FR3144135A1 - Process for preparing a polymer and solid polymer electrolyte incorporating such a polymer - Google Patents

Abstract

The present invention relates to a process for manufacturing a polymer comprising the following steps:i) bringing into contact: a) at least one styrenic monomer comprising at least one polyether; and b) a free radical initiator;ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C.

Description

Process for preparing a polymer and solid polymer electrolyte incorporating such a polymer

The present invention relates to the field of polymers and solid electrolytes incorporating a polymer.

More particularly, the present invention relates to a process for manufacturing a polymer, a polymer capable of being obtained by said manufacturing process, as well as a solid polymer electrolyte comprising such a polymer and at least one electrolyte salt. The invention also relates to a method of manufacturing said solid polymer electrolyte, to an all-solid-state battery cell comprising said solid polymer electrolyte, as well as an all-solid-state battery comprising said cell.

Previous techniques

A polymer is obtained by assembling a plurality of monomer units repeating throughout the polymer chain.

Certain large molecules, called “macromonomers”, have a terminal group allowing them to form a monomer unit and be incorporated into a polymer chain.

PEGylated styrene, a styrenic molecule comprising a poly(ethylene oxide) (PEG) group, is an example of a well-known macromonomer, particularly for applications in the field of biology.

Generally, it is difficult to polymerize macromonomers, given their large size which disrupts the propagation of polymerization.

Conventionally, in order to polymerize macromonomers, reversible polymerization methods, called controlled or living, such as radical polymerization by atom transfer (ATRP), radical polymerization controlled by reversible chain transfer by addition-fragmentation (RAFT) or again polymerization using nitroxide (NMP), are preferred to methods such as polymerization by free radicals called “free-radical polymerization” (FRP) in English.

Indeed, controlled polymerization methods have several advantages including the precision of the molecular weight of the resulting polymer, and the capacity for block copolymerization.

However, they generally require high temperatures, a transition metal catalyst or exotic radical initiator, inert gas conditions, and long reaction times.

Additionally, the accessibility of the polymer during polymerization remains limited and, therefore, so does the conversion rate of the final polymer.

There is therefore a need to develop a new polymerization process, in particular for the manufacture of polymer obtained from a macromonomer unit, making it possible to overcome the above disadvantages.

The subject of the invention is therefore a process for manufacturing a polymer comprising the following steps:

i) put in contact:

a) at least one styrenic monomer comprising at least one polyether; And

b) a free radical initiator;

ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C.

Surprisingly, it has been found that the process for manufacturing a polymer according to the invention based on free radical polymerization is particularly advantageous for polymers obtained from macromonomers and allows polymerization without requiring a catalyst based on transition metal or an exotic radical initiator, nor inert gas conditions, at low temperature, and leading to an improved conversion rate.

In addition, the process for manufacturing a polymer according to the invention is carried out without solvent, so that mass manufacturing can be easily carried out.

In addition, the process for manufacturing a polymer according to the invention makes it possible to obtain a polymer insoluble in many common solvents (water, DMSO, DCM, DMF, anisole, NMP, ethyl acetate, ethanol, THF etc.), which is particularly advantageous for applications in various fields such as the field of solid polymer electrolytes for all-solid-state batteries, but also in a membrane of a gas separation device, a membrane of a device carbon storage, or even a membrane of a drug delivery device.

The invention also relates to a process for manufacturing a solid polymer electrolyte comprising the following steps:

i) put in contact:

a) at least one styrenic monomer comprising at least one polyether; And

b) a free radical initiator;

ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C;

iii) recover the polymer obtained;

at least one electrolyte salt being added during step i) and/or step iii).

The invention also relates to a polymer capable of being obtained by a manufacturing process according to the invention, as well as a solid polymer electrolyte comprising at least one electrolyte salt and a polymer according to the invention.

Other objects of the invention are an all-solid-state battery cell comprising the solid polymer electrolyte according to the invention, as well as an all-solid-state battery comprising the cell according to the invention.

Other characteristics, aspects, objects and advantages will emerge from the description which follows and from the following examples, given for purely illustrative purposes.

It is specified that the expression “from… to…” used in this description of the invention must be understood as including each of the limits mentioned.

In this description, the expression “at least one” used must be considered equivalent to the expression “one or more”.

As indicated above, the process for manufacturing the polymer according to the invention comprises a step i) of bringing into contact:

a) at least one styrenic monomer comprising at least one polyether; And

b) a free radical initiator.

In step ii), the mixture comprising a) and b) obtained is then heated to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C.

For the purposes of the present invention, “styrenic monomer” means a monomer having at least the chemical structure of styrene.

Advantageously, the polyether can be chosen from: poly(ethylene oxide), poly(propylene oxide), polyoxymethylene, and their copolymers.

In one embodiment, the styrenic monomer may comprise a copolymer group comprising at least two polyethers of different nature.

Advantageously, the styrenic monomer may comprise a molar mass by weight or molecular weight ranging from 150 to 2000 g/mol, preferably from 200 to 700 g/mol, more preferably from 300 to 450 g/mol.

In this description, the molar mass is considered by weight unless otherwise indicated.

In one embodiment, the styrenic monomer may comprise at least one unit of formula (I):

where m goes from 3 to 45. Preferably, m goes from 5 to 14.

In another embodiment, the styrenic monomer may, for example, comprise a poly(ethylene oxide)–poly(propylene oxide) block copolymer group.

Preferably, in step i), the mixture of a) and b) may comprise from 1 to 10 mol% of free radical initiator relative to the number of moles of styrenic monomers.

Preferably, the free radical initiator is an azo initiator.

By azo initiator is meant in the present invention a free radical initiator comprising an azo group in its molecular structure.

Advantageously, the azo free radical initiator can be chosen from: azobisisobutyronitrile (AIBN), 1,1'-Azobis(cyclohexanecarbonitrile), 2,2'-Azobis(2-methylbutyronitrile), 4,4'-Azobis(4- cyanovaleric acid), 2,2'-Azobis(2,4-dimethylvaleronitrile) or a mixture thereof.

In one embodiment, the polymer manufacturing process consists of the following steps:

i) put in contact:

a) at least one styrenic monomer comprising at least one polyether; And

b) a free radical initiator;

ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C.

Everything that has been described above concerning the polymer in the context of the manufacturing process of said polymer is valid for the polymer capable of being obtained by the manufacturing process according to the invention.

As indicated above, the solid polymer electrolyte according to the invention comprises a) at least one polymer as described above, and b) at least one electrolyte salt.

Advantageously, the electrolyte salt can be chosen from alkaline earth metal salts, alkali metal salts and their mixtures, preferably from alkali metal salts, more preferably from sodium salts, lithium salts and their mixtures. , even more preferably among lithium salts.

Preferably, the electrolyte salt is chosen from LiPF ₆ , LiFSI, LiTFSI, LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiI, LiN(CF ₃ SO ₂ ) ₂ , LiCF ₃ SO ₃ , LiN(CF ₃ CF ₂ SO ₂ ) ₂ , LiCH ₃ SO ₃ , LiN(CF ₃ SO ₂ )(CF ₂ HSO ₂ ), LiN(RFSO ₂ ) ₂ , LiC(RFSO ₂ ) ₃ , RF being a group chosen from a fluorine atom and a perfluoroalkyl group comprising from one to eight carbon atoms.

The present invention also relates to a process for preparing a solid polymer electrolyte.

As mentioned before, said preparation process comprises the following steps:

i) put in contact:

a) at least one styrenic monomer comprising at least one polyether; And

b) a free radical initiator;

ii) heating the mixture comprising a) and b) to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C;

iii) recover the polymer obtained;

at least one electrolyte salt being added during step i) and/or step iii).

Preferably, the free radical initiator is an azo initiator.

Advantageously, the azo free radical initiator can be chosen from: azobisisobutyronitrile (AIBN), 1,1'-Azobis(cyclohexanecarbonitrile), 2,2'-Azobis(2-methylbutyronitrile), 4,4'-Azobis(4- cyanovaleric acid), 2,2'-Azobis(2,4-dimethylvaleronitrile) or a mixture thereof.

Everything that has been described above concerning the polymer and the process for manufacturing said polymer is valid for the solid polymer electrolyte and the process for manufacturing a solid polymer electrolyte according to the invention.

Preferably, step ii) of heating takes place for a period ranging from 1 hour to 15 hours, preferably from 3 to 10 hours, more preferably from 4 to 8 hours.

The electrolyte salt can be added either during step (i) of bringing a) and b into contact, or during step (iii) during recovery of the polymer obtained, or during step (i) and also step (iii).

Preferably, the electrolyte salt is added during contacting step i).

In addition, step i) of contacting can take place in the presence of a solvent, such as for example tetrahydrofuran (THF) or dichloromethane.

Advantageously, the styrenic monomer comprises a molar mass ranging from 150 to 2000 g/mol, preferably from 200 to 700 g/mol, more preferably from 300 to 450 g/mol.

Preferably, 1 to 10% by moles of free radical initiator relative to the number of moles of styrenic monomers is brought into contact with said styrenic monomer.

In one embodiment, said styrenic monomer comprises at least one unit of formula (I):

where m goes from 3 to 45. Preferably, m goes from 5 to 14.

Advantageously, said electrolyte salt can be chosen from alkaline earth metal salts, alkali metal salts and their mixtures, preferably from alkali metal salts, more preferably from sodium salts, lithium salts and their mixtures. , even more preferably among lithium salts.

Preferably, said electrolyte salt is chosen from LiPF₆, LiFSI, LiTFSI, LiClO₄, LiAsF₆, LiBF₄, LiI, LiCF₃SO₃, LiN(CF₃CF₂SO₂)₂, LiCH₃SO₃, LiN(CF₃SO₂)(CF₂H.S.O.₂), LiN(RFSO₂)₂, LiC(RFSO₂)₃, RF being a group chosen from a fluorine atom and a perfluoroalkyl group comprising from one to eight carbon atoms.

The invention also relates to an all-solid-state battery cell comprising at least one solid polymer electrolyte according to the invention as defined above.

Another object of the present invention is an all-solid-state battery comprising at least one cell as defined above.

The present invention is illustrated in a non-limiting manner by the following examples.

The polymer according to the invention is therefore a particularly suitable candidate for an application, according to one example, as a polymer for a solid polymer electrolyte within an all-solid battery.

Another object of the invention is also a membrane comprising at least one polymer according to the invention as described previously.

Advantageously, said membrane can be a membrane of a gas separation device, a membrane of a carbon storage device, or even a membrane of a drug administration device.

Examples

Example 1: preparation of a polymer by controlled radical polymerization

In a 25 mL vial equipped with a stir bar, 0.0278 g, i.e. 7.3x10-5 mol and 1 Eq. of alkoxyamine sold by Arkema under the trade name BlocBuilder® and of the following formula:

The vial is closed with a rubber septum, degassed to remove oxygen, and then 2 mL of degassed anisole is added to the vial using a degassed syringe.

1.9862 g, or 3.6x10-3 mol, 50 Eq. 4-vinylbenzyl methoxynona(ethylene glycol)ether (otherwise known as PEGylated styrene) is added to the solution under stirring which is then purged for 10 min in order to remove any residual oxygen.

The bottle was then placed in an oil bath preheated to 120°C.

The kinetics of the polymerization reaction were monitored at regular intervals by Nuclear Magnetic Resonance (NMR) spectroscopy using an argon exchange syringe to remove samples from the reaction medium.

After a polymerization time of 360 min, the vial was removed from the oil bath and the mixture was allowed to cool to room temperature.

The anisole was then removed using a rotary evaporator and the remaining polymer obtained was purified by dialysis with water using a membrane having a cut-off molecular weight between 6000 to 8000 g/mol ^-1 .

Using NMR spectroscopy, it was found that the final conversion rate of the monomer was 0.92.

The purified polymer obtained was characterized by size exclusion chromatography (SEC). Its number molar mass (Mn) is 19500 g.mol ^-1 .

It was observed that the resulting polymer is soluble in water, dimethyl sulfoxide (DMSO), and organic solvents such as tetrahydrofuran (THF).

Example 2: preparation of a polymer according to the invention

1) Formation of a styrenic monomer comprising a poly(ethylene oxide):

1 equivalent (Eq.) of poly(ethylene glycol) monomethyl ether with a molar mass equal to 350g/mol was dissolved in dry THF, then 1.5 Eq of NaH was then added slowly under an argon atmosphere.

The mixture was stirred for 3 hours until its color became intense yellow.

1.5 Eq. of 4-vinylbenzyl chloride was then added dropwise while stirring the mixture vigorously for 24 hours.

The crude product obtained was purified several times by several washings with water and n-hexane. The aqueous solution was collected and then the water it contained was removed using a rotary evaporator.

The resulting liquid was dissolved in dichloromethane (DCM) and then dried with sodium sulfate.

After removing the DCM, a yellow liquid including the monomer 4-vinylbenzyl methoxynona(ethylene glycol) ether was obtained and its purity was determined by NMR spectroscopy.

2) Formation of the polymer by free radical polymerization according to the invention

35 mg of thermal initiator azobisisobutyronitrile (AIBN) were dissolved in 1 g, or 10 mol%, of 4-vinylbenzyl methoxynona(ethylene glycol) ether monomer previously prepared in step 1), including the molar mass of the chain poly(ethylene oxide) is 350 g/mol.

The mixture was then put in an oven at 65°C for 6 hours.

A yellow-colored and particularly flexible polymer was obtained.

Surprisingly, this polymer was found to be insoluble in many common solvents such as water, DMSO, DCM, DMF, anisole, NMP, ethyl acetate, ethanol, and THF.

It has been observed that in the presence of such solvents, the polymer obtained swells by absorbing part of the solvent.

The polymer according to the invention is therefore a particularly suitable candidate for an application, according to one example, as a polymer for a solid polymer electrolyte within an all-solid-state battery.

Additionally, such a polymer can be used to retain solvent.

Example 3: preparation of a solid polymer electrolyte according to the invention

35 mg of thermal initiator azobisisobutyronitrile (AIBN), LiTFSI and 1g of 4-vinylbenzyl methoxynona(ethylene glycol) ether monomer as previously prepared in step 1) of Example 2, including the molar mass of the poly chain (ethylene oxide) is 350 g/mol, were dissolved in THF solvent.

THF was used to improve the homogeneity of the solution.

The resulting solution was poured onto a PTFE Teflon® sheet and then stored until the solvent evaporated.

The mixture was then put in an oven at 65°C for 6 hours.

Claims (16)

Process for manufacturing a polymer comprising the following steps:
i) put in contact:
a) at least one styrenic monomer comprising at least one polyether; And
b) a free radical initiator;
ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C. Process according to claim 1, in which the polyether is chosen from: poly(ethylene oxide), poly(propylene oxide), polyoxymethylene and their copolymers. Method according to one of claims 1 or 2, step ii) takes place for a period ranging from 1 hour to 15 hours, preferably from 3 to 10 hours, more preferably from 4 to 8 hours. Process according to any one of Claims 1 to 3, in which said styrenic monomer comprises a molar mass by weight ranging from 150 to 2000 g/mol, preferably from 200 to 700 g/mol, more preferably from 300 to 450 g/mol. mol. Process according to any one of claims 1 to 4, in which the styrenic monomer comprises at least one unit of formula (I) following:

where m ranges from 3 to 45, preferably from 5 to 14. Process according to any one of claims 1 to 5, in which the free radical initiator is an azo initiator, preferably chosen from: azobisisobutyronitrile (AIBN), 1,1′-Azobis(cyclohexanecarbonitrile), 2,2′- Azobis(2-methylbutyronitrile), 4,4'-Azobis(4-cyanovaleric acid), 2,2'-Azobis(2,4-dimethylvaleronitrile) or a mixture thereof. Polymer capable of being obtained by a manufacturing process according to any one of claims 1 to 6. Solid polymer electrolyte comprising a polymer as defined in claim 7, and at least one electrolyte salt. Electrolyte according to claim 8, in which said electrolyte salt is chosen from alkaline earth metal salts, alkali metal salts and mixtures thereof, preferably from alkali metal salts, more preferably from sodium salts, salts of lithium and their mixtures, even more preferably among lithium salts. Electrolyte according to claim 8 or 9, in which said electrolyte salt is chosen from LiPF ₆ , LiFSI, LiTFSI, LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiI, LiCF ₃ SO ₃ , LiN(CF ₃ CF ₂ SO ₂ ) ₂ , LiCH ₃ SO ₃ , LiN(CF ₃ SO ₂ )(CF ₂ HSO ₂ ), LiN(RFSO ₂ ) ₂ , LiC(RFSO ₂ ) ₃ , RF being a group chosen from a fluorine atom and a perfluoroalkyl group comprising a with eight carbon atoms. Process for manufacturing a solid polymer electrolyte comprising the following steps:
i) put in contact:
a) at least one styrenic monomer comprising at least one polyether; And
b) a free radical initiator;
ii) heating the mixture to a temperature ranging from 40 to 110°C, preferably ranging from 60 to 90°C, more preferably ranging from 75 to 85°C;
iii) recover the polymer obtained;
at least one electrolyte salt being added during step i) and/or step iii). Method according to claim 11, in which step ii) takes place for a period ranging from 1 hour to 15 hours, preferably from 3 to 10 hours, more preferably from 4 to 8 hours. Process according to claim 11 or 12, in which said styrenic monomer comprises a molar mass ranging from 150 to 2000 g/mol, preferably from 200 to 700 g/mol, more preferably from 300 to 450 g/mol. Process according to any one of claims 11 to 13, in which the free radical initiator is an azo initiator, preferably chosen from: azobisisobutyronitrile (AIBN), 1,1′-Azobis(cyclohexanecarbonitrile), 2,2′- Azobis(2-methylbutyronitrile), 4,4'-Azobis(4-cyanovaleric acid), 2,2'-Azobis(2,4-dimethylvaleronitrile) or a mixture thereof All-solid-state battery cell comprising at least one solid polymer electrolyte as defined in any one of claims 8 to 10. All-solid-state battery comprising at least one cell as defined in claim 15.