JPH01294373A - Nonaqueous electrolyte-secondary battery - Google Patents

Abstract

PURPOSE:To obtain a nonaqueous electrolyte secondary battery of high reliability which can be repeatedly charged/discharged for a long term by installing negative electrodes composed of organic fired body, positive electrodes including specified lithium compound and electrolyte into a battery-can and providing a specified gap in the can. CONSTITUTION:Installed into a battery-can 1 are negative electrodes 5 composed of organic fired body, positive electrodes 6 including LixMO2 (M being Co or Ni, 0.05<=x<=1.10) and provided in the can is a gap 13 of 0.3cc per capacity 1AH. Thus, even if gas is generated by repeating charging/discharging, the gas is put into the gap, so that the air-pressure in the battery is not so increased that the electrolyte charged in the battery is leaked out or the can 1 is deformed. Accordingly, a nonaqueous electrolyte-secondary battery of high reliability which can be repeatedly charged/discharged for a long term can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a chargeable/dischargeable non-aqueous electrolyte secondary battery used as a power source for various electronic devices.

<Summary of the Invention> The present invention provides a negative electrode made of a fired organic material, and a Li
(M represents at least one kind of CO or Ni, 0.05
≦λ≦1.10. ) and an electrolyte are housed in a container. By providing a gap of 3 cc or more per 1 AH of capacity in a non-aqueous electrolyte secondary battery, the gas generated during charging can be This aims to provide a highly reliable non-aqueous electrolyte secondary battery by preventing deformation of the battery or leakage of the electrolyte.

<Conventional technology> Conventionally, so-called non-aqueous electrolyte batteries that use light metals such as lithium or lithium alloys as negative electrode materials and organic electrolytes as electrolytes have been used because of their high operating voltage and extremely excellent storage stability. As a battery with long-term reliability, it is widely used as a power source for electronic watches and various memory bank ups.

However, these currently used non-aqueous electrolyte batteries are used only as primary batteries, and their lifespan ends after one use, so there are points that need to be improved from an economic standpoint.

Therefore, along with the rapid progress of various electronic devices in recent years, the emergence of rechargeable non-aqueous electrolyte secondary batteries as a power source that can be used conveniently and economically for long periods of time has been awaited, and much research has been carried out. is in progress.

In general, negative electrode active materials for nonaqueous electrolyte secondary batteries include metallic lithium, lithium alloys (e.g., Li-Al alloys),
Conductive polymers doped with lithium ions (e.g. polyacetylene, polypyrrole, etc.), and even compounds with lithium ions mixed into their crystals are used, and the electrolyte is a nonaqueous solution in which the electrolyte is dissolved in an organic solvent An electrolyte is used.

On the other hand, various materials have been proposed as positive electrode active materials as a result of research, and representative ones include, for example,
As described in Publication No.-54836, TiS2, M
Examples include oS2, NbSe2, and V205.

The discharge reaction of batteries using these materials proceeds as lithium ions in the negative electrode intercalate between the eyebrows of the positive electrode active material, and conversely, when charging, lithium ions deplete from the eyebrows of the materials to the negative electrode. Intercalate. In other words, by repeating the reaction in which lithium ions in the negative electrode move in and out between the layers of the positive electrode active material,
Can be repeatedly discharged and charged.

<Problems to be Solved by the Invention> However, as described above, for example, metallic lithium is used as the negative electrode active material, MoS2 is used as the positive electrode active material, or Li-A6 alloy is used as the negative electrode active material.

When a lithium battery is made using TiS2 etc. as a positive electrode active material, as the discharge and charging proceed, Li and L1
-Aj! The problem is that the alloy deteriorates and becomes powdery, making it impossible to use it for a long period of time.

Therefore, in order to solve these problems, it has been proposed to use an organic fired body as an electrode material, and as a positive electrode active material, L1χCo02 (χ=0 .05 to 1.10).

However, when such a fired organic material is used as a negative electrode material, Li x COO2 (X = 0.05 to 1.1
If 0) is used, gas is generated during charging, and the increase in internal pressure caused by the gas generation causes leakage of the electrolyte and damage to the battery, resulting in practical inconveniences.

Therefore, the present invention prevents electrolyte leakage and battery damage caused by gas generated by repeated charging and discharging of a non-aqueous electrolyte secondary battery as described above, and makes it possible to repeat charging and discharging for a long period of time. This was proposed with the aim of providing a highly reliable non-aqueous electrolyte secondary battery.

<Means for Solving the Problems> In order to achieve the above object, the present invention uses a negative electrode made of a fired organic material, and Li we MO2 (M is C).

or represents at least one type of Ni, and 0.05≦≦1.
It is 10. ) and an electrolytic solution are housed in a container.
It is characterized by having a gap of cc or more.

The negative electrode of the nonaqueous electrolyte secondary battery according to the present invention uses a fired organic material as an electrode active material. Examples of materials for the fired organic material that satisfy the conditions of the present invention include thermal decomposition of various organic compounds. An example of the above-mentioned organic material fired material of the present invention that can be obtained by firing or carbonization is vapor-grown carbon fiber. This vapor-grown carbon fiber is a carbon material obtained by subjecting carbon compounds such as benzene, methane, and carbon oxide to vapor-phase thermal decomposition in the presence of a transition metal catalyst, etc., using a known method similar to this. It refers to everything that can be obtained by. It is usually obtained in the form of fibers, that is, carbon fibers, by such a method, and it may be used as it is, or it may be used in the form of pulverized powder. Other examples include pitch-based carbonaceous materials. - Examples include petroleum pitch, asphalt pitch, coal tar pitch, crude oil cracked pitch, petroleum sulfate such as petroleum pitch, pinch obtained by thermal decomposition of carbon, hydrochloride obtained by thermal decomposition of high molecular weight polymers, and tetrabenzophenazine. Examples include pitch obtained by thermal decomposition of organic low-molecular compounds such as. Furthermore, pitch-based calcined carbides such as needle coke and calcined carbides of polymers containing acrylonitrile as a main component can also be used.

On the other hand, in the positive electrode, LixMO2 (M represents at least one transition metal, preferably CO or Ni, 0.05≦
A positive electrode active material containing Z≦1.10>, such as LixCo
02 or L ix N +2 G 0 (1-s) 02 (however, O
:5)<1) A complex oxide is used.

The above-mentioned composite oxide can be obtained by using carbonates of lithium, cobalt, and nickel as starting materials, mixing them according to the composition, and firing the mixture. Of course, the starting materials are not limited to these, and the synthesis can be similarly performed using hydroxides and oxides of these metals. Further, the firing temperature may be appropriately set depending on the starting materials, but is usually in the temperature range of 600°C to 1100°C.

In the resulting composite oxide, cobalt and nickel can be freely replaced depending on the composition of the raw materials, but (in the general formula above)
There is no particular limitation as long as the value of is in the range of 0≦1.

The electrolyte is not particularly limited, but includes, for example, propylene carbonate, ethylene carbonate,
1,2-dimethoxyethane, 1,2-jethoxyethane, T-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3 dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, pro- A single solvent such as pionitrile or a mixture of two or more types can be used.

Any conventionally known electrolytes can be used, including LiC
j! 04. LiAsF6. LiPFe.

LiBF4, LiB (CoHs)4, LiCj! .

L ibr SCH3,! S O3L r, CFs
It is possible to use one kind or a mixture of two or more kinds such as SOa Li.

Further, the separator may be made of any conventionally known insulating material, such as polypropylene, polytetrafluoroethylene, polyethylene, polyacetal, etc.

Further, the gap according to the present invention needs to be provided at least 0.3 cc or more per capacity IAH, and the position of the gap is not limited.

Since the above-mentioned void is determined by the amount of gas generated by charging and discharging, it is necessary that the void be large enough to accommodate a small amount of gas (at least the same amount of gas as the amount of gas), but conversely, If the gap is too wide, the capacity of the battery will decrease, so the upper limit may be appropriately set so as to provide the required capacity of the battery.

For example, in a so-called jelly-roll type non-aqueous electrolyte secondary battery in which a sheet-shaped negative electrode and a positive electrode are laminated with a separator in between, wound spirally, and housed in an outer can, this gap is located at the center of the inside of the battery. The space can be secured by a cylindrical space formed in the cell, and the size of the space can be adjusted by controlling the amount of electrolyte filled inside the battery.

In addition, in the case of a non-aqueous electrolyte secondary battery of the jelly roll type described above, which has a rectangular parallelepiped appearance and has a plurality of negative electrodes and positive electrodes stacked inside with a separator interposed therebetween, the above-mentioned voids are It can be provided inside the battery, for example, on the upper end side, and its width can be adjusted depending on the volume of the above-mentioned electrodes, electrolyte, etc. to be accommodated.Furthermore, it can be adjusted according to other conditions, such as the size of the gasket. Needless to say, it's a good thing.

Effect> According to the non-aqueous electrolyte secondary battery according to the present invention, even if gas is generated due to repeated charging and discharging, the gas is contained in the gap provided in the container, and the atmospheric pressure inside the battery is The electrolyte stored in the battery does not rise to the extent that it leaks out or becomes deformed.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In this example, the present invention is applied to a non-aqueous electrolyte secondary battery provided with a so-called explosion-proof mechanism.

As shown in FIG. 1, the non-aqueous electrolyte secondary battery according to this example includes a cylindrical outer can (1) in which a power generation element is housed;
A gasket (2) provided on the inner peripheral surface of the upper end of this outer can (1), a safety valve (3) fitted and supported by this gasket (2), and a positive terminal that closes the outer can (1) and The gas kerater (2), the safety valve (3), and the lid (4) are attached to the exterior can (1) by caulking.

Inside the exterior can (1), a negative electrode material (5) and a positive electrode material (6) as a power generating body are housed in a plurality of windings with a separator (7) impregnated with an electrolytic solution (not shown) in between. At the same time, an insulating sheet (8) is placed on the upper side of this power generating body. An insertion hole (10) for inserting a lead terminal (9) is formed in the center of the insulating sheet (8). The lead terminal (9) has one end connected to the positive electrode material (6).
), and the other end is connected to the above insulating sheet (
8) It is attached from the lower surface of the safety valve (3) through the insertion hole (10) to the lower surface of the safety valve (3), which will be described later, by a method such as spot welding.

The center portion where the negative electrode material (5) and the positive electrode material (6) are wound a plurality of times with the separator (7) interposed therebetween is a gap portion (
13). The width of this gap (13) is
It is adjusted by the amount of electrolytic solution impregnated into the separator (7).

On the other hand, there is a large diameter portion (12) on the upper end side of the outer can (1).
is provided, and the gasket (2) is attached to this large diameter portion (12).
) is inserted. A safety valve (3) is provided on the upper surface of the gasket (2). This safety valve (
3) is in the shape of a disc with a diameter slightly shorter than the diameter of the gasket (2), and is fitted into the inner peripheral side of the annular rising portion (2a) formed on the gasket (2). The thickness of this safety valve (3) is the same as that of the outer can (1).
A groove portion (3a) having a thickness that allows gas generated by discharge of the power generator housed therein to rupture if the air pressure inside the battery rises even if the gas is passed through the gap portion (13). is provided. That is, when the air pressure inside the battery exceeds a predetermined value, the safety valve (3) is activated and ruptured. Note that the lead terminal (9) connected to the positive electrode (6) is connected to the lower surface of the safety valve (3).

The safety valve (3) is placed on the top of the safety valve (3).
) A disc-shaped lid body (4) is provided opposite to the lid body (4). This lid (4) functions as the positive terminal of the battery, and has a bulge (4) in the center that bulges upward in Figure 1.
a) is formed, and the safety valve (
3) is in contact with. In addition, two small holes (4b), (4b) are bored in the bulging part (4a) of this lid body (4), so that if the safety valve (3) ruptures as shown in Figure 2, When the gas inside the battery is released to the outside (in the direction of arrow X in Figure 2)
It is designed so that it can be released to

Note that the non-aqueous electrolyte secondary battery according to the above embodiment is provided with an explosion-proof mechanism, and the negative electrode material (5) and the positive electrode material (6) are spirally laminated and wound with a separator (7) in between. Although the present invention is applicable to so-called jelly roll type batteries, the present invention is also applicable to, for example, rectangular type batteries shown in Figs. 3 and 4 in addition to the above-mentioned types. can do.

This non-aqueous electrolyte secondary battery has a generally cubic shape, and a plurality of panels, which are power generators, are inserted into an exterior can (20) through a separator (21) impregnated with an electrolyte (not shown). A negative electrode material (22) and a plurality of positive electrode materials (23) are stored. The above negative electrode material (22) and positive electrode material (23)
The negative electrode material (22) is located on both the left and right sides as shown in FIG. 4, and is in electrical contact with the outer can (20). ing. As shown in FIG. 3, a mouth-shaped insulating plate (24) is formed on the inner peripheral surface of the outer can (20), and the negative electrode material (22) and the positive electrode (23) are connected to the outer can. It is designed to prevent short circuits within the can (20).

Moreover, the upper part of the exterior can (20) is a cavity (25).
is provided. The width of this void (25) is set to at least Q, 3 cc or more per capacity IAH of the non-aqueous electrolyte secondary battery.

A negative electrode lead (26) for electrically connecting each of the plurality of negative electrode materials (22) is disposed within the gap (25). Similarly, the plurality of positive electrode materials (23) are also electrically connected within the cavity (25) by the positive electrode lead (27), and the outer can (20)
) is connected to a positive terminal (28) provided on the upper end surface (20a) of the terminal. In addition, an insulating plate (29) is provided at the upper end of the power generator made of the negative electrode material (22), positive electrode material (23), etc.
is arranged, and the negative electrode lead (26) and the positive electrode lead (
27) are inserted through a plurality of small holes (29a) provided in this insulating plate (29).

In addition, the outer can (
An annular insulating member (30) is disposed on the upper end surface (20a) of the terminal (28) to surround the terminal (28), and connects the outer can (20) serving as the negative terminal and the positive terminal (28).
) to prevent short circuits.

The present inventors created jelly roll type non-aqueous electrolyte secondary batteries equipped with the above-described explosion-proof mechanism under various conditions described below, and also manufactured these batteries under certain conditions described below. The safety valves were repeatedly charged and discharged under various conditions, and the resulting state of the safety valve was observed.

First, as a negative electrode material (1), 90 parts by weight of pulverized pitch coke was mixed with 10 parts by weight of polyfluorocinylidene, and the mixture was dissolved in N-methylpyrrolidone to form a slurry. This slurry was coated on both sides of a copper foil with a thickness of o and otN, and after insertion, it was pressed to a thickness of QJmm.

Width 430. An electrode with a length of 290 mm and a negative electrode mixture weight of 2.6 g was prepared.

Next, as a positive electrode material (6), 91 parts by weight of LiCo02, which was obtained by mixing LiCo3 and COCO3 and calcining it in air at 900°C, were mixed with 6 parts by weight of graphite and 3 parts by weight of polyfluorovinylidene. Melt methylpyrrolidone and make a slurry, apply it to both sides of aluminum foil with a thickness of 0.02mm, insert it and press it to make it 0.0mm thick.
An electrode with a length of 2 m, a diameter of 43 mm, and a length of 290 u was prepared, and the flow rate of the positive electrode mixture was 6.0 g.

Then, a current collecting lead was attached to each of the positive and negative electrodes, and a microporous film with a diameter of 45 mm and a thickness of 0.025 mm was used as a separator.
It was rolled up and assembled into an outer can (1) with an outer diameter of 13.81 m, and a gasket (2) was further inserted. After that, 2.6 ml of an electrolyte prepared by mixing equal volumes of propylene carbide and dimethoxyethane and dissolving 1 mol of LiPF was injected, and the aluminum safety valve (3) and lid body (4) were attached. 3) and the lid (4) were caulked to be tightly sealed to create a non-aqueous electrolyte secondary battery.

The safety valve (3) used in Example 1 has a diameter of about 15
I used one that operates using air pressure.

A non-aqueous electrolyte secondary battery was created under the conditions of the non-aqueous electrolyte secondary battery created in Example 1 above, with the amount of electrolyte injected being 2.5 mol.

Example 111 A non-aqueous electrolyte secondary battery was created under the conditions of the non-aqueous electrolyte secondary battery created in Example 1, with the electrolyte to be injected being 2.3++1.

Implementation ±1 Under the conditions of the non-aqueous electrolyte secondary battery prepared in Example 1, each electrode of the negative electrode (5) and positive electrode (6) was
m to 35.5 gm, and separator (7)
The width of the negative electrode (5), positive electrode (6), and separator (7) are stored in the outer can (1) as in the case of the non-aqueous electrolyte to create a non-aqueous electrolyte secondary battery. did.

In addition, the electrolyte injected into this outer can (1) is 2.8a
+1, and the air gap at this time was set to 1 mol.

Among the conditions of the non-aqueous electrolyte secondary battery prepared in Example 1 above,
A non-aqueous electrolyte secondary battery was created in which no voids were provided within the battery.

, comparison 1 day.

A non-aqueous electrolyte secondary battery was created under the conditions of the non-aqueous electrolyte secondary battery created in Example 1, with the electrolyte to be injected being 2.7+*l.

Examples 1 to 4 and Comparative Examples 1 and 2 of each of the non-aqueous electrolyte secondary batteries created under the conditions described above were discharged at 220 mA.
x 3H hours (maximum voltage 4.OV) charging 14.0Ω
Ten cycles of discharging and charging were repeated under the condition (starting and ending voltage of 1.9 V). Then, the state of each battery after this discharging and charging was observed, and the state of each battery was also observed after each battery was stored at 60° C. for one day after the above-mentioned discharging and charging.

These results are listed in Table 1 below.

(Hereafter, blank space) As is clear from Table 1 above, in the secondary battery according to Example 1, no change was observed in the safety valve (3) after 10 cycles. However, after 10 cycles and storage at 60° C. for one day, the safety valve (3) was deformed into a somewhat convex shape. However, since the safety valve (3) was not operated by internal air pressure and there was no electrolyte leakage, there was no particular problem in practical terms. This is because the temperature of 60°C is close to the highest temperature in practice.

Moreover, the secondary batteries according to Examples 2 to 4 were good, with no change in the safety valve (3) after 10 cycles and no change in the safety valve (3) after 60 days of storage. However, the secondary battery of Example 4 has a capacity of 30OAH.
It had declined to .

On the other hand, in the secondary battery according to Comparative Example 1, the safety valve (3) was deformed by repeating the above 10 cycles of charging and discharging, and furthermore, the safety valve (3) was deformed after being stored at 60°C since no void was provided inside the battery. The capacity obtained by repeated charging and discharging in Comparative Example 1 was 500n.
It was AI.

Furthermore, in the secondary battery of Comparative Example 2 in which a gap of 0.1a+1 was provided, deformation and operation of the safety valve (3) were found as in the secondary battery of Comparative Example 1 described above.

In this way, even if the pressure inside the non-aqueous electrolyte secondary battery 1 increases due to repeated charging and discharging, providing a void inside the battery 1 will prevent the battery 1 from being deformed or The electrolyte filled inside can be prevented from leaking to the outside. In particular, the above air gap is 2χ~10χ with respect to the battery volume, and 3χ~ with respect to the effective volume within the battery.
Approximately 152, or the capacity of a common non-aqueous electrolyte secondary battery 1
By setting the amount per AH to 0.3 cc to 2.0 cc, it is possible to provide a non-aqueous electrolyte secondary battery with excellent capacity.

In addition, although the present invention has been described with reference to examples in which the voids provided inside the battery are adjusted by the amount of electrolyte, the present invention is not limited to the above-mentioned examples, and the present invention is not limited to the above-mentioned examples. It is also possible to adjust by

In addition, in the description of each of the above embodiments, the present invention has been described as a so-called jelly battery, which has a cylindrical external shape and has a power generating body formed by winding a positive electrode and a negative electrode in a product N-wound with a separator interposed inside the battery. Although a roll-type non-aqueous electrolyte secondary battery was used, the present invention is not limited to this type of non-aqueous electrolyte secondary battery; Needless to say, the present invention can be applied to rectangular parallelepiped non-aqueous electrolyte secondary batteries.

<Effects of the Invention> According to the non-aqueous electrolyte secondary battery according to the present invention, even if gas is generated due to repeated charging and discharging, the battery will not deform or the electrolyte filled inside the battery will not deform. Since leakage of the non-aqueous electrolyte to the outside can be prevented, a highly reliable non-aqueous electrolyte secondary battery that can be repeatedly used for charging and discharging for a long period of time can be provided.

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing a state where the safety valve is ruptured, and FIGS. 3 and 4 are sectional views showing other embodiments.

(1)...Outer can (5)...Negative electrode material (6)...Cathode material (13)...Void part

[Brief explanation of the drawing]

Figure 3 Figure 4

Claims (1)

[Claims] A negative electrode made of a fired organic material and Li_xMO_2(M
represents at least one type of Co or Ni, 0.05≦x
≦1.10. ) and an electrolytic solution are housed in a container.
．． A non-aqueous electrolyte secondary battery characterized by having a void of 3 cc or more.