JPS61216243A - Cell - Google Patents

Abstract

PURPOSE:To obtain a very high energy density per unit mass of the positive electrode of a cell, and a high discharge voltage, and to keep it at a high constant value for a long time, by making the positive electrode with a composite of carbonaceous materials adhere and deposit onto a porous electro-conductive carrier. CONSTITUTION:In an organic electrolyte cell consisting of a negative electrode composed of active material of light metals a separator impregnated with organic solvent solution of light metal salts and a positive electrode, the positive electrode is made with a composite of carbonaceous materials adhered and deposited on a porous electro- conductive carrier. There is no special restriction as to the carbonaceous materials to be used, and they are not necessarily pure, and so a carbonaceous material of which carbon content is higher than 90wt% and electro-conductivity is less than 10<6>OMEGAcm is practically used. By making the positive electrode with a composite of carbonaceous materials adhered and deposited on a porous electro-conductive carrier, a very high energy density per unit weight of the positive electrode and a high discharge voltage can be obtained, the high discharge voltage can be kept constant for a long time, and there is no problem concerning public nuisance and recovery of resource, and furthermore it is inexpensive.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a so-called organic electrolyte battery.

More specifically, the present invention relates to an organic electrolyte battery having excellent properties, in which a composite material in which a light metal is used as a negative electrode active material and a carbon-based material is attached and supported on a conductive porous material is used as a positive electrode.

[Conventional technology]

2. Description of the Related Art Recently, the development of electronics as seen in LSI or ultra-LSI has been remarkable, and efforts are being made to make various electronic devices lighter, thinner, and smaller. As a result, the demand for batteries as a power source, especially for cordless devices, is increasing, and it is desirable to develop batteries with higher voltage, higher energy density, and higher reliability. It is being done.

BACKGROUND ART Conventionally, various types of lithium batteries using lithium as a negative electrode active material are known as high voltage and high energy density batteries. Typical lithium batteries include those using manganese dioxide (MnO2) or graphite fluoride as the positive electrode active material, and these are already commercially available.

However, although manganese dioxide-lithium batteries can obtain high voltage, the battery voltage rapidly decreases as it discharges, and when used for a long period of time, it is difficult to use batteries such as electronic watches, calculators, or microcomputers that are currently widely used. When used for memory backup, it has been pointed out that the operating voltage tends to run out during use, resulting in low reliability.In addition, there are concerns about the disposal of manganese dioxide-lithium batteries, pollution and resource recovery, etc. There are concerns about this issue.

On the other hand, fluorinated graphite-lithium batteries are manganese dioxide-lithium batteries.
Although the flatness of maintaining a constant discharge voltage has been improved compared to lithium batteries, it is insufficient, and it also has drawbacks such as a low discharge voltage and poor discharge characteristics under high loads. Both manganese dioxide and Graphite Co., Ltd. have low electrical conductivity, and in order to increase the electrical conductivity, a conductive additive is added, making the positive electrode material heavier, which results in a decrease in the energy density per unit weight on the positive electrode side. There is. In addition, when using manganese dioxide, a chemical treatment process is required in advance, and when using fluorinated graphite, a process of fluorinating graphite etc. is required, so both are expensive materials. There is.

[Problem that the invention seeks to solve]

The present invention focuses on the problems of each of the conventional lithium batteries, and aims to provide a positive electrode with a very high energy density per unit weight, a high discharge voltage, and a high constant discharge voltage that cannot be maintained for a long period of time. be.

[Means to solve the problem]

The inventors of the present invention have conducted various studies to solve the various drawbacks of organic electrolyte batteries, such as conventional lithium batteries, and have surprisingly found that light metals are used as negative electrode active materials, and carbon-based materials are used as negative electrode active materials. We have discovered that when a positive electrode is a composite supported on a conductive porous material, a lithium battery can be obtained which has extremely high energy density, excellent battery properties, and is inexpensive and easy, and has developed the present invention. It was completed.

That is, the present invention provides an organic electrolyte battery using a negative electrode containing a light metal as an active material, a separator impregnated with an organic solvent solution of a light metal salt, and a positive electrode, in which the positive electrode has a carbon-based material attached and supported on a conductive porous body. This battery is characterized by being a composite.

There are no particular restrictions on the carbon-based material used in the present invention, and it does not need to be a pure product.
A carbon-based material is used that has an electrical conductivity of 100 Ω or less, preferably 10 to 10 Ω, and has an electrical conductivity of 100 Ω or less, preferably 95 wt 4 or more.

Representative examples of carbon-based materials include carbon black and activated carbon. Practically speaking, the former is preferred.

The carbon black used in the present invention is commonly available, and there are no restrictions on its raw materials or manufacturing method, but typical practical examples include Ketjen black, acetylene black, furnace black, thermal black, lamp black, and Channel black etc. can be mentioned. Among these, preferred carbon blacks include Ketjen black, acetylene black, and furnace black. Among these, Kettin black is preferable because it has excellent battery characteristics, although it is relatively expensive.On the other hand, acetylene black and furnace black are also preferable because they are relatively inexpensive, although the battery characteristics are comparable to conventional products. . These carbon blacks can be used alone or in combination of two or more. These carbon blacks can be used in the form of powder, granules, or lumps, but among these, powders and granules are preferably used. In addition, carbon black includes a primary aggregate formed by aggregation of spherical carbon black particles to form a chain structure, a secondary aggregate formed by aggregation of these -order aggregates, and a secondary aggregate formed by this secondary aggregate. Higher-order aggregates such as tertiary aggregates formed by further aggregation (second-order aggregates and subsequent aggregates, hereinafter the same) can be used. Among these, -order aggregates are preferred. It is preferable that the Mogo higher-order aggregate is deaggregated by, for example, ultrasonic treatment and used as a primary aggregate.

The ultrasonic treatment is carried out by irradiating a suspension of high-order aggregates of carbon black in a dispersion medium such as an organic solvent with ultrasonic waves in a conventional manner.

The organic solvent at this time is not particularly limited, but examples include aliphatic hydrocarbons, aromatic hydrocarbons, halides,
Examples include esters, ketones, lactones, alcohols, etc., but organic solvents with low boiling points are preferably used.

The conditions for ultrasonication are not particularly limited as long as the carbon black can maintain its primary aggregate as soon as the chain structure peculiar to its Kao aggregates is destroyed. Although it cannot be specified unconditionally as it varies depending on the type, it is usually, for example, 20°,000 cycles or more, preferably rjz, oo.

Carbon black treated with ultrasonic waves for about 28,000 cycles until the chain structure is destroyed has a lower electrical conductivity than the primary aggregate. Note that the presence or absence of a chain structure of carbon black can be confirmed using an optical microscope or an electron microscope.

Further, the properties of these carbon blacks are improved, if necessary, by physical treatment such as heating and washing, or chemical treatment with acid, alkali, etc., before use.

You can also use

There is no particular restriction on the size of carbon black, but for practical purposes, the average particle size is about 10 to 5 oooX, preferably 2
00 to 2000X, or a specific surface area (same as 1 or less by nitrogen adsorption method) of about 5 to 2000 m'/g, preferably 50 to 15 oom/g.

Furthermore, there are no particular limitations on the activated carbon used in the present invention;
9 or more, preferably specific surface area 500 to 4000 rIt/
9 size activated carbon is used. The activated carbon may be selected from powder, granules, or crushed forms, with powder forms being preferred.

In addition to carbon black and activated carbon, charcoal, coal, graphite, and coke can also be used as carbon-based materials.

In addition, the conductive porous body used in the present invention may be a plate-shaped material made of a conductive material such as metal fiber, metal-plated fiber, carbon fiber, carbon composite fiber, metal-deposited fiber, or metal-containing synthetic fiber. It is a porous body. The form of the porous body is a practical soil, usually, for example, a net, a woven or non-woven fabric, and paper, but is not necessarily limited thereto.

The metal that is the material of the conductive porous body is usually platinum,
Gold, titanium, nickel and stainless steel are preferably used. The conductive porous body is preferably lightweight and highly conductive. For example, a porous body made of carbon fiber is preferred because it is lightweight and highly conductive. Further, the pore diameter of the conductive porous body of the present invention must be larger than the size of the carbon-based material.

The weight of the conductive porous body is 1/10 to 10 times, preferably 115 to 5 times, the weight of the carbon-based material used.

Furthermore, the thickness of the conductive porous body varies depending on the material, desired battery capacity, battery area, etc., and cannot be unconditionally specified; .

Particularly preferably, it is about 0.1 to 5111.

The composite according to the present invention is a material in which a carbon-based material is attached and supported on a conductive porous body, and a method known per se can be used as a method for adhering and supporting the carbon-based substance on a conductive porous body. That is, for example, 0) a method in which a suspension of a carbon-based material dispersed in an organic solvent is uniformly poured into one side of a conductive porous material while being sucked, and then dried; Q
(2) A method of supporting a carbon-based material on a conductive porous material as it is in a dry state or using an adhesive; There are methods of polymerizing -, among which methods (a) and (b) are preferred for practical purposes, but the method is not limited to these methods.

In the present invention, members other than the positive electrode, such as the light metal as the negative electrode active material, the organic solvent solution of the light metal salt, and the separator, are the same as those in conventional organic electrolyte batteries.

That is, the light metal that is the negative electrode active material is not particularly limited, but for example, lithium, sodium, potassium, magnesium, barium, and aluminum are preferably used, and among them, lithium is most preferred. The light metal that is the negative electrode active material may be in the form of a plate, and in practice, light metal foil, light metal plate, light metal fiber mesh, etc. are usually used, and the thickness thereof is usually about 1 to 5000 μm, preferably 20 μm. ~2000 μm.

Although there are no particular restrictions on light metal salts, representative examples include LiCl, LiCl0a, LiBF4, LiPF5,
LiAsFa, Li5bFs, NaCX, NaBF4,
Na PF a, Na S bF a, KCl0a, K
BF4, KPF6, KSbFa, Mg((JOn)2,
and LIAIC14. Among these, lithium metal salts are preferred. These metal salts are usually used alone, but any organic solvent that can be used in combination of two or more types may be used, but aprotic and high dielectric constant organic solvents are preferable. Examples include propylene carbonate, r-butyrolactone, dimethylformamide, dimethyl sulfoxide, acetonitrile, ethylene carbonate, tetrahydrofuran, dimethoxyethane, methyl formate, and dichloroethane. These organic solvents may be used alone or as a mixed solvent of two or more. Depending on the type of battery used or the type of electrode used, impurities such as oxygen, water, or protic solvents in these organic solvents may deteriorate the battery characteristics. In the case where such organic solvents are used, it is preferable to purify these organic solvents in advance by a conventional method. In addition, the concentration of the light metal salt in the solution is practically 0°1 to 1.5 mol/
It is said to be about 1.

As the separator, nonwoven fabrics and woven fabrics made of synthetic resin fibers, nonwoven fabrics and woven fabrics made of glass fibers, nonwoven fabrics and woven fabrics made of natural fibers, and the like are used. Examples of this synthetic resin include polyethylene, polypropylene, and polytetrafluoroethylene. Although the thickness of the separator cannot be determined unconditionally, it is capable of containing and retaining the required amount of electrolyte (organic solvent solution of light metal salt).
The thickness may be as long as it is necessary to prevent a short circuit between the positive electrode and the negative electrode, and for practical purposes, it is usually 0.05 to 10 mm%, preferably 0.
．． It is said to be about 1 to 2xm.

In the battery of the present invention, it is possible and preferable to use a current collector as in conventional coin-type batteries. As the current collector, a current collector used in conventional coin-type batteries can be used. That is, an electrochemically inactive conductor is used for each of the electrolytic solution and the positive and negative electrode active materials. For example, metal plates, foils and meshes such as platinum, gold, palladium, nickel and stainless #1, glass and plastic plates with oxide coatings such as indium oxide and tin oxide, activated carbon, graphite, acetylene black and carbon fiber, etc. The carbons can be used in a variety of forms, such as plates, nets, woven and non-woven fabrics, etc. The positive and negative image current collectors may be made of different materials or may be made of the same material.

Further, the thickness thereof is O', about 001 to 101111, preferably 0.01 to 511.

The structure of the 1,000 cell of the present invention is similar to that of a conventional organic electrolyte cell, and the basic structure of an example thereof is shown in FIG. That is, FIG. 1 is a cross-sectional view showing the basic structure of an example of a coin-type battery according to the present invention, in which a negative electrode current collector 2 is crimped onto one surface of a negative electrode active material 1. In addition, a separator 6, a positive electrode 4, and a positive electrode current collector 5 are sequentially pressure-bonded to the other surface of the negative electrode active material 1. Thus, the negative electrode current collector 2 and the positive electrode current collector 5 are connected to the lead wires 6 and 61, respectively.

Note that this coin-type battery was housed in a container made of Teflon (trade name), and its characteristics were measured.

〔Example〕

The present invention will be explained in more detail with reference to the following examples.

Example 1 In FIG. 1, the negative electrode active material 1 is a lithium metal thin plate (thickness 0.05crIt, diameter 2.6cIn), and the negative electrode current collector 2 is a stainless steel thin plate (thickness 0.1cm, diameter 2.6α). )
, the separator 3 is made of glass fiber nonwoven fabric (thickness 0.02
(m, diameter 2.6crIl), a mixed solvent of distilled and dehydrated propylene carbonate and ethylene carbonate (
This is a product impregnated with a lithium perchlorate solution (concentration of lithium perchlorate: 1 mol/11') dissolved in a volume ratio of 1:4. The positive electrode 4 is Ketjenblack (average particle size 5 [10A) 10.51!9 manufactured by Nippon EC ■] and benzene 5
The suspension dispersed in WLt was coated with conductive porous material Creca Paper E-704, thickness 0.03cIrL1 diameter 2.6c.
The composite and the positive electrode current collector 5 are made of coin-shaped lithium, which is the same stainless steel thin plate as the negative electrode assembly 2. Got the battery.

The initial open circuit voltage of the lithium battery thus produced was 3.08V. When a constant load discharge of Ω was carried out in 4.7, the relationship between energy density and discharge voltage was as shown by the curve ω in Fig. 2. At this time, the average open circuit voltage until the discharge voltage drops to 2.0■ is 2.59V, per positive electrode (the sum of Ketjenblack, which is a carbon-based material, and carbon fiber, which is a conductive porous material - the same applies hereafter) IKf. The discharge capacity of is 4
05.3Ah fake, energy density is IO44.5Wh
/Kf.

Curve (b) in FIG. 2 shows the relationship between energy density and discharge voltage for a commercially available fluorinated graphite-lithium battery, and curve (C) for a commercially available manganese dioxide-lithium battery.

From these results, it can be seen that the positive electrode battery of the present invention clearly has an energy density per unit weight of the positive electrode that is approximately twice that of a commercially available product, and also has excellent discharge voltage flatness.

Comparative Example 1 A battery was produced in the same manner as in Example 1 except that only Ketjenblack 10M9 was used as the positive electrode 4. The initial open circuit voltage of this battery is 2,92V.

In 4.7, the discharge voltage during constant load discharge of Ω is 2, Ov.
The average open circuit voltage until it drops to 2°36v1 positive electrode 1K
The discharge capacity per gram was 19.8 Ah/Kg, and the energy density was 46.7 wh.

Comparative Example 2 A lithium battery was produced in the same manner as in Example 1, except that only the carbon fiber molded product (trade name: Kureriki Paper E-704) 18~ was used as the positive electrode 4.
-17- Manufactured. The initial open circuit voltage of this lithium battery is 2°62V, 4.7Ω
The discharge voltage during constant load discharge is 2. The average open circuit voltage until it drops to Ov is 2.15V, the discharge capacity of the positive electrode IKf is 3, OAh/Kl, and the energy density is 6.5.
It was wh^.

Example 2 Example 1 except that the positive electrode 4 was a composite made of 10 mm of acetylene black (average particle size 420 A) manufactured by Electrochemical ■ and 18 mm of carbon fiber molded product (trade name: KUREKA PAPER E-704). A lithium battery was produced in the same manner as above.

The initial open circuit voltage of this lithium battery is 2.89V, 4.7
The discharge voltage during constant load discharge of Ω is 2. The average open circuit voltage until it drops to OV is 2.24V.

The discharge capacity of the positive electrode IKf was 121.4 Ah^, and the energy density was 271.9 Wh/Kf.

Comparative Example 3 Example 1 except that only acetylene black (average particle size 420A) 101119 manufactured by Denki Kagaku ■ was used as the positive electrode 4.
A lithium battery was produced in the same manner as above. The initial open circuit voltage of this lithium battery is 2°90V, and the discharge voltage during constant load discharge of 4.7Ω is 2.90V. The average open circuit voltage until it drops to Ov is 2.32V, the discharge capacity per 1Kf of positive electrode is 12.6Ah/Energy density is 29.2Wh/
It was the first time.

Example 3 The positive electrode 4 was Asahi Carbon Furnace Black H3-50.
A lithium battery was produced in the same manner as in Example 1, except that a composite was made from 10119 (average particle diameter: 760 A) and 18 cm of a carbon fiber molded product (trade name: Kureriki Paper E-704). The initial open circuit voltage of this lithium battery is 2°92V, and the discharge voltage during constant load discharge of 4.7Ω is 2.92V. The average open circuit voltage until it drops to Ov is 2.3
8V, discharge capacity per 1Kf of positive electrode is 277.9Ah/
The energy density of the beast was 662°5w/Kf.

Example 4 As a conductive porous body for the positive electrode 4, a carbon fiber molded product manufactured by Toshi
Product name: Trading card mat, thickness 0.02cIIL1 diameter 2
．． A lithium battery was produced in the same manner as in Example 1 except that 6Cm) 16109 was used.

The initial open circuit voltage of this lithium battery is 3.08V.

In 4.7, the discharge voltage during constant load discharge of Ω is 2, Ov.
The average open circuit voltage until it drops to 2゜s 8 V, positive electrode I KghftA) no discharge capacity *2 B 8. 9Ah
/Kg, and the energy density was 745.4 wh/odor.

Example 5 It was confirmed that the positive electrode 4 had a chain structure using a Ketjen Black 8.5 microscope (manufactured by Nippon EC) with a specific surface area of 967.5 m'/g), and then it was examined using a Kureha test. Chemically manufactured carbon fiber molded product (product name: KUREKA PAPER E-704
, thickness 0゜03cIn, diameter 2.6cIIL1118■
) Pour it evenly while suctioning from one side of the
A lithium battery was produced in the same manner as in Example 1, except that the composite was obtained by drying under reduced pressure.

The initial open circuit voltage of the lithium battery produced in this way was 5.08V, and when a constant load discharge of 4.7Ω was performed,
The relationship between energy density and discharge voltage is shown by the curve (d
) became like this. At this time, the discharge voltage is 2. The average open circuit voltage until it decreased to Ov was 2.62V, the discharge capacity per IKg of positive electrode was 534.5Ah/Kg, and the energy density was 1's99.4WkV'l14.

Examples 6 to 8 Lithium batteries were prepared in the same manner as in Example 5, except that the ultrasonic treatment time of Ketjen black was changed to the time shown in Table 1, and a discharge experiment was conducted.

The results are shown in Table 1.

Table 1 ☆ Discharge voltage is 2. Value until it decreases to Ov ☆☆ Value per positive electrode 1 Example 9 Positive electrode 4 was made of activated carbon powder with a specific surface area of 1,400 dl
A suspension of 18,5119 dispersed in benzene sml was made into a carbon fiber molded product (trade name: trading card mat, thickness 0.02 CIll, diameter 2°6 crn 1 weight 16 cm).
A lithium battery was produced in the same manner as in Example 1, except that the composite was formed by pouring the mixture into a uniform layer while suctioning from one side of the mixture and drying under reduced pressure.

The initial open circuit voltage of the lithium battery thus produced was 3.18V. Subsequently, when a constant load discharge of Ω was performed at 4°7, the relationship between energy density and discharge voltage became as shown by curve (e) in FIG. 4. At this time, the discharge voltage is 2. The average open circuit voltage until it drops to OOV is 2. S
IV.

Discharge capacity per positive electrode,,! 249.1 Ah/odor,
The energy density was 650.6 wh/4.

Comparative Example 4 A battery was prepared in the same manner as in Example 9, except that only activated carbon powder with a specific surface of #1,4oom/, Sj, 18.5cm was used as the positive electrode 4. The initial open circuit voltage of this battery is 3. OO
The discharge voltage during constant load discharge of V, 4.7KO is 2.
The average open circuit voltage until it drops to OV is 2.55V, the discharge capacity per 1kg of positive electrode is 66.5All/, and the 9% energy density is 95. Owh/'Kg. The relationship between energy density and discharge voltage is shown by curve (f) in FIG.

Comparative Example 5 A lithium battery was produced in the same manner as in Example 1, except that only a carbon fiber molded product manufactured by Toshishi (trade name: Trading Mat, thickness o, o2cIIL1 weight 16cm) was used as the positive electrode 4. The initial open circuit voltage of this lithium battery is 2,82V14,
7, the discharge voltage during constant load discharge of Ω is 2. The average open circuit voltage until it decreased to Ov was 2.41 V, the discharge capacity per kg of positive electrode was 1.2 Ah, and the energy density was 2.9 wh/Kg.

〔Effect of the invention〕

The battery of the present invention has an extremely high energy density per unit weight of the positive electrode, a high discharge voltage, and
In addition, it has excellent battery characteristics in that it can maintain a high discharge voltage for a long period of time, has no problems with pollution or resource recovery, and is inexpensive.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the basic structure of an example of the battery of the present invention, and FIGS. 2 to 4 are graphs showing battery characteristics. In FIG. 1, 1... Negative electrode active material 2... Negative electrode current collector 3... Separator 4... Positive electrode 5... Positive electrode current collector 6.6
1... Lead wire patent applicant Kazuyoshi Nagano, representative of Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] In an organic electrolyte battery using a negative electrode containing a light metal as an active material, a separator impregnated with an organic solvent solution of a light metal salt, and a positive electrode, the positive electrode is a composite in which a carbon-based material is attached and supported on a conductive porous body. Characteristic batteries.