JP2009245771A - Alkaline storage battery and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline storage battery with improved reliability by increasing welding current flowing at a contact part of a collector and ends of an electrode, and reducing reactive current flowing in the collector to prevent the occurrence of short circuit at an electrode group through restraint of break or explosion of the collector. <P>SOLUTION: The alkaline storage battery includes a spiral electrode group 10a wound around in a spiral shape, and at the same time, a negative electrode collector 14 is welded to one of the electrode ends 12c of the electrode group 10a, and a positive electrode collector 15 is welded to the other electrode end 11c. Further, a conductive thin film 16 excellent in conductivity is arranged between one of the electrode ends 12c and the negative electrode collector 14, and another conductive thin film 16 excellent in conductivity is arranged between the other electrode end 11c and the positive electrode collector 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an alkaline storage battery such as a nickel-cadmium storage battery or a nickel-hydrogen storage battery, and in particular, an electrode body in which a current collector is welded to at least one electrode end of a spiral electrode group wound in a spiral shape. The present invention relates to an alkaline storage battery and a manufacturing method thereof.

  Alkaline storage batteries such as nickel-cadmium storage batteries and nickel-hydrogen storage batteries have come to be used as batteries for large current applications such as electric vehicles, electric motorcycles, assist bicycles, and electric tools. Alkaline storage batteries used for this type of application are required to have high output characteristics and high energy density. In order to achieve high output characteristics, it is necessary to reduce the resistance of the current collecting component, and it is necessary to close contact between the current collector and the end of the electrode plate. Moreover, since there exists a possibility that a collector may remove | deviate by vibration etc., it is necessary to strengthen the welding strength of a collector and the edge part of an electrode plate.

  In this type of alkaline storage battery, normally, a positive electrode plate and a negative electrode plate are spirally wound through a separator to form a spiral electrode group, and then a negative electrode current collector is disposed at the end of the negative electrode plate of the spiral electrode group. , And a positive electrode current collector is welded to the end of the positive electrode plate to form an electrode body. Next, this electrode body is inserted into a metal outer can also serving as a negative electrode terminal, and the negative electrode current collector is welded to the bottom of the inner surface of the metal outer can, and the lead portion extending from the positive electrode current collector is connected to the positive electrode terminal. After being welded to the bottom of the sealing body that also serves as the sealing member, an electrolytic solution is injected, and the sealing body is attached to the opening of the outer can through an insulating gasket and sealed.

  By the way, when welding the electrode plate end of the spiral electrode group and the current collector, after arranging the current collector on the electrode plate end, the pair of welding electrodes is pushed onto the current collector. By applying a welding current between the pair of welding electrodes, resistance heat is generated to perform welding. In this resistance welding method, a current is passed between the current collector and the electrode plate end of the spiral electrode group, thereby generating resistance heat at the contact portion and welding. Therefore, for efficient resistance welding, it is important to reduce the current that flows on the current collector surface, the so-called reactive current, so that the welding current flows between the current collector and the end of the electrode plate as much as possible. It becomes.

For this reason, for example, Patent Document 1 (Japanese Utility Model Publication No. 55-40970) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2000-315490) propose a technique for reducing such reactive current. became. In this case, Patent Document 1 proposes a technical technique in which contact between the current collector and the electrode plate end portion of the electrode group is performed by a burring protrusion formed on the current collector. On the other hand, Patent Document 2 proposes a technical technique in which a slit is provided in a current collector so that a welding current does not easily pass through the current collector.
By using such a technical method, it has become possible to achieve a certain effect in improving the efficiency of the welding process and improving the welding quality.
Japanese Utility Model Publication No. 55-40970 JP 2000-315490 A

  However, in order to meet the demand for higher capacity in recent years, it is necessary to further improve the welding quality. In particular, it is necessary to use an electrode having a foam core (nickel sponge) as an electrode plate core (electrode substrate). When welding a current collector, it has been strongly required to further improve the welding quality. In this case, for example, in order to improve the welding strength, the welding current may be increased. However, if the welding current is increased, the reactive current also increases in proportion thereto. For this reason, a new problem has arisen that the current collector breaks or blows off.

  Here, when the current collector breaks, the current collection efficiency is lowered, and the operating voltage during discharge is lowered. Further, when explosion occurs, a new problem arises that the explosion is scattered and enters the electrode group, causing a short circuit. In this case, if a small welding current is allowed to flow, the problem that the current collector breaks or blows off is less likely to occur, but conversely, the welding becomes insufficient and the required welding There also arises a problem that the strength cannot be obtained.

  Accordingly, the present invention has been made to solve the above-described problems, and reduces the reactive current flowing in the current collector so that the current collector is not broken or blown out easily. In addition to preventing the occurrence of a short circuit in the electrode group, the welding current at the contact portion between the current collector and the electrode plate end of the electrode group can be increased, so that the electrode of the current collector and the electrode group can be increased. It is an object of the present invention to provide an alkaline storage battery having improved weld strength with a plate end and improved reliability.

The alkaline storage battery of the present invention includes an electrode body in which a current collector is welded to at least one electrode end of a spiral electrode group wound in a spiral shape. And in order to solve the said subject, the electroconductive thin film is interposed between an electrode edge part and an electrical power collector, and the said electrode edge part and the said electrical power collector are welded, It is characterized by the above-mentioned.
As described above, when the electrode end portion and the current collector are welded with the conductive thin film interposed, the welding current easily flows toward the electrode group. As a result, the reactive current flowing on the surface of the current collector can be greatly reduced during welding of the current collector. As a result, even if a large welding current is passed, no explosion or breakage occurs, so that the welding strength with the current collector is improved and the welding quality is stabilized. In addition, since the welding strength with the current collector can be increased, the internal resistance can be reduced, and an alkaline storage battery having excellent discharge characteristics in a large current discharge or the like can be obtained.

  In this case, when the conductive thin film is formed in a circular shape larger than the diameter of the current collector in the portion in contact with the electrode end, it can be electrically connected to almost all surfaces in the portion in contact with the electrode end. Thus, current can be collected from electrodes in a wider range of the spiral electrode group. Thereby, the current distribution from the positive electrode plate or the negative electrode plate becomes uniform, the internal resistance between the current collector and the electrode body decreases, the current collection efficiency increases, and the discharge characteristics improve. In addition, in the part which contact | connects the electrode edge part of an electrical power collector, it arrange | positioned around the center opening arrange | positioned in a center part, a pair of slit arrange | positioned in the symmetrical position with respect to this opening, and a center opening It is desirable that a large number of burring holes are formed. This is because by forming the slit, no current flows through the slit portion, so that the reactive current is reduced. Moreover, it is because a strong welding part will be formed when many burring holes are formed.

  And, in order to weld the electrode end and the current collector by interposing a conductive thin film having excellent conductivity between the electrode end and the current collector, A conductive thin film placement step for placing a conductive thin film between the electrode and the current collector, a current collector placement step for placing a current collector on the conductive thin film, and a current collector What is necessary is just to provide a welding process which arrange | positions a pair of welding electrodes, applies a welding current, and welds an electrode edge part and the said collector.

  In the present invention, the electrode end and the current collector are welded with the conductive thin film interposed therebetween, so that the welding current easily flows in the direction of the electrode group, and the reactive current flows on the surface of the current collector. Can be significantly reduced, and even if a large welding current is passed, explosion and breakage can be prevented. As a result, the welding strength with the current collector is improved, the welding quality is stabilized, the internal resistance can be reduced, and an alkaline storage battery having excellent discharge characteristics such as a large current discharge can be provided.

Hereinafter, an embodiment in which the present invention is applied to a nickel-cadmium storage battery will be described with reference to FIGS. 1 to 5, but the present invention is not limited to this and the scope does not change the gist thereof. And can be implemented with appropriate changes.
FIG. 1 is a perspective view schematically showing components of the electrode body of the present invention. FIG. 2 is a front view schematically showing the conductive thin film of the present invention. FIG. 3 is a diagram schematically showing a positive electrode current collector, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a cross-sectional view showing an AA cross section of FIG. 3 (a). . 4 is a diagram schematically showing a state in which the positive electrode current collector is welded to the electrode group, FIG. 4 (a) is a perspective view showing a pair of welding electrodes, and FIG. 4 (b) is a positive electrode current collector. FIG. 4C is a top view schematically showing a state in which the pair of welding electrodes shown in FIG. 4A is arranged on the top, and FIG. 4C schematically shows the state of the side surface of the main part of FIG. FIG. FIG. 5 is a cross-sectional view schematically showing a nickel-cadmium storage battery of the present invention.

1. Component of electrode body (1) Nickel positive electrode plate The nickel positive electrode plate 11 is a positive electrode active material 11b mainly composed of nickel hydroxide filled in an electrode plate core 11a, and has a predetermined dimension (for example, a length of 200 mm, The width is 33 mm, and the thickness is 0.5 mm). An active material unfilled portion 11c is formed at the upper end of the nickel positive electrode plate 11 after fabrication, and the positive electrode current collector 15 is later welded to the active material unfilled portion 11c. It becomes. Here, a nickel positive electrode plate α is used as the electrode plate core body 11a, and a sintered substrate in which a sintered body is formed on a punched metal plated with nickel is used as the electrode plate core body 11a. Was a nickel positive electrode plate β.

(2) Cadmium negative electrode plate The cadmium negative electrode plate 12 is coated with a negative electrode active material slurry 12b composed of a negative electrode active material mainly composed of cadmium oxide, a conductive agent, and a binder on both surfaces of an electrode plate core 12a made of punching metal. After drying, it is rolled to a predetermined thickness (for example, 0.6 mm), and then cut to a predetermined dimension (for example, a length of 240 mm and a width of 33 mm). . Note that an active material unfilled portion 12c is formed after the lower end portion of the cadmium negative electrode plate 12 after fabrication, and the negative electrode current collector 14 is welded to the active material unfilled portion 12c later. It becomes.

(3) Spiral electrode group Between these nickel positive electrode plates 11 (α, β) and the cadmium negative electrode plate 12, a separator (for example, having a width of 34 mm) 13 made of polypropylene non-woven fabric is interposed to form a spiral shape. Is wound into a spiral electrode group 10a. In this case, as shown in FIG. 1, the active material unfilled portion 11 c of the nickel positive electrode plate 11 (α, β) protrudes from the upper end portion of the separator 13, and the active material unfilled portion 12 c of the cadmium negative electrode plate 12 After being laminated and arranged so as to protrude from the lower end, it is wound in a spiral shape.

  In the upper part of the spiral electrode group 10a thus manufactured, the active material unfilled portion 11c of the nickel positive electrode plate 11 is exposed, and the active material uncoated portion 12c of the cadmium negative electrode plate 12 is exposed below the upper portion. Will be. The spiral electrode group 10a has a space formed by removing the core shaft, and a negative electrode current collector 14 to be described later welded to the negative electrode side end portion is provided in an outer can 17. A welding electrode for welding to the inner surface side bottom of (see FIG. 5) can be inserted.

(4) Negative electrode current collector As shown in FIG. 1, the negative electrode current collector 14 includes a main body portion 14a having a circular planar shape (for example, a diameter of 17.5 mm). A large number of apertures 14b and a pair of slits 14c are formed. Here, a large number of apertures 14b are formed by burring, and a protruding edge (see FIG. 3B) is formed on the periphery of the aperture 14b so as to protrude upward from below in the figure. The pair of slits 14c is formed so as to divide the circular main body 14a into approximately half. By providing this pair of slits 14c, it becomes possible to reduce the reactive current flowing through the negative electrode current collector 14 during welding.

(5) Positive electrode current collector As shown in FIGS. 1 and 3, the positive electrode current collector 15 includes a main body portion 15a having a substantially circular planar shape (for example, a diameter of 17.5 mm), and a main body portion 15a. The planar shape formed by extending includes a lead portion 15b having a substantially rectangular shape. A central opening (for example, a diameter of 5.3 mm) 15c is formed at the center of the main body 15a, and a number of apertures 15d and a pair of slits 15e are formed around the central opening 15c. Yes.

  The central opening 15c is provided for inserting a negative electrode current collector 14 connected to the negative electrode side end and a welding electrode for welding the bottom of the outer can 17. Also in this case, a large number of apertures 15d are formed by burring, and projecting edges 15f projecting downward from above in the figure are formed on the periphery of the apertures 15d. Further, the pair of slits 15e are formed so as to divide the circular main body portion 15a into approximately half, and the reactive current flowing through the positive electrode current collector 15 during welding can be reduced.

(6) Conductive thin film film As shown in FIGS. 1 and 2, the conductive thin film film 16 has a conductive adhesive material (for example, on both sides of a base material 16a having a thickness of 0.07 mm) made of a nonwoven fabric. 16b, 16b were applied (applied to have a thickness of 0.045 mm), and the electrical resistance was 50Ω / inch ² . Is. The conductive thin film 16 is cut so that the planar shape is circular (for example, the diameter is 18.0 mm), and a central opening (for example, the diameter is 5.3 mm) 16c is formed at the center. In addition, a welding electrode for welding the negative electrode current collector 14 connected to the negative electrode side end and the bottom of the outer can 17 can be inserted. In addition, as the conductive material, metal powder such as gold powder can be used in addition to carbon black. Moreover, metal foil can also be used as a conductive film.

2. Next, an example of producing an electrode body using the spiral electrode group 10a, the negative electrode current collector 14, the positive electrode current collector 15, and the conductive thin film 16 having the above-described configuration will be described below. It will be described in detail.
(1) Example 1
The conductive thin film 16 is attached to the upper end surface of the active material unfilled portion 11c of the nickel positive electrode plate 11 (α) of the spiral electrode group 10a manufactured as described above, and the conductive thin film 16 A positive electrode current collector 15 is attached to the substrate. In this case, the space formed in the central portion of the spiral electrode group 10 a, the central opening 16 c formed in the central portion of the conductive thin film 16, and the central portion of the main body portion 15 a of the positive electrode current collector 15 are formed. These are stuck so as to coincide with the center opening 15c.

  Next, a pair of welding electrodes R1 and R2 (see FIG. 4) are mounted on the main body 15a of the positive electrode current collector 15, respectively. At this time, the pair of welding electrodes R <b> 1 and R <b> 2 are placed so as to face each other with a pair of slits 15 e and 15 e formed in the main body portion 15 a of the positive electrode current collector 15 therebetween. Thereafter, a welding current (2 cycles at 3.0 kA) is applied from a welding power source (60 Hz AC power source) V between the pair of welding electrodes R1, R2. As a result, the protruding edge 15f (see FIG. 3B) formed at the periphery of the opening 15d by burring is resistance-welded to the active material unfilled portion 11c of the nickel positive electrode 11, and the spiral electrode group 10a The positive electrode current collector 15 is welded to the end face.

  On the other hand, the conductive thin film 16 is attached to the lower end surface of the active material unfilled portion 12 c of the cadmium negative electrode plate 12 of the spiral electrode group 10 a, and the negative electrode current collector 14 is attached to the lower side of the conductive thin film 16. To wear. Also in this case, these are pasted so that the space part formed in the center part of the spiral electrode group 10a and the center opening 16c formed in the center part of the conductive thin film 16 coincide. Then, after making the pair of welding electrodes R1, R2 contact the negative electrode current collector 14 in the same manner as described above, a welding current (3. (1 cycle at 0 kA) is applied, and the contact portion between the active material uncoated portion 12 c of the cadmium negative electrode plate 12 and the negative electrode current collector 14 is resistance welded. Thereby, the spiral electrode body a1 of Example 1 is produced.

(2) Example 2
The conductive thin film 16 is attached to the upper end surface of the active material unfilled portion 11c of the nickel positive electrode plate 11 (β) of the spiral electrode group 10a produced as described above, and the conductive thin film 16 A positive electrode current collector 15 is attached to the substrate. In this case, the space formed in the central portion of the spiral electrode group 10 a, the central opening 16 c formed in the central portion of the conductive thin film 16, and the central portion of the main body portion 15 a of the positive electrode current collector 15 are formed. These are stuck so as to coincide with the center opening 15c.

  Next, a pair of welding electrodes R1 and R2 (see FIG. 4) are mounted on the main body 15a of the positive electrode current collector 15, respectively. At this time, the pair of welding electrodes R <b> 1 and R <b> 2 are placed so as to face each other with a pair of slits 15 e and 15 e formed in the main body portion 15 a of the positive electrode current collector 15 therebetween. Thereafter, a welding current (one cycle at 3.0 kA) is applied from a welding power source (60 Hz AC power source) V between the pair of welding electrodes R1, R2. As a result, the protruding edge 15f (see FIG. 3B) formed at the periphery of the opening 15d by burring is resistance-welded to the active material unfilled portion 11c of the nickel positive electrode 11, and the spiral electrode group 10a The positive electrode current collector 15 is welded to the end face.

  On the other hand, the conductive thin film 16 is attached to the lower end surface of the active material unfilled portion 12 c of the cadmium negative electrode plate 12 of the spiral electrode group 10 a, and the negative electrode current collector 14 is attached to the lower side of the conductive thin film 16. To wear. Also in this case, these are pasted so that the space part formed in the center part of the spiral electrode group 10a and the center opening 16c formed in the center part of the conductive thin film 16 coincide. Then, after making the pair of welding electrodes R1, R2 contact the negative electrode current collector 14 in the same manner as described above, a welding current (3. (1 cycle at 0 kA) is applied, and the contact portion between the active material uncoated portion 12 c of the cadmium negative electrode plate 12 and the negative electrode current collector 14 is resistance welded. Thereby, the spiral electrode body a2 of Example 2 is produced.

(3) Comparative Example 1
The positive electrode current collector 15 is disposed on the upper end surface of the active material unfilled portion 11c of the nickel positive electrode plate 11 (α) of the spiral electrode group 10a manufactured as described above. In this case, it arrange | positions so that the space part formed in the center part of the spiral electrode group 10a and the center opening 15c formed in the center part of the main-body part 15a of the positive electrode collector 15 may correspond. Next, a pair of welding electrodes R1 and R2 (see FIG. 4) are mounted on the main body 15a of the positive electrode current collector 15, respectively. At this time, the pair of welding electrodes R <b> 1 and R <b> 2 are placed so as to face each other with a pair of slits 15 e and 15 e formed in the main body portion 15 a of the positive electrode current collector 15 therebetween.

  Thereafter, a welding current (2 cycles at 2.0 kA) is applied from a welding power source (60 Hz AC power source) V between the pair of welding electrodes R1, R2. As a result, the protruding edge 15f (see FIG. 3B) formed at the periphery of the opening 15d by burring is resistance-welded to the active material unfilled portion 11c of the nickel positive electrode 11, and the spiral electrode group 10a The positive electrode current collector 15 is welded to the end face. In this case, explosion occurred when attempting to weld with a welding current of 2.0 kA or more, and breaking of the positive electrode current collector 15 occurred when attempting to weld with a welding current of 2.5 kA or more.

  On the other hand, after placing the negative electrode current collector 14 on the lower end of the spiral electrode group 10a and bringing the pair of welding electrodes R1, R2 into contact with the negative electrode current collector 14 in the same manner as described above, A welding current (one cycle at 2.0 kA) is applied from the welding power source (60 Hz AC power source) V between the welding electrodes R1 and R2, and the active material uncoated portion 12c of the cadmium negative electrode plate 12 and the negative electrode current collector 14 Resistance contact welding of Thereby, the spiral electrode body x1 of the comparative example 1 is produced.

(4) Comparative Example 2
The positive electrode current collector 15 is disposed on the upper end surface of the active material unfilled portion 11c of the nickel positive electrode plate 11 (β) of the spiral electrode group 10a manufactured as described above. In this case, it arrange | positions so that the space part formed in the center part of the spiral electrode group 10a and the center opening 15c formed in the center part of the main-body part 15a of the positive electrode collector 15 may correspond. Next, a pair of welding electrodes R1 and R2 (see FIG. 4) are mounted on the main body 15a of the positive electrode current collector 15, respectively. At this time, the pair of welding electrodes R <b> 1 and R <b> 2 are placed so as to face each other with a pair of slits 15 e and 15 e formed in the main body portion 15 a of the positive electrode current collector 15 therebetween.

  Thereafter, a welding current (one cycle at 2.0 kA) is applied from a welding power source (60 Hz AC power source) V between the pair of welding electrodes R1, R2. As a result, the protruding edge 15f (see FIG. 3B) formed at the periphery of the opening 15d by burring is resistance-welded to the active material unfilled portion 11c of the nickel positive electrode 11, and the spiral electrode group 10a The positive electrode current collector 15 is welded to the end face. In this case, explosion occurred when attempting to weld with a welding current of 2.0 kA or more, and breaking of the positive electrode current collector 15 occurred when attempting to weld with a welding current of 3.0 kA or more.

  On the other hand, after placing the negative electrode current collector 14 on the lower end of the spiral electrode group 10a and bringing the pair of welding electrodes R1, R2 into contact with the negative electrode current collector 14 in the same manner as described above, A welding current (one cycle at 2.0 kA) is applied from the welding power source (60 Hz AC power source) V between the welding electrodes R1 and R2, and the active material uncoated portion 12c of the cadmium negative electrode plate 12 and the negative electrode current collector 14 Resistance contact welding of Thereby, the spiral electrode body x2 of Comparative Example 2 is manufactured.

3. Measurement of welding strength Next, two spiral electrode bodies a1, a2, x1 and x2 prepared as described above were prepared, and when these welding strengths were measured, the results shown in Table 1 below were obtained. Obtained. In this case, when measuring the welding strength, the lead portion 15b of the positive electrode current collector 15 of each spiral electrode body a1, a2, x1, x2 is raised vertically to the main body portion 15a, and each electrode body a1, The test was performed by fixing a2, x1, and x2, pulling the lead portion 15b in the vertical direction, and measuring the load until each current collector 15 was detached. In addition, in the welding strength of the following Table 1, average welding strength is shown and those minimum values and maximum values are shown in parentheses.

 As is apparent from the results of Table 1 above, when the electrode body a1 using the nickel positive electrode plate 11 (α) with the foamed nickel as the electrode plate core body 11a is compared with the electrode body x1, the average welding strength of the electrode body x1 is compared. Is 6.9N, the average welding strength of the electrode body a1 is 21.6N, and it can be seen that the electrode body a1 is improved by 14.7N (+ 214%). Further, when the electrode body a2 having the nickel positive electrode plate 11 (β) using the sintered substrate having the punching metal as the electrode plate core body 11a is compared with the electrode body x2, the average welding strength of the electrode body x2 is 56.8N. On the other hand, the average weld strength of the electrode body a2 is 72.5N, and it can be seen that the electrode body a2 is improved by 15.7N (+ 28.7%).

  This is because, in the electrode bodies a1 and a2, the conductive thin film 16 is stuck between the active material unfilled portion 11c of the nickel positive electrode 11 and the positive electrode current collector 15, and therefore the active material unfilled portion 11c. And the contact resistance between the projecting edge 15f formed at the periphery of the opening 15d of the positive electrode current collector 15 is reduced. Thereby, the reactive current flowing through the surface of the positive electrode current collector 15 is reduced, and the welding current flowing through these contact portions is increased. As a result, a large welding current such as 2 cycles at 3.0 kA for the electrode body a1 and 1 cycle at 3.0 kA for the electrode body a2 can flow, and the weld strength of the welded portion is improved. .

4). Nickel-cadmium storage battery Next, an example of manufacturing a nickel-cadmium storage battery using the electrode bodies a2 and x2 manufactured as described above will be described with reference to FIG. First, after the electrode bodies a2 and x2 produced as described above are inserted into the outer can 17, the negative electrode current collector 14 and the bottom of the outer can 17 are welded. Further, a sealing body 18 composed of a positive electrode lid 18 a and a positive electrode cap 18 b is prepared, and a lead portion 15 b extending from the positive electrode current collector 15 is welded to the bottom of the positive electrode lid 18 a provided on the sealing body 18. A valve body 18c and a spring 18d for urging the valve body 18c are disposed in the sealing body 18 composed of the positive electrode lid 18a and the positive electrode cap 18b.

  Next, after the ring-shaped spacer 19a is disposed on the upper outer peripheral portion of the electrode bodies a2 and x2, the upper outer peripheral surface of the outer can 17 is grooved to form the annular groove portion 17a. Thereafter, an electrolytic solution (for example, 30 mass% potassium hydroxide (KOH) aqueous solution) is injected into the metal outer can 17, and the sealing gasket 19 a attached to the outer periphery of the sealing body 18 is attached to the outer can 17. The nickel-cadmium storage batteries A2 and X2 are each assembled by placing on the annular groove portion 17a and crimping and sealing the distal end portion 17b of the outer can 17 to the sealing body 18 side. Here, a battery using the electrode body a2 is referred to as a battery A2, and a battery using the electrode body x2 is referred to as a battery X2. The battery capacities of these batteries A2 and X2 are 2.5 Ah.

5. Battery characteristic test Next, a battery characteristic test was performed using the nickel-cadmium storage batteries A2 and X2 produced as described above. In this battery characteristic test, two of each of these batteries A2 and X2 were used.
(Activation process)
First, each of the batteries A2 and X2 was charged for 16 hours at a charging current of 250 mA in a temperature atmosphere of 25 ° C. Thereafter, the battery was left for 1 hour, discharged at a current of 500 mA until the voltage of each battery A2, X2 became 1.0 V, and an activation process was performed.

(Discharge capacity and discharge operating voltage)
Next, after the activation treatment was performed as described above, the discharge capacity and the discharge operating voltage were measured as follows.
In this case, first, in a temperature atmosphere of 25 ° C., the batteries A2 and X2 were subjected to a so-called −ΔV charging with a charging current of 2.5 A (the charging was stopped when the battery voltage decreased by 10 mV from the maximum value). . Thereafter, the battery was left for 1 hour and discharged at a current value of 40 A until the battery voltage reached 0.8V. The capacity when discharging at 40 A was defined as the discharge capacity, and the discharge voltage at half the time until the discharge was completed was defined as the discharge operating voltage. In addition, in the discharge capacity | capacitance of following Table 2, an average discharge capacity | capacitance (mAh) is shown, and those minimum values and maximum values are shown in the parenthesis.

  As apparent from the results in Table 2, the active material unfilled portion 11c of the nickel positive electrode plate 11 and the positive electrode current collector 15 and the active material unfilled portion 12c and the negative electrode current collector 14 of the cadmium negative electrode plate 12 are shown. When the battery A2 having the electrode body a2 with the conductive thin film 16 attached between the battery X2 and the battery X2 having the electrode body x2 not using the conductive thin film 16 is compared, the average discharge capacity of the battery X2 is 2319 mAh. On the other hand, the average discharge capacity of the battery A2 is 2355 mAh, and it can be seen that the average discharge capacity of the battery A2 is improved by 36 mAh (+ 1.6%).

  The direct current resistance of the battery X2 is 5.96 mΩ, whereas the direct current resistance of the battery A2 is 5.24 mΩ, and the direct current resistance of the battery A2 is 0.72 mΩ (−12.1%). It can be seen that it has only improved. Further, the operating voltage at 40A discharge of the battery X2 is 0.986V, whereas the operating voltage at 40A discharge of the battery A2 is 1.007V, and the operating voltage at 40A discharge of the battery A2 is 21mV. It can be seen that it is improved by (+ 2.1%).

  This is because, in the electrode body a2, the conductive thin film 16 is adhered between the active material unfilled portion 11c of the nickel positive electrode 11 and the positive electrode current collector 15, and the active material of the cadmium negative electrode 12 is not filled. Since the conductive thin film 16 is adhered between the portion 12c and the negative electrode current collector 14, the welding strength between each current collector and each electrode plate end portion is improved, and the internal resistance is reduced. And it is thought that the operating voltage at the time of 40A discharge (at the time of high rate discharge) was improved and the discharge capacity was improved by reducing the internal resistance.

  In the above-described embodiment, between the active material unfilled portion 11 c of the nickel positive electrode 11 and the positive electrode current collector 15 and between the active material unfilled portion 12 c of the cadmium negative electrode 12 and the negative electrode current collector 14. Although the example in which the conductive thin film 16 is interposed is described above, the same effect can be obtained even if the conductive thin film 16 is interposed in at least one of them. Moreover, in embodiment mentioned above, although the example which applies this invention to a nickel cadmium storage battery was demonstrated, even if this invention is applied to alkaline storage batteries, such as a nickel hydride storage battery, besides a nickel cadmium storage battery. It is clear that the same effect can be obtained.

It is a perspective view which shows typically the component of the electrode body of this invention. It is a front view which shows typically the electroconductive thin film of this invention. It is a figure which shows a positive electrode electrical power collector typically, Fig.3 (a) is a top view, FIG.3 (b) is sectional drawing which shows the AA cross section of Fig.3 (a). It is a figure which shows typically the state which welds a positive electrode electrical power collector to an electrode group, Fig.4 (a) is a perspective view which shows a pair of welding electrode, FIG.4 (b) is on a positive electrode electrical power collector. 4A is a top view schematically showing a state in which the pair of welding electrodes shown in FIG. 4A is arranged, and FIG. 4C is a side view schematically showing the state of the side surface of the main part of FIG. It is. It is sectional drawing which shows typically the nickel-cadmium storage battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10a ... Spiral electrode group, 11 ... Nickel positive electrode plate, 11a ... Electrode plate core, 11b ... Positive electrode active material slurry, 11c ... Active material unfilled part, 12 ... Cadmium negative electrode plate, 12a ... Electrode plate core, 12b ... Negative electrode active material slurry, 12c ... Active material unfilled part, 13 ... Separator, 14 ... Negative electrode current collector, 14a ... Main body part, 14b ... Opening, 14c ... Slit, 15 ... Positive electrode current collector, 15a ... Main body part, 15b ... lead portion, 15c ... center opening, 15d ... opening, 15e ... slit, 15f ... edge, 16 ... conductive thin film, 16a ... base material made of carbon film, 16b ... adhesive material, 16c ... center opening, 17 ... outer can, 17a ... annular groove, 17b ... tip, 18 ... sealing body, 18a ... positive electrode lid, 18b ... positive electrode cap, 18c ... valve body, 18d ... spring, 19a ... spacer, 19a ... Mouth gasket

Claims (4)

An alkaline storage battery comprising an electrode body in which a current collector is welded to at least one electrode end of a spiral electrode group wound in a spiral shape,
An alkaline storage battery, wherein the electrode end and the current collector are welded with a conductive thin film interposed between the electrode end and the current collector.   2. The alkaline storage battery according to claim 1, wherein the conductive thin film is formed in a circular shape larger than a diameter of the current collector at a portion in contact with the electrode end portion.   A portion of the current collector that is in contact with the electrode end portion is disposed around a central opening disposed at a central portion, a pair of slits disposed at symmetrical positions with respect to the opening, and the central opening. 3. The alkaline storage battery according to claim 1, wherein a large number of burring holes are formed. A method for producing an alkaline storage battery comprising an electrode body in which a current collector is welded to at least one electrode end of a spiral electrode group wound in a spiral shape,
A conductive thin film film disposing step of disposing a conductive thin film between the electrode end and the current collector;
A current collector arranging step of arranging the current collector on the conductive thin film; and
A manufacturing process for an alkaline storage battery comprising: a welding step of arranging a pair of welding electrodes on the current collector and applying a welding current to weld the electrode end and the current collector. Method.

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