JP2015220044A - Cylindrical secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate potential management of a reference electrode. A power generation element, a positive electrode tab and a negative electrode tab connected to the power generation element, a battery can containing an electrode group, a positive electrode tab, and a negative electrode tab, a can lid for sealing the battery can, and a battery can and a can. A cylindrical secondary battery having a reference electrode arranged in the lid, wherein the can lid has an internal pressure sensitive portion, an outer frame structure, and a top cap, and the reference electrode is a reference electrode tab and an electrode. With the material, the outer frame structure is connected to the electrode material via the reference electrode tab, the positive electrode tab is connected to the top cap, the negative electrode tab is connected to the battery can, and the top cap is connected via the internal pressure sensitive portion. Has a top cap exposed part, the outer frame structure has an outer frame structure exposed part, and the outer frame structure exposed part is formed so as to surround the top cap exposed part. .. [Selection diagram] Figure 2

Description

  The present invention relates to a cylindrical secondary battery.

  Conventionally, as a method for nondestructively measuring each of a positive electrode potential and a negative electrode potential of a secondary battery, a technique of arranging a reference electrode in the secondary battery is known. As a secondary battery having a reference electrode, Patent Document 1 discloses the following technology. A metal case electrically separated from the positive and negative electrode plates and a member made of a positive electrode side and / or a negative electrode side electronic conductor in contact with the nonaqueous electrolyte in the metal case are arranged close to each other, and the metal case potential is used as a reference electrode. By using it, each of the positive electrode potential and the negative electrode potential can be measured without causing a decrease in battery capacity, and highly accurate charge / discharge management can be realized.

JP 2008-108435 A

  When a metal case potential (battery can potential) is used as a reference electrode as in Patent Document 1, there is a problem in a battery module configured by densely integrating a plurality of batteries. That is, since the distance between the battery can and the battery can is close, if a foreign substance such as a water droplet enters the battery module, a circuit may be formed in the battery can serving as a reference electrode via the foreign substance, which may cause a micro short circuit. . As a result, it may be difficult to manage the potential of the reference electrode. An object of the present invention is to facilitate the potential management of the reference electrode.

  The features of the present invention for solving the above problems are as follows, for example.

  A power generation element, a positive electrode tab and a negative electrode tab connected to the power generation element, a battery can that houses the electrode group, the positive electrode tab, and the negative electrode tab, a can lid that seals the battery can, and a battery can and a can lid A canister, the can lid has an internal pressure sensitive part, an outer frame structure, and a top cap, and the reference electrode has a reference electrode tab and an electrode material The outer frame structure is connected to the electrode material via the reference electrode tab, the positive electrode tab is connected to the top cap, the battery can is connected to the negative electrode tab, and the top cap is exposed to the top cap via the internal pressure sensitive part. A cylindrical secondary battery in which the outer frame structure has an outer frame structure exposed portion, and the outer frame structure exposed portion surrounds the top cap exposed portion.

  According to the present invention, the potential of the reference electrode can be easily managed. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an external perspective view showing a cylindrical secondary battery according to an embodiment of the present invention. AA sectional view of a cylindrical secondary battery External view of positive electrode sheet or negative electrode sheet according to one embodiment of the present invention 1 is an external view of a power generation element according to an embodiment of the present invention. 1 is an external view of a reference electrode according to an embodiment of the present invention. FIG. 2 is an external view illustrating a configuration of a reference electrode according to an embodiment of the present invention. The elements on larger scale of FIG. 2 for demonstrating the cross-section of the can lid concerning one Embodiment of this invention The exploded view explaining the composition of the can lid concerning one embodiment of the present invention External view of can lid according to one embodiment of the present invention The external view which shows another form of the can lid which concerns on one Embodiment of this invention 1 is an external view showing the relationship between a cylindrical secondary battery and a battery control board according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  FIG. 1 is an external perspective view of a secondary battery according to this embodiment, and FIG. 2 is a cross-sectional view taken along line AA of the secondary battery according to this embodiment. The secondary battery 1 accommodates a power generation element 3, two insulating sheets 4, a positive electrode tab 5, a negative electrode tab 6, an electrolyte (not shown), and a reference electrode 7 inside a battery can 2, and a can lid 8. It is the structure sealed with. The gap between the can lid 8 and the battery can 2 is filled with an insulating sealant 9 for the purpose of ensuring the airtightness inside the battery can 2 and ensuring the insulation between the can lid 8 and the battery can 2. . In the case of the secondary battery of the present embodiment, a part (top cap) of the can lid 8 is a positive electrode, and the battery can 2 is a negative electrode. The reference electrode 7 is disposed in the battery can 2 and the can lid 8.

  The battery can 2 has a cylindrical shape with one side closed. Any known material can be used for the battery can 2 as long as it is made of metal. For example, stainless steel or nickel alloy can be used. In the secondary battery 1 of this embodiment, the battery can 2 itself has a polarity (minus). Therefore, the outer surface of the battery can 2 may be covered with an insulating film except for a part for the purpose of preventing a short circuit due to contact between the batteries. A negative electrode tab 6 is connected to the battery can 2.

  The power generation element 3 is a so-called electrode winding body, and is obtained by winding the positive electrode sheet 10 and the negative electrode sheet 11 with the separator 12 interposed therebetween. In some cases, a cylindrical axis is provided at the center of the electrode winding body. The power generation element 3 positive electrode tab 5 and negative electrode tab 6 are connected.

FIG. 3 is an external view of a positive electrode sheet or a negative electrode sheet according to this example. As shown in FIG. 3, the positive electrode sheet 10 is formed by applying a mixture slurry composed of a positive electrode active material, a binder, and a dispersion solution to a strip-shaped positive metal foil 13 to which a positive electrode tab 5 has been welded in advance. The dispersion solution of the application unit 14 is removed by drying, and the positive electrode application unit 14 is further heated and compressed. As the positive electrode metal foil 13, the positive electrode active material, and the binder used for the positive electrode sheet 10, all known materials can be used. For example, an aluminum foil can be used for the positive electrode metal foil, LiNi _0.33 Mn _0.33 Co _0.33 O ₂ can be used for the positive electrode active material, and polyvinylidene fluoride (PVDF) can be used for the binder. In addition, in order to improve electronic conductivity, the conductive support agent which consists of powdery carbon may be added to a mixture slurry.

  The negative electrode sheet 11 has the same shape as the positive electrode sheet 10 shown in FIG. 3 described above, and is a mixture comprising a negative electrode active material and a binder on a strip-shaped negative electrode metal foil 15 to which the negative electrode tab 6 has been welded in advance. The slurry is applied, and thereafter, the dispersion solution of the negative electrode application part 16 is removed by drying, and the negative electrode application part 16 is further heated and compressed. As the negative electrode metal foil 15, the negative electrode active material, and the binder used for the negative electrode sheet 11, all known materials can be used. For example, copper foil can be used for the negative electrode metal foil 15, graphite can be used for the negative electrode active material, and polyvinylidene fluoride (PVDF) can be used for the binder. In addition, in order to improve electronic conductivity, the conductive support agent which consists of powdery carbon may be added to a mixture slurry.

  The separator 12 is used in order to avoid the direct contact between the positive electrode sheet 10 and the negative electrode sheet 11. The separator 12 is sandwiched between the positive electrode sheet 10 and the negative electrode sheet 11, and has a strip shape similar to both sheets. However, the width of the band is wider than the width of the positive electrode sheet 10 and the negative electrode sheet 11. Thereby, when winding an electrode sheet, it can avoid that the positive electrode sheet 10 and the negative electrode sheet 11 which oppose on both sides of the separator 12 contact directly directly. Any known material can be used for the separator 12. For example, a porous sheet obtained by stretching polyethylene (PE), polypropylene (PP), or the like can be used.

  In FIG. 4, the external view of the electric power generation element before inserting in the battery can which concerns on a present Example is shown. The positive electrode tab 5 and the negative electrode tab 6 protrude from both sides of the power generation element 3 wound in a cylindrical shape. The outermost periphery of the power generation element 3 is a separator 12. This configuration can be created by winding the separator 12 continuously without cutting only the separator 12 after the positive electrode sheet 10 and the negative electrode sheet 11 are wound. The reason why the outermost periphery is made of the separator 12 is that when the application part of the metal foil or the active material is exposed, they come into contact with various components inside the battery, and the application part is broken. This is to avoid concerns. Note that the end of the power generation element 3 is stopped with a tape 18 in order to prevent the power generation element 3 wound in a cylindrical shape from loosening. There is a through hole in the center of the power generation element 3, and this through hole is used to insert a welding jig when the negative electrode tab 6 is later welded to the bottom of the battery can 2. Here, the positive electrode tab 5 is welded to a part of the can lid 8, and the negative electrode tab 6 is welded to the can bottom of the battery can 2. Therefore, as described above, a part of the can lid 8 is a positive electrode and the battery can 2 is a negative electrode.

  FIG. 5 is an external view of a reference electrode according to the present embodiment. FIG. 6 is an external view illustrating the configuration of the reference electrode according to the present embodiment. The reference electrode 7 has a substantially strip shape as shown in FIG. One end of the reference electrode 7 is welded to the can lid 8, and the other end is inserted into the gap between the power generation element 3 and the battery can 2. As shown in FIGS. 5 and 6, the reference electrode 7 includes an electrode material 19, a reference electrode tab 20, a separator 21, and a tape 22 that fixes the separator 21.

  The electrode material 19 may be any known material as long as the potential is stable in the environment exposed to the electrolytic solution. As the electrode material 19, for example, lithium metal or the like is used.

  The electrode material 19 is electrically connected to a part of the reference electrode tab 20. The reference electrode tab 20 has a role of bringing the electrode material 19 and the can lid 8 into electrical contact. The characteristics required for the reference electrode tab 20 are such that corrosion is negligible in an environment exposed to the electrolyte, and any known material can be used as long as the characteristics are satisfied. As the reference electrode tab 20, for example, nickel metal or the like is used.

  The separator 21 can be the same as that incorporated in the power generation element 3 and cut into an appropriate size.

  FIG. 6 shows a state where the tape of FIG. 5 is removed and the separator is opened. As shown in FIG. 6, after the electrode material 19 is wound around a part of the reference electrode tab 20, the outside of the wound electrode material 19 is covered with a separator 21, and the end of the separator 21 is fixed with a tape 22. Thus, the reference electrode 7 is obtained. In order to stably contact the reference electrode tab 20 and the electrode material 19, the electrode material 19 is preferably crushed after the electrode material 19 is wound around the reference electrode tab 20.

FIG. 7 is a partially enlarged view of FIG. 2 for explaining the cross-sectional structure of the can lid according to the present embodiment.
The can lid 8 is integrated with the battery can 2 by caulking. The gap between the can lid 8 and the battery can 2 is filled with an insulating sealant 9 for the purpose of ensuring the airtightness inside the battery can 2 and ensuring the insulation between the can lid 8 and the battery can 2. Yes. As shown in FIG. 7, the can lid 8 has a structure in which the inner pressure sensitive part 24 is surrounded by an outer frame structure 25.

  The internal pressure sensitive part 24 is electrically connected to the power generation element 3 via the positive electrode tab 5. The internal pressure sensitive unit 24 is configured so that a charge / discharge current normally flows. However, when the internal pressure of the first internal pressure sensitive plate 27 increases, the internal pressure of the battery increases when the internal pressure of the battery increases due to overcharge or the like. In addition, it has a role of interrupting current.

The outer frame structure 25 is electrically connected to the electrode material 19 provided in the reference electrode 7 through the reference electrode tab 20. The outer frame structure 25 is used as a bypass for reading the potential of the reference electrode 7 from the outside of the battery.
As shown in the figure, the internal pressure sensitive part 24 and the outer frame structure 25 are separated by an insulating member or space, and both are electrically separated. The outer frame structure 25 has an outer frame structure exposed portion 26. The outer frame structure exposed portion 26 reads the potential of the reference electrode 7 by connecting the reference electrode external circuit 34 to the outer frame structure exposed portion 26 formed so as to surround the top cap exposed portion 41. Can do.

  Here, a method for producing a can lid will be described with reference to FIG. FIG. 8 is an exploded view illustrating the configuration of the can lid according to the present embodiment.

  First, the first internal pressure sensitive plate 27, the circular packing 28 made of polypropylene, which is an insulating member, and the second internal pressure sensitive plate 29 are overlapped. In the circular packing 28, the first internal pressure sensitive plate 27 and the second internal pressure sensitive plate 29 come into electrical contact after the battery internal pressure rises due to overcharging or the like and the first internal pressure sensitive plate 27 is reversed to the outside of the battery. It has a role to avoid that.

  Next, the first internal pressure sensitive plate 27 and the second internal pressure sensitive plate 29 are brought into contact with each other in the vicinity of the center, the contacted portion is laser-welded, and the first internal pressure sensitive plate 27 and the second internal pressure sensitive plate 29 are integrated. Thus, the internal pressure sensitive part 24 is produced. By producing the internal pressure sensitive part 24 in this way, the first internal pressure sensitive plate 27 can be reliably reversed to the outside of the battery when the battery internal pressure rises due to overcharging or the like.

  Next, on the outer frame structure 25, one of which is bent inward, a polypropylene circular packing 30 as an insulating member, an internal pressure sensitive portion 24, a top cap 31, and a polypropylene circular packing 32 as an insulating member are laminated in this order. Then, the outer frame structure 25 is caulked, the inner pressure sensitive part 24, the top cap 31, and the circular packing 32 made of polypropylene as an insulating member are fixed, and the can lid 8 is obtained.

  The circular packing 30 insulates the outer frame structure 25 having the potential of the reference electrode 7 from the internal pressure sensitive part 24 having the positive electrode potential.

  The top cap 31 is used as a bypass for reading the positive electrode potential from the outside of the battery. The top cap 31 is connected to the positive electrode tab 5 via the internal pressure sensitive part 24. The top cap 31 has a top cap exposed portion 41.

  The circular packing 32 insulates the outer frame structure 25 having the potential of the reference electrode 7 from the top cap 31 having the positive electrode potential.

  FIG. 9 shows the appearance of the can lid 8. It can be seen that the outer frame structure 25 is formed in an annular shape around the top cap 31. The reference electrode tab 20 is later welded to the outer frame structure 25. The top cap 31 is made of metal, and the top cap 31 -the internal pressure sensitive portion 24 -the positive electrode tab 5 -the power generation element 3 is electrically connected, and the top cap 31 becomes a positive electrode. For example, aluminum having a thickness of 0.3 mm is used for the outer frame structure 25, and aluminum having a thickness of 0.1 mm is used for the first internal pressure sensitive plate 27 and the second internal pressure sensitive plate 29. For the top cap 31, for example, a cold rolled steel strip with a thickness of 0.3 mm is used.

  Here, since the can lid 8 has a disk shape, once it is in the state of a cylindrical secondary battery, it cannot be known from the appearance where the reference electrode 7 is inside the battery. Therefore, for example, as shown in FIG. 10, a position of the reference electrode 7 may be indicated by inserting a notch 33 into a part of the outer frame structure 25.

Next, a method for clarifying the potentials of the positive electrode and the negative electrode based on the potential of the reference electrode 7 will be described.
FIG. 11 is an external view showing the relationship between the cylindrical secondary battery and the battery control board according to the present embodiment.
In order to clarify the potential of the positive electrode and the negative electrode, the following procedure is taken.

  (1) The reference electrode external circuit 34 is connected to the outer frame structure exposed portion 26 of the outer frame structure 25, and the positive electrode external circuit 35 and the battery can 2 ( A negative pole external circuit 36 is connected to the negative pole). At this time, the respective potentials obtained by the reference pole external circuit 34, the plus pole external circuit 35, and the minus pole external circuit 36 are collected on the battery control board 37.

  (2) Read the potential difference V1 between the reference pole external circuit 34 and the plus pole external circuit 35, and read the potential difference V2 between the reference pole external circuit 34 and the minus pole external circuit 36, respectively. In this embodiment, since the electrode material 19 of the reference electrode 7 is lithium metal, V1 obtained in this way is the potential of the positive electrode based on the lithium metal, and V2 is the potential of the negative electrode based on the lithium metal.

As described above, by applying this embodiment, unlike the case where the metal case potential (battery can) is used as the reference electrode, in this embodiment, the potential of the reference electrode 7 is set inside the can lid 8. Since there is a portion (outer frame structure 25) to be included, a portion having the potential of the reference electrode 7 of a certain battery and a portion having the potential of the reference electrode 7 of a certain battery different from that are spatially separated.
As a result, even if foreign matters such as water droplets are mixed in, it is difficult to form a short circuit, so that the potential of the reference electrode 7 is difficult to change, and the potential management of the reference electrode 7 can be easily performed. Further, the positive electrode potential and the negative electrode potential can be detected with high accuracy.

  Although the present invention has been described with reference to the embodiments, the secondary battery according to the present invention is mounted on an in-vehicle battery system applied to a hybrid vehicle using a motor as a drive source, a zero emission electric vehicle, or the like. It can be used as a secondary battery. Moreover, the battery system carrying the secondary battery of this invention can be used without being limited to the said use. The battery system equipped with the secondary battery of the present invention is used as a power storage system that charges and stores a battery with electric power generated by solar power generation or wind power generation, regardless of whether it is for home use, business use, or industrial use. It can also be used as a power storage system that charges a battery using midnight power at night or stores it, or as a power storage system that can be used outside the ground, such as a space station, spacecraft, or space base. it can. Furthermore, a battery system equipped with the assembled battery of the present invention is applied for industrial use such as medical equipment, construction machines, power storage systems, elevators, unmanned mobile vehicles, and for mobile objects such as golf carts and turret cars. Can do.

DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Battery can 3 Electric power generation element 4 Insulation sheet 5 Positive electrode tab 6 Negative electrode tab 7 Reference electrode 8 Can lid 9 Sealant 10 Positive electrode sheet 11 Negative electrode sheet 12 Separator 13 Positive electrode metal foil 14 Positive electrode application part 15 Negative electrode metal foil 16 Negative electrode coating part 17 Electrode winding body 18 Tape 19 Electrode material 20 Reference electrode tab 21 Separator 22 Tape 24 Internal pressure sensitive part 25 Outer frame structure 26 Outer frame structure exposed part 27 First internal pressure sensitive plate 28 Circular packing 29 Second internal pressure Sensing plate 30 Circular packing 31 Top cap 32 Circular packing 33 Notch 34 Reference pole external circuit 35 Positive pole external circuit 36 Negative pole external circuit 37 Battery control board 41 Top cap exposed portion

Claims (2)

Power generation elements,
A positive electrode tab and a negative electrode tab connected to the power generation element;
A battery can that houses the electrode group, the positive electrode tab, and the negative electrode tab;
A can lid for sealing the battery can;
A cylindrical secondary battery having the battery can and a reference electrode disposed in the can lid,
The can lid has an internal pressure sensitive part, an outer frame structure, and a top cap,
The reference electrode has a reference electrode tab and an electrode material;
The outer frame structure is connected to the electrode material via the reference electrode tab,
Via the internal pressure sensitive part, the positive electrode tab is connected to the top cap,
The battery can is connected to the negative electrode tab;
The top cap has a top cap exposed portion;
The outer frame structure has an outer frame structure exposed portion,
The cylindrical secondary battery is formed so that the outer frame structure exposed portion surrounds the top cap exposed portion. In claim 1,
The outer frame structure is a cylindrical secondary battery having a notch.