JP2019145349A - Lithium battery - Google Patents

Abstract

To provide a cylindrical lithium battery excellent in safety, discharge characteristics, and productivity.SOLUTION: A lithium battery includes: a bottomed cylindrical battery can which has an opening at one end; a hollow cylindrical positive electrode mixture, a separator, a negative electrode, and an electrolyte which are housed in the battery can; a sealing body which seals the opening of the battery can; and a rod-like negative electrode collector which is protrudingly fixed to a negative electrode terminal plate. The negative electrode, which is made of a tabular member obtained by molding lithium metal or a lithium alloy, is arranged inside the positive electrode mixture so as to be wound around the negative electrode collector. The tabular member is spirally wound around the negative electrode collector. An inner peripheral surface on at least an outermost peripheral end of the tabular member comes into contact with an outer peripheral surface of an inner layer directly under the outermost peripheral end of the tabular member.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lithium battery using lithium metal or a lithium alloy as a negative electrode.

  Patent Document 1 describes a bobbin-type lithium primary battery using lithium metal or a lithium alloy as a negative electrode. A bobbin-type lithium primary battery has a hollow cylindrical negative electrode lithium in a hollow cylindrical battery can whose opening is sealed by a sealing body that also serves as a negative electrode terminal plate, and a separator inside the hollow cylindrical positive electrode mixture. The negative electrode lithium is made of a thin metal plate integrally formed with a negative electrode lead portion extending upwardly from the upper edge of the current collecting region contacting the inner surface. A negative electrode current collector is attached, and the negative electrode lead portion has a tip end side connected to the lower surface of the sealing body, and a strength reduction portion having a lower strength than other regions is formed by machining on the way of extension.

JP 2017-147069 A

  In order to enhance safety against forced discharge (including overdischarge) and abnormal charge mode, the lithium battery is required to have a high area occupation ratio of the negative electrode current collector with respect to the negative electrode and the surface area of the positive electrode. Moreover, when using a thin plate-like negative electrode current collector like the bobbin-type lithium primary battery described in Patent Document 1, it is necessary to increase the inner diameter of the negative electrode in accordance with the outer diameter of the negative electrode current collector. Since it is maintained until the end of discharge, it is necessary to increase the distance between the electrodes in order to reduce the risk of penetrating dendrites (dendritic lithium metal) through the separator, which affects the discharge performance. Moreover, in order to prevent the risk of internal ignition due to the cutting of the negative electrode material, it is also necessary to ensure the current collection efficiency over the entire negative electrode current collector.

  This invention is made | formed in view of such a background, and it aims at providing the cylindrical lithium battery excellent in safety | security, discharge characteristics, and productivity.

  The present invention for achieving the above object is a lithium battery, a bottomed cylindrical battery can opened at one end, a hollow cylindrical positive electrode mixture, a separator, a negative electrode, And an electrolyte, a sealing body that seals the opening of the battery can, and a rod-shaped negative electrode current collector that is erected and fixed to the sealing body, and the negative electrode is a plate formed of lithium metal or a lithium alloy And is disposed inside the positive electrode mixture in a state of being wound around the negative electrode current collector.

  Another aspect of the present invention is the above lithium battery, wherein the plate-like member is spirally wound around the negative electrode current collector, and at least the outermost peripheral end portion of the plate-like member is included. The peripheral surface is in contact with the outer peripheral surface of the inner layer immediately below the outermost peripheral end portion of the plate-like member.

  Another aspect of the present invention is the lithium battery, wherein at least one of the battery can, the sealing body, and the negative electrode current collector is configured using a member of a cylindrical alkaline battery.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  According to the present invention, a cylindrical lithium battery excellent in safety, discharge characteristics, and productivity can be provided.

It is a longitudinal cross-sectional view in the case where the extending direction of the cylindrical axis of the lithium battery is the vertical (vertical) direction. It is a figure explaining the structure and manufacturing method of the negative electrode of a lithium battery. (A) is a figure which shows the plate-shaped member and negative electrode collector before winding a plate-shaped member, (b) is winding the plate-shaped member around the rod-shaped part of a negative electrode collector. It is a figure which shows the state in the middle, (c) is a figure which shows the state of the plate-shaped member and negative electrode collector after finishing winding a plate-shaped member around the rod-shaped part of a negative electrode collector. It is sectional drawing obtained by cut | disconnecting the structure of the negative electrode electrical power collector and negative electrode of FIG.2 (c) by the A-A 'line | wire of FIG.2 (c). It is a block diagram of the negative electrode and negative electrode collector of the conventional lithium battery.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted.

  FIG. 1 shows a configuration of a bobbin-type lithium primary battery (hereinafter referred to as a lithium battery 1) shown as an embodiment. This figure is a longitudinal sectional view when the extending direction of the cylindrical shaft 50 of the lithium battery 1 is the vertical (vertical) direction. A lithium battery 1 shown in the figure includes a power generation element in a bottomed cylindrical battery can 2 made of a conductor such as metal, and the opening of the battery can 2 is a negative terminal plate 7 made of a conductor such as metal. Manufactured by sealing.

  As shown in the figure, a lithium battery 1 includes a battery can 2, a positive electrode mixture 3 formed by forming a positive electrode active material such as manganese dioxide into a hollow cylindrical shape together with a conductive aid such as graphite (carbon black), metallic lithium Or a negative electrode 4 made of a lithium alloy, a bottomed cylindrical separator 5, a negative electrode current collector 6 made of a metal (brass or the like) conductor, a negative electrode terminal plate 7, and a sealing gasket 10 made of a resin such as nylon or polyolefin. .

  The battery can 2 functions as a battery case and a positive electrode current collector. A positive electrode terminal 8 is formed on the battery can 2 so as to protrude downward. The battery can 2 contains a positive electrode mixture 3, a separator 5, and a negative electrode 4, and is filled with an electrolyte solution (not shown). As shown in the figure, the negative electrode 4 is disposed inside the positive electrode mixture 3 via a separator 5. As will be described later, the negative electrode 4 includes a plate-like member 41, and the plate-like member 41 is housed in the battery can 2 while being wound around the negative electrode current collector 6 in a spiral shape (spiral shape). Is done. In the figure, the configuration of the negative electrode 4 is simplified.

  As shown in the figure, the negative electrode terminal plate 7 includes a circular flat plate portion 71 and a flange portion 72 formed around the flat plate portion 71. The negative electrode terminal plate 7 constitutes a sealing body 20 that seals the can of the battery can 2 together with the sealing gasket 10. The negative electrode current collector 6 includes a cylindrical rod-shaped portion 61 having a length that is at least half the length of the battery can 2 in the longitudinal direction, and a disk-shaped portion 62 formed at the upper end of the rod-shaped portion 61.

  As shown in the figure, the upper surface of the disk-shaped portion 62 is electrically connected to the lower surface of the negative electrode terminal plate 7 by welding or the like, so that the rod-shaped portion 61 extends from the center of the flat plate portion 71 of the negative electrode terminal plate 7. The battery can 2 is erected and fixed in the longitudinal direction.

  FIG. 2 is a diagram illustrating the configuration and manufacturing method of the negative electrode 4 of the lithium battery 1 of the present embodiment. As shown in FIG. 2A, the lithium battery 1 of the present embodiment uses a planar rectangular plate-like member 41 obtained by rolling metal lithium, a lithium alloy, or the like as the material of the negative electrode 4. Then, as shown in FIGS. 2B and 2C, the negative electrode 4 is formed by winding the plate-like member 41 around the rod-like portion 61 of the negative electrode current collector 6 in a spiral shape (spiral shape). Yes.

  The planar shape of the plate-like member 41, the thickness of the plate-like member 41, and the number of times of winding the plate-like member 41 around the rod-like portion 61 of the negative electrode current collector 6 are the safety of the lithium battery 1, the discharge characteristics, Further, it is set based on the viewpoint of productivity, the size of the lithium battery 1, the shape and size of the positive electrode mixture 3, the diameter of the negative electrode current collector 6, and the like.

  The diameter of the rod-shaped portion 61 of the negative electrode current collector 6 is set to a size range in which the plate-like member 41 can be wound, and in consideration of ease of welding to the negative electrode terminal plate 7 and securing of strength. Is set. For example, in the case of an AA size lithium battery 1, the diameter is about 1 mm, for example.

  From the viewpoint of improving safety against forced discharge (including overdischarge) and abnormal charge mode, the negative electrode 4 covers at least the entire portion of the rod-shaped portion 61 of the negative electrode current collector 6 facing the positive electrode mixture 3. The negative electrode current collector 6 is preferably wound around. From the viewpoint of preventing disconnection of the negative electrode 4 at the time of overdischarge, which causes internal ignition and the like, the negative electrode 4 is just the entire portion of the rod-shaped portion 61 of the negative electrode current collector 6 facing the positive electrode mixture 3. It is preferable to wind it around the negative electrode current collector 6 so as to cover it. In addition, by making the rod-shaped portion 61 of the negative electrode current collector 6 longer, the area occupation ratio of the negative electrode current collector 6 with respect to the surface areas of the negative electrode and the positive electrode can be increased, and safety against forced discharge (including overdischarge) and abnormal charge modes is achieved. Can increase the sex.

  FIG. 3 is a cross-sectional view obtained by cutting the configurations of the negative electrode current collector 6 and the negative electrode 4 of FIG. 2C along the line A-A ′ of FIG. As shown in the figure, in this example, a plate-like member 41 is wound around the periphery of the negative electrode current collector 6 about two rounds. As shown in the figure, there is a gap S between the layers of the plate-like member 41 (negative electrode 4) wound around the negative electrode current collector 6, and this gap S is a contact between the negative electrode 4 and the electrolyte. Contributes to increased area.

  As shown in the figure, at least the inner peripheral surface of the outermost peripheral end portion 42 of the plate-like member 41 is in contact (electrically connected) with the outer peripheral surface of the inner layer immediately below the plate-like member 41. preferable. By doing so, for example, even when the plate-like member 41 is cut halfway due to overdischarge or the like, a part of the cut plate-like member 41 is electrically cut from the negative electrode current collector 6. The risk of internal ignition caused by the cutting of the negative electrode 4 can be reduced.

  As described above, the lithium battery 1 of the present embodiment includes the battery can 2, the positive electrode mixture 3, the separator 5, the negative electrode current collector 6, and the sealing body 20 (the negative electrode terminal plate 7 and the sealing gasket 10). A member (component) used for manufacturing a cylindrical alkaline battery can be used (utilized). Therefore, the material cost can be reduced and the manufacturing process can be simplified, and the inexpensive lithium battery 1 can be provided.

  FIG. 4 is a configuration diagram of a negative electrode 4 ′ and a negative electrode current collector 6 ′ of a conventional lithium battery described in Patent Document 1 shown as a comparative example. As can be seen from the figure, in the case of a conventional lithium battery, the inner diameter of the negative electrode 4 ′ needs to be matched with the outer diameter of the negative electrode current collector 6 ′, and this shape is maintained until the end of discharge, and dendrites (dendritic shape) In order to reduce the risk of metal lithium) penetrating the separator, it is necessary to increase the distance between the electrodes, which affects the discharge performance. Further, in the case of a conventional lithium battery, it is necessary to devise a crimping surface in order to ensure the crimping strength between the negative electrode 4 ′ and the negative electrode current collector 6 ′, and the process may be complicated, resulting in poor current collection. There is.

  On the other hand, in the case of the lithium battery 1 of the present embodiment having the configuration shown in FIG. 3, the distance (interval) between the negative electrode 4, the separator 5, and the positive electrode mixture 3 as the negative electrode 4 (plate-like member 41) decreases. ) Will spread. Therefore, the risk of penetration of the separator caused by reversal overdischarge or charging due to misuse when batteries having different remaining capacities are connected is reduced. In addition, because of the structure, it is easy to ensure the distance between the electrodes, and it is easy to ensure high load pulse characteristics. In addition, when the negative electrode current collector 6 is wound around the negative electrode 4, it is easy to secure the pressure bonding strength between the negative electrode 4 and the negative electrode current collector 6, and it is difficult to cause current collection failure.

  Instead of winding the negative electrode 4 (plate-like member 41) around the negative electrode current collector 6 as in the present embodiment, the negative electrode current collector 6 is inserted into the negative electrode material (metallic lithium or lithium alloy). Although it is conceivable to pierce (stab), there is a risk of strength when the negative electrode current collector 6 is inserted against the drag of the negative electrode material, and manufacturing is particularly difficult when the battery is tall. Further, in the case of the insertion method, it is difficult to secure a contact area between the negative electrode material and the electrolytic solution. As a result, it is necessary to widen the distance between the electrodes, which affects the high load pulse characteristics.

= Performance verification =
In order to verify the performance of the lithium battery 1 having the above-described configuration, the bobbin-type lithium primary battery (hereinafter referred to as “Example”) having the cross-sectional structure shown in FIG. 3 and the cross-sectional structure shown in FIG. A bobbin-type lithium primary battery (hereinafter referred to as “comparative example”) was prepared and tested. All of the prototype bobbin-type lithium primary batteries were AA size (14.5 mm in diameter and 50.0 mm in height).

表１に示すように、比較例についてはモードＤにおいて異常を示すものが存在するが、実施例の場合はモードＡ〜Ｄの全てについて異常を示すものは存在しなかった。 <Safety test>
Table 1 shows the results of testing for safety. Details of the modes A to D shown in Table 1 are shown in Table 2. The number of tests (number of samples) was set to 5 for both the examples and comparative examples.

As shown in Table 1, there were those showing an abnormality in mode D for the comparative example, but none of the modes A to D showed an abnormality in the example.

表３に示すように、実施例について比較例と同等の放電性能が得られることがわかった。 <Discharge performance test>
Table 3 shows the results of tests conducted on the discharge performance. Tests were conducted for each of continuous discharge characteristics (continuous discharge at 23 ° C. and 1 kΩ load) and pulse discharge specification (23 ° C., ON every second (on-state current 40 mA)). In addition, the numerical value in a table | surface is a relative value when the discharge characteristic of a comparative example is set to 100.

As shown in Table 3, it was found that the discharge performance equivalent to that of the comparative example was obtained for the example.

表４に示すように、実施例は比較例よりも良好なパルス特性が得られた。これは実施例のほうが負極と電解液との間の接触面積が大きく、パルス負荷時の閉路電圧降下が小さくなるからであると考えられる。 In addition to the above comparative example, a bobbin-type lithium primary battery of a comparative example having a structure in which the negative electrode current collector 6 is further inserted (pierced) into the negative electrode material (the other structures are the same as those in the example) was manufactured and discharged. The performance was verified. Table 4 shows the results. The numerical values in the table are relative values when the discharge characteristic of the comparative example is 100.

As shown in Table 4, the example obtained better pulse characteristics than the comparative example. This is considered to be because the contact area between the negative electrode and the electrolytic solution is larger in the example, and the closed circuit voltage drop at the time of pulse load is smaller.

表５に示すように、実施例はいずれのサンプルについても比較例と同等の高温保存特性（耐漏液性）であった。 <High temperature storage characteristics (leakage resistance) test>
Table 5 shows the results of testing for high temperature storage characteristics (leakage resistance). The number of tests (number of samples) was set to 5 for both the examples and comparative examples.

As shown in Table 5, the Examples had the same high-temperature storage characteristics (leakage resistance) as the comparative examples for all the samples.

= Effect =
As described above, according to the lithium battery 1 of the present embodiment, the area occupation ratio of the negative electrode current collector 6 with respect to the surface areas of the negative electrode 4 and the positive electrode (battery can 2) can be ensured. In addition, according to the lithium battery 1 of the present embodiment, the distance between the negative electrode 4 and the separator 5 and the positive electrode mixture 3 increases as the negative electrode 4 decreases, so that the reversal when batteries having different remaining capacities are connected to each other. The risk of penetration of the separator caused by charging due to overdischarge or misuse can be reduced.

  Moreover, the lithium battery 1 of this embodiment is easy to ensure the distance between the electrodes, and the negative electrode 4 and the electrolyte solution are formed by the gap S existing between the layers of the plate-like member 41 (negative electrode 4) wound around the negative electrode current collector 6. Can be ensured, and the high-load pulse characteristics are not impaired.

  Moreover, since the lithium battery 1 of this embodiment is a system which winds around the negative electrode 4 around the negative electrode collector 6, it is easy to ensure the crimping | compression-bonding strength between the negative electrode 4 and the negative electrode collector 6, and current collection defect arises. Hateful.

  Moreover, the lithium battery 1 of this embodiment can use (utilize) the member (component) used for manufacture of a cylindrical alkaline battery as the structural member. Therefore, the material cost can be reduced and the manufacturing process can be simplified, and the inexpensive lithium battery 1 can be provided.

  In addition, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Lithium battery, 2 Battery can, 3 Positive electrode mixture, 4 Negative electrode, 41 Plate-shaped member, 42 Outermost peripheral edge part, 5 Separator, 6 Negative electrode current collector, 61 Rod-shaped part, 62 Disc-shaped part, 7 Negative electrode terminal board 71 Flat plate part 72 Flange part 10 Sealing gasket 20 Sealing body

Claims (3)

A bottomed cylindrical battery can with one end open;
A hollow cylindrical positive electrode mixture, a separator, a negative electrode, and an electrolyte solution housed in the battery can,
A sealing body for sealing the opening of the battery can;
A rod-shaped negative electrode current collector standingly fixed to the sealing body;
Including
The negative electrode is composed of a plate-shaped member formed of lithium metal or a lithium alloy, and is disposed inside the positive electrode mixture in a state of being wound around the negative electrode current collector. Lithium battery. The plate-like member is wound in a spiral around the negative electrode current collector,
The inner peripheral surface of at least the outermost peripheral end portion of the plate-shaped member is in contact with the outer peripheral surface of the inner layer immediately below the outermost peripheral end portion of the plate-shaped member. Lithium battery. The lithium battery according to claim 1, wherein at least one of the battery can, the sealing body, and the negative electrode current collector is configured using a cylindrical alkaline battery member.

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