JPH0658554U - Thin non-aqueous electrolyte battery - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a thin non-aqueous electrolyte battery having improved reliability and excellent load characteristics by preventing an internal short circuit by improving a current collecting lead. [Structure] A positive electrode and a negative electrode having a rectangular sheet shape are wound with a separator interposed between the positive electrode and the negative electrode, and a current collector for both the positive electrode and the negative electrode taken out from the center of winding of the electrode plate group. The lead for the L shape and L
It is characterized in that the bent portion is bent so as to form a surface parallel to the end surface of the electrode plate group.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thin non-aqueous electrolyte battery that is required to have high load characteristics, and more particularly to a method of configuring a current collecting lead of an electrode plate.

[0002]

[Prior art]

 In recent years, along with the remarkable portability and intelligence of cordless information and communication devices such as mobile phones and camcorders, small and lightweight batteries with high energy density have been demanded as the power source for driving them. Electrolyte batteries, especially lithium secondary batteries, are highly anticipated as the mainstay of next-generation batteries, and their potential market size is also very large. As for the shape, the effective use of space is being emphasized as the equipment becomes thinner.

As a thin sealed battery, nickel-cadmium storage batteries and lead storage batteries, and recently nickel-hydrogen storage batteries have been developed and put into practical use. In these battery systems, a high-concentration aqueous solution of alkali or acid is used as the electrolytic solution, and the electrode plate group is composed of strip-shaped electrode plates that are stacked alternately with positive and negative electrodes through a separator. The negative and negative electrode current collecting leads are attached to each electrode plate and have a rectangular shape.

[0004]

[Problems to be solved by the device]

 However, since the conductivity of the electrolyte is low in a battery using a non-aqueous electrolyte whose main component is an organic electrolyte such as a lithium battery, an electrode plate having the same thickness as the above battery system is used. If the electrode plate group is constructed, sufficient high load characteristics cannot be obtained. Further, in the case of a secondary battery, not only in a system using metallic lithium for the negative electrode, but also in a battery system using a compound that electrochemically intercalates / deintercalates lithium, lithium batteries can be charged during high-current charging. It is said that there is a problem with safety, such as the fact that it deposits, and the form of deposition is mainly needle-like, which falls off from the negative electrode or penetrates the separator and contacts the positive electrode, causing internal short circuits and ignition. ing.

In order to solve these problems, it is conceivable to reduce the number of plates to increase the number of plates and to increase the effective reaction area to reduce the current density, but it is difficult to handle a large number of thin plates because it is difficult to handle them. Very difficult to configure.

Therefore, a method of forming an electrode plate group by winding a rectangular sheet-shaped positive electrode and negative electrode with a separator interposed therebetween is conceivable. When the electrode plate group is constructed by this method, it is possible to take out both the positive electrode and negative electrode current collecting leads from the winding center portion of the electrode plate group in the same direction and in the opposite direction. In non-aqueous electrolyte batteries, it is difficult to secure the electrical connection of the leads due to contact, so it is common to make electrical connection by spot welding or the like. In the case of taking it out in the opposite direction, it is conceivable to spot weld one of the current collecting leads to the bottom of the electrode plate group by using the space in the center of the electrode group, as in the case of the spiral cylindrical battery. However, in the case of the thin battery having the above electrode plate group, it is extremely difficult to secure a space for spot welding the current collecting lead to the bottom portion in the central portion of the electrode plate group. Therefore, it is necessary to use the method of taking out in the same direction. When taking out in the same direction, if you take out the rectangular current collecting lead perpendicularly to the electrode plate group as in the past, the bent shape of the lead when inserting the electrode plate group into the battery case and sealing it Is difficult to keep constant, and the current collecting leads of the positive electrode or the negative electrode or the current collecting leads of the positive electrode or the negative electrode and the electrode plate group easily come into contact with each other, which causes an internal short circuit. Further, in order to prevent an internal short circuit, the insulation process of the positive electrode or negative electrode current collecting lead becomes complicated.

The present invention solves the problems associated with the conventional method of forming the current collecting lead, and an object of the present invention is to provide a thin non-aqueous electrolyte battery excellent in high load characteristics.

[0008]

[Means for Solving the Problems]

 In order to achieve this object, the thin non-aqueous electrolyte battery of the present invention has an electrode plate group formed by winding a rectangular sheet-shaped positive electrode and negative electrode through a separator. Both the positive electrode and negative electrode current collecting leads taken out from the center of the winding are formed in an L shape, and at the bent portion of the L shape, a surface parallel to the end surface of the electrode plate group is formed. It is characterized by being bent into.

[0009]

[Action]

 By such a method of constructing the positive electrode and negative electrode current collecting leads, the bent shape of the current collecting leads inside the battery can be kept constant, and the current collecting lead between the positive electrode and the negative electrode or between the positive electrode and the negative electrode can be collected. This is a thin non-aqueous electrolyte battery that has excellent high load characteristics and does not cause defects such as internal short circuits by making it difficult to contact the battery leads with the electrode plate group and reducing internal short circuits. Is provided.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. A vertical sectional view of the thin lithium secondary battery of the present invention is shown in Fig. 1 (a), a horizontal sectional view is shown in Fig. 1 (b), a structural view is shown in Fig. 2, and a component diagram is shown in Fig. 3. 1, 2 and 3, 1 is an L-shaped positive electrode current collecting lead, 2 is an L-shaped negative electrode current collecting lead, 3 is a positive electrode plate, 4 is a negative electrode plate, 5 is a separator, and 6 is A battery case, 7 is a sealing plate, and 8 is an electrode plate group.

The L-shaped positive electrode current collecting lead 1 is formed by forming an aluminum plate having a width of 2 mm and a thickness of 0.15 mm with a long side of 41 mm and a short side of 15 mm.

The L-shaped negative electrode current collecting lead 2 is formed by forming a nickel plate having a width of 2 mm and a thickness of 0.10 mm with a long side of 42 mm and a short side of 15 mm.

The positive electrode plate 3 is made of lithium carbonate (LiCO₃) And tricobalt tetroxide (Co₃O_Four) Are mixed and fired in air at 900 ° C., lithium cobalt oxide (LiCoO 2 ₂ ) As an active material, 3% by weight of acetylene black as a conductive agent is mixed therein, and then 7% by weight of an aqueous dispersion of polytetrafluoroethylene resin is kneaded as a binder to prepare a paste-like mixture. A core material made of aluminum foil is applied on both sides, dried and rolled. Further, a part of the mixture is peeled off on both sides by 3 mm in width, and the L-shaped positive electrode current collecting lead 1 is spot-welded. The dimensions of the positive electrode plate 3 are a width of 34 mm, a length of 95 mm, and a thickness of 0.170 mm.

The negative electrode plate 4 is made by spheroidal graphite obtained by heat-treating mesophase pitch at 2800 ° C. in an argon atmosphere as an active material, and kneading 5% by weight of an aqueous dispersion of polytetrafluoroethylene resin as a binder. The paste-form mixture was applied on both sides of a core material made of copper foil, dried and rolled. Further, both sides of the end are separated by a width of 3 mm, and the L-shaped negative electrode current collecting lead 2 is spot-welded. The dimensions of the negative electrode plate 4 are 36 mm in width, 132 mm in length, and 0.205 mm in thickness.

Here, as a result of preliminary examination of various carbon materials having different physical properties and structures, a carbon material having a lattice spacing (d ₀₀₂ ) by powder X-ray diffraction method of 0.342 nm or less has a high capacity, It was also found to be excellent in reversibility. By the way, the spheroidal graphite obtained by heat-treating mesophase pitch at 2800 ° C. in an argon atmosphere has a lattice spacing (d ₀₀₂ ) of 0.342 nm or less by a powder X-ray diffraction method.

As the separator 5, a porous film made of polypropylene was used after being cut wider than the positive electrode 3 and the negative electrode 4.

These positive and negative electrode plates 3 and 4 were wound around a separator 5 and the end of the separator 5 was fixed with an adhesive tape made of polypropylene to form an electrode plate group 8 having an oval cross section.

Next, although not shown, after inserting the lower insulating plate into the battery case 6, the electrode plate group 8 was accommodated and the upper insulating ring was further inserted. After grooving the upper part of the battery case 6, the L-shaped positive electrode current collecting lead 1 and the L-shaped negative electrode current collecting lead 2 are bent to form an electrode plate group 8 as shown in FIGS. 1 and 2. A parallel surface is formed, and the short side of the L-shaped positive electrode current collecting lead 1 is on the terminal provided on the sealing plate 7, and the L-shaped negative electrode current collecting lead 2 is on the back surface of the sealing plate 7. Each was connected by spot welding and a non-aqueous electrolyte was injected. The non-aqueous electrolyte is a mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) in a volume ratio of 1: 1 and lithium hexafluorophosphate (LiPF ₆ ) dissolved at 1 mol / l. I was there. After that, it was sealed and a battery was constructed. The battery has dimensions of 6 mm in thickness, 17 mm in width and 48 mm in height.

Battery assembly of the thin sealed lithium secondary battery configured as described above was performed. The occurrence of voltage defects due to internal short circuit during battery assembly and after charge / discharge was evaluated. The charging / discharging conditions were such that charging was 0.2 CmA and discharging was 0.2 CmA for 10 cycles of charging / discharging.

As a comparative example, a rectangular positive electrode current collecting lead 11 and a rectangular negative electrode current collecting lead 12 are used, and both current collecting leads 11 and 12 are connected to the electrode plate group 8. Except for connecting the rectangular positive electrode current collecting lead 11 to the terminal provided on the sealing plate 7 and the rectangular negative electrode current collecting lead 12 to the back surface of the sealing plate 7 by spot welding, respectively. Was evaluated by simultaneously constructing batteries having exactly the same configuration as in the above example. The rectangular positive electrode current collecting lead 11 of the comparative example is an aluminum plate having a width of 2.0 mm, a length of 50 mm and a thickness of 0.15 mm. The rectangular negative electrode current collecting lead 12 is a nickel plate having a width of 2.0 mm, a length of 50 mm and a thickness of 0.10 mm. A vertical sectional view of the comparative example is shown in FIG. 4A, a horizontal sectional view is shown in FIG. 4B, a structural diagram is shown in FIG. 5, and a component diagram is shown in FIG.

The evaluation results show that when the rectangular positive electrode current collecting lead 11 and the rectangular negative electrode current collecting lead 12 of the comparative example are used, an internal short circuit is caused by the current collecting lead. The voltage failure caused by about 10% at the time of assembling the battery and about 20% after the above charging / discharging conditions, whereas the L-shaped positive electrode current collecting lead 1 and the L-shaped negative electrode collecting electrode of the present invention. When the electrical lead 2 was used, no internal short circuit occurred. When both the L-shaped positive electrode current collecting lead 1 and the L-shaped negative electrode current collecting lead 2 are taken out in the same direction from the winding center of the electrode plate group 8, the positive electrode and the negative electrode current collecting As shown in Fig. 1, Fig. 2 and Fig. 3, both leads are L-shaped and bent in the middle to form a surface that is parallel to the electrode plate group 8. Can be maintained in a constant shape, and it becomes difficult for the positive electrode and negative electrode current collecting leads to come into contact with each other, or between the positive electrode or negative electrode current collecting leads and the electrode plate group, making it possible to reduce internal short circuits.

In addition, by using the L-shaped positive electrode current collecting lead 1 and the L-shaped negative electrode current collecting lead 2, the process of insulating the positive electrode and the negative electrode current collecting lead can be performed in the manufacturing process. It can be simplified, leading to a reduction in processes.

In addition, although the lithium secondary battery using intercalation / deintercalation of lithium ion is described in the embodiment, the ion of other alkali metal such as sodium and calcium, or alkaline earth metal ion is used. It is also effective for the non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery having a negative electrode of an alkali metal such as lithium, sodium and calcium, or an alkaline earth metal, and a primary battery.

[0024]

[Effect of device]

 As described above, the present invention relates to a thin non-aqueous electrolyte battery having an electrode plate group formed by winding a rectangular sheet-shaped positive electrode and negative electrode with a separator interposed between them. By forming both the positive electrode and the negative electrode current-collecting leads that are taken out in an L-shape and bending the L-shaped bent portion so as to form a surface parallel to the end surface of the electrode plate group. It is possible to improve reliability by reducing internal short circuits and reduce manufacturing costs by simplifying the manufacturing process.

[Brief description of drawings]

1A is a vertical cross-sectional view of a thin non-aqueous electrolyte battery according to an embodiment of the present invention, and FIG. 1B is a horizontal cross-sectional view of a thin non-aqueous electrolyte battery according to an embodiment of the present invention.

FIG. 2 is a structural diagram of a thin non-aqueous electrolyte battery according to an embodiment of the present invention.

FIG. 3A is a part view of a positive electrode of a thin non-aqueous electrolyte battery according to an embodiment of the present invention. FIG. 3B is a part view of a negative electrode of a thin non-aqueous electrolyte battery according to an embodiment of the present invention.

4A is a vertical cross-sectional view of a thin non-aqueous electrolyte battery of a comparative example. FIG. 4B is a horizontal cross-sectional view of a thin non-aqueous electrolyte battery of a comparative example.

FIG. 5 is a structural diagram of a thin non-aqueous electrolyte battery of a comparative example.

FIG. 6A is a part diagram of a positive electrode of a thin non-aqueous electrolyte battery of a comparative example. FIG. 6B is a part diagram of a negative electrode of a thin non-aqueous electrolyte battery of a comparative example.

[Explanation of symbols]

 1 L-shaped positive electrode current collecting lead 2 L-shaped negative electrode current collecting lead 3 Positive electrode plate 4 Negative electrode plate 5 Separator 6 Battery case 7 Sealing plate 8 Electrode plate group 11 Rectangular positive electrode current collecting lead 12 Rectangle Negative electrode current collecting lead

Claims (1)

[Scope of utility model registration request] 1. An electrode plate group constituted by winding a rectangular sheet-shaped positive electrode and a negative electrode with a separator interposed therebetween, wherein both the positive electrode and the negative electrode taken out from the winding center of the electrode plate group. A thin non-aqueous electrolyte battery, characterized in that the current collecting lead is formed in an L-shape and is bent so as to form a surface parallel to the end surface of the electrode plate group in the L-shaped bent portion.