JP2007280922A - Manufacturing method of electrode for battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrode for a battery with high precision in which a mixture paste is utilized with high yield, and variations in the width of unpainted portion leading directly to welding failure of the unpainted portion and a current collector and distortion of electrodes can be reduced. <P>SOLUTION: The manufacturing method of the electrode for battery comprises a painting process to coat continuously a mixture paste containing an active material on the core material made of continuous three-dimensional metal porous body. A pretreatment process in which an unpainted portion is provided by regulating the running position of the core material while interposing a part of the core material to make it in high density is provided before applying the painting process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a battery electrode, and more particularly to a method for stably and continuously producing an electrode for an alkaline storage battery.

  Applications of batteries such as alkaline storage batteries are expanding from the power source of portable devices to the power source of electric tools and the auxiliary power source of electric vehicles. Along with this, improvement of the high rate discharge characteristics is strongly demanded, and as one of the countermeasures, a mixture paste that forms an uncoated part on one side along the longitudinal direction of the electrodes (positive electrode and negative electrode) In order to prevent the uncoated portions of the positive electrode and the negative electrode from facing each other, the electrode groups are formed by winding them in a spiral shape in a state of being alternately stacked with separators interposed between them. The structure which welds a positive electrode current collecting plate and a negative electrode current collecting plate is taken. As an advantage of this configuration, unlike the conventional technique in which the lead is joined to only one end in the longitudinal direction, current can be collected from the entire circumference of the positive electrode and the negative electrode, so that the internal resistance is drastically reduced and the high rate discharge characteristics can be improved.

Electrodes made by filling a three-dimensional metallic porous material with a mixture such as an active material have been put to practical use mainly in the positive electrode of alkaline storage batteries from the viewpoint that a large amount of these mixtures can be held in the electrode with a small amount of binder. Is spreading. However, it is difficult to accurately form an uncoated portion on such an electrode. Therefore, after filling the mixture paste into the three-dimensional metal porous body, the part that hits the coating part is pressed by a stripe roll press machine, while the part that hits the uncoated part is not left as a remaining convex part, and this part is pressed. There has been proposed a method of removing the active material by applying ultrasonic vibration to the material (for example, Patent Document 1). In addition, a method has been proposed in which a nozzle that discharges a mixture paste is brought close to a core material such as a three-dimensional metal porous body to discharge the mixture paste and provide a coating portion that is narrower than the core material (for example, a patent) Reference 2).
Japanese Patent Laid-Open No. 2002-075345 Japanese Patent No. 2976863

  However, the method of Patent Document 1 cannot be said to be efficient because the removed mixture paste is lost. In that respect, the method of Patent Document 2 has the advantage that loss of the mixture paste does not occur, but the mixture paste dripping at both ends of the coating portion immediately after coating causes a large variation in the width of the coating portion. Following this, the variation in the width of the uncoated part also increases, and the mixture left in the uncoated part when welding the positive and negative current collector plates to the upper and lower surfaces of the electrode group The problem that welding becomes inadequate with a paste arises. Further, in order to improve productivity, it is necessary to continuously supply the three-dimensional metal porous body in a hoop shape. However, such a three-dimensional metal porous body is likely to meander during continuous supply. However, since the methods of Patent Documents 1 and 2 do not have means for suppressing the above-described meandering, it is inevitable that the electrode after coating is distorted and curved. This bending further increases the above-described welding defects.

  The present invention has been made to address the above-described problems, and uses the mixture paste at a high yield, and the variation in the width of the uncoated portion that directly leads to a welding failure between the uncoated portion and the current collector plate. It is an object of the present invention to provide a highly accurate battery electrode manufacturing method capable of reducing distortion of electrodes.

In order to achieve the above object, the battery electrode manufacturing method of the present invention includes a coating step of continuously applying a mixture paste containing an active material to a core material composed of a continuous three-dimensional porous metal body. In addition, prior to this coating process, a pre-processing process is provided in which the travel position of the core material is regulated and a part of the core material is sandwiched and densified to provide an uncoated part. .

  Before applying the mixture paste, by densifying a part of the core material and providing an uncoated part, the boundary between the coated part and the uncoated part is clarified and the mixture paste is not coated. It is difficult for the liquid to drip into the part, and the variation in the width of the uncoated part can be reduced. Further, by sandwiching the uncoated part provided in the core material in this process, the running linearity of the core material is improved, and the meandering that is likely to occur during continuous supply due to the three-dimensional metal porous body can be suppressed, and the electrode after coating Can be avoided. Due to these effects, it is possible to avoid welding defects between the uncoated portion and the current collector plate.

  According to the present invention, the mixture paste can be used at a high yield, and the variation in the width of the uncoated part and the distortion of the electrode directly connected to the welding failure between the uncoated part and the current collector plate can be reduced. A battery electrode with high accuracy can be manufactured.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1st invention includes the coating process which coats the mixture paste containing an active material continuously to the core material which consists of a continuous three-dimensional metal porous body, and precedes this coating process, The present invention relates to a method for manufacturing a battery electrode, characterized in that a pretreatment step is provided in which a density is increased while sandwiching a part of the core material while restricting a traveling position and an uncoated portion is provided.

  FIG. 1 is a schematic view of a method for producing a battery electrode of the present invention. The core material 1 (specifically, the three-dimensional metal porous body) travels from the lower side to the upper side in this figure, passes through the core material travel position regulating device 5 and the high-density processing device 6, and then the mixture paste coating device. The electrode 7 is formed by passing through 4 (for example, composed of a nozzle or the like). The obtained electrode 7 has an uncoated portion 2 and a coated portion 3.

  Before passing through the mixture paste coating apparatus 4, a part of the core material 1 is densified to provide an uncoated part 2, thereby clarifying the boundary between the coated part 3 and the uncoated part 2. The agent paste is less likely to drip into the uncoated part 2, and variations in the width of the uncoated part 2 can be reduced. Further, in this process, the core material travel position regulating device 5 regulates the travel position of the core material 1, and the uncoated part 2 provided on the core material 1 is sandwiched by the high-density processing device 6. The running linearity of the material 1 is remarkably improved, the meandering that is likely to occur during continuous supply because of the three-dimensional porous metal body can be suppressed, and bending due to distortion of the electrode 7 after coating can be avoided. Due to these effects, it is possible to avoid welding defects between the uncoated portion 2 and the current collector plate (not shown).

  The densification in the present invention is a general term for reducing the pore volume with a material other than the mixture with respect to the original core material 1.

  Details of the method for producing the battery electrode of the present invention will be described in more detail. FIG. 2 is a schematic cross-sectional view of the high-density treatment apparatus 6 in the present invention, and FIG. 3 is a schematic cross-sectional view of the mixture paste coating apparatus 4 in the present invention. When the core material 1 passes through the core material travel position regulating device 5, the travel position of the core material 1 is regulated. After that, the non-coated part 2 is formed by the high-density processing device 6, but the core material 1 meanders left and right while the core material 1 is traveling in order to sandwich the portion where the high-density processing device 6 becomes the uncoated part 2. Can be suppressed. The electrode 7 obtained through such a manufacturing method has a high linearity at the boundary between the uncoated portion 2 and the coated portion 3 (see FIGS. 4B and 5B). Furthermore, since the meandering at the time of coating is suppressed, it is possible to avoid the curvature that becomes prominent in the rolling process performed after coating.

On the other hand, if the high-density treatment device 6 is omitted, the core material 1 slightly snakes and the mixture paste drips into the uncoated part 2, so that the uncoated material is not applied as shown in FIG. Variations in the width of the part 2 occur, and welding defects become conspicuous. Further, if the core material travel position regulating device 5 is omitted, the meandering becomes intense and the waviness phenomenon of the coating part 3 occurs as shown in FIG. This phenomenon is not only directly connected to the variation in the width of the uncoated part 2, but also causes the electrode 7 to be bent after the rolling process, so that the welding failure between the uncoated part 2 and the current collector plate becomes noticeable.

  The second invention is characterized in that, in the first invention, both end portions of the core material 1 are uncoated portions 2 in the pretreatment step. By sandwiching both end portions of the core material 1 having the highest position regulating effect as the uncoated portion 2, the meandering prevention effect is further increased, and the curvature that becomes prominent in the rolling process performed after coating can be avoided.

  The third invention is characterized in that, in the first invention, the uncoated portion 2 is provided by compressing the core material 1 in the pretreatment step. Among the methods of providing the non-coated portion 2 subjected to the densification treatment, this method has the highest productivity because it does not require other members.

  A fourth invention is characterized in that, in the first invention, the uncoated portion 2 is provided by bonding the same material as the core material 1 to the core material 1 in the pretreatment step. By increasing the metal weight per unit area of the uncoated portion 2, welding with the current collector is easier than that according to the third invention, but an increase in the number of members to be prepared is inevitable. Among them, the fourth method can use the same material as the core material 1 (for example, a part of the core material 1 processed into a slice or a reel), so that it is not necessary to substantially increase the number of parts. .

  The fifth invention is characterized in that, in the first invention, the uncoated portion 2 is provided by bonding a metal plate to the core material 1 in the pretreatment step. Although this method increases the number of parts compared to the method described in the fourth invention, it is preferable because it can be more easily welded to the current collector. The metal plate can be freely selected as long as it is an electrochemically stable material in a battery environment. Specifically, a nickel plate, a steel plate plated with nickel, and the like can be mentioned.

  The present invention is mainly useful as a method for producing a positive electrode for an alkaline storage battery. The positive electrode mixture paste for alkaline storage batteries consists of nickel hydroxide, which is an active material, rare earth oxides and zinc oxide, which are additives for improving high temperature characteristics, and polytetrafluoroethylene ( PTFE) and the like, carboxymethyl cellulose (CMC), xanthan gum and the like as a thickener are mixed with a solvent such as water. The core material 1 is a continuous three-dimensional metal porous body. Specifically, a band-like continuous body obtained by packing foamed or fibrous nickel or the like mainly on a hoop is used.

  Hereafter, the manufacturing method of the battery electrode in this invention is demonstrated in detail.

Example 1
To 100 parts by weight of nickel hydroxide as an active material, 1.5 parts by weight of ytterbium oxide, 0.1 parts by weight of CMC, 0.1 parts by weight of xanthan gum, 0.3 parts by weight of PTFE (solid content ratio) and an appropriate amount of water In addition, kneading was performed to obtain a mixture paste. This mixture paste is coated on the continuous foamed nickel porous body (width 130 mm, thickness 0.5 mm, porosity 98%, average pore diameter 200 μm) as the core material 20 by the method shown in FIGS. Worked. The coating was performed so as not to be applied to the uncoated portion 2. Here, the uncoated part 2 was provided by compressing the core material 1 to a thickness of 0.1 mm. The width of the uncoated portion 2 was 7 mm, provided at three positions, both ends and substantially the central portion, and the coating amount of the mixture (solid content ratio) in the coated portion 3 was 0.06 g / cm ² .

  Then, it rolled so that the thickness of the coating part 3 might be set to 0.28 mm, and the hoop of the electrode 7 was obtained. This is Example 1.

(Example 2)
In contrast to Example 1, the uncoated portions 2 were not provided at both ends of the core material 1 (the densification process was performed only on the substantially central portion of the core material 1). 7 hoops were produced. This is Example 2.

(Example 3)
In contrast to Example 1, a reel (width 7 mm) made of the same material as the foamed nickel porous body, which is the core material 1, is provided in the vicinity of the high-density treatment apparatus 6, and this is bonded to a thickness of 0.2 mm. A hoop of the electrode 7 was produced in the same manner as in Example 1 except that the coating part 2 was provided. This is Example 3.

Example 4
Compared to Example 1, a nickel reel (width 7 mm) having a thickness of 0.08 mm is provided in the vicinity of the high-density processing apparatus 6 and welded at a welding current value of 3 A, a voltage value of 240 V, and a pressure of 120 N, thereby obtaining a thickness. Was prepared in the same manner as in Example 1 except that an uncoated portion 2 having a thickness of 0.18 mm was provided. This is Example 4.

(Comparative Example 1)
A hoop of the electrode 7 was produced in the same manner as in Example 1 except that the high-density processing apparatus 6 was removed from Example 1. This is referred to as Comparative Example 1.

(Comparative Example 2)
A hoop of the electrode 7 was produced in the same manner as in Comparative Example 1 except that the core material travel position regulating device 5 was further removed from Comparative Example 1. This is referred to as Comparative Example 2.

  The following evaluation was performed on each of the above examples. The results are shown in (Table 1).

(Running linearity)
The deviation from the position of one end of the core 1 that was initially set was measured by a position sensor, and the maximum value of the touch width was recorded in (Table 1) as the meandering position deviation amount.

(Linearity of boundary between coated part 2 and uncoated part 3)
The maximum value of the deflection width with respect to the boundary between the initially set coated part 2 and the uncoated part 3 was measured with an optical microscope at each n = 10 and described in (Table 1).

(Weldability)
The obtained electrode 7 was cut into a width of 50 mm (including an uncoated portion width of 4 mm) and a length of 90 cm, and the negative electrode and the separator were wound together so as to have a diameter of 30 mm. Weld to a 29 mm nickel current collector. Here, the current collector welding strength was confirmed with a tensile strength tester, and those having a tensile strength of 100 N or less were determined as defective welding products, and the occurrence rates thereof are shown in (Table 1).

芯材走行位置規制装置５を設け、かつ高密度処理装置６を芯材１の両端および略中央部に当接する箇所に設けた実施例１は、未塗工部２と塗工部３との境界の直線性が確保できたので、安定した溶接性を示した。ただし高密度処理装置６を芯材１の略中央部に当接する箇所のみに設けた実施例２は、両端部の高密度処理装置６がなく芯材１の狭持が１点のみであったので蛇行位置ズレ量が僅かに増加した上に、未塗工部２の幅のバラツキに起因する溶接不具合の発生率が僅かながら増加した。一方、実施例１に対して金属製の部材を貼り合わせて高密度化処理を行い、未塗工部２を形成した実施例３および４は、実施例１と同等の走行直線性を示すとともに、溶接部位の金属量の増加で塗工部２と未塗工部３との境界直線性が確保できたので、実施例１と同様、溶接性が安定した。

Example 1 in which the core material travel position restricting device 5 is provided and the high-density treatment device 6 is provided at a position where the core material 1 is in contact with both ends and substantially the center portion of the uncoated portion 2 and the coated portion 3. Since the linearity of the boundary was secured, stable weldability was exhibited. However, in Example 2 in which the high-density treatment apparatus 6 is provided only at a position where the high-density treatment apparatus 6 is in contact with the substantially central portion of the core material 1, there is no high-density treatment apparatus 6 at both ends, and the core material 1 is held only at one point. As a result, the amount of deviation of the meandering position slightly increased, and the incidence of welding defects due to variations in the width of the uncoated portion 2 slightly increased. On the other hand, Examples 3 and 4 in which a metal member was bonded to Example 1 and subjected to a densification treatment to form an uncoated part 2 showed traveling linearity equivalent to Example 1. Since the boundary linearity between the coated part 2 and the uncoated part 3 could be secured by increasing the amount of metal at the welded part, the weldability was stabilized as in Example 1.

  On the other hand, in Comparative Example 1 in which the high-density processing device 6 was not provided, although the travel position of the core material 1 was restricted only by the core material travel position restricting device 5, the core material 1 slightly meandered and was not coated. Since the mixture paste drips in the part 2, the width of the uncoated part 2 varies, and the welding failure becomes conspicuous due to the influence of the mixture paste existing in the welded part. Further, in Comparative Example 2 in which the core material travel position restricting device 5 was not provided, the meandering became so intense that a wavy phenomenon occurred at the boundary between the uncoated part 2 and the coated part 3. In Comparative Example 2, the welding defect occurrence rate was remarkably deteriorated as compared with Comparative Example 1. As the reason, the effect of the mixture paste dripping on the uncoated part 2 as in Comparative Example 1, It can be considered that the boundary between the uncoated portion 2 and the coated portion 3 having different volume ratios is not constant due to the undulation, and thus the influence of causing distortion in the subsequent rolling process and inducing the bending of the electrode 7 is considered.

  By utilizing the present invention, an electrode that can be easily welded to a current collector can be stably supplied, so that it is expected to have a great effect on the spread of batteries in fields where a current collector plate is essential, such as a power source for a hybrid vehicle. it can.

Schematic of the manufacturing method of the battery electrode of the present invention Schematic cross-sectional view of a high-density processing apparatus in the present invention Schematic cross-sectional view of a mixture paste coating apparatus in the present invention (A) The top view which shows the linearity of the boundary of the uncoated part and coated part of this invention, (B) The non-coating of the boundary between the uncoated part and the coated part when not providing a high-density processing apparatus Plan view showing linearity (A) Sectional drawing which shows the linearity of the boundary of the uncoated part of this invention, and a coated part, (B) The boundary of the uncoated part and coated part when not providing a core material travel position control apparatus Sectional view showing the non-linearity of

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core material 2 Uncoated part 3 Coating part 4 Compound paste coating apparatus 5 Core material travel position control apparatus 6 High-density processing apparatus

Claims (5)

A method for producing a battery electrode comprising a coating step of continuously applying a mixture paste containing an active material to a core material comprising a continuous three-dimensional metal porous body,
Prior to the coating process, a battery is provided with a pretreatment process in which a travel position of the core material is restricted and a part of the core material is sandwiched and densified to provide an uncoated part. For manufacturing an electrode. The method for manufacturing a battery electrode according to claim 1, wherein in the pretreatment step, both end portions of the core material are uncoated portions. The method for manufacturing a battery electrode according to claim 1, wherein in the pretreatment step, an uncoated portion is provided by compressing the core material. 2. The method for manufacturing a battery electrode according to claim 1, wherein in the pretreatment step, an uncoated portion is provided by bonding the same core material to the core material. The method for manufacturing a battery electrode according to claim 1, wherein in the pretreatment step, an uncoated portion is provided by bonding a metal plate to the core material.

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