Patent Application
20230228486
The present invention relates to a vacuum drying apparatus for vacuum-drying an electrode in a roll-to-roll state and a vacuum drying method therefor.
More particularly, the present invention relates to a vacuum drying apparatus and a vacuum drying method capable of improving the wet performance of electrodes as well as drying electrodes with a high moisture content by performing evacuation to various vacuum pressures according to set processing conditions.
With developments in technology and increases in demand for mobile devices, the demand for secondary batteries is rapidly increasing. Among secondary batteries, lithium secondary batteries are widely used as an energy source for various electronic products as well as various mobile devices because they have high energy density and operating voltage and excellent preservation and life cycle characteristics.
Lithium secondary batteries are manufactured through an electrode process of coating a positive-electrode active material and a negative-electrode active material with a positive-electrode conductor foil and a negative-electrode conductor foil, which are current collector sheets, respectively, an assembly process including notching for forming an electrode tab in an uncoated region to which the active material of the electrode is not applied; lamination of laminating the electrode and a separator to produce an electrode assembly, packaging of stacking or folding the electrode assembly, packaging the electrode assembly in pouches or cans, and injecting electrolyte, and the like, and an activation process of charging or discharging the assembled battery to impart battery characteristics
Also, the electrode is transferred and processed in a so-called roll-to-roll state in which it is laid between an unwinder and a rewinder in the electrode manufacturing process or assembly process, etc. Such a roll-type electrode sheet has high hygroscopicity because a paste-like mixture composed of an active material, a conductive material, a binder, and the like is applied to a metal foil serving as a base material. Therefore, it is necessary to remove moisture during an electrode manufacturing process.
However, when an electrode is dried in an electrode roll state, a temperature difference occurs between the inside and outside of the roll, and thus it is difficult to uniformly dry the electrode. So, a method of vacuum-drying an electrode in a roll-to-roll state has been introduced.
Meanwhile, recently, electrodes in which it is difficult to express desired battery characteristics because the moisture of the electrodes is formed to be high depending on the composition of the active material, the size of particles constituting the active material, or the like have emerged. For example, positive electrodes coated with a high-nickel positive-electrode material introduced to increase battery capacity and reduce manufacturing cost or electrodes of an active material having a small particle size structure deviate from a desired moisture specification because they are vulnerable to external environments and have a high moisture absorption rate in the atmosphere.
However, conventional electrode vacuum drying apparatuses dried electrodes by evacuating a vacuum chamber to a low vacuum level of 1 Torr or more and thus had a limitation in removing moisture from the electrodes. In particular, in the case of electrodes with a high moisture content as described above, it was difficult to sufficiently remove moisture using such a vacuum drying apparatus for performing vacuum drying at a low vacuum level.
Furthermore, even if moisture was removed to some extent, the conventional low-vacuum drying apparatuses were insufficient to improve the wet performance of electrodes. The wet performance of an electrode refers to performance in which electrolyte can be impregnated by easily permeating into the active material of the electrode when the electrode assembly is packaged in a container and the electrolyte is injected into the container. Since the wet performance of such an electrode is further improved as the electrolyte is more easily impregnated into bubbles inside the electrode, it is necessary to properly form the bubbles for the electrolyte to be impregnated in the electrode. However, the conventional low-vacuum drying apparatuses have a limitation in improving the wet performance of an electrode, in particular, the wet performance of an electrode with a high moisture content.
In order to remove moisture from electrodes and improve the performance of electrodes, it may be assumed that the electrodes are dried by evacuating a vacuum chamber with a medium-vacuum device or a high-vacuum device. However, it is not easy to evacuate the vacuum chamber from a low vacuum level to a medium-high vacuum level through a single pipe due to the structure of the vacuum equipment or pipe, and the control thereof will also be very complicated. Also, when the vacuum chamber is evacuated directly to a high vacuum level, so-called vacuum damage in which the electrode is damaged by the vacuum may occur.
Meanwhile, when the electrode is continuously vacuum-dried in the vacuum chamber, foreign substances generated from the electrode may float in the vacuum chamber or remain in the chamber. When the vacuum drying is continued in the vacuum chamber, foreign substances may be attached to the electrode of the electrode roll that is subsequently introduced into the vacuum chamber, and thus the electrode may be contaminated in the vacuum chamber.
Based on this, it is desired to develop a vacuum drying technique capable of removing moisture from electrodes and improving the wet performance of electrodes without causing vacuum damage to the electrodes.
Also, it will be desirable to develop a vacuum drying technique capable of preventing electrode contamination by effectively removing foreign substances from the vacuum chamber.
Japanese Patent No. 5984643 (2016.9.6)
The present invention has been made to solve the above problems and is directed to providing an apparatus for vacuum-drying an electrode in a roll-to-roll state, which can efficiently remove moisture from the electrode and improve the wet performance of the electrode while preventing vacuum damage even when the electrode has a high moisture content.
Also, the present invention is directed to providing an apparatus for vacuum-drying an electrode in a roll-to-roll state, which can prevent contamination by foreign substances in a vacuum chamber.
Also, the present invention is directed to providing a method of vacuum-drying an electrode in a roll-to-roll state, which can efficiently remove moisture from the electrode and improve the wet performance of the electrode.
An apparatus for vacuum-drying an electrode in a roll-to-roll state of the present invention in order to solve the above problems includes a vacuum chamber in which an electrode is disposed in the roll-to-roll state and dried; a low-vacuum evacuation device connected to the vacuum chamber by a low-vacuum pipe and configured to evacuate the vacuum chamber to a low vacuum level; a medium-high-vacuum evacuation device connected to the vacuum chamber by a medium-high-vacuum pipe separate from the low-vacuum pipe and configured to evacuate the vacuum chamber to a medium vacuum level or a high vacuum level; and a control unit connected to the low-vacuum evacuation device and the medium-high-vacuum evacuation device and configured to regulate a vacuum level in the vacuum chamber stepwise to dry the electrode.
As an example, the low vacuum level may be a vacuum level ranging from 1 to 600 Torr, the medium vacuum level may be a vacuum level ranging from 10−2 to less than 1 Torr, and the high vacuum level may be a vacuum level ranging from 10−8 to less than 10−2 Torr.
As a preferred example, the low-vacuum pipe and the medium-high-vacuum pipe may be connected to the bottom of the vacuum chamber.
Specifically, at least one of the low-vacuum pipe and the medium-high-vacuum pipe may be disposed adjacent to a corner portion of the vacuum chamber up-down symmetrically, left-right symmetrically, or up-down-left-right symmetrically when the vacuum chamber is viewed from the top.
As one example, a low-vacuum gauge for measuring the low vacuum level and a medium-high-vacuum gauge for measuring the medium vacuum level or the high vacuum level may be installed in the vacuum chamber.
As a specific example, the low-vacuum evacuation device includes a low-vacuum evacuation pump connected to the vacuum chamber through the low-vacuum pipe and a low-vacuum switching valve configured to open and close the low-vacuum pipe.
As a more specific example, the low-vacuum evacuation pump may be configured by a rotary pump being connected or by a roots pump being connected to the rotary pump.
As a specific example, the low-vacuum switching valve may include an on/off valve installed in the low-vacuum pipe on the side of the low-vacuum evacuation pump and a multi-stage switching valve installed in the low-vacuum pipe on the side of the vacuum chamber and configured to regulate an opening degree.
As a more specific example, the multi-stage switching valve may be one of a servo valve, an SMC two-stage valve, and a throttle valve.
Specifically, the medium-high-vacuum evacuation device may include a medium-high-vacuum evacuation pump connected to the vacuum chamber through the medium-high-vacuum pipe and a medium-high-vacuum switching valve configured to open and close the medium-high-vacuum pipe.
As a specific example, the medium-high-vacuum evacuation pump may include a dry pump and a turbo molecular pump (TMP) connected to the dry pump by the medium-high-vacuum pipe and installed in the medium-high-vacuum pipe adjacent to the vacuum chamber.
As a more specific example, the medium-high-vacuum switching valve may include an on/off valve installed in the medium-high-vacuum pipe on the side of the dry pump and an adaptive pressure control (APC) valve installed in the medium-high-vacuum pipe between the TMP and the vacuum chamber and configured to regulate an opening degree.
As an example, the medium-high-vacuum pipe on the side of the dry pump may include a bypass pipe, a first and second on/off valves may be installed in the bypass pipe and the medium-high-vacuum pipe on the side of the dry pump respectively, and the first on/off valve and the second on/off valve may be sequentially opened.
As an example, the control unit may control the low-vacuum evacuation device and the medium-high-vacuum evacuation device to evacuate the vacuum chamber to a low vacuum level, a medium vacuum level, or a high vacuum level depending on a set process condition and to evacuate the vacuum chamber stepwise starting from the low vacuum level when the vacuum chamber is evacuated to the medium vacuum level or the high vacuum level.
As another example, while a predetermined number of electrode rolls are dried in the roll-to-roll state in the vacuum chamber and then removed from the vacuum chamber, the control unit may control the vacuum level stepwise to evacuate the vacuum chamber to a predetermined medium vacuum level or high vacuum level to remove foreign substances in the vacuum chamber.
As another aspect of the present invention, a method of vacuum-drying an electrode in a roll-to-roll state includes operations of evacuating a vacuum chamber to a low vacuum level according to a set process condition in order to vacuum-dry an electrode disposed in the roll-to-roll state in the vacuum chamber; and drying the electrode in the vacuum chamber at the low vacuum level, and further includes an operation of after drying a predetermined number of electrode rolls in the roll-to-roll state in the vacuum chamber, removing, in a state of the electrodes are removed from the vacuum chamber, foreign substances in the vacuum chamber setting to the vacuum chamber to a predetermined medium vacuum level or high vacuum level
Specifically, the predetermined medium vacuum level or high vacuum level may be obtained by evacuating the vacuum chamber to a low vacuum level and then stepwise starting from the low vacuum level until the predetermined medium vacuum level or high vacuum level is reached.
A method of vacuum-drying an electrode in a roll-to-roll state according to still another embodiment of the present invention includes operations of evacuating a vacuum chamber stepwise starting from a low vacuum level until a medium vacuum level or a high vacuum level is reached according to a set process condition to vacuum-dry an electrode disposed in the vacuum chamber in the roll-to-roll state and drying the electrode in the vacuum chamber at the medium vacuum level or the high vacuum level.
As one example, the method may further include an operation of, after drying a predetermined number of electrode rolls in the roll-to-roll state in the vacuum chamber, removing, in a state of the electrodes are removed from the vacuum chamber, foreign substances in the vacuum chamber setting to the vacuum chamber to a predetermined medium vacuum level or high vacuum level
According to the present invention, it is possible to efficiently remove moisture by applying various vacuum pressures while preventing vacuum damage to an electrode having a high moisture content.
Also, it is possible to further improve the wet performance of the electrode.
According to the present invention, it is possible to continuously vacuum-dry an electrode without preventing contamination by foreign substances in a vacuum chamber.
Hereinafter, the detailed configuration of the present invention will be described in detail with reference to the accompanying drawings and according to several embodiments. The following embodiments are illustratively shown in order to aid in understanding the present invention, the accompanying drawings are not drawn to scale to aid in understanding the present invention, and dimensions of some components may be exaggerated.
The present invention may be variously modified and have several forms, and specific embodiments will be shown in the accompanying drawings and described in detail below. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that the present invention encompasses any modifications, equivalents and substitutes included in the spirit and scope of the present invention.
An apparatus for vacuum-drying an electrode in a roll-to-roll state of the present invention includes a vacuum chamber in which an electrode is disposed in the roll-to-roll state and dried; a low-vacuum evacuation device connected to the vacuum chamber by a low-vacuum pipe and configured to evacuate the vacuum chamber to a low vacuum level; a medium-high-vacuum evacuation device connected to the vacuum chamber by a medium-high-vacuum pipe separate from the low-vacuum pipe and configured to evacuate the vacuum chamber to a medium vacuum level or a high vacuum level; and a control unit connected to the low-vacuum evacuation device and the medium-high-vacuum evacuation device and configured to regulate a vacuum level in the vacuum chamber stepwise to dry the electrode.
The conventional vacuum drying apparatus for vacuum-drying electrodes in a roll-to-roll heats and dries electrodes at a low vacuum level of 1 Torr or more and thus has a limitation in removing moisture from a high-moisture electrode such as electrodes coated with a high-nickel positive-electrode material or an electrode coated with an active material having a small particle size structure, which have recently been in the spotlight. Also, vacuum drying at a low vacuum level as described above had a limit on a bubble formation ability to improve wet performance
In order to solve this conventional problem, by including a low-vacuum evacuation device configured to evacuate a vacuum chamber to a low vacuum level and also a medium-high-vacuum evacuation device connected to a vacuum chamber by a pipe separate from the low-vacuum evacuation device, the present invention aims to remove moisture from a high-moisture electrode and improve wet performance. Also, by providing a control unit connected to the low-vacuum evacuation device and the medium-high-vacuum evacuation device and configured to regulate a vacuum level in the vacuum chamber stepwise to dry the electrode, the vacuum chamber can be rapidly evacuated to a medium vacuum degree or a high vacuum degree, and thus it is possible to prevent vacuum damage to the electrode in the chamber.
Meanwhile, the vacuum degree described herein may also be referred to as vacuum pressure (force) and will be expressed in units of Torr. The height of the vacuum level used during the vacuum drying of the electrode may be different from the height of the vacuum level classified in the general vacuum pumping field. In one embodiment, the low vacuum level is a vacuum level ranging from 1 to 600 Torr, that is, a vacuum level of 1 Torr or more. The low vacuum level is a vacuum pressure that can be applied not to a high-nickel positive electrode or an electrode having a small particle size structure but to an electrode of a conventional lithium secondary battery. Even if conventional electrodes other than the above-described high-moisture electrodes are vacuum-dried at the low vacuum level, it is possible to sufficiently remove moisture from the electrodes. However, for example, an electrode having a small particle size structure in which the nickel content of the positive electrode is increased or in which the particle size of the active material contained in the electrode is fine is vulnerable to external environments, and thus the electrode has a higher moisture content than the conventional electrode. In order to dry such an electrode with a higher moisture content and improve wet performance, it is preferable to evacuate the vacuum chamber to a higher vacuum level. To this end, in the present invention, a medium vacuum level of less than 1 Torr is applied, and also a high vacuum level of less than 10−2 Torr is applied if necessary. The preferred range of the medium vacuum level applied to the present invention may be from 10−2 to less than 1 Torr, and the range of the high vacuum level may be, for example, 10−8 to less than 10−2 Torr. If necessary, an ultra-high vacuum level of less than 10−8 Torr may be applied, but this may increase the electrode manufacturing cost. Therefore, it is desirable to select the vacuum level in consideration of available vacuum equipment and manufacturing cost. Also, as will be described later, according to an embodiment of the present invention, the vacuum chamber may be evacuated to a middle vacuum level or a high vacuum level in order to clean the vacuum chamber as well as perform vacuum drying. Thus, the range of the medium and high vacuum levels for the cleaning may be appropriately selected for efficiency within the vacuum level in the above range. However, the height of the medium vacuum level or the high vacuum level for the vacuum drying of electrodes does not necessarily match the height of the medium and high vacuum levels for chamber cleaning, and vacuum levels may be determined in ranges that can best achieve the respective purposes of the vacuum drying and cleaning.
Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and specific embodiments of the present disclosure.
The vacuum drying apparatus 100 of the present invention has a vacuum chamber 10 for drying an electrode in a roll-to-roll state. In
In order to vacuum-dry an electrode disposed in the vacuum chamber 10 in a roll-to-roll state, the vacuum drying apparatus 100 of the present invention includes a low-vacuum evacuation device connected to the vacuum chamber 10 through a low-vacuum pipe 21.
Also, according to the present invention, the vacuum drying apparatus 100 has a medium-high-vacuum evacuation device 30 connected to the vacuum chamber 10 through a medium-high-vacuum pipe 31 separate from the low-vacuum pipe 21.
According to the present invention, the two types of evacuation devices (the low-vacuum evacuation device and the medium-high evacuation device) are connected to the vacuum chamber 10 through separate vacuum pipes. Considering the simplification of the apparatus, it would be desirable to be able to perform evacuation from a low vacuum to a high vacuum using a single evacuating pump. However, for example, a turbo molecular pump (TMP) for performing evacuation to a high vacuum level has a structure suitable for high-speed rotation due to the structure of the pump device, and thus there is a risk of damage to a rotary shaft or pump parts when the pump rotates at a low speed to achieve a low vacuum level. Therefore, it is technically difficult to design a vacuum pump to perform evacuation from a low vacuum level even to a medium vacuum level, let alone a high vacuum level. Also, when the low-vacuum evacuation device 20 and the medium-high-vacuum evacuation device 30 are connected to a single pipe, it is difficult to regulate a vacuum level, and vacuum control is also very complicated. Also, when the regulation of the vacuum level fails, vacuum damage to the electrode in the vacuum chamber 10 may occur due to evacuation to the medium vacuum level or the high vacuum level.
Accordingly, according to the present invention, the low-vacuum evacuation device 20 and the medium-high-vacuum evacuation device 30 are connected to the vacuum chamber 10 through separate dedicated pipes. However, in the case of the medium-high-vacuum evacuation device 30, a device capable of performing evacuation over the range of the medium vacuum level to the high vacuum level, which is defined in the present invention, may be employed. It will be appreciated that the medium-high-vacuum evacuation device 30 is separated into the medium-vacuum evacuation device and the high-vacuum evacuation device, which are connected respectively to the vacuum chamber through separate pipes. However, in this case, the configuration of the vacuum drying apparatus 100 is too complicated, resulting in an increase in manufacturing cost and an increase in the complexity of the vacuum control flow. Also, when the vacuum level is increased stepwise from the medium vacuum level to the high vacuum level by the medium-high evacuation device 30, it is possible to more effectively prevent vacuum damage to an electrode.
Referring to
The plan view of
In
As the low-vacuum gauge A, for example, a capacitance manometer (CA) gauge that converts pressure change motion of a thin diaphragm into an electric signal proportional to the pressure may be employed. The CA gauge may measure a wide area ranging from 1 to 1,000 Torr and generates a signal by a physical change in the gauge rather than a change in gas properties in the chamber. Thus, the CA gauge can measure values independent of the gas composition in the measurement chamber and has the advantage of having relatively high accuracy.
Examples of the medium-high-vacuum gauge B may include ion gauges that ionize gas and amplify and measure ion currents. Among the ion gauges, a Bayard-Alpert (BA) ion gage, which is suitable for measuring a lower vacuum level by reducing X-rays generated from the ion gauge, is preferable.
For convenience of description, it is shown in
The low-vacuum evacuation device 20 connected to the vacuum chamber 10 of the vacuum drying apparatus 100 of the present invention by the low-vacuum pipe 21 includes a low-vacuum evacuation pump connected to the vacuum chamber 10 through the low-vacuum pipe 21 and a low-vacuum switching valve configured to open and close the low-vacuum pipe 21.
As an example of the low-vacuum evacuation pump 22, a rotary pump that suctions, compresses, and discharges gas by the rotation of a vane may be used. As another example, a roots pump connected in series to the rotary pump as an auxiliary pump may be used. The roots pump is a pump that discharges gas entering an intake port using two rotors rotating in opposite directions. Connecting the roots pump to the rotary pump can increase the discharging speed and prevent contamination due to the backflow of lubricant oil in the rotary pump. The above rotary pump or roots pump is used in a rough vacuum region in the range of 760 to 1 Torr. The rotary pump and the roots pump are pumps commonly used in the field of vacuum technology, and thus a detailed description thereof will be omitted.
As shown in
As described above, in this embodiment, by installing the multi-stage switching valve 24 in the low-vacuum pipe 21 on the side of the vacuum chamber 10, the vacuum chamber 10 may be evacuated stepwise until a desired low vacuum level is reached. In addition, for example, by regulating the opening degree of the servo valve, a specific low vacuum level may be maintained, or the corresponding vacuum level may be changed to another vacuum level.
In order to return the vacuum chamber 10 to atmospheric pressure after the vacuum chamber 10 is evacuated to a predetermined low vacuum level to dry the electrode, a vent pipe 25 and a vent valve 26 are installed in the low-vacuum pipe 21. The vent valve 26 may be closed when the on/off valve 23 is opened and may be opened to restore the pressure in the vacuum chamber 10 when the on/off valve 23 is closed.
The vacuum drying apparatus 100 of the present invention includes a medium-high-vacuum evacuation device 30 connected to the vacuum chamber 10 through the medium-high-vacuum pipe 31 separate from the low-vacuum pipe 21. Specifically, the medium-high-vacuum evacuation device 30 includes a medium-high-vacuum evacuation pump connected to the vacuum chamber 10 through the medium-high-vacuum pipe 31 and a medium-high-vacuum switching valve configured to open and close the medium-high-vaccum pipe.
In the embodiment of
The TMP 37 is a turbo molecular pump and is a pump that can achieve vacuum levels of 10−3 Torr, which is a medium vacuum level, and 10−10 Torr, which is an ultra-high vacuum level, through an alternating arrangement of a rotary shaft that rotates at a high rate and a fixed shaft inclined in the opposite direction of the rotary shaft.
In the embodiment of
Therefore, the medium-high-vacuum evacuation device 30 according to this embodiment may evacuate the vacuum chamber 10 stepwise until a desired vacuum level is reached by installing the APC valve 34 in the medium-high-vacuum pipe 31 on the side of the vacuum chamber and may maintain a specific low vacuum level or high vacuum level or change the corresponding vacuum level to another vacuum level, for example, by regulating the opening degree of the APC valve 34.
In order for the medium-high-vacuum evacuation device 30 to increase pressure in the vacuum chamber 10 after evacuating the vacuum chamber 10 to a predetermined medium vacuum level or high vacuum level to dry an electrode, the vent pipe 35 and the vent valve 36 are installed in the medium-high-vacuum pipe. The vent valve 36 may be closed when the on/off valve 33 is opened and may be opened to restore the pressure in the vacuum chamber 10 when the on/off valve 33 is closed.
In an embodiment of
As described above, according to the present invention, the low-vacuum evacuation device 20 and the medium-high-vacuum evacuation device 30 connected to the vacuum chamber 10 by separate vacuum pipes are provided, and the evacuation devices are connected to a control unit 40. By controlling the low-vacuum evacuation device and the medium-high-vacuum evacuation device such that the vacuum level in the vacuum chamber 10 is regulated stepwise to dry the electrode, the control unit 40 performs control to evacuate the vacuum chamber 10 to a low vacuum level, a medium vacuum level, or a high vacuum level according to set process conditions without applying vacuum damage to the electrode. In particular, when evacuating the vacuum chamber 10 to a medium vacuum level or a high vacuum level, the control unit 40 of the present invention controls the low-vacuum evacuation device and the medium-high-vacuum evacuation device to evacuate the vacuum chamber 10 from the low vacuum level to the medium vacuum level or the high vacuum level stepwise rather than to the medium vacuum level or the high vacuum level immediately.
Also, according to the present invention, since the medium-high-vacuum evacuation device 30 is provided in addition to the low-vacuum evacuation device 20, it is possible to remove foreign substances in the vacuum chamber 10 using the medium-high-vacuum evacuation device 30. While the process of introducing an electrode roll into the vacuum chamber 10 and vacuum-drying the electrode is repeated in a roll-to-roll state, foreign substances derived from the electrode are generated in the vacuum chamber 10. A typical low vacuum level used for vacuum-drying electrodes has a limit to removing foreign substances. While a predetermined number of electrode rolls are dried in the vacuum chamber 10 in a roll-to-roll state and then the electrode is removed from the vacuum chamber 10, the control unit 40 of the present invention may control the vacuum level stepwise to evacuate the vacuum chamber 10 to a predetermined medium vacuum level or high vacuum level to remove foreign substances in the vacuum chamber 10.
After the notching process, the electrode 1 is wound on a core, and an electrode roll 1a in which the electrode is wound on the core is installed in a loader 2a outside the vacuum chamber 10. The electrode roll 1a is installed in an unwinder 2b in the chamber by a robot that is not shown. Subsequently, an electrode roll 1b is unwound from the unwinder 2b, and the electrode 1 is connected to a rewinder 2c installed in the vacuum chamber 10. When such an electrode is disposed between the unwinder 2b and the rewinder 2c in a roll-to-roll state, the vacuum chamber 10 is evacuated to dry the electrode. The electrode 1 proceeds in the vacuum chamber 10 in a roll-to-roll state when the unwinder 2b and the rewinder 2c are driven, and the electrode 1 in a roll-to-roll state proceeds to the rewinder 2c while the tension is regulated and the meandering is prevented by a meandering adjustment unit 3 and a tension adjustment unit 4 installed in the vacuum chamber 10. While the vacuum chamber 10 is evacuated in a roll-to-roll state by the vacuum drying apparatus 100 shown in
The operations and the vacuum drying method of the vacuum drying apparatus 100 of the present invention will be described in detail below with reference to
The vacuum drying method of an electrode in a roll-to-roll state according to an embodiment of the present invention includes operations of evacuating a vacuum chamber to a low vacuum level according to a set process condition in order to vacuum-dry an electrode in a roll-to-roll state in the vacuum chamber (operation (a) of
In operation (a), while the electrode rolls 1b and 1c are disposed between the unwinder 2b and the rewinder 2c in the vacuum chamber 10 as shown in
In operation (b), when the low vacuum level corresponding to the process condition is stabilized and maintained in the vacuum chamber 10, the control unit 40 may operate the heating unit 5 of
In operation (c), the dried electrode is wound by the rewinder 2c, and then the wound electrode roll 1c is discharged to the outside of the vacuum chamber 10. Before the electrode is discharged to the outside of the chamber, the low vacuum switching valve (on/off valve and servo valve) of the low-vacuum evacuation device 20 is closed, and the vent valve 26 is opened to bring the internal pressure of the vacuum chamber 10 to atmospheric pressure. An electrode roll 1d discharged to the outside of the chamber is mounted on the unloader 2d. Subsequently, the electrode is vacuum-dried in a roll-to-roll state in the vacuum chamber 10 by repeating operations (a) to (c).
In operation (d), the vacuum drying method according to an embodiment of the present invention further includes a cleaning process for removing foreign substances in the vacuum chamber 10. When a predetermined number of electrode rolls are vacuum-dried in a roll-to-roll state in the vacuum chamber 10 by repeating operations (a) and (b) or operations (a) to (c), foreign substances derived from the electrode or introduced from the outside may accumulate in the vacuum chamber. When the subsequent electrode roll is vacuum-dried in the vacuum chamber 10 in the presence of such foreign substances, the electrode may be contaminated with the foreign substances, and the electrode characteristics or the wet performance may be degraded. Accordingly, the vacuum drying method of the present invention further includes an operation of after vacuum-drying a predetermined number of, for example, 50, electrode rolls in the vacuum chamber 10, removing, in a state of the electrodes are removed from the vacuum chamber, foreign substances in the vacuum chamber 10 setting to the vacuum chamber 10 to a predetermined medium vacuum level or high vacuum level
In this case, the predetermined medium vacuum level or high vacuum level is obtained by evacuating the vacuum chamber 10 to a low vacuum level and then stepwise until the predetermined medium vacuum level or high vacuum level is reached starting from the low vacuum level. As described above, when the vacuum chamber 10 is evacuated immediately to the medium or high vacuum level, there is a possibility that the rotary shaft or parts of the TMP 37 of the medium-high-vacuum evacuation device 30 may be damaged. Therefore, it is necessary to make the inside of the vacuum chamber 10 into a low vacuum level atmosphere first before setting the inside of the vacuum chamber 10 to a predetermined medium-high-vacuum level. Specifically, when there is no electrode in the vacuum chamber 10 and the vacuum chamber 10 is returned to atmospheric pressure, the vacuum chamber 10 is evacuated to the low-vacuum level by opening the on/off valve 23 and the servo valve 24 while the low-vacuum evacuation pump 22 (e.g., a rotary pump) of
Also, whether a target vacuum level (a low vacuum level and a medium-high vacuum level) is achieved in the vacuum chamber may be checked by measuring the low vacuum level using the low-vacuum gauge (A) shown in
The vacuum drying method of this embodiment includes operations of evacuating a vacuum chamber stepwise until the medium vacuum level or the high vacuum level is reached starting from the low vacuum level according to a set process condition to vacuum-dry an electrode disposed in the vacuum chamber in a roll-to-roll state; and drying the electrode in the vacuum chamber at the medium vacuum level or the high vacuum level.
This embodiment is suitable for application to electrodes having a high moisture content or needing improvement of wet performance and relates to a method of evacuating a vacuum chamber stepwise to a medium vacuum level or a high vacuum level to carry out drying.
In operation (a), while the electrode roll is disposed between the unwinder 2b and the rewinder 2c in the vacuum chamber 10 as shown in
In operation (a-1), in this embodiment, by activating the medium-high-vacuum evacuation device 30 of
In operation (b)′, at the medium vacuum level or high vacuum level corresponding to the process condition, the control unit 40 operates the heating unit 5 of
In operation (c), the dried electrode is wound by the rewinder 2c and discharged to the outside of the vacuum chamber 10. Before the electrode is discharged to the outside of the chamber 10, the medium-high-vacuum switching valve (on/off valve and servo valve) of the medium-high-vacuum evacuation device 30 is closed, and the vent valve 36 is opened (primary vent). Also, in this state, the vent valve 26 of the low-vacuum evacuation device is opened so that the vacuum chamber 10 can quickly return to atmospheric pressure (secondary vent). Subsequently, the electrode is vacuum-dried in a roll-to-roll state in the vacuum chamber 10 by repeating operations (a) to (c).
In operation (d), the vacuum drying method according to an embodiment of the present invention may further include a cleaning process for removing foreign substances in the vacuum chamber 10. When a predetermined number of electrode rolls are vacuum-dried in a roll-to-roll state in the vacuum chamber by repeating operations (a) and (b)′ or operations (a) to (c), foreign substances derived from the electrode or introduced from the outside may be accumulated in the vacuum chamber. The vacuum drying method of the present invention further includes an operation of after vacuum-drying a predetermined number of, for example, 50, electrode rolls in the vacuum chamber 10, removing, in a state of the electrodes are removed from the vacuum chamber, foreign substances in the vacuum chamber 10 setting to the vacuum chamber 10 to a predetermined medium vacuum level or high vacuum level.
The predetermined medium vacuum level or high vacuum level for removing foreign substances in the chamber does not necessarily coincide with a medium vacuum level or high vacuum level for drying an electrode having a high moisture content. Since the purposes of electrode drying and foreign substance removal are different, a medium vacuum level or a high vacuum level may be selected in an optimal range suitable for each purpose. Since the vacuum drying apparatus 100 of the present invention employs the APC valve 34 capable of regulating the opening degree, a desired medium vacuum level or high vacuum level can be achieved by adjusting the opening degree. A process of performing evacuation stepwise starting from a low vacuum level until the predetermined medium vacuum level or high vacuum level for removing foreign substances is reached is the same as that of the embodiment of
Based on the above description, the vacuum drying apparatus of the present invention is used for various vacuum levels ranging from tens to hundreds of Torr to 10−8 Torr by providing a low-vacuum evacuation device and a medium-high-vacuum evacuation device. Therefore, the vacuum drying apparatus can be used to dry a model of electrode having a low moisture content as well as a high-nickel electrode having a high moisture content.
Also, through application to various vacuum pressures (vacuum levels) as described above, it is possible to improve not only the electrode moisture removal ability but also the wet performance
In addition, even in each vacuum mode of low vacuum or medium vacuum, the vacuum level can be finely regulated stepwise by employing a servo valve or an APC valve, and thus it is possible to stabilize or regulate the vacuum level very conveniently.
In addition, since both a low-vacuum evacuation device and a medium-high-vacuum evacuation device are provided, it is advantageously possible to remove foreign substances in a vacuum chamber by the medium-high-vacuum evacuation device without vacuum damage.
Meanwhile, with the above-described advantages, the vacuum drying method of the present invention can also effectively vacuum-dry electrodes in a vacuum chamber in a roll-to-roll state.
So far, the present invention has been described in detail with reference to the accompanying drawings, the embodiments, and the like. However, the configurations described in the drawings or embodiments described herein are only examples of the present invention and do not represent all the technical spirit of the present invention, and it should be understood that various equivalents and modifications may be substituted for the configurations at the time of filing the present application.
1: Electrode
1
a, 1b, 1c, 1d: Electrode roll
2
a: Loader
2
b: Unwinder
2
c: Rewinder
2
d: Unloader
3: Meandering adjustment unit
4: Tension adjustment unit
5: Heating unit
6: Nitrogen gas spray unit
7: Fan
10: Vacuum chamber
A: Low-vacuum gauge
B: Medium-high-vacuum gauge
20: Low-vacuum evacuation device
21: Low-vacuum pipe
22: Low-vacuum evacuation pump
23: On/off valve
24: Multi-stage switching valve
25: Vent pipe
26: Vent valve
30: Medium-high-vacuum evacuation device
31: Medium-high-vacuum pipe
31-1: Bypass pipe
32: Dry pump
33S: First on/off valve
33F: Second on/off valve
34: APC valve
35: Vent pipe
36: Vent valve
37: TMP
40: Control unit
100: Vacuum drying apparatus
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0027817 | Mar 2021 | KR | national |
The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2022/002741 filed on Feb. 24, 2022, which claims the priority from Korean Patent Application No. 10-2021-0027817, filed on Mar. 3, 2021, the disclosures of which are incorporated herein by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/002741 | 2/24/2022 | WO |
