JP3665659B2 - Paste filling device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a paste-type electrode having a structure in which a paste containing an active material is filled in a current collector, and more particularly to a method for producing a paste-type electrode with an improved process of filling a current collector with paste. .
[0002]
[Prior art]
Alkaline secondary batteries using a hydrogen storage alloy for the negative electrode are expected as batteries that can meet the demand for higher capacity of secondary batteries in recent years. In addition, a nickel-metal hydride secondary battery using this hydrogen storage alloy as a negative electrode and using nickel hydroxide as a positive electrode active material has a negative electrode capacity similar to that of the positive electrode, similar to a nickel cadmium secondary battery using a cadmium compound as a negative electrode active material. Has a larger structure. For this reason, since the said nickel hydride secondary battery can make the said negative electrode absorb the oxygen which generate | occur | produces in the said positive electrode at the time of an overcharge, sealing is possible.
[0003]
As a method for producing a negative electrode using a hydrogen storage alloy, a paste is prepared by kneading a hydrogen storage alloy powder, a polymer binder such as polytetrafluoroethylene and carboxymethylcellulose, and a conductive material, There is known a method of manufacturing a negative electrode by filling a paste into a current collector such as a punched metal, drying it, pressurizing it, and cutting it into a desired size. The polytetrafluoroethylene is added to the paste in order to increase the strength of the negative electrode.
[0004]
In such a manufacturing method, the step of filling the current collector with the paste is conventionally performed using a paste filling apparatus shown in FIG. The paste filling apparatus includes a paste container 31 having a long hole 31a at the bottom. The paste filling amount adjusting member 32 has a rectangular slit 33 and a tapered elongated hole 34 formed so as to communicate with the slit 33. The paste filling amount adjusting member 32 having such a structure is disposed above the container 31. The pair of rollers 35 a and 35 b are disposed above the container 31. In such an apparatus, the paste is contained in the container 31, the roller 35a is rotated counterclockwise, and the roller 35b is rotated clockwise. A band-shaped punched metal S is inserted into the container 31 through the elongated hole 31a and moved upward. When the pair of rollers 35a and 35b rotates, the paste moves closer to the periphery of the band-shaped punched metal S due to this rotation, and the pressure of the paste in the vicinity of the band-shaped punched metal increases. Is filled with the paste. After the band-shaped punched metal S filled with the paste passes through the slot 33 of the filling amount adjusting member 32 and then passes through the slit 33, the extra paste applied by the slit 33 is scraped off. The punched metal S is filled with a predetermined amount of paste.
[0005]
However, in the filling process, when the paste in the container is brought near the punched metal S by the pair of rollers, the pressure of the paste locally increases, so that shear stress is applied to the paste. Since the polytetrafluoroethylene contained in the paste is fiberized by this shear stress, there is a problem that the viscosity of the paste increases as the filling process proceeds. As a result, the paste is less likely to move around the band-shaped punched metal, so that the amount of paste filled in the band-shaped punched metal decreases as the filling process proceeds, and the yield decreases. There was a point. For this reason, if the roller is removed from the apparatus, it becomes difficult to increase the paste pressure in the vicinity of the band-shaped punched metal, so that a sufficient amount of paste cannot be filled in the band-shaped punched metal. There was a point.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a paste-type electrode manufacturing method and a paste filling apparatus capable of uniformly filling a strip-shaped current collector with a paste.
[0007]
[Means for Solving the Problems]
The paste filling apparatus according to the present invention is a paste filling apparatus in which a paste containing an active material and polytetrafluoroethylene is used.
A paste container having a current collector insertion hole on the bottom surface;
Paste supply means for supplying the paste into the container;
Two holding plates disposed at a distance from each other in the container;
A paste filling amount adjusting member having a slit that is disposed between the two holding plates and through which the band-shaped current collector inserted from the current collector insertion hole passes;
Paste liquid surface for making the paste liquid surface between the inner surface of the container and each holding plate higher than the paste liquid surface in the slit filled with the paste and keeping the difference between the liquid surfaces constant With height control means
It is characterized by comprising.
[0008]
Examples of the active material include a hydrogen storage alloy, a cadmium compound, and nickel hydroxide.
Examples of the strip-shaped current collector include a two-dimensional structure such as a punched metal, an expanded metal, and a wire net, and a three-dimensional structure such as a foam metal and a net-like sintered metal fiber.
[0010]
[Action]
According to the method for producing a paste-type electrode of the present invention, a paste containing an active material and polytetrafluoroethylene is accommodated in a container, and a paste filling amount adjusting member is filled in the container with the paste. It is possible to increase the pressure of the entire paste uniformly by applying a constant pressure to the paste from the outside. As a result, since shear stress is not applied to the paste, it is possible to prevent the polytetrafluoroethylene in the paste from becoming fibers and maintain the viscosity of the paste at a desired value. Accordingly, the band-shaped current collector can be uniformly filled with the paste by inserting the band-shaped current collector into the container through the current collector insertion hole and passing through the slit of the filling amount adjusting member. Yield can be improved. Moreover, since a filling process can be continued over a long period of time, the working efficiency of the filling process can be improved.
[0011]
Further, according to the paste filling apparatus according to the present invention, the paste filling amount adjusting member is disposed in the container so that the slit is filled with the paste, and the paste liquid surface contacting the inner surface of the container by the paste liquid surface control means is provided. By making it higher than the paste liquid level located in the slit of the filling amount adjusting member, the pressure of the paste in the container can be increased substantially uniformly. For this reason, it is possible to prevent a shear stress from being applied to the paste. Moreover, the pressure applied to the paste can be kept constant by keeping the difference in liquid level constant by the paste liquid level control means. Accordingly, by inserting the band-shaped current collector into the container through the current collector insertion hole of the container and passing through the slit of the filling amount adjusting member, the paste is uniformly applied to the band-shaped current collector. Can be filled. Moreover, since a filling process can be continued over a long period of time, the working efficiency of the filling process can be improved.
[0012]
【Example】
Embodiment First, a paste filling apparatus used in an embodiment of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a perspective view of an essential part of a paste filling apparatus according to the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.
The long box-shaped frame-shaped main body 1 is formed with top plates 1a and (1b) at both upper ends perpendicular to the longitudinal direction (1b is not shown). The main body 1 has an opening 2 between the top plates 1a and (1b). Two bottom plates (not shown) are formed at both ends of the lower portion orthogonal to the longitudinal direction of the main body 1. Rollers (not shown) are disposed in the main body 1 and both ends thereof are fixed to the bottom plate.
[0014]
The first portal bracket 3 is fixed to the top plate 1 a of the main body 1. The bracket 3 has a rectangular cutout on the upper surface located on the opening 2 side of the main body 1. The bracket 3 has two support pins 4a and 4b arranged on the upper surface in parallel with a desired distance from each other. The two columns 5a and 5b are fixed to the top plate 1a located between the columns of the bracket 3 at equal intervals. A second portal bracket (not shown) having the same structure as that of the bracket 3 is arranged on the top plate (1b) of the main body 1 so as to face the bracket 3 with the opening 2 interposed therebetween. ing. Further, on the top plate 1b located between the columns of the second portal bracket, two columns (not shown) having the same structure as the columns 5a and 5b are provided with the columns 5a and 5b and the opening. It arrange | positions so that the part 2 may be pinched | interposed.
[0015]
The rectangular paste containing container 6 has a rectangular flange 6 a at the upper opening, and a long hole 6 b serving as a current collector insertion hole is opened at the center of the bottom surface along the longitudinal direction of the container 6. The upper ends of the support columns 5a and 5b are attached to the lower surface of the flange portion 6a (front side) orthogonal to the longitudinal direction of the container 6, respectively. Further, the upper ends of the two struts on the top plate (1b) are fixed to the lower surface of the flange (not shown) opposed to the flange 6a across the upper opening of the container 6. One end of each of the two paste introduction pipes 7a and 7b is connected to the side surface of the container 6, and the other end thereof extends upward. The introduction tube 7a is ₁ three paste introducing hole 8 which is arranged at equal intervals from each other on the side walls, _82, has a (8 ₃₎ (8 ₃ are not shown). The introduction pipe 7b has three paste introduction holes (8 ₄ ), 8 ₅ , (8 ₆ ) (8 ₄ , 8 ₆ are not shown) arranged on the side wall at equal intervals. A diaphragm pump (not shown) serving as a paste supply means is connected to each of the introduction holes 8 ₁ to 8 ₆ .
[0016]
Two prismatic upper coolers 9a and 9b are respectively interposed between the upper side surface of the container 6 and the introduction pipes 7a and 7b. The two lower coolers 10a and 10b are each formed from a prism having a rising portion at an end along the longitudinal direction. The main body of each of the lower coolers 10 a and 10 b is fixed to the bottom of the container 6 so that the rising portion covers the center of the lower side surface of the container 6. These coolers 9a, 9b, 10a, and 10b are configured so that cooling water circulates therein, and thereby the temperature of the paste stored in the container 6 is maintained at 10 ° C to 15 ° C. . The two paste stoppers 11a and 11b are each made of a rubber prism, and are attached to the bottom of the container 6 so as to sandwich the elongated hole 6b.
[0017]
The holding means 12 for holding the paste filling amount adjusting member is composed of a rectangular frame 13 and two rectangular pieces having protrusions at the lower portion fixed to the lower surface of the frame 13 along the longitudinal direction at a desired distance from each other. Holding plates 14a and 14b. The two holding plates 14 a and 14 b of the holding means 12 are arranged in the container 6. A frame 13 (front side) orthogonal to the longitudinal direction of the holding means 12 is placed on the upper surface of the bracket 3. The support pins 4a and 4b are penetrated through the frame 13, respectively. The front side frame 13 orthogonal to the longitudinal direction is fixed on the bracket 3 by screwing the upper ends of the support pins 4a and 4b. The front frame 13 orthogonal to the longitudinal direction and a frame (not shown) facing each other across the opening of the frame 13 are placed on the second portal bracket. This frame is also fixed on the second portal bracket by a support pin. The paste filling amount adjusting member 15 has a rectangular slit 16a at the top and a long hole 16b formed so as to communicate with the slit. The long hole 16b has an inner surface that is expanded outward. The filling amount adjusting member 15 is placed on the protrusions of the two holding plates 14a and 14b. Five centering guides 17 ₁ , 17 ₂ , (17 ₃ ), (17 ₄ ), (17 ₅ ) (17 ₃ , 17 ₄ , and 17 ₅ are not shown) are equally spaced on the paste filling amount adjusting member 16. Are arranged at a distance of.
[0018]
Two large-sized L-shaped substrate presser bar fixing plates 18 ₁ , (18 ₂ ) (18 ₂ not shown) are respectively attached to both ends of the holding plate 14 a so as to face each other. Two small L-shaped substrate presser holding plates 19 ₁ , (19 ₂ ) (19 ₂ is not shown) are respectively attached to both ends of the holding plate 14 b so as to face each other. Both ends of the upper substrate presser bar 20 are fixed to the two fixing plates 18 ₁ and (18 ₂ ), respectively. The lower substrate presser bar 21 is disposed below the presser bar 20, and both ends thereof are fixed to the _two fixing plates 18 ₁ and (18 ₂ ), respectively. Both ends of the central substrate presser bar 22 are fixed to the two fixing plates 19 ₁ and (19 ₂ ), respectively.
[0019]
The paste liquid level control means includes two long box floats 23a and 23b. The two floats 23a and 23b are arranged so as to sandwich the two holding plates 14a and 14b in the container 6. Each of the floats 23a and 23b has two float support pins 24 ₁ , (24 ₂ ), 24 ₃ , (24 ₄ ) (24 ₂ and 24 ₄ are not shown). The upper portions of the float support pins 24 _{1 to} 24 ₄ protrude from the frame 13. Four cylindrical stoppers 25 ₁ , (25 ₂ ), 25 ₃ , (25 ₄ ) (25 ₂ , 25 ₄ are not shown) are connected to the four float support pins 24 ₁ , (24 ₂ ), 24 _3. , (24 ₄ ), respectively. A transmissive photoelectric sensor (not shown) for determining the paste liquid level in contact with the inner surface of the container 6 is attached to the frame 13 along the longitudinal direction. The sensor has a function of detecting that the cylindrical stoppers 25 _{1 to} 25 ₄ have passed through the position where the sensor is attached. The position of the sensor is set to a height at which the cylindrical stoppers 25 _{1 to} 25 ₄ are lowered when the paste liquid level (H ₁ ) in contact with the inner surface of the container 6 is lower than the target height. Yes. The sensor is attached with a controller (not shown) configured to drive the diaphragm pump while a detection signal from the sensor is input. In such a paste liquid level control means, when the amount of paste stored in the container 6 decreases, the paste liquid level H _{1 in} contact with the inner surface of the container 6 decreases and the two floats 23a and 23b together with the respective floats 23a and 23b. The cylindrical stoppers 25 _{1 to} 25 ₄ are lowered. When each of the stoppers 25 _{1 to} 25 ₄ is detected by the sensor, a detection signal is input to the controller, and the diaphragm pump is driven to supply paste into the container 6 from the two introduction pipes 7a and 7b. Is done. When the paste liquid level H ₁ in contact with the inner surface of the container 6 reaches a target height, the stoppers 25 _{1 to} 25 ₄ rise together with the two floats 23a and 23b, and these stoppers are detected by the sensor. Therefore, the controller stops driving the diaphragm pump, and the supply of the paste is stopped. As a result, the paste liquid level H _{1 in} contact with the inner surface of the container 6 is maintained at a target height.
[0020]
Hereinafter, the manufacturing method of the paste type electrode of this invention is demonstrated using the paste filling apparatus mentioned above.
First, carbon as a conductive material, carboxymethyl cellulose, sodium polyacrylate dispersion, polytetrafluoroethylene dispersion as water, and water are added to a hydrogen storage alloy and kneaded to prepare a paste. did. The paste was aged by standing in a low-temperature chamber at 10 ° C.
[0021]
Then, the paste is supplied from the two paste introduction pipes 7a and 7b into the container 6 by the diaphragm pump as the paste supply means, and the paste liquid is in contact with the inner surface of the container 6 as shown in FIG. The surface H ₁ was supplied so as to have a desired height (H ₃ ) higher than the paste liquid surface (H ₂ ) in the slit 16 a of the filling amount adjusting member 15. As a result, since the pressure of the paste in the container 6 was increased almost uniformly, no shear stress was applied to the paste.
[0022]
Next, by rotating the roller, a band-shaped punched metal S (having a thickness of 80 μm) as a current collector is inserted into the container through the long hole 6a of the container 6, and the substrate presser bar 20 , 21 and the substrate presser bar 22 are passed through the slot 16b, the slit 16a, and the centering guides 17 _{1 to} 17 ₅ of the filling amount adjusting member 15 so that the paste is uniformly applied to the band-shaped punched metal S. Filled. When the paste liquid level H _{1 in} contact with the inner surface of the container 6 decreases with this filling, a detection signal is input from the sensor of the paste liquid level control means to the controller, and the paste is transferred from the diaphragm pump to the container 6. Supplied. Accordingly, during the filling process, the difference between the paste liquid level H _{1 in} contact with the inner surface of the container 6 and the paste liquid level H ₂ in the slit 16a of the filling amount adjusting member 15 is kept constant (H ₃ ). The pressure applied to the paste in 6 was kept constant. In this way, the pressure of the entire paste in the container 6 is increased almost uniformly and the pressure is maintained constant, and the band-like punched metal S is moved from the elongated hole 6b of the container 6 into the container 6. The paste was uniformly filled in the strip-shaped punched metal S200m by being inserted into the slit 16a and passing through the slit 16a.
[0023]
This paste-filled strip-shaped punched metal E was dried and then pressed to prepare a negative electrode.
Comparative Example Using the paste filling apparatus shown in FIG. 4 described above, the same paste as in the example was placed in the container 31, the roller 35a was rotated counterclockwise, and the roller 35b was rotated clockwise. When a belt-like punched metal similar to that of the embodiment is inserted into the container 31 through the long hole 31a and moved upward, the roller 35a, 35b causes the paste to move around the punched metal. Metal was filled with the paste. By passing this punched metal through the tapered elongated hole 34 and the slit 33 of the paste filling amount adjusting member 32, the excess paste was removed and the filling amount was adjusted. After drying this, the negative electrode was produced by pressing.
[0024]
The obtained negative electrodes of Examples and Comparative Examples were punched into a disc having a diameter of 30 mm every 10 m, the weight of the disc was measured, and the result is shown in FIG.
As is clear from FIG. 3, the belt-shaped current collector is inserted by inserting the strip-shaped current collector into the container through the current collector insertion hole while applying a constant pressure to the paste and passing through the slit of the filling amount adjusting member. It turns out that the negative electrode of the Example which fills a body with a paste is constant over a long period of time. On the other hand, the negative electrode of the comparative example in which the paste is filled in the current collector by bringing the paste around the belt-shaped current collector with a roller and locally increasing the pressure of the paste, as the filling process proceeds It can be seen that the weight decreases.
[0025]
【The invention's effect】
As described in detail above, according to the paste electrode manufacturing method of the present invention, the paste can be uniformly filled into the strip-shaped current collector, the yield can be improved, and the working efficiency of the filling process can be improved. There is a remarkable effect that it can be done.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a paste filling apparatus according to the present invention.
2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a characteristic diagram showing the change over time in the weight of the negative electrode in an example of the present invention.
FIG. 4 is a cross-sectional view showing a manufacturing process of a conventional paste electrode.
[Explanation of symbols]
6 ... Paste container, 6b ... Long hole, 7a, 7b ... Paste introduction pipe, 12 ... Holding means, 15 ... Paste filling amount adjusting member, 16a ... Slit, 23a, 23b ... Float, 24 _{1 to} 24 ₄ ... Float support Pin, 25 _{1 to} 25 ₄ ... stopper.

Claims (2)

In a paste filling apparatus in which a paste containing an active material and polytetrafluoroethylene is used,
A paste container having a current collector insertion hole on the bottom surface;
Paste supply means for supplying the paste into the container;
Two holding plates disposed at a distance from each other in the container;
A paste filling amount adjusting member having a slit that is disposed between the two holding plates and through which the band-shaped current collector inserted from the current collector insertion hole passes;
Paste liquid surface for making the paste liquid surface between the inner surface of the container and each holding plate higher than the paste liquid surface in the slit filled with the paste and keeping the difference between the liquid surfaces constant With height control means
A paste filling apparatus comprising: 2. The paste filling apparatus according to claim 1, wherein the paste liquid level control means includes a sensor for detecting that the paste liquid level between the inner surface of the container and each holding plate is lowered.

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