JPS62188167A - Lithium battery - Google Patents

Abstract

PURPOSE:To increase open circuit voltage, discharge voltage, and energy density by containing acetylene black having specified physical properties in a positive active material in a lithium battery. CONSTITUTION:A negative active material is made of lithium or lithium- aluminum alloy. A positive active material is made of an inorganic material except for carbon fluoride. An electrolyte solution is made of a nonaqueous solution. Acetylene black having a primary particle size of 25nm or less, a relative surface area of 500m<2>/g or more, and metallic impurities of 500ppm or less is contained in the positive active material of this lithium battery. Thereby, open circuit voltage, discharge voltage, and energy density are increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to improvement of lithium batteries, and is applicable to calculators, watches, cameras, pacemakers for memory retention, tape recorders, radios, hearing aids, lights, smoke detectors, paging, etc. It is expected that it will be used.

[Conventional technology]

Conventionally, the negative electrode active material is metallic lithium or HIJ lithium-aluminum alloy, the positive electrode active material is carbon fluoride, manganese dioxide, sulfur dioxide, thionyl oxide, silver chromate, etc., and the electrolyte is anhydrous propylene carbonate or r-butyrolactone. Lithium batteries made of , dimethyl sulfoxide, acetonitrile, dimethyl formamide, etc. have been put into practical use. Furthermore, in order to develop a new type of battery, the positive electrode active materials include fluorine, oxygen, sulfur, chlorine, cupric fluoride, nickel fluoride, cupric oxide, cupric chloride, molybdenum oxide, nickel chloride, and fluoride. Lithium batteries using cadmium oxide, nickel sulfide, etc. have been proposed (``Battery Handbook'' published by Denki Shoin).

[Problem that the invention seeks to solve]

Improving the performance of a battery mainly depends on improving energy density and discharging potential, and the present invention aims to provide a lithium battery with even higher performance.

As a result of extensive studies to achieve this object, the present inventors discovered that acetylene black having specific physical properties could be further included in the positive electrode active material, and completed the present invention.

[Means for solving problems]

That is, the present invention provides a lithium battery in which the negative electrode active material is metallic lithium or a lithium-aluminum alloy, the positive electrode active material is an inorganic material other than carbon fluoride, and the electrolyte is a non-aqueous electrolyte. , primary particle size 25mm
Below, specific surface area 500f/9 or more, metal impurity 50
This is a lithium battery characterized by further containing acetylene black of 0 ppm or less.

The present invention will be explained in more detail below.

First, to explain the material used in the present invention, the negative electrode active material is metallic lithium or a lithium-aluminum alloy. As the positive electrode active material, inorganic substances other than carbon fluoride, such as manganese dioxide, sulfur dioxide, thionyl oxide, silver chromate, fluorine, oxygen, sulfur, chlorine, cupric fluoride, nickel fluoride, and ferric oxide are used. It is a mixture or molded product of copper, cupric chloride, molybdenum oxide, nickel chloride, cadmium fluoride, nickel sulfide, etc., and acetylene black having the following physical properties. Among these, the most preferred combination is manganese dioxide, especially electrolytic manganese dioxide, and acetylene black. As a non-aqueous electrolyte,
Anhydrous propylene carbonate, γ-butyrolactone,
A single or mixed solution of dimethyl sulfoxide, acetonitrile, dimethylformamide, etc., if desired.
A Lewis acid such as PF, NaPF6, LiAsF6, etc. is added.

The acetylene black contained in the positive electrode active material according to the present invention has a primary particle size of 25 mm or less and a specific surface area of 500 m''/J.
The above is a book with physical properties (metal impurities of 500 ppm or less). The reason for using such acetylene black is as follows. That is, the primary particle size is 25 mm.
When the temperature exceeds 100%, the number of acetylene blacks adhering to the surface of inorganic substances other than carbon fluoride decreases, impeding electron conduction.

If the specific surface area is smaller than 500 m'/.9, the apparent reaction area of the positive electrode active material decreases, so the higher the current density discharge, the more likely polarization will occur and the overvoltage will increase. Furthermore, if the metal impurities exceed 500 ppm, the inorganic substances other than carbon fluoride and the metal impurities form a local battery, and the rate of inhibiting the elementary reaction between lithium and the inorganic substances other than carbon fluoride becomes high. Battery life will be shortened. Note that the metal impurities are h%Nl, Cu.

Ca, 8t% M and V are elements that particularly inhibit the electrochemical reaction between the negative electrode and the positive electrode active material.

An example of a method for manufacturing a lithium battery will be shown below.

The shape may be any shape such as a cylindrical shape or a coin shape.

Cylindrical lithium batteries are made by mixing an inorganic substance other than fluorocarbon with a binder such as fluororesin, polyethylene, or other resin and acetylene black, and pressing the mixture with a roll on a metal grid to form a ribbon-shaped positive electrode. is molded and wrapped with a polypropylene nonwoven separator. The negative electrode uses a lithium metal ribbon or a lithium-aluminum alloy ribbon formed by pressing on a metal grid. The positive and negative electrodes are stacked and rolled into a loop shape, inserted into a battery case, filled with a non-aqueous electrolyte, and sealed. Insulating plates are placed on the top and bottom for insulation, a sealing plate is set as the positive terminal, and the battery case is used as the negative terminal.

Coin-plated lithium batteries contain inorganic materials other than carbon fluoride.
A binder, a resin such as a fluororesin or polyethylene, and acetylene black are added and mixed with the binder L7, and a mixture is formed by pressure molding and used as a positive electrode. A sheet of lithium is punched out and used as the negative electrode. A separator and, if necessary, a liquid-absorbing material adsorbed with a non-aqueous electrolyte are sandwiched between the positive and negative electrodes, the electrodes are insulated with a gasket, and the battery is inserted into a case. As the separator, glass filter paper, asbestos filter paper, etc. are generally used.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

The acetylene gas pyrolysis furnace used in the production of acetylene black is a vertical type with a total length of 2.4 mm.
m, inner diameter Q, 4 m s drain diameter 0.25 m.

The inner wall from the top of the furnace to 0.3n+ is constituted by a water cooling jacket, and the other inner walls are constructed of refractory bricks. In order to maintain the temperature of the pyrolysis furnace at 800° C. or higher, 1 ONtt//H of carbon oxide and 60 Nd/H of air are supplied for combustion. With this pyrolysis furnace, oxygen gas and 40Kt/c
A mixed gas of water vapor (temperature: 150°C) saturated with water was supplied, and acetylene gas was also supplied from the outer annular part of the double pipe nozzle to cause the acetylene gas, oxygen, and water vapor to react, and then the mixture was produced according to a conventional method. Acetylene black was collected by cooling. The conditions for acetylene gas, oxygen gas, and water vapor are as follows: type A (7) of the present invention;
8Nm'/I(.

Oxygen gas 98FF//H, water vapor 4.5 Nn? /H, type B, acetylene gas 20N+?
//H oxygen gas 9 Nnl/H, water vapor 4.5 Nnl/H.

The properties of the obtained acetylene black are that the primary particle size is 11~
The diameter was 13 mm, and the specific surface area was 300 to 350 dll.

This acetylene black was continuously filled into a horizontal reactor made of quartz, and partially oxidized by supplying air at a rate of 21 t/h at a temperature of 570°C. Its physical properties are shown in Table 1.

As comparative examples, commercially available acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Denka Block") and by-product carbon black (manufactured by Nippon EC Co., Ltd., trade name "Ketjen ECJ") were used.
) was used.

Table 1 Performance of Lithium Battery The performance of the lithium battery was measured using the experimental apparatus shown in the drawing. 1 is an outer tank, and a dry box in which the atmosphere was replaced with argon was used. 2 is a glass cell that houses an electrolytic solution and both electrodes.

Lithium perchlorate (Aldrich II, purity 99.
9%) was dried at 190°C for 24 hours, dissolved in anhydrous propylene carbonate (Hasui Kagaku Shushushu), special grade reagent) K, a 1 mol/L solution was prepared, and the mixture was added to a flask with 4A molecular sheep again. sealed inside.

This solution was subjected to Karl Fischer titration to obtain a water content of 100.
After confirming that it was below ppm, it was used as a non-aqueous electrolyte. 3 is a negative electrode, which is a piece of lithium metal foil sandwiched between nickel meshes and fixed in an inert gas. 4 is a positive electrode, which is made of electrolytic manganese dioxide (
Mitsui Kinzoku C Co., Ltd.)lliEMD purity 92.52) 24
10Iq of vacuum-dried material was collected at 200°C for an hour, and 10Iq of polyethylene powder, which had been vacuum-dried in advance, was mixed as a binder with 10# of various acetylene blacks (carbon blacks). O
Approximately 200~/- by sandwiching between vtxx filter paper and tablet molding machine
The pellets were compression molded at a pressure of . Carbon fiber was wrapped around this pellet and one end was used as a terminal.

5Fi voltage follower, 6! ri voltage recorder, and 7 used a potentiostat or galvanostat as a constant current device.

The battery was sealed in a desiccator with silica gel in a dry box in which the atmosphere was completely replaced with argon, and the discharge was carried out at 25°C.
The test was carried out at a constant temperature of .

First, after the battery was constructed, the discharge circuit was left open for 24 hours. After leaving it for 24 hours, it was discharged at a constant current of 0.1 mA I-'', and the point when it dropped to 1.5 V was considered the end of the discharge, and the open circuit voltage, utilization rate, and energy density were calculated.The results are shown in the table. Shown in 2.

Table 2 Next, a similar test was conducted using cupric fluoride, cupric chloride, and nickel chloride instead of manganese dioxide in the above example. The results are shown in Table 3.

〔Effect of the invention〕

According to the lithium battery of the present invention, a very high open circuit voltage,
The radiation t'flL position and energy density can be obtained.

[Brief explanation of drawings]

The drawing is an explanatory diagram of a lithium battery used in Examples. 1... Outer tank, 2... Glass cell, 3... Negative electrode, 4... Positive electrode, 5
... Voltage follower, 6... Voltage recorder, T
... Constant current device.

Claims (1)

[Claims] 1. In a lithium battery in which the negative electrode active material is metallic lithium or a lithium-aluminum alloy, the positive electrode active material is an inorganic material other than carbon fluoride, and the electrolyte is a non-aqueous electrolyte, the positive electrode active material contains primary particles. Diameter 25mm or less, specific surface area 5
A lithium battery further comprising acetylene black having a concentration of 00 m^2/g or more and a metal impurity of 500 ppm or less.