JP2578649B2 - Method and apparatus for manufacturing battery electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention relates to a method for producing a battery electrode using a porous metal body having three-dimensional communication holes as a base, which is used for an alkaline storage battery and the like, and its production method. It concerns the device.

(B) Conventional technology As a method of manufacturing an electrode used in a sealed alkaline storage battery or the like, in recent years, instead of a sintering method, an active material powder has been filled in a porous metal body having three-dimensional communication holes. Non-sintering processes have been studied. This manufacturing method is regarded as an effective manufacturing method for cost reduction and performance improvement because the manufacturing process can be simplified, the manufacturing time can be shortened, and the energy density of the electrode can be easily increased.

This typical manufacturing method is specifically based on the following steps. Felt-like crystal of nickel fiber (hereinafter referred to as nickel matte, fiber diameter 20 μm, average pore diameter 50)
μm, having a physical property of porosity of 93%) as a substrate, and then filling a slurry prepared by mixing an active material powder mainly composed of nickel hydroxide powder having an average particle diameter of 20 μm with a paste liquid. After drying, compression is performed to obtain a completed electrode.

By the way, since this nickel matte was originally developed as a filter, when the active material slurry was filled, only the liquid entered the inside, the active material powder was passed over the nickel matte surface, and the required amount of the active material was Disadvantageously cannot be filled. In order to improve this disadvantage, Japanese Patent Publication Nos. 59-31832, 59-24492 and 56
-37665, JP-A-59-81868, JP-A-59-143270
And other proposals. The former three are intended to mechanically rub the slurry supplied by the rubbing tool on the upper surface of the substrate, but have the problems that the configuration of the apparatus is complicated and that the filling amount is difficult to equalize. There is. In the latter two, the slurry is sprayed onto the substrate together with air to fill the substrate with the pressure. However, since high pressure is used, the substrate cannot be used unless the substrate is sufficiently rigid. In addition, since air is filled together, the amount of filling is small, and it is difficult to obtain quantitative properties.

(C) Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned problems, and fills a slurry-like active material vertebra into a base made of a porous metal body having three-dimensional communication holes. In this regard, the present invention proposes a battery electrode manufacturing method and a device for providing a battery electrode having excellent various characteristics by efficiently filling the electrode at a high filling rate and uniformly in the electrode manufacturing process.

(D) Means for Solving the Problems The method for producing a battery electrode of the present invention is based on a method in which a porous metal body having three-dimensionally continuous pores is used as a base, and the pores of the base are continuously supplied. A method of filling a slurry containing the active material powder as a main component, a tank filled with the slurry, and a roller is installed at a position at least partially immersed in the slurry of the tank but not completely immersed, Guiding the substrate so as to be in contact with at least one point not submerged in the slurry of the roller, rotating the roller so as to have a sufficiently high relative speed to the moving substrate, and filling the substrate with the slurry. It is characterized by the following.
Further, the slurry used in the present invention is preferably a viscous fluid exhibiting Newtonian flow, the viscosity of which is 1000
~ 10000cp is suitable. Further, the relative speed of the roller surface to the substrate is preferably at least three times the moving speed of the substrate.

On the other hand, the apparatus for manufacturing a battery electrode according to the present invention is based on a porous metal body having three-dimensionally continuous pores as a base, and mainly containing an active material powder in pores of the base which are continuously supplied. An apparatus for filling a slurry, a means for continuously supplying the substrate, a tank filled with the slurry, a filling roller for filling the substrate with the slurry, and removing unnecessary adhered slurry from the substrate. A scraper and a driving device for rotating the filling roller, wherein the filling roller is disposed at a position where it is at least partially immersed in the slurry of the tank but is not completely immersed, and is immersed in the slurry of the tank. The driving device rotates the filling roller so as to have a sufficiently high relative speed to the moving substrate. It is intended to. Here, the relative speed of the surface of the filling roller with respect to the substrate is preferably at least three times the moving speed of the substrate. In addition, it is preferable to form a plurality of grooves dug at right angles to the rotation direction on the outer peripheral surface of the filling roller.

(E) Action The present inventors made various active materials containing a nickel hydroxide powder in a slurry form as a main component, and examined filling properties of the active material. As a result, the excess on the surface of the substrate was found to be greatly improved by adjusting the slurry so as to exhibit a Newtonian flow by adding an appropriate amount of paste liquid to the slurry. This is considered to be because the affinity between the liquid and the powder is improved and separation becomes difficult, and the fluidity enough to sufficiently resist the resistance that hinders the flow of the substrate surface is maintained.

However, even if such a slurry is used, the excess property cannot be completely prevented, and a cake-like slurry having a small but low moisture content is formed on the surface of the substrate which is simply dipped in the slurry. It was found that pores that adhered and that were not filled with slurry remained inside the substrate. And adhesion of a low water content cake slurry,
In order to prevent the remaining of unfilled vacancies, it is important to efficiently carry out the auxiliary filling operation so as not to cause the liquid-powder separation and to efficiently exchange the air inside the substrate with the slurry. This has been clarified by the study by the present inventors. An experiment was conducted on a method capable of clearing these two points. A roller was placed at a position where it was at least partially immersed in the slurry but was not completely immersed, and the substrate was contacted at at least one point not immersed in the slurry of the roller. It has been found that it is optimal to rotate the rollers with a sufficiently high relative speed to the moving substrate and to fill the substrate with the slurry.

Then, the apparatus shown in FIGS. 1A and 1B was developed, and the present invention was completed.

1 (a) and 1 (b) show an embodiment of a device for manufacturing a battery electrode according to the present invention. In FIG.
Reference numeral 2 denotes a slurry, 3 denotes a scraper for scraping off excess slurry adhering to the substrate surface, 4 denotes a reversing roller, 5 denotes a filling roller, 6 denotes a substrate, 7 denotes a guide roller, and 9 denotes a driving roller. Here, the base 6 is a driving roller 9
Is pulled in the direction of the arrow, and is continuously supplied and driven. The diameter of the driving roller 9 and the filling roller 5
Is substantially equal in this embodiment. As a result, the rotation speed of the filling roller 5 is set to, for example, four times the rotation speed of the driving roller 9, and the filling roller 5 is rotated in the same direction as the moving direction of the base (see FIG. 1A). The relative speed of the roller surface to the substrate is
The moving speed of the substrate can be set three times.

On the other hand, when the filling roller 5 is rotated in a direction opposite to the moving direction of the substrate (see FIG. 1B), and the rotation speed of the filling roller 5 is twice the rotation speed of the driving roller 9, the surface of the filling roller 5 is Of the substrate corresponds to three times the moving speed of the substrate.

The substrate, such as nickel matte, which is continuously supplied, is guided via guide rollers onto the filling roller (8) not immersed in the slurry. The filling roller 5 is installed so that at least a part thereof is immersed in a sufficient amount of slurry, and is rotated by a driving device (not shown) at a set speed in the same direction as the moving direction of the substrate. It is configured. Due to this rotation, the slurry adheres in a film form on the roller surface above the liquid surface, and at the contact point 8 with the substrate.
And filled into the substrate. Here, the slurry has its own fluidity, the moving speed of the base, and the sliding action obtained by changing the peripheral speed of the roller,
The substrate is filled without changing the water content. Also,
This filling method is carried out from the point at which the substrate comes into contact with the filling roller surface to the point at which it is separated from the roller surface and submerged in the slurry pond. Therefore, since the slurry to be filled is always supplied from below and pushed upward, the replacement with the air in the substrate can be performed smoothly, and a uniform filling state can be obtained without leaving holes.

By the way, when the above-mentioned filling method is adopted, it has been found that the filling state changes depending on the relationship between the sliding speed of the filling roller and the moving speed of the substrate. Then, the present inventors measured the change of the filling amount and the variation when the relative speed of both was changed. FIG. 2 and FIG. 3 show the results.

FIG. 2 is a graph showing the relationship between the moving speed of the substrate and the rotational speed of the filling roller (the direction of the arrow α in FIG. 1A) as shown in FIG. 1 (a). It is a figure which shows the relationship between the relative speed (V, S, base | substrate) of the filling roller surface, and active material filling amount. It is understood that when the peripheral speed of the filling roller is about four times the moving speed of the substrate, that is, when the relative speed of the surface of the filling roller to the substrate is about three times the moving speed of the substrate, almost uniform and high-density filling can be performed. . The dashed line drawn in the figure is the theoretical maximum filling amount obtained from the density of the slurry used for the test. The base used for the test was nickel matte having an average pore diameter of 50 μm, a fiber diameter of 20 μm, and a porosity of 93%. The slurry was prepared by mixing nickel hydroxide powder having an average particle diameter of 20 μm with an aqueous solution of methylcellulose (MC), and using a B-type viscometer. 3000 in measurement
It shows Newtonian flow prepared to be cp.

In FIG. 2, in all cases where the ratio of the relative speed of the surface of the filling roller to the substrate and the speed of the movement of the substrate were small and the amount of filling was small, clogging occurred near the substrate surface, and an excessive phenomenon was observed. .

FIG. 3 is a view showing the filling roller with respect to the substrate when the moving direction of the substrate and the rotation direction of the filling roller (the direction of arrow β in FIG. 1B) are opposite to each other, as shown in FIG. 1 (b). It is a figure which shows the relationship between the relative speed (V, S, base | substrate) of a surface, and active material filling amount. The horizontal axis in FIG. 3 indicates the absolute value of the peripheral speed of the filling roller without considering the directionality. It can be understood that even when the rotation direction of the filling roller is different, if the relative speed of the surface of the filling roller to the substrate is about three times the moving speed of the substrate, almost uniform and high-density filling can also be performed. The dashed line drawn in the figure is the theoretical maximum filling amount obtained from the density of the slurry used in the test. The conditions here were the same as in the above test.

Next, an experiment was conducted on the effect of the change in viscosity of the slurry on the filling property. Table 1 shows the results at this time. From this, if the slurry shows Newtonian flow, the viscosity is 1000
It is understood that filling can be performed without any problem in the range of ~ 10000cp. In addition, it was confirmed in experiments that the low-viscosity slurry tends to easily obtain a good filling state even when the relative speed of the surface of the filling roller to the substrate becomes small. And, when the viscosity is less than 1000 cp, sedimentation of the powder occurs quickly, it is difficult to maintain a uniform slurry, and the water content increases, the active material density in the slurry decreases, and the filling amount decreases.
Such defects as appear. On the other hand, when it exceeded 10,000 cp, the phenomenon that the fluidity of the slurry was low and did not flow into the inside of the substrate occurred. The slurry used here was
All show Newtonian flow. The flow direction of the substrate and the rotation direction of the filling roller are set to be the same direction, and the relative speed of the surface of the filling roller to the substrate is set to be six times the moving speed of the substrate. And the filling amount unit (g / cc-
void) indicates the weight of the active material filled per unit volume of the real space in the substrate.

(F) Examples Hereinafter, the present invention will be described in detail with reference to comparison between examples of the present invention and comparative examples.

(Example 1) A nickel hydroxide powder as an active material and an aqueous MC solution were mixed to prepare a slurry exhibiting a Newtonian flow of 3000 cp in viscosity. The nickel matte having a fiber diameter of 20 µm, an average pore diameter of 50 µm, and a porosity of 93% was prepared. 1 Using a filling device as shown in FIG. 1A, the moving direction of the substrate and the rotation direction of the filling roller are set to the same direction, and the relative speed of the surface of the filling roller to the substrate is
The slurry was filled so as to be four times as fast as the moving speed of the substrate.

(Example 2) Using the same slurry, substrate, and filling device shown in Fig. 1 (b) as in Example 1, the moving direction of the substrate and the rotation direction of the filling roller were set to be opposite directions, and the surface of the filling roller against the substrate was used. The filling roller was rotated so that the relative speed was 6 times the moving speed of the substrate, and the slurry was filled.

(Example 3) Using the same slurry, substrate, and filling device as in Example 1, using a filling roller provided with a number of tanks cut on the outer peripheral surface in a direction perpendicular to the rotation, and otherwise using the same conditions as in Example 1. The slurry was filled.

(Comparative Example 1) The amount of paste in the MC aqueous solution to be added was reduced, and a slurry having the same water content but not showing Newtonian flow was used.

(Comparative Example 2) A slurry was filled in the same manner as in Example 1 except that the relative speed of the surface of the filling roller to the substrate was set to be twice the moving speed of the substrate.

(Comparative Example 3) Example 1 using a sliding tool that reciprocates on the upper surface of the substrate.
Filling was performed while continuously supplying the same slurry as above on the same substrate.

The weight of the filled substrate shown in the examples was measured after drying, and the actual amount of the filled substrate was determined. Table 2 shows the results.

It can be seen that the electrode according to the present invention is excellent in any of the filling level, uniformity and productivity. It is also understood that the influence of the rotation direction of the filling roller is small. Then, as shown in Example 3, it was found that the filling efficiency was further increased by forming a groove on the surface of the filling roller. It is considered that this is because the contact angle at the contact point between the base and the filling roller increases, and the press-in force increases.

In addition to the factors described above that vary the filling amount of the slurry, the length of the distance in which the substrate moves while being in contact with the roller surface after contacting the filling roller, that is, the contact area between the substrate and the roller is practical. Since most of the filling was performed at the contact points, no significant difference appeared even if this was changed.

In the embodiment, the electrode using nickel hydroxide as a main active material has been exemplified. However, the present invention is not limited to this, and an oxide layer may be used. Also, nickel matte is used as the metal porous body having three-dimensional communication holes, but it goes without saying that foam nickel or the like can be used.

(G) Effect of the Invention According to the method and apparatus for manufacturing a battery electrode of the present invention, it is possible to efficiently and efficiently fill a substrate with an active material at a high filling rate in an electrode manufacturing process. The industrial value is extremely large.

[Brief description of the drawings]

1 (a) and 1 (b) show one embodiment of the apparatus for manufacturing a battery electrode according to the present invention, and FIG. 1 (a) shows the moving direction of the base and the rotating direction of the filling roller. 1 (b) shows an example in which the direction of movement of the substrate and the direction of rotation of the filling roller are opposite to each other, and FIGS. 2 and 3 both show movement of the substrate. FIG. 2 is a diagram showing the relationship between the relative speed (V, S, substrate) of the filling roller surface and the amount of filling with respect to the speed, and FIG. 2 shows the relationship when the moving direction of the substrate and the rotating direction of the filling roller are set to the same direction. FIG. 3 is a view showing the relationship when the moving direction of the base and the rotating direction of the filling roller are set to opposite directions. 1 ... tank, 2 ... slurry, 3 ... scraper, 4 ...
Reversing roller, 5 ... Filling roller, 6 ... Base, 7 ...
... guide roller, 8 ... contact point between filling roller and substrate, 9 ... drive roller.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahito Tomita 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Haraguchi 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Yo Electric Co., Ltd.

Claims (7)

(57) [Claims] 1. A method of filling a slurry containing an active material powder as a main component into pores of a continuously supplied substrate having a porous metal body having three-dimensionally continuous pores as a substrate. A tank filled with the slurry, a roller is installed at a position at least partially immersed in the slurry of the tank but not completely immersed, and contacted at at least one point not immersed in the slurry of the roller. A method for manufacturing an electrode for a battery, comprising: guiding the substrate, rotating the roller so as to have a sufficiently high relative speed to the substrate to be moved, and filling the substrate with the slurry. 2. The method according to claim 1, wherein the slurry is a viscous fluid exhibiting Newtonian flow. 3. The method for manufacturing an electrode for a battery according to claim 1, wherein a relative speed of the roller surface to the substrate is at least three times a moving speed of the substrate. 4. The method according to claim 1, wherein the slurry has a viscosity of 1,000 to 10,000 cp. 5. An apparatus in which a porous metal body having three-dimensionally continuous pores is used as a base, and a slurry containing an active material powder as a main component is filled in the continuously supplied pores of the base. A means for continuously supplying the substrate, a tank filled with the slurry, a filling roller for filling the slurry with the substrate, a scraper for removing unnecessary adhered slurry from the substrate, and rotating the filling roller. A driving device for driving, wherein the filling roller is disposed at a position where it is at least partially immersed in the slurry of the tank but is not completely immersed, and at least one point not immersed in the slurry of the tank. Wherein the driving device rotates the filling roller so as to have a sufficiently high relative speed with respect to the substrate to be moved. 6. The apparatus for manufacturing a battery electrode according to claim 1, wherein a relative speed of the surface of the filling roller to the substrate is at least three times a moving speed of the substrate. 7. An apparatus for manufacturing an electrode for a battery according to claim 1, wherein said filling roller has a plurality of grooves dug at right angles to a rotation direction on an outer peripheral surface.