JP2008135374A - Sealed secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed secondary battery with stabilized characteristics of each electrode group and having high reliability, in one with a plurality of electrode groups stored in a battery case. <P>SOLUTION: The battery case 10 is provided with a plurality of cylindrical housing parts 12a to 12d for housing a plurality of electrode groups 20, respectively, and communication parts 13a to 13c coupling with housing parts 12a to 12d adjoining each other. Inner peripheries of the housing parts 12a to 12d have substantially the same shape as outer peripheries of the electrode groups 20, and the communication parts 13a to 13c are formed along side faces of the housing parts 12a to 12d. The electrode groups 20 have cylindrical shapes each formed by winding a cathode plate 21 and an anode plate 22 through a separator 23 and are stored in the housing parts 12a to 12d, respectively, without substantially any gaps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-capacity sealed secondary battery such as a driving power source and a backup power source.

  Nickel metal hydride storage batteries and nickel cadmium storage batteries are examples of sealed secondary batteries. Among them, non-aqueous electrolyte secondary batteries represented by lithium ion batteries are lightweight, small, and have high energy density. It is used in various applications, from consumer devices such as electric vehicles to power sources for electric vehicles and power tools and backup power sources. In particular, in recent years, non-aqueous electrolyte secondary batteries have attracted attention as drive power sources and backup power sources, and development toward higher capacities has become active.

  In order to increase the battery capacity, for example, it is conceivable to increase the number of times of winding of the positive electrode and the negative electrode wound through the separator to increase the electrode area of the electrode group, but as the number of times of winding increases. As a result, there is a problem in that the heat dissipation is deteriorated, and as a result, the battery life is reduced due to non-uniform temperature in the battery. In addition, when the number of windings is increased, problems such as winding deviation occur, and there are many problems in manufacturing.

  As a method for solving such a problem associated with an increase in the size of a battery, Patent Document 1 discloses a method in which an electrode group is separated into a plurality of small electrode groups and accommodated in a container.

  FIG. 10 is a perspective view showing the configuration of the battery case described in Patent Document 1. As shown in FIG. 10, the small electrode group 102 covered with the resin film 101 is divided by a plurality of metal partitions 104. By storing in the partitioned container 103, the heat generated in each electrode group 102 can be efficiently released to the outside of the container via the metal partition 104.

  However, as shown in FIG. 10, since the plurality of small electrode groups 102 housed in the container 103 are completely separated by the partition 104, for example, sudden gas generation occurs in some of the small electrode groups 102. When this abnormality occurs, the internal pressure of the storage portion in which the small electrode group 102 is stored rapidly increases, and as a result, a problem arises in that the abnormally generated gas is ejected from the container 103.

  On the other hand, Patent Document 2 describes a method of communicating a plurality of containers containing small electrode groups with each other through a communication path.

  11 and 12 are cross-sectional views showing the configuration of the battery case described in Patent Document 2. As shown in FIG. 11, the battery case 201 that stores a plurality of electrode groups is divided into storage units separated from each other. 202, and the electrode group 203 is accommodated in the accommodating portion 202, respectively. Then, as shown in FIG. 12, in the lid 204 provided on the upper part of the battery case 201, through holes 205 are formed in the vicinity of the boundary between the adjacent storage portions 202, and further, the communication passages that communicate the through holes 205 with each other. 206 is formed above the lid 204.

With such a configuration, the storage units 202 partitioned from each other share a space with each other by the communication path 206, so that the gas generated in the electrode group 203 that has been deteriorated may be released to the other storage units 202. it can. Thereby, the deterioration of each electrode group 203 can be balanced, and the lifetime reduction of the whole battery can be prevented.
JP 2000-348696 A JP 2001-057199 A JP 2001-185225 A

  The method described in Patent Document 2 can balance the deterioration of each electrode group 203 because the gas generated in some of the storage units 202 can be released to the other storage units 202 via the communication path 206. Although the communication path 206 is formed above the lid 204, the volume occupied by the communication path 206 is very small compared to the volume of the entire storage unit 202.

  This is because the method described in Patent Document 2 is intended to be applied to a nickel metal hydride battery, and it is necessary to prevent the electrolytic solution from moving between the storage portions 202 and self-discharging. Therefore, as shown in FIG. 12, the communication path 206 formed in the upper part of the lid 204 is provided with a measure such as further providing a weir 207 for preventing the short circuit of the electrolyte. Has been.

  As described above, in the nickel metal hydride battery, although the position where the communication path 206 is provided (above the lid 204) is limited, in the first place, in the nickel metal hydride battery, the positive electrode potential is always close to the oxygen generation potential. For this reason, gas is constantly generated in the storage unit 202, and the gas generated in the storage unit 202 is normally configured to be absorbed by reacting with protons in the hydrogen storage alloy of the negative electrode. Therefore, the volume occupied by the communication path 206 is sufficiently large to achieve the purpose of maintaining a uniform internal pressure variation in each storage portion 202.

  However, in a non-aqueous electrolyte secondary battery such as a lithium ion battery, for example, when a positive electrode plate and a negative electrode plate are short-circuited due to foreign matter or the like, and an abnormal current is generated due to this short-circuit, it accompanies thermal decomposition of the active substance. Vaporization, evaporation of the electrolyte accompanying heat generation in the short-circuit portion, etc. may occur suddenly. When such gas is generated suddenly in some electrode groups 203, it is formed on the top of the lid 204. With only the communication path 206, it is difficult to quickly release the abnormally generated gas to the other storage unit 202.

  In the case of a lithium ion battery, since a very thin metal foil is used for the current collectors constituting the positive electrode plate and the negative electrode plate, a cylindrical shape in which the positive electrode plate and the negative electrode plate are wound with a separator interposed therebetween. When an abnormal gas is generated in a part of the storage portions 202 and the internal pressure rises, there is a risk that the electrode group may be displaced. If a misalignment occurs, a vicious cycle occurs in which the generation of abnormal gas is further promoted.

  The present invention has been made in view of such problems, and its main purpose is a sealed secondary battery in which a plurality of electrode groups are housed in a battery case, and the characteristics of each electrode group are stable and highly reliable. The object is to provide a sealed secondary battery.

  The sealed secondary battery according to the present invention is a non-aqueous electrolyte secondary battery in which a plurality of cylindrical electrode groups obtained by winding a positive electrode plate and a negative electrode plate through a separator are enclosed in a battery case. The battery case includes a plurality of cylindrical storage portions that respectively store a plurality of electrode groups, and a communication portion that connects storage portions adjacent to each other, and the inner periphery of the storage portion is the outer periphery of the electrode group. And the communication portion is formed along the side surface of the storage portion.

  By adopting such a configuration, even if abnormal gas is generated in some of the storage units, the gas is quickly released to the adjacent storage unit via the communication portion formed along the side surface of the storage unit. In addition, since the volume occupied by the communication section itself can be increased, the characteristics of the electrode group stored in each storage section can be stabilized.

  In addition, since the cylindrical electrode group is stored in a cylindrical storage portion having an inner periphery of substantially the same shape, the entire inner periphery of the storage portion can be maintained while pressing the outer periphery of the electrode group, Even if abnormal gas is generated in the storage portion and the internal pressure rises, it is possible to suppress the displacement of the electrode group.

  In addition, when the electrolytic solution filled in each storage part is a non-aqueous electrolyte or an organic gel electrolyte, it is not an aqueous system like an alkaline aqueous solution that is an electrolytic solution of a nickel-metal hydride battery. The speed is large and the configuration of the present application is particularly effective.

  Furthermore, the end portions of the plurality of storage portions are formed as open ends that form a substantially elliptical shape along the envelope of the outer periphery of each storage portion. If it is made the structure which seals with the sealing part which consists of the same ellipse shape, a sealing part can be easily sealed by welding etc. to an opening end.

  According to the sealed secondary battery according to the present invention, even if abnormal gas is generated in a part of the storage units, the storage unit is quickly connected to the adjacent storage unit through the communication unit formed along the side surface of the storage unit. Gas can be released and the outer periphery of the electrode group is maintained over the entire inner periphery of the storage portion, so that the displacement of the electrode group can be effectively suppressed. Thereby, the characteristic of each electrode group is stabilized, and a sealed secondary battery with high reliability and safety can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a perspective view schematically showing a configuration of a battery case 10 used in a sealed secondary battery according to an embodiment of the present invention.

  As shown in FIG. 1, the battery case 10 includes a plurality of cylindrical storage portions 12 a to 12 d that respectively store a plurality of electrode groups, and communication portions 13 a to 13 c that connect the storage portions 12 a to 12 d adjacent to each other. I have. The inner peripheries of the storage portions 12a to 12d have substantially the same shape as the outer periphery of the electrode group, and the communication portions 13a to 13c are formed along the side surfaces of the storage portions 12a to 12d.

  Here, the electrode group 20 accommodated in the battery case 10 has a cylindrical shape formed by winding a positive electrode plate 21 and a negative electrode plate 22 through a separator 23 as shown in FIG. 20 is stored in each of the storage portions 12a to 12d with almost no gap.

  FIG. 3 is a cross-sectional view schematically showing a configuration of a sealed secondary battery 30 in which a plurality of cylindrical electrode groups 20 are enclosed in a battery case 10.

  As shown in FIG. 3, the electrode groups 20 a to 20 d are respectively stored in the plurality of storage portions of the battery case 10. The positive electrode lead 24 welded to the end of the positive electrode plate 21 is welded to the positive electrode current collector plate 31, and the negative electrode lead 25 welded to the end of the negative electrode plate 22 is welded to the bottom of the battery case 10. The upper open end of the battery case 10 is welded and sealed with a sealing plate 32, and the positive electrode current collector plate 31 is welded to a pole column 34 provided on the sealing plate 32 via a lead 33. The sealing plate 32 and the pole column 34 are insulated by a gasket 35. The electrolyte is injected from an injection port 36 provided in the sealing plate 32, and a safety valve 37 is provided in a part of the sealing plate 32.

  Even if abnormal gas is generated in some of the storage portions 12a to 12d, the sealed secondary battery configured in this way is connected via the communication portions 13a to 13c formed along the side surfaces of the storage portions 12a to 12d. Thus, the gas can be quickly released to the adjacent storage portions 12a to 12d.

  Further, since the cylindrical electrode groups 20a to 20d are accommodated in the cylindrical accommodating portions 12a to 12d having substantially the same inner circumference, the electrode groups 20a to 20d are disposed on the entire inner circumference of the accommodating portions 12a to 12d. The outer periphery of 20d can be maintained while being held down. Thereby, even if abnormal gas is generated in the storage portion and the internal pressure rises, the displacement of the electrode group can be suppressed.

  Moreover, when the electrolyte with which each storage part 12a-12d is filled is a nonaqueous electrolyte material, the gas amount and gas generation speed which generate | occur | produce at the time of abnormality are large, and communication part 13a-13c is along the side surface of storage part 12a-12d. The effect of securing the space by forming is great. The same effect can also be obtained when an organic gel electrolyte material is used.

  By exhibiting the above effects, it is possible to stabilize the characteristics of the electrode groups 20a to 20d housed in the housing portions 12a to 12d, and to realize a highly reliable sealed secondary battery. it can.

  The storage portions 12a to 12d and the electrode groups 20a to 20d are not limited to a perfect circular cylindrical shape, but may be, for example, an elliptical cylindrical shape (long cylindrical shape) formed by crushing a cylindrical electrode group. It may be.

  FIG. 4 is a perspective view schematically showing the configuration of the battery case 10 used in the sealed secondary battery in the embodiment of the present invention when the storage portion and the electrode group are long cylindrical.

  As shown in FIG. 4, the battery case 10 includes a plurality of long cylindrical storage portions 12 a to 12 d that respectively store a plurality of electrode groups, and communication portions 13 a to 13 c that connect the storage portions 12 a to 12 d adjacent to each other. It has. The inner peripheries of the storage portions 12a to 12d have substantially the same shape as the outer periphery of the electrode group, and the communication portions 13a to 13c are formed along the side surfaces of the storage portions 12a to 12d.

  Here, the electrode group 20 housed in the battery case 10 has a long cylindrical shape in which a positive electrode plate 21 and a negative electrode plate 22 are wound through a separator 23 as shown in FIG. The group 20 is stored in the storage units 12a to 12d with almost no gap.

  Even if abnormal gas is generated in some of the storage portions 12a to 12d, the sealed secondary battery configured in this way is connected via the communication portions 13a to 13c formed along the side surfaces of the storage portions 12a to 12d. Thus, the gas can be quickly released to the adjacent storage portions 12a to 12d.

  In addition, since the long cylindrical electrode group 20 is stored in the long cylindrical storage portions 12a to 12d having an inner periphery of substantially the same shape, the entire inner periphery of the storage portions 12a to 12d It can be maintained while pressing the outer periphery. Thereby, even if abnormal gas is generated in the storage portion and the internal pressure rises, the displacement of the electrode group can be suppressed.

  The materials of the storage portions 12a to 12d and the communication portions 13a to 13c are not particularly limited. However, if the storage portions 12a to 12d and the communication portions 13a to 13c are formed integrally, the strength of the battery case 10 is increased and the number of parts is increased. This is advantageous in terms of cost and quality.

  The battery case 10 can be formed by various methods. For example, the storage portions 12a to 12d and the communication portions 13a to 13c can be integrally formed using an extrusion method. Moreover, if DI (Drawing & Ironing) method is used, the accommodating parts 12a-12d, the communication parts 13a-13c, and a bottom part can also be formed integrally. Moreover, after forming the ellipse-shaped storage part, you may form the communication parts 13a-13c by press work.

  The sealed secondary battery in the present invention is not particularly limited with respect to the configuration other than the above-described configuration described in the present embodiment, and various configurations adopted in ordinary sealed secondary batteries are applied. obtain.

  For example, as a material of the battery case, iron, nickel, iron nickel plating, stainless steel, aluminum, or the like can be used.

  The current collector constituting the positive electrode plate is an aluminum foil or a perforated body, and the positive electrode active material is a composite oxide such as lithium cobaltate, lithium nickelate, lithium manganate, and lithium iron phosphate. Or a modified product thereof can be used. As a modified body, elements such as aluminum, magnesium, cobalt, nickel and manganese can be mixed and contained. Further, the surface of the positive electrode active material may be coated with another material. As the conductive agent, graphite, carbon black, conductive oxide, metal powder or the like that is stable under the positive electrode potential is used. As the binder, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or the like that is stable at the positive electrode potential is used.

  In addition, a copper foil or a copper perforated body is used for the current collector constituting the negative electrode plate, and the negative electrode active material includes natural graphite, artificial graphite, aluminum and various alloys mainly composed thereof, tin oxide, A metal oxide such as silicon oxide or a metal nitride can be used. As the conductive agent, graphite, carbon black, conductive oxide, metal powder or the like that is stable under a negative electrode potential is used. As the binder, styrene-butadiene copolymer rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or the like that is stable under a negative electrode potential is used.

  For the separator, a microporous film made of polyolefin, a nonwoven fabric, or the like is used.

  Note that the positive electrode plate 21 and the negative electrode plate 22 shown in FIG. 2 are formed by applying a positive electrode active material kneaded with the above-described conductive agent and binder to a current collector, and forming a positive electrode on an uncoated portion at one end of the current collector. It is formed by welding the lead 24 or the negative electrode lead 25. Then, the electrode group 20 is formed by winding the positive electrode plate 21 and the negative electrode plate 22 through the separator 23 so that the positive electrode lead 24 and the negative electrode lead 25 are taken out from different directions.

The non-aqueous electrolyte mainly includes a non-aqueous solvent and a solute, and a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) or lithium tetrafluoroborate (LiBF ₄ ) is used as the solute. . As the non-aqueous solvent, cyclic carbonates such as ethylene carbonate and propylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are used. In addition, a non-aqueous solvent may be used individually by 1 type, but may combine 2 or more types. Moreover, what added additives, such as vinylene carbonate, cyclohexylbenzene, diphenyl ether, may be used.

  As the organic gel electrolyte, a polymer material containing a non-aqueous electrolyte can be used.

  Further, as the gasket 35, a cross-linked polypropylene (PP) resin, polybutylene terephthalate (PBT) resin, polyphenylene sulfide (PPS) resin, perfluoroalkoxyalkane (PFA) resin, polytetrafluoroethylene (PTFE) resin, or the like is used. .

  Further, as the material of the sealing plate 32, iron, nickel, iron nickel plating, stainless steel, aluminum, a clad material thereof, or the like is used.

  Examples of the secondary battery of the nonaqueous electrolyte or organic gel electrolyte suitable for the present invention include a lithium ion battery and a lithium ion polymer battery.

(Modification of this embodiment)
In the sealed secondary battery according to the present invention, after the plurality of electrode groups are accommodated in the accommodating portions 12a to 12d, the opening end of the battery case 10 is sealed by the sealing portion. As shown in FIG. 1, since it has a constricted shape in the communication portions 13a to 13c, for example, when the sealing portion is sealed to the opening end of the battery case 10 by welding or the like, a complicated process is required as compared with normal welding. Cost.

  In this modification, the configuration of the battery case 10 that is improved in terms of manufacturing will be described with reference to FIGS. 6 to 9.

  FIG. 6 is a diagram showing the configuration of the battery case 10 in the first modified example. The basic configuration is the same as that shown in FIG. 1, but one end of the plurality of storage portions 12 a to 12 d (see FIG. 6). Then, the upper end portion) is characterized in that it forms an open end 14 that is deformed into a substantially oval shape along the outer envelope of each of the storage portions 12a to 12d.

  When the opening end 14 having such a shape is welded at the sealing portion, the sealing portion can be easily welded by making the shape (planar shape) of the sealing portion substantially the same as the outer periphery of the opening end 14. it can.

  Even in such a configuration, the electrode groups 20a to 20d can be maintained while holding the electrode groups 20a to 20d in most of the storage portions 12a to 12d except for the area near the opening end. Therefore, even if abnormal gas is generated in the storage portion and the internal pressure increases, the effect of suppressing the displacement of the electrode group is not lost.

  FIG. 7 is a diagram showing the configuration of the battery case 10 in the second modification, and the other ends (lower end portions in the drawing) of the plurality of storage portions 12a to 12d are also substantially similar to those shown in FIG. The open end 15 is deformed into an oval shape. For example, when the bottom portion of the battery case 10 is not integrally formed with the storage portions 12a to 12d and the communication portions 13a to 13c, it is easy to weld the bottom portion of the battery case 10 with the sealing portion.

  FIG. 8 is a diagram illustrating the configuration of the battery case 10 according to the third modification. In the battery case 10 illustrated in FIG. 6, the other ends (lower end portions in the drawing) of the storage portions 12 a to 12 d are flat sealing. It is sealed by the part 16, and is characterized in that protrusions 16a to 16d are formed on the inner surface of the sealing part 16.

  In the present invention, since the cylindrical electrode groups 20a to 20d are accommodated in the cylindrical accommodating portions 12a to 12d having substantially the same inner periphery, the electrode groups 20a to 20d are placed on the inner walls of the accommodating portions 12a to 12d. However, it is still necessary to secure a slight gap when the electrode groups 20a to 20d are stored in the storage portions 12a to 12d. As a result, the positions of the electrode groups 20a to 20d housed in the housing portions 12a to 12d are slightly varied, which may cause variations in the characteristics of the electrode groups.

  In such a case, the electrode groups 20a to 20d are accommodated in the storage portion 12a so that the winding core portions of the electrode groups 20a to 20d are fitted to the protrusions 16a to 16d provided on the bottom of the battery case 10, respectively. If it accommodates in -12d, the variation in the position of electrode group 20a-20d can be suppressed.

  FIG. 9 is a diagram illustrating the configuration of the battery case 10 according to the fourth modification. In the battery case 10 illustrated in FIG. 6, the shapes of the communication portions 13 a to 13 c are linear at least near the center. It is characterized by the points processed in this way. By adopting such a configuration, the volume of the communication portions 13a to 13c can be increased without impairing the operation and effect of the storage portions 12a to 12d maintaining the electrode groups 20a to 20d. The reliability and safety of the secondary battery can be further improved.

  Hereinafter, a specific method for manufacturing a sealed secondary battery according to an embodiment of the present invention will be described by taking a lithium ion battery (nonaqueous electrolyte secondary battery) as an example.

(1) Production of Battery Case Using a steel plate extrusion method, a battery case 10 having the shape of storage portions 12a to 12d and communication portions 13a to 13c having a thickness of about 0.25 mm as shown in FIG. Form. Thereafter, the bottom having a shape matching this shape is welded with a laser.

(2) Preparation of sealing plate The sealing plate 32 as shown in FIG. 3 is produced using an iron plate. The sealing plate 32 is opened when the internal pressure increases due to thinning and grooving, and a safety valve 37 for releasing gas, an electrolyte injection port 36, and aluminum for guiding the positive electrode potential to the outside of the battery case 10. And the gasket 35 made of a cross-linked polypropylene (PP) resin for insulating the sealing plate 32 and the pole 34 from each other.

(3) Preparation of positive electrode plate 85 parts by weight of lithium cobaltate powder as a positive electrode mixture, 10 parts by weight of carbon powder as a conductive agent, and N-methyl-2-pyrrolidone of polyvinylidene fluoride (PVDF) as a binder ( NMP) solution is mixed with 5 parts by weight of PVDF. This mixture is applied to an aluminum foil having a thickness of 15 μm, dried, and then rolled to produce a positive electrode plate 21 having a thickness of about 100 μm. The positive electrode plate 21 is provided with a positive electrode lead 24 made of aluminum.

(4) Production of Negative Electrode Plate An artificial graphite powder is mixed with 95 parts by weight as a negative electrode mixture, and an NMP solution of PVDF as a binder is mixed with PVDF corresponding to 5 parts by weight. This mixture is applied to a copper foil having a thickness of 10 μm, dried, and then rolled to produce a negative electrode plate 22 having a thickness of about 110 μm. The negative electrode plate 22 is provided with a copper negative electrode lead 25.

(5) Preparation of non-aqueous electrolyte As a non-aqueous solvent, ethylene carbonate and ethyl methyl carbonate are mixed at a volume ratio of 1: 1, and lithium hexafluorophosphate (LiPF ₆ ) is 1 mol / L as a solute. To dissolve. 15 ml of the non-aqueous electrolyte prepared in this way is used.

(6) Production of Electrode Group A separator 23 having a thickness of 25 μm is disposed between the positive electrode plate 21 and the negative electrode plate 22 and wound to produce cylindrical electrode groups 20a to 20d having a diameter of 23 mm and a height of 57 mm.

(7) Production of sealed secondary battery Four cylindrical electrode groups 20a to 20d are inserted into the battery case 10, and the negative electrode lead 25 of each electrode group 20a to 20d and the bottom of the battery case 10 are resistance-welded. Connecting. Moreover, the positive electrode lead 24 of the electrode groups 20 a to 20 d is welded to the current collector plate 31, and the current collector plate 31 and the pole column 34 provided on the sealing plate 32 are welded with the aluminum lead 33. Thereafter, the sealing plate 32 and the battery case 10 are sealed by laser welding. Further, a nonaqueous electrolyte is injected from an inlet 36 provided in the sealing plate 32, and finally the inlet 36 is sealed to obtain a sealed nonaqueous electrolyte secondary battery.

  Next, with respect to the lithium ion battery manufactured by the above method, the configuration of the battery case 10 is the same as that of the present embodiment shown in FIG. 1 and the first to fourth modifications shown in FIGS. In the case of the configuration in the example, the cycle life characteristics and the variation in the number of cycles until the end of the life were evaluated. The design capacity of the battery was 8 Ah, and 10 batteries were produced and evaluated. Moreover, the lithium ion battery produced using the conventional battery case 401 as shown to Fig.13 (a), (b) was evaluated as a comparative example.

  The evaluation method is as follows. First, it was aged for 3 days in an atmosphere of 45 ° C. while being charged to 4.1 V at 1 A. Then, it discharged to 3V at 1A in 25 degreeC atmosphere. Thereafter, a constant current charge was performed until the voltage reached 4.2 V at 8 A in a 45 ° C. atmosphere, and then a cycle of discharging to 3 V at 8 A was repeated. And the variation of the average cycle number when capacity | capacitance cut | disconnected 6 Ah, and the cycle number until it reaches a lifetime were each evaluated.

  In addition, each variation (dispersion) Y was calculated | required by following Numerical formula 1.

Here, Y is the variation in the number of cycles when the capacity is less than 6 Ah, A is the average number of cycles of 10 when the capacity of the lithium ion battery is less than 6 Ah, and B _n is 10 lithium This is the number of cycles when the capacity of the nth lithium ion battery of the ion batteries is less than 6 Ah.

  Table 1 shows each evaluation result when the configuration of the battery case 10 is the configuration of the present embodiment, the first to fourth modifications, and the comparative example.

  As can be seen from the results in Table 1, when the configuration of the battery case 10 is the configuration of the present embodiment and the first to fourth modifications, all have stable characteristics as compared to the configuration of the comparative example. A lithium ion battery could be obtained.

  By the way, Patent Document 3 discloses a battery case in which a plurality of long cylindrical electrode groups are housed in a housing portion in a state where an internal space is shared.

  FIG. 14 is a diagram showing the configuration of the battery case 301 disclosed in Patent Document 3, and shows a state in which a plurality (two in FIG. 14) of long cylindrical electrode groups 302 are accommodated in the battery case 301. It is a thing. A heat dissipating solid member 304 is disposed between the battery case 301 and the electrode group 302.

  Certainly, since the solid member 304 is formed in accordance with the gap shape between the battery case 301 and the electrode group 302, in addition to the heat dissipation effect, the effect of suppressing vibration of the electrode group 302 is also exhibited. Looks similar to the present invention and configuration.

  However, the solid member 304 is configured separately from the battery case 301. Actually, the electrode group 302 is housed in the battery case 301 after the solid member 304 is inserted into the gap between the electrode groups 302. is there. Therefore, in addition to the complicated process such as positioning at the time of manufacturing, the outer periphery of the electrode group is not maintained uniformly due to process variations, etc., and as a result, abnormal gas is generated in the storage part and the internal pressure rises. It is not possible to uniformly suppress the group deviation.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible. For example, in the above-described embodiment, the storage portions 12a to 12d and the communication portions 13a to 13c are configured of thin plates having the same thickness, but at least the inner periphery of the storage portions 12a to 12d is the outer periphery of the electrode groups 20a to 20d. As long as it has substantially the same shape, the communicating portions 13a to 13c may have a thickness such that the outer shape becomes flat, for example.

  In the above embodiment, the positive electrode plate 21 and the negative electrode plate 22 are connected to the current collector plate 31 and the bottom of the battery case 10 via the positive electrode lead 24 and the negative electrode lead 25, respectively. The electrode groups 20a to 20d having a so-called tabless structure, in which the current collector plates are welded to the end portions of the current collectors constituting the negative electrode plate 22 (uncoated portions of the mixture), lead each electrode group. Alternatively, it may be configured to be connected to the current collector 31 and the bottom of the battery case 10 by direct welding or the like.

  INDUSTRIAL APPLICABILITY The present invention is a sealed secondary battery in which a plurality of electrode groups are housed in a battery case, and the characteristics of each electrode group are stable and useful for a highly reliable sealed secondary battery.

It is the perspective view which showed the structure of the battery case in embodiment of this invention. It is the figure which showed the structure of the electrode group in this embodiment. It is sectional drawing which showed the structure of the sealed secondary battery in this embodiment. It is the perspective view which showed the structure of the battery case in embodiment of this invention. It is the figure which showed the structure of the electrode group in this embodiment. It is the figure which showed the structure of the battery case in a 1st modification. It is the figure which showed the structure of the battery case in a 2nd modification. It is the figure which showed the structure of the battery case in a 3rd modification. It is the figure which showed the structure of the battery case in a 4th modification. It is the perspective view which showed the structure of the battery case of the conventional sealed secondary battery. It is sectional drawing which showed the structure of the battery case of the conventional sealed secondary battery. It is sectional drawing which showed the structure of the communicating path provided in the conventional battery case. It is the figure which showed the structure of the battery case in a comparative example. It is the figure which showed the structure of the battery case of the conventional sealed secondary battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Battery case 12a-12d Storage part 13a-13c Communication part 14,15 Open end 16 Sealing part 16a-16d Protrusion part 20, 20a-20d Electrode group 21 Positive electrode plate 22 Negative electrode plate 23 Separator 24 Positive electrode lead 25 Negative electrode lead 30 Sealing type Secondary battery 31 Positive electrode current collector plate 32 Sealing plate (sealing part)
33 Aluminum reed 34 Polar column 35 Gasket 36 Inlet 37 Safety valve

Claims (7)

A sealed secondary battery in which a plurality of cylindrical electrode groups obtained by winding a positive electrode plate and a negative electrode plate through a separator are enclosed in a battery case,
The battery case is
A plurality of cylindrical storage portions that respectively store the plurality of electrode groups;
A communication portion that connects the storage portions adjacent to each other,
The inner periphery of the storage part has substantially the same shape as the outer periphery of the electrode group,
The communication part is a sealed secondary battery formed along a side surface of the storage part.   The sealed secondary battery according to claim 1, wherein the electrolytic solution filled in the storage portion is made of a non-aqueous electrolyte or an organic gel electrolyte.   The sealed secondary battery according to claim 1, wherein the storage portion and the electrode group have a long cylindrical shape. The end portions of the plurality of storage portions have open ends that are deformed into a substantially oval shape along the outer envelope of each storage portion,
2. The sealed secondary battery according to claim 1, wherein the opening end is sealed by a sealing portion having an oval shape substantially the same as the outer periphery of the opening end.   The sealed secondary battery according to claim 1, wherein the plurality of storage units and the communication unit that connects the storage units are integrally formed. The end of the storage part is sealed by a flat sealing part,
A protrusion is formed on the inner surface of the sealing portion,
The sealed secondary battery according to claim 1, wherein a winding core portion of the electrode group is fitted with the protrusion.   The sealed secondary battery according to claim 1, wherein the sealed secondary battery is a lithium ion battery.

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