Patent Description:
The present invention relates to an electrode slurry coating apparatus and method including a pressure regulating member.

With the increase in technology development and demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries are widely used as an energy source for various electronic products as well as various mobile devices because of their high energy density and high operating voltage and excellent storage and lifetime characteristics.

In addition, the secondary battery has a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is accommodated in a battery case in a state impregnated with an electrolyte solution. The positive electrode and the negative electrode are coated with an electrode slurry containing an active material on a current collector formed of, for example, a metal foil, such as aluminum or copper.

<FIG> is a schematic diagram showing a process of discharging an electrode slurry on a current collector layer using a conventional electrode slurry coating apparatus. Referring to <FIG>, the electrode slurry coating apparatus has a structure in which an electrode slurry discharge flow path <NUM> for discharging an electrode slurry <NUM> through a slit formed on an interface between two dies is formed. In addition, the slurry supply flow path <NUM> is fluidly connected to the electrode slurry discharge flow path <NUM>, through which the electrode slurry <NUM> is supplied. A current collector layer <NUM> formed of a metal foil passes the front of the electrode slurry discharge flow path <NUM> through a conveyor (not shown) driven by a rotating roller <NUM>. The discharged electrode slurry is discharged on the current collector layer <NUM>. The structure shown in <FIG> is a structure in which a coated part <NUM> and a non-coated part <NUM> are repeated on the current collector layer <NUM>. The coated part <NUM> is a region where the electrode slurry is coated, and the non-coated part <NUM> is a region where the electrode slurry is not coated. The electrode slurry coating apparatus repeats the discharge and interruption of the electrode slurry <NUM>. However, when the discharge of the interrupted electrode slurry is resumed, excessive load is taken into the electrode slurry discharge flow path <NUM>, and thus excessive electrode slurry is discharged. As a result, in the case of the front <NUM>(a) of the coated part <NUM>, the coating becomes thick as the excess electrode slurry is discharged, and in the case of the rear <NUM>(b) of the coated part <NUM>, the coating rapidly becomes thin as the discharge of the electrode slurry is interrupted. As such, when a conventional electrode slurry coating apparatus is used, it is difficult to uniformly perform the electrode coating of a structure in which the coated part <NUM> and the non-coated part <NUM> are repeated.

<CIT>, <CIT>, <CIT>, and <CIT> disclose a slot die coater for coating electrode active material on a current collector.

The present invention was invented to solve the above problems, and an object of the present invention is to provide an electrode slurry coating apparatus and method including a pressure regulating member.

The present invention provides an electrode slurry coating apparatus as defined in the appended set of claims. An electrode slurry coating apparatus according to the present invention includes: an electrode slurry discharge flow path configured to discharge an electrode slurry through a slit formed on an interface between first and second dies; an electrode slurry storage tank configured to be fluidly connected to the electrode slurry discharge flow path and store the electrode slurry therein at a static pressure condition; and a static pressure opening and closing valve configured to be located on a flow path on which the electrode slurry discharge flow path is fluidly connected to the electrode slurry storage tank, wherein an opening or closing of the static pressure opening and closing valve is determined according to a difference between a pressure of the electrode slurry discharge flow path and an internal pressure of the electrode slurry storage tank.

In a specific example, the electrode slurry discharge flow path and the electrode slurry storage tank face each other in a state in which the static pressure opening and closing valve is interposed therebetween.

In one example, the static pressure opening and closing valve is configured to open when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank.

According to the invention, the static pressure opening and closing valve includes a shielding member supported by an elastic force of an elastic body, and the shielding member is configured to open if a force of pressurizing the shielding member by the pressure of the electrode slurry discharge flow path exceeds a predetermined reference value.

In another disclosed but not claimed specific example, the electrode slurry coating apparatus further includes a pressure sensor configured to measure an internal pressure of the electrode slurry discharge flow path, and the static pressure opening and closing valve is configured to open if a pressure measured by the pressure sensor exceeds a predetermined reference value.

In one example, the electrode slurry storage tank further includes an electrode slurry outlet flow path configured to discharge the stored electrode slurry if the internal pressure of the electrode slurry storage tank exceeds a predetermined reference value.

In a specific example, the electrode slurry outlet flow path is fluidly connected to the electrode slurry discharge flow path.

In one example, the electrode slurry discharged through the electrode slurry discharge flow path is discharged on a current collector layer which is moved by a conveyor.

In another example, the electrode slurry coating apparatus further includes a discharge control pump configured to control a discharge amount of the electrode slurry through the electrode slurry discharge flow path.

In one example, the electrode slurry coating apparatus further includes a discharge blocking member configured to control an opening and closing of the electrode slurry discharge flow path.

In a specific example, the discharge blocking member is formed at an end of the electrode slurry discharge flow path.

Further, the present invention provides a method, which is defined in the appended set of claims, for coating an electrode slurry by using the above described electrode slurry coating apparatus. A method for coating an electrode slurry by using the above mentioned electrode slurry coating apparatus according to the present invention comprises:
discharging an electrode slurry on a current collector layer through a slit-shaped electrode slurry discharge flow path formed on an interface between first and second dies, wherein during the discharging the electrode slurry, a process of starting a discharge of the electrode slurry and a process of interrupting the discharge of the electrode slurry are repeated at regular intervals, and wherein a pressure of the electrode slurry discharged is maintained constant by a pressure adjusting member formed on the slit-shaped electrode slurry discharge flow path.

In one example, the pressure adjusting member includes: an electrode slurry storage tank configured to be fluidly connected to the electrode slurry discharge flow path and store the electrode slurry therein at a static pressure condition; and a static pressure opening and closing valve configured to be located on a flow path on which the electrode slurry discharge flow path is fluidly connected to the electrode slurry storage tank, wherein an opening or closing of the static pressure opening and closing valve is determined according to a difference between a pressure of the electrode slurry discharge flow path and an internal pressure of the electrode slurry storage tank.

In a specific example, the static pressure opening and closing valve is configured to open when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank.

The electrode slurry coating apparatus and the method according to the present invention include a pressure regulating member, so that the electrode slurry can be discharged at a constant pressure even when the coated part and the non-coated part are repeated on the current collector layer.

The present invention relates to an electrode slurry coating apparatus, and in one example, the electrode slurry coating apparatus includes:.

The electrode slurry discharge flow path has a slit-shaped structure and refers to a flow path through which the electrode slurry is discharged through the interface between the blocks in a structure in which two or more blocks are engaged.

The electrode slurry coating apparatus allows the electrode slurry to be continuously coated on the current collector which moves in one direction. When coating the electrode slurry on a current collector layer using the electrode slurry coating apparatus, the discharge can be performed in a form in which a coated part and a non-coated part are repeated in a machine direction (MD). In this case, the electrode slurry coating apparatus should repeat the discharge of the electrode slurry and interruption of the discharge. However, when the coating of the electrode slurry interrupted in the electrode slurry coating apparatus is resumed, excessive load is taken to the electrode slurry discharge flow path. When an excessive load is applied to the electrode slurry discharge flow path, the electrode slurry is excessively discharged to the coating start portion of the coated part. The excessively discharged electrode slurry causes a phenomenon that the loading amount of the electrode slurry becomes uneven, which leads to the defect of products. In the present invention, by including a pressure adjusting member for maintaining a pressure of the electrode slurry discharge flow path constant, these problems are solved. The pressure adjusting member has a structure including an electrode slurry storage tank and a static pressure opening and closing valve described above.

In one example, the electrode slurry discharge flow path and the electrode slurry storage tank face each other in a state in which the static pressure opening and closing valve is interposed therebetween. The electrode slurry storage tank according to the present invention is directly connected to an electrode slurry discharge flow path in a state in which a static pressure opening and closing valve is interposed. If a fluid connection line of a predetermined distance or more is formed, there is a limit in that it is difficult to immediately respond to the pressure change of the electrode slurry discharge flow path. Therefore, in the present invention, the static pressure opening and closing valve becomes part of the structure in which the electrode slurry discharge flow path is formed. Thus, in the present invention, it is possible to perform immediate pressure control by reflecting the pressure difference between the electrode slurry discharge flow path and the electrode slurry storage tank.

In one embodiment, the static pressure opening and closing valve has an open structure when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank. When the coating of the electrode slurry interrupted in the electrode slurry coating apparatus is resumed, excessive load is taken to the electrode slurry discharge flow path, thereby discharging a lot of electrode slurry. In the present invention, excessive loads in the electrode slurry discharge flow path can be efficiently resolved. That is, if an excessive load is applied to the electrode slurry discharge flow path, the static pressure opening and closing valve is configured to open, and a part of the electrode slurry which exists in the electrode slurry discharge flow path is leaked toward the electrode slurry storage tank. This solves the load taken to the electrode slurry discharge flow path.

According to the invention, the static pressure opening and closing valve includes a shielding member supported by an elastic force of an elastic body, and the shielding member is configured to open if a force of pressurizing the shielding member by the pressure of the electrode slurry discharge flow path exceeds a predetermined reference value. In this case, the static pressure opening and closing valve includes a shielding member supported by a spring or a hinge structure with a spring. Thus, the present invention can control the opening and closing of the static pressure opening and closing valve in a non-powered manner and does not require a sensor for measuring the internal pressure of the electrode slurry discharge flow path.

In another disclosed but not claimed specific embodiment, the electrode slurry coating apparatus according to the present disclosure further includes a sensor for measuring the internal pressure of the electrode slurry discharge flow path, and when the pressure measured by the pressure sensor exceeds a predetermined reference value, the static pressure opening and closing valve is configured to open. In this case, a pressure sensor for measuring the pressure of the electrode slurry discharge flow path is formed, thereby controlling the operation of the static pressure opening and closing valve.

In one specific example, the electrode slurry storage tank further includes an electrode slurry outlet flow path configured to discharge the stored electrode slurry if the internal pressure of the electrode slurry storage tank exceeds a predetermined reference value. The electrode slurry storage tank has a predetermined structure, which maintains an internal pressure of, for example, a <NUM> kgf level, in a state where the electrode slurry is filled. When the pressure of the electrode slurry discharge flow path exceeds <NUM> kgf, the static pressure opening and closing valve is configured to open. As the static pressure opening and closing valve is configured to open, a part of the electrode slurry located in the electrode slurry discharge flow path is moved to the electrode slurry storage tank. Thus, the pressure of the electrode slurry discharge flow path is reduced. However, the internal pressure of the electrode slurry storage tank increases due to the inflowing electrode slurry. In order to solve this, the electrode slurry storage tank may have a structure in which an electrode slurry outlet flow path is formed on the lower one side. The above-described static pressure opening and closing valve may be further formed on the electrode slurry outlet flow path.

In a disclosed but not claimed example, a pressure sensor for measuring the internal pressure may be formed in a electrode slurry storage tank, and if the pressure measured by the pressure sensor exceeds the reference value, the electrode slurry outlet flow path may be opened. Alternatively, according to the invention an opening and closing valve of a structure including a shielding member supported by elastic force of an elastic body is located on the electrode slurry outlet flow path. The opening and closing valve with such an elastic body is advantageous in that a controller for opening and closing a separate sensor and valve is not required.

In one embodiment, the electrode slurry outlet flow path is fluidly connected to the electrode slurry discharge flow path. It is also possible to discard the electrode slurry discharged from the electrode slurry storage tank. However, it is possible to reuse the discharged electrode slurry by allowing the electrode slurry outlet flow path to be fluidly connected to the electrode slurry discharge flow path.

In one example, the electrode slurry discharged through the electrode slurry discharge flow path is discharged on a current collector layer which is moved by a conveyor. The current collector layer may be formed of an aluminum foil or a copper foil. For example, the current collector layer moves along the conveyor in one direction, and the electrode slurry coating apparatus discharges the electrode slurry so that the coated part and the non-coated part are repeated on the current collector layer.

In one specific embodiment, the electrode slurry coating apparatus further incudes a discharge control pump for controlling the discharge amount of the electrode slurry through the electrode slurry discharge flow path. The discharge control pump repeatedly performs a process of pressurization to discharge the electrode slurry and a process of interrupting the pressurization. Thus, the electrode slurry coating apparatus according to the present invention discharges the electrode slurry so that the coated part and the non-coated part are repeated on the current collector layer.

In another specific embodiment, the electrode slurry coating apparatus further includes a discharge blocking member for controlling opening and closing of the electrode slurry discharge flow path. The discharge blocking member is formed in the form of a bar that blocks, for example, a slit of the electrode slurry discharge flow path. When the discharge blocking member closes the electrode slurry discharge flow path, the discharge of the electrode slurry by the electrode slurry coating apparatus is discontinued. Thus, the electrode slurry coating apparatus according to the present invention discharges the electrode slurry so that the coated part and the non-coated part are repeated on the current collector layer. For example, the discharge blocking member is formed at an end of the electrode slurry discharge flow path.

The present invention also provides an electrode slurry coating method using the electrode slurry coating apparatus described above. In one example, a method for coating an electrode slurry according to the present invention includes a step of discharging an electrode slurry on a current collector layer through a slit-shaped electrode slurry discharge flow path formed on an interface between first and second dies.

In the step of discharging the electrode slurry, a process of starting a discharge of the electrode slurry and a process of interrupting the discharge of the electrode slurry are repeated at regular intervals, and
a pressure of the electrode slurry discharged is maintained constant by a pressure adjusting member formed on the slit-shaped electrode slurry discharge flow path.

In the present invention, by repeating a step of starting the discharge of the electrode slurry and a step of interrupting the discharge of the electrode slurry, it is possible to coat the electrode slurry on the current collector layer, with a pattern in which the coated part and the non-coated part are repeated in MD direction. In this case, the electrode slurry coating method according to the present invention should repeat the discharge of the electrode slurry and interruption of the discharge. However, when the coating the electrode slurry, if the discharge of the electrode slurry is resumed, excessive load is taken to the electrode slurry discharge flow path. The excessive load taken to the electrode slurry discharge flow path causes the electrode slurry to be excessively discharged to the coating start portion of the coated part. In the present invention, by including a pressure adjusting member for maintaining a pressure of the electrode slurry discharge flow path constant, these problems are solved.

In one specific embodiment, the static pressure opening and closing valve has an open structure when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank. When the coating of the electrode slurry interrupted in the electrode slurry coating method is resumed, excessive load is taken to the electrode slurry discharge flow path, thereby discharging a lot of electrode slurry. In the present invention, excessive loads in the electrode slurry discharge flow path can be efficiently resolved. That is, if an excessive load is applied to the electrode slurry discharge flow path, the static pressure opening and closing valve is configured to open, and a part of the electrode slurry which exists in the electrode slurry discharge flow path is leaked toward the electrode slurry storage tank. This solves the load taken to the electrode slurry discharge flow path.

According to the invention, the static pressure opening and closing valve includes a shielding member supported by an elastic force of an elastic body, and the shielding member is configured to open if a force of pressurizing the shielding member by the pressure of the electrode slurry discharge flow path exceeds a predetermined reference value. If the static pressure opening and closing valve includes a shielding member supported by elastic force of an elastic body, the static pressure opening and closing valve includes a shielding member supported by a spring or a hinge structure with a spring. As such, the present invention can control the opening and closing of the static pressure opening and closing valve in a non-powered manner and does not require a sensor for measuring the internal pressure of the electrode slurry discharge flow path.

In another disclosed but not claimed specific embodiment, the electrode slurry coating method according to the present disclosure further includes a sensor for measuring the internal pressure of the electrode slurry discharge flow path, and when the pressure measured by the pressure sensor exceeds a predetermined reference value, the static pressure opening and closing valve is configured to open.

In one example, the electrode slurry storage tank further includes an electrode slurry outlet flow path configured to discharge the stored electrode slurry if the internal pressure of the electrode slurry storage tank exceeds a predetermined reference value. Further, the electrode slurry outlet flow path is fluidly connected to the electrode slurry discharge flow path. It is also possible to discard the electrode slurry discharged from the electrode slurry storage tank. However, it is possible to reuse the discharged electrode slurry by allowing the electrode slurry outlet flow path to be fluidly connected to the electrode slurry discharge flow path.

In the present invention, a description of the electrode slurry coating apparatus mentioned above is also applicable to the electrode slurry coating method, and a redundant description about this is omitted here.

Hereinafter, the present invention will be described in more detail through drawings and examples.

<FIG> is a schematic diagram showing a process of discharging an electrode slurry on a current collector layer using an electrode slurry coating apparatus according to an embodiment of the present invention. Referring to <FIG>, the electrode slurry coating apparatus has a structure in which an electrode slurry discharge flow path <NUM> for discharging an electrode slurry <NUM> through a slit formed on an interface between two dies is formed. In addition, the slurry supply flow path <NUM> is fluidly connected to the slurry discharge flow path <NUM>, through which the electrode slurry <NUM> is supplied. A current collector layer <NUM> formed of a metal foil passes the front of the electrode slurry discharge flow path <NUM> through a conveyor (not shown) driven by a rotating roller <NUM>. The discharged electrode slurry is discharged on the current collector layer <NUM>. <FIG> shows a structure in which a coated part <NUM> and a non-coated part <NUM> are repeated on the current collector layer <NUM>, and the electrode active material coating apparatus repeats the discharge of the electrode slurry and interruption of the discharge. However, when the discharge of the interrupted electrode slurry is resumed, excessive load is taken into the electrode slurry discharge flow path <NUM>, and thus excessive electrode slurry may be discharged.

The present invention provides a pressure adjusting member for maintaining the load or pressure applied to the electrode slurry discharge flow path <NUM> constant. The pressure adjusting member includes an electrode slurry storage tank <NUM> where the electrode slurry <NUM> is filled and which maintain the internal pressure at a static pressure condition, and a static pressure opening and closing valve <NUM> where whether the static pressure opening and closing valve <NUM> is configured to open is determined according to a difference between the pressure of the electrode slurry discharge flow path <NUM> and the internal pressure of the electrode slurry storage tank <NUM>. The electrode slurry storage tank <NUM> can be fluidly connected to the electrode slurry discharge flow path <NUM> and stores the electrode slurry <NUM> at a static pressure condition. Further, the static pressure opening and closing valve <NUM> is located on the flow path where the electrode slurry discharge flow path <NUM> is fluidly connected to the electrode slurry storage tank <NUM>, and whether the static pressure opening and closing valve <NUM> is configured to open is determined according to the difference between the pressure of the electrode slurry discharge flow path <NUM> and the internal pressure of the electrode slurry storage tank <NUM>.

Specifically, the electrode slurry discharge flow path <NUM> and the electrode slurry storage tank <NUM> face each other in a state in which the static pressure opening and closing valve <NUM> is interposed therebetween. Further, the static pressure opening and closing valve <NUM> is configured to open when the pressure of the electrode slurry discharge flow path <NUM> is greater than the internal pressure of the electrode slurry storage tank <NUM>.

<FIG> and <FIG> are schematic diagrams illustrating an opening and closing process of a pressure adjusting member according to one embodiment of the present invention. Referring to <FIG>, the pressure adjusting member according to the present invention includes an electrode slurry storage tank <NUM> with an open upper surface, a static pressure opening and closing valve <NUM> which covers the upper surface of the electrode slurry storage tank <NUM>, and an electrode slurry outlet flow path <NUM> formed at lower one side of the electrode slurry storage tank <NUM>. The static pressure opening and closing valve <NUM> includes a plate-shaped shielding member supported by elastic force of an elastic body (e.g., a spring). Through this, the static pressure opening and closing valve <NUM> is configured to open when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank <NUM>.

Referring to <FIG>, the static pressure opening and closing valve <NUM> is configured to open when the pressure of the electrode slurry discharge flow path is greater than the internal pressure of the electrode slurry storage tank <NUM>. The electrode slurry storage tank <NUM> maintains an internal pressure of <NUM> kgf, for example, in a state where the electrode slurry <NUM> is filled. When the pressure of the electrode slurry discharge flow path exceeds <NUM> kgf, the pressure of the electrode slurry discharge flow path is transmitted to push and open the static pressure opening and closing valve <NUM>. As the static pressure opening and closing valve <NUM> is configured to open, a part of the electrode slurry located in the electrode slurry discharge flow path is moved to the electrode slurry storage tank <NUM>. Thus, the pressure of the electrode slurry discharge flow path is reduced.

Further, the electrode slurry outlet flow path <NUM> is formed at lower one side of the electrode slurry storage tank <NUM>. An outlet pump <NUM> is formed on the electrode slurry outlet flow path <NUM>. As mentioned above, the internal pressure of the electrode slurry storage tank <NUM> increases due to an electrode slurry which flows in as the static pressure opening and closing valve is configured to open. If the internal pressure of the electrode slurry storage tank <NUM> increases, part of the internal electrode slurry is discharged to the electrode slurry outlet flow path <NUM> by the outlet pump <NUM>. It is also possible to form a separate static pressure opening and closing valve instead of the outlet pump <NUM>.

<FIG> is a schematic diagram illustrating an electrode slurry coating process according to an electrode slurry coating method according to one embodiment of the present invention. Referring to <FIG>, the method of coating an electrode slurry according to the present invention includes a step of discharging an electrode slurry <NUM> through a slit-shaped electrode slurry discharge flow path <NUM> formed on the interface between two dies. The electrode slurry <NUM> is supplied through the electrode slurry supply flow path <NUM>. Further, in the step of discharging the electrode slurry <NUM>, a process of starting the discharge of the electrode slurry <NUM> and a process of interrupting the discharge of the electrode slurry <NUM> are repeated. At this time, the pressure of the electrode slurry <NUM> discharged is maintained constant by the pressure adjusting member formed on the slit-shaped electrode slurry discharge flow path <NUM>. The pressure adjusting member includes an electrode slurry storage tank <NUM> with an open upper surface, a static pressure opening and closing valve <NUM> which covers the upper surface of the electrode slurry storage tank <NUM>, and an electrode slurry outlet flow path <NUM> formed at lower one side of the electrode slurry storage tank <NUM>. The current collector layer <NUM> is located on a conveyor moving by a rotating roller <NUM>. The electrode slurry is coated on the current collector layer <NUM> so that the coated part <NUM> and the non-coated part <NUM> are repeated at regular intervals.

Further, the electrode slurry <NUM> is filled in the electrode slurry storage tank <NUM> to thereby maintain a constant pressure. When the pressure of the electrode slurry discharge flow path <NUM> increases, the static pressure opening and closing valve <NUM> is configured to open, and part of the electrode slurry <NUM> existing in the electrode slurry discharge flow path <NUM> flows into the electrode slurry storage tank <NUM>, thereby controlling pressure. When the pressure in the electrode slurry storage tank <NUM> exceeds a predetermined level, part of the electrode slurry <NUM> filled inside is discharged to the electrode slurry outlet flow path <NUM> via the outlet pump <NUM>.

In some cases, the electrode slurry discharged to the electrode slurry outlet flow path <NUM> is returned to the electrode slurry discharge flow path <NUM> or the electrode slurry supply flow path <NUM>.

Claim 1:
An electrode slurry coating apparatus, comprising:
an electrode slurry discharge flow path (<NUM>) configured to discharge an electrode slurry (<NUM>) through a slit formed on an interface between first and second dies;
an electrode slurry storage tank (<NUM>) configured to be fluidly connected to the electrode slurry discharge flow path (<NUM>) and store the electrode slurry (<NUM>) therein at a static pressure condition; and
a static pressure opening and closing valve (<NUM>) configured to be located on a flow path on which the electrode slurry discharge flow path (<NUM>) is fluidly connected to the electrode slurry storage tank (<NUM>),
wherein an opening or closing of the static pressure opening and closing valve (<NUM>) is determined according to a difference between a pressure of the electrode slurry discharge flow path (<NUM>) and an internal pressure of the electrode slurry storage tank (<NUM>),
characterized in that
the static pressure opening and closing valve (<NUM>) includes a shielding member supported by an elastic force of an elastic body, and
the shielding member is configured to open if a force of pressurizing the shielding member by the pressure of the electrode slurry discharge flow path (<NUM>) exceeds a predetermined reference value.