JP3876934B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery including a wound power generation element in which a positive electrode and a negative electrode are wound with a separator interposed therebetween.
[0002]
[Prior art]
Secondary devices using non-aqueous electrolytes (organic electrolytes) with high energy density and long charge / discharge cycle life are required for drive devices such as electric vehicles and portable electronic devices such as mobile phones because high rate discharge performance is required. Batteries are widely used. A nonaqueous electrolyte secondary battery is generally configured as a lithium secondary battery using a lithium-based active material for a positive electrode and a negative electrode. In this non-aqueous electrolyte secondary battery, since the electrical resistance of the non-aqueous electrolyte is significantly higher than that of the aqueous electrolyte, it is necessary to increase the area of the positive electrode and the negative electrode to increase the opposing area of the electrodes. Therefore, in general, as shown in FIG. 6, the non-aqueous electrolyte secondary battery is a strip-shaped insulator including a strip-shaped positive electrode 3 and a negative electrode 4 in which a positive electrode active material and a negative electrode active material are supported on a sheet-shaped core material. There are many winding type elements that constitute the power generating element 1 by winding through the separator 5. FIG. 6 shows the case where the power generating element 1 is formed in a cylindrical shape, but it may be formed in an oval shape.
[0003]
As shown in FIG. 7, the wound power generation element 1 has current collector plates 6 and 7 welded to upper and lower end faces, and a positive electrode 3 and a negative electrode 4 are connected to the current collector plates 6 and 7, respectively. Collect current. The power generating element 1 is housed in the battery container 10, and the current collector plates 6, 7 are connected to the container lid 10 b and the container body 10 a that are the positive and negative terminals of the battery container 10, respectively. Use batteries. Here, in the conventional nonaqueous electrolyte secondary battery, there is a case where the central portion of the winding of the power generating element 1 is left hollow, and as shown in FIG. 7, a metal shaft core used as a winding shaft. 2 may be left as it is, or a metal shaft 2 prepared separately after winding may be inserted. Further, when the shaft core 2 is placed at the center of winding of the power generating element 1, the shaft core 2 is not fixed to the battery container 10.
[0004]
[Problems to be solved by the invention]
However, a large capacity non-aqueous electrolyte secondary battery of 100 to 400 Wh class used for an electric vehicle or the like generates a large amount of heat when discharging a large current. In addition, particularly in the central portion of the power generation element 1, since the periphery is surrounded by the positive and negative electrodes 3 and 4 and the separator 5, the heat generated here is hardly released to the outside through the battery container 10. In addition, when there is a metal shaft core 2 at the center of the power generating element 1, the heat generated here is transferred to the shaft core 2 with good thermal conductivity, but this shaft core 2 is fixed. Therefore, heat could not be sufficiently transmitted to the battery container 10 and improvement of the heat dissipation effect could not be expected. For this reason, in the conventional nonaqueous electrolyte secondary battery, since the heat dissipation efficiency of the center part of the power generation element 1 is poor, there is a problem that the battery temperature may rise abnormally.
[0005]
Further, when the non-aqueous electrolyte secondary battery is used for an electric vehicle or the like, it is often subjected to repeated vibrations, impacts, and the like. However, when the metal shaft core 2 is placed at the center of the power generating element 1, the shaft core 2 may move or jump in the battery container 10 due to vibration or impact. For this reason, in the conventional nonaqueous electrolyte secondary battery, when the metal shaft core 2 is placed, the shaft core 2 is subjected to vibration or the like and damages the separator 5 or the like. In the worst case, a short circuit accident occurs. There was also a problem of generating
[0006]
The present invention has been made in view of such circumstances, and by disposing a metal shaft core at the center of the power generation element and fixing or sandwiching the shaft core to the battery container, the center of the power generation element is provided. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that efficiently dissipates the heat generated in step 1 and that is not damaged even when subjected to vibration or the like.
[0007]
[Means for Solving the Problems]
That is, in order to solve the above-mentioned problem, the invention according to claim 1 is a non-aqueous electrolyte secondary battery in which a power generation element in which a belt-like positive electrode and a negative electrode are wound via a belt-like separator is housed in a battery container. In addition, a metal shaft core is disposed in the central portion of the winding of the power generating element, and at least one of the upper and lower ends of the metal shaft core is directly or via an attachment member, A current collector plate is disposed on the upper and lower end surfaces of the power generation element, and is fixed to the bottom surface.
[0008]
According to the first aspect of the present invention, since the metal shaft core is disposed at the central portion of the winding of the power generation element and is fixed to the battery container, the heat generated by the power generation element is excellent in thermal conductivity. The heat is efficiently transmitted to the battery case through the shaft core (in some cases through the attachment member). In addition, since the metal shaft core is fixed to the battery container, there is no possibility that the separator or the like may be damaged by moving or jumping inside the battery even when the battery is subjected to vibration or impact.
[0009]
According to a second aspect of the present invention, there is provided a nonaqueous electrolyte secondary battery in which a power generating element in which a belt-like positive electrode and a negative electrode are wound via a belt-like separator is housed in a battery container. A metal shaft core is disposed at the center, and upper and lower ends of the metal shaft core are abutted and sandwiched between the inner upper surface and the bottom surface of the battery container directly or via an attachment member , Current collectors are arranged on the upper and lower end faces .
[0010]
According to the second aspect of the present invention, since the metal shaft core is disposed at the center of the winding of the power generation element and the upper and lower ends are brought into contact with the battery container, the heat generated by the power generation element is thermally conducted. It is efficiently transmitted to the battery case through the shaft core excellent in performance (in some cases also through an attachment member) and is radiated. In addition, since the upper and lower ends of the metal shaft core are sandwiched between the battery containers, even if the battery is subjected to vibration or impact, the separator may be damaged due to movement or jumping inside the battery. Disappears.
[0011]
[0012]
Furthermore, the invention described in claim 3 is a non-aqueous electrolyte secondary battery in which a power generation element in which a strip-like positive electrode and a negative electrode are wound in an oval shape through a strip-like separator is housed in a battery container. A metal shaft core having an oval cross section is disposed at the center of the winding of the winding, and protrusions are provided at both ends of the upper end surface of the metal shaft core, and these protrusions are It is brought into contact with the inner upper surface of the battery case via the mounting member, the lower end surface of the shaft core is pressed against the inner bottom surface of the battery case directly or via the lead piece, and the upper and lower end surfaces of the power generation element are connected to the current collector. A board is arranged .
[0013]
According to the third aspect of the present invention, since the metal shaft core having an elliptical cross section is arranged at the center of the winding of the power generating element and is fixed to the battery container, the heat generated in the power generating element Is efficiently transmitted to the battery case through the shaft core having excellent thermal conductivity (and, in some cases, via an attachment member) to be radiated. In addition, since the metal shaft core is fixed to the battery container, there is no possibility that the separator or the like may be damaged by moving or jumping inside the battery even when the battery is subjected to vibration or impact.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 2 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing a structure of a nonaqueous electrolyte secondary battery, and FIG. 2 is a perspective view showing a configuration of a power generating element. . In addition, the same number is attached | subjected to the structural member which has the same function as the prior art example shown in FIGS.
[0015]
As shown in FIG. 2, the nonaqueous electrolyte secondary battery of the present embodiment will be described in the case where the power generating element 1 is wound in a cylindrical shape. The power generating element 1 is configured by winding a strip-like positive electrode 3 and a negative electrode 4 (in the shade of the separator 5 in FIG. 2) around the strip-like separator 5 around an elongated cylindrical shaft core 2. The The shaft core 2 may be inserted after the power generating element 1 is wound. Further, the shape of the shaft core 2 is not necessarily limited to a cylindrical shape, and may be an arbitrary rod shape such as a prismatic shape. In this embodiment, since the shaft core 2 is connected to the negative electrode 4 as will be described later, in consideration of corrosion resistance, a metal made of copper or nickel having excellent thermal conductivity or an alloy mainly composed of these. Is used. However, when the shaft core 2 is connected to the positive electrode 3, the metal core made of aluminum or an alloy mainly composed of aluminum is used, and the specific gravity is made smaller than that of copper or the like to further improve the thermal conductivity. Can be a thing. However, the shaft core 2 only needs to be excellent in thermal conductivity, so that other metal materials can be used. Depending on the type of the nonaqueous electrolyte, any of the positive and negative electrodes 3 and 4 can be used. In the case of being connected to each other, it can be appropriately selected according to the polarity. The positive electrode 3 and the negative electrode 4 are each formed by supporting a positive electrode active material and a negative electrode active material on a band-shaped core material, and the separator 5 is made of a similar band-shaped insulator. The positive electrode 3, the separator 5, and the negative electrode 4 are wound slightly shifted up and down so that only the upper side of the belt 3 of the positive electrode 3 protrudes from the upper end side of the power generation element 1, and the negative electrode 4 is protruded from the lower end side. Only the lower side of the belt is projected.
[0016]
Current collector plates 6 and 7 are disposed on the upper and lower end faces of the power generation element 1 and are connected to the upper side of the positive electrode 3 protruding to the upper end side and the lower side of the negative electrode 4 protruding to the lower end side by laser welding. Accordingly, the wound belt-like positive electrode 3 is collected by the current collector plate 6 on the upper end side, and the negative electrode 4 is collected by the current collector plate 7 on the lower end side. A spring 9 is fitted into the upper end of the shaft core 2 disposed at the center of the power generating element 1 through an insulating cap 8. Since the spring 9 uses a metal compression coil spring which is a conductor, an insulating cap 8 is required for insulation from the shaft core 2. The cap 8 can also be disposed on the upper side of the spring 9.
[0017]
As shown in FIG. 1, the nonaqueous electrolyte secondary battery of the present embodiment houses the power generating element 1 in a battery container 10. The battery container 10 includes a container body 10a made of a cylindrical conductor whose upper surface is opened, and a container lid 10b made of a disk-shaped conductor attached to the upper surface of the container body 10a via an insulator. Is done. The current collector plate 6 on the upper end side of the power generation element 1 housed in the battery container 10 is connected to the back surface of the container lid 10b via a lead piece or the like. Therefore, the protrusion protruding from the center of the container lid 10b becomes the positive electrode terminal of the nonaqueous electrolyte secondary battery. Further, the shaft core 2 protruding from the upper end side of the power generating element 1 is brought into contact with the back surface of the protrusion of the container lid 10 b via the cap 8 and the spring 9. The current collector plate 7 on the lower end side of the power generating element 1 is connected to the inner bottom surface of the container body 10a through a lead piece or the like. Accordingly, the bottom surface of the container main body 10a serves as the negative electrode terminal of the nonaqueous electrolyte secondary battery. Further, the shaft core 2 protruding from the lower end side of the power generating element 1 is urged by the compressed spring 9, and the lower end surface is pressed against the inner bottom surface of the container body 10a. In this case, however, the lower end surface of the shaft core 2 may come into contact with the inner bottom surface of the container body 10a via a lead piece or the like connecting the current collector plate 7 on the lower end side, as shown in FIG.
[0018]
In the case of the present embodiment, the shaft core 2 is in contact with the bottom surface of the container body 10a serving as the negative electrode terminal and connected to the negative electrode 4 as described above, but the cap 8 and the spring 9 are connected to the shaft core 2. If it arrange | positions at a lower end side, it can contact | abut to the back surface of the protrusion of the container lid | cover 10b used as a positive electrode terminal, and can be connected to the positive electrode 3. FIG. In this case, aluminum or the like can be used as the shaft core 2 as described above.
[0019]
In the non-aqueous electrolyte secondary battery having the above-described configuration, even when a large amount of heat is generated during discharge of a large current, the heat at the center of the power generating element 1 is transmitted through the shaft core 2 having excellent thermal conductivity. Since it is conducted to 10a and quickly radiated to the outside, an increase in battery temperature can be suppressed. For example, when compared with a conventional non-aqueous electrolyte secondary battery having the same capacity as that of the present embodiment, the battery temperature could be reduced by about 20%. Even when the cap 8 and the spring 9 are arranged on the lower end side of the shaft core 2, the heat is conducted to the container lid 10b with which the upper end surface of the shaft core 2 abuts and this heat is quickly radiated to the outside. When aluminum or the like is used for the shaft core 2 in this way, the thermal conductivity is further improved and the heat dissipation efficiency is improved, and the weight of the nonaqueous electrolyte secondary battery is suppressed by reducing the weight of the shaft core 2. can do.
[0020]
Further, when the non-aqueous electrolyte secondary battery having the above-described configuration is used in an electric vehicle or the like, it is often subjected to repeated vibrations, impacts, and the like. Therefore, there is no risk of damaging the separator 5 or the like by moving or jumping inside the battery. In addition, in the present embodiment, the shaft core 2 is clamped by the bias of the spring 9, so even when it receives vibrations, the vibrations can be absorbed and the shaft core 2 can be held stably and securely. Can be made.
[0021]
3 to 4 show a second embodiment of the present invention, FIG. 3 is a longitudinal sectional view showing the structure of a nonaqueous electrolyte secondary battery, and FIG. 4 is a perspective view showing the configuration of a power generating element. . In addition, the same number is attached | subjected to the structural member which has the same function as 1st Embodiment shown in FIGS. 1-2, and description is abbreviate | omitted. As shown in FIG. 4, the nonaqueous electrolyte secondary battery of the present embodiment will be described when the power generating element 1 is wound in an oval shape. This power generating element 1 has a strip-like positive electrode 3 and a negative electrode 4 (in the shade of the separator 5 in FIG. 4) with a strip-like separator 5 extending around a plate-like shaft core 2 having an elliptical cross section. It is configured by winding in a circle. The shaft core 2 can also be inserted after the power generating element 1 is wound. Cylindrical protrusions 2 a are provided at both ends of the upper end surface of the shaft core 2. The material of the shaft core 2 is the same as that of the first embodiment. Also, the positive electrode 3, the negative electrode 4, and the separator 5 are the same as those in the first embodiment, and are similarly wound up and down.
[0022]
Current collector plates 6 and 7 are disposed on the upper and lower end faces of the power generating element 1 and are connected to the positive electrode 3 and the negative electrode 4, respectively, as in the first embodiment. In addition, springs 9 are fitted into two protrusions 2 a on the upper end surface of the shaft core 2 disposed at the center of the power generating element 1 via insulating caps 8. These cap 8 and spring 9 may be the same as those in the first embodiment.
[0023]
As shown in FIG. 3, the nonaqueous electrolyte secondary battery of the present embodiment houses the power generating element 1 in a battery container 10. The battery container 10 has the same configuration as that of the first embodiment except that the cross section is oval, and includes a container body 10a and a container lid 10b. Then, the current collector plate 6 on the upper end side of the power generating element 1 is connected to the back surface of the container lid 10b, and the current collector plate 7 on the lower end side is connected to the inner bottom surface of the container body 10a. It becomes a terminal, and the bottom face of the container body 10a becomes a negative electrode terminal. Further, the shaft core 2 protruding from the upper end side of the power generation element 1 is brought into contact with the back surface of the container lid 10b via a cap 8 and a spring 9 fitted in the protrusion 2a, and from the lower end side of the power generation element 1. The protruding shaft core 2 is urged by the compressed spring 9, and the lower end surface is pressed against the inner bottom surface of the container body 10a directly or via a lead piece or the like. Also in the case of the present embodiment, if the cap 8 and the spring 9 are arranged on the lower end side of the shaft core 2, the shaft core 2 is connected to the positive electrode 3, and the light weight and the heat conductivity are extremely good. Can be used.
[0024]
The non-aqueous electrolyte secondary battery having the above configuration conducts heat at the center of the power generation element 1 to the container body 10a and the container lid 10b through the shaft core 2 having excellent thermal conductivity, and quickly radiates heat to the outside. An increase in battery temperature can be suppressed. Even when subjected to vibration or impact, the shaft core 2 is sandwiched between the container body 10a and the container lid 10b of the battery container 10 by the bias of the spring 9, so that it moves or jumps inside the battery. Thus, there is no possibility of damaging the separator 5 and the like, and the shaft core 2 can be securely held.
[0025]
FIG. 5 shows a third embodiment of the present invention, and is a longitudinal sectional view showing the structure of a nonaqueous electrolyte secondary battery. In addition, the same number is attached | subjected to the structural member which has the same function as 1st Embodiment shown in FIGS. 1-2, and description is abbreviate | omitted. The nonaqueous electrolyte secondary battery of the present embodiment will be described in the case where the power generating element 1 is wound in a cylindrical shape as in the first embodiment. This nonaqueous electrolyte secondary battery uses the power generating element 1 and the shaft core 2 having the same configuration as that of the first embodiment. However, as shown in FIG. 1, only the insulating cap 8 is fitted into the upper end of the shaft core 2 disposed at the center of the power generating element 1. The power generating element 1 is housed in a battery container 10 having the same configuration as that of the first embodiment, and a current collector plate 6 on the upper end side is connected to the back surface of the container lid 10b, and a current collector plate 7 on the lower end side is provided. Since it is connected to the inner bottom surface of the container body 10a, the protrusion of the container lid 10b serves as a positive electrode terminal, and the bottom surface of the container body 10a serves as a negative electrode terminal. However, the shaft core 2 protruding from the upper end side of the power generating element 1 is brought into contact with the back surface of the protrusion of the container lid 10b via the cap 8, and the lower end surface of the shaft core 2 protruding from the lower end side of the power generating element 1 is used. Is brought into contact with the inner bottom surface of the container body 10a. In this case, the shaft core 2 into which the cap 8 is fitted is arranged with no gap between the container body 10a and the container lid 10b, or is formed so as to be slightly longer than this. It is sandwiched between them by elasticity. Further, the shaft core 2 may have its lower end surface fixed to the inner bottom surface of the container body 10a by welding or the like, and the upper end of the shaft core 2 and the cap 8 are bonded to the back surface of the container lid 10b with an adhesive. You may make it do.
[0026]
Also in the present embodiment, the shaft core 2 is in contact with the bottom surface of the container body 10a serving as the negative electrode terminal and connected to the negative electrode 4 as described above, but the cap 8 is connected to the lower end of the shaft core 2. If it is arranged on the side, it can be connected to the positive electrode 3, and aluminum or the like that is lightweight and has extremely good thermal conductivity can be used for the shaft core 2.
[0027]
The non-aqueous electrolyte secondary battery having the above configuration conducts heat at the center of the power generation element 1 to the container body 10a and the container lid 10b through the shaft core 2 having excellent thermal conductivity, and quickly radiates heat to the outside. An increase in battery temperature can be suppressed. Even when subjected to vibration or impact, the shaft core 2 is sandwiched between the container body 10a and the container lid 10b of the battery container 10, so that the separator 5 or the like is damaged by moving or jumping inside the battery. The risk of doing so is eliminated.
[0028]
In the above-described embodiment, the battery container 10 is described as having the container body 10a and the container lid 10b. However, the structure of the battery container 10 is arbitrary. In the above embodiment, the battery container 10 has been described with the positive electrode terminal and the negative electrode terminal provided on the upper surface (container lid 10b) and the bottom surface (container body 10a). The present invention can be similarly applied to a non-aqueous electrolyte secondary battery provided on the upper surface of 10. In this case, the shaft core 2 is directly sandwiched between the upper surface and the bottom surface inside the battery container 10 without using an insulating mounting member such as the cap 8, or any one of them is applied. It can also be made to contact. In addition, in this case, both end surfaces of the shaft core 2 can be fixed to the top and bottom surfaces of the battery container 10 by welding or the like.
[0029]
Furthermore, in each of the above embodiments, the case where the shaft core 2 is sandwiched has been described. However, only one of the upper and lower end surfaces of the shaft core 2 is fixed to the upper surface or the bottom surface inside the battery container 10, and the other end is free. It can also be in a state.
[0030]
Furthermore, in the above embodiment, the case where current collection is performed by welding current collector plates 6 and 7 to the upper and lower end faces of the power generation element 1 has been described. However, the current collection of the nonaqueous electrolyte secondary battery of the present invention is described. The means is not limited to this.
[0031]
Furthermore, when the rubber | gum etc. which are the elastic bodies which consist of an insulator are used instead of the spring 9 shown in the said 1st Embodiment and 2nd Embodiment, the cap 8 becomes unnecessary. Further, in the third embodiment, the upper end surface of the shaft core 2 is brought into contact with the back surface of the container lid 10b via the cap 8, but can also be fixed by adhesion or the like.
[0032]
【The invention's effect】
As is clear from the above description, according to the inventions according to claim 1 and claim 2, the heat generated in the power generation element is efficiently transmitted to the battery case through the shaft core having high thermal conductivity and is dissipated. Therefore, the battery temperature does not rise abnormally even if a large amount of heat is generated during a large current discharge. In addition, even when the battery is subjected to shock or vibration, there is no risk of the metal shaft core moving or jumping inside the battery and damaging the separator etc. Can be prevented.
[0033]
[0034]
It should be noted that by using a lightweight shaft core or battery container with extremely high thermal conductivity such as aluminum, the heat dissipation efficiency can be further increased and it can be made less susceptible to impacts and vibrations.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a structure of a non-aqueous electrolyte secondary battery according to a first embodiment of the present invention.
FIG. 2, showing a first embodiment of the present invention, is a perspective view showing a configuration of a power generation element.
FIG. 3 is a longitudinal sectional view showing a structure of a nonaqueous electrolyte secondary battery according to a second embodiment of the present invention.
FIG. 4 is a perspective view showing a configuration of a power generating element according to a second embodiment of the present invention.
FIG. 5, showing a third embodiment of the present invention, is a longitudinal sectional view showing the structure of a non-aqueous electrolyte secondary battery.
FIG. 6 is a perspective view showing a manufacturing process of a power generating element of a nonaqueous electrolyte secondary battery.
FIG. 7 shows a conventional example and is a longitudinal sectional view showing a structure of a nonaqueous electrolyte secondary battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power generation element 2 Axle core 3 Positive electrode 4 Negative electrode 5 Separator 8 Cap 9 Spring 10 Battery container

Claims (3)

In a non-aqueous electrolyte secondary battery in which a power generating element in which a strip-like positive electrode and a negative electrode are wound through a strip-shaped separator is housed in a battery container, a metal shaft core is arranged at the center of the winding of the power generating element. In addition, at least one of the upper and lower ends of the metal shaft core is fixed to the inner upper surface or the bottom surface of the battery container directly or via an attachment member, and current collecting plates are disposed on the upper and lower end surfaces of the power generation element. A non-aqueous electrolyte secondary battery characterized by the above. In a non-aqueous electrolyte secondary battery in which a power generating element in which a strip-like positive electrode and a negative electrode are wound through a strip-shaped separator is housed in a battery container, a metal shaft core is arranged at the center of the winding of the power generating element. At the same time, the upper and lower ends of the metal shaft core are abutted and sandwiched directly or via the mounting member between the inner upper surface and the bottom surface of the battery container, and current collecting plates are disposed on the upper and lower end surfaces of the power generation element. A non-aqueous electrolyte secondary battery characterized by the above. In a non-aqueous electrolyte secondary battery in which a power generating element in which a strip-like positive electrode and a negative electrode are wound in an oval shape through a strip-shaped separator is housed in a battery container, The metal shaft core is disposed, and protrusions are provided at both ends of the upper end surface of the metal shaft core, and these protrusions are formed on the inner upper surface of the battery container via the mounting member. The lower end surface of the shaft core is brought into contact with and pressed against the inner bottom surface of the battery container directly or via a lead piece, and current collecting plates are arranged on the upper and lower end surfaces of the power generation element. Water electrolyte secondary battery.

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