JPH0935749A - Polymer electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte secondary battery with small size and high capacity by stacking and spirally winding a positive current collector, a negative current collector, a positive electrode layer, a negative electrode layer, a solid polymer electrolyte later, and an insulator layer, then housing a unit cell obtained in a container. SOLUTION: A positive current collector 3, a positive electrode layer 4, a solid polymer electrolyte layer 5, a negative electrode layer 6, a negative current collector 7, and an insulator layer 8 are stacked in this order, then spirally wound to manufacture a unit cell 2. The positive electrode layer 4 contains an active material such as LiMn2 O4 , a nonaqueous electrolyte comprising a solvent such as EC containing an electrolyte such as LiClO4 , and a polymer such as vinylidene fluoride- hexafluoropropylene copolymer for holding the nonaqueous electrolyte. The solid polymer electrolyte 5 contains the nonaqueous electrolyte and the polymer. The negative electrode layer 6 contains a carbon material layer capable of absorbing/releasing a lithium ion, the nonaqueous electrolyte, and the polymer, and the positive current collector 3 is made of an aluminum foil or the like, and the negative current collector 7 is made of a copper foil or the like. The unit cell 2 is housed in a container 1, and a sealing cover group 10 is set to the opening of the container 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymer electrolyte secondary battery provided with a solid polymer electrolyte layer.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a secondary battery that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. As such a secondary battery, a lithium secondary battery including a negative electrode using lithium or a lithium alloy as an active material and a positive electrode using an oxide, sulfide, or selenide such as molybdenum, vanadium, titanium, or niobium as an active material is used. Secondary batteries are known.

However, a secondary battery provided with a negative electrode using lithium or a lithium alloy as an active material has a problem of short charge / discharge cycle life because dendrite of lithium is generated in the negative electrode when the charge / discharge cycle is repeated. .

From the above, a lithium ion secondary battery using a carbonaceous material which absorbs and releases lithium ions such as coke, graphite, carbon fiber, a resin fired body, and pyrolytic vapor phase carbon for the negative electrode is obtained. Proposed. In the lithium ion secondary battery, deterioration of negative electrode characteristics due to dendrite deposition can be improved, so that battery life and safety can be improved.

A polymer electrolyte secondary battery, which is an example of a lithium ion secondary battery, is disclosed in US Pat. No. 5,296,96.
No. 318 discloses a rechargeable lithium intercalation battery having a hybrid polymer electrolyte to which flexibility is imparted by adding a polymer to a positive electrode, a negative electrode and an electrolyte layer. This battery comprises a positive electrode current collector, a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution, and a solid polymer electrolyte layer having a non-aqueous electrolytic solution and a polymer holding the electrolytic solution. A negative electrode layer having a carbonaceous material capable of inserting and extracting lithium ions, a non-aqueous electrolytic solution, and a polymer holding the electrolytic solution, and a negative electrode current collector are laminated in this order.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polymer electrolyte secondary battery having a small size and a high capacity by forming a unit cell in a spiral structure.

[0007]

The polymer electrolyte secondary battery of the present invention comprises a positive electrode current collector, a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution, and a non-aqueous electrolytic solution. And a solid polymer electrolyte layer containing a polymer that holds the electrolytic solution, a carbonaceous material that absorbs and releases lithium ions, a negative electrode layer that includes a non-aqueous electrolytic solution and a polymer that holds the electrolytic solution, and a negative electrode current collector. 5 stacked in this order
A unit cell having a structure formed by disposing an insulating layer on the positive electrode current collector side of the layered laminate or on the negative electrode current collector side and winding these in a spiral shape, and a container in which the unit cell is housed. It is characterized by having.

The polymer electrolyte secondary battery of the present invention holds a positive electrode current collector, a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution, a non-aqueous electrolytic solution and the electrolytic solution. A solid polymer electrolyte layer containing a polymer to
On the positive electrode current collector side of a five-layer laminate in which a negative electrode layer containing a carbonaceous material that absorbs and releases lithium ions, a non-aqueous electrolytic solution, and a polymer that holds this electrolytic solution, and a negative electrode current collector are laminated in this order. A unit cell having a structure in which an insulating layer is arranged and wound in a spiral shape so that the negative electrode current collector is located on the outermost periphery thereof, and the unit cell is housed and also serves as a negative electrode terminal. And a container.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A polymer electrolyte secondary battery according to the present invention will be described below with reference to FIGS. 1 and 2. As shown in FIG. 1, a unit cell 2 is housed in a bottomed cylindrical container 1 that also serves as a negative electrode terminal. The unit cell 2 is shown in FIG.
As shown in FIG. 5, a positive electrode current collector of a five-layer laminate in which a positive electrode current collector 3, a positive electrode layer 4, a solid polymer electrolyte layer 5, a negative electrode layer 6, and a negative electrode current collector 7 are laminated in this order. Insulating layer 8 on 3 side
And are wound in a spiral shape so that the negative electrode current collector 7 is located outside. In such a unit cell 2, the negative electrode current collector 7 is located on the outermost periphery, and the current collector is in electrical contact with the inner surface of the container. A unit cell holding plate 9 made of an insulating material having a through hole 9a opened
Is arranged above the unit cell 2 in the container 1.

Sealing lid group 10 which also has an explosion-proof function and a terminal
Is caulked and fixed to the opening of the container 1 through an insulating gasket 11. The sealing lid group 10 includes a conductive plate 12 arranged to face the unit cell 2, a synthetic resin valve film 13 arranged on the conductive plate, and a metal plate arranged on the valve film 13. The sealing plate 14 and the conductive plate 12,
A cap-shaped terminal 15 inserted into the valve membrane 13 and the sealing plate 14 for electrically connecting the conductive plate 12 and the sealing plate 14, and an annular PTC element arranged on the sealing plate 14. 16 and a cap-shaped positive electrode terminal 18 which is disposed on the PTC element 16 with its peripheral edge portion abutting and has a plurality of gas vent holes 17 formed therein. The conductive plate 1
2 has a plurality of gas vent holes 19 arranged in an annular shape. A plurality of gas vent holes 20 are opened in the sealing plate 14 so as to face the gas vent holes 19. The valve membrane 13 located between the gas vent hole 19 and the gas vent hole 20 is formed with circular recesses 21 arranged at a desired distance from each other. The positive electrode lead 22 is
One end of the holding plate 9 is connected to the positive electrode current collector 3 of the unit cell 2 through the through hole 9a, and the other end is connected to the lower surface of the conductive plate 12 of the sealing lid group 10.
The insulating plate 23 is arranged at the bottom of the container 1 and prevents the positive electrode layer 4 of the unit cell 2 from electrically contacting the container 1 also serving as the negative electrode terminal.

In such a structure, when gas is generated in the secondary battery and this gas pressure is applied to the valve membrane 13 located between the circular recesses 21 through the gas vent hole 19 of the conductive plate 12, this gas The leaflet at the location is broken. Therefore, the gas escapes to the outside through the gas vent hole 20 of the sealing plate 14 and the gas vent hole 17 of the positive electrode terminal 18 from this break point, and a burst is avoided.

Next, the solid polymer electrolyte layer, the positive electrode current collector, the positive electrode layer, the negative electrode current collector, the negative electrode layer and the insulating layer will be described. 1) Solid Polymer Electrolyte Layer This polymer electrolyte layer contains a non-aqueous electrolytic solution and a polymer that holds this electrolytic solution.

The non-aqueous electrolytic solution is prepared by dissolving an electrolyte in a non-aqueous solvent. As the non-aqueous solvent,
Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DME), diethylene carbonate (D
EC), methylene ethylene carbonate (MEC), γ
-Butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxymethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like can be mentioned. The non-aqueous solvent may be used alone,
You may use it in mixture of 2 or more types.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (L
iPF _6), boric tetrafluoride lithium (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium trifluoromethanesulfonate (LiCF ₃ SO _3), bis (trifluoromethylsulfonyl) imide lithium [LiN
(CF ₃ SO ₂ ) ₂ ] and the like.

The amount of the electrolyte dissolved in the non-aqueous solvent is preferably 0.2 mol / l to 2 mol / l. A copolymer of vinylidene fluoride (VdF) -hexafluoropropylene (HFP) can be used as the polymer holding the non-aqueous electrolyte. In the copolymer, VdF contributes to the improvement of mechanical strength in the skeleton of the copolymer, and HFP is incorporated in the copolymer in an amorphous state to retain the non-aqueous electrolyte solution and to remove lithium ions. It functions as a transparent part. The copolymerization ratio of the HFP is
Maximum 20% by weight, although depending on the synthesis conditions
Before and after. 2) Positive Electrode Current Collector As the current collector, for example, aluminum foil, aluminum mesh, or the like can be used. 3) Positive Electrode Layer The positive electrode layer contains an active material, a non-aqueous electrolytic solution, and a polymer that holds the electrolytic solution.

As the active material, various oxides (for example, lithium manganese composite oxides such as LiMn ₂ O ₄ ,
Manganese dioxide, lithium-containing nickel oxide such as LiNiO ₂ , lithium-containing cobalt oxide such as LiCoO ₂ , lithium-containing nickel cobalt oxide, amorphous vanadium pentoxide containing lithium, etc.)
And chalcogen compounds (for example, titanium disulfide, molybdenum disulfide, and the like). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.

The positive electrode permits the use of artificial graphite, carbon black (such as acetylene black), nickel powder, etc. as a conductive material. As the non-aqueous electrolyte and the polymer, the same ones as those described in the solid polymer electrolyte layer described above are used. 4) Negative electrode current collector As this current collector, for example, a copper foil, a copper mesh, or the like can be used. 5) Negative Electrode Layer This negative electrode layer contains a carbonaceous material that absorbs and releases lithium ions, a non-aqueous electrolytic solution, and a polymer that holds this electrolytic solution.

Examples of the carbonaceous material that absorbs and releases lithium ions include organic polymer compounds (eg, phenol resin, polyacrylonitrile, cellulose).
Examples of the carbonaceous material include a material obtained by firing a coke, a coke, a material obtained by firing a pitch, an artificial graphite, a natural graphite, and the like. Above all, it is preferable to use a carbonaceous material obtained by calcining the organic polymer compound at a temperature of 500 ° C. to 3000 ° C. in an inert gas atmosphere such as an argon gas or a nitrogen gas at normal pressure or reduced pressure. preferable.

As the non-aqueous electrolytic solution and the polymer, the same ones as those described for the solid polymer electrolyte layer are used. 6) Insulating Layer This insulating layer is arranged on the positive electrode current collector side of the 5-layer laminate.

For the insulating layer, for example, a film or sheet made of an insulating synthetic resin is fixed to the positive electrode current collector by thermocompression bonding, adhesion, or the like, or an insulating synthetic resin is used for the positive electrode current collector. It can be formed by a method of coating on the above. As the film or sheet made of the insulating synthetic resin, for example, an ionomer resin sheet (for example, Himilan sheet which is a product manufactured by DuPont), polyethylene, polypropylene, or a sheet made of a resin obtained by introducing a polar group into these is used. Etc. can be mentioned. Examples of the insulating synthetic resin applied on the current collector include vinylidene fluoride-hexafluoropropylene (VdF-HFP) copolymer, polyvinylidene fluoride (PVdF), and ethylene-propylene-diene. A terpolymer or the like can be used.

According to the polymer electrolyte secondary battery of the present invention, the positive electrode current collector, the positive electrode layer, the solid polymer electrolyte layer, the negative electrode layer, and the negative electrode current collector are laminated in this order.
A unit cell having a structure formed by forming an insulating layer on the positive electrode current collector side of the layer stack or on the negative electrode current collector side and winding these in a spiral shape, and a container in which the unit cell is housed. Prepare In the unit cell having such a structure, since the insulating layer is interposed between the positive electrode current collector and the negative electrode current collector, an internal short circuit caused by contact between the positive electrode current collector and the negative electrode current collector is prevented. It can be avoided. Therefore, when the unit cell is housed in the container and assembled, a compact and high-capacity polymer electrolyte secondary battery can be realized.

In addition, in FIG. 1 and FIG.
A secondary battery including a unit cell having a structure in which the insulating layer is arranged on the positive electrode current collector side of the layer stack, and the negative electrode current collector is positioned on the outermost periphery of the insulating layer so as to be spirally wound. Although the applied example has been described, the insulating layer is arranged on the negative electrode current collector side of the five-layer laminate, and the unit cell is manufactured by spirally winding so that the insulating layer is located at the outermost periphery thereof, This may be housed in a container that also serves as the negative electrode terminal to assemble the secondary battery. In such a secondary battery, since the inner surface of the container and the insulating layer are in contact with each other, current collection of the negative electrode should be performed by connecting the bottom of the container to the negative electrode current collector of the unit cell with a lead. You can go by.

[0023]

As described above in detail, according to the present invention, it is possible to provide a small-sized and high-capacity cylindrical polymer electrolyte secondary battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a polymer electrolyte secondary battery according to the present invention.

FIG. 2 is a perspective view showing a unit cell incorporated in the secondary battery of FIG.

[Explanation of symbols]

1 ... Container, 2 ... Unit cell, 3 ... Positive electrode collector, 4 ... Positive electrode layer,
5 ... Solid polymer electrolyte layer, 6 ... Negative electrode layer, 7 ... Negative electrode collector, 8 ... Insulating layer, 10 ... Sealing lid group, 11 ... Insulating gasket.

Claims (2)

[Claims] 1. A positive electrode current collector, a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution, and a solid polymer electrolyte layer containing a non-aqueous electrolytic solution and a polymer holding the electrolytic solution. And a negative electrode layer containing a carbonaceous material that absorbs and releases lithium ions, a non-aqueous electrolyte, and a polymer that holds this electrolyte, and a negative electrode current collector. A unit cell having a structure made by disposing an insulating layer on the body side or on the side of the negative electrode current collector and spirally winding the insulating layer, and a container accommodating the unit cell. Polymer electrolyte secondary battery. 2. A positive electrode current collector, a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution, and a solid polymer electrolyte layer containing a non-aqueous electrolytic solution and a polymer holding the electrolytic solution. And a negative electrode layer containing a carbonaceous material that absorbs and releases lithium ions, a non-aqueous electrolyte, and a polymer that holds this electrolyte, and a negative electrode current collector. A unit cell having an insulating layer disposed on the body side and having a structure formed by spirally winding these so that the negative electrode current collector is located at the outermost periphery thereof, and the unit cell is housed and the negative electrode terminal A polymer electrolyte secondary battery comprising a container that also functions as a battery.