JP5016236B2 - battery - Google Patents

Description

  The present invention relates to a battery, and more particularly to a structure of a lead connecting a current collector plate and a lid.

  In recent years, there has been a rapid increase in the number of electric devices that are required to be compact and lightweight, such as mobile electronic devices such as mobile computers and digital cameras, and cylindrical batteries are used as power sources for these devices. In addition, the demand for batteries is expanding as a power source in a field where a high output characteristic and a long life characteristic are required, such as a power source for a hybrid electric vehicle (HEV), a power tool or a toy.

  As shown in FIG. 10, the conventional battery includes a pole group 25 in which a long positive electrode plate 22 and a negative electrode plate 23 are wound in a spiral shape via a separator 24, and a bottomed cylindrical outer can that accommodates the electrode group 25. 26 and a lid 27 having a gas discharge valve for sealing the opening of the outer can.

  In order to collect the positive electrode and the negative electrode, unfilled portions 28 and 29 that are not filled with an active material are provided at one end in the longitudinal direction of the respective electrode plates, and these unfilled portions are arranged so as not to face each other. The pole group is wound. A substantially circular positive electrode current collector plate 30 and negative electrode current collector plate 31 are welded to these unfilled portions protruding from both ends of the pole group, respectively, and then the positive electrode current collector plate and the lower surface of the lid portion are connected by a current collector lead 21. As a result, electrical connection of each electrode plate is achieved, and current is collected from the entire circumference of the wound electrode group to ensure battery output.

  A lead 21 shown in FIG. 11 has been proposed as means for electrically connecting the lid 27 to the positive electrode current collector plate 30 in a conventional battery. The lower end 21b of the lead 21 is joined to the positive current collector plate 30 and the protrusion 21c formed on the upper end 21a of the lead 21 is joined to the lid 27, whereby the lid 27 is electrically connected to the positive current collector plate 30 via the lead 21. Can be connected.

  When such a battery is used for charging / discharging with a large current, among the battery components, the electrical resistance of the lead connecting the current collector plate connected to the electrode group and the lid is battery characteristics. Has been shown to have a significant impact on In these applications, it is necessary to reduce the internal resistance as much as possible, and various techniques have been studied.

  As a technique for reducing the internal resistance, a method of increasing the cross-sectional area of the battery lead or increasing the number of leads can be considered. However, since the internal resistance cannot be lowered to a sufficient level for the following reasons, such a method is not practical. When the method of increasing the cross-sectional area is adopted, there is a problem that welding becomes difficult because the reactive current increases as the area increases. In addition, as the area increases, the strength of the lead increases and the flexibility decreases, which makes it difficult to fold the lead and decreases productivity, and when the lead is bent, the welding is disconnected. There is a problem that the possibility of causing an internal short circuit by pressing the pole group is increased. Further, when the method of increasing the number is adopted, the number of parts increases as the number increases, so that the assembly becomes complicated.

In addition, as a technique for reducing the internal resistance, “a positive electrode plate and a negative electrode plate wound in a state where a separator is sandwiched between both electrode plates, a case that can accommodate this electrode body, and the electrode body In the cylindrical battery comprising a current collector connected to one of the electrode plates, the current collector is a current collector main body addressed over substantially the entire end face of the electrode body, and the current collector main body The invention of a "cylindrical battery characterized by comprising lead piece portions extending from a plurality of locations at substantially equal angular intervals on the outer peripheral edge of the portion" is known (Patent Document 1, Claim 1).
According to the invention of Patent Document 1, since a plurality of lead pieces are provided, “the current flows evenly from the current collector body through a plurality of parallel circuits, and current concentration and resistance loss are minimized. The effect of “can be suppressed” is obtained.

  However, the invention of Patent Document 1 has the following problems because the lead and the current collecting plate are integrated. First, when the lead is bent upward, the current collector plate is deformed. This deformation increases the defect rate when the current collector plate and the pole group are welded. Next, as the cross-sectional area or the number of leads increases, the facing area between the current collector plate and the pole group decreases. This is because the peripheral edge of the current collector plate is also bent when the lead is bent upward. Furthermore, since the lead position is at the peripheral edge of the current collector plate, the current distribution becomes non-uniform.

  As a technology related to Patent Document 1, “in a cylindrical battery can (1), a separator (42) is interposed between a strip-like positive electrode (41) and a negative electrode (43), respectively, and these are spirally formed. The take-up electrode body (4) wound around is accommodated, and each of the positive electrode (41) and the negative electrode (43) is configured by applying an active material to the surface of the belt-like core body, and the take-up electrode body (4) In the cylindrical secondary battery capable of taking out the electric power generated by the pair of electrode terminal portions to the outside, at least one end of the take-up electrode body (4) has a positive electrode (41) or a negative electrode (43 The edge (48) of the belt-shaped core body constituting the projection protrudes, and the current collector plate (5) is installed to cover the edge (48). The current collector plate (5) is at least a part of the outer peripheral edge. A flat plate-like main body (51) having an arc shape, and the arc-shaped outside of the main body (51) A strip-shaped lead plate (55) protruding from the edge, and the lead plate (55) is provided with a plurality of cuts (57) extending in a direction away from the main body (51). (57) has a proximal end at or near the arcuate outer periphery of the main body (51), and the distal end of the lead plate (55) is connected to one of the electrode terminal portions. The invention of “cylindrical secondary battery” is known (Patent Document 2, Claim 1).

  According to the invention of Patent Document 2, since the lead plate is divided into a plurality of lead portions by a plurality of cuts, the lead portions can be bent individually from the base end positions of the cuts. The lead plate is bent along the arcuate outer periphery of the main body for each lead portion. Therefore, the problem that the facing area between the current collector plate and the pole group, which is a problem in Patent Document 1, is somewhat improved.

However, as in the case of Patent Document 1, since the lead and the current collector plate are integrated in the invention of Patent Document 2, the problem of deformation of the current collector plate that occurs when the lead is bent and the peripheral portion of the current collector plate The problem of non-uniform current distribution due to current collection is unavoidable. Further, when the lead plate is arranged only in a part of the periphery of the current collector plate as in the embodiment of Patent Document 2, the current from the other part concentrates on this part, so that the entire circumference of the current collector plate The internal resistance tends to be higher than when collecting current uniformly, and the effect of lowering the resistance by collecting current from the entire circumference of the electrode group cannot be expected. “A battery case having an opening that also serves as a terminal of one electrode, a sealing body that also serves as a terminal of the other electrode that seals the opening, and at least one end of positive and negative electrodes accommodated in the battery case A storage battery including an electrode body to which a current collector is connected, wherein the sealing body and the current collector are welded to a lead portion made of a cylindrical body having a hollow portion. The storage battery "is known (Patent Document 3, Claim 1).

  As in the invention of Patent Document 3, when the sealing body and the current collector are welded to the lead portion made of the cylindrical body 6 having a hollow portion, the current path during energization is on the peripheral side wall of the cylindrical body. Since the current flows from the current collector to the sealing body in two separate paths, the current collection distance of the lead part becomes the semicircular shape of the cylindrical body, and the voltage drop at the lead part can be reduced by half. become.

However, in order to weld and attach such a lead to the lid and the current collector plate, a welding current is passed between the battery case and the sealing body, and the lead portion is either the sealing body or the current collector. There is a problem that it is necessary to carry out a “welding process for welding” (paragraph 0013), and expensive welding equipment is required to carry out such a welding process. Further, as a characteristic phenomenon when the lead is welded in this welding process, there is a phenomenon that the force with which the lead is pressed against the object to be welded decreases as the welding current increases. This phenomenon is caused by the lead being heated and softened by the current during welding. For this reason, when the welding process is performed with a large current in order to realize a design for increasing the number of welding points, there is a problem that the reliability of welding is lowered and the variation in welding is large. Therefore, with the technique described in Patent Document 3, it is difficult to implement a design in which the number of welding points is increased to reduce the resistance. Such a problem is also recognized in the invention of Patent Document 4.
JP 11-297301 A JP 2004-273288 A JP 2001-143684 A Japanese Patent Laid-Open No. 2004-235036

  As described above, in a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape are connected by leads, there is a technique for reducing internal resistance to a sufficiently low level. There wasn't. Therefore, in the conventional technology, a battery suitable for the purpose of charging / discharging with a large current cannot be obtained. Accordingly, an object of the present invention is to provide a battery having a greatly reduced internal resistance.

  As a result of intensive studies, the present inventors have found that voltage loss can be minimized with inexpensive equipment and inexpensive material cost by making the shape of the lead specific, and the present invention has been completed.

The present invention employs the following means in order to solve the above problems.
(1) In a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape are connected by a lead, the lead is composed of an annular portion and a plurality of strip portions, The annular part is connected to the lid, the strip part has one end connected to the annular part and the other end connected to the current collector plate, and the lead has a comb-like development. A battery characterized by.

(2) In a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape are connected by a lead, the lead includes an annular portion and a plurality of strip portions, The annular part is connected to a current collector plate, the strip part has one end connected to the annular part and the other end connected to a lid, and the lead has a comb-like development. A battery characterized by.

  (3) The battery, wherein the strip portion of the lead is bent at at least three locations.

According to the present invention, since the electrical resistance of the path from the current collector plate connected to the lead to the lid can be greatly reduced, it is possible to provide a battery having a significantly lower internal resistance than the conventional one. . Therefore, this battery is suitable for applications that charge and discharge with a large current. Moreover, this battery can be manufactured with inexpensive equipment. Furthermore, according to the present invention, it is possible to provide a battery having a small electrical resistance in the path from the current collector plate to the lid at a low material cost.

The inventors of the present invention have confirmed that the resistance between the lid and the positive electrode current collector plate occupies a large portion of the battery resistance by analyzing the resistance component of the sealed battery. Therefore, as a result of various studies to reduce the connection resistance between the lid and the positive electrode current collector plate, the present inventors have found that the number of welding points as well as the length and cross-sectional area of the current collection path of the lead are extremely important factors. As a result, the present inventors have found a battery using a lead having a specific shape according to the present invention. Furthermore, as a result of studying to increase the number of welding points, the present inventors have found that the battery of the present invention having at least four and not more than eight current collecting paths connecting the lid and the positive electrode current collector plate has an extremely low resistance. It was clarified that the lid and the positive electrode current collector were connected. Furthermore, the present inventors realized an inexpensive material cost by configuring the current collecting paths from a single plate, and the junction between the current collecting path and the lid or the current collecting path and the positive current collecting plate. It was found that the lid and the positive electrode current collector plate can be connected with extremely low resistance by setting the number of welding points in the joint portion to a plurality of points per joint portion. In addition, said current collection path | route means the path | route through which the electric current from a current collection board to a lid | cover passes.

  The lead used in the battery of the present invention is composed of an annular portion and a plurality of strip portions, the annular portion is connected to a lid, and one end of the strip portion is connected to the annular portion. The end is connected to the current collector plate. This lead will be described with reference to the drawings. FIG. 1 is a developed view of an example of a lead used in the present invention, in which Ni or FeNi (nickel plated steel plate) having a thickness of 0.2 to 0.4 mm is punched or processed by wire cutting. This lead is composed of an annular portion 1 and a strip portion 2. As shown in this figure, the annular portion 1 is annular with a through hole 7. A plurality of strip portions 2 are provided, and one end of each strip portion 2 is connected to the annular portion 1. The through hole 7 of the annular portion 1 is for inserting a welding electrode. In this figure, reference numeral 8 denotes a notch, and 9 denotes a protrusion, both of which are for increasing the welding strength. The notch portion 8 is used to ensure welding so that the welding current does not concentrate and the lead does not break.

  In the battery of the present invention, a plurality of current collecting paths between the lid and the positive electrode current collecting plate are formed by using the leads as described above. In this battery, since the total cross-sectional area of the current collecting path is larger than when the conventional lead shown in FIG. 10 is used, the electric resistance between the lid and the positive electrode current collecting plate is low. The strip portion of the lead has a structure that is continuous with the annular portion. Therefore, even if the number of strips is increased and the current collecting paths are increased, the number of parts does not increase. Therefore, it is easier to assemble the battery than when the number of leads is simply increased. Therefore, according to the present invention, the number of current collecting paths between the lid and the positive electrode current collecting plate can be increased to a level that cannot be achieved by the prior art, and as a result, four or more that can achieve low resistance. Eight or less current collecting paths can be implemented. In addition, since the lead has an annular portion, uniform current collection is possible from the entire circumference of the current collector plate. Uniform current collection is obtained when the strips are arranged at equal intervals around the annular part as shown in FIG. The “equal interval” here may naturally include an error, and the upper limit of the error is preferably a length corresponding to the width of the strip portion. By setting the upper limit of the error of the interval length in this way, at least a part of the strip portion is arranged at equal intervals around the annular portion.

  In the battery of the present invention, the number of welding points at the joint between the lead and the lid or the joint between the lead and the positive electrode current collector plate is set to a plurality of points per joint, thereby greatly reducing welding defects and reducing the weld resistance. It can be further reduced. The number of welding points is extremely important for reducing the resistance of the current collecting path, but if only one point is welded per joint, the welding strength is insufficient while using the battery. There is a possibility that the welding point may come off and the resistance may increase, resulting in a decrease in battery life performance. In addition, the above lead can be manufactured by cutting out from a single raw material plate. This method has fewer steps than the method of connecting the annular portion and the strip portion after cutting them from different raw material plates, and can realize an inexpensive material cost.

  As another example of the lead used in the present invention, there is a developed view of FIG. This drawing shows that the developed view of this lead is composed of an annular portion 1 and a plurality of strip portions 2, the annular portion 1 is in a strip shape, and the strip portion 2 is from one long side of the annular portion 1. It extends in one direction, indicating that it is comb-like as a whole. In addition, "comb shape" means the thing of the shape which provided the several clearance gap in the board | plate material like FIG. This lead is used by a method in which the belt-like annular portion 1 is rolled into an annular shape and then stored in a battery. Therefore, the direction in which the strips extend is not limited to the same direction for all the strips, and may be any direction that can contact the current collector plate when stored in the outer can. The state after being rolled into an annular shape is shown in the side view and perspective view of FIG. By rounding the belt-like portion into an annular shape to form the annular portion 1, the current can be collected from the entire collection of pole groups.

  When the lead used in the present invention is housed in a battery, the strip portion 2 of the lead is bent as shown in FIG. Further, the notch 6 at the tip of the strip 2 in this figure is a process for ensuring welding so that the welding current is not concentrated and the lead is not broken. Further, as shown in this figure, the annular portion 1 may be provided with a connection tab 3 in order to securely connect the lid. Two or more connecting tabs 3 are preferably arranged at equal intervals from the viewpoint that the energization path can be distributed over the entire circumference, and particularly preferably arranged at a position facing the annular portion 1 as shown in FIG. Further, the connection tab 3 is preferably provided with a notch as shown in FIG. 2 so that the welding current is not concentrated and the lead is not broken. In addition, in the perspective view of FIG. 3, two connection tabs on the front left and right sides are omitted. That is, only six of the eight tabs are shown.

  As shown in FIG. 4, the lead used in the present invention is connected to the positive electrode current collector plate by resistance welding, the connection tab 3 is welded to the inner surface of the lid, and the strip portion 2 is further folded in a zigzag manner. Folded into a battery and stored inside the battery. After that, the opening of the battery case can be crimped and sealed. By forming the shape to be folded in a zigzag shape, the strip portion 2 can be expanded and contracted in the vertical direction. Therefore, since the space between the lid and the battery case can be secured, the welding electrode 35 can be easily inserted. At this time, it is preferable that the strip portion 2 is bent at least at three places, and in particular, the strip portion 2 is bent at three places, ie, one mountain fold portion 4 and two valley fold portions 5. preferable. By bending in three places in this way, a portion of the strip portion 2 that is welded to the current collector plate can be arranged in parallel to the current collector plate. Therefore, resistance welding of that part can be performed reliably. In addition, “mountain fold” means that the lead 2 is rolled into an annular shape, and then the strip portion 2 is bent so as to be convex toward the center of the ring. It means to bend so that it becomes convex. “Fold in a zigzag” means that the strip 2 is folded in the vertical direction along the fold after the folding process. As described above, the present invention does not require a large-capacity welding apparatus as an apparatus for welding the lead to the lid and the current collector plate.

  As another example of the lead used in the present invention, it is composed of an annular portion and a plurality of strip portions, the annular portion is connected to a current collector plate, and one end of the strip portion is connected to the annular portion. And the other end is connected to a lid. This lead corresponds to, for example, the lead of FIG. 1 or 2 inverted and housed in a battery. That is, when using the lead having the developed view of FIG. 1, after welding the annular portion 1 of this figure to the current collector plate, the strip portion 2 is welded to the lid, and then the strip portion 2 is folded into a zigzag shape. Store inside the battery. When the lead having the development view of FIG. 2 is used upside down, the development view is the same as the case of FIG. 1 except that the belt-like annular portion 1 is rounded and welded to the current collector plate. The internal resistance of the battery when the lead of FIG. 1 or FIG. 2 is used upside down is at the same level because the number of current collecting paths is the same as that when the lead is not upside down.

  As a lead used in the battery of the present invention, a lead having a comb-like development as shown in FIG. 2 is preferable in view of a good material yield as compared with a lead having a radial development as shown in FIG. When the comb shape is cut out from one plate, as shown in FIG. 6A, two leads can be arranged so that the comb teeth are alternately arranged. Therefore, it can be seen that the material yield when cutting the shape from the raw material plate is superior to that of the radial shape as shown in FIG.

  In the present invention, the annular portion or strip portion of the lead may be directly connected to the lid, but may be connected via an auxiliary lead. The “auxiliary lead” has a function of electrically connecting the lid and the lead. The auxiliary lead will be described with reference to FIG. The auxiliary lead is formed by punching or wire cutting Ni or FeNi (nickel plated steel plate) having a thickness of 0.4 to 1.0 mm. (In the example in the figure, a nickel plate having a thickness of 0.4 mm was punched or wire cut.) In the example in this figure, the auxiliary lead body 11 has an octagonal shape and has a connection tab 12 for each side. . In this figure, only one place was developed, and seven places were bent and drawn. By bending the connection tabs 12 at eight positions of the auxiliary lead 10 at right angles, the connection tabs 12 protrude toward the pole group side, and can be welded to the annular portion 1 or the strip portion of the lead. Regarding the connection between the lid and the lead, the auxiliary lead may be attached to the inner surface of the lid in advance for the purpose of facilitating the connection work.

  In order to weld the lid and the lead before sealing the battery of the present invention, it is necessary to have a gap for inserting the welding electrode into the opening end surface of the battery case containing the electrode group and the inner surface of the lid. By adopting a shape that is folded and stored in a zigzag shape, the battery can be sealed after the lead and the inner surface of the lid are welded. In particular, when welding the lead to the inner surface of the lid, it is desirable to attach an auxiliary lead having a generally circumferential connection tab to the inner surface of the lid in advance, which facilitates the resistance welding between the lead and the lid. .

In the battery of the present invention, in order to shorten the current collecting path, when the lead strip portion 2 is made as short as possible, when welding the lid and the positive electrode current collector plate, first, the first auxiliary lead is welded to the lid. It is possible to perform the process and the second process of welding the lead to the positive electrode current collector plate and the third process of welding the connection tab of the auxiliary lead and the lead in this welding order.
In the battery of the present invention, the current collecting path is 4 to 8, the strip portion is bent to provide one mountain fold portion and two valley fold portions, and the joint portion of the lead and the lid or the lead By setting the number of welds at the joint with the positive current collector plate to multiple points per joint, the area of the current collection path between the lid and the positive current collector is increased, and the length of the current collection path is shortened. At the same time, the number of welding points can be made equal to or greater than the number of current collecting paths, so that a battery having excellent output characteristics can be obtained with reduced current resistance of the battery.

  The present invention is not limited to a non-aqueous electrolyte type or an aqueous electrolyte type as long as it is a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator and a negative electrode are wound in a spiral shape are connected by leads. Applicable. Taking a nickel metal hydride battery as an example, a composite hydroxide in which nickel hydroxide, zinc hydroxide and cobalt hydroxide are co-precipitated is used for the nickel electrode of the positive electrode. Furthermore, in the nickel electrode, Y, Er, It is preferable to add a rare earth element such as Yb or a compound thereof to suppress the generation of oxygen at the nickel electrode when the oxygen overvoltage of the nickel electrode is increased and rapid charging is performed.

In addition, for the hydrogen storage alloy electrode of the negative electrode, an alloy generally capable of storing hydrogen and called AB ₂ or AB ₅ is used, but the composition is not particularly limited. Particularly preferably, Co and part of Ni of AB ₅ type MmNi ₅ (Mm is a mixture of rare earth elements), Mn, Al, alloys obtained by substituting Cu or the like, excellent charge-discharge cycle life characteristics and high discharge capacity Since it has, it is preferable. In order to further improve the resistance reduction effect by applying the present invention, it is more preferable to treat the alloy with an alkaline treatment liquid in advance and apply a catalyst to the surface to reduce the reaction resistance of the negative electrode.

  In the following, the present invention will be described in more detail using a nickel metal hydride storage battery as an example, but the present invention is not limited to the following description.

(Preparation of positive electrode plate)
An ammonium complex and an aqueous sodium hydroxide solution were added to an aqueous solution in which nickel sulfate, zinc sulfate and cobalt sulfate were dissolved at a predetermined ratio to form an ammine complex. While vigorously stirring the reaction system, caustic soda is further added dropwise to control the pH of the reaction system to 10 to 12, and the spherical high-density nickel hydroxide particles serving as the core layer base material are converted into nickel hydroxide: zinc hydroxide: cobalt hydroxide. = 93: 5: 2 The weight ratio was synthesized. (Formation of surface layer)
Spherical high-density nickel hydroxide particles serving as the core layer base material were put into an alkaline aqueous solution controlled to pH 10 to 13 with caustic soda. While stirring the solution, an aqueous solution containing cobalt sulfate and ammonia at predetermined concentrations was added dropwise. During this time, an aqueous caustic soda solution was appropriately added dropwise to maintain the pH of the reaction bath in the range of 10-13. The pH was maintained in the range of 10 to 13 for about 1 hour, and a surface layer made of a mixed hydroxide containing Co was formed on the surface of the nickel hydroxide particles. The ratio of the surface layer of the mixed hydroxide was 4 parts by weight in terms of the amount of Co metal with respect to 100 parts by weight of core layer mother particles (hereinafter simply referred to as core layer) containing Co.

(Oxidation treatment of surface layer)
50 g of nickel hydroxide particles having a surface layer made of the mixed hydroxide was put into a 30 wt% (10N) aqueous caustic soda solution at a temperature of 110 ° C. and sufficiently stirred. Subsequently, excess K ₂ S ₂ O ₈ was added to the equivalent of the cobalt hydroxide contained in the surface layer, and it was confirmed that oxygen gas was generated from the particle surface. The active material particles were filtered, washed with water and dried.

(Preparation of positive electrode plate)
A carboxymethyl cellulose (CMC) aqueous solution is added to 100 parts by weight of the cobalt-coated active material particle powder to make a paste of the active material: CMC solute = 99.5: 0.5, and the paste is 450 g / m. No. ² porous body (nickel cermet # 8 manufactured by Sumitomo Electric Co., Ltd.) was filled. Then, after drying at 80 ° C., pressing to a predetermined thickness, coating the surface with polytetrafluoroethylene, 47.5 mm wide (1 mm uncoated part), 1150 mm long, 6500 mAh (6.5 Ah) nickel An electrode plate was used.

(Preparation of negative electrode)
A hydrogen storage alloy having a composition of AB ₅ type rare earth MmNi _3.6 Co _0.6 Al _0.3 Mn _0.35 having a particle diameter of 35 μm was immersed in an alkaline aqueous solution. That is, the hydrogen storage alloy powder after the hydrogen storage treatment was immersed in a 46 wt% NaOH aqueous solution at 20 ° C. and treated at 100 ° C. for 2 hours.

  Thereafter, the mixture was filtered under pressure and washed with water at a pH of 10 or less. Then, diluted acid was added to dissolve rare earth impurities, followed by pressure filtration, and hydrogen desorption with 80 ° C. hot water. Then, after pressure filtration to separate the treatment liquid and the alloy, pure water was added in the same weight as the alloy weight, and 28 kHz ultrasonic waves were applied for 10 minutes. Further, after that, pure water was poured from the lower part of the stirring layer while gently stirring, and the rare earth hydroxide released from the alloy was removed by flowing the waste water. Then, hydrogen desorption was performed by exposing the alloy to 80 ° C. hot water. The hot water is filtered under pressure, washed again with water, the alloy is cooled to 25 ° C., 4% hydrogen peroxide water is added in the same amount as the alloy weight with stirring, hydrogen desorption is performed, and the hydrogen storage alloy for electrodes is obtained. Obtained.

  The obtained alloy and a styrene-butadiene copolymer aqueous solution were mixed at a solid content weight ratio of 99.35: 0.65, dispersed in water to form a paste, and iron was nickel-plated using a blade coater. After being applied to the punched steel plate, dried at 80 ° C., and then pressed to a predetermined thickness to obtain a hydrogen storage alloy negative electrode plate having a width of 47.5 mm and a length of 1750 mm and a capacity of 11000 mAh (11.0 Ah).

(Production of sealed nickel-metal hydride batteries)
The negative electrode plate, a 120 μm-thick polypropylene non-woven separator having a sulfonation treatment, and the positive electrode plate were combined and wound into a roll. A circle having a thickness of 0.4 mm made of a nickel-plated steel plate on the end face of the positive electrode substrate projecting from one winding end face of the wound pole group and a radius of 14.5 mm provided with a circular through hole in the center. Plate-shaped positive electrode current collector plates were joined by resistance welding. A disc-shaped negative electrode current collector plate having a thickness of 0.4 mm made of a steel plate with nickel plating applied to the end face of the negative electrode substrate protruding from the other wound end face of the wound electrode group was joined by resistance welding. Prepare a bottomed cylindrical battery case made of nickel-plated steel plate, and attach the current collector plate to the electrode plate group, the positive current collector plate is the open end side of the battery case, and the negative current collector plate is It accommodated in the battery case so that it might contact | abut to the bottom of a battery case, and the center part of the negative electrode current collecting plate was joined to the bottom wall part of the battery case by resistance welding. Next, a vibration isolating ring was inserted into the upper inner peripheral side of the battery case can, and a groove was formed on the outer peripheral side of the battery case can to form an annular groove at the upper end portion of the vibration isolating ring.

  Prepare a disc-shaped lid made of nickel-plated steel plate with a circular through hole with a diameter of 0.8 mm in the center. A valve body (rubber valve) and a cap (positive electrode terminal) are placed on the outer surface of the lid. Attached. A ring-shaped gasket was attached to the lid so as to squeeze the periphery of the lid.

Next, a 0.2 mm thick nickel plate is processed to produce a development lead as shown in FIG. 2, and the annular portion of the lead is rounded, and then the eight strips are creased. After that, as shown in FIG. 4B, it was placed on the upper surface of the positive electrode current collector plate and welded. The number of welding points was 2 per strip.
At this time, the diameter of the ring formed by the annular portion is preferably 25.9 mm or less in order to prevent interference with the gasket, and in order to allow the connection tab to be welded at the flat portion on the back surface of the lid. It is preferably 6 mm or more and 17 mm or less. The width of the strip portion is preferably set to be equal to or less than the distance between two adjacent strip portions because the strip portion can be efficiently cut out from the raw material plate as shown in FIG. For example, the width of the strip portion in FIG. 2 is preferably 3.98 mm or less when the length of the annular portion is 59.7 mm. Moreover, as a nickel plate, the thing of 0.2 mm or more and 0.3 mm or less can be utilized. If it is less than 0.2 mm, it is easy to break during processing, and if it exceeds 0.3 mm, it becomes difficult to bend, and the length of the portion connected to the current collector plate needs to be made longer than necessary.

Then, after pouring a predetermined amount of an electrolytic solution composed of an aqueous solution containing 6.8 mol / dm ³ of KOH and 0.6 mol / dm ³ of LiOH, the lead connection tab 3 was tilted outwardly of the circumference. .

  Next, the lid was placed on the connection tab of the lead, and the connection tab of the lead and the lid were welded as shown in FIG.

  Thereafter, as shown in FIG. 4 (d), the lead strips are folded in a zigzag shape, the lid is pushed into the battery case, the open end of the battery case is crimped and hermetically sealed, and the D-shaped sealed type A nickel metal hydride battery was produced.

A sealed nickel-metal hydride storage battery was produced in the same manner as in Example 1 except that the number of lead strips was four as shown in FIG. In addition, the number of welding points between the positive electrode current collector plate and the lead in the first welding process was set to 2 for each strip portion.

  As shown in FIG. 8, a battery was manufactured in the same manner as in Example 1 except that a lead without the connection tab 3 was used and an auxiliary lead was used. That is, an auxiliary lead 10 having a nickel plate having a thickness of 0.4 mm and having a shape as shown in FIG. 5 was prepared. A disc-shaped lid made of a nickel-plated steel plate and provided with a circular through hole with a diameter of 0.8 mm in the center is prepared, and the auxiliary lead 10 is brought into contact with the inner surface side of the lid, as shown in FIG. Thus, the 1st welding process of welding auxiliary lead 10 to the inner surface of lid 18 was carried out.

  Next, as shown in FIG. 8, a second welding process was performed in which a nickel plate having a thickness of 0.2 mm was processed and a lead having eight strip portions was welded to the upper surface of the positive electrode current collector plate. The number of welding points was 2 per strip.

  A valve body 90 (rubber valve) and a cap 80 (positive electrode terminal) were attached to the outer surface of the lid 18. A ring-shaped gasket was attached to the lid so as to squeeze the periphery of the lid.

Thereafter, a predetermined amount of an electrolytic solution composed of an aqueous solution containing 6.8 mol / dm ³ of KOH and 0.6 mol / dm ³ of LiOH was injected.

  The lead was attached so as to surround the side of the connection tab 12 of the auxiliary lead attached to the lid, and the annular portion of the lead and the auxiliary lead were welded as shown in FIG.

  After that, as shown in FIG. 9 (d), the lead strip is folded into a zigzag shape, the lid is pushed into the battery case, the open end of the battery case is crimped and hermetically sealed, and the D-shaped sealed type A nickel metal hydride battery was produced.

  In addition, about the negative electrode current collecting plate, the center part was joined to the bottom wall part of the battery case by resistance welding in the same manner as in Example 1.

  In Example 1, a sealed nickel-metal hydride storage battery was manufactured in the same manner as in Example 1 except that the number of welding points between the positive electrode current collector plate and the lead in the first welding step was one per strip. Produced.

  In Example 2, a sealed nickel-metal hydride storage battery was produced in the same manner as in Example 2 except that one of the four strips of the lead as shown in FIG. did. In addition, the number of welding points between the positive electrode current collector plate and the lead was set to 2 for each strip portion.

(Reference Example 6)
A lead having a radial shape as shown in FIG. 1 was prepared by cutting a nickel plate having a thickness of 0.4 mm by wire cutting. The central portion of the lead has a circular shape with a diameter of 18.5 mm and a through hole 7 of 8 mm, and has eight strip portions 2, which extend radially from the annular portion.

  First, similarly to the other examples, the strips of the radial leads were welded by vertically setting the welding electrode on the upper surface of the positive electrode current collector plate. The electrode plate group to which the current collector plate is attached is a bottomed cylinder made of a steel plate nickel-plated so that the positive electrode current collector plate contacts the open end side of the battery case and the negative electrode current collector plate contacts the bottom of the battery case. In a battery case.

A predetermined amount of an electrolytic solution composed of an aqueous solution containing 6.8 mol / dm ³ of KOH and 0.6 mol / dm ³ of LiOH was injected, and then the annular portion of the lead and the lid were welded.

  Thereafter, the strip portion was folded and the lid was pushed into the battery case can, and the open end of the battery case was crimped and hermetically sealed to produce a D-shaped sealed nickel-metal hydride battery. In addition, about the negative electrode current collecting plate, the center part was joined to the bottom wall part of the battery case by resistance welding in the same manner as in Example 1.

(Comparative Example 1)
As the positive electrode current collector integrated lead described in Patent Document 1, a punched lead plate as shown in FIG. 12 was applied. The lead plate was made of a nickel plate having a thickness of 0.4 mm, and a battery was prepared using a lid provided with auxiliary leads in exactly the same manner as in Example 3 except that this current collector integrated lead was used. .

  In addition, the number of welding points between the lead piece and the side surface of the auxiliary lead connection tab was two points per lead piece.

(Chemical formation)
The sealed storage battery is left at ambient temperature of 40 ° C. for 12 hours, charged at 130 mA (0.02 CA) at 1200 mAh, then charged at 650 mA (0.1 CA) for 10 hours, and then 1V at 1300 mA (0.2 CA). Discharged until. Further, after charging at 650 mA (0.1 CA) for 16 hours, the battery was discharged to 1 V at 1300 mA (0.2 CA), and charging / discharging was performed as 4 cycles for 1 cycle. After the completion of the fourth cycle discharge, the internal resistance was measured using 1 kHz alternating current.

(Measurement of output density)
The measurement method of the output density is the 10th second voltage at the time of 60A discharge when the 10th second voltage is discharged at 60A for 12 seconds after charging at 650mA (0.1CA) for 5 hours from the end of discharge in a 25 ° C atmosphere. After charging the electrical capacity for discharge at 6 A, the voltage at 10 seconds when discharging at 90 A for 12 seconds is the voltage at 10 seconds when discharging at 90 A, and after charging the electrical capacity for discharge at 6 A, 12 seconds at 120 A The 10th voltage at the time of discharging is set to the 10th voltage at the time of 120A discharge, the electric capacity of the discharge is charged at 6A, and then the 10th voltage at the time of flowing at 150A for 12 seconds is the 10th voltage at the time of 150A discharge. Then, after charging the electrical capacity for discharge at 6A, the voltage at the 10th second when flowing at 180A for 12 seconds was the voltage at the 10th second at 180A discharge. Each 10-second voltage was linearly approximated with a current value and a voltage value by the method of least squares. The voltage value at a current value of 0A was E0, and the slope was RDC. After that, the output density (W / kg) = (E0−0.8) ÷ RDC × 0.8 ÷ battery weight (kg) was applied to obtain the output density in the 25 ° C. battery at 0.8V cut.

The batteries obtained in Examples 1 to 5, Reference Example 6 and Comparative Example 1 were formed under the above-described conditions, and the internal resistance and output density were measured. The results are shown in Table 1.

Table 1 also shows the area required to make two leads as numerical values for evaluating the yield when cutting the leads used in each battery from the raw material plate. When cutting out, they were arranged as shown in FIG.

As can be seen from the results of the batteries of Example 1, Example 2, Example 3 and Reference Example 6 in Table 1, the number of strips of the leads is 4 or more and 8 or less, that is, the current collection path is 4 paths or more and 8 paths. In the following cases, a battery that uses a lead composed of a single plate and has a plurality of welding points between the lead and the lid or the lead and the positive electrode current collector plate per path has an internal resistance of 1 It was found that the output density was as low as 1 mΩ or less, and the output density was as high as 1300 W / kg or more. The values of the internal resistances of these examples greatly exceeded the values of the comparative examples.

Furthermore, in the batteries of Example 1, Example 3 and Reference Example 6 which have 8 paths and the number of welding points between the positive electrode current collector plate and the lead is 16, it can be seen that the output exceeds 1400 W / kg. . Maintaining an output of 1400 W / kg or more retains the performance of not cutting a 1 V cell at room temperature even when discharging at 200 A (equivalent to a rate of 30 CA) when assisting in a hybrid electric vehicle (HEV). It means that. For this reason, a nickel metal hydride battery having a power density of 1400 W / kg or more can set 1 V / cell as the lower limit value of voltage control for preventing overdischarge. The discharge pattern is also preferable because overdischarge can be prevented.

  This indicates that not only the cross-sectional area and length of the current collecting path but also the number of welding points for each path is important for reducing the battery internal resistance.

  On the other hand, the power density of the battery of Comparative Example 1 did not reach 1400 W / kg. This is thought to be due to the fact that the current distribution is non-uniform due to the fact that the peripheral portion of the current collector plate is bent together with the lead in addition to the lead being located at the outermost periphery of the current collector plate. .

  By attaching the auxiliary lead to the inner surface of the lid in advance as in Example 3, the connection between the lead and the lid can be welded from the side via the auxiliary lead as shown in FIG. Welding work can be easily performed while checking the welding location.

  Further, in the battery configuration of the present invention, when the strip part is folded at one place or two places, the probability of occurrence of a defect in which the welding point is removed when the lead is folded is compared with the case of three places. it was high.

  The reason why the internal resistance of the battery of Example 4 was higher than others could be that defective welding occurred because there was only one welding point per strip.

  Further, in the case of the integrated lead of Comparative Example 1, as described above, after welding to the positive electrode melting end surface, when the lead piece is bent and raised, and after the lead piece and the lid are connected by welding via the auxiliary lead, the lid When the battery was pushed into the battery case, a large amount of defects occurred due to the weld point between the lead and the positive electrode coming off.

When the development is a radial lead as in Reference Example 6, except for the yield performance when the lead is cut out from the raw material plate, the number of welding points is simultaneously reduced while shortening the current collection path length as in Example 1. Since the number of current collecting paths can be made equal to or greater than the number of current collecting paths, it is possible to obtain a battery having reduced output current resistance and excellent output characteristics.

The yield when cutting the lead from the raw material plate is clear from the results in Table 1.
That is, as used in Example 1, developed view comb-shaped lead, can be arranged so that the two leads each other comb alternating as shown in Figure 6, the reference example 6 It can be seen that the yield is better than the radial one. From this point, it can be seen that the comb-shaped lead having a developed view is superior in material yield and industrially extremely superior to those having a radial developed view.

  Further, in the above-described embodiment, the example in which the auxiliary lead as shown in FIG. 5 is attached to the inner surface of the lid in advance and the lead is welded to the side surface to produce the battery has been described. If a connecting surface for welding is provided, the same effect can be obtained even if the shape is not the one shown in FIG.

It is a figure which shows the expanded view of the lead concerning a reference example. It is a figure which shows the expanded view of the lead concerning one Example of this invention. It is a figure which shows the structure of the lead concerning one Example of this invention. It is a model figure which shows the manufacturing process of the cylindrical battery concerning one Example of this invention. It is a figure which shows the structure of the auxiliary lead used by this invention. It is a figure which shows the expanded view of the lead concerning one Example of this invention. It is a figure which shows the expanded view of the lead concerning one Example of this invention. It is a figure which shows the expansion | deployment figure and structure of a lead concerning one Example of this invention. It is a model figure which shows the manufacturing process of the cylindrical sealed type concerning one Example of this invention. It is sectional drawing which shows the structure of the conventional cylindrical battery. It is a figure which shows the structure of the lead | read | reed of the conventional cylindrical battery. It is a figure which shows the expanded view of the member which integrated the lead concerning the comparative example, and the current collecting plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ring part 2 in a lead 2 Strip part 3 in a lead 4 Connection tab 4 in a lead 4 Mountain fold part 5 Valley fold part 6 Notch part 7 provided in the strip part Through hole 8 Notch part 9 provided in the annular part Projection 10 Auxiliary Lead 11 Auxiliary lead body 12 Connection tab 21 in auxiliary lead 22 Lead in conventional battery 22 Positive electrode plate 23 Negative electrode plate 24 Separator 25 Electrode group 26 Outer can 27 Lid 28 Active material unfilled portion 29 in positive electrode plate Active material in negative electrode plate Unfilled portion 30 Positive electrode current collector 31 Gasket 35 Welding electrode 80 Cap 90 Valve body

Claims (3)

In a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator and a negative electrode are wound in a spiral shape are connected by leads, the lead is composed of an annular portion and a plurality of strip portions, and the annular portion is , Connected to the lid, the strip portion, one end is connected to the annular portion and the other end is connected to the current collector plate ,
The battery is characterized in that the development of the lead is comb-shaped . In a battery in which a current collector plate and a lid welded to a pole group in which a positive electrode, a separator and a negative electrode are wound in a spiral shape are connected by leads, the lead is composed of an annular portion and a plurality of strip portions, and the annular portion is The strip is connected to the current collector plate, one end of which is connected to the annular portion and the other end is connected to the lid ,
The battery is characterized in that the development of the lead is comb-shaped . The battery according to claim 1, wherein the strip portion of the lead is bent at at least three locations.