Polyamic acid derivative adhesives for lithium-ion batteries

Abstract

This invention relates to lithium-ion polyamic acid derivatives and their use as binders in electrodes for lithium-ion batteries.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 003253, filed March 3, 2020, and European Application No. 20172958.9, filed May 5, 2020, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0003] This invention relates to lithium-ion polyamic acid derivatives and their use as binders in electrodes for lithium-ion batteries. Background Technology

[0004] Lithium-ion batteries (LIBs) have been used in various portable electronic devices and are sought as a power source for hybrid electric vehicles and electric vehicles. To meet the needs of large-scale applications, improved energy density and power capacity of LIBs are desired.

[0005] Currently, the trend in lithium-ion batteries is to increase their energy capacity by increasing lithium storage in the anode. For this purpose, conventional silicon-rich graphite anodes have attracted considerable interest due to their much higher theoretical energy capacity.

[0006] Silicon (Si) has high capacity (at room temperature compared to Li) 3.75 Si is 3572mAh g -1 Weight, capacity and 8322mAh cm -3 Silicon exhibits high volumetric capacity and low charge-discharge potential (approximately 0.4V delithiation voltage). Unfortunately, silicon also experiences extremely large volume changes (>400%) during lithium-ion alloying (anisotropic volume expansion).

[0007] This volume change leads to several drawbacks. For example, it can cause severe fragmentation and disrupt the electrical contact between the silicon particles and the carbon conductive agent. It can also lead to the formation of an unstable solid electrolyte interphase (SEI), resulting in electrode degradation and rapid capacity decay (especially at high current densities).

[0008] For the reasons mentioned above, electrode preparations for silicon anodes contain at most 20% silicon compound by weight, with the remainder being graphite. Specifically, electrode preparations containing graphite and silicon compound in amounts ranging from 5% to a maximum of 20% by weight were investigated.

[0009] Traditionally, all graphite negative electrodes rely on polyvinylidene fluoride (PVDF) as a binder. PVDF interacts favorably with graphite particles but does not adhere well to silicon particles, making the binder prone to failure (due to the mechanical stress caused by the expansion and contraction of silicon during charging cycles).

[0010] Recently, there has been a growing pursuit of methods that typically avoid the use of organic solvents in order to ensure more environmentally friendly technologies.

[0011] As an example, water-based slurries used as adhesives comprising carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) are known in the art. However, CMC / SBR-based adhesives are brittle and have been found to generate failure points within the adhesive matrix itself. Furthermore, water-based slurries used as adhesives comprising CMC / SBR exhibit high resistivity and thus reduced lifetime characteristics (EP2874212).

[0012] Currently, lithium polyacrylate (LiPAA) exhibits the best properties among silicon-active materials, but it is prone to breakage and has low toughness. Therefore, when LiPAA is bent into a cylindrical shape, it will break or crack, making it suitable only for coin cells.

[0013] Polyimides have desirable properties when used as binders in negative electrodes. They possess desirable mechanical properties, chemical resistance, and heat resistance, but they are insoluble in water and have low initial charge / discharge efficiency.

[0014] Water-soluble polyamic acid can be used as a binder to provide polyimide via a post-treatment imidization process. However, when using this method to manufacture electrodes, it is difficult to raise the electrode plate temperature to the 160°C or higher required for imidization due to the oxidation of the copper (Cu) substrate, resulting in a low curing rate for the polyimide binder. With a low curing rate, the carboxylic acid groups of the polyamic acid directly bind to lithium ions, leading to an irreversible reaction and reduced initial efficiency. Furthermore, the presence of unstable amide bonds can negatively impact battery life.

[0015] Therefore, despite the high bonding strength and good mechanical and physical properties of polyimide adhesives, they are not suitable for practical industrial use due to unstable bonding caused by difficulties in low-temperature curing, reduced initial efficiency caused by irreversible lithium-ion reactions, and long-term reliability degradation caused by insolubility in water.

[0016] One object of the present invention is to provide a polymeric adhesive that can be effectively used as an adhesive for silicon anodes. Summary of the Invention

[0017] An adhesive composition for lithium batteries is provided, comprising a water-soluble polyamic acid derivative.

[0018] In a first aspect, the present invention relates to water-soluble aromatic polyamic acid derivatives [polymers (PA)], the polyamic acid derivatives comprising:

[0019] a) at least 50 mol% of repeating unit (L), said repeating unit (L) comprising at least one acid moiety in the form of an ester;

[0020] b) 0 to 50 mol% of repeating unit (M), said repeating unit (M) comprising at least one acid moiety in the form of itself or an imide thereof;

[0021] c) 25 to 50 mol% of repeating unit (N), said repeating unit (N) comprising at least one acidic portion as a salt.

[0022] According to a second aspect of the invention, the polymer (PA) described above can be incorporated into an aqueous adhesive composition (B), which comprises the polymer (PA) as defined above and at least one aqueous solvent.

[0023] In another aspect, the present invention relates to a composition for forming an electrode [composition (C)], the composition comprising:

[0024] (A) An adhesive composition as defined above; (B)

[0025] (B) At least one electroactive material;

[0026] (C) Optionally, a thermal initiator; and

[0027] (D) Optionally, an additive that imparts conductivity.

[0028] In another aspect, the present invention relates to the use of the electrode-forming composition (C) for manufacturing an electrode [electrode (E)], the method comprising:

[0029] (i) Provide a metal substrate having at least one surface;

[0030] (ii) Provide an electrode-forming composition as defined above [Composition (C)];

[0031] (iii) Applying the composition (C) provided in step (ii) to at least one surface of the metal substrate provided in step (i) to provide an assembly comprising a metal substrate having the composition (C) coated on at least one surface of the metal substrate;

[0032] (iv) Dry the component provided in step (iii);

[0033] (v) subject the dried component obtained in step (iv) to a compression step to obtain the electrode (E) of the present invention.

[0034] In another aspect, the present invention relates to electrodes [electrodes (E)] that can be obtained by the method of the present invention.

[0035] In another objective, the present invention relates to an electrochemical device comprising at least one electrode (E) of the present invention. Detailed Implementation

[0036] In the context of this invention, the term "weight percentage" (wt%) indicates the content of a specific component in a mixture, calculated as the ratio between the weight of that component and the total weight of the mixture. When referring to a repeating unit derived from a monomer in a polymer / copolymer, weight percentage (wt%) indicates the ratio between the weight of that repeating unit of that monomer and the total weight of the polymer / copolymer. When referring to the total solids content (TSC) of a liquid composition, weight percentage (wt%) indicates the ratio between the weights of all non-volatile components in the liquid.

[0037] As used herein, “water-soluble” or “water-soluble” means that at least 99 wt.% of the polymer (PA) is dissolved in deionized water to form a homogeneous solution.

[0038] The term "electrochemical device" is intended to refer to an electrochemical cell unit comprising a positive electrode, a negative electrode, and a liquid electrolyte, wherein a single or multiple membrane is adhered to at least one surface of one of the electrodes.

[0039] Non-limiting examples of electrochemical devices include batteries, preferably secondary batteries and double-layer capacitors.

[0040] For the purposes of this invention, "secondary battery" is intended to refer to a rechargeable battery. Notably, non-limiting examples of secondary batteries include alkali metal or alkaline earth metal secondary batteries.

[0041] The term "aqueous" here is intended to refer to a medium that includes pure water and water combined with other components, which do not substantially alter the physical and chemical properties exhibited by water.

[0042] The term "aromatic polyamic acid derivative" is intended to mean any polymer comprising at least 50 mol% of repeating units comprising an amide moiety and at least one acid moiety, wherein the acid moiety is in the form of an ester; and at least 25 mol% of repeating units comprising an amide moiety and at least one acid moiety, wherein the acid moiety is in the form of a salt.

[0043] The repeating unit (L) is preferably selected from a group of units having any one of the terms (L1) to (L4):

[0044]

[0045] in

[0046] -Ar is a trivalent aromatic moiety that is selected from the group consisting of substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms.

[0047] -Ar' is a tetravalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms.

[0048] - Each R1 is independently H or an alkyl group, preferably H or an alkyl group having 1 to 5 carbon atoms;

[0049] -R is a divalent aromatic group; preferably, R is selected from the group consisting of the following structures:

[0050]

[0051] And the corresponding optionally substituted structures, wherein Y is selected from the group consisting of: -O-, -S-, -SO2-, -CH2-, -C(O)-, -C(CF3)2-, -(CF2). p -,p is an integer from 0 to 5.

[0052] More preferably, R is:

[0053]

[0054] - Each Z is independently selected from the following groups:

[0055] ·O-(CH2) k -O-CO-CH=CHR4, where k is from 1 to 20, preferably from 1 to 8, more preferably from 2 to 6, and even more preferably equal to 2 or 3; and R4 is H or an alkyl group, preferably an alkyl group having 1 to 5 carbon atoms;

[0056] ·O-(CH2) p -Ar-CR5 = CHR6 or O-(CH2) p -OAr-CR5=CHR6, where p is 0 to 20, preferably from 1 to 8; Ar contains one or two aromatic rings or heteroaromatic rings; R5 and R6 are H, alkyl, preferably alkyl having 1 to 5 carbon atoms, phenyl or COOR7, where R7 is H or alkyl, preferably alkyl having 1 to 5 carbon atoms;

[0057] ·O-(CH2) q -CH=CHR8 where q is from 0 to 20, preferably from 1 to 8; and R8 is H or an alkyl group, preferably an alkyl group having 1 to 5 carbon atoms;

[0058] ·O-(CH2)r -O-CH=CHR9 where r is from 0 to 20, preferably from 1 to 8; and R9 is H or an alkyl group, preferably an alkyl group having 1 to 5 carbon atoms.

[0059] The repeating unit (M) is preferably selected from a group of units having any one of the terms of the general formula (M1) to (M4):

[0060]

[0061] Ar, Ar', R, and R1 are, as defined above, themselves or their imide forms.

[0062] The repeating unit (N) is preferably selected from a group of units having any one of the terms of the general formula (N1) to (N4):

[0063]

[0064] Ar, Ar', R, and R1 are defined as above, and

[0065] -Cat + It is a monovalent cation, preferably selected from alkali metal cations, protonated primary, secondary or tertiary ammonium cations and quaternary ammonium cations, more preferably selected from Na + K+ and Li + Li, or even better + .

[0066] The trivalent aromatic moiety Ar and the tetravalent aromatic moiety Ar' in the repeating units (L), (M) and (N) defined above can independently have adjacent, meta- or anti-connections with other moiety.

[0067] Preferably, the polymer (PA) of the present invention is a water-soluble derivative of polyamic acid, which includes:

[0068] a) A group consisting of repeating units of at least 50 mol% of units selected from either general formula (L2) or (L4);

[0069] b) Repeating units of groups consisting of 0 to 50 mol% of units selected from any one of the general formulas (M2) or (M4);

[0070] c) 25 to 50 mol% of repeating units of a group consisting of units selected from either general formula (N2) or (N4).

[0071] In a preferred embodiment of the invention, Cat in the repeating units (N1) to (N4) + It is Li + .

[0072] Most preferably, the polymer (PA) comprises:

[0073] a) A group consisting of repeating units of at least 50 mol% of any one of the terms in general formula (L2);

[0074] b) Repeating units of a group consisting of 0 to 50 mol% of any term in the general formula (M2);

[0075] c) 25 to 50 mol% of repeating units of a group consisting of any one of the terms in the general formula (N2);

[0076] In a particularly preferred embodiment, Z in the repeating unit (M) is of the formula O-(CH2). k The group is -O-CO-CH=CHR4, wherein k is from 2 to 6, or more preferably equal to 2 or 3; and R4 is H or an alkyl group, preferably H.

[0077] The relative amounts of repeating units (L1) to (L4), (M1) to (M4) and (N1) to (N4) in the polymer (PA) of the present invention can be determined by any suitable method.

[0078] In particular, the amount of repeating units (M) in the form of imide (the degree of imidization of the polymer (PA)) can be assessed by NMR, and the amount of repeating units (L), (N) and (M) in the form of acid can be assessed by NMR, elemental analysis or titration.

[0079] The polymer (PA) can be manufactured by a method comprising a polycondensation reaction between at least one acidic monomer and at least one diamine comonomer containing one or two aromatic rings, followed by partial esterification of the acidic moiety to prepare the polymer (P-A0). The resulting partially esterified polymer (P-A0) is then partially salted to obtain at least a portion of the acidic moiety in salt form.

[0080] According to the first embodiment, the method for preparing the polymer (P-A0) includes at least the following steps:

[0081] i) Provide at least one formula R n R m NR-NR n R m The diamine comonomer, wherein R is as defined above and R n and R m Each is independently H or an alkyl group, preferably H or an alkyl group having 1 to 5 carbon atoms;

[0082] ii) Combine the diamine comonomer provided in step i) with a compound of any one of formulas (I) to (IV):

[0083]

[0084] Where Ar and Ar' are as defined above, and X is OH, Cl, Br, F, or I.

[0085] The reaction occurs in the presence of a polar aprotic solvent and an organic base.

[0086] iii) React the polymer obtained in step ii) with a compound selected from the following:

[0087] ·NR a R b R c -(CH2) k -O-CO-CH=CHR4, where k and R4 are defined as above.

[0088] ·NR a R b R c -(CH2) p -Ar-CR5 = CHR6, where p, Ar, R5, and R6 are defined as above.

[0089] ·NR a R b R c -(CH2) q -CH = CHR8, where q and R8 are defined as above.

[0090] ·NR a R b R c -(CH2) r -O-CH = CHR9, where r and R9 are defined as above.

[0091] Where R a R b and R c It is independently H or alkyl, preferably an alkyl group having 1 to 5 carbon atoms.

[0092] Among the compounds of formula (IV), trimellitic anhydride monoacyl chloride (TMAC) is preferred:

[0093]

[0094] In the compounds of formula (III), pyromellitic dianhydride (PMDA) is preferred:

[0095]

[0096] Preferably, the diamine comonomer is selected from the group consisting of: 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminodiphenyl ether (ODA), m-phenylenediamine (MPDA), and combinations thereof.

[0097]

[0098] According to an embodiment, the polar aprotic solvent is selected from the group consisting of: chlorobenzene, chloroform, N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolinone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and sulfolane.

[0099] According to the examples, the organic base is selected from the group consisting of pyridine and alkylamines, such as trimethylamine.

[0100] The polymer (PA) can be prepared from a polymer (P-A0) copolymer by at least partially neutralizing the acid groups with a salt (preferably an alkali metal salt) including the monovalent cation Cat+ in a suitable solvent.

[0101] The salt can be any alkali metal salt capable of neutralizing acidic groups. In some embodiments, the salt is selected from the group consisting of lithium carbonate, lithium hydroxide, lithium bicarbonate, and combinations thereof, preferably lithium carbonate. In some embodiments, the lithium salt does not contain lithium hydroxide.

[0102] The solvent used in the salt-forming step of the polymer (P-AO) to provide the polymer (PA) can be any solvent capable of dissolving both the salt and the resulting polymer (PA). Preferably, the solvent is selected from at least one of aqueous solvents, such as water, NMP, and alcohols (e.g., methanol, isopropanol, and ethanol). Preferably, the solvent includes less than 5 wt.%, more preferably less than 2 wt.%, and more preferably less than 1 wt.% of NMP. More preferably, the solvent is NMP-free. Most preferably, the solvent is an aqueous solvent. Even more preferably, the solvent is water.

[0103] Preferably, the concentration of salt in the solvent ranges from 0.5 to 30 wt.%, more preferably from 5 to 30 wt.%, and more preferably from 10 to 30 wt.%, based on the total weight of the solvent and salt.

[0104] In some embodiments, wherein the salt is a lithium salt, the concentration of the lithium salt in the solvent provides at least 0.5 eq., 1 eq., 1.5 eq., 2 eq., 2.5 eq., 3 eq., or 4 eq of lithium to the acid group. In some embodiments, the concentration of the lithium salt in the solvent provides at most 5 eq., preferably at most 4 eq. of lithium to the acid group.

[0105] The polymer (PA) is separated from the solution as a solid after salt formation and optionally stored for later use. The solid polymer (PA) can also be dissolved (or redissolved) in water to prepare the composition for forming electrodes as described below. However, preferably, the solution containing the polymer (PA) after salt formation is an aqueous solution that can be used directly to prepare the binder composition as described below, optionally further diluted with water.

[0106] In another aspect, the present invention relates to a composition for forming an electrode [composition (C)], the composition comprising:

[0107] (A) An adhesive composition as defined above; (B)

[0108] (B) At least one electroactive compound;

[0109] (C) Optionally, a thermal initiator; and

[0110] (D) Optionally, an additive that imparts conductivity.

[0111] As is known in the art, compositions for forming electrodes are compositions of matter, typically fluid compositions, in which solid components are dissolved or dispersed in a liquid, which can be applied to a metal substrate and subsequently dried to form an electrode, wherein the metal substrate acts as a current collector. Electrode-forming compositions typically comprise at least one electroactive material and at least one binder.

[0112] The electrode forming composition of the present invention [composition (C)] comprises one or more water-soluble aromatic polyamic acid derivatives [polymer (PA)] as defined above, which are used as adhesives.

[0113] The preparation of the composition for forming the electrode includes the preparation of an aqueous binder composition, followed by the addition of powdered electrode material.

[0114] The aqueous adhesive composition (B) of the present invention can be prepared by dissolving the polymer (PA) in an aqueous solvent, more preferably in water.

[0115] To obtain the adhesive solution (B) detailed above, it is preferable to dissolve 1-15 wt. parts, particularly 5-10 wt. parts, of the copolymer (PA) in 100 wt. parts of an aqueous solvent.

[0116] In a preferred embodiment, the binder composition (B) is an aqueous solution comprising a polymer (PA) obtained after partial salt formation, which can be used directly to prepare a composition for forming electrodes, optionally further diluted with water.

[0117] The electrode-forming composition [composition (C)] of the present invention includes one or more electroactive materials. For the purposes of the present invention, the term "electroactive material" is intended to mean a compound that is capable of incorporating or inserting alkali metal or alkaline earth metal ions into its structure and substantially releasing alkali metal or alkaline earth metal ions during the charging and discharging phases of an electrochemical device. The electroactive material is preferably capable of incorporating or inserting and releasing lithium ions.

[0118] The nature of the electroactive material in the electrode-forming composition (C) of the present invention depends on whether the composition is for manufacturing a negative electrode (anode) or a positive electrode (cathode).

[0119] In the case of forming a positive electrode for a lithium-ion secondary battery, the electroactive material may include a lithium-containing compound. In one embodiment, the lithium-containing compound may be a metal chalcogenide of the formula LiMQ2, where M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr, and V, and Q is a chalcogen element such as O or S. Among these, a lithium-based metal oxide having the formula LiMO₂ is preferably used, where M is as defined above. Preferred examples thereof may include LiCoO₂, LiNiO₂, LiNi x Co 1-x O₂ (0 < x < 1), and spinel-structured LiMn₂O₄.

[0120] In another embodiment, still in the case of forming a positive electrode for a lithium-ion secondary battery, the electroactive material may include an electroactive material based on lithiated or partially lithiated transition metal oxyanions having the formula M₁M₂(JO₄) f E 1-f where M₁ is lithium, which may be partially replaced by another alkali metal of less than 20% of the M₁ metal; M₂ is a transition metal selected from Fe, Mn, Ni, or a mixture thereof at an oxidation level of +2, which may be partially replaced by one or more additional metals that are at an oxidation level between +1 and +5 and account for less than 35% of the M₂ metal; JO₄ is any oxyanion, where J is P, S, V, Si, Nb, Mo, or a combination thereof; E is a fluoride anion, a hydroxide anion, or a chloride anion; and f is the mole fraction of the JO₄ oxyanion, generally included between 0.75 and 1.

[0121] M₁M₂(JO₄) as defined above f E 1-f The electroactive material is preferably phosphate-based and may have an ordered or modified olivine structure.

[0122] More preferably, in the case of forming a positive electrode, the electroactive material has the formula Li 3-x M’y M” 2-y (JO4)3, where 0 ≤ x ≤ 3, 0 ≤ y ≤ 2; M' and M" are the same or different metals, at least one of which is a transition metal; JO4 is preferably PO4, which may be partially substituted with another oxygen anion, wherein J is either S, V, Si, Nb, Mo, or a combination thereof. More preferably, the electroactive material is of the formula Li(Fe)3. x Mn 1-x Phosphate-based electroactive materials of PO4, wherein 0 ≤ x ≤ 1, and x is preferably 1 (i.e., lithium iron phosphate of formula LiFePO4).

[0123] In another embodiment, the electroactive material used for the positive electrode is selected from lithium-containing composite metal oxides of general formula (V).

[0124] LiNi x M1 y M2 z Y2 (V)

[0125] M1 and M2 may be the same or different from each other, and are transition metals selected from Co, Fe, Mn, Cr and V, 0.5≤x≤1, where y+z=1-x, and Y represents a chalcogenide element, preferably selected from O and S.

[0126] In this embodiment, the electroactive material is preferably a compound of formula (I), where Y is O. In a further preferred embodiment, M1 is Mn and M2 is Co, or M1 is Co and M2 is Al.

[0127] Examples of such active materials include LiNi x Mn y Co z O2 (hereinafter referred to as NMC) and LiNi x Co y Al z O2 (hereinafter referred to as NCA).

[0128] Especially for LiNi x Mn y Co z O2, by changing the ratio of manganese, nickel and cobalt content, can adjust the power and energy performance of the battery.

[0129] In a particularly preferred embodiment of the invention, the electroactive material is a compound having formula (V) as defined above, wherein 0.5 ≤ x ≤ 1, 0.1 ≤ y ≤ 0.5 and 0 ≤ z ≤ 0.5.

[0130] Non-limiting examples of suitable positive electrode electroactive materials having formula (I) noteworthy include:

[0131] LiNi 0.5 Mn 0.3 Co 0.2 O2;

[0132] LiNi 0.6 Mn 0.2 Co 0.2 O2;

[0133] LiNi 0.8 Mn 0.1 Co 0.1 O2;

[0134] LiNi 0.8 Co 0.15 Al 0.05 O2;

[0135] LiNi 0.8 Co 0.2 O2;

[0136] LiNi 0.8 Co 0.15 Al 0.05 O2;

[0137] LiNi 0.6 Mn 0.2 Co 0.2 O2

[0138] LiNi 0.8 Mn 0.1 Co 0.1 O 2,

[0139] LiNI 0,9 Mn 0,05 Co 0,05 O2.

[0140] Especially preferred compounds:

[0141] LiNi 0.8 Co 0.15 Al 0.05 O2;

[0142] LiNi 0.6 Mn 0.2 Co 0.2 O 2,

[0143] LiNi 0.8 Mn 0.1 Co 0.1 O 2,

[0144] LiNI 0,9 Mn0,05 Co 0,05 O2.

[0145] When forming the negative electrode of a lithium-ion secondary battery, the electroactive material may preferably include one or more carbon-based materials and / or one or more silicon-based materials.

[0146] In some embodiments, the carbon-based material may be selected from graphite (such as natural or artificial graphite), graphene, or carbon black.

[0147] These materials can be used alone or as a mixture of two or more of them.

[0148] Graphite is the preferred carbon-based material.

[0149] The silicon-based compound may be one or more selected from the group consisting of: chlorosilanes, alkoxysilanes, aminosilanes, fluoroalkylsilanes, silicon, silicon chloride, silicon carbide, and silicon oxide.

[0150] More specifically, the silicon-based compound can be silicon oxide and silicon carbide.

[0151] When present in an electroactive material, the silicon-based compound is included in the electroactive compound in an amount ranging from 1% to 60% by weight, preferably from 5% to 20% by weight, relative to the total weight of the electroactive compound.

[0152] According to the present invention, a "thermal initiator" is a substance that uses thermal energy to initiate a free radical cross-linking reaction.

[0153] The amount of thermal initiator in composition (C) is sufficient to cure the olefinic unsaturated component (Z) of the repeating unit (L) of the thermally assisted polymer (PA).

[0154] The concentration of the thermal initiator in composition (C) can be between 0.01 and 10 wt.%, based on the total weight of composition (C), for example between 0.1 and 5 wt.%, between 0.2 and 4 wt.%, or between 0.5 and 3 wt.%.

[0155] According to a preferred embodiment of the present invention, the thermal initiator is a low-temperature thermal initiator that can be cured at a temperature not exceeding 130°C.

[0156] Suitablely, the thermal initiator is selected from the group consisting of: free radical initiators, such as peroxides (organic and inorganic peroxides), persulfate and its salts, peresters and percarbonates, azonitrs and azo derivatives.

[0157] The preferred thermal initiator is selected from the group consisting of the following:

[0158] -Diacyl peroxide

[0159] - Benzoyl peroxide (BPO),

[0160] - Di-tert-butyl peroxide (DTBP)

[0161] - Cucurbitene hydroperoxide,

[0162] -Dicumyl peroxide

[0163] -tert-amyl hydroperoxide

[0164] -tert-amyl peroxybenzoate,

[0165] -4,4-Azobis(4-cyanovaleric acid),

[0166] -1,1'-azobis(cyclohexanenitrile),

[0167] -1,1'-azobis(cyclohexanenitrile),

[0168] - Benzoyl peroxide,

[0169] -2,2-bis(tert-butylperoxy)butane,

[0170] -1,1-bis(tert-butylperoxy)cyclohexanebenzene,

[0171] -2,5-bis(tert-butylperoxy)-2,5-dimethylhexane,

[0172] -2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne,

[0173] -bis(1-(tert-butylperoxy)-1-methylethyl)benzene,

[0174] -1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,

[0175] -tert-butyl hydroperoxide

[0176] -tert-butyl peracetate,

[0177] -Di-tert-butyl peroxide

[0178] - tert-butyl peroxide,

[0179] -tert-butylperoxyisopropyl carbonate

[0180] - Cucurbitene hydroperoxide,

[0181] Cyclohexanone peroxide,

[0182] -Dicumyl peroxide

[0183] -Lauroyl peroxide,

[0184] 2,4-Pentanedione peroxide

[0185] - Potassium persulfate,

[0186] -2,2'-Azobis(isobutyronitrile) (AIBN),

[0187] -Dimethyl 2,2'-azobis(2-methylpropionate),

[0188] -2,2'-Azobis[2-(2-imidazolin-2-yl)-propane] dihydrochloride,

[0189] -2,2'-Azobis(2-methyl-butyronitrile) (AMBN)

[0190] -2,2'-Azobis(2,4-dimethyl)pentanilonitrile,

[0191] -2,2'-Azobis(N-butyl-2-methylpropionamide),

[0192] -1,1'-azobis(cyclohexane-1-nitrile), and

[0193] -2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile).

[0194] According to a preferred embodiment of the present invention, the thermal initiator is a water-soluble thermal initiator capable of being dispersed in an aqueous medium. Preferred water-soluble thermal initiators may be selected from the group consisting of:

[0195] -2,2'-Azobis(2-methylpropanediamine) dihydrochloride

[0196] -2,2'-Azobis[N-(2-carboxyethyl)-2-methylpropanediamine]tetrahydrate

[0197] -2,2'-Azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride

[0198] -2,2'-Azobis[2-(2-imidazolin-2-yl)propane]

[0199] -2,2'-Azobis[2-methyl-N-(2-hydroxyethyl)propionamide]

[0200] -4,4'-Azobis(4-cyanovaleric acid)

[0201] -1,2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)-prop-2-yl)diazeline dihydrochloride.

[0202] According to a particularly preferred embodiment of the invention, the thermal initiator is 1,2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)-propyl-2-yl)diazeline dihydrochloride.

[0203] One or more optional conductive additives may be added to improve the conductivity of the resulting electrode made from the composition of the present invention. Conductive agents for batteries are known in the art.

[0204] Examples can include: carbon-containing materials, such as carbon black, finely powdered graphite, carbon nanotubes, graphene, or fibers, or finely powdered or fibrous metals (e.g., nickel or aluminum). The preferred conductive agent is carbon black. Carbon black is, for example, as described in the trademark Super or Available below.

[0205] When present, the conductive reagent differs from the carbon-based materials described above.

[0206] The amount of the optional conductive agent is preferably 0 to 30 wt.% of the total solids in the composition for forming the electrode. In particular, for the composition for forming the cathode, the optional conductive agent is typically 0 to 10 wt.% of the total solids in the composition, more preferably 0 to 5 wt.%.

[0207] For anode-forming compositions that do not contain silicon-based electroactive compounds, the optional conductive agent is typically from 0 to 5 wt.% of the total solids in the composition, more preferably from 0 to 2 wt.%. For anode-forming compositions that contain silicon-based electroactive compounds, it has been found advantageous to introduce a larger amount of the optional conductive agent, typically from 0.5 to 30 wt.% of the total solids in the composition.

[0208] The composition (C) for forming an electrode according to the present invention can be used in a method for manufacturing an electrode [electrode (E)], the method comprising:

[0209] (i) Provide a metal substrate having at least one surface;

[0210] (ii) Provide an electrode-forming composition as defined above [Composition (C)];

[0211] (iii) Applying the composition (C) provided in step (ii) to at least one surface of the metal substrate provided in step (i) to provide an assembly comprising a metal substrate having the composition (C) coated on at least one surface of the metal substrate;

[0212] (iv) Dry the component provided in step (iii);

[0213] (v) subject the dried component obtained in step (iv) to a compression step to obtain the electrode (E) of the present invention.

[0214] The metal substrate is typically a foil, mesh, or grid made of metal (such as copper, aluminum, iron, stainless steel, nickel, titanium, or silver).

[0215] In step (iii) of the method of the present invention, the electrode forming composition (C) is typically applied to at least one surface of a metal substrate by any suitable procedure such as casting, printing and roll coating.

[0216] Optionally, step (iii) can typically be repeated once or multiple times by applying the electrode forming composition (C) provided in step (ii) to the component provided in step (iv).

[0217] In step (iv) of the method of the present invention, drying can be carried out at atmospheric pressure or under vacuum. Alternatively, drying can be carried out in a modified atmosphere, such as in an inert gas, typically with notable removal of moisture (water vapor content less than 0.001% v / v).

[0218] A drying temperature will be selected so that the aqueous medium can be removed by evaporating it from the electrode (E) of the present invention.

[0219] In step (v), the dried component obtained in step (iv) is subjected to a compression step (such as a calendering process) to achieve the target porosity and density of the electrode (E) of the present invention.

[0220] Preferably, the dried component obtained in step (iv) is hot-pressed, and the temperature during the compression step ranges from 25°C to 130°C, preferably about 60°C.

[0221] The preferred target density of the electrode (E) is between 1.4 and 2 g / cc, preferably at least 1.55 g / cc. The density of the electrode (E) is calculated as the sum of the products of the densities of the electrode components and their mass ratios in the electrode formulation.

[0222] Without being bound by any theory, the inventors believe that during the drying step (iv), the composition (C) applied to at least one surface of the metal substrate undergoes curing.

[0223] In this document, "curing" refers to the process by which an irreversible cross-linked network (the so-called "cured form") is formed through the reaction of the olefinic unsaturated component Z of the repeating unit (L) of the polymer (PA), rendering the material no longer flowable, melting, or dissolving. In this document, the terms "curing," "curing," and "cross-linking" are used interchangeably.

[0224] It should be understood that the curing that begins in step (iv) of the method for preparing the electrode (E) can continue in step (v) of the method of the present invention for preparing the electrode (E).

[0225] The curing of the composition (C) of the present invention is carried out to some extent at low temperature during the duration of the drying and / or compression steps (iv) and (v).

[0226] The curing of the polymer (PA) in the composition (C) of the electrode (E) of the present invention can be verified by measuring the consumption of the olefinic unsaturated component, which is the result of measuring the peak area change of one or more peaks by Fourier transform infrared spectroscopy (FTIR), the peaks corresponding to the peaks at 1000 and 650 cm⁻¹. -1 Out-of-plane CH bending vibrations occur between them.

[0227] Advantageously, the polymer (PA) of the present invention is particularly suitable for curing in the presence of the aforementioned thermal initiator.

[0228] The applicant has unexpectedly discovered that the composition (C) contains the following:

[0229] - Polymers (PA) as defined above,

[0230] -At least one aqueous medium,

[0231] -At least one electroactive material,

[0232] - Thermal initiator and

[0233] -Optional, additives that impart conductivity.

[0234] For example, when subjected to heat treatment during the drying step (iv) and / or compression step (v), an electrode (E) characterized by improved adhesion to the metal current collector can be obtained.

[0235] In another aspect, the present invention relates to electrodes [electrodes (E)] that can be obtained by the method of the present invention.

[0236] Therefore, the present invention relates to an electrode (E) comprising:

[0237] - A metal substrate having at least one surface, and

[0238] - At least one layer directly adhered to at least one surface of the metal substrate, the layer comprising a composition including the following:

[0239] A) A water-soluble aromatic polyamic acid derivative [polymer (PA)], the polymer comprising:

[0240] a) at least 50 mol% of repeating unit (L), said repeating unit (L) comprising at least one acid moiety in the form of an ester;

[0241] b) 0 to 50 mol% of repeating unit (M), said repeating unit (M) comprising at least one acid moiety in the form of itself or an imide thereof;

[0242] c) 25 to 50 mol% of repeating unit (N), said repeating unit (N) comprising at least one acidic portion as a salt;

[0243] B) At least one electroactive material;

[0244] C) Optionally, an additive that imparts conductivity.

[0245] The composition that adheres directly to at least one surface of the metal substrate corresponds to the electrode forming composition (C) of the present invention, wherein the aqueous medium of the adhesive composition (B) has been at least partially removed during the electrode manufacturing process, for example in step (iv) (drying) and / or compression step (v). Therefore, all the preferred embodiments described with respect to the electrode forming composition (C) of the present invention also apply to compositions that adhere directly to at least one surface of the metal substrate in the electrode of the present invention, except for the aqueous medium removed during the manufacturing process.

[0246] In a preferred embodiment of the invention, the electrode (E) is a negative electrode. More preferably, the negative electrode comprises a silicon-based electroactive material.

[0247] The electrode (E) of the present invention is particularly suitable for electrochemical devices, especially for secondary battery packs.

[0248] The secondary battery of the present invention is preferably an alkali metal or alkaline earth metal secondary battery.

[0249] More preferably, the secondary battery of the present invention is a lithium-ion secondary battery.

[0250] The electrochemical device according to the present invention can be prepared by standard methods known to those skilled in the art.

[0251] If any patent, patent application, or disclosure incorporated herein by reference conflicts with the description of this application to the extent that it may lead to ambiguity in terminology, then this description shall take precedence.

[0252] The invention will now be described with reference to the following examples, which are merely illustrative and not intended to limit the scope of the invention.

[0253] Experimental Section

[0254] raw material

[0255] The silicon dioxide available commercially from Shin-Etsu Corporation as KSC-1064 has a theoretical capacity of approximately 2100 mAh / g;

[0256] Carbon black available from Imerys SA as SC45;

[0257] Graphite is commercially available from Imerys SA as ACTILION 2.

[0258] Carboxymethyl cellulose (CMC) is available from Nippon Paper as MAC 500HC;

[0259] From ZEON Corporation as BM-480B provides a styrene-butadiene rubber (SBR) suspension (38 wt.% in water);

[0260] Ethyl carbonate: dimethyl carbonate = 1:1 (by weight percentage) is available from BASF as Selectilyte™ LP 30;

[0261] Fluoroethyl carbonate (F1EC) is available from Sigma-Aldrich; and

[0262] Vinyl carbonate is available from Sigma-Aldrich.

[0263] 1,2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)propyl-2-yl)diazeline dihydrochloride (thermal initiator, hereinafter) is available from Sigma-Aldrich.

[0264] A solution of poly(4,4'-oxophenylene pyromellitic acid) (Kapton polyamic acid) available from Sigma-Aldrich in NMP (15-16 wt.%).

[0265] PMDA is available from Sigma-Aldrich.

[0266] 4,4'-Diaminodiphenyl ether (ODA) is available from Sigma-Aldrich.

[0267] Trimethylamine (TEA) is available from Sigma-Aldrich.

[0268] Anhydrous N-methyl-2-pyrrolidone (NMP) is available from Sigma-Aldrich.

[0269] Pyromellitic ester diacrylate dichlorophosphate (PADE-HEA-Cl Mw: 487.24 g / mol) was synthesized according to the method reported in the literature. For specific reference, see Hedge et al.'s "3D Printing All-Aromatic Polyimides using Mask-Projection Stereolithography: Processing the Nonprocessable" (Adv. Mater. 2017, 29).

[0270] General procedure for determining molecular weight (Mn, Mw, Mz, and Mz+1)

[0271] Molecular weight was determined by gel permeation chromatography (GPC) using N,N-dimethylformamide as the mobile phase. Separation was performed using two 5 μm mixed-D columns from Agilent Technologies with guard columns. Chromatograms were obtained using a 254 nm UV detector. A flow rate of 1.5 mL / min and an injection volume of 20 μL of 0.2 w / v solution in the mobile phase were selected. Calibration was performed using 12 narrow molecular weight polystyrene standards (peak molecular weight range: 371,000 g / mol to 580 g / mol). Number-average molecular weight Mn, weight-average molecular weight Mw, higher average molecular weight Mz, and Mz+1 are reported.

[0272] Preparation 1: Polymer A prepared according to the synthesis procedure in Scheme 1

[0273]

[0274] 49.83 g ODA, 27.26 g TEA, and 750 mL anhydrous NMP were added to a 1 L round-bottom flask equipped with a nitrogen inlet / outlet, thermocouple, and mechanical stirrer. After the ODA dissolved, the solution was cooled to -5.0 °C. 27.27 g (PMDA) and 27.42 g (PADE-HEA-Cl) were added in portions to the solution over 1.5 h, while maintaining the solution temperature below 0 °C. After the addition was complete, 100 mL of anhydrous NMP was added to the mixture, and the mixture was kept at 0 °C for 3 h. The solution was then drained and condensed in 3 L of water using a Warring stirrer. The precipitated polymer was collected by vacuum filtration and washed three times with 3 L of methanol. After washing, the powder was dried under reduced pressure (25 inHg) at 35 °C for 48 h, yielding 119 g of pale yellow powder. The molecular weight of polymer A was calculated. The results are summarized in Table 1.

[0275] Preparation 2: Polymer C

[0276] A 1-liter solution (15-16 wt.%) of Kapton polyamic acid in NMP was coagulated in 3 L of deionized water using a Warring stirrer. The resulting yellow precipitate was collected by vacuum filtration and washed with 2 L of boiling water, followed by 2 L of methanol. The yellow powder was dried under reduced pressure (25 inHg vacuum) at 40 °C for 5 days to yield 154 g of pale yellow powder. The molecular weight of polymer C was calculated. The results are summarized in Table 1.

[0277] Table 1

[0278] <![CDATA[ Mw ]]> <![CDATA[ Mn ]]> <![CDATA[ Mw / Mn ]]> <![CDATA[ Mz ]]> <![CDATA[ Mz+1 ]]> <![CDATA[ Mz / Mw ]]> Polymer A 4539 37600 8.28 84600 133406 2.25 Polymer C 20733 44155 2.13 65965 82449 3.18

[0279] Preparation 3: Adhesive composition comprising a lithium-ionized water-soluble aromatic polyamic acid derivative solution

[0280] Pour 91 mL of deionized water into a flask equipped with a magnetic stirrer. Add the required amount of lithium carbonate (1.3 g) and heat the solution to 50°C. While stirring vigorously, add 8.3 g of the polymer A powder obtained above. After adding all the polymer to the flask, continue heating for 5 days, then drain the homogenized solution. This yields a solution with an 8.3 wt.% concentration in water.

[0281] Preparation 4: Adhesive composition comprising a lithium-ionized water-soluble aromatic polyamic acid solution

[0282] Pour 90 mL of deionized water into a flask equipped with a magnetic stirrer. Add the required amount of lithium carbonate (1.3 g) and heat the solution to 50 °C. While stirring vigorously, add the polymer C powder (9 g) obtained above. After all the polymer has been added to the flask, continue heating for 3 days, then drain the homogenized solution. This yields a 9 wt.% solution in water.

[0283] A general procedure for preparing compositions for forming electrodes and negative electrodes.

[0284] The following details the preparation of the electrode composition and negative electrode using the following equipment:

[0285] Mechanical mixers: planetary mixers (Speedmixer) and mixers with flat PTFE lightweight dispersing impellers. A series of mechanical mixers;

[0286] Film coater / scraper: 4340 motorized / automatic membrane applicator;

[0287] Vacuum Oven: BINDER APT line VD 53 with vacuum; and

[0288] Roller press: Precision 4” hot roller press / calender with a maximum temperature of 100°C.

[0289] Example 1: Preparation of a negative electrode containing lithium polymer A

[0290] An aqueous composition was prepared by mixing 33.13 g of the lithium-ionized polymer A obtained in Preparation 3 with an 8.3 wt.% solution in 14.62 g of deionized water, 10.34 g of silica, 41.36 g of graphite, and 0.55 g of carbon black. The mixture was homogenized by gentle stirring in a planetary mixer for 10 min, and then mixed again by gentle stirring for 2 h.

[0291] The negative electrode was obtained by casting the thus-obtained electrode onto an 18.5 μm thick copper foil using a doctor blade and drying the coating in an oven at 60°C for approximately 60 minutes. The thickness of the dried coating was approximately 65 μm. The electrode was then hot-pressed in a roller press at 60°C to achieve a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8 wt.% silicon dioxide, 75.2 wt.% graphite, 5 wt.% polymer A, and 1 wt.% carbon black.

[0292] Electrode E1 was thus prepared.

[0293] Example 2: Preparation of a negative electrode containing lithium polymer A and a thermal initiator

[0294] An aqueous composition was prepared by mixing 33.13 g of an 8.3 wt.% solution of the lithium polymer A obtained in Preparation 4 in water, 14.62 g of deionized water, 10.34 g of silica, 41.36 g of graphite, 0.55 g of carbon black, and 0.05 g of 1,2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)propyl-2-yl)diazeline dihydrochloride. The mixture was homogenized by gentle stirring in a planetary mixer for 10 min, and then mixed again by gentle stirring for 2 h.

[0295] The negative electrode was obtained by casting the thus-obtained electrode onto an 18.5 μm thick copper foil using a doctor blade and drying the coating in an oven at 60°C for approximately 60 minutes. The thickness of the dried coating was approximately 64 μm. The electrode was then hot-pressed in a roller press at 60°C to achieve a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8 wt.% silicon dioxide, 75.2 wt.% graphite, 5 wt.% polymer A, and 1 wt.% carbon black.

[0296] Electrode E2 is therefore prepared.

[0297] Comparative Example 1: Negative Electrode Containing Lithium-Ionized Polymer C

[0298] An aqueous composition was prepared by mixing 30.56 g of a 9 wt.% solution of polymer C obtained in Preparation 2 in water, 17.19 g of deionized water, 10.34 g of silica, 41.36 g of graphite, and 0.55 g of carbon black. The mixture was homogenized by gentle stirring in a planetary mixer for 10 min, and then mixed again by gentle stirring for 2 h.

[0299] The negative electrode was obtained by casting the binder composition thus obtained onto an 18.5 μm thick copper foil using a doctor blade and drying the coating in an oven at 60°C for approximately 60 minutes. The thickness of the dried coating was approximately 60 μm. The electrode was then hot-pressed in a roller press at 60°C to achieve a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8 wt.% silicon dioxide, 75.2 wt.% graphite, 5 wt.% polymer C, and 1 wt.% carbon black.

[0300] Electrode CE1 is thus obtained.

[0301] Comparative Example 2: Negative Electrode Including SBR / CMC

[0302] An aqueous composition was prepared by mixing 35.0 g of a solution of 2% CMC in water, 21.41 g of deionized water, 7.90 g of silica, 31.58 g of graphite and 0.42 g of carbon black.

[0303] The mixture was homogenized by gently stirring in a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour.

[0304] After mixing for about 1 hour, 3.69 g of SBR suspension was added to the composition and mixed again for 1 hour with low stirring.

[0305] The negative electrode was obtained by casting the binder composition thus obtained onto an 18.5 μm thick copper foil using a doctor blade and drying the coating in an oven at 90°C for approximately 70 minutes. The thickness of the dried coating was approximately 62 μm. The electrode was then hot-pressed in a roller press at 60°C to achieve a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8 wt.% silicon oxide, 75.2 wt.% graphite, 3 wt.% SBR, 2% CMC, and 1 wt.% carbon black. Electrode CE2 was thus obtained.

[0306] Measurement of the adhesion properties of the negative electrode

[0307] Peel tests were performed on electrodes (E1), (E2), (CE1), and (CE2) at 300 mm / min and 20°C according to the following standard ASTM D903 to evaluate the adhesion of the electrode composition coating to the metal foil.

[0308] The results are shown in Table 1.

[0309] Table 1

[0310] electrode Adhesion force (N / m) E1 5 E2 10 CE1 14 CE2 55

[0311] Battery manufacturing

[0312] Lithium button batteries (CR2032 type, 20 mm diameter) were fabricated in a glove box under an Ar atmosphere by punching small discs (diameter = 12 mm) of electrodes prepared using the compositions of Examples 1, 2, Comparative Examples 1 and 2, with lithium metal serving as a reference electrode.

[0313] The electrolyte used to prepare the coin cell is a standard 1M LiPF6 solution in a 1 / 1 ratio EC / DMC with 10 wt.% F1EC and 2 wt.% VC additive.

[0314] Use polyethylene diaphragms as received (commercially available from Tonen Chemical Corporation).

[0315] Half-cell capacity retention test

[0316] After initial charge and discharge cycles at low current rates (phase formation), each of the two battery cells prepared as described in Examples 1, 2, Comparative Examples 1 and 2 is constant-current cyclic at a constant current rate of C / 5-D / 5, with a positive cutoff of 1.5V and a negative cutoff of 0.05V.

[0317] The obtained data is reported in Table 2.

[0318] Table 2

[0319]

[0320]

[0321] Batteries were prepared based on Example 1 and Example 2, which showed acceptable coulombic efficiency, good initial capacity and good retention after 25 cycles.

[0322] Advantageously, compared with electrodes of the prior art, the electrodes prepared according to the present invention exhibit a better trade-off between adhesion to the current collector and battery performance.

Claims

1. A water-soluble aromatic polyamic acid derivative for use in battery electrodes, comprising: a) At least 50 mol% of repeating unit L, said repeating unit L comprising at least one acid moiety in the form of an ester; b) 0 to 50 mol% of repeating unit M, wherein the repeating unit M comprises at least one acid moiety in the form of itself or an imide thereof; c) 25 to 50 mol% of repeating unit N, wherein the repeating unit N comprises at least one acidic portion as a salt; in, The repeating unit L is selected from a group of units that have any one of the terms of the general formula L1 to L4: ； The repeating unit M is selected from a group of units that have any one of the terms of the general formula M1 to M4: ； The repeating unit N is selected from a group of units that have any one of the terms of the general formula N1 to N4: ； in - Ar is a trivalent aromatic moiety that is selected from the group consisting of substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms. - Ar' is a tetravalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms. - Each R1 is independently H or an alkyl group having 1 to 5 carbon atoms; - R is selected from the following groups: and the corresponding optionally substituted structures wherein Y is selected from the group consisting of -0-, -S-, -S02-, -CH2-, -C(O)-, -C(CF3)2-, -(CF2) p - "p" is an integer from 0 to 5, - Each Z is independently selected from the following groups: • O-(CH2) k O-CO-CH=CHR4, wherein k is from 1 to 20; and R4is H or an alkyl group having 1 to 5 carbon atoms; • O-(CH2) p -Ar-CR5 = CHR6 or O-(CH2) p -OAr-CR5=CHR6, where p is 0 to 20; Ar contains one or two aromatic or heteroaromatic rings; R5 and R6 are H or alkyl, phenyl or COOR7 having 1 to 5 carbon atoms, where R7 is H or alkyl having 1 to 5 carbon atoms; • O-(CH2) q -CH=CHR8 where q is from 0 to 20; and R8 is H or an alkyl group having 1 to 5 carbon atoms; O-(CH2) r -O-CH=CHR9 where r is from 0 to 20; and R9 is H or an alkyl group having 1 to 5 carbon atoms; and - Cat + It is Li + .

2. The water-soluble aromatic polyamic acid derivative according to claim 1, wherein R is: 。 3. The water-soluble aromatic polyamic acid derivative according to claim 1, wherein each Z is independently selected from the group consisting of: O-(CH2) k -O-CO-CH=CHR4, where k is from 1 to 8; and R4 is H or an alkyl group having 1 to 5 carbon atoms; O-(CH2) p -Ar-CR5 = CHR6 or O-(CH2) p -OAr-CR5=CHR6, where p is from 1 to 8; Ar contains one or two aromatic or heteroaromatic rings; R5 and R6 are H or alkyl, phenyl or COOR7 having 1 to 5 carbon atoms, where R7 is H or alkyl having 1 to 5 carbon atoms; O-(CH2) q -CH=CHR8 where q is from 1 to 8; and R8 is H or an alkyl group having 1 to 5 carbon atoms; O-(CH2) r -O-CH=CHR9 where r is from 1 to 8; and R9 is H or an alkyl group having 1 to 5 carbon atoms.

4. The water-soluble aromatic polyamic acid derivative according to claim 1, wherein each Z is independently selected from the group consisting of: O-(CH2) k -O-CO-CH=CHR4, where k is from 2 to 6; and R4 is H or an alkyl group having 1 to 5 carbon atoms.

5. The water-soluble aromatic polyamic acid derivative according to claim 1, wherein each Z is independently selected from the group consisting of: O-(CH2) k -O-CO-CH=CHR4, where k equals 2 or 3; and R4 is H or an alkyl group having 1 to 5 carbon atoms.

6. The water-soluble aromatic polyamic acid derivative according to claim 1, comprising: a) A group of repeating units consisting of at least 50 mol% of units selected from any one of the terms of general formula L2 or L4; b) Repeating units of a group consisting of 0 to 50 mol% of any one of the terms of general formula M2 or M4; c) A group of repeating units consisting of 25 to 50 mol% of units selected from any one of the general formulas N2 or N4.

7. An aqueous binder composition for a battery electrode, comprising a water-soluble aromatic polyamic acid derivative according to any one of claims 1 to 6 and at least one aqueous solvent.

8. The aqueous adhesive composition according to claim 7, wherein the aqueous solvent is water.

9. A composition for forming an electrode, comprising: (i) The aqueous adhesive composition according to claim 7 or 8; (ii) At least one electroactive material; (iii) Optionally, a thermal initiator; and (iv) Optionally, an additive that imparts conductivity.

10. The composition for forming an electrode according to claim 9, wherein, The electroactive material includes one or more carbon-based materials and / or one or more silicon-based materials.

11. The composition for forming an electrode according to claim 10, wherein, The thermal initiator is 1,2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)-propyl-2-yl)diazeline dihydrochloride.

12. The composition for forming an electrode according to any one of claims 9 to 11, comprising: (A) The aqueous adhesive composition according to claim 7 or 8; (B) At least one electroactive material selected from one or more carbon-based materials and / or one or more silicon-based materials; (C) A thermal initiator, which is 2-bis(2-(4,5-dihydro-1H-imidazol-2-yl)-propyl-2-yl)diazeline dihydrochloride; and (D) Optionally, an additive that imparts conductivity.

13. Use of the composition for forming electrodes according to any one of claims 9 to 12 for manufacturing electrodes.

14. A method for manufacturing an electrode, the method comprising: (i) A metal substrate having at least one surface is provided; (ii) Providing a composition for forming an electrode according to any one of claims 9-12; (iii) The electrode-forming composition provided in step (ii) is applied to at least one surface of the metal substrate provided in step (i) to provide an assembly comprising a metal substrate on which at least one surface is coated with the electrode-forming composition. (iv) Dry the component provided in step (iii); (v) subject the dried component obtained in step (iv) to a compression step to obtain an electrode.

15. An electrode obtainable by the method according to claim 14.

16. An electrochemical device comprising at least one electrode according to claim 15.

17. The electrochemical device according to claim 16, wherein the electrochemical device is a secondary battery pack comprising: - Positive electrode and negative electrode, At least one of the positive electrode and the negative electrode is the electrode according to claim 15.

18. The electrochemical device according to claim 16, wherein the electrochemical device is a secondary battery pack comprising: - Positive electrode and negative electrode, The negative electrode is the electrode according to claim 15.

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