JPS6025165A - Battery - Google Patents

Abstract

PURPOSE:To improve the current efficiency and the energy efficiency of a battery by coating a conductive macromolecular substance on the entire surface of a porous thin molded body consisting of powder or the like of a compound having a high conductivity and a large effective surface area. CONSTITUTION:Powder or fiber of a member such as amorphous carbon black is molded into a sheet-like porous thin body having a high conductivity and a large effective surface area. The thus obtained porous member is used as a base body and a conductive macromolecular substance such as polyacetylene or polypyrrole is either stuck to the surface of the base body or packed into the base body, thereby making an electrode. After that, a battery is assembled by using a metal such as lithium or sodium as a counter electrode. The thus obtained battery has high coulomb efficiency and energy efficiency, decreased seld discharge and an increased cycle life. Therefore disadvantages which may be caused when a porous filmlike polyacetyle is used as an electrode can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a battery having high current efficiency and energy efficiency, low self-discharge, and long cycle life.

Recently, it has been reported in JP-A-56-13646 that it is possible to manufacture rechargeable batteries with high energy density by using porous film-like polyacetylene as electrodes.
It is known from Publication No. 9.

However, this battery had the drawbacks of large self-discharge and short cycle life. That is, if
, after 10 to 20 hours of subsequent release 1a have elapsed, the remaining tolerance decreases to the initial level of 40 to 50 chi. Furthermore, the cycle life when charged with a charge equivalent to 6% doping was about 40 times, and the battery could not be put to practical use as it was. Although it is not possible to solve these problems, regarding cycle life, it is important to note that irreversible reactions other than doping reactions occur simultaneously at a certain rate during the charging process.
It is estimated that this accelerates the deterioration of the acetylene film. In addition, self-discharge is a dedoping reaction that progresses in an open circuit state, but this is not unrelated to the deterioration of polyacetylene, and this phenomenon occurs even in films that can still be sufficiently charged and discharged for m cycles. This is because it occurs.

In view of the current situation, the present inventor has conducted intensive research on improving the characteristics of batteries using conductive polymer materials as described above, and as a result, has improved current efficiency and energy efficiency, suppressed self-discharge, and We have developed a battery that exhibits a number of excellent performances such as extending the lifespan.The entire surface of the porous thin molded body is made of powder or fiber of a material that has high conductivity and a large effective surface area. It is characterized by the use of an electrode with a polymer substance interposed therein.

The porous thin molded body used as the substrate of the electrode in the present invention needs to have high electrical conductivity and a large effective surface area, and the electrical conductivity is preferably 10 G (0 cm) or more. Also, the effective surface area is 100 m2/
g or more is desirable, especially 1000 to 2000 m2
7g is preferred. For example, powder made of amorphous carbon black or Grapheye F, fibers, or carbon black or graphite obtained by gas phase reaction is molded into the shape of a sheet, woven fabric, nonwoven fabric, felt, etc. by known means. . Particularly preferred are polymeric fibers such as polyacrylonitrile, cellulose fibers, and activated carbon fibers made from petroleum pitch in the form of felt or paper sheets.

In the present invention, examples of the conductive polymer substance interposed on the surface or inside of the porous molded body include 45-lyacetylene, polygirol, polyparaphenylene, polyporous phenylene sulfide, and polyphenylene sulfide. Acrylonitrile, etc., may be applied in the form of a film to the surface of the porous IT molded body, or may be contained in powder form within the porous molded body.

Among these, polyacetylene is particularly preferred, and is produced in film form, powder form, 1d J, and polyScl strain pH. 1.Although there is no particular limitation on the ratio of the porous thin molded body to the conductive polymer material, the latter is usually 10% to 50%, preferably about 30%.

The electrode used as a counter electrode in the present invention includes metals such as lithium and sodium, but is not necessarily limited to these. It is also possible to use electrodes in which the above-mentioned conductive polymer substance is interposed for both electrodes.

Next, examples of the present invention will be described.

Example (1) A. Production of electrode A 200 m, l glass reaction vessel with an effective surface area of 16
Felt-like activated carbon fiber (width 6 an x length 15
Cm×thickness: 3 mm, weight: approximately 3 g), and the air was sufficiently replaced with nitrogen gas. 20 ml of toluene, 3 mmol of tetracytoquine titanium, and 12 mmol of ethylaluminum were added to prepare a catalyst solution. After the reaction vessel was cooled to -78° C. and the nitrogen gas was evacuated, the activated carbon fibers were impregnated with the catalyst solution, and then purified acetylene gas at 1 atmosphere was introduced. This operation produces a film of polyacetylene on the surface of the activated carbon fiber,
Polyacetylene was also generated inside the fibers in a state of being entangled with the fibers. After 5 minutes, the ethylene gas was evacuated to completely stop the reaction. Next, after washing the fibrous and film-like polyacetylene six times with 40 ml of purified toluene,
Vacuum dried.

The activated carbon fiber thus obtained contained 0.6 g of po5- Liacetylene arrived f)1.

B. Battery test 1 cm" was exposed from the 7-giri acetylene-adhered activated carbon fiber prepared above, and the unadhered part of polyacetylene was peeled off, and this was used as a polyacetylene electrode (polyacetylene Jit6.6 Shoulder 2). Carbon fiber amount 8
．． As a counter electrode to this ¥M1 electrode, a 1 side 2 electrode was prepared in which metallic lithium was mechanically bonded to a nickel mesh.

A polypropylene nonwoven fabric, a polyacetylene electrode, and a platinum plate (lctn'') were sequentially placed on this lithium frame and mechanically adhered to it.
The sample was placed in a glass tube with a diameter of 1.5 cm filled with a 0 mol/a solution of propylene calf 1-nate, and lead wires were taken out from the nickel mesh and platinum plate, respectively, and the glass container was sealed.

Note that all of these operations were performed in an argon gas atmosphere.

The open circuit voltage of the battery thus obtained was approximately 3. Also, this battery is fixed at 1mA! ! The coulombic efficiency was measured by charging and discharging with a current of -C+-m1 and discharging ended when the voltage between the two electrodes reached 3. The results are shown in Table 1.

Note that the average voltage during discharge is 3.5V.

Also, charge at 0.3mA constant current for 60 minutes and discharge at 3V.
When a cycle test was conducted under the following conditions, there was no significant change in the uncharged potential or the shape of the charge/discharge curve until about 100 cycles, but from 110 cycles an increase in the uncharged potential and a decrease in the average voltage during discharge were observed. It was done. Also 1 m
After charging at a constant current of A for 60 minutes, the battery was left for a certain period of time and the remaining capacity was measured. The results are shown in Table 2.

Comparative Example A, Electrode Production A catalyst solution was prepared by placing 20 ml of toluene, 3 mmol of tetrabutoxytitanium, and 12 mmol of ethylaluminum into a 200 ml glass reaction vessel. Note that all of these operations were performed in a nitrogen atmosphere. Next, acetylene gas was introduced in the same manner as in Examples to synthesize a polyacetylene film on the glass wall of the reactor, and the reactor was evacuated after 5 minutes. The resulting film was then washed several times with purified toluene and then vacuum dried. The resulting thickness was approximately 0.
1 m of cis-type 7-rod rear 7-ethylene film and 1 crn
A comparative example was prepared using the same lithium electrode as in the example as the counter electrode for the battery test 4. did.

The weight of the polyacetylene film was approximately 4 m&, and the open circuit voltage was 2.5 V.

Coulombic efficiency and self-discharge tests were conducted on this battery in the same manner as in the examples. The results are listed in Tables 1 and 2, respectively.

In addition, when the battery was charged for 60 minutes at 0.3mA constant t'l', M+:, and the end of discharge was set at 2.5V, a cycle test was performed with Hill, and from around the 40th cycle, there was a sudden change in the uncharged potential. The battery began to rise and charging and discharging became impossible.

Table 1 Table 2 Table 9 - As is clear from the above table, the battery of the present invention has high coulombic efficiency, high energy efficiency, and self-emission. It has remarkable effects such as having fewer and longer cycle hemorrhoids in M6.

Applicant's agent: Patent attorney Suzue Takehiko Ifl-

Claims (1)

[Claims] A battery characterized in that an electrode is made of a porous thin molded body made of powder of a substance having high conductivity and a large effective surface area, and a conductive polymer substance is interposed on the entire surface of the porous thin molded body. .