JPH065618B2 - Method for producing paste type cadmium cathode plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a paste type cadmium cathode plate in which the active material is prevented from falling off, the high rate discharge characteristics are excellent, and the oxygen gas absorption performance is significantly improved. It relates to a manufacturing method.

(B) Prior art Conventionally, a paste type cadmium cathode plate used for an alkaline storage battery such as a nickel-cadmium battery has been disclosed in Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 8-80265, metal cadmium corresponding to a part of the precharge amount and active material powder composed of cadmium oxide which is a main active material are used as a binder such as hydroxypropyl cellulose as a binder and a reinforcing material. It is manufactured by applying a paste made by adding polypropylene fiber, etc. on both sides of a punching metal and drying it, and the fiber as a reinforcing material added in addition to the paste increases the plate strength and gas. The absorption performance is improved.

However, as described above, even if the electrode plate is formed by adding the fiber as the reinforcing material in addition to the paste, it is not possible to prevent the active material powder on the surface of the electrode plate from falling off, and the electrode plate capacity decreases. At the same time, there is a problem that the work environment deteriorates. Generally, it is possible to increase the holding power of the active material and increase the electrode plate strength by increasing the addition amount of the paste as a binder, but in this case, the increase of the paste deteriorates the particle conductivity between the active material particles. Therefore, there is a limit to the amount of addition, and it is unavoidable that the active material powder falls off to some extent.

In addition, unlike the sintered electrode plate, the paste cathode plate does not have a conductive matrix of sintered metal in the active material layer, and cadmium oxide, which is the main component of the active material layer, has a low electronic conductivity, so charging is not possible. Metal cadmium generated at the time is unevenly distributed in the vicinity of the conductive core, and metal cadmium is difficult to be generated on the surface of the cathode plate which is easily contacted with oxygen gas generated from the anode due to overcharge, so that metal cadmium and oxygen gas There has been a problem that the oxygen gas absorption performance for eliminating oxygen gas by the reaction is poor.

(C) Object of the present invention In view of such a point, the present invention prevents the active material from falling off by forming a carbon thin film layer on the surface of the cadmium active material layer by using a water-soluble paste, and has a high rate discharge characteristic and oxygen. A paste formula that improves gas absorption performance and prevents deterioration of battery performance by preventing unevenness in the thickness of the carbon thin film layer and formation of a carbon layer on the exposed portion of the core body of the electrode plate that is the lead-out portion to the cathode terminal. A method for manufacturing a cadmium cathode plate is provided.

(D) Structure of the invention The method for producing a paste-type cadmium cathode plate of the present invention is a method in which a paste containing a cadmium compound as a main component is applied to the surface of a conductive core such as a punching metal to form a semi-dried active material layer. After being formed, a slurry in which carbon powder is dispersed in a water-soluble paste solution is sequentially used from a roller partially immersed in the slurry liquid by using a transfer roller group in which at least two rollers are connected to each other. The thickness of the active material layer is finally adjusted by transferring it to a matching roller, and is then applied to the surface of the active material layer, followed by main drying.

(E) Example An example of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is an explanatory view of a paste-type cadmium cathode plate manufacturing apparatus. By using this electrode plate manufacturing apparatus, a strip-shaped conductive core body (7) made of punching metal is led out from an unwinding roller (1). While being wound by the take-up roller (6), the slurry containing the cadmium compound as a main component is applied by passing through the active material slurry tank (2) and is located above the active material slurry tank (2). After the coating thickness is adjusted by the slits (8), the active material layer is first formed on the surface of the conductive core by being dried by the intermediate dryer (3).
Next, the conductive core having the active material layer formed on the surface is
While passing through the transfer roller device (4), the carbon slurry in which the carbon powder is uniformly dispersed in the water-soluble paste solution is applied to only the surface of the active material layer with a constant thickness, and then the main dryer (5 ), It becomes a completed electrode plate having a carbon thin film layer on the surface of the active material layer.

In this manufacturing method, since the intermediate dryer (3) and the main dryer (5) perform drying in two steps, the intermediate dryer (3) does not need to be completely dried in advance, and the subsequent main dryer can be used. (Five)
Since it is possible to fully dry with
It is sufficient for the intermediate dryer (3) to dry the active material such that the active material does not adhere to the rollers of the apparatus and the active material layer does not collapse while passing through the transfer roller apparatus. In addition, the active material layer obtained by the drying in a state where the inside is slightly wet and the outside is dried to some extent has a carbon thin film layer formed by coating on the surface as compared with a completely dried active material layer. The binding property is good, and the carbon thin film layer is unlikely to fall off or peel off after the electrode plate is completed.

2 and 3 are a perspective view of the transfer roller device and a partial cross-sectional view showing a contact state between the transfer roller and the electrode plate. The transfer roller device is shown in FIG. A transfer roller group including a first transfer roller (10), a second transfer roller (11), and a third transfer roller (12) arranged on each surface, and the second transfer roller (11) The third transfer roller (12) has long holes (13) (14) for adjusting the distance between the transfer rollers by sliding the third transfer roller (12) in parallel with the first transfer roller (10). The transfer roller (10) (11) (12) to rotate the drive unit (15), and a carbon slurry tank (16) having a slurry solution containing carbon powder dispersed in a water-soluble paste The first transfer roller 10 is partially immersed in the slurry solution. In this transfer roller device, by rotating each transfer roller (10) (11) (12),
Carbon slurry adheres to the surface of the transfer roller (10) of the first transfer roller.
The thickness is adjusted by the gap between the (10) and the second transfer roller (11), and it is transferred onto the surface of the second transfer roller (11). Then, similarly, the second transfer roller (11) and the third
The final thickness is adjusted by the gap between the second transfer roller (12) and the third transfer roller (12) to be transferred to the surface of the third transfer roller (12).
The transfer roller (12) is attached to the surface of the active material layer of the electrode plate (9). Further, here, the third transfer roller (12) contacts only the surface of the active material layer (17) of the electrode plate as shown in FIG. 3, so that the exposed portion of the conductive core (18) is not exposed. No carbon thin film layer is formed.

Therefore, since the amount of carbon slurry to be mounted by the transfer roller device can be made uniform on the surface of the active material layer, there is no place where the electron conductivity is partially lowered on the surface of the electrode plate. Since the carbon thin film layer is not formed on the exposed portion of the core body where the carbon slurry is hard to bind, the method of applying the carbon slurry by spraying and the so-called dipping in which the electrode plate is passed through the carbon slurry Thus, the carbon thin film layer does not fall off from the exposed core portion when the carbon thin film layer is formed, and the deterioration of the battery performance due to peeling does not occur.

Then, as a carbon slurry, pure water, hydroxypropyl cellulose, and graphite were mixed in a weight ratio of 100: 20:
2000cps (at25
A paste type cadmium cathode plate having a carbon thin film layer having a thickness of about 5 μm on the surface of the active material layer is produced by the above-mentioned electrode plate producing apparatus using a slurry solution having a viscosity of (° C.). Is cut into a predetermined size and combined with a known nickel anode plate, the nominal capacity is 1200 m
An AH nickel-cadmium battery was obtained.

The paste-type cathode plate manufactured by the manufacturing method according to the present invention was excellent in that the active material powder and the carbon powder did not fall off because the surface strength was increased by the water-soluble paste. On the other hand, a conventional cathode plate made by applying an active material to the conductive core and drying it will drop a large amount of active material powder when the surface is touched, so it does not fall off during the battery assembly process. There is a possibility that the working environment will be impaired by the active material powder that is generated and that the electrode plate capacity will be reduced by the active material powder that has fallen off, so that there will be variations in the electrode plate capacity. It was also found that the battery using the cathode plate of the present invention is superior in oxygen gas absorption performance and high rate discharge characteristics to the battery using the conventional cathode plate. Inferring the reason for this, the oxygen gas absorption performance was excellent because in the battery using the cathode plate of the present invention, metal cadmium with good electron conductivity gradually generated from the vicinity of the conductive core during charging was gradually formed. When the carbon thin film is distributed toward the surface of the electrode plate and reaches a carbon thin film layer on the surface of the electrode plate at a certain part, it means that the conductive core and the carbon thin film layer are electrically connected, and thus the carbon thin film has good electron conductivity. It is considered that because a large amount of metal cadmium is generated on the surface of the electrode plate by receiving power from the layer, the oxygen gas generated from the anode during overcharge reacts with the metal cadmium on the surface of the cathode plate and absorbs oxygen gas. It is considered that the excellent discharge characteristics were due to the fact that the water-soluble paste gelled when it came into contact with the alkaline electrolyte and the amount of electrolyte retained between the cathode and anode plates increased, and when the internal resistance of the battery in a discharged state was measured. According to the invention Battery using the electrode plate was suppressed to a low value compared with conventional batteries.

Needless to say, temperature control of the slurry is important because the thickness of the carbon thin film layer formed on the surface of the cathode plate of the present invention affects the viscosity of the carbon slurry.

(F) Effect of the invention The paste-type cadmium cathode plate of the present invention has at least after forming an active material layer by applying a paste or slurry mainly containing a cadmium compound on the surface of the conductive core and drying the active material layer. Using a transfer roller group consisting of two rollers, the slurry in which the carbon powder is dispersed in the water-soluble paste solution is sequentially transferred to the adjacent rollers to adjust the thickness and apply it to the surface of the active material layer. Since it is deposited and dried, it is possible to form a uniform carbon thin film layer on the surface of the active material layer, and the active material powder does not fall off due to this carbon thin film layer, and the oxygen gas absorption performance and high rate discharge can be achieved. A paste type cadmium cathode plate having good characteristics can be obtained.

[Brief description of drawings]

1 to 3 relate to an embodiment of the present invention. FIG. 1 is an explanatory view of an apparatus for manufacturing a paste type cadmium cathode plate, FIG. 2 is a perspective view of a transfer roller device, and FIG. 3 is a transfer roller. It is sectional drawing which shows the contact state of an electrode plate. (2) ... Active material slurry tank, (3) ... Intermediate dryer, (4) ... Transfer roller device, (5) ... Main dryer, (7) ... Conductive core, (10)
… First transfer roller, (11)… Second transfer roller, (1
2) ... Third transfer roller, (16) ... Carbon slurry tank.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroshi Sakai 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Haraguchi 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Denki Co., Ltd. (56) References JP-A-53-86442 (JP, A) JP-A-54-93429 (JP, A) Moriyasu Matsutani "Additional Painting and Painting Equipment" (Sho 45-11-20) Technical Institute P. 96-97

Claims (1)

[Claims] 1. A paste or slurry mainly containing a cadmium compound is applied to the surface of a conductive core to form an active material layer in a semi-dried state, and then carbon particles are dispersed in a water-soluble paste solution. Characterized in that the slurry is applied to the surface of the active material layer by sequentially transferring the slurry to adjacent rollers using a transfer roller group consisting of at least two rollers, and then performing main drying. Method for manufacturing paste type cadmium cathode plate.