JPH0935747A - Polymer electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte secondary battery which is easy to assemble a pack battery by embedding positive and negative terminals in a frame body for housing a polymer electrolyte unit cell comprising a positive electrode layer, a negative electrode layer, and a polymer electrolyte layer interposed between both electrode layers. SOLUTION: A positive electrode layer containing an active material, a nonaqueous electrolyte, and a polymer which holds the nonaqueous electrolyte is stacked on a current collector to obtain a positive electrode. A negative electrode layer containing a carbon material capable of absorbing/releasing a lithium ion and holding the nonaqueous electrolyte is stacked on a current collector to obtain a negative electrode layer. A solid polymer electrolyte layer containing the nonaqueous electrolyte and a polymer for holding the nonaqueous electrolyte is interposed between the positive electrode layer and the negative electrode layer to obtain a polymer electrolyte unit cell 2. The polymer electrolyte unit cell 2 is housed in a frame body 8 made of an insulating material, and sealed with upper and lower covers 13, 14. Socket type terminals 9, 10 electrically connected to the positive and negative current collectors through lead wires 11, 12 are inserted from its one side into the frame body 8 and embedded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte secondary battery, and more particularly to a polymer electrolyte secondary battery having an improved terminal structure for externally connecting a built-in polymer electrolyte battery.

[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 that the charge / discharge cycle life is short because lithium dendrites are generated in the negative electrode when charge / discharge cycles are repeated.

[0003] For this reason, the negative electrode, for example coke, graphite, carbon fiber, resin fired body, a lithium ion, such as pyrolytic vapor carbon using a carbonaceous material for absorbing and releasing, electrolytes such as LiPF ₆ A non-aqueous solvent secondary battery using an electrolytic solution comprising a non-aqueous solvent such as ethylene carbonate and propylene carbonate has been proposed.
The non-aqueous solvent secondary battery can improve the negative electrode characteristics due to the precipitation of dendrite, and thus can improve the battery life and safety.

On the other hand, US Pat. No. 5,296,318 discloses a rechargeable lithium intercalation having a hybrid polymer electrolyte which has been made flexible by adding polymers to the cathode, anode and electrolyte layers. A battery, that is, a polymer electrolyte secondary battery is disclosed. Such a polymer electrolyte secondary battery has an active material,
A positive electrode in which a positive electrode layer containing a non-aqueous electrolytic solution and a polymer holding the electrolytic solution is laminated on a current collector, a carbonaceous material capable of inserting and extracting lithium ions, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution. An element having a structure including a negative electrode having a negative electrode layer laminated on a current collector, and a non-aqueous electrolytic solution interposed between the positive electrode layer and the negative electrode layer and a solid polymer electrolyte layer containing a polymer holding the electrolytic solution. Equipped with batteries.

By the way, as one of the uses of the unit cell, for example, it is considered that two unit cells are housed in a container made of synthetic resin so as to be connected to each other in series to assemble an assembled battery (pack battery). There is. To construct such an assembled battery, it is necessary to attach leads and the like for connecting to the terminals in the container to the positive and negative electrode current collectors of the unit cells.

However, since the unit cell has flexibility and low strength, if it is pulled for the purpose of connecting the lead to the terminal in the container, the lead is connected to the positive and negative electrode current collector. There was a problem of damage.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer electrolyte secondary battery which has positive and negative electrodes and is easy to assemble an assembled battery or the like.

[0008]

A polymer electrolyte secondary battery according to the present invention comprises a positive electrode in which a positive electrode layer containing an active material, a nonaqueous electrolytic solution and a polymer holding the electrolytic solution is laminated on a current collector, and a lithium A negative electrode containing a carbonaceous material that absorbs and releases ions, and a negative electrode layer that holds a non-aqueous electrolyte solution is laminated on a current collector; a non-aqueous electrolyte solution interposed between the positive electrode layer and the negative electrode layer; and A polymer electrolyte cell having a solid polymer electrolyte layer containing a polymer holding an electrolyte solution;
A frame body made of an insulating material surrounding the unit cell; positive and negative electrode terminal portions embedded in the frame body and electrically connected to a positive electrode current collector and a negative electrode current collector of the unit cell; It is characterized in that it is provided with lids attached to the upper and lower surfaces, respectively.

[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. The polymer electrolyte secondary battery 1 includes a rectangular flat polymer electrolyte battery 2 as shown in FIG. As shown in FIG. 3, the unit cell 2 includes a positive electrode having a structure in which a positive electrode layer 4 is laminated on a current collector 3 made of, for example, an aluminum foil, a net made of aluminum or an expanded metal, a copper foil, and a net made of copper. Alternatively, it is composed of a negative electrode having a structure in which a negative electrode layer 6 is laminated on a current collector 5 made of expanded metal, and a solid polymer electrolyte layer 7 interposed between the positive electrode layer 4 of the positive electrode and the negative electrode layer 6 of the negative electrode. Has been done.

The frame 8 made of an insulating material is used for the unit cell 2
Is enclosed and surrounds the unit cell 2. The socket-shaped positive electrode terminal 9 and the negative electrode terminal 10 are inserted and embedded in one side of the frame body 8 from the side surface. The positive and negative marks are drawn on the side surface of the frame body 8 in which the terminals 9 and 10 are embedded. The positive and negative marks are also drawn on the side surface of the frame body 8 in which the terminals 9 and 10 are embedded so as to face the positive and negative marks. One end of the positive electrode lead 11 is connected to the positive electrode current collector of the unit cell 2, and the other end is connected to the rear end of the positive electrode terminal 9 exposed on the inner surface side of the frame body 8. Negative electrode lead 1
2, the negative electrode terminal 10 has one end connected to the negative electrode current collector of the unit cell 2 and the other end exposed on the inner surface side of the frame body 8.
It is connected to the rear end of. The upper surface of the positive electrode lead 11 excluding the connection part between the positive electrode current collector and the positive electrode terminal 9 is preferably covered with an insulating layer to prevent contact with the negative electrode current collector of the unit cell 2. . Also,
It is desirable that the upper surface of the negative electrode lead 12 excluding the connection portion between the negative electrode current collector and the negative electrode terminal 10 is covered with an insulating layer to prevent contact with the negative electrode current collector of the unit cell 2.

The lids 13 and 14 are attached to the upper and lower surfaces of the frame body 8, respectively. Next, the above-mentioned positive electrode layer 4, negative electrode layer 6, solid polymer electrolyte layer 7, frame 8 and lids 13 and 14 will be described in detail.

1) Positive Electrode Layer This positive electrode layer contains an active material, a conductive material, a non-aqueous electrolytic solution and a polymer which holds this electrolytic solution.

Examples of the active material include lithium-containing nickel oxide such as lithium-manganese composite oxide, manganese dioxide, and Li _y NiO ₂ (where y is an atomic ratio of 0.05 <y ≦ 1.0). things, Li _y CoO ₂ (Here, y is 0.05 <y ≦ 1.0 in atomic ratio) of lithium-containing cobalt oxides such as, Li _y Co _z Ni
_1-z O ₂ (where y and z are each 0.05 in atomic ratio)
<Y ≦ 1.0, 0 <z <1.0), various oxides such as amorphous vanadium pentoxide containing lithium, titanium disulfide, and disulfide. Chalcogen compounds such as molybdenum can be used. In particular, a lithium manganese composite oxide is preferable. Among such lithium manganese composite oxides, it is preferable to use one having a composition formula represented by Li _x Mn ₂ O ₄ (where x is an atomic ratio of 0.05 <x ≦ 2.0). A polymer electrolyte secondary battery provided with a positive electrode containing a lithium manganese composite oxide having such a composition has improved discharge capacity.

As the conductive material, for example, carbon black such as artificial graphite and acetylene black can be used. The electrolytic solution is prepared by dissolving an electrolyte in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2 -Methyltetrahydrofuran, γ-butyrolactone and the like can be mentioned. The non-aqueous solvent may be used alone or in combination of two or more.

Examples of the electrolyte contained in the non-aqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), and lithium arsenide hexafluoride (LiBF ₄ ). LiAsF
₆ ), lithium trifluorometasulfonate (LiCF
₃ SO ₃ ) and lithium bis (trifluoromethylsulfonylimide) [LiN (CF ₃ SO ₂ ) ₂ ].

The amount of the electrolyte dissolved in the non-aqueous solvent is desirably 0.5 to 2.0 mol / l. As the polymer, for example, a copolymer of vinylidene fluoride-hexafluoropropylene (VDF-HFP) can be used. In such a copolymer,
VDF contributes to the improvement of mechanical strength at the skeleton portion of the copolymer, and HFP is taken into the copolymer in an amorphous state and functions as a holding portion for the electrolyte and as a lithium ion transmitting portion. The copolymerization ratio of the HFP depends on the method of synthesizing the copolymer, but is usually at most about 20% by weight.

2) Negative Electrode Layer 6 The negative electrode layer 6 contains a carbonaceous material which absorbs and releases lithium ions, a non-aqueous electrolytic solution and a polymer which holds this electrolytic solution.

Examples of the carbonaceous material include those obtained by firing organic polymer compounds (for example, phenol resin, polyacrylonitrile, cellulose, etc.), those obtained by firing coke and pitch, and those obtained by mesophase. Examples thereof include those obtained by firing pitch, artificial graphite, and natural graphite. Above all, in an atmosphere of an inert gas such as argon gas or nitrogen gas, 500 ° C. to 300 ° C.
It is preferable to use a carbonaceous material obtained by firing the organic polymer compound at a temperature of 0 ° C. under normal pressure or reduced pressure.

As the non-aqueous electrolyte and the polymer, the same ones as described for the positive electrode layer described above are used. 3) Polymer Electrolyte Layer 7 This polymer electrolyte layer 7 contains a non-aqueous electrolytic solution and a polymer that holds this electrolytic solution.

As the non-aqueous electrolyte and the polymer, the same ones as described for the positive electrode layer are used. 4) Frame 8 The frame 8 is made of thermosetting resin such as epoxy resin, thermoplastic resin such as nylon or polyethylene, or synthetic rubber such as acrylic rubber, isoprene rubber, or styrene-butadiene rubber. To be done. In particular, by forming the frame body 8 from rubber, it is possible to realize a polymer electrolyte secondary battery utilizing the flexibility of the unit cell 2.

5) Lids 13 and 14 The lids 13 and 14 are, for example, a metal plate such as a copper plate or a nickel-plated stainless steel plate, or a metal plate whose one surface is covered with an insulating film such as a synthetic resin film, or It is formed of a synthetic resin plate with an aluminum foil interposed therebetween.

In the polymer electrolyte secondary battery 1 having the configuration shown in FIGS. 1 to 3 described above, the polymer electrolyte unit cell 2 and the frame 8 made of an insulating material surrounding the unit cell 2 are provided.
And is inserted by being inserted into one side of this frame body 8 from the side surface,
Socket-shaped positive and negative electrode terminals 9 and 10 connected to the positive and negative electrode current collectors of the unit cell 2 by leads 11 and 12, respectively. Such a polymer electrolyte secondary battery 1 can prevent damage at a lead wire connecting portion such as a secondary battery in which a lead wire is directly connected to a unit cell, and has high reliability. Further, the polymer electrolyte secondary battery 1 is shown in FIGS.
Battery storage container 2 having two battery storage parts as shown in FIG.
A battery pack can be realized by storing the battery pack in one.

That is, the battery storage container 21 in FIG. 4 has a box shape with an open front surface, and has first and second battery storage portions 23 ₁ and 23 ₂ which are vertically divided by a partition plate 22. The projecting first positive and negative electrode terminals 24 ₁ and 25 ₁ are planted side by side in the horizontal direction on the back wall portion of the container 21 forming the first battery housing portion 23 ₁ . The second positive and negative electrode terminals 24 ₂ and 25 ₂ having a projecting shape are provided in the second battery storage portion 23 _2.
Are planted side by side in the horizontal direction on the back wall of the container 21 forming the. As shown in FIG. 5, positive and negative terminals 24 ₁ , 24 ₂ , 25 ₁ , 2 are formed on the outer surface of the back wall of the container 21.
5 the rear end of the ₂ is projected. The positive and negative terminals 24
Lands 26 to 29 are formed on the outer surface of the back wall portion including the rear end portions of ₁ , 24 ₂ , 25 ₁ and 25 ₂ .
The land 26 around the first positive electrode terminal 24 ₁ is
The land 29 around the negative electrode terminal 25 ₂ and the wiring layer 30 are connected to each other. The spring-type contact (not shown) is used for the land 2 around the first positive and negative terminals 24 ₁ and 25 _1.
6 and 27, respectively.

In the battery container 21 having such a structure, as shown in FIG. 4, the polymer electrolyte secondary battery 1 includes the socket-shaped positive and negative terminals 9 and 10 of the secondary battery 1 as the container 2.
1 so as to face the opening side of the first battery compartment 23 ₁
, The first positive and negative electrode terminals 24 ₁ and 25 ₁ in the form of sockets, which are planted side by side in the horizontal direction on the back wall of the container 21 forming the first battery housing 23 ₁ , are socket-shaped positive and negative. The pole terminals 9 and 10 are fitted and connected. Similarly, by inserting the second polymer electrolyte secondary battery into the second battery housing portion 23 ₂ of the container 21, the positive and negative terminals of the secondary battery are connected to the second positive and negative terminals 24 ₂ and 25 _2. The pole terminals are fitted and connected. Therefore, the two polymer electrolyte secondary batteries 1 are stored in the first and second battery storage portions 23 ₁ and 23 ₂ of the battery storage container 21, respectively, and the positive and negative electrode terminals 24 ₁ , 24 ₂ and 2 are stored.
5 _1, the topology of the land 26 to 29 and the wiring layer 30 of 25 ₂ of the rear end the container 21 rear wall portion formed around two of the secondary battery can be realized serially connected battery assembly .

Although the socket type positive and negative electrode terminals are embedded in the frame in FIGS. 1 to 3 described above, a positive and negative electrode terminal of another type such as a pin type may be embedded. Further, in FIG. 5 described above, an assembled battery in which two polymer electrolyte secondary batteries are housed in a battery container is connected in series according to the connection form of the land and the wiring layer is assembled, but is not limited thereto. For example, as shown in FIG. 6, positive and negative electrode terminals 24 ₁ , 24 are formed on the outer surface of the back wall of the container 21.
₂ , the rear ends of 25 ₁ , 25 ₂ are projected, and lands 26-29 are formed on the outer surface of the back wall portion including the rear ends of the positive and negative terminals 24 ₁ , 24 ₂ , 25 ₁ , 25 _2. , And the land 2 surrounding the _first and _second positive electrode terminals 24 ₁ and 24 2.
6 and 28 are connected to each other by a wiring layer 31, and the lands 27 and 29 around the _first and _second negative electrode terminals 25 ₁ and 25 ₂ are connected to each other by a wiring layer 32. When the battery 1 is stored in each of the first and second battery storage portions of the battery storage container 21, an assembled battery in which two secondary batteries are connected in parallel can be realized.

[0027]

As described in detail above, according to the present invention, it is possible to provide a polymer electrolyte secondary battery having positive and negative electrodes and easy to assemble an assembled battery or the like.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a polymer electrolyte secondary battery according to the present invention.

FIG. 2 is a perspective view showing the polymer electrolyte secondary battery of FIG.

3 is a partially cutaway perspective view showing a unit cell incorporated in the polymer electrolyte secondary battery of FIG.

FIG. 4 is a perspective view for explaining how to store a battery container and a polymer electrolyte secondary battery in the container.

5 is a front view showing the structure of the back wall portion of the container of FIG.

6 is a front view showing another structure of the back wall portion of the container of FIG. 4. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polymer electrolyte secondary battery, 2 ... Polymer electrolyte battery 3, 5 ... Current collector, 4 ... Positive electrode layer, 6 ... Negative electrode layer, 7 ... Polymer electrolyte layer, 8 ... Frame body, 9, 10 ... Socket type Terminals, 11, 12 ... Lead wires, 21 ... Battery storage container, 23
₁ , 23 ₂ ... Battery storage part, 24 ₁ , 24 ₂ , 25 ₁ , 2
5 ₂ ... protruding terminal, 26-29 ... land, 30 to 32
… Wiring layer.

Claims (1)

[Claims] 1. A positive electrode in which a positive electrode layer containing an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution is laminated on a current collector, and a carbonaceous material which absorbs and releases lithium ions,
A solid polymer electrolyte containing a negative electrode in which a negative electrode layer holding a non-aqueous electrolyte solution is laminated on a current collector, and a non-aqueous electrolytic solution interposed between the positive electrode layer and the negative electrode layer and a polymer holding the electrolytic solution. A polymer electrolyte unit cell having a layer; a frame made of an insulating material surrounding the unit cell; embedded in the frame body, and electrically connected to a positive electrode current collector and a negative electrode current collector of the unit cell, respectively. A polymer electrolyte secondary battery, comprising: a positive and negative electrode terminal portion; and a lid body attached to the upper and lower surfaces of the frame body, respectively.