Rolling device for manufacturing secondary battery

Abstract

Disclosed herein is a rolling apparatus for performing hot rolling on an electrode coated with an electrode active material, in which, in one example, a preheater is disposed upstream of a rolling unit that performs rolling on an electrode conveyed in a roll-to-roll manner, and the preheater irradiates an infrared laser in a width direction of a surface of the electrode, the surface of the electrode is heated in the form of radiant heat.

Description

Technical Field

[0001] This disclosure relates to a rolling device for performing hot rolling of electrodes on secondary batteries.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0173935, filed on December 5, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0003] With the development of technology and the increasing demand for mobile devices, the demand for rechargeable batteries as an energy source is also growing rapidly. Therefore, people are conducting extensive research on rechargeable batteries that can meet various needs.

[0004] In terms of battery shape, square and pouch-shaped rechargeable batteries are in high demand because of their thinness and can be used in products such as mobile phones. In terms of materials, lithium rechargeable batteries such as lithium-ion batteries and lithium-ion polymer batteries are in high demand because they have advantages such as high energy density, high discharge voltage and high output stability.

[0005] This type of secondary battery is manufactured through the following steps: coating an electrode mixture containing active materials, conductive materials and binders onto an electrode sheet, then producing electrodes through rolling, drying, slitting and notching processes; stacking the electrodes and separator alternately to form an electrode assembly; then installing the electrode assembly into a battery casing, injecting electrolyte and sealing it.

[0006] Many of the processes performed during the manufacture of this type of secondary battery are carried out in a roll-to-roll manner. In other words, processes such as rolling and drying are performed by unwinding the electrode roll using an unwinding machine while simultaneously winding the processed electrode roll up using a rewinding machine on the other side.

[0007] In the rolling process, a rolling device is used to apply pressure by moving electrodes between two rolls. Hot rolling using the rolling device raises the temperature of the electrodes to reduce surface hardness, thereby achieving high rolling density with a smaller reduction force. Current electrode heating methods use electric heating rods to directly heat the rolls, which then conduct heat to the electrode surface.

[0008] However, conductive heating has a slow heating response. Even after the power to the heating rod is cut off, residual heat remains, resulting in slow cooling. Furthermore, because heat conduction to the electrodes takes time, it is difficult to increase the moving speed of the electrode rollers. Although increasing the roller speed can shorten the production cycle time, conductive heating still has limitations in terms of process improvement.

[0009] Technical issues

[0010] The purpose of this disclosure is to provide a rolling device that utilizes radiant heat to improve the heating and cooling responsiveness of the electrode surface and selectively heats the electrode active material, thereby avoiding quality problems such as wrinkles in uncoated areas caused by foil expansion.

[0011] However, the technical problems to be solved by this disclosure are not limited to those described above, and those skilled in the art will clearly understand other problems not mentioned from the description of this disclosure below. Summary of the Invention

[0012] This disclosure relates to a rolling apparatus for performing hot rolling on an electrode coated with an electrode active material, wherein, in one example, a preheater is disposed upstream of a rolling unit for performing rolling on an electrode conveyed in a roll-to-roll manner, and the preheater irradiates an infrared laser along the width direction of the electrode surface to heat the electrode surface in the form of radiative heat.

[0013] In one embodiment of this disclosure, the wavelength of the infrared laser irradiated by the preheater has an absorption rate of at least 10% or less for copper or aluminum, which are used as electrode materials, and at least 70% or more for the electrode active material.

[0014] For example, the wavelength of infrared lasers can be in the range of 1064±100nm.

[0015] In addition, the output of the infrared laser can be controlled to maintain the temperature of the electrode active material within the range of 80±5℃.

[0016] In one embodiment, the output of the infrared laser can be controlled per unit time according to the change in the transmission speed of the electrodes.

[0017] In addition, the preheater irradiates infrared laser light across the transport direction of the coil-to-coil electrodes in the form of a line beam or a square beam.

[0018] Meanwhile, this disclosure provides a hot rolling method for electrodes for secondary batteries, wherein electrodes coated with electrode active materials are conveyed in a roll-to-roll manner, and a preheater disposed upstream of the rolling unit that performs rolling on the electrodes is irradiated with infrared laser along the width direction of the electrode surface to heat the electrode surface in the form of radiative heat.

[0019] Preferably, the wavelength of the infrared laser irradiated by the preheater can be in the range of having an absorption rate of 10% or less for copper or aluminum as electrode materials, while having an absorption rate of 70% or higher for electrode active materials.

[0020] For example, the wavelength of infrared lasers can be in the range of 1064±100nm.

[0021] In addition, the output of the infrared laser can be controlled according to the change in the transmission speed of the electrode per unit time, thereby maintaining the temperature of the electrode active material within the range of 80±5℃.

[0022] Beneficial effects

[0023] According to the rolling apparatus of this disclosure with the above configuration, the electrode surface is heated by an infrared laser irradiated by a preheater. In other words, the electrode is heated by radiative heat transfer rather than conductive heat transfer.

[0024] Therefore, the roller pressing device according to this disclosure has a fast heating response speed due to radiant heat. When the power is cut off, the preheater cools down immediately without residual heat, and the travel speed of the electrode roller is more easily increased due to the rapid heat transfer.

[0025] In addition, since radiant heat selectively heats the electrode active material rather than the metal material, problems such as wrinkles caused by the expansion of uncoated portions without electrode active material do not occur.

[0026] However, the technical effects that can be obtained through this disclosure are not limited to those described above, and those skilled in the art can clearly understand other effects not mentioned from the description of the disclosure below. Attached Figure Description

[0027] Since the accompanying drawings illustrate exemplary embodiments of this disclosure and, together with the detailed description of this disclosure below, are used to help understand the technical ideas of this disclosure, this disclosure should not be interpreted restrictively based solely on the drawings.

[0028] Figure 1 This is a schematic diagram illustrating a roller pressing apparatus according to an embodiment of the present disclosure.

[0029] Figure 2 This is a graph showing the absorption rates of copper and aluminum for infrared wavelengths.

[0030] Figure 3 This is a schematic diagram showing the infrared absorption mode in an electrode coated with an electrode active material.

[0031] Figure 4 This diagram shows an infrared laser being irradiated onto an electrode surface coated with an electrode active material.

[0032] Figure 5 This is a flowchart of a hot rolling method for electrodes used in secondary batteries. Detailed Implementation

[0033] This disclosure can be modified and implemented in various ways, and therefore specific embodiments will be described in detail below.

[0034] However, it should be understood that this disclosure is not limited to the specific embodiments, but includes all modifications, equivalents or alternatives within the spirit and technical scope of this disclosure.

[0035] The terms “comprising,” “including,” and “having” as used herein indicate the presence of the features, figures, steps, actions, components, or elements or combinations thereof described in the specification, and it should be understood that the possibility of the presence or addition of one or more other features, figures, steps, actions, components, elements, or combinations thereof is not excluded in advance.

[0036] Furthermore, in this disclosure, when a portion of a layer, film, region, plate, etc., is disposed "above" another portion, this includes not only the case where one portion is disposed "directly above" another portion, but also the case where the other portion is situated between them. Conversely, when a portion of a layer, film, region, plate, etc., is disposed "below" another portion, this includes not only the case where one portion is disposed "directly below" another portion, but also the case where the other portion is situated between them. Moreover, in this application, "above" includes not only the case where it is disposed at the top, but also the case where it is disposed at the bottom.

[0037] This disclosure relates to a rolling apparatus for performing hot rolling on an electrode coated with an electrode active material, wherein, in one example, a preheater is disposed upstream of a rolling unit for rolling electrodes conveyed in a roll-to-roll manner, and the preheater irradiates an infrared laser along the width direction of the electrode surface to heat the electrode surface in the form of radiative heat.

[0038] According to the rolling apparatus of this disclosure with the above configuration, the electrode surface is heated by an infrared laser irradiated by a preheater. In other words, the electrode is heated by radiative heat transfer rather than conductive heat transfer.

[0039] Therefore, the roller pressing device according to this disclosure has a fast heating response speed due to radiant heat. When the power is cut off, the preheater cools down immediately without residual heat, and the travel speed of the electrode roller is more easily increased through rapid heat transfer.

[0040] Detailed Implementation Examples

[0041] A specific embodiment of the roller pressing device 10 according to the present disclosure will now be described in detail with reference to the accompanying drawings. For reference, the directions used in the following description to indicate relative positions (front, back, up, down, left, right) are for understanding the present disclosure, and unless otherwise stated, refer to the directions shown in the accompanying drawings.

[0042] First Embodiment

[0043] Figure 1 This is a schematic diagram illustrating a roller pressing apparatus 10 according to an embodiment of the present disclosure.

[0044] The rolling device 10 refers to a device that applies pressure to the surface of the electrode 300 coated with the electrode active material 310 to perform a rolling process, thereby increasing the density of the active material 310 and making its thickness uniform. For the roll-to-roll rolling process, the electrode 300 coated with the electrode active material 310 is wound onto a spool, and the spool with the electrode 300 wound is mounted on an unwinding machine 100. The electrode 300 mounted on the unwinding machine 100 is unwound, and at the downstream rewinding machine 140, the unwound electrode 300 is wound back to its original winding form. The electrode 300 transported in a roll-to-roll manner is subjected to appropriate tension to prevent problems such as sagging or undulation of the electrode 300.

[0045] A pressing unit 120 is provided between the unwinder 100 and the rewinder 140. The pressing unit 120 applies a set pressure as the electrode 300 passes between a pair of rotating rollers. The pressure increases the density of the active material 310 of the electrode 300, while simultaneously achieving uniform thickness. Additionally, the pressing device 10 includes a feeding mechanism 110 and a discharging mechanism 130. The feeding mechanism 110 is located between the unwinder 100 and the pressing unit 120, and the discharging mechanism 130 is located between the pressing unit 120 and the rewinder 140. The feeding mechanism 110 and the discharging mechanism 130 adjust the tension applied to the electrode 300 or align the electrode 300 to ensure smooth transport of the electrode 300. For example, the swaying phenomenon when the electrode 300 travels at an angle can be corrected by the feeding mechanism 110 and the discharging mechanism 130.

[0046] The rolling apparatus 10 of this disclosure includes a preheater 200 for performing hot rolling. Hot rolling increases the temperature of the electrode 300 and reduces its surface hardness, thereby achieving a higher rolling density with a smaller rolling force. Therefore, the preheater 200 is positioned upstream of a rolling unit 120 that performs rolling on the electrode 300, which is conveyed in a roll-to-roll manner. Rolling is performed at the rolling unit 120 when the electrode 300 is properly heated by the preheater 200.

[0047] In the rolling apparatus 10 of this disclosure, the preheater 200 irradiates an infrared laser along the width direction of the surface of the conveyed electrode 300, heating the surface of the electrode 300 in the form of radiative heat. The heating of the electrode 300 by the infrared radiation is selectively absorbed by the metallic electrode 300 and the electrode active material 310 coated on its surface. In other words, there is a significant difference in the absorption rate of infrared radiation between the electrode 300 and the electrode active material 310.

[0048] Figure 2 This is a graph showing the absorption rates of copper and aluminum for infrared wavelengths. Copper and aluminum are representative materials for electrode 300 (positive and negative electrodes), such as... Figure 2 As shown, copper or aluminum has an absorption rate of at least 10% or less for infrared light. In contrast, the near-black electrode active material 310 has an absorption rate of at least 70% or more for infrared light. Therefore, when irradiated with an infrared laser of the same output along the width of the electrode 300 surface, the temperature rise of the electrode active material 310 is significantly greater than that of the electrode 300 due to the significant difference in absorption rate.

[0049] For example, the wavelength of infrared lasers can be in the range of 1064 ± 100 nm. Within this wavelength range, the absorptivity of copper is less than about 1%, and that of aluminum is less than about 5%. In contrast, the absorptivity of electrode active material 310 reaches about 80% or higher. That is, at a reference wavelength of 1064 nm, electrode active material 310 absorbs most of the infrared radiation, while copper and aluminum reflect almost all of the infrared radiation.

[0050] Figure 3 This is a schematic diagram of the infrared absorption mode in the electrode 300 coated with electrode active material 310. Electrode active material 310 is coated on the surface of electrode 300, and a laser irradiator 210 equipped in the preheater 200 emits infrared laser light. The infrared laser first irradiates the surface of electrode active material 310; some infrared light is reflected from the surface of electrode active material 310, but most of the infrared energy is absorbed by electrode active material 310. Furthermore, some infrared radiation reaches the surface of electrode 300, but most of the infrared radiation is reflected from the surface of electrode 300 and reabsorbed by electrode active material 310.

[0051] When the electrode 300 is heated by radiative heat from an infrared laser in this manner, most of the energy is absorbed by the electrode active material 310, and only a very small amount of energy is absorbed by the copper or aluminum electrode 300. Radiative heating has a fast response speed; energy transfer is immediately cut off when infrared radiation stops, and the selective heating by infrared radiation does not significantly increase the temperature of the electrode 300. Therefore, since the temperature rise of the electrode 300 without the electrode active material 310 coating is significantly lower than that under conventional conductive heating, problems such as wrinkles in the uncoated portion 320 caused by electrode 300 expansion are also solved.

[0052] Figure 4 This is a diagram illustrating an example of irradiating an infrared laser onto the surface of an electrode 300 coated with electrode active material 310. Figure 4In the exemplary embodiment shown, the preheater 200 is equipped with two laser irradiators 210. Each laser irradiator 210 emits infrared light in the wavelength range of 1,064 ± 100 nm and can irradiate the infrared laser across the delivery direction of the roll-to-roll electrodes in a line beam or square beam manner.

[0053] Furthermore, the operation of the laser irradiator 210 is controlled by the preheater controller 220. The preheater controller 220 can also adjust the laser output. By controlling the output of the infrared laser, the heating temperature can be adjusted to increase the temperature of the electrode 300. For example, the output of the infrared laser can be controlled to maintain the temperature of the electrode active material 310 within the range of 80±5°C.

[0054] For feedback control, a temperature sensor 230 for measuring the temperature of the electrode active material 310 can be placed downstream of the preheater 200. The temperature sensor 230 can measure the temperature of the electrode active material 310, for example, in a non-contact manner. Based on the measured temperature of the electrode active material 310, the output of the infrared laser can be variably adjusted.

[0055] Furthermore, since the preheater 200 heats the conveyed electrode 300 in a roll-to-roll manner, the output of the infrared laser preferably varies according to the conveying speed of the electrode 300. In other words, since the time for radiative heat transfer varies depending on the conveying speed, the conveying speed of the electrode 300 must be considered simultaneously when controlling the laser output. Therefore, the output of the infrared laser can be controlled according to the output per unit time that varies according to the conveying speed of the electrode 300.

[0056] Therefore, as the conveying speed of electrode 300 increases, the infrared laser irradiates with a higher output per unit time, thereby raising the temperature of the electrode active material 310 to the desired level, for example, within the range of 80 ± 5°C. This is achieved through the high responsiveness of radiative heat and the instantaneous output control of the laser irradiator 210; in other words, this means that the roll-to-roll conveying speed can be increased within the allowable range of infrared laser output per unit time. Therefore, the roll pressing device 10 of this disclosure is advantageous for shortening the production cycle time by increasing the movement speed of the rolls.

[0057] Second Embodiment

[0058] Meanwhile, this disclosure provides an electrode rolling method for secondary batteries, wherein electrodes 300 coated with electrode active material 310 are conveyed in a roll-to-roll manner, and a preheater 200 disposed upstream of a rolling unit 120 for rolling the electrodes 300 is irradiated with infrared laser along the width direction of the electrode surface to heat the electrode surface 300 in the form of radiative heat. The main configuration of this electrode hot rolling method for secondary batteries is summarized in... Figure 5 In the flowchart.

[0059] As described in the first embodiment, the wavelength of the infrared laser irradiated by the preheater 200 is preferably within the range that the absorption rate is at least 10% or lower for the copper or aluminum material of the electrode 300, and at least 70% or higher for the electrode active material 310.

[0060] For example, the wavelength of the infrared laser irradiated by the preheater 200 can be in the range of 1064±100nm.

[0061] Furthermore, the output of the infrared laser can be controlled to be output per unit time according to the change in the transmission speed of the electrode 300, so that the temperature of the electrode active material 310 is maintained within the range of 80±5°C. As described above, a temperature sensor 230 for measuring the temperature of the electrode active material 310 can be provided downstream of the preheater 200 for feedback control.

[0062] As described above, this disclosure has been described in more detail with reference to the accompanying drawings, embodiments, etc. However, since the configurations described in the accompanying drawings or embodiments are only one embodiment of this disclosure and do not represent the overall technical spirit of this disclosure, it should be understood that this disclosure covers various equivalents, modifications, and substitutions at the time of filing this application.

[0063] Explanation of reference numerals in the attached figures

[0064] 10: Roller pressing device

[0065] 100: Unwinding machine

[0066] 110: Feeding mechanism

[0067] 120: Roller pressing unit

[0068] 130: Discharge mechanism

[0069] 140: Winding machine

[0070] 200: Preheater

[0071] 210: Laser Illuminator

[0072] 220: Preheater Controller

[0073] 230: Temperature sensor

[0074] 300: Electrode

[0075] 310: Electrode active materials

[0076] 320: Uncoated area

Claims

1. A rolling apparatus for performing hot rolling on an electrode coated with an electrode active material, wherein, The preheater is located upstream of the rolling unit that performs rolling on the electrodes conveyed in a roll-to-roll manner, and The preheater irradiates an infrared laser along the width of the electrode surface to heat the electrode surface in the form of radiative heat.

2. The roller pressing device according to claim 1, wherein, The wavelength of the infrared laser irradiated by the preheater has an absorption rate of 10% or less for copper or aluminum, which are the materials used as electrodes, and an absorption rate of 70% or more for the active material of the electrode.

3. The roller pressing device according to claim 2, wherein, The wavelength of the infrared laser is in the range of 1064±100nm.

4. The roller pressing device according to claim 3, wherein, The output of the infrared laser is controlled to maintain the temperature of the electrode active material within the range of 80±5℃.

5. The roller pressing device according to claim 4, wherein, The output of the infrared laser is controlled according to the change in the transmission speed of the electrode per unit time.

6. The roller pressing device according to claim 1, wherein, The preheater irradiates the infrared laser across the transport direction of the electrodes, which are transported in a roll-to-roll manner, in the form of a line beam or a square beam.

7. A hot rolling method for electrodes used in secondary batteries, wherein, Electrodes coated with electrode active material are transported in a roll-to-roll manner. In this process, a preheater located upstream of the rolling unit that performs rolling on the electrode is irradiated with infrared laser along the width direction of the electrode surface to heat the electrode surface in the form of radiative heat.

8. The hot rolling method for electrodes of a secondary battery according to claim 7, wherein, The wavelength range of the infrared laser irradiated by the preheater has an absorption rate of 10% or less for copper or aluminum, which are used as electrode materials, and an absorption rate of 70% or more for the electrode active material.

9. The hot rolling method for electrodes of a secondary battery according to claim 8, wherein, The wavelength of the infrared laser is in the range of 1064±100nm.

10. The hot rolling method for electrodes of a secondary battery according to claim 9, wherein, The output of the infrared laser is controlled according to the change in the transmission speed of the electrode per unit time, thereby maintaining the temperature of the electrode active material within the range of 80±5℃.

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