JPH09129242A - Metallic porous body, manufacture thereof, and electrode for battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good metal porous body with almost no difference in directional property by specifying the ratio of length and breadth of a pore of resin by applying permanent strain to foamed resin before plating when the metal porous body is manufactured by plating the foamed resin. SOLUTION: Before plating of foamed resin (foamed urethane or the like), conical rollers 3, 4 are pushed at the specified angle against an elastic foamed resin sheet 2 coiled around a roll 1, rotated in accordance with the running direction of the sheet 2 to spread the sheet 2 in the width direction by the difference in diameters of the rollers 3, 4. The angle, diameter ratio, pushing force against the sheet 2 of the rollers 3, 4 are adjusted based on the material, breadth of the sheet 2, and the ratio of length and breadth of the pore diameter of the sheet 2 is controlled to 1.2 or less by the remaining permanent strain. The directional property of a metal porous body is decreased so as to have almost the same tensile strength in any direction, and a storage battery with stable quality can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a battery electrode used in a secondary battery such as a nickel-cadmium battery or a nickel-hydrogen battery.

[0002]

2. Description of the Related Art Already used as secondary battery electrodes are metal foams made of urethane foam plated with Ni, and metal nonwoven fabrics made of non-woven fabric plated with Ni. Particularly, when urethane foam is used as the plating base, the prepared metal porous body has the pores of the foamed resin as the base extending in a certain direction, as described in JP-B-58-34902. The metal porous body formed by plating has a directional tensile strength. As a result, the winding direction is specified when using the battery electrode. Further, Japanese Patent Application Laid-Open No. 3-226969 describes that, at the time of foaming resin serving as a base, the foaming direction of the resin is found and the sheet is peeled in the same direction. In both cases, the foamed resin is cut out and used.

[0003]

The distortion of the pores of the foamed resin does not pose a particular problem as long as the method utilizing directionality as in Japanese Patent Publication No. 58-34902 is used. It is necessary to confirm the orientation of the foam, and a design that cuts out from a sheet is required. Further, in JP-A-3-226969, only the foaming direction of the foamed resin as the base is determined, and the metal foamed body formed therefrom is also used after finding the directionality. Such troublesomeness has a different tensile strength depending on the direction of the porous metal body, and therefore, when the sheet-shaped metal foam is wound and when the foam is filled with an active material, a tensile force is exerted on the sheet. It is caused by the fact that it works and causes problems such as cutting of metal mesh. In addition, due to the length-to-width ratio of the pores, the movement of electrons in the active material in the major axis direction is significantly deteriorated, causing problems such as deterioration of battery discharge capacity.

The present invention alleviates the directionality of such a metal foam and enables it to be used without worrying about the directionality of the sheet-shaped metal foam.

[0005]

The present invention is characterized in that, in a metal porous body formed by plating a foamed resin, the length-width ratio of the pores of the metal porous body is 1.2 or less. The present invention provides a metal porous body, which is manufactured by applying a permanent strain to a foamed resin before plating to adjust the length-to-width ratio of pores of the resin to 1 to 1.2 or less. It is characterized in that plating is applied after the foam. Further, it is preferable that the means for applying a permanent strain to the foamed resin uses a conical roller.

Then, the porous metal body is used as a substrate, which is filled with an active material and then used as a battery electrode which is used as a layer with a separator and a counter electrode.

[0007]

[Function] The direction of the foamed resin is the same as in the prior art described above.
Some are considered at the stage of forming foamed resin sheets,
As a matter of fact, when the sheet of the foamed resin is wound on a roll and when the roll is used as a material for plating, the elongation in the longitudinal direction of the sheet due to the tension increases the length-width ratio of the pores of the foamed resin. When plated in that state, it is fixed as it is while maintaining the vertical-horizontal length ratio of the pores. In the direction in which the length of the pores is long, the strength of the pores is weakened because the bending force is increased and the distance between the fulcrums is increased.

According to the present invention, in order to mitigate such deformation due to tension, a foamed resin sheet supplied as a pre-process of the plating process or as a raw material is pressed by a conical roller before plating, The sheet is stretched in the direction perpendicular to the running direction, and the residual strain thereof relaxes the deformation in the running direction. FIG. 1 presents, as an example thereof, means for using a widening roller. In this case, when the conical rollers 3 and 4 are pressed against the elastic sheet 2 wound around the roll 1 at a certain angle and rotated in accordance with the traveling direction of the sheet, the width of the sheet is widened due to the difference in the diameter of the roller. Can be spread in any direction. Since the sheet has elasticity, it contracts from the once widened width, but a permanent strain remains and the sheet is supplied to the plating step in the widened state. It is possible to change the shape of the roller, but it is better to load the sheet along the surface of the sheet, and it is best to add extra stress in the direction perpendicular to the surface of the sheet to the flatness of the surface during plating in the subsequent process. Influential and not appropriate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION By observing the metal foam plated in this way, the length and width of the pore diameter can be adjusted, and the angle of the roller, the diameter ratio of the conical roller, and the pressing force to the sheet can be adjusted. By doing so, the ratio of the pore length to the length to width can be 1.2 or less.

This operation needs to be adjusted depending on the material, width and thickness of the sheet to be supplied, the diameter of the pores, etc., and also the strength of the tension applied to the sheet during the plating operation. , The dimensions of the rollers used cannot be determined uniformly.

Since the aspect ratio of the pores is 1.2 or less, the characteristics of the finished metal porous body are that the metal porous body has substantially the same hardness when pulled or bent from any direction. When used as a battery electrode, this porous metal body can be cut into a predetermined size and used without confirming the orientation of the sheet. Further, as described above, the movement of the electrons in the active material in the pores becomes uniform in the vertical and horizontal directions, so that the battery discharge capacity can be expected to be improved.

[0012]

【Example】

Example 1 A urethane foam sheet having a width of 1 m, a length of 50 m and a thickness of 1.7 mm is supplied by rolling. The pores of this urethane foam had a length / width direction ratio of 1.2. A total of four conical rollers 3 and 4 having a length of 500 mm, a root diameter of 200 mm, and a tip diameter of 100 mm are set between the roll winding 1 and the plating tank entrance as shown in FIG. Send out the sheet at a constant speed, adjust the distance between the tips of the rollers facing each other, and the number of rotations of the roller, and set the width to 1
It was decided that the m-sized sheet would expand to an average width of 1.1 m. At this time, the ratio of pore length direction / width direction is 1.05.
Met.

After that, Ni plating was performed by electroless plating and electroplating, and then 370 g /
An m ² Ni metal foam was obtained. Here, the length direction of the pores /
When the ratio in the width direction was measured, it was 1.15.

Samples for tensile test were taken out in the width direction and the length direction of this foam, and each n = 20 test was conducted.
Table 1 shows the results.

Further, this foam is 37 mm wide and 90 mm long.
Cut into 10 mm sheets each in the direction perpendicular to the longitudinal direction of the sheet, each of which is filled with a cadmium battery active material, and then pressed to a thickness of 0.8 mm to obtain a positive electrode, and a negative electrode with cadmium and nylon between them. A separator was laminated and wound, and potassium hydroxide was used as an electrolytic solution to obtain a cadmium storage battery. 80 minutes after charging this battery at 80mA for 15 hours
The discharge capacity was examined by discharging to 1.0 V at 0 mA. Table 2 shows the results.

Comparative Example 1 Using a foamed urethane sheet of the same lot as in Example 1 and omitting the use of a conical roller, a metal foam, a sample and a cadmium storage battery were prepared and evaluated under the same conditions as in Example 1. The tensile strength is shown in Table 1 and the discharge capacity is shown in Table 2.

The aspect ratio of the pores was 1.2 in the state of urethane foam, but changed to 1.4 after plating.

Example 2 A urethane foam having the same size as in Example 1 and having a large aspect ratio of pore diameter was prepared. The ratio of the length direction / width direction of the pores of the sheet was 1.3. This sheet was adjusted to have a ratio of 1.08 using a conical roller as in Example 1, and then Ni-plated to obtain a metal foam. At this time, the ratio of pore length direction / width direction was 1.17. The foam was sampled and tensile tested as in the examples. Table 1 shows the results.

20 mm × 30 m from this foam sheet
A sample was cut into a size of m, coated with nickel hydroxide, and then compressed to 0.63 mm by a roll press. Prepare the sample by changing the sheet collection direction and roll press direction, and
The presence or absence of fracture of the skeleton was observed by EM. Table 3 shows the results.

Comparative Example 2 The same urethane foam as in Example 2 was Ni-plated without using a conical roller. The ratio of the length direction / width direction of the pores of the finished metal foam was 1.4. The sample was cut out, roll-pressed and observed in the same manner as in Example 2.

The results are also shown in Table 3.

[Table 1]

[Table 2]

[Table 3]

As described above, the porous metal body of the present invention is
There is no great difference in directionality, and a good porous metal body can be obtained regardless of the situation of the material of the foamed resin. Further, the storage battery manufactured using the porous metal body of the present invention can secure stable quality.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an example of means for giving a permanent strain to a foamed resin in the present invention.

[Explanation of symbols]

 1 ... Roll of foamed resin sheet, 2 ... Foamed resin sheet 3, 4 ... Conical roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuichi Yoshikawa 2 at 10 E, Nago, Shinminato City, Toyama Prefecture Toyama Sumitomo Electric Co., Ltd.

Claims (4)

[Claims] 1. A porous metal body obtained by plating a foamed resin, wherein the length / width ratio of pores of the porous metal body is 1.2 or less. 2. A method for producing a metal porous body having a foamed resin as a plating substrate, wherein a permanent strain is applied to the foamed resin before plating so that the length-width ratio of pores of the resin is 1: 1.2. A method for producing a metal porous body, which comprises subjecting a foamed body prepared below to plating. 3. A means for applying a permanent strain to the foamed resin,
The method for producing a metal porous body according to claim 2, wherein a conical roller is used. 4. An electrode for a battery, which comprises the porous metal body as a base material, and after filling the active material therein with a separator and a counter electrode in layers.