Polymer blend for electrode binder

Abstract

The present invention relates to an electrode binder comprising a fluorinated polymer A1 comprising monomer units derived from a monomer M1 being vinylidene fluoride and an acrylic polymer A2; said fluorinated polymer A1 also comprises monomer units derived from a monomer M3 bearing an acid functional group and said acrylic polymer A2 also comprises an anhydride functional group; or said fluorinated polymer A1 also comprises an anhydride functional group and said acrylic polymer A2 comprises monomer units derived from a monomer M3 bearing an acid functional group.

Description

[0001] polymers for electrode binder

[0002] technical field

[0003] The present invention relates generally to the field of electrical energy storage in all-solid-state batteries, particularly in secondary Li-ion batteries. More specifically, the present invention relates to an electrode binder.

[0004] Technological background of the invention

[0005] A secondary lithium battery can be used as a power source for a variety of electronic devices, ranging from cell phones, laptops, and small household appliances to vehicles and high-capacity energy storage devices, and the demand for secondary lithium batteries continues to grow. For the widespread adoption of electric vehicles, reducing battery manufacturing costs is paramount, and one option under consideration is the use of a low-cost, cobalt-free active material. Furthermore, increasing the energy density of electric vehicle batteries remains a major challenge for the mass adoption of this technology. Increasing electrode thickness and reducing the particle size of active material would help achieve these cost and energy density objectives.

[0006] Increasing the thickness of the ink requires improved electrode / collector adhesion, and using active materials with lower cobalt content necessitates improved ink stability over time. There remains a need for electrode binders with enhanced adhesion while maintaining excellent stability.

[0007] Summary of the invention

[0008] According to a first aspect, the present invention provides an electrode binder comprising a fluorinated polymer Al including monomeric units derived from the monomer M1, vinylidene fluoride, and an acrylic polymer A2 including monomeric units derived from the monomer M2 of formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 , R 2 and R 3are independently selected from the group consisting of H and C1-C5 alkyl groups; R is selected from the group consisting of H and Ci-Cis alkyl groups optionally substituted with one or more -OH groups; characterized in that said fluorinated polymer Al also comprises monomeric units derived from monomer M3 bearing an acid functional group and said acrylic polymer A2 also comprises at least one anhydride functional group; or said fluorinated polymer Al also comprises at least one anhydride functional group and said acrylic polymer A2 also comprises monomeric units derived from monomer M3 bearing an acid functional group. Surprisingly, the applicant discovered that a combination of at least two polymers, each bearing a specific chemical function, i.e.Anhydride for one and acid for the other, significantly improved adhesion to the current collector and also ink stability. In a preferred embodiment, the monomeric units derived from monomer M3 have the formula R. 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 , R 5 and R 6 are independently selected from the group consisting of H and C1-C5 alkyl;

[0009] R 7 is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and Ci-Ci8alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ;

[0010] R 8' is selected from the group consisting of Ci-C5alkyl and C6-Ci2aryl substituted by one or more CO2H, SO3H functional groups;

[0011] X 3 is selected from the group consisting of - [-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-] w i- and an alkyl hydrocarbon group Ci-Cio optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 23 , R 24 , R 25 , R 26 are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5alkyl; p is 0 or 1.

[0012] According to a preferred embodiment, said anhydride function is introduced into the Al or A2 polymer either by monomeric units from a monomer M4 have formula (I), (II) or (III)

[0013] [Chem 1]

[0014]

[0015] [Chem 2]

[0016]

[0017] [Chem 3]

[0018]

[0019] in which the R substituents 9 , R 10 , R 11 , R 12 , R 15 , R 16 , R 17 , R 20 , R 21 and R 22 are independently selected from the group consisting of H, Ci-C5alkyl; R 13 , R 14 , R 18 and R 19are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-Cis alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 12; or a mixture of these; either said polymer Al or A2 comprises the motif M5 of formula X1-C(O)-OC(O)-X2 in which XI and X2 independently represent a polymer chain of said fluorinated polymer Al or of the acrylic polymer A2.

[0020] According to a preferred embodiment, the fluorinated polymer Al comprises monomeric units derived from a monomer Ml' selected from the group consisting of vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes, tetrafluoropropenes, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes, perfluoroalkylvinyl ethers, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene and ethylene or a mixture thereof.

[0021] According to a preferred embodiment, said acrylic polymer A2 comprising monomeric units derived from monomer M2 selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-dodecyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, n-octyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethyl (meth)acrylate, and mixtures thereof.

[0022] According to a preferred embodiment, the mass ratio A1 / A2 varies from 95 / 5 to 5 / 95.

[0023] According to another aspect, the present invention provides an electrode composition comprising at least one active material, at least one conductive agent and said binder according to the present invention.

[0024] According to a preferred embodiment, said active material is selected from the group consisting of LiCoO2, Li(Ni, Co, Al)O2, Li(i +X )Neither a MnbCo c O2, where x represents a real number of 0 or more, a = 0.8, 0.6, 0.5, or 1 / 3, b = 0.1, 0.2, 0.3, or 1 / 3, c = 0.1, 0.2, or 1 / 3, LiNiO2, LiMn2O4, LiCoMnC, Li3NiMn3O3, Li3Fe2(PO4)3, Li3V2(PO4)3, a LiMn spinel substituted by a different element having a composition represented by Lii+xMn 2.x .yMyO , M representing at least one metal chosen from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate Li x TiO y with x and y independently representing a real number between 0 and 2, and a metal and lithium phosphate having a composition represented by LiMPO4, M representing Fe, Mn, Co, or Ni.

[0025] According to a preferred embodiment, said conducting agent is selected from the group consisting of carbon blacks, such as acetylene black, Ketjen black; carbon fibers, such as a carbon nanotube, a carbon nanofiber, a carbon fiber by vapor phase growth; metal powders such as SUS powder, and aluminum powder; and mixtures thereof. In another aspect, the present invention provides a positive electrode comprising a metallic collector, at least one face of which is coated with said electrode composition according to the present invention.

[0026] According to another aspect, the present invention provides a lithium ion battery comprising a negative electrode, a positive electrode according to the present invention and a separator between said positive electrode and said negative electrode.

[0027] According to another aspect, the present invention provides an electrochemical device comprising a negative electrode, a positive electrode according to the present invention and an electrolyte comprising lithium.

[0028] Detailed description of the invention

[0029] According to a first aspect of the present invention, an electrode binder is provided. This binder, through a specific combination of chemical functions in its constituents, improves the adhesion properties and stability of the electrode composition. Specifically, the basic functions of the oxide-type active materials react with the anhydride-type functional groups present in the fluorinated polymer Al or the acrylic polymer A2. This reaction is catalyzed by the acidic functions of the other polymer. This functionalization of the active material significantly improves the adhesion and cohesion of the cathode.

[0030] In particular, said electrode binder comprises a mixture of a fluoropolymer Al and an acrylic polymer A2. At least one of the polymers Al or A2 comprises anhydride-type functional groups. At least one of the polymers Al or A2 comprises CO2H, SO3H acid-type functional groups. Thus, said fluoropolymer Al comprises anhydride-type functional groups and the acrylic polymer A2 comprises CO2H, SO3H acid-type functional groups; or said acrylic polymer A2 comprises anhydride-type functional groups and the fluoropolymer Al comprises CO2H, SO3H acid-type functional groups. In an alternative embodiment, said polymers Al and A2 carry both anhydride-type and CO2H, SO3H acid-type functional groups.

[0031] According to a preferred embodiment, said fluorinated polymer Al comprises monomeric units derived from a monomer M3 bearing an acid functional group and said acrylic polymer A2 also comprises at least one anhydride functional group.

[0032] According to another embodiment, said fluorinated polymer Al also comprises at least one anhydride functional group and said acrylic polymer A2 comprises monomeric units derived from a monomer M3 bearing an acid functional group.

[0033] Monomeric units derived from an M3 monomer

[0034] According to a preferred embodiment, the monomer M3 has the formula R 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 , R 5 and R 6 are independently selected from the group consisting of H and C1-C5 alkyl; R 7is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and Ci-Ci8 alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C5alkyl and C6-Ci2aryl substituted by one or more CO2H, SO3H functional groups; X 3 is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-] w i- and an alkyl hydrocarbon group Ci-Cio optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 23 , R 24 , R 25 , R 26are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5alkyl; p is 0 or 1.

[0035] Advantageously, the monomer M3 has the formula R 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 , R 5 and R 6 are independently selected from the group consisting of H and Ci-C5alkyl; R 7 is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and C1-C15 alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C5alkyl and C6-Ci2aryl substituted by one or more CO2H, SO3H functional groups; X 3is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-] W I- and an alkyl hydrocarbon group Ci-Cio optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 23 , R 24 , R 25 , R 26 are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5alkyl; p is 0 or 1.

[0036] Preferably, the monomer M3 has the formula R 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 , R 5 and R 6 are independently selected from the group consisting of H and Ci-C5alkyl; R 7 is selected from the group consisting of -OR 8with R 8 selected from the group consisting of H and Ci-Cio alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C5alkyl and C6aryl substituted by one or more CO2H, SO3H functional groups; X 3 is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-] w i- and a Ci-C5alkyl hydrocarbon group optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 10, in particular from 1 to 5; R 23 , R 24 , R 25 , R 26 are independently of each other, independently for each unit wl, selected from the group consisting of H and C C3alkyl; p is 0 or 1.

[0037] More preferably, the monomer M3 has the formula R4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 and R 5 are H; R 6 is selected from the group consisting of H and Ci-C5alkyl; R 7 is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and Ci-C8 alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C3alkyl and C6aryl substituted by one or more CO2H, SO3H functional groups; X 3 is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-]wi- and a Ci-C5alkyl hydrocarbon group optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 5; R 23 , R24 , R 25 , R 26 are independently of each other, independently for each unit wl, selected from the group consisting of H and C3-C3alkyl; p is 0 or 1.

[0038] In particular, the monomer M3 has the formula R 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 and R 5 are H; R 6 is selected from the group consisting of H and Ci-C3alkyl; R 7 is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and Ci-C5 alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C3alkyl and C6aryl substituted by one or more CO2H, SO3H functional groups; X 3is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-]wi- and a Ci-C5alkyl hydrocarbon group optionally bearing one or more -CO2H group(s); with wl being an integer from 1 to 5; R 23 , R 24 , R 25 , R 26 are independently of each other, independently for each unit wl, selected from the group consisting of H and C3-C3alkyl; p is 0 or 1.

[0039] More specifically, the M3 monomer has the formula R 4 R 5 C=C(R 6 )(HORN 7 ) in which the R substituents 4 and R 5 are H; R 6 is selected from the group consisting of H and Ci-C3alkyl; R 7 is selected from the group consisting of -OR 8 with R 8selected from the group consisting of H and Ci-C5 alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8 ' is selected from the group consisting of Ci-C3alkyl and C6aryl substituted by one or more CO2H, SO3H functional groups.

[0040] Preferably, the monomer M3 is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, the monomers of formula CH2=CH(CO2CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH(CH3)CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)-C6H4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H).

[0041] Monomeric units derived from an M4 monomer

[0042] According to a preferred embodiment, the monomer M4 has formula (I), (II) or (III)

[0043] [Chem 1]

[0044] O

[0045] O

[0046]

[0047] (I)[Chem 2]

[0048]

[0049] (H)

[0050] [Chem 3]

[0051]

[0052] in which the R substituents 9 , R 10 , R 11 , R 12 , R 15 , R 16 , R 17 , R 20 , R 21 and R 22 are independently selected from the group consisting of H, C1-C5 alkyl; R 13 , R 14 , R 18 and R 19are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 12.

[0053] Advantageously, the monomer M4 has formula (I), (II) or (III)

[0054] [Chem 1]

[0055] O

[0056] O

[0057]

[0058] (I)

[0059] [Chem 2]

[0060]

[0061] [Chem 3]

[0062]

[0063] in which the R substituents 9 , R 10 , R 11 , R 12 , R 15 , R 16 , R 17 , R 20 , R 21 and R 22are independently selected from the group consisting of H, Ci-C5alkyl; R 13 , R 14 , R 18 and R 19 are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-Ci5 alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 10.

[0064] Preferably, the monomer M4 is of formula (I), (II) or (III)

[0065] [Chem 1]

[0066] O

[0067] O

[0068] (I)

[0069] (H)

[0070] [Chem 3]

[0071]

[0072] in which the R substituents 9 , R 10 , R 11 , R 12 , R 15 , R 16 , R 17 , R 20 , R21 and R 22 are independently selected from the group consisting of H, C1-C5 alkyl; R 13 , R 14 , R 18 and R 19 are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-Cio alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 10. More preferably, the monomer M4 is of formula (I), (II) or (III)

[0073] [Chem 1]

[0074] O

[0075] O

[0076] (I)

[0077] (he)

[0078] [Chem 3]

[0079]

[0080] in which the R substituents 15 , R 16 , R 21 and R 22 are H; R 9 , R 10 , R11 , R 12 , R 17 and R 20 are independently selected from the group consisting of H, C1-C5 alkyl; R 13 , R 14 , R 18 and R 19 are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-C5alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 10.

[0081] In particular, the monomer M4 has the formula (I), (II) or (III)

[0082] [Chem 1]

[0083] O

[0084] O

[0085]

[0086] [Chem 2]

[0087]

[0088] (H)

[0089] [Chem 3]

[0090]

[0091] in which the R substituents 15 , R 16 , R 21 and R 22 are H; R 9 , R 10 , R 11 , R 12 , R 17 and R 20 are independently selected from the group consisting of H, Ci-C5alkyl; R 13 , R 14 , R 18 and R 19 are, independently of each other and independently for each unit n, selected from the group consisting of H and C1-C5 alkyl; n is an integer from 0 to 10.

[0092] More specifically, the M4 monomer has the formula (I), (II) or (III)

[0093] [Chem 1]

[0094] O

[0095] O

[0096] (I)

[0097] (H)

[0098] [Chem 3]

[0099]

[0100] in which the R substituents 15 , R 16 , R 21 and R 22 are H; R 9 , R10 , R 11 , R 12 , R 17 and R 20 are independently selected from the group consisting of H, C1-C5 alkyl; R 13 , R 14 , R 18 and R 19 are H; n is an integer from 0 to 10.

[0101] Pattern M5

[0102] Anhydride-type functional groups may be present in said Al and A2 polymers via the M5 motif of formula X1-C(O)-OC(O)-X2, in which XI and X2 independently represent a polymer chain of said fluorinated polymer Al or acrylic polymer A2. The M5 motif preferably results from the reaction between two acidic functional groups on said fluorinated polymer Al or acrylic polymer A2. Thus, an acidic functional group on a polymer chain of the fluorinated polymer Al may react with another acidic functional group on the same polymer chain, on another polymer chain of the fluorinated polymer Al, or on a polymer chain of acrylic polymer A2.

[0103] Similarly, an acid functional group of a polymer chain of the acrylic polymer A2 can react with another acid functional group carried by the same polymer chain or by another polymer chain of the acrylic polymer A2 or by a polymer chain of the fluorinated polymer Al.

[0104] The M5 pattern can be formed by implementing a dehydration reaction according to techniques known to those skilled in the art.

[0105] Fluorinated polymer Al

[0106] The said fluorinated polymer Al comprises monomeric units derived from a monomer Ml, the latter being vinylidene fluoride (CF2=CH2 or VDF).

[0107] According to one embodiment, the fluorinated polymer Al comprises monomeric units derived from monomer M1 and monomeric units derived from monomer M3 as defined in this application, or monomeric units derived from monomer M4 as defined in this application, or motif M5 as described in this application. Advantageously, the fluorinated polymer Al consists of monomeric units derived from monomer M1 and monomeric units derived from monomer M3, or monomeric units derived from monomer M4 as defined in this application, or motif M5 as described in this application. Said fluorinated polymer Al may comprise at least 90 mole percent of monomeric units derived from monomer M1, advantageously at least 92 mole percent, preferably at least 94 mole percent, more preferably at least 96 mole percent, and in particular at least 98 mole percent.The fluorinated polymer Al may comprise less than 10% by mole of monomeric units derived from monomer M3, M4, or M5, advantageously less than 8% by mole, preferably less than 6% by mole, more preferably less than 4% by mole, and in particular less than 2% by mole. Preferably, the sum of the molar contents of monomeric units derived from monomer M1, M3, M4, or M5 is 100%. The fluorinated polymer Al may be a mixture of two or more polymers as described above. Each fluorinated polymer Al may have different properties, such as, for example, different molecular weights. According to an alternative embodiment, the fluorinated polymer Al is a polymer comprising, in addition to monomeric units derived from monomer M3 or M4 or the motif M5, monomeric units derived from monomer M1 and monomeric units derived from a monomer M1 copolymerizable with vinylidene fluoride.

[0108] Monomers compatible with vinylidene fluoride can be halogenated (fluorinated, chlorinated or brominated) or non-halogenated. Examples of suitable fluorinated monomers, from which monomeric units derived from monomer Ml' are derived, are: vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes and in particular 3,3,3-trifluoropropene, tetrafluoropropenes and in particular 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes and in particular 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene, perfluoroalkyl vinyl ethers and in particular those of general formula Rf-O-CF-CF2, Rf being an alkyl group, preferably in C1 to C2 (preferred examples being perfluoropropyl vinyl ether and perfluoromethyl vinyl ether).

[0109] The fluorinated monomer may contain a chlorine or bromine atom. In particular, it may be selected from bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, and chlorotrifluoropropene. Chlorofluoroethylene may refer to either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

[0110] Thus, said fluorinated polymer Al may comprise monomeric units derived from monomer M1, monomeric units derived from monomer M3 or M4 as defined in this application or motif M5 as described in this application, and monomeric units derived from monomer M1' selected from the group consisting of vinyl fluoride; trifluoroethylene (TrFE); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkylvinyl) ethers such as perfluoro(methylvinyl) ether (PMVE), perfluoro(ethylvinyl) ether (PEVE) and perfluoro(propylvinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of the formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN OR CH2OPO3H; the product of the formula CF2=CFOCF2CF2SO2F; the product of the formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of the formula R 1CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R 2 OCF=CH2 in which R 2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or a mixture thereof.

[0111] Preferably, said fluorinated polymer Al comprises monomeric units derived from monomer M1, monomeric units derived from monomer M3 or M4 as defined in this application or motif M5 as described in this application, and monomeric units derived from monomer M1' selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene and hexafluoropropylene or a mixture thereof. In this alternative embodiment, the fluorinated polymer Al preferably contains at least 50 mole percent of vinylidene fluoride, advantageously at least 60 mole percent of vinylidene fluoride, preferably at least 70 mole percent of vinylidene fluoride, in particular at least 80 mole percent of vinylidene fluoride. The monomeric units derived from the monomer Ml' can be present in a mass content of 1% to 50%, advantageously 2% to 30% by weight relative to the weight of said fluorinated polymer Al.The monomeric units derived from monomer M3 may be present in a molar content of 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5%, based on said fluorinated polymer Al. The monomeric units derived from monomer M4 may be present in a molar content of 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5%, based on said fluorinated polymer Al. The motif M5 may be present in a molar content of 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5%, based on said fluorinated polymer Al.

[0112] In particular, the fluorinated polymer Al is a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (P(VDF-HFP)), having a weight percentage of hexafluoropropylene monomer units of 2 to 30%, advantageously 2 to 25%, preferably 2 to 20%, in particular 4 to 15% by weight relative to the weight of said fluorinated polymer Al, and also comprising 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by mole of monomeric units derived from monomer M3 or 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by mole of monomeric units derived from monomer M4 or 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by moles of M5 motif on the basis of said Al fluorinated polymer. The sum of the constituents being 100%.

[0113] According to another embodiment, the fluorinated polymer Al is a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (P(VDF-HFP)), having a weight percentage of hexafluoropropylene monomer units of 10 to 40%, advantageously 10 to 35% by weight relative to the weight of said fluorinated polymer Al, and also comprising 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by mole of monomeric units from monomer M3 or 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by mole of monomeric units from monomer M4 or 0.05% to 20%, advantageously 0.1 to 10%, preferably 0.5% to 5% by moles of M5 motif on the basis of said Al fluorinated polymer. The sum of the constituents being 100%.

[0114] In one embodiment, the fluorinated polymer Al is a mixture of two or more VDF-HFP copolymers as described above. The presence of hexafluoropropylene comonomers improves the chemical stability of the coating with respect to the active material and the current collector.

[0115] According to one embodiment, the fluorinated polymer Al is a copolymer of vinylidene fluoride and tetrafluoroethylene (TFE), and also comprising from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M3, or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M4, or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of motif M5 based on said fluorinated polymer Al. Preferably, the fluorinated polymer Al comprises at least 40% by mole of vinylidene fluoride, advantageously at least 60% by mole of vinylidene fluoride. at least 70 mol% of vinylidene fluoride, in particular at least 80 mol% of vinylidene fluoride. Preferably, the molar content of tetrafluoroethylene may be between 1 and 50 mol%, in particular between 7 and 45 mol%, more particularly between 10 and 40 mol%.The sum of the constituents being 100%.

[0116] According to one embodiment, the fluorinated polymer Al is a copolymer of vinylidene fluoride and trifluoroethylene (TrFE), and also comprising from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M3 or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M4 or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of motif M5 based on said fluorinated polymer Al. Preferably, the fluorinated polymer Al comprises at least 40% by mole of vinylidene fluoride, advantageously at least 60% by mole of vinylidene fluoride, of preferably at least 70% by moles of vinylidene fluoride, in particular at least 80% by moles of vinylidene fluoride.Preferably, the molar content of trifluoroethylene may be between 15 and 50%, advantageously between 17 and 45 mol%, preferably between 20 and 40 mol%, particularly between 20 and 35 mol%, more particularly between 20 and 30 mol%. The sum of the constituents being 100%.

[0117] According to one embodiment, the fluorinated polymer Al is a copolymer of vinylidene fluoride and chlorotrifluoroethylene (CTFE), and also comprising from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M3 or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of monomeric units derived from monomer M4 or from 0.05% to 20%, advantageously from 0.1% to 10%, preferably from 0.5% to 5% by mole of motif M5 based on said fluorinated polymer Al. Preferably, the fluorinated polymer Al comprises at least 50% by mole of vinylidene fluoride, advantageously at least 60% by mole of vinylidene fluoride. preferably at least 70% by moles of vinylidene fluoride, in particular at least 80% by moles of vinylidene fluoride.Preferably, the molar content of chlorotrifluoroethylene may be between 1 and 20%, advantageously between 2 and 17 mol%, preferably between 3 and 15 mol%, in particular between 4 and 15 mol%, more particularly between 5 and 12 mol%. The sum of the constituents being 100%.

[0118] In one embodiment, the fluorinated polymer Al is a VDF-TFE-HFP terpolymer. The fluorinated polymer Al is a VDF-TrFE-TFE terpolymer (TrFE being trifluoroethylene), and also comprises from 1% to 20%, advantageously from 0.1% to 5%, by moles, of monomeric units derived from monomer M3, or from 1% to 20%, advantageously from 1% to 10%, by moles, of monomeric units derived from monomer M4, or from 1% to 20%, advantageously from 1% to 10%, by moles, of the M5 motif relative to said fluorinated polymer Al. In these terpolymers, the mass content of VDF is at least 10%, the TFE and TrFE comonomers being present in varying proportions. The sum of the constituents is 100%.

[0119] The fluorinated polymer Al preferably has a high molecular weight. By high molecular weight, as used here, is meant a fluorinated polymer Al having a melt viscosity greater than 100 Pa.s, preferably greater than 500 Pa.s, more preferably greater than 1000 Pa.s, according to the ASTM D-3835 method measured at 232°C and 100 sec. 1 .

[0120] In some embodiments, the fluorinated polymer Al is composed of bio-based VDF. The term "bio-based" means "derived from biomass." This improves the separator's environmental footprint. Bio-based VDF can be characterized by a renewable carbon content—that is, carbon of natural origin from a biomaterial or biomass—of at least 1 atomic percent, as determined by the 14C content according to standard NF EN 16640. The term "renewable carbon" indicates that the carbon is of natural origin and comes from a biomaterial (or biomass), as described below.According to some embodiments, the bio-carbon content of VDF may be greater than 5%, preferably greater than 10%, preferably greater than 25%, preferably greater than or equal to 33%, preferably greater than 50%, preferably greater than or equal to 66%, preferably greater than 75%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, preferably greater than 99%, advantageously equal to 100%.

[0121] The fluorinated polymer Al used in the invention can be obtained by known polymerization methods such as emulsion or suspension polymerization by mixing the different monomers M1, M1', M3, M4. The M5 motif can be obtained during the implementation of a dehydration step of the fluorinated polymer Al.

[0122] According to one embodiment, said fluorinated polymer Al is prepared by an emulsion polymerization process in the absence of a fluorinated surfactant.

[0123] The fluorinated polymer Al is generally in the form of a latex having a solids content of 10 to 60% by weight, preferably 10 to 50%, and having a weight-average particle size of less than 1 micrometer, preferably less than 1000 nm, preferably less than 800 nm, and more preferably less than 600 nm. The weight-average particle size is generally at least 20 nm, preferably at least 50 nm, and advantageously the average size is in the range of 100 to 400 nm. The polymer particles may form agglomerates with a weight-average size of 1 to 30 micrometers, and preferably 2 to 20 micrometers. The agglomerates may break down into discrete particles during formulation and application to a substrate.

[0124] According to one embodiment, the Al polymer is semi-crystalline. The semi-crystalline nature of the Al polymer is evaluated by DSC.

[0125] A2 Acrylic Polymer

[0126] Said acrylic polymer A2 comprising monomeric units derived from a monomer M2 of formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 , R 2 and R 3 are independently selected from the group consisting of H and C1-C5 alkyl; R is selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH group(s).

[0127] Preferably, the monomer M2 has the formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 , R 2 and R 3are independently selected from the group consisting of H and C1-C5 alkyl; R is selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, n-dodecyl, amyl, isoamyl, hexyl, 2-ethylhexyl, lauryl, n-octyl, hydroxybutyl, hydroxypropyl and hydroxyethyl.

[0128] In particular, said monomer M2 has the formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 and R 2 are H; R 3 is H or CH3; R is selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, hydroxypropyl, and hydroxybutyl. More specifically, said monomer M2 has the formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 and R 2 are H; R 3is H or CH3; R is selected from the group consisting of methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, hydroxypropyl and hydroxybutyl.

[0129] Thus, the monomer M2 can be methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, methacrylate 2-Ethylhexyl, lauryl methacrylate, n-octyl methacrylate and mixtures thereof.Among these, alkyl acrylates with an alkyl group having 1 to 8 carbon atoms are preferred, and alkyl acrylates with an alkyl group having 1 to 5 carbon atoms are even more preferred. These compounds can be used alone or in mixtures of two or more.

[0130] The acrylic polymer A2 may also comprise monomeric units derived from a monomer M2' copolymerizable with monomer M2. The monomer M2' may be:

[0131] - (A) an alkenyl compound containing a functional group, and / or

[0132] - (B) an alkenyl compound without a functional group.

[0133] The alkenyl compound (A) containing a functional group includes, for example, α,P-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid and the like; vinyl ester compounds such as vinyl acetate, vinyl neodecanoate and the like; amide compounds such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, diacetone acrylamide and the like; acrylic acid esters such as 2-hydroxyethyl acrylate, N-dialkylaminoethyl acrylate, glycidyl acrylate, n-dodecyl acrylate, fluoroalkyl acrylate and the like;Methacrylic acid esters such as dialkylaminoethyl methacrylate, fluoroalkyl methacrylate, 2-hydroxyethyl methacrylate, n-octyl methacrylate, t-butyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, and the like; maleic anhydride; and alkenyl glycidyl ether compounds such as allyl glycidyl ether and the like. Of these, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, N-methylolacrylamide, N-methylolmethacrylamide, diacetone acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and allyl glycidyl ether are preferred. These compounds can be used alone or in a mixture of two or more.

[0134] Alkenyl compounds without a functional group (B) include, for example, conjugated dienes such as 1,3-butadiene, isoprene, and the like; divinyl hydrocarbon compounds such as divinyl benzene and the like; and alkenyl cyanides such as acrylonitrile, methacrylonitrile, and the like. Among these, 1,3-butadiene and acrylonitrile are preferred. These compounds can be used alone or in mixtures of two or more.

[0135] Preferably, the functional alkenyl compound (A) should be used in a proportion of less than 50% by weight relative to the weight of the monomer mixture, and the alkenyl compound without a functional group (B) should be used in a proportion of less than 30% by weight relative to the weight of the monomer mixture. The acrylic polymer A2 used in the invention can be obtained by known polymerization methods such as emulsion or suspension polymerization by mixing the different monomers M2, M2', M3, and / or M4. The motif M5 can be obtained by carrying out a dehydration step of the fluorinated polymer A2.

[0136] According to a preferred embodiment, said acrylic polymer A2 comprises from 10 to 99 mole percent of monomer M2, from 1 to 90 mole percent of monomeric units M3 or monomeric units M4 or motifs M5, and from 0 to 50 mole percent of monomeric units M2'.

[0137] The said A2 acrylic polymer can also be cross-linked to limit its swelling in Li-ion battery electrolytes.

[0138] Preparation of said binder

[0139] The binder according to the present invention comprises a mixture of polymer Al and polymer A2 as described in this application. The binder can be prepared by dissolving both polymers Al and A2 in an organic solvent. The binder can be prepared by mixing the two polymers in powder form using methods known to those skilled in the art. The binder can be prepared by mixing the two polymers in an aqueous solution and then drying the solution.

[0140] Preferably, in said binder, the mass ratio A1 / A2 varies from 95 / 5 to 5 / 95, preferably from 95 / 5 to 25 / 75, in particular from 95 / 5 to 50 / 50.

[0141] electrode composition

[0142] The electrode composition according to the present invention comprises at least one active material, at least one conductive agent and said binder according to the present invention.

[0143] The active material is chosen from the group consisting of LiCoO2, Li(Ni, Co, Al)O2, Li(i + X )Neither a Mn b Co c O2 (x represents a real number of 0 or more, a = 0.9, 0.8, 0.6, 0.5, or 1 / 3, b = 0.05, 0.1, 0.2, 0.3, or 1 / 3, c = 0.05, 0.1, 0.2, or 1 / 3), Li NiO2, LiMn2O4, LiCoMnC, LiaNiMnaOa, Li3Fe2(PO4)3, Li 3 2 (PO )3, a Li Mn spinel substituted by a different element having a composition represented by Lii +x Mn2- x.y M y O4, M representing at least one metal chosen from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate Li x TiO y- x and y independently represent a real number between 0 and 2, and a lithium metal phosphate has a composition represented by LiMPO4, where M represents Fe, Mn, Co, or Ni. Furthermore, the surface of each of the materials described above can be coated. The coating material is not particularly limited as long as it has lithium ion conductivity and contains a material capable of being maintained as a coating layer on the surface of the active material. Examples of coating materials include LiNbO3, Li4Ti5O12, and Li3PO4. The shape of the active cathode material is not particularly limited but is preferably particulate.

[0144] Preferably, said active material is selected from the group consisting of LiFePO4 and LiNi x Co y Mn z O min which x is greater than or equal to 0.6, y is less than or equal to 0.2, z is less than or equal to 0.2, and x+y+z =1 and m is the number of oxygen atoms in the compound to have an electronically balanced molecule.

[0145] In particular, the active material is selected from the group consisting of LiFePO4 and LiNi x Co y Mn z O m in which x is greater than or equal to 0.8, y is less than or equal to 0.1, z is less than or equal to 0.1, and x+y+z =1 and m is the number of oxygen atoms in the compound to have an electronically balanced molecule.

[0146] The conductive agents in the electrode are composed of one or more materials that can improve conductivity. Some examples include carbon blacks such as acetylene black, Ketjen black; carbon fibers, such as a carbon nanotube, a carbon nanofiber, a vapor-phase growth carbon fiber; metal powders such as SUS powder, and aluminum powder.

[0147] The electrode composition may also include a solvent such as water or an organic solvent. The organic solvent is preferably selected from the group consisting of n-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), triethylphosphite (TEP), acetone, cyclopentanone, tetrahydrofuran, methyl ethylketone (MEK), methyl isobutyl ketone (MiBK), ethyl acetate (EA), butyl acetate (BA), ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), gamma-butyrolactone and N-butylpyrrolidone; and mixtures thereof.

[0148] Use

[0149] The electrode composition can be used in the preparation of an electrode, preferably a positive electrode. The positive electrode comprises a metallic collector, at least one face of which is coated with the electrode composition according to the present invention. The electrode composition is deposited on at least one surface of the metallic collector, and then the electrode is dried to remove any solvent or water that may be present. After evaporation of the water or solvent, the electrode composition preferably has the following mass composition:

[0150] a. 80% to 99.9% active material, preferably 80% to 99%,

[0151] b. 0.05% to 10% of conducting agent, preferably 10% to 0.5%,

[0152] c. 0.05% to 10% of the binder according to the present invention, preferably 10% to 0.5%; the sum of the percentages being 100%.

[0153] The electrode's metal collector is typically made of aluminum for the cathode. The metal collector may have a surface treatment and a conductive primary layer 5 µm or thicker. Alternatively, the metal collector may be made of woven or non-woven carbon fiber. The electrode is consolidated by heat treatment through an oven, under an infrared lamp, in a calender with heated rollers, or in a platen press. Another alternative is a two-step process. First, the electrode undergoes heat treatment in an oven, under an infrared lamp, or in contact with heated plates without pressure. Then, a compression step at room temperature or under heat is performed using a calender or platen press. This step adjusts the electrode's porosity and improves adhesion to the metal collector.

[0154] According to another aspect, the present invention provides a lithium ion battery comprising a negative electrode, a positive electrode according to the present invention and a separator between said positive electrode and said negative electrode.

[0155] According to another aspect, the present invention provides an electrochemical device comprising a negative electrode, a positive electrode according to the present invention and an electrolyte comprising lithium.

[0156] Examples

[0157] Binders 1 to 4 are prepared as described in Table 1 below. Polymers Al and A2 are obtained by an emulsion polymerization process. The MMA / anhydride copolymer comprises 10 mol% of maleic anhydride units and the remainder MMA. The MMA / AA copolymer comprises 10 mol% of acrylic acid units and the remainder MMA. The VDF / AA copolymer comprises 1% of acrylic acid units and the remainder vinylidene fluoride.

[0158] [Table 1]

[0159] Al Polymer A2 Polymer A1 / A2 Ratio

[0160] Binder 1 (comp.) Homopolymer VDF Copolymer MMA / Anhydride 90 / 10

[0161] Binder 2 (comp.) Homopolymer VDF Copolymer MMA / AA 90 / 10

[0162] Binder 3 (comp.) VDF / AA copolymer MMA / AA 90 / 10 copolymer

[0163] Binder 4 (invention) VDF / AA copolymer MMA / Anhydride 90 / 10 copolymer

[0164]

[0165] VDF: vinylidene fluoride; AA: acrylic acid; MMA: methyl methacrylate; Anhydride: maleic anhydride. The fabrication of an electrode formulation was carried out by following these steps: a 9% (w / w) solution of the polymer mixture was prepared in N-methyl-2-pyrrolidone until both polymers were completely dissolved. Then, Super P C65 carbon black was added to this solution. The solution was mixed using a mechanical stirrer. Next, the active material NMC811 was added. More N-methyl-2-pyrrolidone could then be added to adjust the final dry extract. The resulting ink contained, by weight, 97 parts carbon-coated active materials, 1.5 parts carbon black, and 1.5 parts polymers per 100 parts of the active materials / carbon black / polymer mixture.

[0166] Measuring membership

[0167] The adhesion between the layer formed by the mixture of active materials / carbon black / polymers and the aluminum foil is measured. To do this, a 25 mm wide strip is cut. This strip is then adhered to a rigid aluminum plate using double-sided adhesive, with the adhesive applied to the side of the active materials / carbon black / polymer coating. The peel test is performed using an Instron 34SC1 dynamometer. The rigid aluminum plate is held in one jaw, and the coated aluminum foil in the other. In this configuration, the peel angle is 180°. The jaw movement speed is set at 100 mm / min.

[0168] Measurement of the viscosity of the electrode formulation applicable to a metallic support

[0169] The viscosity of the electrode formulations was measured at 23°C using a TA HR 10 rheometer. The ink, containing by weight 97 parts active materials, 1.5 parts carbon black, and 1.5 parts polymers per 100 parts of the active materials / carbon black / polymers mixture, was deposited between two parallel plates (40 mm diameter) separated by a 1 mm gap. Viscosity values ​​were obtained at various shear rates ranging from 0.1 s⁻¹. 1 at 100 s 1 The value of 10s 1 is taken as a comparison between the different formulations.

[0170] Measurement of the delta of the electrode formulation applicable to a metallic support

[0171] The dynamic viscosity of the electrode formulations was measured at 23°C using a TA HR 10 rheometer. The ink, containing by weight 97 parts active materials, 1.5 parts carbon black, and 1.5 parts polymers per 100 parts of the active materials / carbon black / polymers mixture, was deposited between two parallel plates (40 mm diameter) separated by a 1 mm gap. Dynamic viscosity values ​​were obtained at various stress levels ranging from 0.1% to 100% at an oscillation frequency of 1 Hz. The delta was then calculated using a formula known to those skilled in the art. The delta value at 1% was used for comparison between the different formulations.

[0172] Slurry stability

[0173] The electrode formulation was prepared as follows: a 9% (w / w) solution of the polymer mixture was prepared in N-methyl-2-pyrrolidone until both polymers were completely dissolved. Super P C65 carbon black was then added to this solution and mixed with a mechanical stirrer. Next, the active material NMC811 was added. Additional N-methyl-2-pyrrolidone could then be added to adjust the final dry extract. The resulting ink contained, by weight, 97 parts carbon-coated active material, 1.5 parts carbon black, and 1.5 parts polymer per 100 parts active material / carbon black / polymer mixture. The electrode formulations were then stored for 72 hours, and their dynamic viscosity was measured. Table 2 below shows the delta of different formulations. When the delta is less than 45°, the electrode formulation is not processable.

[0174] Table 2]

[0175] Polymer Mixture Dry Extract (%) Delta (°)

[0176] Binder 1 72.9 20

[0177] Binder 2 72.9 25

[0178] Binder 3 72.7 35

[0179] Binder 4 (invention) 72.7 52

[0180]

[0181] As we can see, the binder according to the present invention exhibits a delta greater than 45°, which the other comparable binders cannot achieve. The binder according to the present invention improves the processability of the electrode.

[0182] Only binder 4 according to the present invention exhibits a delta greater than 45° after 72 hours of aging. It therefore presents the best stability in solution.

[0183] Membership

[0184] The previous electrode formulations were then deposited onto an aluminum foil to achieve a wet thickness between 180 µm and 200 µm. The NMP was then evaporated by heating the coated foil for 2 minutes at 50°C and then for 30 minutes at 150°C. This resulted in a coating with a loading of between 22 and 23 mg / cm². 2 The electrodes were then calendered to a density of 3.5 g / cm³ 3 The adhesion of the different electrodes was then measured. Table 3 below shows the results obtained.

[0185] [Table 3]

[0186] Polymer Mixture Loading (mg / cm³) 2 Adhesion (N / m)

[0187] Binder 1 22.7 105

[0188] Binder 2 23.0 12

[0189] Binder 3 22.9 70

[0190] Binder 4 (invention) 22.1 175

[0191]

[0192] The binder 4 based on the mixture according to the present invention exhibits the best adhesion value.

Claims

Demands 1. Electrode binder comprising a fluorinated polymer Al including monomeric units derived from a monomer M1 being vinylidene fluoride and an acrylic polymer A2 including monomeric units derived from a monomer M2 of formula R 1 R 2 C=C(R 3 )C(O)OR in which the R substituents 1 , R 2 and R 3 are independently selected from the group consisting of H and C1-C5 alkyl; R is selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH group(s); characterized in that: said fluorinated polymer Al also comprises monomeric units derived from a monomer M3 bearing an acid functional group, and said acrylic polymer A2 also comprises at least one anhydride functional group; or said fluorinated polymer Al also comprises at least one anhydride functional group and said acrylic polymer A2 also comprises monomeric units derived from a monomer M3 bearing an acid functional group.

2. Binder according to the preceding claim, characterized in that the monomer M3 has the formula R 4 R 5 C=C(R 6 )((X 3 ) P -HORN 7 ) in which the R substituents 4 , R 5 and R 6 are independently selected from the group consisting of H and Ci-C5alkyl; R 7 is selected from the group consisting of -OR 8 with R 8 selected from the group consisting of H and Ci-Ci8alkyl substituted by one or more group(s) selected from the group consisting of -CO2H, SO3H, -C(O)OR 8 ', -OC(O)R 8 ' ; R 8' is selected from the group consisting of Ci-C5alkyl and C6-Ci2aryl substituted by one or more CO2H, SO3H functional groups; X 3 is selected from the group consisting of -[-C(O)OC(R 23 (R 24 )C(R 25 (R 26 )-] w i- and an alkyl hydrocarbon group Ci-Cio optionally bearing one or more -CO2H, SO3H group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 23 , R 24 , R 25 , R 26 are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5alkyl; p is 0 or 1.

3. Binder according to any one of the preceding claims, characterized in that said anhydride function is introduced into the Al or A2 polymer either by monomeric units derived from a monomer M4 is of formula (I), (II) or (III)[Chem 1] O O (I) [Chem 2] (H) [Chem 3] in which the R substituents 9 , R 10 , R 11 , R 12 , R 15 , R 16 , R 17 , R 20 , R 21 and R 22 are independently selected from the group consisting of H, C1-C5 alkyl; R 13 , R 14 , R 18 and R 19are, independently of each other and independently for each unit n, selected from the group consisting of H and Ci-Ci8alkyl optionally substituted by one or more -OH, CO2H, CO2R' group(s) with R' being Ci-Cio alkyl optionally substituted by one or more -OH or CO2H group(s); n is an integer from 0 to 12; or a mixture of these; said polymer Al or A2 comprises the motif M5 of formula X1-C(O)-OC(O)-X2 in which XI and X2 independently represent a polymer chain of said fluorinated polymer Al or of the acrylic polymer A2. Binder according to any one of the preceding claims characterized in that the fluorinated polymer Al comprises monomeric units derived from a monomer Ml' selected from the group consisting of vinyl fluoride, trifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes, tetrafluoropropenes, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes, perfluoroalkylvinyl ethers, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene and ethylene or a mixture thereof.5.Binder according to any one of the preceding claims characterized in that said acrylic polymer A2 comprises monomeric units derived from a monomer M2 selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-dodecyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, n-octyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethyl (meth)acrylate, and mixtures thereof.

6. Binder according to any one of the preceding claims characterized in that the mass ratio A1 / A2 varies from 95 / 5 to 5 / 95.

7. Electrode composition comprising at least one active material, at least one conductive agent and said binder according to any one of claims 1 to 6.

8. Electrode composition according to the preceding claim, characterized in that said active material is selected from the group consisting of LiCoO2, Li(Ni, Co, Al)O2, Li(i +X )Neither a MnbCo c O2 with x representing a real number of 0 or more, a = 0.8, 0.6, 0.5, or 1 / 3, b = 0.1, 0.2, 0.3, or 1 / 3, c = 0.1, 0.2, or 1 / 3, Li NiO2, LiMn2O4, LiCoMnO4, Li3NiMn3O3, Li3Fe2(PO4)3, Li 3 2 (PO4)3, a LiMn spinel substituted by a different element having a composition represented by Lii +x Mn 2.x .yM y O4, M representing at least one metal chosen from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate Li x TiO ywith x and y independently representing a real number between 0 and 2, and a metal and lithium phosphate having a composition represented by LiMPO4, M representing Fe, Mn, Co, or Ni.

9. Electrode composition according to claim 7 or 8 characterized in that said conducting agent is selected from the group consisting of carbon blacks, such as acetylene black, Ketjen black; carbon fibers, such as a carbon nanotube, a carbon nanofiber, a carbon fiber by vapor phase growth; metal powders such as a SUS powder, and an aluminum powder; and mixtures thereof.

10. Positive electrode comprising a metallic collector of which at least one face is coated with said electrode composition according to any one of claims 7 to 9.

11. Lithium ion battery comprising a negative electrode, a positive electrode according to the preceding claim and a separator between said positive electrode and said negative electrode.

12. Electrochemical device comprising a negative electrode, a positive electrode according to the preceding claim and an electrolyte comprising lithium.

Images