JP5355052B2 - Method for producing sintered nickel substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a sintered substrate with filling volumes of active materials made equal at each column, even in the case of making the substrate on which a plurality of columns are formed at the same time. <P>SOLUTION: The manufacturing method of the nickel sintered substrate is provided with: a slurry coating process of coating nickel slurry 12 containing nickel powder, a hole-making agent and a thickener on a conductive core body 11 so as to have three or more columns of sintered substrates formed and with a coating thickness at an end column to be larger than that of a middle column to make up a slurry-coated substrate 11a; a drying process of drying the slurry-coated substrate 11a to make up a slurry dried substrate 11b; a thickness adjusting process of adjusting thickness of each column of the slurry dried substrate to make up a thickness adjusted substrate 11c; and a sintering process of sintering the thickness adjusted substrate 11c with a sintering furnace 112. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a nickel sintered substrate used in an alkaline storage battery such as a nickel-hydrogen storage battery or a nickel-cadmium storage battery, and in particular, a nickel slurry is applied to a conductive core and then sintered to form a plurality of three or more rows. The present invention relates to a method for manufacturing a nickel-sintered substrate that simultaneously forms a row of sintered substrates.

  In recent years, secondary batteries have been used in a wide variety of applications, such as mobile phones, personal computers, electric tools, electric bicycles, hybrid vehicles, and electric vehicles. Among these applications, alkaline storage batteries are widely used, particularly in vehicle-related applications such as hybrid vehicles and electric vehicles. And in the alkaline storage battery used for these uses, the request of high output and long life is increasing. Further, in vehicle-related applications, since a large number of single cells are connected in series as an assembled battery, the demand for reducing the capacity variation of individual batteries has become particularly strong.

  By the way, although a nickel positive electrode plate is used for the positive electrode of the alkaline storage battery, a nickel sintered substrate is generally used as a substrate material of the nickel positive electrode plate used for such applications that require a high output and a long life. It is. This is because the nickel skeleton that is the skeleton of the nickel sintered substrate is dense and retains conductivity over a long period of time. When producing a nickel positive electrode plate using such a nickel sintered substrate, the positive electrode active material (nickel hydroxide) is filled into the pores of the nickel sintered substrate by an impregnation method. For this reason, in order to reduce the capacity variation (variation in the amount of filling of the active material) of each battery, it has been required to reduce the thickness variation of the nickel sintered substrate.

  Therefore, although the thickness of the nickel sintered substrate after sintering has been rolled, the rebound caused by the springback phenomenon of the nickel skeleton has occurred after rolling, and the thickness variation may not be improved. . In this case, when strongly rolled to improve the thickness variation, the nickel skeleton after sintering is cut, resulting in a new problem that the strength decreases and the conductivity decreases between the active materials. . Therefore, for example, Patent Document 1 (Japanese Patent Laid-Open No. 5-174814) proposes a technique for suppressing fluctuations in the thickness of the nickel sintered substrate by adding a thickness adjusting step of about 0 to 40 μm to the dry substrate. It became so.

In the method of adjusting the thickness of the sintered nickel substrate proposed in Patent Document 1 described above, since it is before sintering, a resin material (gelled thickener or pore former) is held between the nickel powders. Has been. For this reason, partial deformation is unlikely to occur, and the nickel skeleton is formed by sintering in the subsequent process, so there is no risk of nickel skeleton cutting or springback phenomenon, producing a stable nickel sintered substrate. It becomes possible to do. Thereby, since the thickness variation of the nickel sintered substrate is reduced, the variation in the filling amount of the active material is reduced, and the variation in the battery capacity can be reduced.
JP-A-5-174814

  By the way, when manufacturing this kind of nickel sintered substrate, a manufacturing method is adopted in which three or more rows are simultaneously formed from the viewpoint of productivity and production efficiency. For this reason, in the step of impregnating the active material of the nickel sintered substrate thus manufactured, the middle row (the central row other than both ends) and the end row (both ends) are affected by environmental influences. Easiness (for example, easiness of drying, easiness of liquid treatment, etc.) will be different. As a result, the active material mass filled in the middle row and the end row varies, and in particular, there is a problem that the active material filling amount in the end row is lower than that in the middle row.

  In this case, in particular, in the high-power type nickel positive electrode plate that needs to increase the reaction area by expanding the facing area of both positive and negative electrodes, it is necessary to reduce the thickness of the nickel positive electrode plate, It is necessary to reduce the thickness of the nickel sintered substrate. However, as the thickness of the nickel-sintered substrate becomes thinner, variation in the amount of active material filling among the plurality of rows tends to occur, so the effect of reducing the thickness of the nickel-sintered substrate becomes greater. It became the situation. In view of this, for example, a coping method has been considered in which the thickness of the end row of the nickel sintered substrate is made thicker than that of the middle row so that a large amount of active material is easily filled.

  However, it is difficult to increase only the thickness of the end rows by rolling, and even if only the thickness of the end rows can be increased, a difference in thickness occurs between a plurality of rows. In this case, normally, the produced sintered substrate composed of a plurality of rows is wound into a coil shape and sent to the next step. However, when a thickness difference occurs between the plurality of rows, meandering occurs in the obtained plurality of rows of sintered substrates, or the obtained plurality of rows of sintered substrates are wound into a coil shape and wound up. When a coil is used, a new problem has arisen in that a winding deviation occurs in the winding coil and the coil cannot be easily handled.

Therefore, the present inventors have made various studies, and the end row is easier to be dried and liquid-treated than the middle row, so that the end row tends to have a smaller amount of active material, Although the liquid permeated by impregnation, the impregnating liquid of the substrate surface layer tends to sag, and thus the knowledge that the influence becomes more noticeable as the thickness of the sintered substrate becomes thinner is obtained.
The present invention has been made based on the above knowledge, and provides a method for manufacturing a sintered substrate in which the amount of active material in each row is equal even when a plurality of rows are formed simultaneously. It was made for the purpose of doing.

  The present invention relates to a method of manufacturing a nickel sintered substrate in which a nickel slurry is applied to a conductive core and then sintered to simultaneously form a plurality of rows of sintered substrates of three or more rows. A nickel slurry containing an agent and a thickener is applied to the conductive core so that three or more rows of sintered substrates are formed and the thickness of the end row is greater than the thickness of the middle row. The thickness of the thickness adjustment substrate by adjusting the thickness so that the thickness of each row of the slurry drying substrate is equal, the slurry coating step of making the slurry coating substrate, the drying step of drying the slurry coating substrate to make the slurry drying substrate An adjustment step and a sintering step for sintering the thickness adjustment substrate are provided.

  Here, when the nickel slurry is applied to the conductive core so that the coating thickness of the end row is larger than the coating thickness of the middle row, the amount of nickel in the end row increases. And after drying the slurry-coated substrate in which the amount of nickel in the end row is increased, and adjusting the thickness so that the thickness of each row of the slurry dry substrate is equal, variation in thickness between rows is suppressed, It becomes possible to improve the retention performance of the active material in the end row. As a result, it is possible to obtain a coiled nickel sintered substrate that suppresses a decrease in mass of the active material in the end row with respect to the middle row and does not generate meandering or winding deviation during coil winding.

In this case, it has been clarified that when the coating thickness of the end row is an increase of 5 μm or more with respect to the coating thickness of the middle row, the effect of suppressing the decrease in the active material mass of the end row with respect to the middle row is great. On the other hand, if the coating thickness of the end row is an increase amount exceeding 20 μm with respect to the coating thickness of the middle row, the thickness of the end row of the slurry dry substrate becomes too large, so that each row has the same thickness. When rolling is attempted, wrinkles of the slurry dry substrate due to thickness variation between rows due to repulsion of the slurry dry substrate (springback) and rolling unevenness (partial elongation of the slurry dry substrate where a strong rolled portion occurs) are generated. become. Therefore, in the slurry coating step, you nickel slurry so thick as 20μm or less 5μm or more than the coating thickness of the medium is the coating thickness of the end column column as applied.

  In addition, when the fixed thickness is adjusted by rolling with a pair of rotating rollers, it is possible to prevent damage such as scratches on the slurry dry substrate, and the slurry dry substrate is less likely to be distorted. In addition, since the damage to the rotating roller is small, it is desirable to adjust the thickness by allowing the slurry dry substrate to pass between the pair of rotating rollers. Further, since the thickness of the slurry drying substrate may change randomly depending on the drying method, it is desirable to use a rotating roller that can easily adjust the roller interval and its inclination.

  In the nickel sintered substrate of the present invention, the amount of the active material filling tends to decrease and the amount of the nickel slurry applied to the end row where the impregnating liquid of the substrate surface layer is liable to drip is increased although the liquid penetrates by impregnation. Therefore, it is possible to obtain an electrode plate with less variation in the filling amount of the active material and less variation in battery capacity.

  Below, one Embodiment of the manufacturing method of the nickel sintered substrate applied to the nickel electrode plate of a nickel-hydrogen storage battery is described based on FIG. 1 and FIG. FIG. 1 is a cross-sectional view schematically showing an example of a schematic configuration of the method for producing a sintered substrate of the present invention. FIG. 2 is a graph showing the relationship between the increase in coating thickness at the end row and the reduction ratio of the active material at the end row.

1. First, a nickel sintered substrate manufacturing apparatus 100 as shown in FIG. 1 is prepared. Here, the nickel sintered substrate manufacturing apparatus 100 includes an unwinding roll 101 that winds the conductive core material 11 made of a nickel-plated perforated steel sheet in a roll shape, and rolls the obtained sintered substrate. A winding roll 102 that winds the conductive core material 11, transport rollers 103, 104, 105, 106, and 107 that transport the conductive core material 11, and a slurry tank 108 that applies nickel slurry 12 to the conductive core material 11. The thickness adjustment slit 109 for adjusting the slurry to a predetermined thickness to form the slurry-coated substrate 11a, the dryer 110 that dries the slurry-coated substrate 11a to form the slurry-dried substrate, and the thickness of the slurry-dried substrate 11b are adjusted. A thickness adjusting rotary roller 111 and a sintering furnace 112 for sintering the adjusted slurry dry substrate 11b in a reducing atmosphere. It is configured. Here, the thickness adjusting slits 109 are divided into a plurality of rows, and the slit widths of the plurality of rows of slits 109 can be individually adjusted.

  The conductive core material 11 is made of, for example, a perforated steel sheet having a thickness of 60 μm, and the surface thereof is plated with nickel having a thickness of 5 μm, and a plurality of rows (for example, 5 to 8 rows) of nickel baked steel. Perforations are made so as to form a predetermined arrangement so that a bonded substrate is formed. In this case, the conductive core material 11 made of a nickel-plated perforated steel sheet was placed in a predetermined position on the unwinding roll 101 wound in a roll shape, and then wound on the unwinding roll 101. The leading end of the conductive core material 11 is the transport roller 103, the transport roller 104 in the slurry tank 108, the thickness adjusting slit 109, the dryer 110, the thickness adjusting roller 111, the transport rollers 105 and 106, the inside of the sintering furnace 112, and the transport roller. It is assumed that it is wound around the winding roll 102 through 107.

Next, nickel with a bulk density of 0.57 g / cm ³ and a Fisher size (meaning that this Fisher size is the average particle size measured with a Fisher Sub-Sieve Sizer) is 2.5 μm. 40 parts by mass of powder, 0.1 part by mass of a completely foamed organic hollow body (average particle size is 60 μm) mainly composed of a methyl methacrylate-acrylonitrile copolymer as a pore-forming agent, and 3% by mass as a thickener A nickel slurry 12 was prepared by kneading 60 parts by mass of an aqueous methylcellulose solution under vacuum. Next, after the nickel slurry 12 thus prepared is accommodated in the slurry tank 108, the winding core 102 is wound up at a predetermined speed, whereby the conductive core wound around the winding roll 101 in a roll shape. The material 11 is unwound from the unwinding roll 101.

  Thereby, the nickel slurry 12 is applied to both surfaces of the conductive core material 11 in the process of passing through the nickel slurry 12 in the slurry tank 108. Then, when the conductive core material 11 passes through the thickness adjusting slit 109, the excess nickel slurry 12 is scraped off, so that the slurry coating substrate 11a with the coating thickness adjusted is formed. In this case, by adjusting the slit widths of the plurality of rows of the slits 109 for adjusting the thickness individually, the thickness of the slurry coating substrate 11a in the middle row becomes 670 μm, and the thickness of the slurry coating substrate 11a in the end row is 670 μm, (670 + 3) μm, (670 + 5) μm, and (670 + 10) μm.

  Here, the slurry-coated substrate 11a applied so that the thickness of the end-row slurry-coated substrate 11a is (670 + 3) μm was defined as the slurry-coated substrate a1. Similarly, the slurry-coated substrate 11a applied so as to be (670 + 5) μm was designated as a slurry-coated substrate b1, and the slurry-coated substrate 11a applied so as to be (670 + 10) μm was designated as a slurry-coated substrate c1. Further, the slurry-coated substrate 11a coated so that the thickness of the slurry-coated substrate 11a in the end row is equal to the thickness of the slurry-coated substrate 11a in the middle row is 670 μm was used as the slurry-coated substrate d1.

The slurry coated substrate 11a (a1, b1, c1, d1) thus formed enters the dryer 110 whose temperature is maintained at 800 ° C., and the slurry coated substrate 11a is dried to form the slurry dried substrate 11b. It becomes. At this time, the rotation speed of the take-up roll 102 is adjusted so that the time spent in the dryer 110 is 30 seconds. Next, the obtained slurry dry substrate 11b is passed between a pair of thickness adjusting rotating rollers 111, whereby the thickness of each row of the slurry dry substrate 11b becomes equal (the thinnest of the slurry dry substrates 11b is the thinnest). The thickness adjustment substrate 11c (a2, b2, c2, d2) is formed by adjusting so that the thickness is reduced by at least 20 μm in the row.
In addition, after drying the slurry application | coating board | substrate d1 to make the slurry dry board | substrate 11b, what was not allowed to pass between the rotation rollers 111 for thickness adjustment was made into thickness non-adjustment board | substrate e2. In this case, a substrate using the slurry application substrate a1 is a thickness adjustment substrate a2, a substrate using the slurry application substrate b1 is a thickness adjustment substrate b2, and a substrate using the slurry application substrate c1 is a thickness adjustment substrate c2. A substrate using the substrate d1 was designated as a thickness adjusting substrate d2.

  Next, the thickness-adjusted substrates (a2 to d2) and the non-thickness-adjusted substrates e2 that were adjusted as described above were allowed to pass through the sintering furnace 112. In this case, the inside of the sintering furnace 112 is heated to a temperature of about 900 to 1000 ° C. in a reducing atmosphere containing hydrogen, and the thickness adjusting substrates (a2 to d2) and the non-thickness adjusting substrate e2 are used as the sintering furnace. By passing through 112, the coiled nickel sintered substrate 10 (a3 to e3) is formed. At this time, the sintering temperature and the sintering time were adjusted so that the nickel sintered substrate 10 (a3 to e3) had a predetermined thickness t (in this case, t = 370 μm) and the porosity was 85%. .

  In addition, what used the thickness adjustment board | substrate a2 was used as the sintering board | substrate a3. Similarly, a substrate using the thickness adjusting substrate b2 is a sintered substrate b3, a substrate using the thickness adjusting substrate c2 is a sintered substrate c3, and a substrate using the thickness adjusting substrate d2 is a sintered substrate d3. A substrate using the non-thickness adjusting substrate e2 was used as a sintered substrate e3.

2. Active material-filled electrode plate Next, a coiled nickel sintered substrate (a3 to e3) having a porosity of about 85% produced as described above is immersed in a mixed aqueous solution of nickel nitrate and cobalt nitrate having a specific gravity of 1.75. Thus, the nickel salt and the cobalt salt were held in the pores of the porous nickel sintered substrate 31. Thereafter, the porous nickel sintered substrate was immersed in a 25% by mass sodium hydroxide (NaOH) aqueous solution to convert the nickel salt and the cobalt salt into nickel hydroxide and cobalt hydroxide, respectively. Then, after sufficiently washing with water to remove the alkaline solution, drying was performed, and the active material mainly composed of nickel hydroxide was filled in the pores of the porous nickel sintered substrate (a3 to e3).

  Such an active material filling operation is repeated a predetermined number of times (for example, 6 times), and nickel in which an active material mainly composed of a predetermined amount of nickel hydroxide is filled in the pores of the porous sintered substrates (a3 to e3). Positive electrode plates (A to E) were produced. A nickel positive electrode plate A was prepared using the nickel sintered substrate a3. Similarly, the one using the nickel sintered substrate b3 is a nickel positive plate B, the one using the nickel sintered substrate c3 is the nickel positive plate C, and the one using the nickel sintered substrate d3 is the nickel positive plate D. did. Also, a nickel positive electrode plate E was used which used the nickel sintered substrate e3.

3. Measurement of active material filling amount Each of the nickel positive electrode plates (A to E) produced as described above was cut into a predetermined size, and then the mass of each of the nickel positive electrode plates (A to E) after cutting was measured. And from the difference with the mass of each nickel sintered substrate (a3-e3) when it cut | disconnects to the same dimension measured beforehand, the active material mass of each nickel positive electrode plate (AE) after a cutting | disconnection is calculated. did. In this case, with respect to the calculated active material mass of each of the nickel positive electrode plates (A to E), the average value in each row of the plurality of rows is calculated, and the ratio of the difference from the average value of the active material mass in the end row When the (decrease ratio of the active material in the end row) was calculated, the results shown in Table 1 below were obtained.

In addition, about the difference with the average value of the active material mass in an end row, the active material mass of each end row was compared, and it was set as the difference with the one with a larger difference. In addition, when the active material mass deviates from a preset reference value (target value) by more than ± 5%, it is determined to be defective, and the ratio (defective rate) of those determined to be defective is calculated. The results shown in Table 1 below were obtained. Then, from the results in Table 1, when the amount of increase in the coating thickness of the end row is plotted on the horizontal axis (X axis) and the decrease ratio of the active material in the end row is plotted on the vertical axis (Y axis), The result was as shown.

  As is clear from the results of Table 1 and FIG. 2, the nickel positive electrode plate D and the nickel positive electrode plate E have a large reduction ratio of the active material in the end row and a large defect rate, whereas the nickel positive electrode plate A, It can be seen that the nickel positive electrode plate B and the nickel positive electrode plate C have a small reduction rate of the active material in the end row and a small defect rate. This is because, in the nickel positive plates A, B, and C, the thickness of the nickel slurry in the end row is increased with respect to the middle row, and the thickness is adjusted by a pair of rotating rollers. Since the variation can be reduced, it is considered that the reduction ratio of the active material in the end row is lowered.

In this case, as in the case of the nickel positive plates B and C, when the thickness of the nickel slurry in the end row is increased by 5 μm or more with respect to the middle row and the thickness is adjusted by a pair of rotating rollers, the reduction ratio of the active material in the end row It can be seen that it can be reduced to 1.1% or less. On the other hand, although data is not shown, if the thickness of the nickel slurry in the end row is increased to exceed 20 μm with respect to the middle row, it is strong in the thickness adjustment step (rolling step with a pair of rollers) for adjusting to a constant thickness. Since it is necessary to perform rolling, a situation occurs in which wrinkles are generated in a part of the slurry dry substrate due to strong rolling. For these reasons, the coating thickness of the end column relative the middle column 5μm or more, you increase the coating thickness so as to 20μm or less.

  For such thickness adjustment, if the thickness adjustment is performed with a pair of rotating rollers as in the present invention, there is an effect of reducing damage to the slurry dry substrate (such as scratches), and that distortion is less likely to occur, There is little damage to the rollers. Furthermore, since the thickness of the slurry drying substrate may change randomly depending on the drying method, it is desirable to use a rotating roller that can adjust the roller interval and its inclination.

  In the embodiment described above, the example in which the nickel sintered substrate of the present invention is applied to the nickel positive electrode plate of the nickel-hydrogen storage battery has been described. However, the nickel sintered substrate of the present invention is not limited to the nickel-hydrogen storage battery. It is obvious that the present invention can also be applied to nickel-sintered positive and negative plates of other alkaline storage batteries such as nickel-cadmium storage batteries.

It is sectional drawing which shows typically an example of schematic structure of the manufacturing method of the sintered substrate of this invention. It is a graph which shows the relationship between the coating thickness increase amount of an edge row, and the reduction | decrease ratio of the active material of an edge row.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Nickel sintered substrate, 11 ... Conductive core, 11a ... Slurry coating substrate, 11b ... Slurry dry substrate, 11c ... Thickness adjustment substrate, 12 ... Slurry, 100 ... Sintered substrate manufacturing apparatus, 101 ... Unwinding roll, DESCRIPTION OF SYMBOLS 102 ... Winding roll, 103, 104, 105, 106, 107 ... Conveyance roller, 108 ... Slurry tank, 109 ... Thickness adjustment slit, 110 ... Dryer, 111 ... Thickness adjustment rotary roller, 112 ... Sintering furnace

Claims (2)

A method for producing a nickel sintered substrate, in which a nickel slurry is applied to a conductive core and then sintered to simultaneously form a plurality of rows of sintered substrates of three or more rows,
A nickel slurry containing nickel powder, a pore former and a thickener is formed so that three or more rows of sintered substrates are formed and the coating thickness of the end rows is larger than the coating thickness of the middle row. A slurry application step that is applied to the core body to form a slurry application substrate;
A drying step of drying the slurry-coated substrate to form a slurry-dried substrate;
Thickness adjustment step to adjust the thickness so that the thickness of each row of the slurry dry substrate is equal to the thickness adjustment substrate,
A sintering step of sintering the thickness adjusting substrate ,
In the slurry application step, the nickel slurry is applied to the conductive core so that the coating thickness of the end row is 5 μm or more and 20 μm or less thicker than the application thickness of the middle row. A manufacturing method of a bonded substrate. 2. The nickel sintered substrate according to claim 1, wherein the thickness of each row of the slurry dry substrates is made equal by passing the slurry dry substrate between a pair of rotating rollers in the thickness adjusting step. Manufacturing method.

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