JPH0640488B2 - Method for producing positive electrode for spiral lithium battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a positive electrode used in a spiral lithium battery.

<< Prior Art >> A method for manufacturing a positive electrode in a spiral lithium battery is
It consists of the following steps.

A step of continuously applying a positive electrode material mixture on both sides while unwinding a net-shaped current collector forming material wound in a roll and drying to form a sheet-shaped positive electrode material.

This positive electrode material is cut into a predetermined size, a pair of rotating brushes are pressed against the positive electrode mixture on both sides at the processing position, and the positive electrode mixture is scraped into a band shape by rotating to move the positive electrode mixture to form a current collector. The process of exposing a part of the material in a strip shape.

A step 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, the rotary brush is significantly worn, and the rotary brush must be replaced frequently.

Further, when the rotating brush is strongly pressed toward the positive electrode mixture, even the positive electrode current collector may be damaged, and in some rare cases, the positive electrode current collector may be cut.

On the contrary, when the pressing force is small, the rotating brush wears little, but the positive electrode mixture cannot be sufficiently scraped off, and its adjustment is a fairly minute work. The inconvenience occurred frequently and caused the line to be frequently stopped.

As a method for solving this kind of drawback, for example, an ultrasonic processing technique disclosed in Japanese Patent Laid-Open No. 63-40253 is 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 technical problems described below.

<Problems to be Solved by the Invention> In the method disclosed in the above publication, as a concrete means for removing the positive electrode mixture by ultrasonic vibration, the tip of an ultrasonic horn is pressed against the positive electrode mixture. The horn is vibrated with a predetermined amplitude, and the positive electrode mixture at the abutting site is crushed according to this vibration, exposing the current collector, but the shape of the tip of the ultrasonic horn is flat. If you use this, the powder of the crushed positive electrode mixture will adhere to the contact surface of the horn, and vibration will be applied with the powder attached, so the crushed positive electrode mixture and powder that have been separated once However, there was a problem that they adhere to the current collector again.

As described above, since the powder of the positive electrode mixture reattached by ultrasonic vibration is attached under the pressure applied by the impact of ultrasonic waves, it is difficult to remove it, and the current is collected in the state where the powder is attached. When attempting to weld the lead plate to the exposed part of the body, there were problems such as sparks.

This invention has solved the above-mentioned drawbacks, and in a method of crushing and removing a part of the positive electrode mixture by an ultrasonic horn instead of a rotating brush and exposing the lead plate welded portion of the current collector in a strip shape. An object of the present invention is to provide a method for manufacturing a positive electrode for a spiral lithium battery, which can prevent the redeposition of the positive electrode mixture.

<Means for Solving the Problems> In order to achieve the above object, the present invention is to move a positive electrode material obtained by laminating double-sided positive electrode mixture of a net-shaped current collector relative to an ultrasonic horn. In a method for producing a positive electrode for a spiral lithium battery, the positive electrode mixture is partially removed by ultrasonic treatment, the current collector is exposed in a strip shape, and a lead plate is welded to the exposed portion. The tip shape of the ultrasonic horn used for the ultrasonic treatment is formed into a comb tooth shape in which unevenness is continuous along the moving direction of the positive electrode material, and a pedestal installed opposite to the ultrasonic horn. A concave groove for accommodating the stripped piece of the positive electrode mixture was formed on the side.

In addition, the protrusions forming the tooth-shaped tip end portions of the comb may be sequentially formed in the longitudinal direction in a taper arrangement along the moving direction of the positive electrode material.

Further, the convex portions forming the tooth-shaped tip portion of the comb are driven by independent ultrasonic horns, respectively, and are vibrated with different amplitudes so that the amplitude gradually increases along the moving direction of the positive electrode material. Good.

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

<Operation> By selecting an appropriate amplitude, the surface of the positive electrode material mixture that faces the ultrasonic horn in opposition is subjected to ultrasonic vibration, and the convex portion that forms the tooth-like unevenness of the comb is formed at the tip of the ultrasonic horn. The fine powder crushed by the edges of the positive electrode and floated on the surface of the positive electrode mixture due to the crushing is accommodated in the concave portion adjacent to the convex portion, and the redeposited crushed positive electrode mixture is prevented.

Also, when the convex portions are sequentially formed in a long length in a taper arrangement along the moving direction of the positive electrode material, the crushing depth due to vibration becomes larger in the subsequent convex portions, and the crushing state is within a reasonable range with a constant amplitude. Can be expanded in sequence.

Furthermore, even when the convex portions are driven by independent ultrasonic horns and are vibrated at different amplitudes so that the amplitude increases sequentially along the moving direction of the positive electrode material, the crushed state is the same as above. It can be expanded sequentially.

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

<< Embodiment >> An embodiment of the present invention will be described in detail below with reference to 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 current collector 2 coated with a positive electrode mixture 3 on both upper and lower surfaces thereof, solidified to have a predetermined thickness, and then cut into predetermined dimensions.

The positive electrode material 1 is stripped of the positive electrode material mixture 3 in the central portion thereof in a band shape orthogonal to the longitudinal direction of the positive electrode material 1 by the ultrasonic processing apparatus shown in FIG. The lead plate welding surface 2a of No. 2 is exposed.

The processing device positions and fixes the positive electrode material 1 on the upper surface, and is arranged above and below the processing position of the frame-shaped feed table 10 that reciprocates between the processing standby position and the processing position along the guide rail 11. The ultrasonic horn 12 and the pedestal 14 thereof, the air blowing device 16 arranged at the rear of the ultrasonic horn 12, and the pair of rotary brushes 18 at the rearmost position facing the position where the table 10 is sandwiched. I have it.

The tip shape of the ultrasonic horn 12 is constant in the width direction as shown in FIGS. 4 and 5, and the toothed protrusions 12a and recesses 12b of the comb are continuous in the moving direction of the positive electrode material 1. In addition, the vertical length of each convex portion 12a is a taper-like arrangement and sequentially protrudes toward the lower side.

The lengths of the protrusions 12a do not necessarily have to be tapered and may be the same.

A groove 14a for receiving a flaking piece is formed in the center of the receiving base 14 so as to face each of the convex portions 12a.

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

In the above configuration, the positive electrode material 1 is ultrasonically processed in the following order.

First, at the processing standby position, the positive electrode material 1 cut to a predetermined size on the feed table 10 is clamped in a state of being installed orthogonally to the feed direction, and then moved forward to the processing position, the positive electrode material 1 is cradleed. It is located between 14 and the ultrasonic horn 12.

In this state, lower the ultrasonic horn 12 while vibrating it,
While being in contact with or close to the surface of the positive electrode mixture 3, it touches the edge of the convex portion 12a that first comes into contact with the positive electrode mixture 3 and receives the vibration thereof, so that it is crushed with a relatively small force. The flaking powder generated by the crushing falls into the groove 14a of the pedestal 14 on the lower side.

Further, on the upper side, a part of the crushed exfoliated powder is separated, and the separated powder is provided in the concave portion 12 adjacent to the convex portion 12a.
It is housed inside b and its redeposition is prevented.

In this state, as the table 10 advances, the next convex portion 12a
The tip edge of the contact part comes into contact with the part that has already been vibrated, and the crushing operation is performed at a contact position deeper than the above. Then, as the table 10 advances, the crushing portions are continuous with the width corresponding to the width of each convex portion 12a, and the crushing force deeply works toward the rear side, and the crushing proceeds sequentially without difficulty.

After the crushing work by the ultrasonic horn 12 is completed, the flaking pieces remaining on the surface are blown away by the air blowing from the next air blowing device 16 in accordance with the forward movement of the table 10.

Next, in the crushed portion formed in the groove shape, the upper and lower rotating brushes 18 rotate along the groove width, and as the table 10 advances, fine irregularities inside the groove are removed and smoothed.

After advancing to the most advanced position, the table 10 moves backward from the processing position and returns to the processing standby position, and the breaking work and the post-processing work are completed.

As a matter of course, the air blowing device 16 is stopped when the table 10 is retracted, and the ultrasonic horn 12 stands by at the raised position so as not to obstruct the passage.

When the positive electrode material 1 is unclamped from the table 10 at the processing standby position, the positive electrode material 1 as an intermediate product can be obtained in which the lead plate mounting surface 2a is exposed in a strip shape at the center as shown in FIG.

In addition, the optimum descending width for the above ultrasonic processing is 20 to 100 μm.
If m is below the lower limit, sufficient rupture work cannot be expected, and if it is above the upper limit, other parts than the rupture will also be affected. Ultrasonic processing is desirable.

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 to obtain 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 surface of the positive electrode with a separator and spirally wound, and the spiral negative electrode is housed in a case, and the lead plates protruding from the positive electrode and the lithium negative electrode are covered with the case and the opening of the case, respectively. The spiral type lithium battery is completed by adjoining the terminal plate.

Next, FIG. 6 shows a second embodiment of the present invention. The convex portions 20a-1, 20a-2, ..., Which constitute the tooth-shaped tip portion of the comb of the ultrasonic horn in the figure, respectively, constitute the tip portions of different ultrasonic horns, and the convex portion 20 on the most distal side is provided.
The amplitude on the a-1 side is small, and the amplitude is sequentially increased toward the next convex portion 20a-2 side, so that the driving is performed with different amplitudes.

Even in this embodiment, the positive electrode mixture 3 is crushed with a large amplitude in the same manner as described above. Therefore, similarly to the above, the crushing force is crushed toward the rear side, and the crushing proceeds sequentially without difficulty. .

Also in this embodiment, it is necessary to set the amplitude range to 20 to 100 μm and set the amplitude of each convex portion to be large successively within that range.

In addition, although the positive electrode material 1 to be processed is moved in the above-mentioned embodiment, the ultrasonic horn may be moved while fixing the positive electrode material 1.

The air spraying device 16 and the rotating brush 18 are auxiliary devices and are not always necessary for carrying out the present invention.

<< Effects of the Invention >> As described in detail above with reference to the embodiments, according to the method for producing a positive electrode for a spiral lithium battery according to the present invention, the following advantages are obtained as compared with the conventional mixture removing work by ultrasonic vibration. is there.

By selecting an appropriate amplitude, the surface of the positive electrode mixture that is in contact with the ultrasonic horn is continuously joined by the edges of the protrusions that form the tooth-like irregularities of the comb formed at the tip of the ultrasonic horn under ultrasonic vibration. The crushing efficiency is improved as compared with the case where the tip has a surface shape.

Further, the fine powder separated on the surface side of the positive electrode mixture by crushing is contained in the concave portion adjacent to the convex portion, and its re-adhesion is prevented.

As described in claim 2, when the protrusions are sequentially formed in a taper array along the moving direction of the positive electrode material, the crushing depth due to vibration becomes larger in the subsequent protrusions, and a constant amplitude is obtained. The crushed state can be gradually expanded within a reasonable range.

Further, as described in claim 3, in the case where the convex portions are driven by independent ultrasonic horns and are vibrated with different amplitudes so that the amplitude gradually increases along the moving direction of the positive electrode material. Also, similarly to the above, the crushed state can be gradually expanded.

With the method according to the fourth aspect, the flaking pieces generated by the removing work can be completely removed, and the fine unevenness on both sides in the width direction can be smoothed by the buffing work.

[Brief description of drawings]

1 is a partial 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 apparatus, FIG. 3 is a perspective view showing the shape of the positive electrode material after ultrasonic processing, FIG. FIG. 5 is an enlarged view of part A of FIG. 2, FIG. 5 is a sectional view taken along line IV-IV of FIG. 3, and FIG.
The drawing is a partially enlarged view showing the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Positive electrode material, 2 ... Positive electrode current collector 2a ... Lead plate welding surface 3 ... Positive electrode mixture, 12 ... Ultrasonic horn 12a, 20a-1 -... convex part 12b ... concave part, 16 ... … Air blowing device 18 …… Buffing roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Katsuno 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (56) Reference JP-A-58-51467 (JP, A)

Claims (4)

[Claims] 1. A positive electrode material obtained by laminating a positive electrode mixture on both sides of a net-shaped current collector is moved relatively to an ultrasonic horn while the positive electrode mixture is partially removed by ultrasonic treatment. In the method for manufacturing a positive electrode for a spiral lithium battery, which comprises exposing the current collector in a strip shape and then welding a lead plate to the exposed portion, the tip shape of the ultrasonic horn used for the ultrasonic treatment is: A concave groove for accommodating the stripped piece of the positive electrode mixture is formed on the pedestal side that is installed below the ultrasonic horn so as to face it, while the unevenness is formed in a comb tooth shape along the moving direction of the positive electrode material. A method for producing a positive electrode for a spiral lithium battery, which is characterized by being formed. 2. The convex portion forming the tooth-shaped tip end portion of the comb is formed in a longitudinally long direction in a taper-like arrangement sequentially along the moving direction of the positive electrode material. The method for producing a positive electrode for a spiral lithium battery according to 1. 3. The convex portions forming the tooth-shaped tip portion of the comb are driven by independent ultrasonic horns, respectively.
The method for manufacturing a positive electrode for a spiral lithium battery according to claim 1, wherein the positive electrode material is oscillated with different amplitudes so that the amplitude gradually increases along the moving direction of the positive electrode material. 4. After removing the positive electrode mixture with an ultrasonic horn, air is blown to the exposed portion of the current collector, and then brushing is applied to the exposed portion, and the positive electrode mixture remaining on the exposed portion is removed. The method for producing a positive electrode for a spiral lithium battery according to claim 1, wherein the exfoliated pieces of the agent are removed.