports in the bottom portion, the shim injection ports having an increasing diameter as it goes from center to side, and the shim injection ports may be circular in shape.

According to an aspect of the present disclosure, it is possible to ensure the shim offset reproducibility when assembling the shim plate into the slot die coater.

According to another aspect of the present disclosure, it is easy to control the widthwise loading profile.

It is difficult to change the shape of the manifold once it is initially formed. According to still another aspect of the present disclosure, it is possible to reconstruct the manifold area of the slot die coater through the shape of the shim plate without changing the manifold.

As such, according to the present disclosure, it is possible to form the coating solution flow structure that is impossible for the conventional shim plate which is a sheet-shaped member and improve the coating width and loading process capability.

The present disclosure provides the slot die coater including the shim plate including the new functional structure above and below the plate-shaped member, not simply a sheet-shaped member. Preferably, the new functional structure is included below the plate-shaped member to make use of the manifold structure below the shim plate.

Since the corresponding functional structure is mainly related to the manifold, it is possible to ensure the positional reproducibility of the shim plate itself or reconstruct the flow structure in the manifold to form the flow structure that is impossible for the conventional sheet-shaped member and improve the coating width and the quality of the loading process capability.

It is possible to stably form the electrode active material layer using the slot die coater according to the present disclosure.

The accompanying drawings illustrate an exemplary embodiment of the present disclosure and together with the following detailed description, serve to provide a further understanding of the technical aspect of the present disclosure, and thus, the present disclosure is not construed as being limited to the drawings.

Hereinafter, an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspect 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 in the drawings are just an exemplary embodiment of the present disclosure and do not fully describe the technical aspect of the present disclosure, so it should be understood that a variety of other equivalents and modifications could have been made thereto at the time of filing the patent application.

Like reference numerals indicate like elements. Additionally, in the drawings, the elements are depicted in exaggerated thickness, proportion and dimension for effective description of the technical subject matter.

A slot die coater of the present disclosure is a device having a slot to coat a coating solution on a substrate through the slot. In the following description, the 'substrate' is a current collector and the 'coating solution' is an electrode active material slurry. However, the scope of protection of the present disclosure is not necessarily limited thereto. For example, the substrate may be a porous support for a separator and the coating solution may be an organic matter. That is, where thin film coating is required, any type of substrate and coating solution may be used. In this disclosure, 'front' indicates an exit port side and 'rear' indicates the opposite side.

The present disclosure is aimed at ensuring the shim offset reproducibility of the slot die coater. The present disclosure reconstructs a manifold area of the slot die coater through the shape of a shim plate to form a flow structure that is impossible for the conventional shim plate which is a sheet-shaped member and improve the coating width and loading process capability.

The present disclosure suggests a shim plate including a new functional structure above and below a plate-shaped member, rather than simply a sheet-shaped member. Preferably, the new functional structure is included below the plate-shaped member to make use of the manifold structure below the shim plate.

Since the corresponding functional structure is mainly related to the manifold, it is possible to ensure the positional reproducibility of the shim plate itself or reconstruct the flow structure in the manifold to form the flow structure that is impossible for the conventional shim plate which is a sheet-shaped member and improve the coating width and the quality of the loading process capability.

<FIG> is a cross-sectional view of the slot die coater according to an embodiment of the present disclosure.

The slot die coater <NUM> of the present disclosure includes a lower die block <NUM> and an upper die block <NUM>. A shim plate <NUM> is present between the lower die block <NUM> and the upper die block <NUM> to form a slot <NUM> therebetween.

The lower die block <NUM> includes a manifold <NUM>. The manifold <NUM> accommodates a coating solution <NUM>. The slot die coater <NUM> delivers and coats the coating solution <NUM> on a substrate <NUM> through an exit port 101a in communication with the slot <NUM>.

In addition to the lower die block <NUM> and the upper die block <NUM>, the slot die coater <NUM> may further include another die block. The shim plate <NUM> may be included every two die blocks to form two or more slots. The lower die block <NUM> and the upper die block <NUM> are named on the basis of the shim plate <NUM>, and in the case of a larger number of die blocks, the lower die block <NUM> or the upper die block <NUM> may become an intermediate die block.

Meanwhile, in <FIG>, the slot die coater <NUM> is installed such that the delivery direction (X direction) of the coating solution or the electrode active material slurry is almost horizontal (almost ± <NUM>°). However, the present disclosure is not limited thereto, and for example, the slot die coater <NUM> may be a vertical die type such that the delivery direction of the electrode active material slurry is the upward direction (Y direction).

The slot <NUM> is formed in an area of contact between the two die blocks <NUM>, <NUM>. Here, the shim plate <NUM> is present between the die blocks <NUM>, <NUM> to form a gap that becomes the slot <NUM> corresponding to a passage along which the coating solution <NUM> may flow. The thickness of the shim plate <NUM> determines the vertical width (Y direction, a slot gap) of the slot <NUM>.

The shim plate <NUM> is characterized by including a plate-shaped member having an open portion that is cut in at least an area to determine the coating width of the coating layer on the substrate <NUM>, and a structure that protrudes from the plate-shaped member and is inserted into the manifold <NUM>, and the structure may be integral to the plate-shaped member. The structures will be described in more detail below.

The shim plate <NUM> has the open portion that is cut in an area, and may be present at the remaining area except one side among the edges of the facing surface of each of the die blocks <NUM>, <NUM>. Accordingly, the exit port 101a through which the coating solution <NUM> exits is present between the die lips <NUM>, <NUM> respectively at the front ends of the die blocks <NUM>, <NUM>. The exit port 101a may be formed by the gap between the die lips <NUM>, <NUM>.

For reference, the shim plate <NUM> acts as a gasket to prevent the coating solution <NUM> from leaking through the gap between the two die blocks <NUM>, <NUM> except the area in which the exit port 101a is present, and is preferably made of a material having sealability.

According to the description, any one of the two die blocks <NUM>, <NUM> includes the manifold <NUM> having a predetermined depth, and the manifold <NUM> is in communication with the slot <NUM>. In the invention, the manifold <NUM> is included in the lower die block <NUM>. Although not shown, the manifold <NUM> is connected to a coating solution feed chamber (not shown) installed outside with a feed pipe and is supplied with the coating solution <NUM>. When the manifold <NUM> is fully filled with the coating solution <NUM>, the flow of the coating solution <NUM> is guided along the slot <NUM> and leaves the exit port 101a.

At the rear of the manifold <NUM>, the lower surface of the upper die block <NUM> and the upper surface of the shim plate <NUM> may be coupled to each other without a gap, and the upper surface of the lower die block <NUM> and the lower surface of the shim plate <NUM> may be coupled to each other without a gap. Also in front of the manifold <NUM>, the lower surface of the upper die block <NUM> and the upper surface of the shim plate <NUM> may be coupled to each other without a gap, and the upper surface of the lower die block <NUM> and the lower surface of the shim plate <NUM> may be coupled to each other without a gap. Through this, the coating solution <NUM> flows only in the slot <NUM> defined by the shim plate <NUM>.

According to the slot die coater <NUM> having this configuration, while the substrate <NUM> to be coated is being moved by the rotation of a rotatable coating roll <NUM> disposed at the front side of the slot die coater <NUM>, the coating solution <NUM> may be delivered and continuously coated in contact with the surface of the substrate <NUM>. Alternatively, pattern coating may be intermittently formed on the substrate <NUM> by supplying the coating solution <NUM> and stopping the supply in an alternating manner.

Here, the shim plate <NUM> determines the coating width of the coating layer on the substrate <NUM>, and according to the present disclosure, is characterized by including the plate-shaped member and the structure. An embodiment of the structure may include those described with reference to <FIG> are diagrams for describing the shim plates according to various embodiments that may be included in the slot die coater of the present disclosure. The structure is intended to realize the above-mentioned functional structure and may come in three types as shown in <FIG>, <FIG> and <FIG>, and these structures may be used singly or in various combinations. For example, <FIG> shows a combination of the three structures.

The conventional shim plate is a sheet-shaped member and corresponds to a <NUM>-dimensional (2D) planar structure, while the present disclosure further includes a structure above and/or below the plate-shaped member that serves as the base of the shim plate, preferably extended into the manifold, and thus has a <NUM>-dimensional (3D) stereoscopic structure. In particular, the 3D stereoscopic structure is different from a 3D stereoscopic structure that is maintained during the action of a deformation force applied to parts of the shim plate of the 2D planar structure and returns to the 2D planar structure when the deformation force is removed. The 3D stereoscopic structure is formed by the shape of the shim plate itself, and there is no deformation of the shim plate before and after coupling the shim plate to the slot die coater.

The shim plate <NUM> may be made of plastics or metals, but the present disclosure is not limited thereto. The shim plate <NUM> may be, for example, a resin sheet of Teflon, polyester or the like, or a metal sheet of copper, aluminum or the like. The shim plate <NUM> may be coupled and fixed to at least one of the two die blocks <NUM>, <NUM>, for example, through a screw, but the present disclosure is not limited thereto.

First, <FIG> is a bottom perspective view showing an example of the shim plate that may be included in the slot die coater of the present disclosure. <FIG> is a perspective view of the shim plate of <FIG> and the lower die block. <FIG> is a side view of the lower die block equipped with the shim plate of <FIG>.

Referring to <FIG>, the shim plate <NUM> includes a plate-shaped member <NUM> including the open portion 130a that is cut in at least an area to determine the coating width of the coating layer on the substrate <NUM> and a side structure <NUM> that protrudes from the plate-shaped member <NUM> and is inserted into the manifold <NUM>. The upper surface of the shim plate <NUM> or the surface in contact with the upper die block <NUM> may be flat, and the side structure <NUM> may protrude from parts of the lower surface of the shim plate <NUM> or the surface in contact with the lower die block <NUM>.

The side structure <NUM> ensures the positional reproducibility of the shim plate <NUM> itself. The reference number <NUM> is an injection port through which the electrode active material slurry is supplied from a feeder and is present at the bottom center of the manifold <NUM>.

The side structure <NUM> may be inserted into two ends of the manifold <NUM> in an area of contact with the manifold <NUM> at two ends of the plate-shaped member <NUM>, thereby ensuring the positional reproducibility of the shim plate <NUM>. The side structure <NUM> may protrude from the plate-shaped member <NUM> and be inserted into the two ends of the manifold <NUM> in the area of contact with the manifold <NUM> at the two ends of the plate-shaped member <NUM>.

The plate-shaped member <NUM> may include a first part 132a that serves as the base and at least two second parts 132b extended from the first part 132a. The first part 132a is a part of the shim plate <NUM> that is placed at the rear side of the lower die block <NUM>. For the shim plate <NUM> disposed at the remaining area except one side among the edges of the facing surface of each of the upper die block <NUM> and the lower die block <NUM>, the number of second parts 132b is at least two. In this embodiment, two second parts 132b are shown by way of illustration. The open portion 130a is present between the two adjacent second parts 132b. As the number of second parts 132b increases, two or more coating layers may be formed side by side on the substrate <NUM>. That is, stripe pattern coating may be formed. The present disclosure is not limited by the number of second parts 132b.

The second part 132b is connected to the same side of the first part 132a and extended in the same direction. The second part 132b is a part of the shim plate <NUM> that is extended to the front side of the lower die block <NUM>. The side structure <NUM> is extended and protruded downward from the inner sidewall of the second part 132b close to the manifold <NUM>. The second part 132b and the side structure <NUM> may be integrally formed. That is, there is no gap or spacing between the second part 132b and the side structure <NUM>. Accordingly, it is possible to prevent the unnecessary flow of the coating solution between the side structure <NUM> and the second part 132b. For example, the plate-shaped member <NUM> is a <IMG>-shaped plate-shaped member and may have a similar shape to the conventional shim plate described in <FIG>. The shim plate <NUM> of the present disclosure includes the plate-shaped member <NUM> and further includes the side structure <NUM> that protrudes downward from the plate-shaped member <NUM> and is inserted into the manifold <NUM> below the shim plate <NUM> at the location close to two sidewalls (placed on two sides in the widthwise direction of the slot die coater) of the manifold <NUM>. With the side structure <NUM> inserted into the manifold <NUM>, the accuracy in the assembly of the shim plate <NUM> increases. Additionally, when it is designed such that the end of the shim plate <NUM> is offset from the die lip <NUM>, the shim plate <NUM> is always placed at the same location, and thus, the originally designed offset may be always maintained. Accordingly, it is possible to ensure the shim offset reproducibility when assembling the shim plate <NUM> into the slot die coater <NUM>.

The side structure <NUM> may have the same shape as the cross-sectional shape of the manifold <NUM> to fit into the manifold <NUM> including the bottom of the manifold <NUM> to fix the position and prevent the unnecessary flow of the coating solution near the side structure <NUM>. In an example, in case in which the manifold <NUM> is semi-circular in cross section, the side structure <NUM> may have a semi-circular shape to match it. In another example, in case in which the manifold <NUM> is trapezoidal in cross section, the side structure <NUM> may have a trapezoidal shape to match it.

The plate-shaped member <NUM> and the side structure <NUM> may be an integrally formed structure. That is, the side structure <NUM> is not formed by adding or attaching another member to the plate-shaped member <NUM>, and may be integrally formed when fabricating the shim plate <NUM>. The plate-shaped member <NUM> and the side structure <NUM> are seamlessly connected. Accordingly, the fabrication process is straightforward, there is no need to consider and manage the coupling strength between the plate-shaped member <NUM> and the side structure <NUM> to be considered in case in which the plate-shaped member <NUM> and the side structure <NUM> are separate structures, and it is structurally strong. In addition, it is possible to prevent the slurry from unnecessarily staying in between the plate-shaped member <NUM> and the side structure <NUM>.

<FIG> is a bottom perspective view showing another example of the shim plate that may be included in the slot die coater of the present disclosure. <FIG> is a perspective view of the shim plate of <FIG> and the lower die block.

The structure that will be described in <FIG> and <FIG> is a partition structure extended below the plate-shaped member.

Referring to <FIG> and <FIG>, the shim plate <NUM> includes the plate-shaped member <NUM> having the open portion 130a that is cut in at least an area to determine the coating width of the coating layer coated on the substrate <NUM>, and the partition structure <NUM> protruded from the plate-shaped member <NUM> and inserted into the manifold <NUM>. The partition structure <NUM> is extended from the center of the plate-shaped member <NUM> to the exit port 101a, and has a sufficient thickness to be inserted into the manifold <NUM>. In particular, the partition structure <NUM> is thicker than the plate-shaped member <NUM>. Compared to the shape of the conventional shim <NUM>' described with reference to <FIG>, the partition structure <NUM> is extended into the manifold <NUM> to have a predetermined thickness, and thus the partition structure <NUM> may be referred to as a reinforced shim.

In the same way as the description made with reference to <FIG>, the plate-shaped member <NUM> includes the first part 132a that serves as the base and the second parts 132b extended from the first part 132a. The partition structure <NUM> is extended from the center of the first part 132a in the same direction as the second parts 132b and is extended and protruded downward. The first part 132a and the partition structure <NUM> may be integrally formed. That is, there is no gap or spacing between the first part 132a and the partition structure <NUM>. Accordingly, it is possible to prevent the unnecessary flow of the coating solution between the partition structure <NUM> and the first part 132a.

In the conventional shim <NUM>', the shim plate <NUM> and the sheet-shaped portion <NUM> have the same thickness. That is, the upper surface or the lower surface of the shim <NUM>' is flat. The shim <NUM>' is simply used to change the flow of the slurry to control the loading quantity. By contrast, the partition structure <NUM> of the shim plate <NUM> of the present disclosure may be thicker than the plate-shaped member <NUM>, and may protrude from the plate-shaped member <NUM>, and accordingly have a larger mass. Accordingly, the partition structure <NUM> has higher strength and includes a step that is stuck in the step of the manifold <NUM>, and thus in case that the partition structure <NUM> is placed in a situation in which the partition structure <NUM> is subjected to a force in any direction, it is possible to prevent deformation or damage and fix the position. As described above, the partition structure <NUM> has higher structural strength.

The partition structure <NUM> provides the flow rate adjustment function to the shim plate <NUM>. The partition structure <NUM> may protrude toward the exit port 101a to the largest extent at the center as shown. With respect to the center of the partition structure <NUM>, the central flow channel may be narrower than the two side flow channels. Accordingly, the pressure at the center increases while the coating solution <NUM> passes through the shim plate <NUM>, and the coating solution <NUM> moves to the two sides along the partition structure <NUM>. The partition structure <NUM> may have a polygonal structure having slopes as shown, and may have a gently round structure, and the shape may be variously adjusted according to the properties of the coating solution and the process conditions. According to the shim plate <NUM> including the partition structure <NUM>, it is easy to control the widthwise loading profile.

The plate-shaped member <NUM> and the partition structure <NUM> may be an integrally formed structure. That is, the partition structure <NUM> is not formed by adding or attaching another member to the plate-shaped member <NUM>, and may be integrally formed when fabricating the shim plate <NUM>. The plate-shaped member <NUM> and the partition structure <NUM> are seamlessly connected. Accordingly, the fabrication process is straightforward, there is no need to consider and manage the coupling strength between the plate-shaped member <NUM> and the partition structure <NUM> to be considered in case in which the plate-shaped member <NUM> and the partition structure <NUM> are separate structures, and it is structurally strong. In addition, it is possible to prevent the slurry from unnecessarily staying in between the plate-shaped member <NUM> and the partition structure <NUM>.

<FIG> is a bottom perspective view showing another example of the shim plate that may be included in the slot die coater of the present disclosure, and <FIG> is a perspective view of the shim plate of <FIG> and the lower die block. The description that will be made in <FIG> and <FIG> corresponds to the entire flow channel reconstruction of the manifold.

Referring to <FIG> and <FIG>, the shim plate <NUM> includes the plate-shaped member <NUM> having the open portion 130a that is cut in at least an area to determine the coating width of the coating layer coated on the substrate <NUM>, and a branch structure <NUM> protruded from the plate-shaped member <NUM> and inserted into the manifold <NUM>. The branch structure <NUM> splits the coating solution coming out of the injection port <NUM> formed at the bottom of the manifold <NUM> into two branches.

As shown in <FIG>, in the conventional manifold <NUM>, the injection port <NUM> is present at the bottom center. Due to the position of the injection port <NUM>, in the conventional art, in many cases, loading at the center is high. In the present disclosure, to solve this problem, the branch structure <NUM> is extended into the manifold <NUM> and splits the coating solution coming out of the injection port <NUM> into two branches to guide the movement of the coating solution along the branch structure <NUM> to perform control to prevent the increase in loading at any one side.

The branch structure <NUM> includes an extended portion 138a extended downward along the sidewall of the manifold <NUM> and a bottom portion 138b connected to the extended portion 138a and placed along the bottom of the manifold <NUM>. The bottom portion 138b includes a plurality of shim injection ports 139a, 139b, 139c, 139d having an increasing diameter as it goes from center to side.

In the same way as description made with reference to <FIG>, the plate-shaped member <NUM> includes the first part 132a serving as the base and the second parts 132b extended from the first part 132a. The extended portion 138a may be extended and protruded downward from the first part 132a and the bottom portion 138b may be integrally connected to the lower end of the extended portion 138a. The shim injection ports 139a, 139b, 139c, 139d may be, for example, circular in shape.

The first part 132a and the extended portion 138a may be integrally formed. That is, there is no gap or spacing between the first part 132a and the extended portion 138a. Accordingly, it is possible to prevent the unnecessary flow of the coating solution between the extended portion 138a and the first part 132a.

It is possible to prevent the concentrated flow at the center close to the injection port <NUM> by guiding the movement of the coating solution from the existing injection port <NUM> to the new shim injection ports 139a, 139b, 139c, 139d. It is possible to reconstruct the flow channel through simple adjustment of the shim plate <NUM> without changing the structure of the manifold <NUM>, and fix the position of the shim plate <NUM> more firmly due to the branch structure <NUM> inserted into the manifold <NUM>.

It is difficult to change the shape of the manifold <NUM> once it is initially formed. According to the present disclosure, it is possible to reconstruct the manifold <NUM> area of the slot die coater <NUM> through the shim plate <NUM> including the branch structure <NUM> without changing the manifold <NUM>.

<FIG> shows the shim plate <NUM> including all the three structures <NUM>, <NUM>, <NUM> described above. The shim plate <NUM> may be formed by combining the side structure <NUM> of <FIG> with the branch structure <NUM> of <FIG>, or combining the side structure <NUM> of <FIG> with the partition structure <NUM> of <FIG>, or combining the partition structure <NUM> of <FIG> with the branch structure <NUM> of <FIG>, as necessary.

It is possible to stably form electrode active material layers using the slot die coater <NUM> and its variations. For example, the slot die coater <NUM> may be used to coat positive electrode active material slurries to manufacture positive electrodes of secondary batteries.

The positive electrode includes a current collector and a positive electrode active material layer on the surface of the current collector. The current collector may include electrically conductive materials, for example, Al and Cu, and a suitable one may be used according to the polarity of the current collector electrode known in the field of secondary batteries. The positive electrode active material layer may further include at least one of a plurality of positive electrode active material particles, a conductive material or a binder. Additionally, the positive electrode may further include various types of additives to supplement or improve the electrical and chemical properties.

The active material is not limited to a particular type and may include any type of active material that can be used for positive electrode active materials of lithium ion secondary batteries. Its non-limiting examples may include at least one of layered compounds or compounds with one or more transition metal substitution such as lithium manganese composite oxide (LiMn<NUM>O<NUM>, LiMnO<NUM>), lithium cobalt oxide (LiCoO<NUM>), lithium nickel oxide (LiNiO<NUM>); lithium manganese oxide of formula Li<NUM>+xMn<NUM>-xO<NUM> (x is <NUM> to <NUM>), LiMnO<NUM>, LiMn<NUM>O<NUM>, LiMnO<NUM>; lithium copper oxide (Li<NUM>CuO<NUM>); vanadium oxide, for example, LiV<NUM>O<NUM>, LiV<NUM>O<NUM>, V<NUM>O<NUM>, Cu<NUM>V<NUM>O<NUM>; Ni site lithium nickel oxide represented by formula LiNi<NUM>-xMxO<NUM> (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = <NUM> to <NUM>); lithium manganese composite oxide represented by formula LiMn<NUM>-xMxO<NUM> (M = Co, Ni, Fe, Cr, Zn or Ta, x = <NUM> to <NUM>) or Li<NUM>Mn<NUM>MO<NUM> (M = Fe, Co, Ni, Cu or Zn); LiMn<NUM>O<NUM> with partial substitution of alkali earth metal ion for Li in the formula; disulfide compounds; or Fe<NUM>(MoO<NUM>)<NUM>. In the present disclosure, the positive electrode may include a solid electrolyte material, for example, at least one of a polymer-based solid electrolyte, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

The conductive material may be typically added in an amount of <NUM> wt% to <NUM> wt% based on the total weight of the mixture including the active material. The conductive material is not limited to a particular type, and may include any material having conductive properties without causing any chemical change to the corresponding battery, for example, at least one selected from graphite, for example, natural graphite or artificial graphite; carbon black, for example, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers, for example, carbon fibers or metal fibers; metal powder, for example, carbon fluoride, aluminum and nickel powder; conductive whiskers, for example, zinc oxide and potassium titanate; conductive metal oxide, for example, titanium oxide; and conductive materials, for example, polyphenylene derivatives.

The binder is not limited to a particular type and may include any material which assists in binding the active material and the conductive material together and binding to the current collector, for example, polyvinylidene fluoride polyvinylalcohol, carboxymethylcellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylenepropylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluoro rubber and a variety of copolymers thereof. The binder may be typically included in the range of <NUM> wt% to <NUM> wt% or <NUM> wt% to <NUM> wt% based on <NUM> wt% of the electrode layer.

The slot die coater <NUM> of the present disclosure may be used to coat negative electrode active material slurries to manufacture negative electrodes of secondary batteries. The negative electrode includes a current collector and a negative electrode active material layer on the surface of the current collector. The negative electrode active material layer may further at least one of a plurality of negative electrode active material particles, a conductive material or a binder. Additionally, the negative electrode may further include a variety of additives to supplement or improve the electrical and chemical properties.

The negative electrode active material may include carbon materials, for example, graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotubes and carbon nanohorns, lithium metal materials, alloy-based materials, for example, silicon or tin alloy based materials, oxide-based materials, for example, Nb<NUM>O<NUM>, Li<NUM>Ti<NUM>O<NUM>, TiO<NUM>, or a composite thereof. For the details of the conductive material, the binder and the current collector of the negative electrode, reference may be made to the description of the positive electrode.

The active material slurry including the positive electrode active material or the negative electrode active material has very high viscosity. For example, the viscosity may be <NUM> cps or more. The viscosity of the active material slurry used to form electrodes of secondary batteries may be <NUM> cps to <NUM> cps. For example, the viscosity of the negative electrode active material slurry may be <NUM> cps to <NUM> cps. The viscosity of the positive electrode active material slurry may be <NUM> cps to <NUM> cps. Since it is necessary to coat the coating solution having the viscosity of <NUM> cps or more, the slot die coater <NUM> of the present disclosure is different in structure from devices for coating any other coating solution having lower viscosity, for example, an ordinary resin solution such as a photosensitive emulsion, a magnetic solution, an antireflection or antiglare solution, a solution for enlarging the field of view and a pigment solution for a color filter, and cannot be arrived at by design modification. Since the slot die coater <NUM> of the present disclosure is, for example, designed to coat the active material slurry comprising the active material having the average particle size of about <NUM>, its structure is different from those of devices for coating any other coating solution including no particles having the above-described particle size, and cannot be arrived at by design modification. The slot die coater <NUM> of the present disclosure is the optimal coater for the manufacture of electrodes.

While the present disclosure has been hereinabove described with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be apparent that a variety of changes and modifications may be made by those skilled in the art within the technical aspect of the present disclosure and the appended claims and their equivalent scope.

Claim 1:
A slot die coater (<NUM>), comprising:
a lower die block (<NUM>) and an upper die block (<NUM>);
a shim plate (<NUM>) interposed between the lower die block (<NUM>) and the upper die block (<NUM>) to form a slot therebetween; and
a manifold (<NUM>) disposed in the lower die block (<NUM>), the manifold (<NUM>) being configured to accommodate a coating solution (<NUM>),
wherein the coating solution (<NUM>) is configured to be delivered and coated on a substrate (<NUM>) through an exit port in communication with the slot, and
wherein the shim plate (<NUM>) includes a plate-shaped member (<NUM>) having an open portion which is cut in at least an area to determine a coating width of a coating layer coated on the substrate (<NUM>), and a structure protruding from the plate-shaped member (<NUM>) and inserted into the manifold (<NUM>),
characterized in that the structure is a branch structure (<NUM>) for splitting the coating solution (<NUM>) coming out of an injection port (<NUM>) at a bottom of the manifold (<NUM>) into two branches.