JPH01251555A - Manufacture of positive electrode for spiral lithium cell - Google Patents

Abstract

PURPOSE:To prevent the re-sticking of the crushed positive electrode black mix by forming the tip shape of a ultrasonic horn into the comb teeth shape with continued irregularities along the shift direction and forming a recess groove storing peeled pieces of the positive electrode black mix on the receiving bed side below it. CONSTITUTION:The positive electrode black mix 3 laminated on both faces of a net-shaped current collector is relatively moved and partially removed by the ultrasonic processing to expose the current collector in a belt shape, then a lead plate is welded to the exposed portion 2a to manufacture a positive electrode for a cell. The tip shape of a ultrasonic horn 12 used for the ultrasonic processing is formed into the comb teeth shape with continued irregularities along the shift direction, a recess groove 14a storing peeled pieces of the positive electrode black mix 3 is formed on the receiving bed 14 side installed below the ultrasonic horn 12 facing it. The fine powder floated on the surface of the positive electrode black mix 3 by crushing is stored in recesses 12b adjacent to projections 12a, the re-sticking of the crushed positive electrode black mix can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a positive electrode used in a spiral-type lithium battery.

(Prior art) The method for manufacturing a positive electrode in a spiral lithium battery is as follows:
It consists of the following steps.

■The process of continuously applying positive electrode mixture to both sides while unwinding the net-like current collector forming material wound into a roll, drying it, and making it uniform in thickness to form a sheet-like positive electrode material.

■This positive electrode material is cut to a predetermined size, and a pair of rotating brushes are pressed against the positive electrode mixture on both sides at the processing position, and by rotating and moving relative to each other, the positive electrode mixture is scraped off in a band shape to form a current collector. A process in which a part of the forming material is exposed in a band-like manner.

(2) A process of spot welding a positive electrode lead plate to the exposed surface of the current collector to complete the positive electrode.

However, according to this manufacturing method, in the scraping step (2) above, the rotating brush was significantly worn, and the rotating brush had to be replaced frequently.

Furthermore, when the rotating brush is strongly pressed against the positive electrode mixture side, the positive electrode current collector may also be damaged, and in rare cases, the positive electrode current collector has been used to be cut.

On the other hand, if the pressing force is small, the amount of wear on the rotating brush is small, but the positive electrode mixture cannot be scraped off sufficiently, and the adjustment is a very delicate work. The above-mentioned inconvenience occurred frequently, causing the line to have to be stopped frequently.

As a method for solving this type of drawback, an ultrasonic processing technique disclosed in, for example, Japanese Patent Laid-Open No. 63-40253 has been proposed.

According to this ultrasonic processing method, a predetermined portion of the positive electrode mixture is removed by applying ultrasonic vibration to the positive electrode mixture, but this method has the following technical problems.

(Problem to be Solved by the Invention) In the method disclosed in the above publication, the specific means for removing the positive electrode mixture by ultrasonic vibration is to press the tip of an ultrasonic horn against the positive electrode mixture. , which applies vibration to the horn at a predetermined amplitude, and in response to this vibration, the positive electrode mixture at the contact area is crushed and the current collector is exposed, but the tip of the ultrasonic horn is flat. If you use a 100% solid cathode mixer, the crushed positive electrode mixture powder will adhere to the contact surface of the horn, and vibration will be applied with the powder attached, so that the crushed and partially separated positive electrode mixture powder will be removed. There was a problem in that the particles adhered to the current collector again.

In this way, the positive electrode mixture powder that has been redeposited by ultrasonic vibration is attached under pressure due to the ultrasonic impact, so it is difficult to remove it, and it is difficult to collect the current with the powder attached. When attempting to weld a lead plate to an exposed part of the body, there were problems such as sparks being generated.

This invention solves the above-mentioned drawbacks, and uses an ultrasonic horn instead of a rotating brush to crush and remove a part of the positive electrode mixture and expose the welded part of the lead plate of the current collector in a band shape. The object of the present invention is to provide a method for manufacturing a positive electrode for a spiral type lithium battery, which can prevent re-deposition of a positive electrode mixture.

(Means for Solving the Problem) In order to achieve the above object, the present invention partially removes the positive electrode mixture laminated on both sides of a net-like current collector by ultrasonication while relatively moving it, In the method for manufacturing a positive electrode for a spiral type lithium battery, in which the current collector is exposed in a band shape and then a lead plate is welded to the exposed portion, the tip shape of the ultrasonic horn used for the ultrasonic treatment is adjusted in the direction of movement. A concave groove was formed in the shape of a comb in which concavities and convexities continued along the ridge, and a concave groove for accommodating flaked pieces of the positive electrode mixture was formed on the pedestal side opposite to the lower part of the ultrasonic horn.

Further, the convex portions constituting the tooth-like tip portions of the comb may be formed in a tapered arrangement and sequentially elongated in the vertical direction along the moving direction of the object to be removed.

Furthermore, the convex parts constituting the tooth-shaped tip of the comb are driven by independent ultrasonic horns, and vibrated at different amplitudes so that the amplitude increases sequentially along the moving direction of the object to be removed. You can.

After the exposed portion of the current collector is blown with air after ultrasonic processing, brushing treatment may be performed to remove the positive electrode mixture remaining in the portion.

(Function) By selecting an appropriate amplitude, the surface of the positive electrode mixture that comes into contact with the ultrasonic horn can be transformed into a convex portion that forms the comb tooth-like unevenness formed at the tip of the ultrasonic horn by receiving ultrasonic vibrations. The fine powder that is crushed by the edges of the positive electrode mixture and floated to the surface of the positive electrode mixture due to the crushing is accommodated in the four parts adjacent to the convex parts, thereby preventing the crushed positive electrode mixture from re-adhering.

Furthermore, if the convex portions are formed in a tapered arrangement in order along the direction of movement of the positive electrode or horn, the crushing depth due to vibration will become larger in subsequent convex portions, making it impossible to force the crushing state with a constant amplitude. You can gradually expand the range.

Furthermore, even if the convex parts are driven by independent ultrasonic horns and vibrated with different amplitudes so that the amplitude increases sequentially along the moving direction of the positive electrode,
Similar to the above, the crushed state can be expanded sequentially.

The flaked pieces are completely removed by air blowing, and the fine unevenness of the positive electrode mixture on both sides of the removed portion in the width direction can be smoothed by brushing.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 shows the positive electrode material 1 before ultrasonic processing.

The positive electrode material 1 in the figure is a strip-shaped material that is obtained by coating the upper and lower surfaces of a net-like current collector 2 with a positive electrode mixture 3, solidifying it, forming it to a predetermined thickness, and then cutting it into a predetermined size.

As shown in FIG. 3, the positive electrode mixture 3 in the center of the positive electrode material 1 is removed in a strip shape perpendicular to the longitudinal direction of the positive electrode material 1 using the ultrasonic processing device shown in FIG. 2 lead plate welding surface 2a is exposed.

The processing device has a frame-shaped feed table 10 that positions and fixes the positive electrode material 1 on the upper surface, and that moves back and forth between a special processing machine position and a processing position along a guide rail 11, and a frame-shaped feed table 10 that is arranged above and below the processing position of the feed table 10. The ultrasonic horn 12 and its holder are connected to a stand 14, an air blowing device 16 is placed at the rear of the ultrasonic horn 12, and a pair of rotating units located at the rearmost part of the ultrasonic horn 12 are located opposite to each other in a position sandwiching the table 10. A brush 18 is provided.

As shown in FIGS. 4 and 5, the shape of the tip of the ultrasonic horn 12 is constant in the width direction, and has a comb-like convex portion 12a and a concave portion 12b that are continuous in the movement processing direction of the positive electrode material 1. Further, the length of each convex portion 12a in the vertical direction is arranged in a tapered shape and sequentially protrudes toward the lower side.

Note that the lengths of the convex portions 12a do not necessarily need to be tapered and may be the same length.

A groove 14a for receiving flakes is formed in the center of the receiver stand 14, facing each of the convex portions 12a.

Further, the reference numeral 15 shown in FIG. 5 is a temporary holding member for the positive electrode material 1, and it is desirable that the groove size X of this holding plate be approximately the same as the groove size X' of the holding plate 14a.

In the above configuration, the positive electrode material 1 is subjected to ultrasonic processing in the following order.

First, the positive electrode cable material 1 cut to a predetermined size is clamped on the feeding table 10 at a special processing machine position and set perpendicular to the feeding direction, and then when it is advanced to the processing position, the positive electrode material 1 is The receiver is located between the platform 14 and the ultrasonic horn 12.

In this state, the ultrasonic horn 12 is lowered while being vibrated,
While in contact with or in close proximity to the surface of the positive electrode mixture 3, the edge of the convex portion 12a that first contacts the positive electrode mixture 3 is touched, and by receiving the vibration, it is crushed with a relatively small force. The powder of flakes generated by the crushing falls into the groove 14a of the tray 14 on the lower side.

Further, a part of the crushed flake powder is separated on the upper side, and the separated powder is transferred to the recess 12b adjacent to the projection 12a.
and is housed inside the body to prevent its reattachment.

In this state, as the table 10 moves forward, the next convex portion 12a
The leading edge of the contact point contacts the area that has already been subjected to vibration, and performs a crushing operation at a deeper contact position than the above point.

As the table 10 moves forward, this crushing location continues with a width corresponding to the width of each convex portion 12a, and the crushing force acts deeper toward the rear side, and the crushing progresses smoothly one after another.

After the crushing operation by the ultrasonic horn 12 is completed, the flakes remaining on the surface are blown off and removed by the next air blow from the device 16 as the table 10 moves forward.

Next, the upper and lower rotating brushes 18 rotate along the width of the groove, and as the table 10 moves forward, the crushed portion formed in the groove is smoothed by removing minute irregularities inside the groove.

After the table 10 advances to the most advanced position, it then retreats from the machining position and returns to the special machining machine position to complete the breaking work and post-processing work.

As a matter of course, the air blowing device 16 stops when the table 10 retreats, and the ultrasonic horn 12 waits at the raised position so as not to obstruct passage.

If the positive electrode material 1 is unclamped from the table 10 at the special processing machine position, the positive electrode cable material 1 as an intermediate product with the lead plate attachment surface 2a exposed in the center as shown in FIG. 3 can be obtained.

The optimum amplitude for the above ultrasonic processing is 20 to 100μ.
m, and if it falls below the lower limit, sufficient breaking work cannot be expected, and if it exceeds the upper limit, it will affect areas other than the breaking point, so within the above amplitude range. Ultrasonic processing is preferable.

After the ultrasonic processing is completed, a lead plate (not shown) is integrally welded to the lead plate welding surface 2a of the positive electrode material 1 by spot welding, thereby obtaining a positive electrode in which the lead plate is integrated in the center of the current collector 2.

Then, a lithium negative electrode is laminated on the back side of this positive electrode with a separator interposed between them, and is spirally wound.This is housed in a case, and the lead plates protruding from the positive electrode and lithium negative electrode are respectively placed in the case and the opening of the case is covered. By connecting it to the terminal board, a spiral-shaped lithium battery is completed.

Next, FIG. 6 shows a second embodiment of the present invention. The protrusions 20a-1, 20a-2, etc., which constitute the tooth-shaped tips of the combs of the ultrasonic horns in the figure, respectively constitute the tips of separate ultrasonic horns, and the protrusions 2 on the most distal side
Drives are performed with different amplitudes such that the amplitude on the 0a-1 side is small and the amplitude increases sequentially as it approaches the next convex portion 20a-2 side.

In this embodiment as well, the positive electrode mixture 3 is crushed with successively larger amplitudes in the same manner as described above, so that the further the rear side is crushed, the more crushing force is applied, and the crushing progresses smoothly. .

Further, in this embodiment as well, it is necessary to set the amplitude range to 20 to 100 μm, and to sequentially increase the amplitude of each convex portion within that range.

In the above embodiment, the positive electrode material 1 to be processed was moved, but it may be fixed while the ultrasonic horn is moved.

The air blowing device 162 and the rotating brush 18 are auxiliary and are not necessarily required to carry out the present invention.

(Effects of the Invention) As explained in detail in the examples above, the method for manufacturing a positive electrode for a spiral type lithium battery according to the present invention has the following advantages compared to the conventional mixture removal operation using ultrasonic vibration. be.

By selecting an appropriate amplitude, the surface of the positive electrode mixture that comes into contact with the ultrasonic horn can be made continuous by the edges of the convex part that constitutes the comb tooth-like unevenness formed at the tip of the ultrasonic horn by receiving ultrasonic vibrations. Since the tip is crushed in a flat manner, the crushing efficiency is improved compared to the case where the tip has a planar shape.

Further, the fine powder separated on the surface side of the positive electrode mixture due to crushing is accommodated in the recesses adjacent to the projections, and re-adhesion thereof is prevented.

As shown in claim 2, when the convex portions are formed to be long in a tapered arrangement along the movement direction, the crushing depth due to vibration becomes larger in the subsequent convex portions, and the crushing state is maintained at a constant amplitude. can be gradually expanded within a reasonable range.

Further, as shown in claim 3, even if the convex portions are driven by independent ultrasonic horns and vibrated with different amplitudes so that the amplitudes increase sequentially along the moving direction, the Similarly, it is possible to wave the crushed state sequentially.

By using the method according to claim 4, flakes generated by the removal work can be completely removed, and minute irregularities on both sides in the width direction can be smoothed by the puffing work.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view of a positive electrode material to which the present invention is applied, FIG. 2 is a side view of an ultrasonic processing device, FIG. 3 is a perspective view showing the shape of the positive electrode material after ultrasonic processing, and FIG. The figure is an enlarged view of part A in FIG. 2, FIG. 5 is a sectional view taken along the line IV--IV in FIG. 3, and FIG. 6 is a partially enlarged view showing a second embodiment of the present invention. 1... Positive electrode material 2... Positive electrode current collector 2a...
・Lead plate welding surface 3...Positive electrode mixture 12...Ultrasonic horn 12
a, 20a-1~...Convex portion 12b...Concave portion 16...Air blowing device 18...Puffing roller

Claims (4)

[Claims] (1) After the positive electrode mixture laminated on both sides of the net-like current collector is partially removed by ultrasonication while relatively moving, and the current collector is exposed in a band shape, this exposed portion is removed. In a method for manufacturing a positive electrode for a spiral-type lithium battery, in which a lead plate is welded to A method for manufacturing a positive electrode for a spiral type lithium battery, characterized in that a groove for storing flakes of the positive electrode mixture is formed on a pedestal side oppositely installed below an ultrasonic horn. (2) The spiral shape according to claim 1, wherein the convex portions constituting the tooth-shaped tip portion of the comb are formed in a sequentially tapered array and long in the vertical direction along the moving direction. A method for manufacturing a positive electrode for lithium batteries. (3) The convex parts constituting the tooth-like tip of the comb are each driven by an independent ultrasonic horn, and vibrate at different amplitudes so that the amplitude increases sequentially along the moving direction. 2. The method for manufacturing a positive electrode for a spiral-type lithium battery according to claim 1. (4) After removing the positive electrode mixture using an ultrasonic horn, air is blown onto the exposed part of the current collector, and then the area is brushed to remove the positive electrode mixture remaining in the exposed part. 4. The method for manufacturing a positive electrode for a spiral-type lithium battery according to claim 1, wherein flakes are removed.