JPH0532422B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a (meth)acrylate (co)polymer having oligoethylene oxide in the side chain represented by general formula (1), LiClO ₄ or LiBF ₄ (or
an inorganic lithium salt selected from LiPF ₆ ),
This invention relates to a conventional hybrid ion conductor formed by mixing in a weight ratio of 99/1 to 50/50. [Here, R is H or CH ₃ , R' is a carbon number of 1 to 6
an alkyl group, n is an integer of 5 to 20, x is 100 to 50
%, x + y = 100%] The polymer-inorganic lithium salt hybrid ion conductor was devised to provide good moldability while maintaining high ionic conductivity, and is particularly suitable for use as electronics components. thought,
An important issue is that it can be made into a thin film. A solid electrolyte in which a predetermined amount of LiClO ₄ is dispersed in high molecular weight polyethylene oxide [JEWeston et al., Solid
State Ionics, 2 , 347 (1981)], but all of these have poor flexibility and have a conductivity of only 10 ^-7 to ^{10 -4} S/cm. The hybrid solid ionic conductor of the present invention has oligoethylene oxide, which has a very low glass transition point, in its side chain as a group that interacts with lithium ions, and has a (meth)acrylate main chain to maintain film-forming properties. Since it is a hybrid of a polymer having the structure 1) and an inorganic lithium salt, it is characterized by having both high ionic conductivity and good film-forming ability. In formula (1), the (meth)acrylate alkyl ester copolymer unit is introduced to change the film formability, and y may be 0%, and R′ y should be close to 50% by using a long-chain alkyl. There is almost no difference between R=H and CH ₃ , but a slightly harder film can be obtained with R=CH ₃ . The inorganic lithium salt obtained in the present invention includes LiClO ₄ ,
They were selected from LiBF ₄ and LiPF ₆ , and although there are no major differences, LiClO ₄ and LiPF ₆ are selected from the viewpoint of compatibility with the polymer of formula (1) and ionic conductivity of the hybrid.
Superior to LiBF ₄ . The hybrid solid ionic conductor of the present invention has the formula (1)
The polymer and the above-mentioned lithium salt can be uniformly dissolved in tetrahydrofuran, methanol, acetone, etc. to form a cast film, or if R' is an alkyl group having 2 or less carbon atoms and y = 15% or less, the polymer It is possible to melt-cast by heating and homogeneously mixing the inorganic lithium salt and the inorganic lithium salt to about 200°C, and it is also possible to pressurize and/or heat mold. however,
There is a risk of explosion when using LiClO ₄ , so
It is necessary to pay attention to the heating temperature. Alternatively, if a mixture of monomers corresponding to formula (1) and an inorganic lithium salt are kneaded in advance and heated in an inert atmosphere, spontaneous polymerization occurs and the desired hybrid solid ionic conductor is obtained. The polymer used here or the polymer in the hybrid obtained by natural polymerization has a molecular weight in the range of 10,000 to 500,000. The mixing ratio of the polymer in formula (1) and the inorganic lithium salt is
A weight ratio of 99/1 to 50/50 will exhibit the specified performance, but as the proportion of inorganic lithium salt increases, the ionic conductivity will gradually increase.
It is preferable to approach 50/50. However, if the amount of inorganic lithium salt is increased beyond this range, the film becomes brittle due to the formation of microcrystals. The ion conductor of the present invention can be incorporated into electrolytic capacitors, batteries, electrochronic display devices, etc. as a solid electrolyte. Also,
It can also be used as a non-static material. Next, the hybrid solid ion conductor of the present invention will be explained with reference to Examples, but first, the synthesis of the polymer of formula (1) and the monomer of the x unit portion corresponding thereto will be shown in Experimental Examples. Experimental Example 1 20 g of one-end methyl ether oligoethylene oxide having a molecular weight of 250 (n≈5) was dissolved in 200 ml of anhydrous THF, and 5 g of metallic lithium was added under boiling reflux. After one day of reaction, remove excess metallic lithium and
Add 10 g of methacrylic acid chloride while cooling to ℃.
A solution diluted with 50 ml of THF was added dropwise, and
The reaction was allowed to proceed at room temperature for 5 hours. Concentrate under reduced pressure to about 100 ml, develop with CHCl ₃ in a basic alumina column with a diameter of 10 cm and a length of 30 cm to remove excess methacrylic acid chloride and by-produced LiCl, and obtain one-terminated methyl ether oligoethylene oxide methacrylate. A _CHCl3 solution was obtained. As a result of fractionating and analyzing a small amount of this solution, the yield was approximately 22 g, which was determined by nuclear magnetic resonance. a: 2.0 (3H), b, c: 5.5, 6.1 (2H), d: 4.2
(2H), e: 3.6 (18H), f: 3.3 (3H) ppm (CDCl ₃
The structure of formula (2) was confirmed. Experimental Examples 2 to 5 Exactly the same as Experimental Example 1, except that the molecular weight was 350, (n≒
8) (Example 2), 550 (n≒13 (Experimental Example 3), 750 (n
≒17) (Experimental Example 4), 900 (n≒20) (Experimental Example 5) one-terminal methyl ether oligoethylene oxide 20
The corresponding methacrylate monomers were obtained using 1 g each. Yields are 21g, 20g, 19g, and 19g, respectively.
g, and the e proton ratio is different, as in Experimental Example 1.
gave a similar nuclear magnetic resonance spectrum. Experimental Examples 6 to 10 Same as Experimental Examples 1 to 6, except that acrylic acid chloride was used, and the molecular weight was 250 (Experimental Example 6), 350 (Experimental Example 7), 550 (Experimental Example 8), 750 (Experimental Example 9), 900 (Experiment Example 10) was used to obtain 21 g, 20 g, 19.5 g, 19 g, and 18.7 g of the corresponding acrylate monomers using 20 g of one-end methyl ether oligoethylene oxide. Compared to Experimental Examples 1 to 5, similar nuclear magnetic resonance spectra were given except for the disappearance of the a proton in formula (2). Experimental Examples 11-20 CHCl ₃ from the monomer solutions obtained in Experimental Examples 1-10
was distilled off, and the monomers shown in Table 1 were prepared as such or together with comonomers for 12 hours under degassing.
Polymerization was carried out at 60°C, and the product was dialyzed into an aqueous solution and then dried under reduced pressure to obtain the corresponding copolymer as shown in Table 1. x% in the polymer [see formula (1)] was determined by nuclear magnetic resonance method.

[Table] The molecular weights of these (co)polymers were determined by light scattering to be 15,000 (Example 11), 22,000 (12), and 22,000 (12), respectively.
13000 (13), 10100 (14), 35000 (15), 78000 (16)
,
170000 (17), 495000 (18), 32000 (19), 43000 (20
)
It was hot. Examples 1 to 10 The monomer CHCl ₃ solutions of Experimental Examples 1 to 10 were distilled off under reduced pressure to change to THF solvent, mixed with inorganic lithium salt in the ratio shown in Table 2, and spread on a Teflon plate.
THF was evaporated and polymerization was carried out by standing under reduced pressure for 12 hours and at 60°C for 12 hours. The ionic conductivity of the obtained thin film was determined by measuring the current by applying an alternating current voltage of 100 to 20,000 Hz and performing a complex impedance plot using a graphite/membrane/graphite cell configuration. The results are summarized in Table 2. A portion of the obtained membrane was dissolved in water and dialyzed for two days to obtain a solution containing only the polymer, and the molecular weight was determined by light scattering method, and the results were 18,000 (Example 1), 23,000 (2), and 23,000 (2), respectively. 26000 (3), 34000 (4), 17000
(5), 38000 (6), 71000 (7), 122000 (8),
They were 65,000 (9) and 44,000 (10).

[Table] Examples 11 to 20 The polymers of Experimental Examples 11 to 20 were mixed with an inorganic lithium salt in THF or methanol as shown in Table 3, and spread on a Teflon plate to slowly evaporate the solvent. After that, it was dried under reduced pressure at 60°C, and Example 1~
The ionic conductivity was measured in the same manner as in 10 and is shown in Table 3.

[Table] Examples 21 to 26 A predetermined amount of LiPF ₆ was added to the polymers of Experimental Examples 11, 13, 15, and 16 to 18, heated to about 200°C under nitrogen, kneaded, and melted on a Teflon plate. I casted it. After cooling, the ionic conductivity was measured in the same manner as in Experimental Examples 1 to 10 and is shown in Table 4.

【table】

[Table] Examples 27 to 32 The hybrids of Examples 21 to 26 were cooled as they were without being cast to form an amorphous solid. Cut this into thin pieces and apply a pressure of about 5 kg/cm ² to
A film was formed by heating to ℃, and the ionic conductivity was measured in Example 1~
Measurements were made in the same manner as in 10 and shown in Table 5.

Claims (1)

[Claims] 1. General formula [Here, R is H or CH ₃ , R' is an alkyl group having 1 to 6 carbon atoms, n is an integer of 5 to 20, x
is 100 to 50%, x+y=100%, molecular weight is 10,000 to 500,000] and LiClO ₄ , LiBF ₄ and
Inorganic lithium salt selected from LiPF ₆ and 99/
A hybrid ion conductor made by mixing in a weight ratio of 1 to 50/50.