JPH04249072A - Secondary batteries and assembly battery using them - Google Patents

Abstract

PURPOSE:To provide an assembly battery of simple constitution and secondary batteries which can constitute such an assembly battery. CONSTITUTION:An assembly battery 50 uses a cylindrical secondary battery 41 with non-aqueous electrolyte, in which the battery can 5 forms a positive electrode part 41a and the battery lid 7 forms a negative electrode terminal 41b. This No.1 battery 41 and a No.2 battery 42, in which battery can 5' forms a negative electrode part 42b and battery lid 7 forms a positive electrode terminal 42a, are consolidated by wrapping a metal foil 45. Thus an assembly battery 50 is accomplished, wherein time negative electrode terminal 41b of the No.1 battery 41 becomes neg. electrode side and the positive terminal 42a of the No.2 battery 42 becomes pos. electrode side. The inner surfaces of the battery can 5 of No.1 battery 41 are lined with Al material to provide electrochemical stability.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery and a battery assembly using the secondary battery.

0002

[Background Art] In recent years, electronic devices such as video cameras and headphone stereos have improved in performance and become smaller in size, and there is a demand for higher energy density in the secondary batteries that power these electronic devices. has been done.

In order to meet these demands, a non-aqueous electrolyte secondary battery having a negative electrode made of a material that can be doped and dedoped with lithium, such as lithium metal, lithium alloy, or carbonaceous material, has been developed. It is being actively carried out. In such a non-aqueous electrolyte secondary battery, the negative electrode is usually connected to the battery can, and a high battery voltage of 3.5 V or more can be obtained per single cell.

By the way, in general, secondary batteries are rarely used as single cells in electronic equipment, and by using assembled batteries made by combining multiple batteries, voltage and capacity can be obtained according to the electronic equipment used. ing.

[0005]

When constructing a battery pack as described above, the batteries are connected by, for example, welding a lead plate to each electrode of the batteries. Therefore, in a battery pack having a large number of cells, a considerable amount of effort is required in the assembly process, and the workability and productivity of assembling the battery pack are poor.

[0006] Furthermore, in the assembled battery, there is a problem in that the insulating tube covering the single cell is torn by the above-mentioned lead plate, causing an external short circuit.

In order to solve the above-mentioned problems, the present inventors obtained two types of batteries in which each battery can is connected to a positive electrode and a negative electrode, respectively. We came up with the idea that a series-connected assembled battery could be obtained simply by bringing the cans into contact with each other and combining them without using lead plates.

[0008] An object of the present invention is to provide an assembled battery with a simple structure and a secondary battery that can constitute this assembled battery.

[0009]

[Means for Solving the Problems] The present invention has been made based on the above-mentioned ideas of the present inventors, and the invention of claim 1 provides an electrode body comprising a negative electrode and a positive electrode; A secondary battery including a battery case housing an electrode body and to which the positive electrode is electrically connected, and an electrode terminal portion provided at one end of the battery case and to which the negative electrode is electrically connected. It's a battery.

[0010] The invention of claim 2 also provides that in the secondary battery, the negative electrode and the positive electrode in the electrode body are each configured to be doped with lithium and dedoped, and a non-aqueous electrolyte is provided in the battery case. This is a secondary battery that contains liquid and the inner surface of the battery case is covered with an aluminum material.

[0011] Furthermore, the invention as claimed in claim 3 provides the first secondary battery as claimed in claim 1, and the negative electrode in the electrode body as claimed in claim 1 being electrically connected to the battery case, and that the positive electrode as described above is electrically connected to the battery case. This is an assembled battery formed by combining a second secondary battery configured by being electrically connected to the electrode terminal portion.

[0012] Furthermore, the invention according to claim 4 is a battery containing the first secondary battery according to claim 2, the electrode body according to claim 2, and the negative electrode which is electrically connected to the first secondary battery according to claim 2. A second battery case comprising a battery case and an electrode terminal portion provided on one end side of the battery case and to which the positive electrode is electrically connected, the second battery case containing a non-aqueous electrolyte. This is an assembled battery consisting of a secondary battery and a secondary battery.

[0013]

[Operation] The secondary battery of claim 1 is used as a first secondary battery, and this first secondary battery and a second secondary battery whose negative electrode of the electrode body is connected to the battery can are connected to each other in a battery can. Since they can be brought into contact with each other, a battery assembly of a pair of secondary batteries connected in series can be easily obtained without connecting lead plates or the like.

Furthermore, when the secondary battery is a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte, the inner surface of the battery case to which the positive electrode is connected is covered with an aluminum material. It is preferable because electrochemical stability is increased.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic vertical cross-sectional view of a non-aqueous electrolyte secondary battery in which the battery case 5 is the positive electrode side and the battery lid 7 is the negative electrode side.

[0016] The negative electrode 1 is formed into a band shape, with a negative electrode material mainly made of a carbonaceous material as a negative electrode active material carrier that can be doped with lithium and dedoped, provided on both sides of a band-shaped negative electrode current collector 9. . From this negative electrode 1, negative electrode lead 1
1 has been derived.

The positive electrode 2 is constructed in the form of a band, with positive electrode material mainly consisting of LiCoO2 as a positive electrode active material capable of doping and dedoping lithium, provided on both sides of a positive electrode current collector 10 in the form of a band.

The above-described band-shaped negative electrode 1 and positive electrode 2 are laminated with a pair of separators 3a and 3b made of microporous polypropylene film interposed therebetween, and then wound by spirally winding a large number of turns. An electrode body 15 is configured. Note that 33 is a winding core.

The battery case 5 is made of a cladding material consisting of a stainless steel layer 16 and an aluminum layer 17. An aluminum layer 17 is located on the inner surface side of the battery case 5. This provides electrochemical stability against non-aqueous electrolytes, and the stainless steel layer 16 is placed on the outer surface to provide sufficient strength. Note that the stainless steel layer 16
The outer surface is nickel plated. Also,
The stainless steel layer 16 may be made of steel or the like.

A wound electrode body 15 is housed in the battery case 5 as described above, and lithium hexafluorophosphate (LiPF6) as an electrolyte is mixed with propylene carbonate and 1,
A nonaqueous electrolyte obtained by dissolving an equal amount of 2-dimethoxyethane in a nonaqueous solvent mixed at a ratio of 1 mol/liter is injected.

The negative electrode lead 11 led out from the negative electrode 1 of the wound electrode body 15 is welded to the protrusion 34a of the safety valve 34, and the positive electrode lead 12 led out from the positive electrode 2 is welded to the bottom surface of the battery can 5. has been done. Note that the wound electrode body 15
Circular insulating plates 5a and 5b are respectively arranged on the upper and lower end surfaces of.

The metal safety valve 34 and the stripper 36 are integrally provided in the intermediate fitting body 35. The safety valve 34 and the metal battery lid 7 are closely attached at their outer peripheries, and are provided at the upper end of the battery case 5 with an insulating sealing gasket 6 interposed therebetween. By caulking the upper end of the battery case 5, the battery lid 7 serving as the negative electrode terminal portion and the battery case 5 serving as the positive electrode side are electrically insulated, and the battery case 5 is hermetically sealed. Note that the lower end of the insulation sealing gasket 6 is in contact with the insulation plate 4a, and the lower end of the insulation sealing gasket 6 is in contact with the insulation plate 4a and the first wound electrode.
It is in close contact with the upper end surface of 5.

Furthermore, when the internal pressure of the sealed battery increases for some reason, the safety valve 34 opens the protrusion 3 upward in FIG.
4a as the center, and the negative electrode lead 11 and the protrusion 34
The configuration is such that the connection with a is cut off. Furthermore, the safety valve 34 is provided with a cleavage portion (not shown) that ruptures when the internal pressure of the battery increases and the safety valve 34 is deformed, and the battery cover 7 is provided with a hole (not shown). As described above, the battery of this embodiment is equipped with a dual safety device including a current interrupt device and an internal pressure release device.

The non-aqueous electrolyte secondary battery as described above can be constructed into a cylindrical shape with a diameter of 15 mm and a height of 50 mm, for example. Note that this battery can be used after being charged with an upper limit voltage of 4.1V.

Various materials that can be doped and dedoped with lithium can be used for the negative electrode 1 in the non-aqueous electrolyte secondary battery as described above. For example, lithium metal,
Lithium alloys, conductive polymers such as polyacetylene, carbonaceous materials such as coke, or carbon materials can be used.

Further, as the positive electrode active material, a material that can be doped with lithium and dedoped is used, and it is preferable to use a material that contains a sufficient amount of lithium. For example, lithium-cobalt composite oxides such as LiCoO2, lithium-nickel composite oxides, and lithium-cobalt-nickel composite oxides such as LiMnO4, which are represented by the general formula LixMO2 (M is at least one of Co and Ni), are preferable. It may also be a lithium-manganese composite oxide, a vanadium oxide such as V2O5, or the like.

[0027] As the non-aqueous electrolyte, for example, a lithium salt electrolyte dissolved in an organic solvent (non-aqueous solvent) can be used.

The organic solvent here is not particularly limited, but includes, for example, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-
Diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-diexolane, 4-methyl-1,3-
Dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, etc. can be used alone or in combination of two or more. Any conventionally known electrolyte can be used, and Li
ClO4, LiAsF6, LiPF6, LiBF
4, LiB(C6H5)4, LiCl, LiB
r, CH3 SO3 Li, CF3 SO3 Li, etc.

Experimental Example A non-aqueous electrolyte secondary battery shown in FIG. 1 and, for comparison, a nickel-plated iron battery case (with an aluminum layer on the inner surface) as the battery case 5 in FIG. A non-aqueous electrolyte secondary battery similar to that shown in FIG. 1 was manufactured, except that a non-aqueous electrolyte was used.

The two types of batteries mentioned above were charged at a constant current of 100 mA for 8 hours with the upper limit voltage set at 4.1V. Thereafter, a cycle life test was conducted in which one cycle consisted of discharging at a constant current of 80 mA to a final voltage of 2.75 V and then charging at a constant current of 400 mA to an upper limit voltage of 4.1 V. Then, the discharge capacity was measured for each cycle.

FIG. 2 shows how the discharge capacity changes with cycles in the above-mentioned cycle life test. As is clear from FIG. 2, the battery of this example had no problems even after 100 cycles, but the battery of the comparative example reached the end of its life at the 20th cycle. When the battery of this comparative example was disassembled and observed, the iron battery case corroded.
It was observed that precipitates penetrated the separator of the wound electrode body. It is presumed that this precipitate was caused by iron and nickel ions eluted from the battery case and deposited in the separator. It is thought that this precipitate penetrated the separator, causing an internal short circuit and shortening the life of the battery.

As explained above, in a non-aqueous electrolyte secondary battery having a discharge voltage of 3.5 V or more and using the battery case 5 side as the positive electrode, an aluminum layer 1 is formed on the inner surface of the battery case 5.
By providing 7, electrochemical stability can be achieved with respect to non-aqueous electrolytes, and capacity deterioration due to charge/discharge cycles can be prevented. It is preferable to use an aluminum-stainless steel cladding material (laminated plate) to make the above-mentioned battery case 5, and such a cladding material can also provide strength as a battery body.

Next, two examples of assembled batteries are shown in FIGS. 3(A) and 4(B). In the assembled battery 50 shown in FIG.
The non-aqueous electrolyte secondary battery shown in FIG. 1 is referred to as a first battery 41. A non-aqueous electrolyte secondary battery that is substantially the same as the battery shown in FIG. is the second battery 42. Note that the battery case in this second battery 42 may be made of stainless steel or steel instead of the cladding material as shown in FIG.

In the first battery 41, the battery case 5 is the positive electrode portion 41a, and the battery lid 7 is the negative electrode terminal portion 41b. In the second battery 42, the battery case 5' is connected to the negative electrode part 42.
b, and the battery lid 7 is the positive electrode terminal portion 42a.

As shown in FIGS. 3(A) and 3(B), the assembled battery 5
In the case 0, the battery case 5 of the first battery 41 and the battery case 5' of the second battery 42 are brought into contact with each other and integrated by being wrapped with metal foil 45. As a result, the positive electrode side 41a of the first battery 41 and the second battery 42
is electrically connected to the negative electrode portion 42b. In this case, as shown in FIG. 3(B), the electrical connection between the battery cans 5 of the first battery 41 and the battery cans 5' of the second battery 42 is made by extending the battery cans 5, 5' widely. This is ensured by the covering metal foil 45. As described above, the assembled battery 50 is constructed in which the positive electrode terminal portion 42a is the positive electrode side and the negative electrode terminal portion 41b is the negative electrode side.

According to the assembled battery 50 using a non-aqueous electrolyte secondary battery as shown in FIG. 1, the battery voltage between the negative electrode terminal portion 41b and the positive electrode terminal portion 42a is 8.2V. Further, in order to eliminate external short circuits, it is preferable to further cover the outer surface of the metal foil 45 with an insulating sheet material or the like. Alternatively, the outer surface of the metal foil 45 may be treated to obtain insulation properties.

FIG. 4 is an example of another assembled battery, and in this assembled battery 51, the negative terminal portion 41b of the first battery 41
and the positive electrode terminal portion 42a of the second battery 42 are configured to face in opposite directions. Other than this, the assembled battery is 50
It has the same configuration as .

According to the battery packs 50 and 51 described above,
A pair of non-aqueous electrolyte secondary batteries 41 and 42 are simply connected to a metal foil 45.
By winding the wire around the wire, a series-connected battery pack can be easily obtained. As a result, the work of connecting lead plates for each electrode, which was conventionally necessary in the manufacturing process of assembled batteries, becomes unnecessary, and it is possible to reduce the number of man-hours and improve productivity. Furthermore, the sheathing tube for insulation by the lead plate is not torn, and external short circuits can be prevented.

Although the secondary battery in this example was a cylindrical non-aqueous electrolyte secondary battery, the present invention can also be applied to other secondary batteries, such as a prismatic type. It's okay.

[0040]

According to the secondary battery according to the invention of claim 1, a battery whose battery case is on the positive electrode side and another battery whose battery case is on the negative electrode side are brought into contact with each other. Therefore, the assembled battery according to claim 3 can be easily constructed. According to the assembled battery of claim 3, since the lead plates for connecting each electrode and the work of connecting the lead plates are not required, it is possible to achieve cost reduction, reduction in man-hours, and improvement in productivity in the manufacturing process of the assembled battery. . Furthermore, the problem of external short circuits caused by lead plates is eliminated.

Further, according to the invention of claim 2, when the secondary battery is a non-aqueous electrolyte secondary battery, since the inner surface of the battery case is covered with an aluminum material, the battery case is connected to the positive electrode side. This can prevent electrochemical corrosion on the inner surface of the battery case. According to the assembled battery of claim 4, since a non-aqueous electrolyte secondary battery having a high battery voltage can be combined, an assembled battery with a high battery voltage and a high capacity can be produced with cost reduction, man-hour reduction, and productivity. You can gain while achieving improvements.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a non-aqueous electrolyte secondary battery according to an embodiment of the present invention.

FIG. 2 is a diagram showing how the battery discharge capacity changes with cycles, which was obtained by conducting a cycle life test on the secondary battery of the example shown in FIG. 1 and the secondary battery of the comparative example.

FIG. 3 is a front view of an example battery assembly consisting of the secondary battery shown in FIG.
A) and a side view (B).

FIG. 4 is a front view showing a modification of the assembled battery shown in FIG. 3;

[Explanation of symbols]

1 Negative electrode 2 Positive electrode 5 Battery case 15　　　　Wound electrode body (electrode body) 17 Aluminum layer 41 First battery 41b Negative electrode terminal part (electrode terminal part) 42 Second battery 50, 51 Assembled battery

Claims (4)

[Claims] 1. An electrode body comprising a negative electrode and a positive electrode, a battery case housing the electrode body and to which the positive electrode is electrically connected, and a battery case provided on one end side of the battery case and having the negative electrode. A secondary battery each comprising an electrode terminal portion to be electrically connected. 2. The secondary battery according to claim 1, wherein the negative electrode and the positive electrode in the electrode body are each configured to be capable of doping and dedoping lithium, and a non-aqueous electrolyte is contained in the battery case. and the inner surface of the battery case is covered with an aluminum material. 3. In the first secondary battery according to claim 1 and the electrode body according to claim 1, the negative electrode is electrically connected to the battery case, and the positive electrode is electrically connected to the electrode terminal portion. An assembled battery comprising a second secondary battery configured to be connected to each other. 4. A first secondary battery according to claim 2, an electrode body according to claim 2, a battery case housing this electrode body and to which the negative electrode is electrically connected, and this battery. and a second secondary battery, each comprising an electrode terminal portion provided on one end side of the can and to which the positive electrode is electrically connected, and a second secondary battery containing a non-aqueous electrolyte in the battery can. Assembled battery.