JPH0534781B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel orthoester derivative coated polyacetylene composites, methods of making and using the same. It has been well known that oxygen-containing organic compounds such as crown ethers have a specific interaction function with cationic species such as Li ⁺ , Na ⁺ , K ⁺ , and the like. In the course of broadly studying the functions of such oxygen-containing organic compounds, the present inventors discovered a new orthoester derivative, which has specific interactions with cationic species such as Li ⁺ , Na ⁺ , K ⁺ , etc. It was found that it has an action function. That is, the basic characteristics of the orthoester derivatives include (a) ionic conductivity, (b) specific interaction with alkali metal ions, and (c) protective action against anionic species. It has been found that this has an extremely significant stabilizing effect on the n-doped product. In recent years, USP-4204216 and USP-4222903 have shown that conjugated polymers such as polyacetylene are
It has been disclosed that doping or p-doping with anionic species exhibits amazing electrical conductivity, and furthermore, EP-36118 proposes a secondary battery using such a conjugated polymer such as polyacetylene, which has extremely high conductivity. It is attracting attention as a new high-capacity secondary battery. Among these, polyacetylene n-doped with cationic species is particularly expected to be a promising candidate as a negative electrode active material for non-aqueous secondary batteries, which is in great demand in the secondary battery industry. However, the EP-
As described in No. 36118, the n-doped polyacetylene has extremely unstable properties, and this instability has been a major hindrance to its practical application. The instability of such n-doped polyacetylene is understood to be essentially due to the chemically extremely active carbanion-like structure, and it has been thought that it is nearly impossible to improve its stability. However, as a result of intensive studies from various viewpoints, the present inventors found the general formula (): [M represents at least one selected from the group of alkali metals. Z ₁ and Z ₂ are the same or different and are a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, an alkyl group or an aryl group; a group substituted with at least one substituent selected from the group consisting of; or

[Formula] represents a group in which n is 2 to 5. ] We discovered a new orthoester derivative shown by
It was discovered that the orthoester derivative has an extremely significant stabilizing effect on n-doped polystyrene, and the present invention was completed. According to the present invention, first, the general formula (): [M represents at least one selected from the group of alkali metals. Z ₁ and Z ₂ are the same or different and are a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, an alkyl group or an aryl group; a group substituted with at least one substituent selected from the group consisting of; or

[Formula] represents a group in which n is 2 to 5. ] At least one orthoester derivative represented by
A polyacetylene composite is provided, characterized in that the polyacetylene polymer is coated with a seed. The orthoester derivative referred to in the present invention is represented by the general formula (), where M represents an alkali metal such as lithium, sodium, or potassium. The number of carbon atoms in the straight chain alkylene group in general formula () or the number of carbon atoms in the straight chain alkylene moiety of the substituted straight chain alkylene group is in the range of 2 to 5. When the number of carbon atoms is 6 or more, the interaction function with the cationic species of the compound is poor, which deviates from the spirit of the present invention, and when the number of carbon atoms is 1, it is difficult to synthesize the compound. . Also, in the general formula ()

n in the formula is selected from a range of 3 to 5. When n is 2 or less, the ring is highly distorted and unstable, and when n is 6 or more, synthesis is difficult. Examples of the substituent of the substituted linear alkylene group include a halogen atom, an alkyl group, and an aryl group.
Examples of halogen atoms include fluorine, chlorine, bromine, and iodine, and examples of alkyl groups and aryl groups include methyl, ethyl, n-propyl, iso-butyl, n-pentyl, phenyl, tolyl, naphthyl, and 4- Examples include groups such as methoxyphenyl and 4-chlorophenyl. As a method for obtaining the orthoester derivative of the present invention, general formula ():

[Formula] [Z is a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of a straight chain alkylene group having 2 to 5 carbon atoms is at least one hydrogen atom selected from the group consisting of a halogen atom, an alkyl group, and an aryl group. a group substituted with a substituent of species; or

[Formula] represents a group in which n is 3 to 5. ] A method using a reductive coupling reaction of a cyclic carbonate compound is mentioned. As a reductive coupling method, (a) a method in which an organometallic complex of an alkali metal such as lithium, sodium, potassium, etc. and biphenyl, naphthalene, anthracene, etc. is reacted with a compound represented by the general formula (). (b) In a supporting electrolyte containing at least one of alkali metal ions such as lithium ions, sodium ions, and potassium ions, the general formula ()
A method of electrochemically reducing the compound shown in etc. In carrying out the method (a), the organometallic complex is reacted with () in a solvent such as tetrahydrofuran, dimethoxyethane, diethoxyethane, diethyl ether, etc. The reaction temperature is not particularly limited, but is arbitrarily selected within the range of -100°C to 100°C. To carry out the method (b), electrochemical reduction is carried out in an electrolytic solution consisting of an electrolyte and (2) and, if necessary, a solvent, which will be described later. At that time, the reduction potential is - compared to the standard lithium electrode.
Perform within the range of 0.1V to +2.5V. In such a method,
Orthoester derivatives are generated on or near the electrode surface. The novel ester derivative of the present invention is an extremely useful compound that exists stably in the absence of protic compounds such as water, has solid ionic conductivity, and has the ability to interact with alkali metal ions. Specific examples of the novel orthoester derivatives of the present invention and the cyclic carbonate starting materials are as follows:

【table】

[Table] etc. As mentioned above, the novel orthoester derivative of the present invention has ionic conductivity and the ability to interact with alkali metal ions, and exhibits extremely surprising effects when combined with n-doped polyacetylene. That is, the effect is that the n-doped polyacetylene coated with the orthoester derivative is extremely stabilized. The polyacetylene referred to in the present invention is obtained by polymerizing acetylene and, if necessary, a copolymerizable monomer in the presence of a Ziegler type catalyst consisting of a transition metal compound and an organometallic compound, a catalyst consisting of a transition metal compound and a reducing agent, etc. It can be easily obtained in the form of a film, powder, or gel. It is a well-known fact that the polyacetylene easily undergoes p-type doping through reaction with an electron-accepting compound or electrochemical oxidation reaction, and easily undergoes n-type doping through reaction with an electron-donating compound or electrochemical reduction reaction. It is. Among these, n-type doped polyacetylene in particular has attracted attention for its unique properties as described above, but has not been put into practical use due to its instability. By coating n-doped polyacetylene with the novel orthoester derivative of the present invention,
Its stability against oxygen, carbon dioxide, reactive solvents, etc. is dramatically improved. Furthermore, as will be described later, it has a very significant effect on electrochemical reversible stability. The coating method includes a method in which a solution of the olethoester derivative prepared by the above-mentioned method is dissolved in a solvent is coated on polyacetylene or its n-doped product. Suitable solvents that can be used here include aprotic solvents such as dimethylformamide, dimethylacetamide, and dimethylsulfoxide. Alternatively, there is a method in which the orthoester derivative is formed and coated directly on the surface by an electrochemical reduction reaction using polyacetylene as an electrode. The latter method is suitable for forming extremely thin coating layers. To carry out this method, an electrolytic solution containing a cyclic carbonate compound represented by the general formula () and at least one ion selected from the group of alkali metals such as Li ⁺ , Na ⁺ , K ⁺ etc. The reduction may be carried out electrochemically using polyacetylene as an electrode. By this operation, the coating reaction produced by the orthoester derivative and the n-doping of polyacetylene proceed simultaneously. In this case, the cyclic carbonate ester may be used as it is as the electrolyte solvent, or it may be diluted or dissolved in another solvent. The amount of the cyclic carbonate used is in the range of 0.1 to 100% by weight (weight% excluding electrolyte) in the electrolyte solvent, particularly 10 to 100% by weight (weight% excluding electrolyte).
A range of 100% by weight is preferred. As the other solvent used, an aprotic solvent that is electrochemically stable in the potential range in which the reduction reaction proceeds is selected. Such solvents include tetrahydrofuran, methyltetrahydrofuran, dimethoxyethane, diethyl ether, acetonitrile, propionitrile, benzene, toluene, xylene, anisole, and the like. The electrolytes that make up the electrolyte include LiClO ₄ ,
LiCl, _LiBF4 , LiBr, _LiPF6 , _{CH3SO3Li ,
CF3SO3Li} , _{NaClO4 , NaBF4} , _NaPF6 ,
_{CH3SO3NaCF3SO3Na , KPF6 , CH3SO3K , _}
Examples include CF ₃ SO ₃ K. The potential range in which the electrochemical reduction reaction proceeds is -0.1V with respect to the lithium standard electrode potential.
~+2.5V, more preferably 0.0V to +1.8V when using lithium ions, +0.3V to +1.8V when using sodium ions, and +0.1V to +1 when using potassium ions. A range of 8V is particularly preferred. The total amount of electricity to be applied to cause the electrochemical reduction reaction is preferably 30 to 80 mol %, preferably 35 to 70 mol %, per polyacetylene CH unit. Here, the amount of electricity Q (in ampere hours) corresponding to the doping amount A mol % per polyacetylene CH unit is determined by the following equation. A=Q/W/13×26.8×100 where W is the weight of the polyacetylene used (graph unit). As mentioned above, the n-doped polyacetylene coated with the novel orthoester derivative of the present invention is very stable. It becomes electrochemically extremely stable and reversible, and exhibits extremely excellent performance as a negative electrode active material for nonaqueous secondary batteries and solid electrolyte secondary batteries.Such secondary batteries are manufactured. In this case, an n-type doped or undoped polyacetylene coated with the novel orthoester derivative of the present invention obtained by the above method may be assembled as a negative electrode, and in the case of a non-aqueous secondary battery, If the electrochemical coating treatment solution described above is used as a secondary battery electrolyte, the electrochemical coating treatment will be conveniently performed during the initial charging process.The positive electrode active material of such a secondary battery is not particularly limited, but may include the following:
FeS ₂ , TiS ₂ , TiS ₃ , MnO ₂ , Li _1-x CoO ₂ (but 0
<x≦1), V ₂ O ₅ , MoO ₃ , CuF ₂ , and further selected from positive electrode active materials such as P-type polyacetylene, P-type polyparaphenylene, and P-type polypyrrole. In addition, as a nonaqueous electrolyte, organic solvents represented by tetrahydrofuran, dimethoxyethane, sulfolane, methylsulfolane, propylene carbonate, ethylene carbonate, γ-butyrolactone, acetonitrile, propionitrile, etc.
LiClO ₄ , LiCl, LiBr, LiBF ₄ , LiPF ₆ , NaClO ₄ ,
A solution containing an electrolyte such as NaBF ₄ , NaPF ₆ , CH ₃ SO ₃ K, CF ₃ SO ₃ KKPF ₆ , etc. is used. In addition, although the solid electrolyte is not particularly limited,
LiI, LiI (Al ₂ O ₃ ), Li ₃ N, Na ₃ Zr ₂ SiPO ₁₂ ,
K ₂ O・5.2Fe ₂ O ₃・0.8ZnO, etc. are used. The n-doped polyacetylene coated with the novel orthoester derivative of the present invention is extremely stabilized, and a secondary battery using it as a negative electrode active material has excellent long-term charge/discharge cycle performance, self-discharge characteristics, voltage maintenance characteristics, etc. In terms of performance, it shows an amazing improvement in performance compared to the case of using conventional n-type polyacetylene, and is extremely useful as a practical new type of secondary battery. The present invention will be explained in more detail below with reference to Examples. Example 1 - Production of polyacetylene - This example shows a method for preparing polyacetylene used in the following examples. Under an N ₂ atmosphere, 50 ml of toluene was placed in a glass container with an internal volume of 800 ml, and 6 ml of tetrabutoxytitanium and 10 ml of triethylaluminum were added to prepare a catalyst. After cooling the container to -78°C, the system was evacuated, a catalyst liquid was applied to the wall of the container, and acetylene gas was introduced. A film of polyacetylene immediately forms on the wall,
After standing for 15 minutes, the system was evacuated. 0.5N−HCl−
After washing with MeOH five times, it was dried and taken out. This film-like polyacetylene was heat-treated at 250° C. for 5 seconds and then used in the following examples. Example 2 1.28g of naphthalene in 100ml of tetrahydrofuran
After dissolving in the solution, 0.14 g of lithium metal was added and stirred at room temperature for 2 hours to obtain a lithium-naphthalene complex. When 2.5 g of propylene carbonate was added dropwise to this solution, a light brown precipitate was immediately obtained. The precipitate was separated in N ₂ and washed with benzene, and then dried to obtain 2.1 g of a powdered product. The analysis results of this powdered product are shown in Tables 1 and 2.
As shown in the figure. The molecular weight was determined by the freezing point depression method using dimethyl sulfoxide as a solvent. Further, NMR was measured in DMSO-d6 solvent, and infrared spectrum was measured by KBr method.

[Table] Example 3 After dissolving 1.54 g of biphenyl in 100 ml of dimethoxyethane, 0.46 g of sodium metal was added and stirring was performed at room temperature for 2 hours to obtain a sodium-biphenyl complex. Add 2.5g of ethylene carbonate to this solution.
A light brown precipitated product was obtained. The precipitate was separated in N ₂ and washed with benzene, and then dried to obtain 1.9 g of a powdered product. The same analysis as in Example 2 was conducted on this powdered product. The results are shown in Table 2.

[Table] Examples 4 to 6 1.78 g of anthracene was added to 100 g of tetrahydrofuran.
ml, 0.46 g of potassium metal was added and stirred at room temperature for 2 hours to obtain a potassium-anthracene complex. When 2.5 g of each of the cyclic carbonate esters shown in Table 3 were added to this solution, light brown precipitated products were obtained in each case. After carrying out the same operation as in Example 2, each powdered product was obtained. Table 3 shows the results of each analysis.

【table】

[Table] Example 1 A three-electrode electrochemical reaction system was set up using 0.6M-LiClO ₄ -propylene carbonate solution as the electrolyte, 13mg of polyacetylene as the working electrode, 50mg of lithium metal as the counter electrode, and lithium metal as the reference electrode. Then, current was applied at a constant current of 5 mA for 2.3 hours using the working electrode as a cathode. Amount of electricity supplied at this time Q=
The amount of electricity was 0.0115 hours, which was equivalent to the doping amount A=42.9%. During this time, the potential of the working electrode polyacetylene relative to the reference electrode changed from +2.7V to +0.1V. Next, when the working electrode was used as an anode and energized with a constant current of 5 mA, the potential of the working electrode was +2.5V.
It took 1.1 hours to reach this point. Thereafter, the electrolyte was removed, and the polyacetylene was washed with propylene carbonate and benzene in that order, and then dried. The infrared spectrum of this polyacetylene measured after drying is shown in FIG. Further, FIG. 3 shows the results of a difference spectrum measured using untreated polyacetylene as a reference sample. A covering layer is clearly formed,
Furthermore, this spectrum coincided with the spectrum of the product obtained in Example 2 (FIG. 1). From the above, it was found that what was obtained here was a polyacetylene composite formed by coating a polyacetylene polymer with the orthoester derivative obtained in Example 2. Next, this polyacetylene was immersed in methanol, washed, and then dried. Figure 4 shows the infrared spectrum at this time. This spectrum matched that of the original polyacetylene (Figure 5). Comparative Example 1 The same procedure as in Example 1 was performed except that propylene carbonate was replaced with tetrahydrofuran. The infrared spectrum of polyacetylene after washing with tetrahydrofuran is shown in FIG. This spectrum matched that of the original polyacetylene, indicating that no coating layer was formed. Example 2 The same electrical treatment as in Example 1 was carried out except that propylene carbonate was changed to 1,3-propanediol carbonate/benzene (50/50 weight ratio). At this time, the amount of electricity Q was 0.0113 AHr, and the amount of electricity was equivalent to the doping amount A = 42.2%. During this time, the potential of the working electrode polyacetylene relative to the reference electrode changed from 2.7V to +0.1V. Next, when the working electrode was used as an anode and a constant current of 5 mA was applied, the voltage reached +2.5 V in 1.1 hours.
It was washed and dried in the same manner as in Example 1. When we measured the infrared spectrum of this polyacetylene, we found that everything other than the absorption of polyacetylene was new.
2850~3000cm ^-1 , 1625cm ^-1 , 1400cm ^-1 , 1315cm
Absorption was observed at ^-1 and 1095 cm ^-1 , which matched the spectrum of the compound obtained in Example 4. Example 3 The same energization treatment as in Example 1 was performed except that propylene carbonate was changed to propylene carbonate/ethylene carbonate (50/50 weight ratio). At this time, the amount of electricity Q was 0.0110 AHr, and the amount of electricity was equivalent to the doping amount A = 41.0%. During this time, the potential of the working electrode polyacetylene with respect to the reference electrode is 2.7V
It changed from 0.1V to 0.1V. Next, when the working electrode was used as an anode and a constant current of 5 mA was applied, the voltage reached +2.5 V in 1.1 hours. After washing and drying in the same manner as in Example 1, the infrared spectrum was measured, and the range was 2850 to 3000 cm.
^-1 , 1635~1670cm ^-1 , 1400~1410cm ^-1 , 1310~
New absorption was observed at 1320cm ^-1 and 1095cm ^-1 . Example 4 1.3g of polyacetylene as negative electrode, as positive electrode
Using 3.7 g of LiCoO ₂ and a 0.6M LiBr-ethylene carbonate/benzene (50/50 weight ratio) solution, a paver-type battery shown in FIG. 7 was fabricated. In FIG. 7, 1 is an exterior film made of Al-laminated polyethylene, and 2 is a positive electrode current collector made of platinum-plated nickel foil with a thickness of 50 μm and 5 cm×5 cm, which is welded to the exterior film 1. 3
is a positive electrode active material, 4 is a separator made of polypropylene nonwoven fabric, 5 is a negative electrode active material, and 6 is a thickness of 50μ
This is a negative electrode current collector made of nickel foil measuring 5 cm x 5 cm. This battery tree was initially charged for 120 hours at a constant current of 10 mA. At this time, the amount of electricity Q = 1.2AHr,
The amount of electricity was equivalent to the doping amount = 44.8%. Next, it was discharged to 2.5V at a constant current of 50mA. After the above treatment, a constant current charge/discharge test of 50 mA was conducted under conditions of a charge end voltage of 4.5V and a discharge end voltage of 2.5V. The cycle results are shown in Figure 8a. Comparative Example 2 In Example 2, 3.7g of LiCoO ₂ was replaced with 3.7g of natural graphite.
I made a prototype of the same paper type battery, except for changing it to . From the beginning, set this battery to the end-of-charge voltage.
A constant current charge/discharge test of 50 mA was performed under the conditions of 4.5 V and a discharge end voltage of 2.5 V. The cycle results are shown in Figure 8b.

[Brief explanation of the drawing]

1 to 6 show infrared absorption spectra, FIG. 7 is a schematic sectional view of the paper type battery, and FIG. 8 is a graph showing the cycle test results. In FIG. 7, 1 is an exterior film, 2 is a positive electrode current collector, 3 is a positive electrode active material, 4 is a separator, and 5 is a positive electrode current collector.
is a negative electrode active material, and 6 is a negative electrode current collector. In FIG. 8, a shows the results of Example 4, and b shows the results of Comparative Example 2.

Claims (1)

[Claims] 1 General formula (): [M represents at least one selected from the group of alkali metals. Z ₁ and Z ₂ are the same or different and are a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, an alkyl group or an aryl group; a group substituted with at least one substituent selected from the group consisting of; or a group in which n in the formula is 2 to 5; ] At least one orthoester derivative represented by
A polyacetylene composite comprising a polyacetylene polymer coated with seeds. 2 A polyacetylene polymer is used as an electrode, and the general formula (): [Formula] [Z is a straight chain alkylene group having 2 to 5 carbon atoms; or the hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, Represents a group substituted with at least one substituent selected from the group consisting of an alkyl group and an aryl group; or a group in which n in the formula is 3 to 5. ] General formula (): [M represents at least one selected from the group of alkali metals. Z ₁ and Z ₂ are the same or different and are a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, an alkyl group, or an aryl group; represents a group substituted with at least one substituent selected from the group consisting of groups; or a group in which n in the formula is 2 to 5; ] A method for producing a polyacetylene composite, which comprises coating a polyacetylene polymer with an orthoester derivative represented by the following. 3 General formula (): [M represents at least one selected from the group of alkali metals. Z ₁ and Z ₂ are the same or different and are a straight chain alkylene group having 2 to 5 carbon atoms; or a hydrogen atom of the straight chain alkylene group having 2 to 5 carbon atoms is a halogen atom, an alkyl group, or an aryl group; represents a group substituted with at least one substituent selected from the group consisting of groups; or a group in which n in the formula is 2 to 5; ] A method for using a polyacetylene composite, which comprises using an n-doped polyacetylene composite coated with an orthoester derivative as a negative electrode active material for a secondary battery.