JPS59154763A - Negative pole material for lithic secondary cell - Google Patents

Abstract

PURPOSE:To secure a negative pole material for a lithic secondary cell aiming at safety and improvements in the charging and discharging characteristics of a battery, by forming the negative pole material with lithium contained in a pyrolytic products of an allyl acetylene polymer. CONSTITUTION:An allyl acetylene copolymer expressed in a chemical formula (X is of H, a halogen group and a cyano group, A is of an alkyl group, an allyl group, etc., n is of 0-5, and m is of the number that molecular weight in a polymer becomes above 5,000) is made up in to a filmy form, a woven fablic form or the like. This copolymer is decomposed by heat whereby such a product as being porous and excellent in conductivity is secured. With this product set down to an electrode material, about 0.1-40g of lithium is contained in the pyrolytic product per 100g, and a negative pole material for a lithic secondary cell is formed up. Using this negative pole material, good reversibility in the charging and discharging cycles of the lithic secondary cell can be secured.

Description

[Detailed description of the invention] The present invention relates to a negative electrode material for lithium secondary batteries.

Recent advances in electronic technology, including LSI, have led to dramatic miniaturization and weight reduction of various devices, and the demand for lithium batteries with high energy density and high discharge voltage is increasing. . However, the lithium batteries that are in practical use are primary batteries, and the development of secondary batteries is attracting attention.

Transition metal oxides and sulfides are considered to be promising positive electrode active materials in secondary batteries, but since the negative electrode active material is lithium metal, problems such as densitolite occur during charging, making it difficult for secondary batteries to have stable performance. Not obtained.

do not have. In addition, methods have been proposed in which synthetic polymers such as polyacetylene and polyphenylene are used as negative electrode active materials.
It has problems such as being extremely difficult to synthesize, unstable in air, and difficult to handle.

The present inventors conducted extensive research with the aim of solving these problems, and as a result, they arrived at the present invention. That is, the present invention is a negative electrode material for a lithium secondary battery, which contains lithium in a thermal decomposition product of an arylacetylene polymer.

In the thermal decomposition product of the arylacetylene polymer in the present invention, the arylacetylene polymer has the general formula 6, where X is a H1 halokene group or a cyano group, A is an alkyl group, an aryl group, an alkoxy group, an aryloxy group, Nitro group, cyano group, amino group or halogen group, n
is an integer of 0 to 5 and τm is a number such that the molecular weight of the polymer is 5000 or more.

In general formula (1), the halogen group of X is “+
Br, l can be mentioned. The alkyl group in A is an alkyl group having a straight or side chain having 1 to 18 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group.

Examples include isopropyl group and butyl group. Examples of the aryl group in A include groups substituted with at least one group such as phenyl group and naphthyl group. Examples of the alkyl group include the alkoxy group in A mentioned above, and examples of the aryloxy group include the alkoxy group and aryloxy group from the alkyl group and aryl group in A mentioned above. Examples of the halogen group in A include CI, Br, and I. n is 0 to 5
, preferably an integer of 0 or 1. m is a number such that the molecular weight is 5000 or more, preferably 10,000~], O
The number is 00,000. When the molecular weight is less than 5,000, the strength as a film is insufficient.

Examples of monomers used to obtain the polymer represented by general formula (1) include the following monomers. These monomers may be used in combination.

[1] Phenyl acetylenes [2] Alkyl phenylacetylenes [3] Halochenophenyl acetylenes [4] Anophenyl acetylenes, etc. Among the W forms of [ra], the preferred one is phenylacetate. ', n-s, alkylphenylacetylenes and halokenphenylacetylenes, and particularly preferred are phenylacetylene, 2-methyphenylacetylene and 2-promo-1-phenylacetylene.

The polymer is Polymer Bu
lletin) 2, 823-827, 1980
Those obtained by the method described can be used. That is, the polymer can be obtained by polymerizing monomers using a catalyst obtained by irradiating a compound of a transition metal carbonyl from Group 1 of the periodic table with an organic halogen compound. For details of the above polymerization, please refer to Japanese Patent Application No. 55-181.
It is described in the specification of No. 090. The number average molecular weight of the obtained arylacetylene polymer is usually 5,000 or more, preferably 10,000 to 1,000,000, according to the percolation method.

In addition, its intrinsic viscosity is usually 01 to 10 de/g, preferably 03 to 5 de/g when measured in toluene at 30°C.
/9.

Furthermore, the electrical properties of arylacetylene polymers are usually IO"8 to 10 when evaluated by volume resistivity [25°C].
15 Ωcm, and the mechanical strength is usually 500 to 2000 kF/cm 2 when evaluated by tensile strength.

Although the form of the arylacetylene polymer is not particularly limited, the method for producing it into a powder, film, or sheet is usually a method of heating and heat-treating the polymer in an inert gas atmosphere.

The heating temperature is usually 100 to 1000°C, preferably 300°C.
~850°C, and the heating time is usually 1 to 50 hours, preferably 2 to 20 hours. Also, a method of heating and heat treatment in stages under an inert gas atmosphere, such as nitrogen gas.

For example, a method of heating and heat treating at 100 to 400°C for 05 to 10 hours and then heating and heat treating at 600 to 900°C for 1 to 10 hours can also be performed.

Arylacetylene polymers usually lose weight due to thermal decomposition. Although the weight loss varies depending on the type of arylacetylene polymer, for example, in the case of 2-chloro-1-phenylacetylene, it is usually 20 to 50% by weight, particularly 25 to 40% by weight based on the weight of the polymer.

The resulting thermal decomposition product of the arylacetylene polymer is usually a shiny black material. The shape of the pyrolysis product depends on the shape of the raw material arylacetylene polymer; for example, a film-like arylacetylene polymer yields a film-like pyrolysis product, while a fibrous arylacetylene polymer yields a fibrous pyrolysis product. pyrolysis products are obtained. It has this property and has excellent properties as an electrode material.

When incorporating lithium into the thermal decomposition product of the arylacetylene polymer, the amount of lithium in the thermal decomposition product is usually 1 to 40 g of O per 1002 of the thermal decomposition product, preferably 0.2 to 18 y.

A method for incorporating Iτ lithium, which is a thermal decomposition product of an arylacetylene polymer in the form of a film or a woven fabric, when incorporating lithium or rum into a thermal decomposition product of an arylacetylene polymer, and a method for incorporating lithium, a thermal decomposition product of an arylacetylene polymer in the form of a film or a woven fabric, and a method for incorporating lithium, a thermal decomposition product of an arylacetylene polymer in the form of a powder. Thermal decomposition products and powdered synthetic resins (Teflon, polyethylene, polystyrene, etc.) or petroleum or petroleum dry distillates such as pitch and tar are mixed, kneaded, and then heated and molded to contain lithium. can give.

Specific methods for containing include electrochemical methods, chemical methods, and physical methods.

In the electrochemical method, a thermal decomposition product of an arylacetylene polymer is used as a positive electrode, and a lithium foil is used as a negative electrode (lithium fluoride, lithium arsenic fluoride, lithium phosphorus fluoride, lithium chloride aluminate, lithium halide, etc.) as a propylene carbonate. , esters such as γ-butyrolactone,
Ethers such as dimethine ethane, dimethine-1-xyte-1-rahydrofuran, N-methyloxazolidinone, etc.
- Electrolyte obtained by dissolving N,N'-substituted imidazolidinone such as -substituted oxazolidinone, N,N'-dimethylimidazolidinone, etc. in an organic solvent is interposed, and current is passed between the positive and negative electrodes (electrical capacity An example of this method is a method in which the amount of thermal decomposition products of the arylacetylene polymer is 03 to 2 All per 1 g of the thermal decomposition product of the arylacetylene polymer. Chemical methods include thermal decomposition products of alkyllithium or aryllithium with aliphatic hydrocarbons such as hexane.

An example of this method is immersion in an organic solvent solution such as ether such as tetrahydrofuran (concentration is usually 5 to 50% by weight).The immersion or impregnation temperature is usually 5 to 30%.
°C and time is usually 1 to 50 hours.

Further, as a physical method, there is a method of exposing the thermal decomposition product to lithium vapor. Preferred among these methods are electrochemical methods and chemical methods.

The negative electrode material for lithium secondary batteries of the present invention is usually prepared by impregnating lithium into a thermal decomposition product of an arylacetylene polymer in the form of a film or a woven fabric by the method described above, or by impregnating lithium with the thermal decomposition product of an arylacetylene polymer in the form of a powder. Thermal decomposition products are mixed with powdered synthetic resins (Teflon, polyethylene, polyethylene, etc.) or petroleum or petroleum dry distillates such as pitch and tar, mixed together, and then heated and molded to form the above-mentioned product. The power obtained by the method of containing lithium≦
can.

Using the negative electrode material for lithium secondary batteries of the present invention.

An example of a lithium secondary battery will be explained based on FIG. 1. In the figure (υ is a positive electrode can (positive electrode current collector), (2) is a metal net for current collection, (3) is a positive electrode active material, (4) is a separator containing an organic electrolyte, and is a molded separator or electrolyte. (6) is a negative electrode active material (negative electrode material for a lithium secondary battery of the present invention), (7) is a negative α can (negative electrode current collector), and (8) is a metal net for current collection.

Examples of the positive electrode current collector (1) include conductive materials such as stainless steel and carphone. Examples of the positive electrode active material (3) include transition metal oxides (manganese dioxide, vanadium pentoxide, molybdenum oxide, copper oxide, etc.), transition metal chalcokene compounds (iron sulfide, titanium sulfide, etc.), and the like. The positive electrode active material is generally used as a molded body, and the method for obtaining the molded body is to press positive electrode active material powder or positive electrode active material powder and synthetic resin powder (powder of Teflon, polyethylene, polystyrene, etc.) in a mold. One example is sintering. The organic electrolyte (4) is a bath solution of the above-mentioned lithium salt (lithium perchlorate, etc.) in the above-mentioned organic solvent (propylene carbonate, etc.) [the concentration of the lithium salt is the same as M o, x
~5 mol/(1), and the molded electrolyte includes the above-mentioned lithium salt, the organic polymer Cnu (aryl acetylene polymer recarbonate, etc.), and the organic solvent C-propylene carbonate, etc.). It will be done. Examples of the negative electrode current collector in (7) include stainless steel, katana-yo, pa-/chi-g.

Next, a lithium secondary battery using the negative electrode material of the present invention will be specifically explained. A current collecting metal net (2) is placed on the bottom of the positive electrode can (1) 1, and a positive electrode active material (molded body) (3) is placed on top of it.
Crimp. Next, a separator containing an organic electrolyte or a molded electrolyte (
4), insert the L-shaped gasket (5) along the wall of the positive electrode can (1). Next, the negative electrode active material (6
) is brought into close contact with the negative electrode can (7) with a current collecting metal net interposed therebetween, and then placed on the north side of the separator or electrolyte molded body (4) containing an organic electrolyte, and then opened the positive electrode can (1). Fold the part inward and seal it.

The negative electrode material for lithium secondary batteries of the present invention is easy to synthesize and has excellent charge/discharge characteristics, and is a negative electrode material that hardly causes problems such as dendrites during charging.
Lithium batteries using lithium batteries are of high performance.

Production Example 1 Poly 2-chloro-1-phenylacetylene powder 489
was placed in a quartz tube installed in an electric furnace, and while passing nitrogen gas through the quartz tube, the temperature was raised from room temperature to 400°C in 1 hour, then the humidity was raised from 400°C to 600°C in 30 minutes, and then Raise the temperature from 600℃ to 800℃ in 30 minutes, and
Heated at 0°C for 25 hours. After that, it was cooled while passing nitrogen gas, and a black powdery substance, poly-2-chloro-1, was produced.
- Phenylacetylene polymer thermal decomposition products 26.89
Obtained. This material remains stable without oxidative decomposition even if left in the air for 6 months.

This thermal decomposition product lOJ and 1 g of polyethylene powder were mixed and kneaded well, then put into a mold and heated to 300 kg/cr.
A molded product of poly-2-chloro-1-phenylacetylene thermal decomposition product having a thickness of 1 mm was obtained under a pressure of 1'G. The electrical conductivity of this material is 01Ω-'cm' at room temperature.
Met.

Example 1 The sheet (molded body of thermal decomposition product of poly-2-chloro-1-phenylacetylene polymer) prepared in Production Example 1 was cut into a disk shape with a diameter of 1 cm, and the weight was measured.
m & de attu tko. Crimp this onto a stainless steel net and
The powder was used as a positive electrode, the lithium foil was used as a negative electrode, and both electrodes were placed in a glass container containing a propylene carbonate solution in which lithium peroxide was dissolved to a concentration of 0.5 mono, 2/β, and the electrodes were sealed.

Next, a constant current of 0.5 mA was applied for 30 hours. As a result, a disc-shaped tube containing 4 ml of lithium (negative electrode material for a lithium secondary battery of the present invention) was obtained.

Reference Example 1 The lithium-containing disc-shaped node obtained in Example 1 (negative electrode material for lithium secondary batteries of the present invention) was used as a negative electrode active material,
A lithium secondary battery was assembled using vanadium pentoxide as a positive electrode active material and an N-methyloxazolidinone solution of lithium perchlorate as an electrolyte. Charging was performed at a constant current of 0.5 mA until the final voltage reached 8.5 V. This charge/discharge test was conducted for 30 cycles, and the results showed good reversibility.

Example 2 Vanadium pentoxide powder, acetylene black and polyethylene powder were mixed and kneaded well, then put into a mold and molded under a pressure of 500 kg/cm2G to a thickness of 1.5 nm.
An un disk (molded body of positive electrode active material) was obtained.

After this disk was crimped onto a stainless steel net inside a cylindrical polyethylene container, 6mf lithium foil was
there was. Next, N− of lithium perchlorate with a concentration of 0.5 mol/e
A sponge-like liquid-absorbing sheet 1- (separator containing an organic electrolyte) impregnated with a methyloxazolidinone solution was placed on a lithium foil. The sheets 1 to 1 prepared in [Manufacturing Example] were cut out into a disc shape with a diameter of 1.2 cm, and the discs were crimped onto a stainless steel net, placed on the liquid absorbent sort, and both ends of the polyethylene container were sealed with caps. [At this time, attach lead wires to the stainless steel net I and the lithium foil. ). A constant current of 0.5 mA was applied for 23 hours using a lithium foil as a negative electrode and a molded product of a thermal decomposition product of poly2-chloro-1-phenyl≠4=acetylene polymer as a positive electrode. As a result, all of the lithium foil was consumed and lithium was contained in the molded product of the thermal decomposition product, thereby obtaining a negative electrode material.

Reference Example 2 In Example 2, the molded body of the thermal decomposition product containing lithium was used as the negative electrode active material, and a charge/discharge test was conducted for 30 cycles under the same conditions as in Reference Example 1. As a result, good reversibility was shown. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view. 3... Positive electrode active material, 4... Separator or electrolyte molded body containing an organic electrolyte, 6... Negative electrode active material 1 figure March 31, 1958 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 28974 of 1989 2. Name of the invention RINAU/, Negative electrode material for secondary batteries 3. Spontaneous amendment by the person making the amendment 5. Amendment The number of inventions increases by 6, [Detailed Description of the Invention-1 column of the specification to be amended, -:'-, '1r-', -°. 7. Contents of the amendment As shown in the attached sheet (1) Between lines 8 and 9 of page 16 of Book Ming G'a, ``
Example 3 Thermal decomposition product of poly-2-chloro-1-7 enyl acenale obtained in Production Example 1 (hereinafter referred to as PPCA-B) 0.9
7 and 01 g of polyethylene fine powder (Binder using PPCA-B negative electrode) were mixed and kneaded well. Put 0.1 g of the kneaded material into a mold, heat it to about 60'C, and heat it to 500 kq/1'.
Molded under CAG pressure, diameter 10mm, thickness Q, 7
A disc-shaped molded body of mff1 was created. The disk-shaped molded body was compressed into a spanless nail. Next, 0.35 g of electrolytic manganese dioxide powder, 0.059 J of acetylene black:) and 0.19 Teflon powder were added to
Combine and create 7 kon and east 1-/i='1-mi1
Cut out two discs of 20 mm in diameter and press them onto a stainless steel foil in the shape of a square. Its, about 0.15!7 lithium foil is crimped onto a stainless steel plate. Each is crimped to a stainless steel non-71” t:P P
The CA-B molded body, the manganese dioxide molded body, and a power lath machine containing 25 ml of an electrolyte solution (7 volumes of Li C104 propylene carbonate with a concentration of 1 mol/min)
(inner volume 50πt) (inner volume 50πt) (-2 sealed (at this time, attach a lead wire to each of the stainless steel tubes). The following tests were conducted using a Hokuto Denko ◇Rokusha charge/discharge device HJ-201 with lithium foil as the negative electrode and manganese dioxide as the positive electrode.
．． Discharged at 5mA constant current for 20 hours [1,]/Mno2
Inter-discharge time, 20 hours (], OmA,b)). Next, PPCA-B was used as the negative electrode, and Lithium 1. 0.5111 using the above device as a positive electrode containing manganese dioxide.
A constant current (charged for 5 hours, P CA -I) was made to contain Linau/, to obtain negative electrodes + and I of the present invention. , followed by containing lithium],' i] CA-1'i was used as a negative electrode, and the manganese dioxide was heated for 141 minutes! The charging and discharging characteristics were measured by repeating charging and discharging (0.5 mA constant current) (-t:).The results are shown in Table 1. However, the problem of the Σ-'nd light did not occur, and there was a negative electrode for the second, weaker secondary voltage that would be destroyed during the charging and discharging process. Measure the charge/discharge characteristics
:. 1) I) Bonding and cutting for CA-13 negative electrode material: Teflon powder 0.04 mm electrolytic solution ゛1 mol/4
．． Agricultural Li1) F6N-methyloxacyl/non/tetrahydrofuran (volume ratio)/] C match 7 volume 7 night ■, i/MnO2 discharge time: 30 hours (15 mA
As shown in Table 2, the results obtained show that the negative electrode material of the present invention has high charge/discharge efficiency, does not cause the problem of light oxidation, and is less likely to be destroyed during the charge/discharge process. There was an excellent negative electrode material for dielectric batteries. Table 2 Comparative Example 1 Charging and discharging characteristics were measured under the same conditions as in Example 3 using Grapheye l- instead of PPCA and -H. The obtained results are shown in Table 3. Table 3 As shown in Table 3, the negative electrode material containing lithium had very low charging and discharging efficiency. Moreover, it gradually broke during the charging and discharging process. ” Insert -1-ru.

Claims (1)

[Claims] 1. A negative electrode material for a lithium secondary battery containing lithium in a thermal decomposition product of an arylacetylene polymer.