Electrode material rolling unit for secondary battery

Abstract

An electrode material rolling unit for a secondary battery according to the present invention configured as described above can quickly and stably transfer an electrode material, and in particular, can continuously supply an electrode material having a uniform thickness without thickness variations due to the good spreadability of the electrode material in the width direction.

Description

Rolling unit for electrode materials for secondary batteries

[0001] The present invention relates to a coating device for coating an electrode material on a current collector, and more specifically, to an electrode material rolling unit for a secondary battery that enables stable transport of the electrode material and allows for the continuous supply of an electrode material of uniform thickness without thickness variation by ensuring good spreadability of the electrode material in the width direction.

[0002] Unlike primary batteries, which are used once and then discarded, secondary batteries are rechargeable batteries that can be reused repeatedly and possess high output and excellent charge / discharge performance. Accordingly, they are being used importantly in various fields, ranging from mobile IT devices such as smartphones and laptop computers to power sources for electric vehicles and storage devices for storing electricity generated from wind or solar power.

[0003] A secondary battery has a basic composition of a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode and the negative electrode are each manufactured into a secondary battery cell through an electrode process in which an active material, a conductive material, and a binder are dispersed or dissolved in a solvent to prepare a slurry, and the slurry is coated onto a current collector and then dried, followed by an assembly process and an activation process.

[0004] However, wet electrode manufacturing methods using solvents may result in defects such as pinholes or cracks during the drying process. Pinholes or cracks occur as the contained solvent evaporates. In addition, powder flotation occurs due to differences in the solvent evaporation rate, and powder flotation is a cause of degraded electrode quality.

[0005] To solve the aforementioned problems, a dry manufacturing method for producing electrodes without using a solvent is known. The dry manufacturing method is performed by passing an electrode material powder containing an active material, a binder, and a conductive material through a plurality of calender rolls. The electrode material powder that has passed through the calender rolls is laminated and fixed to a current collector as a dry electrode film having a certain thickness.

[0006] In this regard, Korean Published Patent Application No. 10-2022-0052852 (powder for electrodes for manufacturing a dry electrode for a secondary battery, a method for manufacturing the same, a method for manufacturing a dry electrode using the same, a dry electrode, a secondary battery including the same, an energy storage device, and a dry electrode manufacturing device) has been disclosed.

[0007] The disclosed dry electrode manufacturing apparatus comprises: a blender for mixing composite raw materials including an active material, a conductive material, and a binder; a kneader for kneading the mixture to produce a mixture mass in order to fiberize the binder; a grinder for crushing the mixture mass to form a powder for electrodes; a calender for forming the powder for electrodes into a composite film; and a lamination roll for positioning the composite film on at least one surface of a current collector and laminating it.

[0008] The present invention aims to provide an electrode material rolling unit for a secondary battery that can rapidly and stably transport the electrode material and continuously supply an electrode material of uniform thickness without thickness variation due to good widthwise spreading properties of the electrode material.

[0009] The electrode material rolling unit for a secondary battery according to the present invention, as a means of solving the problem for achieving the above objective, comprises: a housing that provides support and passes through a current collector; a receiving module that is supported by the housing and receives electrode material powder provided from the outside and rolls it in a first step; a plurality of rolling rolls that receive the electrode material rolled in the first step from the receiving module, roll it, and transfer it to the current collector side; and a roll driving unit that rotates the rolling rolls at mutually different circumferential speeds, wherein the receiving module is composed of a first receiving roll and a second receiving roll that are rotated by the roll driving unit, and the diameters of the first and second receiving rolls are relatively smaller than the diameters of the rolling rolls.

[0010] In addition, the first receiving roll and the second receiving roll have the same diameter, the second receiving roll is adjacent to the end rolling roll, and the circumferential speed of the first receiving roll is relatively slower than the circumferential speed of the second receiving roll.

[0011] In addition, a plurality of grooves of a certain width and depth extending in the circumferential direction are formed on the outer surface of the second receiving roll.

[0012] In addition, a mirror plating layer is formed on the outer surface of the first receiving roll.

[0013] And, a plurality of the above rolling rolls are arranged side by side, and among the plurality of rolling rolls, the circumferential speed of the rolling roll in contact with the current collector is faster than twice the circumferential speed of the first receiving roll.

[0014] In addition, the circumferential speed of the roll from the first receiving roll to the rolling roll in contact with the current collector gradually increases.

[0015] The electrode material rolling unit for a secondary battery according to the present invention, as described above, can rapidly and stably transport the electrode material, and in particular, the electrode material has good spreadability in the width direction, allowing for the continuous supply of electrode material of uniform thickness without thickness variation.

[0016] FIG. 1 is a drawing illustrating a coating device to which an electrode material rolling unit for a secondary battery according to one embodiment of the present invention is applied.

[0017] Figure 2 is a drawing showing an enlarged view of a part of the electrode material rolling unit of Figure 1.

[0018] Figure 3 is a plan view of the coating apparatus of Figure 1.

[0019] FIG. 4 is a drawing for explaining the configuration and operating principle of a receiving roll applied to an electrode material rolling unit according to one embodiment of the present invention.

[0020] Figure 5 is a diagram illustrating the spreading principle of the electrode material formed through the receiving roll of Figure 4.

[0021] FIG. 6 is a drawing illustrating the appearance of an electrode material being coated on a current collector in an electrode material rolling unit according to one embodiment of the present invention.

[0022] Hereinafter, one embodiment according to the present invention will be described in more detail with reference to the attached drawings.

[0023] FIG. 1 is a drawing showing a coating device (10) to which an electrode material rolling unit (20) for a secondary battery according to one embodiment of the present invention is applied, FIG. 2 is a drawing showing an enlarged view of a part of the electrode material rolling unit of FIG. 1, and FIG. 3 is a plan view of the coating device of FIG. 1. In addition, FIG. 4 is a drawing to explain the configuration and operating principle of a receiving roll applied to an electrode material rolling unit according to one embodiment of the present invention, and FIG. 5 is a drawing to explain the spreading principle of an electrode material formed through the receiving roll of FIG. 4.

[0024] The electrode material rolling unit (20) of the present embodiment is installed in the electrode material coating device (10) and pressurizes the electrode material powder (P) supplied from the hopper (31) to a certain thickness, and then coats it onto the current collector (101).

[0025] The electrode material rolling unit (20) is mounted horizontally on the frame (11) and coats the electrode material onto a current collector (101) that passes between some rolling roll devices (29). The current collector (101) is a continuous material having a certain width and thickness, is guided by a guide roll (11a), and is transported along a transport path.

[0026] As described above, the rolling unit (20) comprises a housing (21), a receiving module, a plurality of rolling rolls (29), and a roll drive unit. The housing (21) is a structure that is horizontally supported on a frame (11) and is open vertically to allow a current collector (101) to pass through. The transport path of the current collector (101) passes through the housing (21). While the current collector (101) passes through the housing (21), electrode material (103) is coated on both sides of the current collector (101). (See FIG. 6)

[0027] Additionally, the housing (21) is provided with a linear guide (21a). Two linear guides (21a) extend in a straight line parallel to each other. The linear guides (21a) support the roll support block (22) so that it can slide. The roll support block (22) is capable of sliding movement while supported by the linear guide (21a). The roll support block (22) is a block-shaped member that is positionally adjustable and supported by the linear guide (21a). Two roll support blocks (22) form a pair, and between them, a rolling roll (29) and first and second receiving rolls (26, 27) are provided. The rolling roll (29) and the receiving rolls (26, 27) can rotate by receiving rotational force from the roll drive unit while supported by the roll support block (22). The receiving rolls (26, 27) are components of the receiving module described later.

[0028] A block pusher (23) is provided between the roll support blocks (22). The block pusher (23) is a hydraulic actuator mounted between each roll support block (22) and adjusts the spacing between adjacent roll support blocks (22). Adjusting the spacing of the block support blocks (22) means that the spacing between adjacent rolling rolls (29) and the first and second receiving rolls (26, 27) is adjusted. The reason for adjusting the spacing of the rolling rolls is to adjust the thickness of the electrode material (103) laminated on the current collector (101).

[0029] The block pusher (23) is operated by hydraulic pressure transmitted through the control valve (24). The control valve (24) is a proportional control valve, is connected to each block pusher (23), and transmits hydraulic pressure provided from the outside to the block pusher (23). The block pusher (23) operates by the transmitted hydraulic pressure to adjust the spacing of adjacent roll support blocks (22).

[0030] Meanwhile, the rolling rolls (29) receive the electrode material that has been rolled once from the receiving module, roll it, and transfer it to the current collector (101), and a plurality of rolling rolls (29) are arranged parallel to each other. The diameters of the plurality of rolling rolls (29) are the same. The rolling rolls (29) are received parallel to each other inside the housing (21), and as mentioned, both ends are supported by the roll support blocks (22). The rolling rolls are arranged parallel in the transverse direction and are spaced apart at intervals corresponding to the thickness of the electrode material to be manufactured. The spacing of the rolling rolls is adjusted by adjusting the spacing of the roll support blocks (22).

[0031] One of the rolling rolls is supported on a fixed plate (25). As shown in FIG. 1, the fixed plate (25) is a plate-shaped member fixed vertically to the housing (21) and fixes one rolling roll (29) in place. That is, it prevents the rolling roll from moving along the linear guide (21a). The rolling roll (27) fixed to the fixed plate (25) is only capable of rotational movement in place.

[0032] However, other rolling rolls other than the rolling roll (29) tied to the fixed plate (25) can be positioned along the longitudinal direction of the linear guide (21a). Therefore, based on the fixed rolling roll (29), if the left rolling rolls (29) in the drawing of FIG. 1 move to the right, the gap between the rolling rolls (29) narrows, allowing a thinner electrode material (103) to be formed. Similarly, if the right rolling rolls in the drawing of FIG. 1 are pushed to the left, the gap between the rolling rolls narrows, allowing the electrode material (103) to be formed thinner.

[0033] The rolling roll (29) fixed to the fixed plate (25) is a rolling roll located in the center among a plurality of rolling rolls. When there is an even number of rolling rolls, one of the two rolling rolls located at the very center is fixed to the fixed plate (25).

[0034] Meanwhile, the receiving module receives electrode material powder fed from the hopper (31) and performs primary rolling, and as shown in FIG. 1, is located at the opposite end with a plurality of rolling rolls (29) in between. The receiving module includes a first receiving roll (26) and a second receiving roll (27). The first receiving roll (26) and the second receiving roll (27) rotate in opposite directions while their ends are supported by the roll support block (22), and serve to receive electrode material powder (P) fed from the hopper (31) and perform primary rolling. The second receiving roll (27) is adjacent to the end rolling roll (29). It is adjacent to the rolling rolls (29) located at the left and right ends in the drawing. And the first receiving roll (26) is located on the opposite side of the rolling roll (29) with the second receiving roll (27) in between. The first receiving roll (26) and the second receiving roll (27) have the same diameter. Also, the diameters of the first and second receiving rolls are relatively smaller than the diameter of the rolling roll (29). Furthermore, the circumferential speed of the first receiving roll (26) is relatively slower than the circumferential speed of the second receiving roll (27). The circumferential speed of the second receiving roll (27) is less than twice as fast as the circumferential speed of the first receiving roll (26). Also, the circumferential speed of the rolling roll (29) is relatively faster than the circumferential speed of the second receiving roll (27). This will be explained later.

[0035] On the outer surface of the second receiving roll (27), a plurality of grooves (27a) of a certain width and depth are formed extending in the circumferential direction. The reason for applying the grooves (27a) is to form a plurality of grooves (103a in FIG. 5) on the cross-section of the electrode material that was rolled in the first step.

[0036] The groove (103a) is gradually filled in and disappears as the electrode material (103) passes through the rolling roll (29) in sequence and approaches the current collector (101). The groove (103a) acts to allow the rolled electrode material (103) to spread more efficiently in the width direction. That is, it serves to help the electrode material (103) expand more efficiently in the width direction when it is rolled.

[0037] As the electrode material (103) passes through the rolling roll (29), its thickness gradually decreases, and as the thickness decreases, its width increases. The electrode material (103) expands in the width direction. However, even if the electrode material (103) is rolled, the electrode material does not easily expand in the width direction. In other words, there is bound to be a difference between the density of the central part of the electrode material and the density of the outer part. Rolling alone does not maintain an even density between the central part and the outer part, and a difference in density occurs.

[0038] However, as described above, when a groove (103a) is formed in the electrode material that has been rolled once, as rolling proceeds, the groove (103a) is filled and the electrode material (103) spreads more uniformly in the width direction. As a result, the difference in density between the central part and the outer part is reduced, and the density distribution of the electrode material becomes more uniform. Consequently, the quality of the finally manufactured electrode sheet can be very good.

[0039] Additionally, a mirror plating layer (26a) is formed on the outer surface of the first receiving roll (26). The mirror plating layer (26a) makes the surface of the first receiving roll (26) smooth. Since the mirror plating layer (26a) is formed, the electrode material (103) that was rolled in the first step does not remain on the first receiving roll (26). Depending on the embodiment, a mirror plating layer may also be formed on the second receiving roll (27).

[0040] Meanwhile, the roll drive unit serves to rotate each rolling roll (29) and the first and second receiving rolls (26, 27) at mutually different circumferential speeds.

[0041] The roll drive unit rotates each rolling roll (29) and the first and second receiving rolls (26, 27) at mutually different speeds so that the electrode material (103) rolled first in the first and second receiving rolls (26, 27) passes through the rolling roll (29) in sequence and is coated onto the current collector (101). The roll drive unit includes a motor (33) and a coupling (35). The motor (33) corresponds one-to-one with the rolling roll (29) and the first and second receiving rolls (26, 27) and transmits rotational force through the coupling (35). The rotational force of the motor (33) is transmitted to the rolling roll and the first and second receiving rolls through the coupling (35).

[0042] FIG. 6 is a drawing illustrating the appearance of an electrode material (103) being coated on a current collector (101) in an electrode material rolling unit according to one embodiment of the present invention.

[0043] As described above, first and second receiving rolls (26, 27) are provided at both ends of a plurality of rolling rolls (29). As described above, the diameter of the first and second receiving rolls (26, 27) is smaller than the diameter of the rolling roll (29). The ratio of the diameters of the rolling roll (29) and the first and second receiving rolls (26, 27) can be varied.

[0044] In addition, the rotational speeds of the first and second receiving rolls (26, 27) and the rolling roll (29) are all different. First, the circumferential speed of the second receiving roll (27) is less than twice the rotational speed of the first receiving roll (26). The circumferential speed of the left and right end rolling rolls (29) is less than twice the circumferential speed of the second receiving roll (27).

[0045] Also, the circumferential speed of each rolling roll (29) is different, and the circumferential speed of the second rolling roll adjacent to the end rolling roll (29) is less than twice as fast as the speed of the left and right end rolling rolls (29). Also, the circumferential speed of the third rolling roll is less than twice as fast as the circumferential speed of the second rolling roll. Among the multiple rolling rolls, the circumferential speed of the rolling roll in contact with the collector (101) is the fastest. The rolling rolls adjacent to each other across the collector (101) rotate in opposite directions and have the same rotational speed. Consequently, the circumferential speed of the rolls from the first receiving roll to the rolling roll in contact with the collector gradually increases. However, the circumferential speed of the fastest rolling roll is less than twice the speed of the slowest first receiving roll.

[0046] As described above, since the speeds of the first and second receiving rolls and the rolling roll (29) differ, the electrode material that is rolled first in the first and second receiving rolls (26, 27) can pass through the rolling roll (29) and move toward the current collector (101). It is a known fact that a current collector passing through two rollers rotating at different speeds is conveyed by adhering to the outer surface of the relatively faster roller.

[0047] The electrode material rolling unit (20) for a secondary battery in this embodiment is installed in the electrode material coating device (10) and performs the function of rolling the electrode material powder (P) to a certain thickness and then coating it onto the current collector (101). This coating process is achieved by moving the electrode material (103) to the current collector using the first and second receiving rolls (26, 27) and a plurality of rolling rolls (29) while the current collector passes through the rolling unit (20).

[0048] The electrode material powder (P) is supplied through a hopper (31) and undergoes a first rolling process through a first receiving roll (26) and a second receiving roll (27). The first receiving roll (26) rotates at a relatively slower speed than the second receiving roll (27) and serves to support the powder, while the second receiving roll (27) rotates at a relatively faster speed to transport the electrode material to the rolling roll (29).

[0049] In particular, a groove (103a) is formed in the electrode material that is first rolled while passing through the first and second receiving rolls (26, 27). The groove (103a) acts to allow the electrode material to expand with a uniform density when rolled. That is, as the electrode material (103) repeatedly passes through the rolling roll (29), it gradually becomes thinner and wider, and the groove (103a) serves to offset the density difference that occurs at this time. As the electrode material passes through the rolling roll, the groove (103a) is filled and it expands evenly in the width direction, so the density difference between the central part and the outer part is reduced, and as a result, the electrode material is formed with a more uniform density.

[0050] Meanwhile, each rolling roll (29) rotates at a different speed and gradually adjusts the thickness and width of the electrode material. The receiving roll and the rolling roll each receive rotational force through a motor (33) and a coupling (35) and rotate at different speeds. Since the circumferential speed of the rolls gradually increases from the first receiving roll to the downstream rolling roll (the rolling roll in contact with the current collector), the electrode material can be rolled sequentially and moved toward the current collector.

[0051] Although the present invention has been described in detail through specific embodiments, the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the scope of the technical concept of the present invention.

[0052] In a coating device for coating electrode material on a current collector for a secondary battery, the electrode material is rolled, and the electrode material is stably conveyed while rolling, and the electrode material is supplied with a uniform thickness without thickness variation by ensuring good spreadability in the width direction, making it industrially usable.

Claims

1. Housing that provides support and passes through the entire house; A receiving module supported by a housing and receiving electrode material powder supplied from the outside and rolling it in a first step; A plurality of rolling rolls that receive a primary rolled electrode material from a receiving module, roll it, and transfer it to the current collector side; and It includes a roll drive unit that rotates the above rolling rolls at mutually different circumferential speeds, and The above receiving module is composed of a first receiving roll and a second receiving roll that rotate by a roll drive unit, and the diameters of the first and second receiving rolls are provided to be relatively smaller than the diameter of the rolling roll, characterized in that they are an electrode material rolling unit for a secondary battery.

2. In Paragraph 1, The first receiving roll and the second receiving roll have the same diameter, and the second receiving roll is adjacent to the end rolling roll, and A rolling unit for electrode materials for a secondary battery, characterized in that the circumferential speed of the first receiving roll is relatively slower than the circumferential speed of the second receiving roll.

3. In Paragraph 2, A rolling unit for electrode materials for a secondary battery, characterized in that a plurality of grooves of a certain width and depth extending in the circumferential direction are formed on the outer surface of the second receiving roll.

4. In Paragraph 3, A rolling unit for electrode materials for a secondary battery, characterized in that a mirror-plated layer is formed on the outer surface of the first receiving roll.

5. In Paragraph 2, A plurality of the above rolling rolls are arranged side by side, and A rolling unit for electrode material for a secondary battery, characterized in that, among a plurality of rolling rolls, the circumferential speed of the rolling roll in contact with the current collector is fast at a speed less than or equal to twice the circumferential speed of the first receiving roll.

6. In Paragraph 5, A rolling unit for electrode materials for a secondary battery, characterized in that the circumferential speed of the roll from the first receiving roll to the rolling roll in contact with the current collector gradually increases.

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