JP2013105586A - Electrode body for secondary battery, secondary battery and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode body for a secondary battery which can reduce a dead space of the secondary battery having a plurality of winding type power generation elements, attain improved volume energy density, and also prevent power generation element from being overcharged and over-discharged.SOLUTION: An electrode body 10 for the secondary battery is an electrode body for a winding type secondary battery in which a belt-like positive electrode 11 having an active material layer 11a and a belt-like negative electrode 12 having an active material layer 12a are wound while a belt-like separator 13 is interposed between both electrodes. The belt-like positive electrode 11 and the belt-like negative electrode 12 are wound so as to make two wound parts 14 by each single belt-like electrode.

Description

  The present invention relates to an electrode body for a secondary battery, a secondary battery, and a vehicle, and more particularly, an electrode body for a secondary battery having a plurality of wound electrode portions, a secondary battery, and a vehicle equipped with the secondary battery. About.

  Secondary batteries are widely used as a power source because they can be recharged and used repeatedly. In recent years, there has been a demand for reduction in the use of fossil fuels (restriction of carbon dioxide emissions). Secondary batteries used for main and auxiliary power sources such as electric vehicles and hybrid vehicles are charged and discharged with large currents and secondary batteries. Increased capacity of batteries is required.

  In general, a large-capacity secondary battery accommodates a wound power generation element (electrode body) in a rectangular box-shaped battery case. However, as shown in FIG. 8 (a), when a cylindrical wound power generation element 52 is accommodated in a rectangular box-shaped battery case 51, gaps (dead spaces) are formed in the side surfaces of the four corners of the battery case 51. There arises a problem that the volume energy density is reduced. Even if the battery case 51 is cylindrical in order to eliminate the gap, it is easy to waste space where the secondary battery is mounted. Especially in applications such as electric vehicles, a large number of batteries are arranged side by side. It becomes difficult to eliminate waste.

  Even when only one long cylindrical power generation element is housed in the battery case 51 as the power generation element 52, it is inevitable that a large gap is generated in the curved side surface of the long cylindrical shape. As shown in FIGS. 8B and 8C, a case where two long cylindrical power generation elements 52 are accommodated in a battery case 51 of the same size and a case where four power generation elements 52 are accommodated. When the four power generating elements 52 are accommodated, the total of the gaps (hatched portions) becomes smaller.

  Therefore, conventionally, a plurality of (for example, two) wound-type power generation elements in which strip-shaped positive and negative electrodes are wound in a long cylindrical shape via a strip-shaped separator are arranged with the flat side surfaces of the long cylindrical shape aligned with each other. However, a battery that constitutes a single battery by connecting in parallel has been proposed. The plurality of power generating elements are connected to a positive electrode current collector (positive electrode current collector terminal) in which a metal plate is repeatedly bent into a corrugated plate shape at one end face side of the active material non-applied portion, and the other end face side active material A negative electrode current collector (negative electrode current collector terminal) in which a metal plate is repeatedly bent into a corrugated plate shape is connected to the non-application portion. Accordingly, the two power generation elements are connected in parallel in the battery case to constitute one unit cell.

JP 2000-223109 A

  In the secondary battery described in Patent Document 1, a plurality of winding-type power generation elements are housed in one battery case 51 to form one unit cell. The dead space can be reduced as compared with the case where one winding type power generation element is accommodated in the battery case 51. However, since a plurality of power generation elements are connected in parallel at the current collecting terminals, there is a difference in the capacity balance of each power generation element due to the difference in internal resistance between each power generation element. Power generation elements that are easily discharged or overcharged are likely to occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the dead space of a secondary battery having a plurality of winding type power generation elements and to improve the volume energy density. Another object of the present invention is to provide an electrode body for a secondary battery and a secondary battery, and a vehicle equipped with the secondary battery, in which power generation elements that are overdischarged and overcharged are not easily generated.

  In order to achieve the above object, according to the first aspect of the present invention, a belt-like positive electrode having an active material layer and a belt-like negative electrode having an active material layer are wound with a belt-like separator interposed therebetween. In the electrode body for a rechargeable secondary battery, the belt-like positive electrode and the belt-like negative electrode are each wound by a single belt-like electrode so that two winding portions exist.

  The secondary battery constructed by accommodating the secondary battery electrode body of the present invention in a rectangular box-shaped battery case accommodates the secondary battery electrode body formed by one winding part in the same battery case. Compared to the secondary battery configured as described above, the dead space is reduced. Accordingly, it is possible to reduce the dead space of the secondary battery having a plurality of winding type power generation elements to improve the volume energy density, and it is difficult to generate power generation elements that are overdischarged or overcharged.

  According to a second aspect of the present invention, in the first aspect of the invention, the strip-like positive electrode and the strip-like negative electrode are each formed by a single strip-like electrode without a joint. Therefore, in this invention, when the secondary battery 21 is comprised, the capacity | capacitance of each winding part can be made the same by making the length of the strip | belt-shaped positive electrode and strip | belt-shaped negative electrode which comprise each winding part the same.

  According to a third aspect of the present invention, in the first aspect of the invention, each of the belt-like positive electrode and the belt-like negative electrode is formed of a single belt-like electrode in which ends of two belt-like electrodes are joined to each other. Yes. In order to wind a strip electrode so that two winding parts exist, it cannot wind with the winding device which winds one winding part, but a new device is needed. However, if it is allowed that the belt-like positive electrode and the belt-like negative electrode are each composed of one belt-like electrode in which the ends of the two belt-like electrodes are joined together, a winding device that winds one winding portion is used. By joining the belt-like positive electrodes and the belt-like negative electrodes constituting the two wound portions formed, a secondary battery electrode body having two winding portions can be manufactured.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein each of the belt-like positive electrode and the belt-like negative electrode is wound around each of a plurality of positive electrodes. The tab portion and the plurality of negative electrode tab portions are integrally formed to protrude on the same side in the winding axis direction, and the plurality of positive electrode tab portions and the plurality of negative electrode tab portions are respectively in relation to the winding axis. Overlapping in the radial direction. When the secondary battery electrode body of the present invention is used, the secondary battery electrode body in which the positive electrode tab portion of the belt-like positive electrode and the negative electrode tab portion of the belt-like negative electrode are formed to protrude on the opposite side in the winding axis direction is used. Compared to the case, the dead space of the secondary battery can be reduced and the volume energy density can be improved.

  The invention according to claim 5 is a plurality of secondary battery electrode bodies according to any one of claims 1 to 4, one positive current collecting terminal and one negative current collector. It is the electrode body for secondary batteries connected in parallel through the terminal. The secondary battery electrode body of the present invention is in a state in which a secondary battery electrode body having one winding portion is mixed, via one positive current collector terminal and one negative current collector terminal. Compared to the electrode bodies for secondary batteries connected in parallel, the labor for connection with the current collector terminal for positive electrode and the current collector terminal for negative electrode is reduced. In addition, when a secondary battery is configured using the secondary battery electrode body of the present invention, the interior of each power generation element is compared to a secondary battery configured using the latter secondary battery electrode body. Due to the difference in resistance, it is difficult to produce a difference in capacity balance, and it is difficult to generate power generation elements that are overdischarged or overcharged.

  The invention according to claim 6 is a secondary battery comprising the electrode body for a secondary battery according to claim 5. The secondary battery according to the present invention includes a plurality of secondary battery electrode bodies each having one winding portion connected in parallel via one positive current collector terminal and one negative current collector terminal. Compared with a secondary battery provided with an electrode body for a secondary battery, power generation elements that become overdischarged and overcharged are less likely to occur.

  A seventh aspect of the present invention is a vehicle equipped with the secondary battery according to the sixth aspect. Therefore, the vehicle of the present invention can achieve the effect of the secondary battery according to claim 6.

  According to the present invention, it is possible to reduce the dead space of a secondary battery having a plurality of wound-type power generation elements, to improve the volume energy density, and to generate power generation elements that are overdischarged and overcharged. It is possible to provide a secondary battery electrode body, a secondary battery, and a vehicle on which the secondary battery is mounted.

1 shows a first embodiment, (a) is a schematic perspective view of an electrode body for a secondary battery, (b) is a schematic diagram showing a winding state of two winding parts, (c) is a positive electrode, a negative electrode, and The schematic perspective view of the electrode body for secondary batteries in the middle of winding which shows the relationship of a separator. The schematic exploded perspective view which shows the relationship between a current collection terminal and a tab part. The schematic cross section of a secondary battery. The schematic exploded perspective view of the electrode body for secondary batteries of 2nd Embodiment. The schematic perspective view which shows the joining relationship of the positive electrode and negative electrode of the electrode body for secondary batteries of another embodiment. (A) is a schematic perspective view of the electrode body for secondary batteries of another embodiment, (b) is a schematic diagram which shows the winding state of the two winding parts of another embodiment. The schematic cross section of the secondary battery of another embodiment. (A), (b), (c) is a schematic diagram which shows the relationship between the number of power generation elements at the time of accommodating a power generation element in a square box-shaped case, and useless space.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1A to 1C, a secondary battery electrode body 10 is formed by winding a belt-like positive electrode 11 and a belt-like negative electrode 12 with a belt-like separator 13 interposed therebetween. This is a rechargeable secondary battery electrode body. In this embodiment, the belt-like positive electrode 11 and the belt-like negative electrode 12 are each formed of a single belt-like electrode.

  The strip-shaped positive electrode 11 has an active material layer 11a in which an active material is applied to a metal strip-shaped current collector, and the strip-shaped negative electrode 12 is an active material in which an active material is coated to a metal strip-shaped current collector. It has a layer 12a. The current collector is formed of, for example, a strip-shaped copper foil, and the active material layers 11a and 12a are respectively formed on both surfaces of the current collector. The active material varies depending on the type of secondary battery such as a nickel metal hydride battery and a lithium ion battery. Even in the same type of secondary battery, the active material for the positive electrode and the active material for the negative electrode are different.

  The strip-shaped positive electrode 11, the strip-shaped negative electrode 12, and the separator 13 are wound so that there are two long cylindrical winding portions 14, and the two winding portions 14 are formed to have the same capacity. . That is, the two winding portions 14 are formed so that the lengths of the strip-shaped positive electrode 11 and the strip-shaped negative electrode 12 are the same. As shown in FIG. 1B, the winding direction of the strip-shaped positive electrode 11, the strip-shaped negative electrode 12, and the separator 13 is right-handed (in the same direction) from the inside to the outside at the two winding portions 14, respectively. Yes. FIG. 1B is a view showing the winding direction of the strip-shaped positive electrode 11, the strip-shaped negative electrode 12 and the separator 13, and the four strips of the strip-shaped positive electrode 11, the strip-shaped negative electrode 12 and the separator 13 are combined into one line. Represents.

  In one winding portion 14 of the two winding portions 14, the strip-like positive electrode 11 is disposed inside the strip-like negative electrode 12, and the separator 13 is disposed between the strip-like positive electrode 11 and the strip-like negative electrode 12. There are two sheets, one that is disposed outside the negative electrode 12, and the outermost layer is the separator 13. Moreover, in the other winding part 14, the outermost layer turns into the strip | belt-shaped positive electrode 11, and it winds so that it may become the order of the strip | belt-shaped positive electrode 11, the separator 13, the strip | belt-shaped negative electrode 12, and the separator 13 from the outermost layer side.

  A plurality of positive electrode tab portions 11b and a plurality of negative electrode tab portions 12b are integrally formed on the same side in the winding axis direction in a state of being wound on the belt-like positive electrode 11 and the belt-like negative electrode 12, respectively. At the same time, the plurality of positive electrode tab portions 11b and the plurality of negative electrode tab portions 12b overlap each other in the radial direction with respect to the winding axis. The positive electrode tab portion 11b and the negative electrode tab portion 12b are formed of an active material non-applied portion which is a portion where the active material layers 11a and 12a of the strip-shaped positive electrode 11 or the strip-shaped negative electrode 12 are not formed.

  As shown in FIG. 2, the secondary battery electrode body 10 configured as described above includes a positive electrode current collector terminal 15 connected to the positive electrode tab portion 11 b of the belt-like positive electrode 11, and a negative electrode tab of the belt-like negative electrode 12. By connecting the negative electrode current collecting terminal 16 to the part 12b, the two winding parts 14, that is, the power generation elements are connected in parallel. The positive electrode current collecting terminal 15 and the negative electrode current collecting terminal 16 are each formed by bending a metal plate into a corrugated plate shape, and a positive electrode tab portion 11b or a negative electrode tab portion is provided in each gap between the corrugated plate portions 15a and 16a. The connection is made by sandwiching a large number of 12b pieces and pressing them from both sides and welding them by ultrasonic welding, laser welding or the like. The positive current collecting terminal 15 and the negative current collecting terminal 16 are formed with connecting portions 15b and 16b protruding from the center of the corrugated plate portions 15a and 16a, respectively.

  As shown in FIG. 3, the secondary battery electrode body 10 is housed in a battery case 17, and the connection portion 15 b of the positive electrode current collector terminal 15 is fixed to the positive electrode terminal 18 and electrically connected to the positive electrode terminal 18. Then, the connecting portion 16 b of the negative electrode current collecting terminal 16 is fixed to the negative electrode terminal 19 and electrically connected to the negative electrode terminal 19. And the secondary battery 21 is comprised with the electrolyte solution 20 inject | poured into the battery case 17. FIG.

The secondary battery 21 using the secondary battery electrode body 10 having the above-described configuration is used for various purposes. For example, the secondary battery 21 is also used in a state of being mounted on a vehicle.
Next, the operation of the secondary battery 21 configured as described above will be described. When the secondary battery 21 is discharged, current is taken out from the winding portion 14 as a power generation element constituting the secondary battery 21 through the positive electrode current collecting terminal 15. At this time, in the case of the configuration in which each winding part 14 is formed independently, the internal resistance in each winding part 14 is different, and the capacity of each power generation element is due to the difference in internal resistance between each power generation element. Since there is a difference in balance, power generation elements that are overdischarged easily occur. In addition, since there is a difference in the capacity balance of each power generation element during charging, power generation elements that are overcharged easily occur. However, in the secondary battery electrode body 10 used in the secondary battery 21 of this embodiment, the belt-like positive electrode 11 and the belt-like negative electrode 12 constituting the two winding portions 14 are each one strip-like electrode. Because it is formed, there is no difference in internal resistance among the power generation elements, and overdischarge and overcharge do not occur.

According to this embodiment, the following effects can be obtained.
(1) In the secondary battery electrode body 10, a strip-shaped positive electrode 11 having an active material layer 11a and a strip-shaped negative electrode 12 having an active material layer 12a are wound with a strip-shaped separator 13 interposed therebetween. This is an electrode body for a wound type secondary battery. The belt-like positive electrode 11 and the belt-like negative electrode 12 are each wound by one belt-like electrode so that there are two winding portions 14. A secondary battery 21 configured by accommodating the secondary battery electrode body 10 in a rectangular box-shaped battery case 17 includes a secondary battery electrode body formed in the same battery case 17 by one winding portion. Compared to a secondary battery configured to accommodate the battery, the dead space is reduced. Therefore, the dead space of the secondary battery 21 having a plurality of winding type power generation elements can be reduced to improve the volume energy density, and power generation elements that are overdischarged and overcharged are hardly generated.

  (2) The strip-shaped positive electrode 11 and the strip-shaped negative electrode 12 are each formed by a single strip-shaped electrode without a joint. Therefore, by making the lengths of the strip-shaped positive electrode 11 and the strip-shaped negative electrode 12 constituting each winding portion 14 the same, the capacity of each winding portion 14 can be made the same when the secondary battery 21 is constructed.

  (3) The secondary battery 21 is one secondary battery having two winding portions 14 formed in the same capacity with the strip-shaped positive electrode 11 and the strip-shaped negative electrode 12 formed of a single strip-shaped electrode without a joint. The electrode body 10 is housed in a battery case 17 and configured. Therefore, the internal resistance of each power generation element becomes the same, and it is possible to prevent some power generation elements from being overdischarged or overcharged.

  (4) A plurality of positive electrode tab portions 11b and a plurality of negative electrode tab portions 12b are integrally formed on the same side in the winding axis direction while being wound on the belt-like positive electrode 11 and the belt-like negative electrode 12, respectively. In addition, the plurality of positive electrode tab portions 11b and the plurality of negative electrode tab portions 12b overlap each other in the radial direction with respect to the winding axis. Therefore, when the secondary battery electrode body 10 is used, the secondary battery electrode body in which the positive electrode tab portion 11b and the negative electrode tab portion 12b are formed to protrude on the opposite side in the winding axis direction is used. In comparison, the dead space of the secondary battery 21 can be reduced and the volume energy density can be improved.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. In this embodiment, the secondary battery 21 is configured in a state where a plurality (two) of the secondary battery electrode bodies 10 of the first embodiment having two winding portions 14 are connected in parallel. This is different from the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the basic structure of the positive electrode current collector terminal 25 and the negative electrode current collector terminal 26 of the secondary battery electrode body 30 is the same as that of the positive electrode current collector terminal 15 and the negative electrode current collector terminal 16. The gap spacing and the number of the corrugated plate portions 25a and 26a are different from those of the first embodiment. The positive current collecting terminal 25 is connected to the positive electrode tab portion 11b of the four winding portions 14, and the negative current collecting terminal 26 is connected to the negative electrode tab portion 12b of the four winding portions 14. Four winding portions 14, that is, power generation elements are connected in parallel. Connection portions 25b and 26b projecting from the center of the corrugated plate portions 25a and 26a are formed.

According to this 2nd Embodiment, in addition to the effect similar to (2)-(4) of 1st Embodiment, the following effects can be acquired.
(5) The secondary battery electrode body 30 includes a plurality of secondary battery electrode bodies 10 connected in parallel via one positive current collector terminal 25 and one negative current collector terminal 26. Yes. When the total number of winding parts is the same, the secondary battery electrode body 30 has a secondary battery electrode body having one winding part and the secondary battery electrode body 10 having two winding parts. In comparison with a secondary battery electrode body connected in parallel through one positive current collector terminal 25 and one negative current collector terminal 26 in a state where the The time and labor of connection with the current collecting terminal 16 are reduced. In addition, when the secondary battery 21 is configured using the secondary battery electrode body 30, the overdischarge / overcharge is compared to the secondary battery configured using the latter secondary battery electrode body. It becomes difficult to generate power generation elements.

The embodiment is not limited to the above, and may be embodied as follows, for example.
○ Two winding parts 14 are not the same capacity, and may be somewhat different.
The strip-shaped positive electrode 11 and the strip-shaped negative electrode 12 may each be formed of a single strip-shaped electrode in which two strip-shaped electrodes are joined. In this case, as shown in FIG. 5, the two winding portions 14 manufactured in the same winding direction are joined to each other by joining the ends of the strip-like negative electrode 12 positioned on the outermost periphery, and the separator 13 is sandwiched between them. Then, the end portions of the strip-like positive electrode 11 located inside thereof are joined by joining. The two separators 13 constituting each winding part 14 do not necessarily need to be connected, and the secondary battery electrode body 10 including the two winding parts 14 has four separators 13. . In order to wind the strip electrode so that there are two winding portions 14, it is not possible to wind with a winding device that winds one winding portion, and a new device is required. However, in the case of this embodiment, the belt-like positive electrodes 11 and the belt-like negative electrodes 12 constituting the two winding parts formed by the winding device that winds one winding part 14 are connected to each other. By joining each, the electrode body 10 for secondary batteries which has the two winding parts 14 can be manufactured. By using the same production lot as the strip-shaped positive electrode 11, the strip-shaped negative electrode 12, and the separator 13 constituting each winding section 14, the difference in internal resistance of each winding section 14 can be minimized. The joining is not limited to welding, and may be joined with an adhesive or solder.

  As shown in FIG. 6 (a), the secondary battery electrode body 10 has an active material non-applied portion 11c of the strip-shaped positive electrode 11 and an active material non-applied portion 12c of the strip-shaped negative electrode 12 that is a winding axis of the winding portion 14. It is good also as a structure wound by the state located in the opposite side of a direction. In this case, the degree of freedom of the connection positions of the positive current collector terminals 15 and 25 and the negative current collector terminals 16 and 26 is increased, and it is not necessary to cut away and remove part of the active material non-applied portions 11c and 12c. . As shown in FIG. 7, the secondary battery 21 using the secondary battery electrode body 10 having this configuration is configured such that the winding axis direction of the secondary battery electrode body 10 extends in the left-right direction of the battery case 17. Housed in case 17. Correspondingly, positive current collecting terminals 15 and 25 and negative current collecting terminals 16 and 26 having different shapes are used.

  ○ As shown in FIG. 6B, the winding direction of the strip-like positive electrode 11, the strip-like negative electrode 12 and the separator 13 constituting the two winding portions 14 constituting the secondary battery electrode body 10 is The winding portion 14 may be right-handed and left-handed (in opposite directions) from the inside to the outside.

  The positive electrode current collector terminal and the negative electrode current collector terminal each have a positive electrode tab portion 11b and a belt-like negative electrode 12 of the belt-like positive electrode 11 of the plurality of winding portions 14 constituting the secondary battery electrode bodies 10 and 30, respectively. Any shape that can be joined to the negative electrode tab portion 12b may be used, and a shape having a plurality of welding surfaces may be used without the corrugated plate portions 15a and 16a.

  A secondary battery electrode body having a plurality of winding parts 14 is a plurality of winding type secondary bodies including at least one secondary battery electrode body 10 of the first embodiment or the second embodiment. The battery electrode body may be configured to be connected in parallel via one positive current collecting terminal and one negative current collecting terminal. For example, the electrode body for a secondary battery may have a configuration in which an odd number of winding portions 14 are connected in parallel via one positive current collector terminal and one negative current collector terminal. Also in the case of a secondary battery using this secondary battery electrode body, only a predetermined number of secondary battery electrode bodies having one winding portion 14, one positive current collector terminal and negative current collector Compared with the case where a secondary battery is configured using secondary battery electrode bodies connected in parallel via terminals, power generation elements that are overdischarged and overcharged are less likely to occur.

A plurality of secondary battery electrode bodies 10 may be connected in series to form a secondary battery electrode body.
A secondary battery having a configuration in which the active material non-applied portion 11c of the strip-shaped positive electrode 11 and the active material non-applied portion 12c of the strip-shaped negative electrode 12 are wound in a state of being positioned on the opposite side of the winding portion 14 in the winding axis direction. In the electrode body 10, the active material non-applied portions 11 c and 12 c may be provided in a part without being provided over the entire length of the strip-shaped positive electrode 11 or the strip-shaped negative electrode 12 along the active material layers 11 a and 12 a, respectively.

  DESCRIPTION OF SYMBOLS 10,30 ... Secondary battery electrode body, 11 ... Strip-shaped positive electrode, 11a, 12a ... Active material layer, 11b ... Positive electrode tab portion, 12b ... Negative electrode tab portion, 12 ... Strip-shaped negative electrode, 13 ... Separator, 14 ... Winding Rotating part, 15, 25 ... collector terminal for positive electrode, 16, 26 ... collector terminal for negative electrode, 21 ... secondary battery.

Claims (7)

A band-shaped positive electrode having an active material layer and a band-shaped negative electrode having an active material layer are wound-type secondary battery electrode bodies wound with a band-shaped separator interposed therebetween,
The belt-like positive electrode and the belt-like negative electrode are each wound by a single belt-like electrode so that there are two winding portions.   2. The electrode body for a secondary battery according to claim 1, wherein each of the belt-like positive electrode and the belt-like negative electrode is formed by a single belt-like electrode without a joint.   2. The secondary battery electrode body according to claim 1, wherein each of the belt-like positive electrode and the belt-like negative electrode is formed of one belt-like electrode in which ends of two belt-like electrodes are joined to each other.   The belt-like positive electrode and the belt-like negative electrode are respectively wound in a plurality of positive electrode tab portions and a plurality of negative electrode tab portions formed integrally and projecting on the same side in the winding axis direction, 4. The electrode body for a secondary battery according to claim 1, wherein the plurality of positive electrode tab portions and the plurality of negative electrode tab portions overlap each other in a radial direction with respect to a winding axis. 5.   A plurality of secondary battery electrode bodies according to any one of claims 1 to 4 are connected in parallel via one positive current collector terminal and one negative current collector terminal. An electrode body for a secondary battery.   A secondary battery comprising the secondary battery electrode body according to claim 5.   A vehicle equipped with the secondary battery according to claim 6.