JP6304981B2 - Nonaqueous electrolyte secondary battery - Google Patents

Description

  Embodiments described herein relate generally to a non-aqueous electrolyte secondary battery.

  In recent years, chargeable / dischargeable rectangular parallelepiped non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are mainly used as power sources for electric vehicles such as hybrid electric vehicles and plug-in electric vehicles that are rapidly spreading. Yes. A lithium ion secondary battery has a positive electrode and a negative electrode that are wound or laminated with a separator interposed therebetween, and a nonaqueous electrolyte that is stored in a rectangular battery case (outer container) made of aluminum or an aluminum alloy. Configured.

  A positive electrode output terminal, a negative electrode output terminal, a sealing plate, a gas discharge valve, and the like are provided on the upper surface of the battery case. There is a liquid injection port under the sealing plate. After the electrolytic solution is placed in the battery case, the sealing plate is welded to close the liquid injection port.

JP 2013-020735 A

  In the manufacturing process of a lithium ion secondary battery, after pouring electrolyte solution into a battery case, a sealing plate is installed in a state where the inside of the battery case is decompressed, and welding is performed. If the time from the injection to the vacuum seal is short and the electrolyte is not completely impregnated between the electrode bodies, the electrolyte overflows from the injection port when the pressure is reduced and adheres around the injection port, resulting in poor welding. Cause.

  The present invention has been made in view of the above points, and an object thereof is to provide a non-aqueous electrolyte secondary battery capable of preventing overflow of an electrolytic solution and improving productivity.

According to the embodiment, the nonaqueous electrolytic secondary battery includes an outer container having a lid , a positive electrode plate, a negative electrode plate, and a separator, and the positive electrode plate and the negative electrode plate are wound with the separator interposed therebetween. And an electrode body housed in the exterior container together with a non-aqueous electrolyte in a state where the short side direction of the positive electrode plate and the negative electrode plate is perpendicular to the lid body, and is aligned with the lid body A pair of electrode terminals each electrically connected to the electrode body, and provided on the outside of the electrode terminal at the end in the longitudinal direction of the lid body. The liquid injection port for inject | pouring and the sealing body which seals the said liquid injection port are provided.

FIG. 1 is a perspective view illustrating an appearance of a secondary battery according to an embodiment. FIG. 2 is an exploded perspective view of the secondary battery. FIG. 3 is a plan view showing a lid of the secondary battery. FIG. 4 is a cross-sectional view showing an upper part on the lid side of the secondary battery. FIG. 5 is a plan view showing a lid of a secondary battery according to a modification.

Hereinafter, the nonaqueous electrolyte secondary battery according to the embodiment will be described in detail with reference to the drawings.
As shown in FIGS. 1 to 3, the secondary battery 10 is a non-aqueous electrolyte secondary battery such as a lithium ion battery, for example, and includes a flat, substantially rectangular parallelepiped outer container 12 and a non-aqueous electrolyte in the outer container 12. And an electrode body 2 housed together with the electrolytic solution. The outer container 12 includes a container body 1 having an open upper end and a rectangular plate-like lid body 5 that is welded to the container body and closes the opening of the container body, and the inside thereof is formed fluid-tight. The lid 5 of the outer container 12 is provided with a positive electrode terminal 6 and a negative electrode terminal 7, a safety valve 21, and a liquid injection port 17. The outer container 12 is an outer can (battery case) formed from a metal such as aluminum, an aluminum alloy, iron, or stainless steel, for example.

  The electrode body 2 is formed in a flat rectangular shape by, for example, winding a positive electrode plate and a negative electrode plate in a spiral shape with a separator interposed therebetween, and further compressing in a radial direction. The positive electrode plate is a strip-shaped current collector, a positive electrode active material layer formed on at least one surface of the current collector, and a strip-like shape extending in a short side direction from a plurality of long sides of the positive electrode current collector. And a positive electrode current collecting tab 8. The negative electrode plate has the same shape as the positive electrode plate, and is formed from a strip-shaped negative electrode current collector, a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and a plurality of locations on the long side of the current collector. It has a strip-shaped negative electrode current collecting tab 9 extending in the short side direction. The electrode body 2 wound in a spiral shape is fixed by a winding tape.

  The positive and negative electrode current collecting tabs 8 and 9 may be formed by punching a current collector, respectively. The current collector and the current collection tab are formed from, for example, a metal foil. The thickness of the metal foil, that is, the thickness per current collecting tab is desirably 5 μm or more and 50 μm or less. By setting the thickness to 5 μm or more, it is possible to prevent the current collector and the current collection tab from being broken at the time of manufacture and to achieve high current collection efficiency. Moreover, dissolution of the current collecting tab when a large current flows can be avoided. Further, by setting the thickness to 50 μm or less, it is possible to increase the number of circumferences constituting the electrode body while suppressing an increase in the thickness of the electrode body. Preferably, the thickness of the metal foil is not less than 10 μm and not more than 20 μm. Although the material of metal foil can change with the kind of active material used for a positive electrode or a negative electrode, aluminum, aluminum alloy, copper, or a copper alloy can be used, for example.

  The plurality of positive electrode current collecting tabs 8 are held together by positive electrode backup leads 14 bent in a U shape. The positive electrode backup lead 14 is also referred to as a positive electrode protection lead. Similarly, the negative electrode current collecting tab 9 is held together by the negative electrode backup lead 15 bent into a U shape.

  The electrical connection between the positive electrode backup lead 14 and the positive electrode current collector tab 8 and the electrical connection between the negative electrode backup lead 15 and the negative electrode current collector tab 9 are, for example, methods such as laser welding, ultrasonic bonding, and resistance welding. However, ultrasonic bonding is preferred. The positive and negative electrode backup leads 14 and 15 are preferably made of the same material as the positive and negative electrode current collecting tabs 8 and 9, respectively. Further, it is desirable that the thicknesses of the positive and negative electrode backup leads 14 and 15 be larger than three times the thickness of the positive and negative current collecting tabs 8 and 9.

  The positive electrode terminal 6 and the negative electrode terminal 7 are respectively provided at both ends in the longitudinal direction of the lid body 5 and project outward from the lid body 5. Specifically, rectangular recesses 19 are respectively formed at both ends in the longitudinal direction of the lid 5, and a sealing material made of an insulating material such as synthetic resin or glass, for example, a gasket 13 is formed in each of these recesses 19. Each is attached. Through holes 20 and 21 are provided at the center of each gasket 13 and recess 19.

  The positive electrode terminal 6 integrally has a stepped rectangular terminal body 6a and a connecting rod 6b extending downward from the bottom surface of the terminal body 6a. The positive electrode terminal 6 is mounted on the gasket 13 with the connecting rod 6 b inserted through the gasket 13 and the through holes 21 and 20 of the recess 19. Similarly, the negative electrode terminal 7 integrally has a stepped rectangular terminal body 7a and a connecting rod 7b extending downward from the bottom surface of the terminal body 7a. The negative electrode terminal 7 is mounted on the gasket 13 in a state where the connecting rod 7 b is inserted through the gasket 13 and the through holes 21 and 20 of the recess 19.

  As shown in FIGS. 2 and 4, the positive electrode lead 3 and the positive electrode internal insulator 53 are arranged between the positive electrode backup lead 14 and the lid 5 in the outer container 12. Between the negative electrode backup lead 15 and the lid body 5, the negative electrode lead 4 and the negative electrode internal insulator 54 are disposed.

  The positive electrode lead 3 is formed by bending a plate material at a right angle so as to have an L-shaped cross section. The positive electrode lead 3 is a current collector for electrically connecting a rectangular plate lid joint 3 a facing the lid body 5 and the positive electrode current collecting tab 8. The electric tab joint portion 3b is integrally provided. The current collecting tab joint 3 b is joined (welded) to the positive electrode backup lead 14 via a rectangular plate-like intermediate lead 16. The lid joining portion 3 a is provided with a through hole 3 e for joining the connecting rod 6 b of the electrode terminal and a through hole 3 c facing the liquid injection port 17 of the lid 5.

  The positive electrode internal insulator 53 is formed in a substantially rectangular plate shape and is larger in size than the lid bonding portion 3 a of the positive electrode lead 3. And the positive electrode internal insulator 53 is arrange | positioned in parallel with these between the cover body 5 and the cover junction part 3a, and insulates these electrically. In addition, the positive electrode internal insulator 53 is formed with a through hole 53 a for inserting the connecting rod 6 b and a through hole 53 b facing the liquid injection port 17. The connecting rod 6 b of the positive electrode terminal 6 passes through the through hole 53 a of the positive electrode internal insulator 53 and is fitted and joined to the through hole 3 e of the positive electrode lead 3. As a result, the positive terminal 6 is electrically connected to the positive current collecting tab 8 via the positive lead 3, the intermediate lead 16, and the positive backup lead 14.

  The negative electrode lead 4 is formed by bending a plate material at a right angle to form an L-shaped cross section, and is a collector for electrically connecting the negative electrode current collecting tab 9 and a rectangular plate lid joint portion 4a facing the lid body 5 in parallel. The electric tab joint portion 4b is integrally provided. The current collecting tab joint 4 b is joined (welded) to the negative electrode backup lead 15 via a rectangular plate-like intermediate lead 18. The lid joint 4a is provided with a through hole 4e for joining the connecting rod 7b of the electrode terminal.

  The negative electrode internal insulator 54 is formed in a substantially rectangular plate shape and is larger in size than the lid bonding portion 4 a of the negative electrode lead 4. And the negative electrode internal insulator 54 is arrange | positioned in parallel with these between the cover body 5 and the cover junction part 4a, and insulates these electrically. The negative electrode inner insulator 54 is formed with a through hole 54a for inserting the connecting rod 7b. The connecting rod 7 b of the negative electrode terminal 7 passes through the through hole 54 a of the negative electrode internal insulator 54 and is fitted and joined to the through hole 4 e of the negative electrode lead 4. Thus, the negative electrode terminal 7 is electrically connected to the negative electrode current collecting tab 9 via the negative electrode lead 4, the intermediate lead 18, and the negative electrode backup lead 15.

  As shown in FIG. 1 to FIG. 4, a safety valve (pressure release valve) 21 that functions as a gas exhaust mechanism and a nonaqueous electrolyte injection port 17 are formed in the lid 5 of the outer container 12. The safety valve 21 is provided between the positive electrode terminal 6 and the negative electrode terminal 7 at the center in the longitudinal direction of the lid body 5. The safety valve 21 is formed to have a plate thickness that is about half that of the lid 5. When gas is generated in the outer container 12 due to an abnormal mode or the like of the secondary battery 10 and the internal pressure in the outer container rises to a predetermined value or more, the safety valve 21 is opened, the inner pressure is lowered, the outer container 12 is ruptured, etc. To prevent malfunctions.

  The nonaqueous electrolyte injection port 17 is formed at one end of the lid 5 in the longitudinal direction. In the present embodiment, the liquid injection port 17 is provided outside the positive electrode terminal 6 and between the positive electrode terminal and one end in the longitudinal direction of the lid 5. That is, the liquid injection port 17 is provided on the side opposite to the safety valve 21 with respect to the positive electrode terminal 6, and is sufficiently separated from the safety valve 21. The liquid injection port 17 is located opposite to and aligned with the through hole 53b of the positive electrode internal insulator 53 and the through hole 3c of the lid bonding portion 3a. In addition, after injecting the non-aqueous electrolyte into the outer container 12 through the injection port 17, the injection port 17 is sealed with, for example, a disk-shaped sealing lid 22.

  In the non-aqueous electrolyte secondary battery 10 configured as described above, the electrode body 2, the positive and negative electrode backup leads, the positive and negative electrode leads, and the positive and negative electrode internal insulators are accommodated in the outer container 12 at the time of manufacture. After injecting the non-aqueous electrolyte from the liquid port 17, the inside of the outer container is decompressed, and the liquid injection port 17 is sealed with the sealing lid 22 in this decompressed state. In the conventional secondary battery, at the time of decompression, a part of the non-aqueous electrolyte adhering to the inner surface of the lid 5 may overflow from the liquid injection port and leak to the outside. On the other hand, in the secondary battery 10 according to the present embodiment, the liquid injection port 17 is provided at the end in the longitudinal direction of the lid 5, that is, outside the electrode terminal. Among the non-aqueous electrolytes adhering to the non-aqueous electrolyte, the non-aqueous electrolyte present in the vicinity of the injection port 17 is greatly reduced. Therefore, the possibility that the non-aqueous electrolyte leaks out from the liquid injection port 17 during the decompression operation of the outer container 12 can be greatly reduced. Therefore, it is possible to eliminate the adverse effect (for example, occurrence of poor welding) on the electrode terminals and the like due to the leaked electrolyte, and to improve the productivity and reliability of the secondary battery.

  The liquid injection port 17 is provided on the opposite side of the safety valve with respect to the electrode terminal, and is provided sufficiently away from the safety valve 21. Therefore, compared with the case where the liquid injection port 17 is provided in the vicinity of the safety valve in the lid body, the mechanical strength of the lid body and the safety valve 21 can be maintained, and inadvertent opening of the safety valve is prevented. It is possible to improve the performance.

Furthermore, through holes 53 b and 3 c facing the liquid injection port 17 are provided in each of the positive electrode internal insulator 53 and the positive electrode lead 3 positioned to face the inner surface of the lid 5. Therefore, the nonaqueous electrolytic solution injected from the liquid injection port 17 can be smoothly injected into the outer container 12 through the through holes 53b and 3c. In the positive electrode internal insulator 53 and the positive electrode lead 3, a portion facing the liquid injection port 17 may be cut out instead of providing a through hole.
From the above, according to the present embodiment, a non-aqueous electrolyte secondary battery in which the problem of overflow of the electrolytic solution is solved and productivity is improved can be obtained.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
As in the modification shown in FIG. 5, the liquid injection port 17 may be provided at the corner of the lid at one end in the longitudinal direction of the lid 5. The liquid injection port 17 may be provided not only on the outside of the positive electrode terminal 6 but also on the opposite end of the longitudinal direction of the lid, that is, on the outside of the negative electrode terminal 7.
The matters described in the claims at the beginning of the filing of the present application will be added.
(Additional item 1)
An exterior container having a lid,
An electrode body housed in the outer container together with a non-aqueous electrolyte,
A pair of electrode terminals provided side by side on the lid, each electrically connected to the electrode body;
A liquid injection port for injecting a non-aqueous electrolyte into the outer container provided on the outer side of the electrode terminal at the longitudinal end of the lid;
A sealing body for sealing the liquid injection port;
A non-aqueous electrolyte secondary battery.
(Appendix 2)
The said cover body has a safety valve provided between the pair of electrode terminals, and the liquid injection port is provided on the opposite side of the safety valve with respect to one electrode terminal. Non-aqueous electrolyte secondary battery.
(Additional Item 3)
A plate-like internal insulator provided opposite to the inner surface of the lid in the outer container, and provided between the internal insulator and the electrode body, and electrically connected to the electrode body. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein each of the internal insulator and the lead has a through hole facing the liquid injection port.
(Appendix 4)
The nonaqueous electrolyte according to any one of additional items 1 to 3, wherein the lid is formed in an elongated rectangular shape, and the liquid injection port is provided at one end and a corner in the longitudinal direction of the lid. Secondary battery.

DESCRIPTION OF SYMBOLS 1 ... Container main body, 5 ... Cover body, 6 ... Positive electrode terminal, 7 ... Negative electrode terminal, 10 ... Nonaqueous electrolyte secondary battery,
DESCRIPTION OF SYMBOLS 12 ... Outer container, 13 ... Gasket, 17 ... Injection hole, 21 ... Safety valve, 22 ... Sealing lid

Claims (6)

An exterior container having a lid,
A positive electrode plate, a negative electrode plate, and a separator, the positive electrode plate and the negative electrode plate being wound with the separator interposed therebetween, and a short-side direction of the positive electrode plate and the negative electrode plate with respect to the lid An electrode body housed in the outer container together with a non-aqueous electrolyte in a vertical state ;
A pair of electrode terminals provided side by side on the lid, each electrically connected to the electrode body;
A liquid injection port for injecting a non-aqueous electrolyte into the outer container provided on the outer side of the electrode terminal at the longitudinal end of the lid;
A sealing body for sealing the liquid injection port;
A non-aqueous electrolyte secondary battery. The said cover body has a safety valve provided between the said pair of electrode terminals, The said liquid injection port is provided in the other side of the said safety valve with respect to one electrode terminal. Non-aqueous electrolyte secondary battery. The electrode body includes a positive electrode current collecting tab extending from the long side of the positive electrode plate toward the lid body in the short side direction, and the long electrode side of the negative electrode plate toward the lid body in the short side direction. An extended negative electrode current collecting tab,
The non-aqueous electrolyte secondary battery includes a positive electrode lead electrically connecting the positive electrode current collecting tab and one of the pair of electrode terminals, and a negative electrode current collecting tab and the other of the pair of electrode terminals. A negative electrode lead for electrically connecting the two,
The nonaqueous electrolyte secondary battery according to claim 1 or 2.   A plate-like internal insulator provided opposite to the inner surface of the lid in the outer container, and provided between the internal insulator and the electrode body, and electrically connected to the electrode body. The non-aqueous electrolyte secondary battery according to claim 1, wherein each of the internal insulator and the lead has a through hole facing the liquid injection port. The nonaqueous electrolyte secondary battery according to claim 4, wherein the nonaqueous electrolyte injected from the liquid injection port passes through the through hole of the lead after passing through the through hole of the internal insulator. The nonaqueous electrolyte according to any one of claims 1 to 5 , wherein the lid is formed in an elongated rectangular shape, and the liquid injection port is provided at one end and a corner of the lid in the longitudinal direction. Secondary battery.