Electrolyte compositions comprising oligomeric silylphosphonates

Abstract

The present invention relates to an electrolyte composition, which contains (i) at least one aprotic organic solvent; (ii) at least one conductive salt; (iii) at least one silylphosphonate containing the structure of formula (I), wherein T is selected from (Ia) and (Ib); and (iv) optionally one or more additives.

Description

[0001] describe

[0002] The present invention relates to an electrolyte composition comprising a silyl phosphonate having a structure of formula (I), use of the silyl phosphonate having a structure of formula (I) in an electrolyte composition for an electrochemical cell, and an electrochemical cell comprising the electrolyte composition:

[0003]

[0004] Where R 3 and T are defined below.

[0005] Storing electrical energy is a topic of growing interest. Storing electrical energy efficiently allows the generation of electrical energy when it is advantageous and the use of electrical energy when it is needed. Secondary electrochemical cells are very suitable for this purpose due to their reversible conversion of chemical energy to electrical energy and vice versa (rechargeability). Secondary lithium batteries are particularly interesting for energy storage because they provide high energy density and specific energy due to the small atomic weight of lithium ions compared to other battery systems and can obtain high cell voltages (typically 3-5V). For this reason, these systems are widely used as power sources for many portable electronic products such as mobile phones, laptops, miniature cameras, etc.

[0006] In secondary lithium batteries such as lithium ion batteries, organic carbonates, ethers, esters and ionic liquids are used as polar solvents sufficient to solvate the conducting salts. Most prior art lithium ion batteries typically do not contain a single solvent but a solvent mixture of different organic aprotic solvents.

[0007] In addition to solvents and conductive salts, the electrolyte composition usually contains other additives to improve certain properties of the electrolyte composition and the electrochemical cell containing the electrolyte composition. Common additives are, for example, flame retardants, overcharge protection additives and film-forming additives that react on the electrode surface during the first charge / discharge cycle and thereby form a film on the electrode. Different Si- and / or P-containing additives are known for use in electrolyte compositions.

[0008] No. 8,734,668 B2 describes electrolyte compositions comprising silicon-containing compounds which may additionally contain heteroatoms such as B, Al, P, S, F, Cl, Br and I.

[0009] EP 2 573 854 A1 discloses an electrolyte composition for lithium ion batteries, which contains a phosphonic acid derivative containing a silyl ester group to suppress an increase in battery resistance and a deterioration in battery performance in a high temperature environment.

[0010] US 2013 / 0164604 A1 relates to the use of phosphites, phosphonates and bisphosphonates as additives in electrolyte compositions for lithium-ion batteries.

[0011] In order to improve the performance of lithium batteries, new cathode active materials are used. These cathode active materials have higher specific energy and / or higher operating voltage. Examples of such cathode active materials are high-energy NCM (lithium-substituted mixed oxides of Ni, Co and Mn, so-called HE-NCM), high-voltage manganese spinel and lithium nickel cobalt aluminum oxide (also referred to as NCA) with a layered structure containing additional transition metals. For some of these cathode active materials, a high cut-off voltage must be used during the charging process to obtain the required high specific energy. These cathode active materials impose new requirements on the electrolyte composition used, for example, in terms of stability to high voltage, O2 release, solvation of transition metal cations that cause metal dissolution, gas evolution during storage, etc.

[0012] There remains a need to improve the performance of electrochemical cells, especially those comprising the above-mentioned cathode materials, for example in terms of high capacity retention, good long-term performance, high safety, reduced gas evolution and reduced impedance buildup.

[0013] The object of the present invention is to provide an additive for use in an electrochemical cell to improve the performance of the electrochemical cell, for example with respect to high capacity retention, good long-term performance, high safety, reduced gas evolution and reduced impedance accumulation. In particular, additives should be provided to improve the performance of an electrochemical cell comprising a cathode active material having a high specific energy and / or a high operating voltage. Another object of the present invention is to provide an electrolyte composition for an electrochemical cell, the resulting electrochemical cell having a high capacity retention, good long-term performance and high safety. In particular, an electrolyte composition for a cathode active material having a high specific energy and / or a high operating voltage should be provided. The object of the present invention is also to provide an electrochemical cell showing high capacity retention, good long-term performance, high safety, reduced gas evolution and reduced impedance accumulation.

[0014] Therefore, an electrolyte composition is provided, which contains

[0015] (i) at least one aprotic organic solvent;

[0016] (ii) at least one conductive salt;

[0017] (iii) at least one silylphosphonate having the structure of formula (I):

[0018]

[0019] in

[0020] T is selected from

[0021] p is an integer from 0 to 6 and one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl;

[0022] R 1 is independently selected at each occurrence from H, F, Cl, R 4 , OR 4 、OSi(R 5 )3、OSi(OR 4 )3 and OP(O)(OR 4 )R 5 ;

[0023] R 4 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to a Si atom or an O atom may be replaced by O;

[0024] R 3 and R 5 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the P atom may be replaced by O; and

[0025] (iv) optionally one or more additives.

[0026] Additionally, the use of silylphosphonates containing units of formula (I) in electrochemical cells is provided, for example as additives in electrolyte compositions for electrochemical cells and electrochemical cells comprising said electrolyte compositions. The electrochemical cells of the present invention exhibit good capacity retention, good long-term performance, reduced cell resistance and reduced gas generation during storage at elevated temperatures. Silylphosphonates containing units of formula (I) are non-volatile under conditions during preparation, storage and use of electrochemical cells, which facilitates handling and storage of the electrolyte composition.

[0027] The present invention is described in detail below.

[0028] Chemically, an electrolyte composition is any composition that contains free ions and is therefore electrically conductive. The electrolyte composition serves as a medium for the transfer of ions that participate in the electrochemical reactions that occur in an electrochemical cell. In the case of lithium batteries, the ions that participate in the electrochemical reactions are usually lithium ions. The most common electrolyte compositions are ionic solutions, but molten electrolyte compositions and solid electrolyte compositions are likewise possible. The electrolyte composition of the invention is therefore a conductive medium, primarily due to the presence of at least one substance that is present in a dissolved and / or molten state, i.e. the conductivity is supported by the movement of ionic species. In liquid or gel electrolyte compositions, the conductive salt is usually solvated in one or more aprotic organic solvents.

[0029] The electrolyte composition contains at least one aprotic organic solvent (i). The at least one aprotic organic solvent may be selected from optionally fluorinated aprotic organic solvents, i.e. fluorinated and non-fluorinated aprotic organic solvents. The electrolyte composition may contain a mixture of fluorinated and non-fluorinated aprotic organic solvents.

[0030] The aprotic organic solvent is preferably selected from the group consisting of optionally fluorinated cyclic and acyclic organic carbonates, optionally fluorinated acyclic ethers and polyethers, optionally fluorinated cyclic ethers, optionally fluorinated cyclic and acyclic acetals and ketals, optionally fluorinated orthocarboxylates, optionally fluorinated cyclic and acyclic esters and diesters of carboxylic acids, optionally fluorinated cyclic and acyclic sulfones, optionally fluorinated cyclic and acyclic nitriles and dinitriles and optionally fluorinated cyclic and acyclic phosphates and mixtures thereof.

[0031] Examples of optionally fluorinated cyclic carbonates are ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC), wherein one or more H may be substituted by F and / or C1-C4 alkyl, such as 4-methylethylene carbonate, fluoroethylene carbonate (FEC) and cis- and trans-difluoroethylene carbonate. Preferred optionally fluorinated cyclic carbonates are ethylene carbonate, fluoroethylene carbonate and propylene carbonate, especially ethylene carbonate.

[0032] Examples of optionally fluorinated acyclic carbonates are di-C1-C 10 Alkyl esters, wherein the alkyl groups are selected independently of one another and wherein one or more H may be substituted by F. Preference is given to optionally fluorinated di-C1-C4 alkyl carbonates. Examples are, for example, diethyl carbonate (DEC), ethyl methyl carbonate (EMC), 2,2,2-trifluoroethyl methyl carbonate (TFEMC), dimethyl carbonate (DMC), trifluoromethyl methyl carbonate (TFMMC) and methyl propyl carbonate. Preferred acyclic carbonates are diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC).

[0033] In one embodiment of the present invention, the electrolyte composition contains a mixture of optionally fluorinated acyclic organic carbonate and cyclic organic carbonate in a weight ratio of 1:10 to 10:1, preferably 3:1 to 1:1.

[0034] Examples of optionally fluorinated acyclic ethers and polyethers are optionally fluorinated di-C1-C 10 Alkyl ethers, optionally fluorinated di-C1-C4 alkyl-C2-C6 alkylene ethers, optionally fluorinated polyethers and compounds of the formula R'-(O-CF r H 2-r ) q -R" fluoroether, wherein R' is C1-C 10 Alkyl or C3-C 10 Cycloalkyl, wherein one or more H of the alkyl and / or cycloalkyl is replaced by F; R" is H, F, C1-C 10 Alkyl or C3-C 10 Cycloalkyl, wherein one or more H of the alkyl and / or cycloalkyl is substituted with F; r is 1 or 2; and q is 1, 2 or 3.

[0035] According to the present invention, the optionally fluorinated di-C1-C 10 The alkyl groups of the alkyl ether are selected independently of one another, wherein one or more H of the alkyl group may be substituted by F. 10 Examples of alkyl ethers are dimethyl ether, ethyl methyl ether, ethyl ether, methyl propyl ether, diisopropyl ether, di-n-butyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CF2HCF2CH2OCF2CF2H) and 1H,1H,5H-perfluoropentyl-1,1,2,2-tetrafluoroethyl ether (CF2H(CF2)3CH2OCF2CF2H).

[0036] Examples of optionally fluorinated di-C1-C4-alkyl-C2-C6-alkylene ethers are 1,2-dimethoxyethane, 1,2-diethoxyethane, diglyme (diethylene glycol dimethyl ether), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (tetraethylene glycol dimethyl ether) and diethylene glycol diethyl ether.

[0037] Examples of suitable optionally fluorinated polyethers are polyalkylene glycols, preferably poly-C1-C4-alkylene glycols, especially polyethylene glycols, in which one or more H of the alkyl or alkylene radicals may be replaced by F. The polyethylene glycol may contain up to 20 mol % of one or more C1-C4-alkylene glycols in copolymerized form. The polyalkylene glycol is preferably a dimethyl- or diethyl-terminated polyalkylene glycol. The molecular weight M of suitable polyalkylene glycols, especially suitable polyethylene glycols, is wThe molecular weight M of suitable polyalkylene glycols, in particular suitable polyethylene glycols, may be at least 400 g / mol. w It may be at most 5 000 000 g / mol, preferably at most 2 000 000 g / mol.

[0038] Formula R'-(O-CF p H 2-p ) q Examples of fluoroethers of -R" are 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CF2HCF2CH2OCF2CF2H) and 1H,1H,5H-perfluoropentyl-1,1,2,2-tetrafluoroethyl ether (CF2H(CF2)3CH2OCF2CF2H).

[0039] Examples of optionally fluorinated cyclic ethers are 1,4-difluoro- alkanes, tetrahydrofuran and its derivatives such as 2-methyltetrahydrofuran, wherein one or more H of the alkyl group may be replaced by F.

[0040] Examples of optionally fluorinated acyclic acetals are 1,1-dimethoxymethane and 1,1-diethoxymethane. Examples of cyclic acetals are 1,3-dimethoxymethane and 1,1-diethoxymethane. Alkanes, 1,3-dioxolane and its derivatives such as methyldioxolane, in which one or more H may be replaced by F.

[0041] Examples of optionally fluorinated acyclic orthocarboxylates are triC1-C4alkoxymethanes, in particular trimethoxymethane and triethoxymethane. Examples of suitable cyclic orthocarboxylates are 1,4-dimethyl-3,5,8-trioxabicyclo[2.2.2]octane and 4-ethyl-1-methyl-3,5,8-trioxabicyclo[2.2.2]octane, in which one or more H may be replaced by F.

[0042] Examples of acyclic esters of optionally fluorinated carboxylic acids are ethyl and methyl formate, ethyl and methyl acetate, ethyl and methyl propionate and ethyl and methyl butyrate, and esters of dicarboxylic acids, such as dimethyl 1,3-malonate, in which one or more H may be replaced by F. An example of a cyclic ester (lactone) of a carboxylic acid is γ-butyrolactone.

[0043] Examples of optionally fluorinated cyclic and acyclic sulfones are ethylmethylsulfone, dimethylsulfone and tetrahydrothiophene-S,S-dioxide (sulfolane).

[0044] Examples of optionally fluorinated cyclic and acyclic nitriles and dinitriles, in which one or more H may be replaced by F, are adiponitrile, acetonitrile, propionitrile and butyronitrile.

[0045] Examples of optionally fluorinated cyclic and acyclic phosphates are trialkyl phosphates in which one or more H of the alkyl group may be substituted by F, such as trimethyl phosphate, triethyl phosphate and tris(2,2,2-trifluoroethyl) phosphate.

[0046] More preferably, the aprotic organic solvent is selected from the group consisting of optionally fluorinated ethers and polyethers, optionally fluorinated cyclic and acyclic organic carbonates, optionally fluorinated cyclic and acyclic esters and diesters of carboxylic acids, and mixtures thereof. Even more preferably, the aprotic organic solvent is selected from the group consisting of optionally fluorinated ethers and polyethers and optionally fluorinated cyclic and acyclic organic carbonates, and mixtures thereof.

[0047] According to one embodiment, the electrolyte composition contains at least one solvent selected from fluoroethers and polyethers, for example a compound of the formula R'-(O-CF p H 2-p ) q -R" fluoroether, such as CF2HCF2CH2OCF2CF2H or CF2H(CF2)3CH2OCF2CF2H.

[0048] According to another embodiment, the electrolyte composition contains at least one solvent selected from fluorinated cyclic carbonates, such as 1-fluoroethyl carbonate.

[0049] According to another embodiment, the electrolyte composition contains at least one solvent selected from fluorinated cyclic carbonates, such as 1-fluoroethyl carbonate, and at least one solvent selected from fluorinated ethers and polyethers, for example, a compound of the formula R'-(O-CF r H 2-r ) s -R" fluoroether, such as CF2HCF2CH2OCF2CF2H or CF2H(CF2)3CH2OCF2CF2H.

[0050] According to another embodiment, the electrolyte composition contains at least one fluorinated cyclic carbonate, such as 1-fluoroethyl carbonate, and at least one non-fluorinated acyclic organic carbonate, such as dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate.

[0051] The electrolyte composition contains at least one conductive salt (ii). The electrolyte composition is used as a medium for transferring ions participating in the electrochemical reaction occurring in the electrochemical cell. The conductive salt (ii) present in the electrolyte composition is usually solvated in an aprotic organic solvent (i). Preferably, at least one conductive salt (ii) is selected from lithium salts. Examples of lithium ion-containing conductive salts are:

[0052] ·Li[F 6-x P(C y F 2y+1 ) x], wherein x is an integer from 0 to 6 and y is an integer from 1 to 20; Li[B(R I )4]、Li[B(R I )2(OR II O)] and Li[B(OR II O)2], where R I Each independently selected from F, Cl, Br, I, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, OC1-C4 alkyl, OC2-C4 alkenyl and OC2-C4 alkynyl, wherein alkyl, alkenyl and alkynyl may be substituted by one or more OR III Substitution, where R III is selected from C1-C6 alkyl, C2-C6 alkenyl and C2-C6 alkynyl, and (OR II O) is a divalent radical derived from a 1,2- or 1,3-diol, a 1,2- or 1,3-dicarboxylic acid or a 1,2- or 1,3-hydroxycarboxylic acid, wherein the divalent radical forms a 5- or 6-membered ring with the central B atom via the two oxygen atoms;

[0053] LiClO4, LiAsF6, LiCF3SO3, Li2SiF6, LiSbF6, LiAlCl4, Li(N(SO2F)2), lithium tetrafluoro(oxalato)phosphate, lithium oxalate; and

[0054] ·General formula Li[Z(C n F 2n+1 SO2) m ], wherein m and n are as defined below:

[0055] When Z is selected from oxygen and sulfur, m=1,

[0056] When Z is selected from nitrogen and phosphorus, m=2,

[0057] When Z is selected from carbon and silicon, m=3, and

[0058] n is an integer of 1-20.

[0059] Derived divalent group (OR II Suitable 1,2- and 1,3-diols of the present invention may be aliphatic or aromatic and may be selected, for example, from 1,2-dihydroxybenzene, 1,2-propylene glycol, 1,2-butylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, trans-1,2-cyclohexanediol and 2,3-naphthalene diol, which are optionally substituted with one or more F and / or at least one non-fluorinated, partially fluorinated or fully fluorinated linear or branched C1-C4 alkyl radical. An example of such 1,2- or 1,3-diols is 1,1,2,2-tetrakis(trifluoromethyl)-1,2-ethanediol.

[0060] The term "fully fluorinated C1-C4 alkyl group" means that all H atoms of the alkyl group are replaced by F.

[0061] Derived divalent group (OR II Suitable 1,2- or 1,3-dicarboxylic acids of O) may be aliphatic or aromatic, for example oxalic acid, malonic acid (1,3-malonic acid), phthalic acid or isophthalic acid, preferably oxalic acid. The 1,2- or 1,3-dicarboxylic acids are optionally substituted with one or more F and / or at least one non-fluorinated, partially fluorinated or fully fluorinated linear or branched C1-C4 alkyl group.

[0062] Derived divalent group (OR II Suitable 1,2- or 1,3-hydroxycarboxylic acids of (O) may be aliphatic or aromatic, such as salicylic acid, tetrahydrosalicylic acid, malic acid and 2-hydroxyacetic acid, optionally substituted with one or more F and / or at least one non-fluorinated, partially fluorinated or fully fluorinated linear or branched C1-C4 alkyl group. An example of such 1,2- or 1,3-hydroxycarboxylic acids is 2,2-bis(trifluoromethyl)-2-hydroxyacetic acid.

[0063] Li[B(R I )4]、Li[B(R I )2(OR II O)] and Li[B(OR II Examples of [0)2] are LiBF4, lithium difluorooxalatoborate and lithium dioxalatoborate.

[0064] Preferably, the at least one lithium ion-containing conductive salt is selected from LiPF6, LiAsF6, LiSbF6, LiCF3SO3, LiBF4, lithium di(oxalate)borate, LiClO4, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2 and LiPF3(CF2CF3)3, more preferably the conductive salt is selected from LiPF6, LiN(SO2F)2 and LiBF4, and the most preferred conductive salt is LiPF6.

[0065] The conductive salt (ii) is generally present in a minimum concentration of at least 0.1 mol / l, based on the entire electrolyte composition, preferably in a concentration of 0.5 to 2 mol / l containing the ion-conductive salt.

[0066] The electrolyte composition contains at least one silylphosphonate having the structure of formula (I):

[0067]

[0068] in

[0069] T is selected from

[0070] p is an integer from 0 to 6 and one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl;

[0071] R 1 is independently selected at each occurrence from H, F, Cl, R 4 , OR 4 、OSi(R 5 )3、OSi(OR 4 )3 and OP(O)(OR 4 )R 5 ;

[0072] R 4 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to a Si atom or an O atom may be replaced by O;

[0073] R 3 and R 5 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the P atom may be replaced by O.

[0074] The silylphosphonate comprising the structure of formula (I) is also referred to as component (iii) of the electrolyte composition.

[0075] The term "C1-C 10 "Alkyl" refers to a straight-chain or branched saturated hydrocarbon group having 1 to 10 carbon atoms with one free valence bond, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, 2-ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, n-decyl, etc. Preferably C1-C6 alkyl, more preferably C1-C4 alkyl, even more preferably methyl, ethyl, n-propyl and isopropyl, most preferably methyl and ethyl.

[0076] The term "C3-C7 (hetero)cycloalkyl" as used herein refers to a saturated 3-7 membered hydrocarbon ring having one free valence bond, wherein one or more carbon atoms of the saturated ring may be replaced independently of one another by heteroatoms selected from N, S, O and P. Examples of C3-C7 cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl, preferably cyclohexyl. Examples of C3-C7 heterocycloalkyl are oxirane, tetrahydrofuranyl, pyrrolidinyl, piperidinyl and morpholinyl.

[0077] The term "C2-C 10 "Alkenyl" refers to an unsaturated straight-chain or branched hydrocarbon radical having 2 to 10 carbon atoms and having one free valence bond. Unsaturation means that the alkenyl contains at least one C-C double bond. 10 Alkenyl groups include, for example, vinyl, propenyl, 1-n-butenyl, 2-n-butenyl, isobutenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, 1-decenyl, etc. C2-C6 alkenyl is preferred, C2-C4 alkenyl is even more preferred, vinyl and propenyl are more preferred, and 1-propen-3-yl, also known as allyl, is most preferred.

[0078] The term "C2-C 10 "Alkynyl" refers to an unsaturated straight-chain or branched hydrocarbon radical having 2 to 10 carbon atoms with one free valence bond, wherein the hydrocarbon radical contains at least one C-C triple bond. C-Calkynyl includes, for example, ethynyl, propynyl, 1-n-butynyl, 2-n-butynyl, isobutynyl, 1-pentynyl, 1-hexynyl, 1-heptynyl, 1-octynyl, 1-nonynyl, 1-decynyl, etc. C-Calkynyl is preferred, C-Calkynyl is even more preferred, ethynyl and 1-propyn-3-yl (propargyl) are more preferred.

[0079] The term "C5-C7 (hetero)aryl" as used herein means a 5-7 membered aromatic hydrocarbon ring or condensed ring having one free valence bond, wherein one or more carbon atoms of the aromatic ring may be replaced independently of one another by heteroatoms selected from N, S, O and P. Examples of C5-C7 (hetero)aryl are pyrrolyl, furanyl, thienyl, pyridyl, pyranyl, thiopyranyl and phenyl. Phenyl is preferred.

[0080] The term "C6-C 13 "(Hetero)aralkyl" means an aromatic 5-7 membered hydrocarbon ring substituted by one or more C1-C6 alkyl groups, wherein one or more carbon atoms of the aromatic ring may be independently replaced by a heteroatom selected from N, S, O and P. 13 (Hetero)aralkyl contains 6-13 carbon atoms and heteroatoms in total and has one free valence bond. The free valence bond can be located in the aromatic ring or in the C1-C6 alkyl group, i.e., C6-C 13The (hetero)aralkyl group can be bonded via the (hetero)aromatic part of the group or via the alkyl part of the group. 13 Examples of (hetero)aralkyl groups are methylphenyl, 2-methylpyridyl, 1,2-dimethylphenyl, 1,3-dimethylphenyl, 1,4-dimethylphenyl, ethylphenyl, 2-propylphenyl, benzyl, 2-CH2-pyridyl and the like.

[0081] R 1 independently selected at each occurrence from H, F, Cl, R 4 , OR 4 、OSi(R 5 )3、OSi(OR 4 )3 and OP(O)(OR 4 )R 5 ,

[0082] R 4 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to Si atoms or O atoms may be replaced by O. Preferably, R 4 In each occurrence, independently selected from C1-C 10 Alkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups not directly bonded to Si atoms or O atoms may be replaced by O, more preferably R 4 is independently selected at each occurrence from C1-C4 alkyl, which may be substituted with one or more substituents selected from CN and F. For example, R 4 It can be selected from methyl, ethyl, n-propyl, isopropyl, phenyl, cyclohexyl, CF3, CF2CF3 or CH2CN.

[0083] R 5 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups not directly bonded to the P atom may be replaced by O, preferably R 5is independently selected at each occurrence from H, F and Cl-C 10 Alkyl, which may be substituted by one or more CN and F and in which one or more CH2 groups of the alkyl not directly bonded to the P atom may be replaced by O, more preferably R 5 is independently selected at each occurrence from H and C1-C 10 Alkyl, which may be substituted by one or more F and / or CN, even more preferably R 5 is independently selected at each occurrence from H and C1-C4 alkyl, which may be substituted with one or more F and / or CN. 5 It can be selected from H, F, methyl, ethyl, n-propyl, isopropyl, phenyl, cyclohexyl, CF3, CF2CF3 or CH2CN.

[0084] Preferably, R 1 is independently selected at each occurrence from H, F, Cl, Cl-C 10 Alkyl and OC1-C 10 Alkyl, wherein the alkyl group may be substituted by one or more substituents selected from CN and F and wherein one or more CH2 groups of the alkyl group not directly bonded to a Si atom or an O atom may be replaced by O, even more preferably R 1 independently selected from C1-C1 which may be substituted with one or more substituents selected from CN and F 10 Alkyl. Particularly preferred is R 1 R is independently selected from C1-C4 alkyl which may be substituted by one or more substituents selected from CN and F. 1 For example, each occurrence is independently selected from H, F, Cl, methyl, methoxy, ethyl, ethoxy, n-propyl, n-propoxy, isopropyl, isopropoxy, phenyl, phenoxy, CF3, OCF3, CF2CF3, OCF2CF3 and CH2CN, preferably selected from methyl, ethyl, isopropyl and n-propyl.

[0085] R 3 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups not directly bonded to the P atom may be replaced by O, preferably R 3 independently selected at each occurrence from H, F, Cl-C 10Alkyl, C3-C7 (hetero)cycloalkyl and C5-C7 (hetero)aryl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups not directly bonded to the P atom may be replaced by O, more preferably R 3 is independently selected at each occurrence from H, F and Cl-C 10 Alkyl, which may be substituted by one or more F and / or CN and in which one or more CH2 groups of the alkyl not directly bonded to the P atom may be replaced by O, even more preferably R 3 is independently selected at each occurrence from H and C1-C 10 Alkyl, which may be substituted by one or more F and / or CN and in which one or more CH2 groups of the alkyl not directly bonded to the P atom may be replaced by O. Most preferably R 3 is independently selected at each occurrence from H and C1-C4 alkyl, which may be substituted with one or more F and / or CN. 3 It can be selected from H, F, methyl, ethyl, n-propyl, isopropyl, cyclohexyl, phenyl, CF3, CF2CF3, CH2CH2OCH3, CH2CH2OCH3 and CH2CN. R is particularly preferred. 3 For H.

[0086] T is selected from p is an integer from 0 to 6 and may be 1, 2, 3, 4, 5 or 6. One or more CH2 groups of (CH2)p may be replaced by O, for example to give CH2-O-CH2 or CH2-O-CH2-O-CH2. In the case where more than one CH2 group is replaced by O, the CH2 groups replaced by O are not adjacent. One or more H of (CH2)p may be replaced by C1-C4 alkyl. Examples of (CH2)p in which one or more H is replaced by C1-C4 alkyl are C(CH3)H, C(CH3)2, C(CH3)HCH2, C(CH3)HC(CH3)H and C(CH3)HC(C2H4)H.

[0087] Examples of structures of formula (I) are the following structures (1.1) to (1.5):

[0088]

[0089] Preferably, the silylphosphonate containing the structure of formula (I) is selected from -P(O)R 3 -OC1-C6 alkyl phosphonate group, more preferably selected from -P(O)R 3 -OC1-C4 phosphonate group, particularly preferably selected from -P(O)R 3 -OCH3 and -P(O)R 3 -OCH2CH3 phosphonate end-capping.

[0090] According to one embodiment, the silylphosphonate comprises the structure of formula (II):

[0091]

[0092] in

[0093] Q 1 is a chemical bond or a monomer or oligomeric group containing one or more monomer units of formula (II.1), and Q 2 is a chemical bond or a monomer or oligomeric group containing one or more monomer units of formula (II.2):

[0094]

[0095] in

[0096] T * is independently Si or Si-(CH2) at each occurrence p -Si, wherein p is an integer from 0 to 6, i.e., p is selected from 0, 1, 2, 3, 4, 5 and 6, one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl, and in T * In the case of Si, q 1 is an integer between 0 and 2, q 2 is an integer from 0 to 2, and q 1 +q 2 =2, that is, q 1 and q 2 is selected from 0, 1 and 2, where q 1 +q 2 =2;

[0097] In T * Si-(CH2) p -Si case, q 1 is an integer from 0 to 4, q 2 is an integer from 0 to 4, and q 1 +q 2 =4, that is, q 1 and q 2 is selected from 0, 1, 2, 3 and 4, where q 1 +q 2 =4;

[0098] - * is a continuation of the silylphosphonate backbone through a branch; and

[0099] R 1 and R 3 As described above and as preferably defined.

[0100] Q 1 Examples are:

[0101]

[0102]

[0103] Q 2 Examples are:

[0104]

[0105] Q 1 and Q 2 The monomer units may be arranged in any manner, such as randomly or in blocks or in alternating order.

[0106] Preferably, Q 1 and / or Q 2 Each comprises at least one monomer unit of formula (II.1) or formula (II.2) without branching or crosslinking units, ie wherein T * is independently Si or Si-(CH2) at each occurrence p -Si and p is an integer from 0 to 6, and one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl, and wherein in T * In the case of Si, q 1 is zero and q 2 is 2, and at T * Si-(CH2) p -Si case, q 1 is zero and q 2 is 4.

[0107] According to another embodiment, the silylphosphonate has the formula (III)

[0108]

[0109] in

[0110] Q 1 , Q 2 , T and R 3 Defined as above.

[0111] R 6 and R 7 Independently selected from R 8 、Si(OR 8 )3 and Si(R 9 )3;

[0112] R 8In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl groups which may be substituted by one or more substituents selected from the group consisting of CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to an O atom or Si atom may be replaced by O; and

[0113] R 9 is independently selected at each occurrence from H, F, Cl, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the O atom may be replaced by O.

[0114] Preferred R 6 and R 7 Independently selected from C1-C 10 Alkyl, Si(OC1-C 10 Alkyl)3 and Si(R 9 )3, where R 9 is independently selected at each occurrence from H, F, Cl and Cl-C 10 Alkyl, more preferably R 9 R is selected from H, F, Cl and C1-C4 alkyl. 6 and R 7 It can be selected, for example, from methyl, ethyl, n-propyl, isopropyl, Si(CH3)3, Si(OCH3)3, Si(CH3)2Cl and Si(CH3)Cl2. Even more preferably, R 6 and R 7 Independently selected from C1-C4 alkyl, that is, silylphosphonate is terminated by alkoxy groups such as methoxy, ethoxy, n-propoxy and n-butoxy, and methoxy and ethoxy terminated silylphosphonate are particularly preferred.

[0115] The silylphosphonate may in particular have the formula (IV)

[0116]

[0117] in

[0118] R 1 , R 3 , R 6 , R7 , T, T * ,q 1 and q 2 As defined above and preferably, and

[0119] r 1 and r 2 are independently integers from 0 to 300.

[0120] According to one embodiment of the present invention, the silylphosphonic acid ester containing the structure of formula (I) is a mixture of different silylphosphonic acid esters with different molecular weights, in particular a mixture of a monomeric silylphosphonic acid ester containing the structure of formula (I) without repeating monomer units and at least one oligomeric or polymeric silylphosphonic acid ester containing the structure of formula (I) and one or more repeating monomer units, for example, wherein r 1 and r 2 are all zero and at least one compound of formula (IV) wherein r 1 +r 2 >1 mixture of oligomeric or polymeric silylphosphonates of formula (IV).

[0121] The preparation of similar silylphosphonates containing the structure of formula (I) is known to those skilled in the art, see, for example, K. Kellner, L. Rodewald, Monatshefte für Chemie, Volume 121 (1990), pages 1031-1038. The oligomeric silylphosphonates used according to the invention can be prepared similarly. Depending on the starting materials, linear compounds or compounds with branching points or crosslinking functional groups can be obtained. For example, the reaction of (CH3)2SiCl2 with dimethyl phosphite will give linear silylphosphonates. In the case where part of the (CH3)2SiCl2 is replaced by (CH3)SiCl3 or SiCl4, monomer units are introduced into the silylphosphonate, which acts as a branching or crosslinking point. In addition, (CH3)2SiCl2 can be replaced by dichlorodisilanes interrupted by alkylene groups, such as Cl(CH3)2Si(CH2)2Si(CH3)2Cl. Depending on the starting compounds, the molar ratios and the reaction conditions, mixtures of different silylphosphonates and generally monomeric silylphosphonates with one or more oligomeric and polymeric silylphosphonates of different molecular weight are obtained.

[0122] Another aspect of the invention is the use of a silylphosphonate containing the structure of formula (I) in an electrolyte composition for use in an electrochemical cell, such as in a lithium ion capacitor, a double layer capacitor and a lithium battery, especially a secondary lithium battery as described below. The silylphosphonate containing the structure of formula (I) is particularly suitable as a cathode active material capable of interacting with the cathode at the cathode-electrolyte interface, thereby reducing undesirable reactions of the cathode active material with the electrolyte composition, for example by forming a film on the cathode or by inhibiting the formation of electrolyte decomposition products (such as HF) that are harmful to the operation of the battery, thereby inhibiting direct contact of the components of the electrolyte composition with the cathode active material. Direct contact of the electrolyte composition with the cathode generally results in a decomposition reaction.

[0123] Silylphosphonates containing the structure of formula (I) can also be used as additives to reduce gas generation in electrolyte compositions used in electrochemical cells, such as lithium ion capacitors, double layer capacitors and lithium batteries, especially secondary lithium batteries as described below. The undesirable generation of gas in electrochemical cells is a safety issue because the increase in internal pressure can lead to cell leakage and loss of electrolyte composition, which increases the possibility of fire and the emission of unhealthy compounds.

[0124] The silylphosphonates containing the structure of formula (I) are generally used in the electrolyte composition at the electrolyte composition concentrations given below by adding the desired amount of the compound of formula (I) to the electrolyte composition. Depending on the molecular weight and the presence of branching / crosslinking units, the silylphosphonates can be dissolved or swelled in the non-aqueous solvent (ii).

[0125] The electrolyte composition may contain one silylphosphonate having the structure of formula (I), and it may contain more than one, for example two, three or more silylphosphonates having the structure of formula (I).

[0126] The electrolyte composition generally contains at least 0.01% by weight, preferably at least 0.02% by weight, and more preferably at least 0.1% by weight of at least one silylphosphonate containing the structure of formula (I) based on the total weight of the electrolyte composition. The maximum value of the total concentration of the silylphosphonate containing the structure of formula (I) in the electrolyte composition is generally 10% by weight, preferably 5% by weight, and more preferably the upper limit of the total concentration of the silylphosphonate containing the structure of formula (I) is 3% by weight based on the total weight of the electrolyte composition. The electrolyte composition generally contains 0.01-10% by weight, preferably 0.02-10% by weight, more preferably 0.1-5% by weight, and most preferably 0.1-3% by weight of at least one silylphosphonate containing the structure of formula (I) based on the total weight of the electrolyte composition.

[0127] In addition, the electrolyte composition may contain at least one other additive different from the silylphosphonate containing the structure of formula (I). The at least one other additive different from the silylphosphonate containing the structure of formula (I) may be selected from polymers, film-forming additives, flame retardants, overcharge additives, wetting agents, HF and / or H2O scavengers, stabilizers for LiPF6 salts, ionic solvation enhancers, corrosion inhibitors and gelling agents.

[0128] The minimum concentration of the at least one other additive is usually 0.005 wt %, preferably 0.01 wt %, more preferably 0.1 wt %, based on the total weight of the electrolyte composition. The maximum concentration of the at least one other additive is usually 25 wt %.

[0129] A class of other additives is a polymer. The polymer can be selected from polyvinylidene fluoride, polyethylene-hexafluoropropylene copolymer (polyvinylidene-hexafluoropropylene copolymer), polyethylene-hexafluoropropylene-chlorotrifluoroethylene copolymer (polyvinylidene-hexafluoropropylene-chlorotrifluoroethylene copolymer), Nafion, polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, polypropylene, polystyrene, polybutadiene, polyethylene glycol, polyvinyl pyrrolidone, polyaniline, polypyrrole and / or polythiophene. Polymers can be added to the formulation of the present invention to convert the liquid formulation into a quasi-solid or solid electrolyte and thus improve solvent retention, especially during aging. At this point they are used as gelling agents.

[0130] Examples of flame retardants are organophosphorus compounds such as cyclophosphanitriles, phosphoramides, alkyl and / or aryl trisubstituted phosphates, alkyl and / or aryl di- or trisubstituted phosphites, alkyl and / or aryl disubstituted phosphonates, alkyl and / or aryl trisubstituted phosphines and their fluorinated derivatives.

[0131] Examples of HF and / or H2O scavengers are optionally halogenated cyclic and acyclic silylamines.

[0132] Examples of the overcharge protection additive are cyclohexylbenzene, o-terphenyl, p-terphenyl, biphenyl, and the like, with cyclohexylbenzene and biphenyl being preferred.

[0133] Another class of additives is film-forming additives, also known as SEI-forming additives. The SEI-forming additive according to the present invention is a compound that decomposes on an electrode and forms a passivation layer on the electrode that prevents degradation of the electrolyte and / or the electrode. In this way, the life of the battery pack is significantly extended. Preferably, the SEI-forming additive forms a passivation layer on the anode. The anode should be understood in the context of the present invention as the negative electrode of the battery pack. Preferably, the anode, such as a lithium intercalated graphite anode, has a reduction potential of 1V or less for lithium. In order to determine whether a compound is suitable as an anode film-forming additive, an electrochemical cell comprising a graphite electrode and a metal counter electrode and an electrolyte containing a small amount, typically 0.1-10% by weight of the electrolyte composition, preferably 0.2-5% by weight of the compound can be prepared. When a voltage is applied between the anode and the metallic lithium, the differential capacitance of the electrochemical cell is recorded between 0.5-2V. If a significant differential capacitance is observed during the first cycle, for example -150mAh / V at 1V, but no or substantially no capacitance is observed during any subsequent cycle within the voltage range, the compound can be considered to be an SEI-forming additive.

[0134] According to the present invention, the electrolyte composition preferably contains at least one SEI-forming additive. Additives that form SEI are known to those skilled in the art. More preferably, the electrolyte composition contains at least one SEI-forming additive selected from the following: vinylene carbonate and its derivatives such as vinylene carbonate and methyl vinylene carbonate; fluoroethylene carbonate and its derivatives such as monofluoroethylene carbonate, cis- and trans-difluorocarbonate; organic sultones such as propylene sultone, propane sultone and its derivatives; ethylene sulfite and its derivatives; compounds containing oxalate such as lithium oxalate, oxalate borates including dimethyl oxalate, lithium bisoxalate borate, lithium difluoro oxalate borate and ammonium bisoxalate borate, and oxalate phosphates including lithium tetrafluoro oxalate phosphate; and sulfur-containing additives described in detail in WO 2013 / 026854 A1, especially the sulfur-containing additives shown on page 12, line 22 to page 15, line 10.

[0135] The added compounds can have more than one effect in the electrolyte composition and electrochemical cells containing the electrolyte composition. For example, lithium oxalatoborate can be added as an additive to enhance SEI formation, but can also function as a conductive salt.

[0136] In one embodiment of the invention, the water content of the electrolyte composition is preferably less than 100 ppm, more preferably less than 50 ppm, most preferably less than 30 ppm based on the weight of the corresponding formulation of the invention. The water content can be determined by titration according to Karl Fischer, for example as described in detail in DIN 51777 or ISO 760: 1978. The minimum water content of the electrolyte composition can be selected to be 3 ppm, preferably 5 ppm.

[0137] In one embodiment of the present invention, the HF content of the electrolyte composition is preferably less than 100 ppm, more preferably less than 50 ppm, most preferably less than 30 ppm, based on the weight of the corresponding inventive formulation. The HF content can be determined by titration.

[0138] The electrolyte composition is preferably liquid under working conditions; more preferably it is liquid at 1 bar and 25° C., even more preferably the electrolyte composition is liquid at 1 bar and -15° C., the electrolyte composition is especially liquid at 1 bar and -30° C., even more preferably the electrolyte composition is liquid at 1 bar and -50° C. Such liquid electrolyte compositions are particularly suitable for outdoor applications, for example in automotive batteries.

[0139] The electrolyte composition (A) can be prepared by methods known to those skilled in the art of electrolyte production, generally by dissolving the lithium conductive salt (i) in a corresponding solvent or solvent mixture (ii) and adding the at least one silylphosphonic acid ester containing the structure of formula (I) and optionally other additives (iv) as described above.

[0140] The electrochemical cell comprising the electrolyte composition (A) may be a lithium battery, a double layer capacitor or a lithium ion capacitor. The general construction of such electrochemical devices is known and familiar to those skilled in the art for batteries.

[0141] Preferably, the electrochemical cell of the present invention is a lithium battery. As used herein, the term "lithium battery" refers to an electrochemical cell in which the anode sometimes contains metallic lithium or lithium ions during the charge / discharge process of the cell. The anode may contain metallic lithium or a metallic lithium alloy, a material that occludes and releases lithium ions, or other lithium-containing compounds. The lithium battery is preferably a secondary lithium battery, i.e., a rechargeable lithium battery.

[0142] In a particularly preferred embodiment, the electrochemical cell is a lithium ion battery, i.e. a secondary lithium ion electrochemical cell, comprising a cathode (A) comprising a cathode active material that can reversibly store and release lithium ions and an anode (B) comprising an anode active material that can reversibly store and release lithium ions.

[0143] The anode (A) contains an anode active material that can reversibly occlude and release lithium ions or can form an alloy with lithium. In particular, a carbonaceous material that can reversibly occlude and release lithium ions can be used as the anode active material. Suitable carbonaceous materials are crystalline carbons such as graphite materials, more specifically natural graphite, graphitized coke, graphitized MCMB, and graphitized MPCF; amorphous carbons such as coke, mesocarbon microspheres (MCMB) fired below 1500 °C, and mesophase pitch-based carbon fibers (MPCF); hard carbons; and carbonic anode active materials (thermally decomposed carbon, coke, graphite) such as carbon composites, burned organic polymers, and carbon fibers. The preferred carbonaceous material is graphite.

[0144] Other examples of anode active materials are metallic lithium and metallic lithium alloys, i.e., materials containing elements that can form an alloy with lithium. Non-limiting examples of materials containing elements that can form an alloy with lithium include metals, metalloids, or alloys thereof. It should be understood that the term "alloy" as used herein refers to both alloys of two or more metals and alloys of one or more metals together with one or more metalloids. If the alloy as a whole has metallic properties, the alloy may contain non-metallic elements. In the texture of the alloy, solid solutions, eutectics (eutectic mixtures), intermetallic compounds, or two or more of these coexist. Examples of such metal or metalloid elements include, but are not limited to, titanium (Ti), tin (Sn), lead (Pb), aluminum, indium (In), zinc (Zn), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr), yttrium (Y), and silicon (Si). Metals and metalloid elements in the 4th or 14th group of the long form periodic table are preferred, with titanium, silicon, and tin being particularly preferred, especially silicon. Examples of tin alloys include those having one or more elements selected from silicon, magnesium (Mg), nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti), germanium, bismuth, antimony, and chromium (Cr) as the second constituent element other than tin. Examples of silicon alloys include those having one or more elements selected from tin, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium as the second constituent element other than silicon.

[0145] Other possible anode active materials are silicon-containing materials. Silicon-containing materials include silicon itself, such as amorphous and crystalline silicon, silicon-containing compounds, such as SiO where 0 < x < 1.5 xand Si alloys, and compositions containing silicon and / or silicon-containing compounds, such as silicon / graphite composites and carbon-coated silicon-containing materials. Silicon itself can be used in different forms, for example in the form of nanowires, nanotubes, nanoparticles, thin films, nanoporous silicon or silicon nanotubes. The silicon can be deposited on a current collector. The current collector can be selected from coated metal wires, coated metal grids, coated metal meshes, coated metal sheets, coated metal foils or coated metal plates. Preferably, the current collector is a coated metal foil, especially a coated copper foil. The silicon thin film can be deposited on the metal foil by any technique known to those skilled in the art, for example by sputtering technology. A method for preparing a silicon thin film electrode is described in R. Elazari et al.; Electrochem. Comm. 2012, 14, 21-24.

[0146] Other possible anode active materials are lithium ion intercalation oxides of Ti.

[0147] Preferably, the anode active material comprises a carbonaceous material that can reversibly contain and release lithium ions, and particularly preferably, the carbonaceous material that can reversibly contain and release lithium ions is selected from crystalline carbon, hard carbon and amorphous carbon, and particularly preferably graphite. It is also preferred that the anode active material comprises a silicon-containing material. It is further preferred that the anode active material comprises a lithium ion intercalation oxide of Ti.

[0148] The electrochemical cell of the present invention comprises a cathode (B) comprising at least one cathode active material. The at least one cathode active material comprises a material capable of occluding and releasing lithium ions and is selected from a mixed lithium transition metal oxide containing Mn and at least one second transition metal, a lithium intercalation mixed oxide containing Ni, Al and at least one second transition metal, LiNiPO4, LiNiPO4 and LiCoPO4.

[0149] An example of a mixed lithium transition metal oxide containing Mn and at least one second transition metal is a lithium transition metal oxide having a layered structure of formula (II):

[0150] Li 1+e (Ni a Co b Mn c M d ) 1-e O2 (II)

[0151] in

[0152] a is 0.05-0.9, preferably 0.1-0.8,

[0153] b is 0-0.35,

[0154] c is 0.1-0.9, preferably 0.2-0.8,

[0155] d is 0-0.2,

[0156] e is 0-0.3, preferably >0-0.3, more preferably 0.05-0.3,

[0157] a+b+c+d=1, and

[0158] M is one or more metals selected from the group consisting of Na, K, Al, Mg, Ca, Cr, V, Mo, Ti, Fe, W, Nb, Zr and Zn.

[0159] The cobalt-containing compound of formula (II) is also referred to as NCM.

[0160] Lithium transition metal oxides of the formula (II) having a layered structure in which e is greater than 0 are also referred to as perlithiated.

[0161] Preferably, the lithium transition metal oxide with a layered structure of formula (II) is a compound that forms a solid solution, wherein the LiM'O2 phase - wherein M' is Ni and, optionally, one or more transition metals selected from Co and Mn - and the Li2MnO3 phase are mixed and wherein one or more metals M as defined above may be present. The one or more metals M are also referred to as "dopants" or "doping metals" because they are usually present in small amounts, for example, a maximum of 10 mol% M or a maximum of 5 mol% M or a maximum of 1 mol% based on the total amount of metals other than lithium present in the transition metal oxide. In the case of the presence of one or more metals M, they are usually present in an amount of at least 0.01 mol% or at least 0.1 mol% based on the total amount of metals other than lithium present in the transition metal oxide. These compounds are also represented by formula (IIa):

[0162] z LiM'O2·(1-z)Li2MnO3 (IIa)

[0163] Wherein M' is Ni and at least one metal selected from Mn and Co;

[0164] z is 0.1-0.8,

[0165] And one or more metals selected from Na, K, Al, Mg, Ca, Cr, V, Mo, Ti, Fe, W, Nb, Zr and Zn may be present therein.

[0166] Electrochemically, Ni and, if present, Co atoms in the LiM'O2 phase play a role in the + / Li participates in reversible oxidation and reduction reactions at voltages below 4.5 V, leading to Li ion deintercalation and intercalation, respectively, while the Li2MnO3 phase only reacts with Li + / Li participates in oxidation and reduction reactions at voltages equal to or higher than 4.5 V, assuming that the Mn in the Li2MnO3 phase is in its +4 oxidation state. Therefore, electrons are not removed from Mn atoms in this phase but from the 2p orbitals of oxygen ions, resulting in oxygen being removed from the lattice in the form of O2 gas in at least the first charging cycle.

[0167] These compounds are also called HE-NCMs due to their higher energy density compared to conventional NCMs. Both HE-NCMs and NCMs have specific Li / Li + The operating voltage is about 3.0-3.8 V, but a high cut-off voltage must be used for both activation and cycling of HE-NCM to actually complete full charging and benefit from its higher energy density. + The upper cut-off voltage for activating the HE-NCM is at least 4.5 V, preferably at least 4.6 V, more preferably at least 4.7 V, and even more preferably at least 4.8 V. The term "charge during charging of the electrochemical cell to Li / Li + The upper cut-off voltage is the voltage at which the cathode of the electrochemical cell reacts with Li / Li + The voltage of the reference anode, which constitutes the upper voltage limit when charging the electrochemical cell. An example of HE-NCM is 0.33Li2MnO3·0.67Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.42Li2MnO3·0.58Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.50Li2MnO3·0.50Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.40Li2MnO3·0.60Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 and 0.42Li2MnO3·0.58Li(Ni 0.6 Mn 0.4 )O2.

[0168] An example of a manganese-containing transition metal oxide having a layered structure of formula (II) in which d is 0 is LiNi 0.33 Mn 0.67 O2、LiNi 0.25 Mn 0.75 O2、LiNi 0.35 Co 0.15 Mn 0.5 O2、LiNi 0.21 Co 0.08 Mn0.71 O2、LiNi 0.22 Co 0.12 Mn 0.66 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.5 Co 0.2 Mn 0.3 O2. Preferably, the transition metal oxide of the general formula (II) in which d is 0 does not contain other cations or anions in significant amounts.

[0169] An example of a manganese-containing transition metal oxide having a layered structure of formula (II) in which d is greater than 0 is 0.33Li2MnO3·0.67Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.42Li2MnO3·0.58Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.50Li2MnO3·0.50Li(Ni 0.4 Co 0.2 Mn 0.4 )O2、0.40Li2MnO3·0.60Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 and 0.42Li2MnO3·0.58Li(Ni 0.6 Mn 0.4 )O2, wherein one or more metals M selected from the group consisting of Na, K, Al, Mg, Ca, Cr, V, Mo, Ti, Fe, W, Nb, Zr and Zn may be present. The one or more doping metals are preferably present in an amount of up to 1 mol % based on the total amount of metals other than lithium present in the transition metal oxide.

[0170] Other preferred compounds of formula (II) are Ni-rich compounds, wherein the Ni content is at least 50 mol %, based on the total amount of transition metals present. This includes compounds of formula (IIb):

[0171] Li 1+e (Ni a Co b Mn c M d ) 1-e O2 (IIb)

[0172] in

[0173] a is 0.5-0.9, preferably 0.5-0.8,

[0174] b is 0-0.35,

[0175] c is 0.1-0.5, preferably 0.2-0.5,

[0176] d is 0-0.2,

[0177] e is 0-0.3,

[0178] where a+b+c+d=1, and

[0179] M is one or more metals selected from the group consisting of Na, K, Al, Mg, Ca, Cr, V, Mo, Ti, Fe, W, Nb, Zr and Zn.

[0180] An example of a Ni-rich compound of formula (I) is Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2(NCM811), Li[Ni 0.6 Co 0.2 Mn 0.2 ]O2(NCM 622) and Li[Ni 0.5 Co 0.2 Mn 0.3 ]O2(NCM 523).

[0181] Other examples of mixed lithium transition metal oxides containing Mn and at least one second transition metal are manganese-containing spinels of formula (III):

[0182] Li 1+t M 2-t O 4-s (III)

[0183] in

[0184] s is 0-0.4,

[0185] t is 0-0.4, and

[0186] M is Mn and at least one other metal selected from Co and Ni, preferably M is Mn and Ni and optionally Co, ie a portion of M is Mn and another portion is Ni and optionally another portion of M is selected from Co.

[0187] The cathode active material can also be selected from lithium intercalation mixed oxides containing Ni, Al and at least one second transition metal, such as lithium intercalation mixed oxides of Ni, Co and Al. An example of a mixed oxide of Ni, Co and Al is a compound of formula (IV):

[0188] Li[Ni h Co i Al j ]O2 (IV)

[0189] in

[0190] h is 0.7-0.9, preferably 0.8-0.87, more preferably 0.8-0.85;

[0191] i is 0.15-0.20; and

[0192] j is 0.02-10, preferably 0.02-1, more preferably 0.02-0.1, most preferably 0.02-0.03.

[0193] The cathode active material may also be selected from LiMnPO 4 , LiNiPO 4 and LiCoPO 4 . These phosphates generally exhibit an olivine structure and generally must be charged using an upper cutoff voltage of at least 4.5 V.

[0194] The cathode (B) may contain other components such as binders and conductive materials such as conductive carbon. For example, the cathode (B) may include carbon in a conductive polymorph, such as a mixture of at least two of graphite, carbon black, carbon nanotubes, graphene or the above substances. Examples of binders for the cathode (B) are organic polymers such as polyethylene, polyacrylonitrile, polybutadiene, polypropylene, polystyrene, polyacrylates, polyvinyl alcohol, polyisoprene and at least two copolymers of comonomers selected from ethylene, propylene, styrene, (meth) acrylonitrile and 1,3-butadiene, especially styrene-butadiene copolymers, and halogenated (co)polymers such as polyvinylidene chloride, polyvinyl chloride, polyvinyl fluoride, polyvinylidene fluoride (PVdF), polytetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene copolymers, tetrafluoroethylene and vinylidene fluoride copolymers and polyacrylonitrile.

[0195] Anode (A) and cathode (B) can be prepared by dispersing an electrode active material, a binder, optionally a conductive material and a thickener in a solvent to prepare an electrode slurry composition and applying the slurry composition to a current collector. The current collector can be a metal wire, a metal grid, a metal mesh, a metal sheet, a metal foil or a metal plate. Preferably, the current collector is a metal foil, such as a copper foil or an aluminum foil.

[0196] The electrochemical cell of the invention may contain other components which are conventional per se, such as separators, housings, cable connections, etc. The housing may have any shape, such as a cubic or cylindrical shape, a prism shape, or the housing used is a metal-plastic composite film processed into a bag. Suitable separators are, for example, glass fiber separators and polymer-based separators, such as polyolefin or Nafion separators.

[0197] Several electrochemical cells of the present invention can be combined with each other, for example connected in series or in parallel. Preferably connected in series. The present invention further provides the use of the above-mentioned electrochemical cell of the present invention in a device, especially a mobile device. Examples of mobile devices are vehicles, such as cars, bicycles, airplanes, or water vehicles such as ships or boats. Other examples of mobile devices are portable ones, such as computers, especially laptop computers, telephones or power tools, such as power tools in the construction field, especially drills, battery-powered screwdrivers or battery-powered staplers. However, the electrochemical cell of the present invention can also be used in fixed energy storage stations.

[0198] The present invention is further illustrated by the following examples, which however do not limit the present invention.

[0199] Experimental part:

[0200] I. Additives:

[0201] I.1 Overview of electrolyte additives used:

[0202]

[0203]

[0204] Ph: phenyl

[0205] The units in square brackets represent repeating monomer units. The oligomers are usually terminated with -OP(O)H-OCH3 or -OP(O)H-OCH2CH3, except that these oligomers contain Si(CH3)3 end groups.

[0206] I.2 Preparation of additives

[0207] Comparative additive R1 is commercially available. Comparative additive R2 was prepared according to R. Rabinowitz, J. Org. Chem., Vol. 28 (1963), pp. 2975-2978. Additive mixtures M1 to M12 containing molecular entities A1 to A19 were synthesized according to K. Kellner, L. Rodewald, Monatshefte für Chemie, Vol. 121 (1990), pp. 1031-1038.

[0208] All compounds were used directly after preparation. 1 H NMR spectroscopy and 31P NMR spectroscopy. Samples were prepared and measured under inert atmosphere using CDCl3 (7.26 ppm) as reference; when analyzing electrolytes, screw-cap NMR tubes were used, which were equipped with an inner tube filled with C6D6 (7.16 ppm) as reference. Spectra were recorded on a Bruker Avance III equipped with a CryoProbe Prodigy probe or 1 H:500.36MHz, 31 P: Varian NMR system 400 operated at 202.56 MHz. 31 P NMR data were collected with decoupling from protons {1H}. 31 The relaxation time D1 of the P NMR measurement was increased to 60 seconds to determine the amount of each substance P. The spectra were analyzed using MNova software.

[0209] To measure the viscosity, an Anton Paar Physica MCR 51 was used. The measurements were performed at 20°C with a speed of 1-1000 s. 1 The shear stress curves were performed and the average values ​​were calculated to obtain the given values.

[0210] Table 1 shows an overview of all additive mixtures prepared.

[0211] Experiment 1 - Mixture M1:

[0212] Following the above procedure, Me2SiCl2 (1.0 eq, 800 mmol, 104.8 g) was added to dimethyl phosphite (1.0 eq, 800 mmol, 88.0 g) at room temperature (RT) and stirred at 90°C for 1 h until the formation of volatile methyl chloride ceased. The flask with the formation of a colorless residue was equipped with a distillation bridge and heated (1 h, 100°C, 0.2 mbar) to give silyl-H-phosphonate M1 (105 g, 95% yield; chloride content 55 ppm) as a colorless oil.

[0213] M1 was obtained as a mixture of A1, dimer A2 and oligomer A3 with repeating units [PHO(OSiMe2O)] and CH3OP(O)H-end groups. The ratio of A1:A2:A3 was calculated by integrating 31 All signals in the range of -14 to -17.5 ppm (for A3), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A3 was found to be 1:27:72.

[0214] Viscosity: 170mPas

[0215] Mn(M1)=957g / mol 31 P NMR is measured as follows:

[0216] In theory, according to the structure Oligomer A3 can be divided into different units: two P-containing terminal groups [2x CH3OP(O)H-, totaling 158.03 g / mol], n repeating units containing Si and P [nx(CH3)2SiO2P(O)H- units, 138.14 g / mol each] and one additional (CH3)2SiO2- unit (90.15 g / mol).

[0217] To calculate the number average molecular weight, 31 The signal of the terminal group in the P-NMR spectrum (quantitatively measured with a relaxation time D1 = 60 s) was set to 2. As a result, the signal of the repeating unit gave the number of repeating units n. The number average molecular weight was calculated by adding the molecular weight of each terminal group, the molecular weight of the nx repeating unit and the molecular weight of the additional CH3)2SiO2- unit.

[0218] The reaction yield was calculated based on the difference between the amount of the starting material, the amount of the alkyl chloride released and the weight of the oligomer mixture obtained.

[0219] Experiment 2 - Mixture M2:

[0220] According to the conditions described in Experiment 1, Me2SiCl2 (0.9 eq, 765 mmol, 98.7 g), MeSiCl3 (0.1 eq, 85 mmol, 12.7 g) and dimethyl phosphite (1.0 eq, 850 mmol, 93.5 g) were converted to give M2 (95.0 g, 87% yield). The ratio of A1:A2:A4 was calculated by integration. 31 All signals in the range of -14 to -17.5 ppm (for A4), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A4 was found to be 2:35:63.

[0221] Viscosity: 180mPas

[0222] Experiment 3 - Mixture M3:

[0223] Me2SiCl2 (0.9 eq, 72 mmol, 9.47 g), SiCl4 (0.1 eq, 8 mmol, 1.4 g) and dimethyl phosphite (1.0 eq, 80 mmol, 8.8 g) were converted to give M3 according to the conditions described in Experiment 1. The ratio of A1:A2:A5 was determined by integration. 31All signals in the range of -14 to -17.5 ppm (for A5), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A5 was found to be 1:20:79.

[0224] Experiment 4 - Mixture M4:

[0225] According to the conditions described in Experiment 1, Me2SiCl2 (0.9 eq, 99 mmol, 12.9 g), Me3SiCl (0.1 eq, 11 mmol, 1.21 g) and dimethyl phosphite (0.73 eq, 80 mmol, 8.80 g) were converted to give M4 (8.80 g, 80% yield). The ratio of A1:A2:A6 was calculated by integration. 31 All signals in the range of -14 to -17.5 ppm (for A6), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A6 was found to be 1:34:65.

[0226] Experiment 5 - Mixture M5:

[0227] According to the conditions described in Experiment 1, Me2SiCl2 (1.0 eq, 850 mmol, 109.7 g) and dimethyl phosphite (1.0 eq, 850 mmol, 93.5 g) were reacted for a long time (4 h) at -10°C using a vertical powerful condenser with a cooling medium to obtain M5 (116.0 g, 98% yield) after distillation of all volatiles. The ratio of A1:A2:A3 was calculated by integration 31 All signals in the range of -14 to -17.5 ppm (for A3), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A3 was found to be 1:11:88.

[0228] Mn = 2021 g / mol As described for Experiment 1 by 31 P NMR determination.

[0229] Viscosity: 750mPas

[0230] Experiment 6 - Mixture M6:

[0231] According to the conditions described in Experiment 5, Me2SiCl2 (1.0 eq, 83 mmol, 107.5 g) and dimethyl phosphite (0.90 eq, 75 mmol, 82.5 g) were converted to give M6 (103.0 g, 99% yield). The ratio of A1:A2:A3 was calculated by integration.31 All signals in the range of -14 to -17.5 ppm (for A3), -2.5 ppm (for A2) and 10.4 ppm (for A1) in the PNMR spectrum were evaluated. For the above conditions, the ratio A1:A2:A3 was found to be 0:3:97.

[0232] Experiment 7 - Mixture M7:

[0233] According to the conditions described in Experiment 1, Me2SiCl2 (1.0 eq, 70 mmol, 9.12 g) and dimethyl methylphosphonate (1.0 eq, 70 mmol, 8.95 g) were converted to give M7 (9.80 g, 92% yield). The ratio of A7:A8:A9 was calculated by integration. 31 All signals in the range of 8-12 ppm (for A9), 21-23 ppm (for A8) and 33 ppm (for A7) in the PNMR spectrum were evaluated. For the above conditions, the ratio A7:A8:A9=1:30:69 was determined.

[0234] Experiment 8 - Mixture M8:

[0235] Me2SiCl2 (1.0 eq, 50 mmol, 6.45 g) and diethyl phosphite (1.0 eq, 50 mmol, 7.12 g) were converted to give M8 (3.80 g, 53% yield) according to the conditions described in Experiment 1. The ratio of A10:A11:A12 was calculated by integration 31 All signals in the range of -14 to -17.5 ppm (for A12), -4.2 ppm (for A11) and 7.2 ppm (for A10) in the P NMR spectrum were evaluated. For the above conditions, the ratio A10:A11:A12=1:81:18 was determined.

[0236] Experiment 10 - Mixture M10:

[0237] According to the conditions described in Experiment 1, Me2SiCl2 (1.0 eq, 70 mmol, 9.17 g) and dimethylphenylphosphonate (1.0 eq, 70 mmol, 13.30 g) were converted to give M10neu (13.6 g, 88% yield). The ratio of A13neu:A14neu:A15neu was calculated by integration. 31 All signals in the range of -0.2 to 2.5 ppm (for A15new), 10.4 ppm (for A14new) and 21.5 ppm (for A13new) in the P NMR spectrum were evaluated. For the above conditions, the ratio A13neu:A14neu:A15neu=1:55:44 was determined.

[0238] Viscosity: 1519mPas

[0239] Mn = 753 g / mol As described for Experiment 1 by 31 P NMR determination, except for the calculated terminal groups according to the structure [2x CH3OP(O)H-, totaling 310.24 g / mol], n repeating units containing Si and P [nx(CH3)2SiO2P(O)H- units, 214.25 g / mol each] and one additional (CH3)2SiO2- unit (90.15 g / mol).

[0240] Experiment 11 - Mixture M11:

[0241] According to the conditions described in Experiment 1, Et2SiCl2 (1.0 eq, 70 mmol, 7.86 g) and dimethyl phosphite (1.0 eq, 70 mmol, 11.34 g) were converted to give M11 (15.3 g, 98% yield). The ratio of A17:A16:A12 was calculated by integration. 31 All signals in the range of -14 to -17.5 ppm (for A17), -4.2 ppm (for A16) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A16:A17=2:90:8 was determined.

[0242] Experiment 12 - Mixture M12:

[0243] According to the conditions described in Experiment 1, ClMe2SiOSiMe2Cl (1.0 eq, 80 mmol, 6.45 g) and dimethyl phosphite (1.0 eq, 80 mmol, 9.00 g) were converted to give M12 (15.40 g, 87% yield). The ratio of A1:A18:A19 was calculated by integration. 31 All signals in the range of -15 to -17.5 ppm (for A12), -2.7 ppm (for A11) and 10.4 ppm (for A1) in the P NMR spectrum were evaluated. For the above conditions, the ratio A1:A18:A19=1:9:80 was determined.

[0244] Experiments 9 to 12 - Mixtures M9 to M12:

[0245] Mixtures M9 to M12 were prepared and evaluated as described in Experiment 1 with the educts, educt ratios and reaction conditions listed in Table 1. Table 1 also shows the composition of the resulting mixtures.

[0246] Table 1. Silylphosphonate mixtures prepared

[0247]

[0248] Me:CH3

[0249] Et:CH2CH3

[0250] II. Electrolyte Composition

[0251] Electrolyte compositions were prepared by dissolving 1.0 M LiPF6 in different mixtures of ethyl carbonate (EC, BASF), diethyl carbonate (DEC, BASF), monofluoroethylene carbonate (FEC, BASF), 1H,1H,5H-perfluoropentyl-1,1,2,2-tetrafluoroethyl ether (CF2H(CF2)3CH2OCF2CF2H, FPEE, Foosung Co., Ltd). Comparative additives R1 and R2 and the additive mixtures M1, M2 and M7 of the present invention were added to these compositions as shown in Table 2. R2, M1, M2 and M7 were used without further purification. "Volume %" refers to the volume of the solvent in the electrolyte composition. "Weight %" refers to the total weight of the electrolyte composition. All solvents are anhydrous (water content <3ppm). All electrolyte compositions were prepared and stored in an Ar-filled glove box with an oxygen and water content of less than 1.0ppm. Table 2 summarizes the electrolyte compositions used.

[0252] Table 2. Electrolyte composition

[0253]

[0254] III. Electrochemical Cells

[0255] III.1) HE-NCM / graphite 2032 coin full battery

[0256] The positive electrode for electrochemical cycling tests was prepared by coating a slurry containing 92.5 wt% cathode active material suspended in N-ethyl-2-pyrrolidone (NEP), 2 wt% graphite, 2 wt% Super C65 carbon black, and 3.5 wt% polyvinylidene fluoride (PVDF) binder on aluminum foil. The cathode active material was HE-NCM 0.42Li2MnO3·0.56Li(Ni 0.4 Mn 0.4 Co 0.2 )O2, HE-NCM, BASF). A commercially available graphite coated tape from Elexcel Corporation Ltd. was used as the negative electrode. 2032 coin cells were manufactured using the positive and negative composite electrodes, a polypropylene separator (Celgard) and the corresponding electrolyte. All cells were assembled in an argon-filled glove box with an oxygen and water content of less than 1.0 ppm and their electrochemical tests were performed in a Maccor 4000 battery test system.

[0257] III.2) NCM622 / graphite and NCM811 / graphite soft pack batteries

[0258] The positive electrode used for the electrochemical cycling test in the soft pack battery was prepared by coating a slurry containing the cathode active material suspended in N-methyl-2-pyrrolidone (NMP), carbon black and polyvinylidene fluoride (PVdF) binder on an aluminum foil (thickness = 17 μm) using a roll coater. The electrode tape was dried in a hot air chamber and further dried at 130°C in vacuum for 8 hours, and the electrode was pressed using a roller press. The cathode active material used was Li(Ni 0.8 Co 0.1 Mn 0.1 )O2(NCM811) or Li(Ni 0.6 Co 0.2 Mn 0.2 )O2 (NCM622). For the negative electrode, an aqueous slurry was prepared by mixing graphite and carbon black with CMC (carboxymethyl cellulose) and SBR (styrene / butadiene rubber). The resulting slurry was applied to a copper foil (thickness = 9 μm) by using a roll coater and dried in a hot air chamber (80-120°C). The loading of the resulting electrode was found to be 10 mg / cm 2 The electrodes were pressed to an approximate thickness of 72 μm by a roller press. Pouch cells (250 mAh) including NCM positive electrodes and graphite negative electrodes and a separator stacked between the cathode and anode were assembled in an Ar-filled glove box. All cells were then filled with electrolytes as described in Table 2 in an Ar-filled glove box with oxygen and water content less than 1.0 ppm and subjected to their electrochemical testing in a Maccor 4000 battery test system.

[0259] IV. Evaluation of Electrochemical Cells

[0260] IV.1) Evaluation of cycling and cell resistance in HE-NCM / graphite 2032 coin full cells at 25°C

[0261] The battery was charged at 25° C. with a constant current of 0.067 C to a voltage of 4.7 V and discharged at a constant current of 0.067 C to a discharge voltage of 2.0 V (first activation cycle).

[0262] The battery was then immediately charged to a voltage of 4.6V at a constant current of 0.1C at 25°C. The battery was further charged at 4.6V until the current reached a value of 0.05C and then discharged to a discharge voltage of 2.0V at a constant current of 0.1C (second cycle). The same procedure as the second cycle was repeated once (cycle 3). The battery was then charged to a voltage of 4.6V at a constant current of 0.1C and then discharged to a discharge voltage of 2.0V at a constant current of 0.1C (cycle 4). The charging capacity of this cycle was used as a reference value for subsequent cycles (cycle 5), in which the battery was charged at a constant current of 0.1C until 40% (40% SOC) of the charging capacity of cycle 5. After the battery reached 40% SOC, DC internal resistance (DCIR) measurement was performed by applying a 0.2C current interruption within 10 seconds.

[0263] In cycles 6-7, the battery was charged at 25° C. with a constant current of 0.2 C to a voltage of 4.6 V. The battery was further charged at 4.6 V until the current reached a value of 0.05 C, and then discharged at a constant current of 0.5 C to a discharge voltage of 2.0 V. The battery was then charged at a constant current of 0.7 C to a voltage of 4.6 V, charged at 4.6 V until the current reached a value of 0.05 C, and then, while maintaining this charging condition constant, the battery was discharged at a constant current of 1 C (2 times, cycles 8-9), 2 C (2 times, cycles 10-11) and 3 C (2 times, cycles 12-13) to a discharge voltage of 2.0 V. The discharge capacity recorded in cycle 13 is expressed as a percentage of the discharge capacity obtained in cycle 3 (see the discharge capacity ratio 3C / 0.1C (%) in Table 3).

[0264] After changing the discharge rate, long-term cycling was performed by charging the battery at a constant current of 0.7C to a voltage of 4.6V, charging at 4.6V until the current reached a value of 0.05C and discharging at a constant current of 1C to a discharge voltage of 2.0V (cycle 14). The discharge capacity measured for cycle 14 was recorded as the initial discharge capacity at 1C. This charging and discharging procedure was repeated at least 200 times or until the measured charge capacity was less than 70% of the charge capacity of cycle 14. During the long-term cycling test, DC internal resistance (DCIR) measurements were performed at 40% SOC every 100 cycles. The latter was performed every 100 1C cycles by repeating the cycle sequence described for cycles 2-5. The results from each example are shown in Table 3.

[0265] Table 3. Results obtained from HE-NCM / graphite battery cycle tests at 25°C

[0266]

[0267] The discharge capacity and cell resistance of cells containing oligomeric silylphosphonates are comparable to or significantly better than the values ​​for monomeric additives, wherein the oligomeric additives have the advantage of being less volatile. This facilitates a constant concentration of the additive during the preparation and handling of the electrolyte composition and during the filling of the electrolyte composition into the cell. A vacuum is usually applied to the cell before filling the cell with the liquid electrolyte to ensure good filling of the cell with the liquid electrolyte composition and good wetting of all components.

[0268] IV.2 Evaluation of the cycling performance of pouch cells containing NCM 622 and 811 cathodes and graphite anodes

[0269] IV.2.1) Formation

[0270] The prepared pouch full cells containing NCM 622 or NCM 811 cathode and graphite anode were charged at a constant current of 0.1 C to a voltage of 3.7 V or up to 2 hours. The cells were then stored at 45°C for 17 hours before degassing and initial volume measurements were performed via Archimedes measurement in water at ambient temperature.

[0271] IV.2.2) High temperature storage of pouch full cells containing NCM622 / / graphite and NCM811 / / graphite at 60°C

[0272] After completing the formation procedure, the battery was charged to 4.2V at ambient temperature and then stored at 60°C for 14 days. The amount of gas (mL) generated during storage was determined by Archimedes measurement in water at ambient temperature and the results are summarized in Table 6. The final charge (CCCV charge, 0.2C, 4.2V, 0.015C cutoff) and discharge (CC discharge, 0.2C, 3.0V cutoff) capacities were measured after the storage test. The capacity retention after cycling is expressed as the ratio of the final and initial discharge capacities. The battery resistance after cycling was determined by charging the battery to 50% SOC and performing a DC internal resistance (DCIR) measurement by applying a current interruption. The results from each example are shown in Tables 4 and 5. Compared with the control battery, the electrochemical cell of the present invention shows significantly lower gas generation.

[0273] Table 4. Results from NCM-622 / graphite battery storage tests at 60°C

[0274]

[0275]

[0276] Table 5. Results from NCM-811 / graphite battery storage tests at 60°C

[0277]

Claims

1. An electrolyte composition comprising (i) at least one aprotic organic solvent; (ii) at least one conductive salt; (iii) at least one silylphosphonate having the structure of formula (I): in T is selected from p is 1, 2, 3, 4, 5 or 6 and one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl; R 1 is independently selected at each occurrence from H, F, Cl, R 4 , OR 4 、OSi(R 5 )3、OSi(OR 4 )3 and OP(O)(OR 4 )R 5 ; R 4 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to a Si atom or an O atom may be replaced by O; R 3 and R 5 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the P atom may be replaced by O; and (iv) optionally one or more additives.

2. The electrolyte composition according to claim 1, wherein the silylphosphonate comprises the structure of formula (II): in Q 1 is a chemical bond or a monomer or oligomeric group containing one or more monomer units of formula (II.1), and Q 2 is a chemical bond or a monomer or oligomeric group containing one or more monomer units of formula (II.2): in T* is independently Si or Si-(CH2) at each occurrence p -Si, wherein p is an integer from 0 to 6, one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl, and When T* is Si, q 1 is an integer between 0 and 2, q 2 is an integer from 0 to 2, and q 1 +q 2 =2, where T* is Si-(CH2) p -Si case, q 1 is an integer from 0 to 4, q 2 is an integer from 0 to 4, and q 1 +q 2 =4; and -* is the continuation of the silylphosphonate backbone through branching.

3. The electrolyte composition according to claim 2, wherein the silylphosphonate has formula (III): in R 6 and R 7 Independently selected from R 8 、Si(OR 8 )3 and Si(R 9 )3; R 8 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to an O atom or Si atom may be replaced by O; and R 9 is independently selected at each occurrence from H, F, Cl, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the O atom may be replaced by O.

4. The electrolyte composition according to any one of claims 2 or 3, wherein the silylphosphonate has formula (IV): in r 1 and r 2 are independently integers from 0 to 300.

5. The electrolyte composition according to any one of claims 3 or 4, wherein R 6 and R 7 Independently selected from C1-C 10 Alkyl, Si(OC1-C 10 Alkyl)3 and Si(R 9 )3, where R 9 is independently selected at each occurrence from H, F, Cl and Cl-C 10 alkyl.

6. The electrolyte composition according to any one of claims 1 to 5, wherein R 1 is independently selected at each occurrence from H, F, Cl, Cl-C 10 Alkyl and OC1-C 10 Alkyl, wherein the alkyl may be substituted by one or more substituents selected from CN and F and wherein one or more CH2 groups of the alkyl which are not directly bonded to a Si atom or an O atom may be replaced by O.

7. The electrolyte composition according to any one of claims 1 to 6, wherein R 3 is independently selected at each occurrence from H and C1-C 10 Alkyl groups which may be substituted by one or more F and / or CN and in which one or more CH2 groups of the alkyl group which are not directly bonded to the P atom may be replaced by O.

8. An electrolyte composition according to any one of claims 1 to 7, wherein the structure of formula (I) is selected from:

9. An electrolyte composition according to any one of claims 1 to 8, wherein the aprotic organic solvent (i) is selected from the group consisting of fluorinated and non-fluorinated cyclic and acyclic organic carbonates, fluorinated and non-fluorinated ethers and polyethers, fluorinated and non-fluorinated cyclic ethers, fluorinated and non-fluorinated cyclic and acyclic acetals and ketals, fluorinated and non-fluorinated orthocarboxylates, fluorinated and non-fluorinated cyclic and acyclic esters and diesters of carboxylic acids, fluorinated and non-fluorinated cyclic and acyclic sulfones, fluorinated and non-fluorinated cyclic and acyclic nitriles and dinitriles, fluorinated and non-fluorinated cyclic and acyclic phosphates, and mixtures thereof.

10. The electrolyte composition according to any one of claims 1 to 9, wherein the at least one aprotic organic solvent (i) comprises at least one solvent selected from fluorinated and non-fluorinated ethers and polyethers, fluorinated and non-fluorinated cyclic and acyclic organic carbonates and mixtures thereof.

11. The electrolyte composition according to any one of claims 1 to 10, wherein the at least one conductive salt (ii) is selected from lithium salts.

12. The electrolyte composition according to any one of claims 1 to 11, comprising 0.01 to 10 wt% of silylphosphonate, based on the total weight of the electrolyte composition.

13. Use of a silylphosphonate having the structure of formula (I) in an electrolyte composition for an electrochemical cell: in T is selected from p is an integer from 0 to 6 and one or more CH2 groups of (CH2)p may be replaced by O and one or more H of (CH2)p may be replaced by C1-C4 alkyl; R 1 is independently selected at each occurrence from H, F, Cl, R 4 , OR 4 、OSi(R 5 )3、OSi(OR 4 )3 and OP(O)(OR 4 )R 5 ; R 4 In each occurrence, independently selected from C1-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl, which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of alkyl, alkenyl and alkynyl groups which are not directly bonded to a Si atom or an O atom may be replaced by O; R 3 and R 5 independently selected at each occurrence from H, F, Cl-C 10 Alkyl, C3-C7 (hetero)cycloalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C5-C7 (hetero)aryl and C6-C 13 (Hetero)aralkyl which may be substituted by one or more substituents selected from CN and F and in which one or more CH2 groups of the alkyl, alkenyl and alkynyl groups which are not directly bonded to the P atom may be replaced by O.

14. An electrochemical cell comprising the electrolyte composition according to any one of claims 1 to 12.

15. The electrochemical cell according to claim 14, wherein the electrochemical cell is a lithium battery, a double layer capacitor or a lithium ion capacitor.

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