FLUOROPOLYMER HYBRID COMPOSITE

Abstract

The present invention pertains to a fluoropolymer hybrid organic/inorganic composite, to a film comprising said fluoropolymer hybrid organic/inorganic composite and to uses of said film in various applications, especially in electrochemical and in photo-electrochemical applications.

Claims

1. A process for manufacturing a fluoropolymer hybrid organic/inorganic composite (FH), said process comprising: (i) providing a pre-composite (FP) by processing in molten phase: a pre-gel compound (MP) obtainable by at least partial hydrolysis and/or polycondensation, in the presence of a liquid medium, of at least one metal compound (M) of formula (I):
X.sub.4-mM(OY).sub.m(I) wherein M is a metal selected from the group consisting of Si, Ti and Zr, X and Y, equal to or different from each other and at each occurrence, are selected from hydrocarbon groups, optionally comprising one or more functional groups, and m is an integer comprised between 1 and 4, and at least one polymer (FF), wherein polymer (FF) is at least one functional fluoropolymer comprising at least one hydroxyl group; (ii) providing a composition by compounding the pre-composite (FP) provided in step (i) with: at least one poly(alkylene oxide) (PAO) of formula (II):
HO(CH.sub.2CHR.sub.AO).sub.nR.sub.B(II) wherein R.sub.A is a hydrogen atom or a C.sub.1-C.sub.5 alkyl group, R.sub.B is a hydrogen atom or a CH.sub.3 alkyl group and n is an integer comprised between 2000 and 40000, at least one metal salt (M), optionally, at least one fluoropolymer [polymer (F)], equal to or different from the polymer (FF), and optionally, one or more inorganic fillers; and (iii) processing in molten phase the composition provided in step (ii).

2. The process according to claim 1, wherein the polymer (FF) comprises at least 0.01% by moles of recurring units derived from at least one monomer (OH).

3. The process according to claim 1, wherein the polymer (FF) comprises at most 20% by moles of recurring units derived from at least one monomer (OH).

4. The process according to claim 2, wherein the monomer (OH) is selected from the group consisting of (meth)acrylic monomers of formula (III) and vinylether monomers of formula (IV): ##STR00011## wherein each of R.sub.1, R.sub.2 and R.sub.3, equal to or different from each other, is independently a hydrogen atom or a C.sub.1-C.sub.3 hydrocarbon group, and R.sub.OH is a C.sub.1-C.sub.5 hydrocarbon group comprising at least one hydroxyl group.

5. The process according to claim 1, wherein the compound (MP) is in the form of a liquid composition comprising one or more domains of formula [O-MX.sub.4-m*(OY).sub.m*-2]O, wherein M is a metal selected from the group consisting of Si, Ti and Zr, X and Y, equal to or different from each other and at each occurrence, are hydrocarbon groups, optionally comprising one or more functional groups, and m* is an integer comprised between 2 and 4.

6. The process according to claim 1, wherein the pre-composite (FP) comprises one or more domains of formula [O-M(OZ.sub.1)(OZ.sub.2)]O, wherein M is a metal selected from the group consisting of Si, Ti and Zr, and Z.sub.1 and Z.sub.2, equal to or different from each other, are hydrocarbon groups, optionally comprising one or more functional groups, at least one of said Z.sub.1 and Z.sub.2 being a hydrocarbon group comprising recurring units derived from at least one monomer (OH).

7. A fluoropolymer hybrid organic/inorganic composite (FH) obtainable by the process according to claim 1.

8. The composite (FH) according to claim 7, said composite (FH) comprising: at least one pre-composite (FP), at least one poly(alkylene oxide) (PAO) of formula (II):
HO(CH.sub.2CHR.sub.AO).sub.nR.sub.B(II) wherein R.sub.A is a hydrogen atom or a C.sub.1-C.sub.5 alkyl group, R.sub.B is a hydrogen atom or a CH.sub.3 alkyl group and n is an integer comprised between 2000 and 40000, at least one metal salt (M), optionally, at least one fluoropolymer [polymer (F)], equal to or different from the polymer (FF), and optionally, one or more inorganic fillers.

9. A process for manufacturing a film, said process comprising processing in molten phase at least one composite (FH) according to claim 8.

10. A film comprising at least one composite (FH) according to claim 8.

11. The film according to claim 10, said film being a dense film.

12. An electrochemical device or a photo-electrochemical device comprising at least one film according to claim 10.

13. The device of claim 12, wherein the film is used as a separator for the devices.

14. The process according to claim 1, wherein n is an integer comprised between 11500 and 30000.

15. The process according to claim 2, wherein the polymer (FF) comprises at least 0.05% by moles of recurring units derived from at least one monomer (OH).

16. The process according to claim 15, wherein the polymer (FF) comprises at least 0.1% by moles of recurring units derived from at least one monomer (OH).

17. The process according to claim 3, wherein the polymer (FF) comprises at most 15% by moles of recurring units derived from at least one monomer (OH).

18. The process according to claim 17, wherein the polymer (FF) comprises at most 10% by moles of recurring units derived from at least one monomer (OH).

19. The process according to claim 1, wherein the polymer (FF) comprises at least 0.05% by moles and at most 15% by moles of recurring units derived from at least one monomer (OH).

20. The composite (FH) according to claim 8, wherein n is an integer comprised between 11500 and 30000.

Description

EXAMPLE 1

[0178] The pre-composite (FP) was manufactured at a rate for the polymer (FF-1) of 0.450 Kg/h and a rate for the pre-gel compound of 0.833 Kg/h. The nominal composition obtained was: FF-1/SiO.sub.2: 75/25% wt.

[0179] Composite (FH): pre-composite (FP) 0.525 Kg/h, PAO 0.875 Kg/h and LiTFSI aqueous solution 0.4375 Kg/h.

[0180] The final composition of the composite (FH) was: 50% by weight of PAO, 22.5% by weight of polymer (FF-1), 20% by weight of LiTFSI and 7.5% by weight of SiO.sub.2.

[0181] The ionic conductivity of this material was measured on a compression molded film of about 100 m. The results are set forth in Table 3.

EXAMPLE 2

[0182] The same procedure as detailed under Example 1 was followed but using a polymer (FF-2).

[0183] The results are set forth in Table 3.

EXAMPLE 3

[0184] The same procedure as detailed under Example 1 was followed but using a pre-composite manufactured at a rate for the polymer (FF-1) of 0.525 Kg/h and a rate for the pre-gel compound of 0.417 Kg/h. The nominal composition obtained was: FF-1/SiO.sub.2: 87.5/12.5% wt.

[0185] The final composition of the composite was: 50% by weight of PAO, 26.25% by weight of polymer (FF-1), 20% by weight of LiTFSI and 3.75% by weight of SiO.sub.2.

[0186] The results are set forth in Table 3.

EXAMPLE 4

[0187] The same procedure as detailed under Example 3 was followed but using a pre-composite (FP) obtained from the polymer (FF-2).

[0188] This material was successfully extruded to a film thickness of 30 m in absence of defects.

[0189] The results are set forth in Table 3.

COMPARATIVE EXAMPLE 1

[0190] The polymer (1), PAO and the LiTFSI were compounded in the following ratio: 50% by weight of PAO+30% by weight of polymer (1) and 20% by weight of LiTFSI according to the general procedure for the manufacture of the composite but without using a pre-gel compound.

[0191] The ionic conductivity of this material was measured on an extruded film of about 150 m. The results are set forth in Table 3.

TABLE-US-00003 TABLE 3 Ionic conductivity [S/cm] Run 40 C. 55 C. 70 C. 80 C. Ex. 1 110 260 430 Ex. 2 64 340 900 1500 Ex. 3 90 630 500 1000 C. Ex. 1 42 180 374 574

[0192] In view of the above, it has been surprisingly found that the process of the invention enables easily obtaining the composite (FH) leading to films with outstanding ionic conductivity in comparison to the films of the state of the art.

[0193] Also, it has been surprisingly found the composite (FH) of the invention can be easily processed into film separators, typically by casting extrusion. The process of the invention thus successfully enables manufacturing separators for both electrochemical devices and photo-electrochemical devices.