Polymer electrolyte

Abstract

The present invention provides a polymer electrolyte suitable for a lithium ion secondary battery, obtained by a reaction between at least one polyether polymer [polymer (P)], said polymer (P) comprising: at least 70.0 mol% of oxyethylene units; 0.0 mol% to 10.0 mol% of oxypropylene units; and 1.00 mol% to 4.0 mol% of repeating units derived from at least one monomer and at least one polysiloxane compound. The at least one polysiloxane compound is grafted onto the at least one polymer (P) by a reaction of at least a part of the -CH=CH2 moiety of the monomer (M) with the H-Si moiety of the polysiloxane compound.

Description

Technical Field

[0001] This invention relates to polymer electrolytes suitable for lithium-ion secondary batteries. Background Technology

[0002] Polymer electrolytes are an interesting alternative to liquid electrolytes in batteries. In this context, polyethylene oxide (PEO)-based electrolytes have been extensively studied in the literature.

[0003] For example, Ruoyuan Tao et al. disclosed a positive electrode in J. Appl. Electrochem. 35, 163-168 (2005) comprising poly(ethylene oxide) and lithium bis(trifluoromethanesulfonyl)imide (Li(N(SO2CF3)2), also known as LiTFSI). PEO and LiTFSI were dissolved in acetonitrile to prepare an electrolyte solution. The positive electrode active material was then added to the electrolyte solution.

[0004] US 7,585,934 B2 discloses the use of EO / PO / AGE and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, Li(N(SO2CF3)2)) as solid polymer electrolyte membranes. The document discloses a copolymerization procedure for EO, ​​PO, and AGE in working examples. Specifically, LiTFSI is added in the form of a Li salt to a polyether polymer composition comprising the EO / PO / AGE copolymer in an amount such that the ratio of (moles of lithium atoms in the electrolyte salt) to (moles of oxygen atoms in the polyether polymer) is 0.05.

[0005] Despite recent advancements in this field, capacity leakage remains a problem when PEO-based solid electrolytes are used in batteries. Capacity leakage is a phenomenon in which the electrolyte acquires electronic conductivity, causing an electronic current to leak from the anode to the cathode.

[0006] Therefore, there is a need for improved polymer electrolytes, especially polymer electrolytes that reduce capacity leakage when used in batteries. Summary of the Invention

[0007] The inventors have surprisingly discovered that an improved polymer electrolyte can be provided to meet the above-mentioned needs.

[0008] Therefore, the main objective of this invention is a polymer electrolyte suitable for lithium-ion secondary batteries, which is obtained through a reaction between the following substances:

[0009] i. At least one polyether polymer [hereinafter referred to as polymer (P)], said polymer (P) comprising:

[0010] a) At least 70.0 mol% of ethylene oxide units (EO);

[0011] b) 0.0 mol% to 10.0 mol% of oxypropylene units (PO); and

[0012] c) 1.00 mol% to 4.0 mol% of repeating units of at least one monomer derived from general formula (I) or general formula (II) [monomer (M) hereinafter]:

[0013]

[0014] or

[0015]

[0016] in

[0017] - Each of R1 and R2 is either the same as or different from each other, and is C each time it appears. 1-6 Alkyl, wherein the C 1-6 Alkyl groups are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR8 are used, wherein each R8 is the same as or different from each other and is independently selected from the group hydrogen and C each time it appears. 1-4 Alkyl; n is an integer, either 0, 1, or 2;

[0018] Each of -X is a leaving group selected from halide ions, trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, and methanesulfonate.

[0019] and

[0020] ii. At least one polysiloxane compound having formula (III):

[0021]

[0022] in

[0023] Each of R3, R4, R5, R6, and R7 is either the same as or different from each other, and is independently selected from C each time it appears. 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 alkoxy, heterocyclic group, wherein the C 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 The alkoxy group and heterocyclic group are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR9 are used, wherein each R9 is the same as or different from each other and is independently selected from hydrogen, C, and D in each occurrence. 1-4Alkyl and hydroxyl protecting groups,

[0024] -m is an integer of at least 3; and

[0025] The at least one polysiloxane compound having formula (III) is grafted onto the at least one polymer (P) by reacting at least a portion of the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III). Detailed Implementation

[0026] Polymer electrolyte

[0027] As used herein and in the claims, the term "comprising" should not be construed as limited to the manner listed thereafter; it does not exclude other elements or steps. It should be interpreted as specifying the presence of the mentioned feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, or components or groups thereof. Therefore, the scope of the expression "a composition comprising component A and component B" should not be limited to compositions consisting solely of components A and B. This means that, with respect to the present invention, the only relevant components of the composition are A and B. Therefore, the terms "comprising" and "including" encompass the more restrictive terms "consistently composed of" and "composed of".

[0028] As used herein, the terms “optional” or “optionally” mean that an event or situation described below may or may not occur, and the description includes instances where said event or situation occurs and instances where said event or situation does not occur.

[0029] The inventors have surprisingly discovered that when the polymer electrolyte according to the invention is used in batteries, particularly in solid-state lithium-ion batteries, capacity leakage is reduced, resulting in improved battery performance, as demonstrated in the working examples.

[0030] In the context of this invention, the expression "at least one polyether polymer [polymer (P) hereinafter]" is intended to mean one or more polymers (P). Similarly, the expression "at least one polysiloxane compound having formula (III)" is intended to mean one or more polysiloxane compounds having formula (III).

[0031] In the remainder of this document, for the purposes of this invention, the terms “polymer (P)” and “polysiloxane compound having formula (III)” shall be understood as both plural and singular.

[0032] As used herein, the term "alkyl" has the broadest meaning as commonly understood in the art and may include portions that are straight-chain or branched or combinations thereof.

[0033] The term "alkyl," alone or in combination, refers to a group derived from straight-chain or branched alkane, such as C... F-G Alkyl groups are defined as straight-chain or branched alkyl groups having F to G carbon atoms, such as C 1-4 Alkyl is defined as a straight-chain or branched alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, 1-propyl, 2-propyl (isopropyl), 1-butyl, 2-butyl, 2-methyl-2-propyl (tert-butyl), and 2-methyl-1-propyl (isobutyl).

[0034] The term "cycloalkyl," alone or in combination, refers to a group derived from cyclic alkane, such as C L-M Cycloalkyl is defined as a cyclic alkyl group having L to M carbon atoms, such as C 3-6 Cycloalkyl is defined as a cyclic alkyl group having 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.

[0035] The term "aryl," alone or in combination, refers to a phenyl, naphthyl, or anthracene group, optionally fused with a cycloalkyl or heterocyclic carbocyclic ring having preferably 5-7, more preferably 5-6 ring members, and / or optionally substituted with 1 to 5 groups or substituents. The aryl group may be optionally substituted, whereby the substituent is connected to the aryl group at one point, or whereby the substituent is connected to the aryl group at two points to form a bicyclic system, such as benzodioxane, benzodioxane, or benzimidazole.

[0036] The term "heterocyclic group," alone or in combination, refers to a cyclic alkane-derived group in which at least one carbon atom is independently substituted by a heteroatom selected from oxygen, nitrogen, and sulfur, such as pyrrolidine, piperidine, or morpholine.

[0037] The term "alkoxy group," alone or in combination, refers to a group derived from straight-chain or branched alkane compounds, wherein the carbon atom carrying the group is replaced by an oxygen atom. The alkoxy moiety has a -0-R... x Structure, where R x It is an alkyl group.

[0038] The term "alkyldiyl" refers, alone or in combination, to a divalent group derived from a straight-chain or branched alkyl group.

[0039] As described above, the polymer (P) contains

[0040] a) Repeating units of at least 70.0 mol% ethylene oxide (EO);

[0041] b) 0.0 mol% to 10.0 mol% of oxypropylene units (PO); and

[0042] c) 1.00 mol% to 4.0 mol% of repeating units of at least one monomer derived from general formula (I) or general formula (II) [monomer (M) hereinafter]:

[0043]

[0044] or

[0045]

[0046] in

[0047] - Each of R1 and R2 is either the same as or different from each other, and is C each time it appears. 1-6 Alkyl, wherein the C 1-6 Alkyl groups are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR8 are used, wherein each R8 is the same as or different from each other and is independently selected from the group hydrogen and C each time it appears. 1-4 Alkyl; n is an integer, either 0, 1, or 2;

[0048] Each of -X is a leaving group selected from halide ions, trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, and methanesulfonate.

[0049] Therefore, at least 70.0 mol%, preferably at least 80.0 mol%, preferably at least 85.0 mol%, preferably at least 90.0 mol%, more preferably at least 92.0 mol%, and more preferably at least 94.0 mol% of the repeating unit of the polymer (P) is the oxyethylene repeating unit (EO).

[0050] It should also be understood that at most 99.0 mol%, more preferably at most 98.5 mol%, and even more preferably at most 98.0 mol% of the repeating units of the polymer (P) are EO units.

[0051] In a preferred embodiment, the polymer (P) comprises at least 80.0 mol% and at most 99.0 mol%, preferably at least 90.0 mol% and at most 98.5 mol%, preferably at least 92.0 mol% and at most 98.5 mol% of EO units, and preferably at least 94.0 mol% and at most 98.5 mol% of EO units.

[0052] When oxypropylene repeating units (PO) are present in polymer (P), the repeating units of polymer (P) are up to 10.0 mol%, more preferably up to 6.0 mol%, even more preferably up to 5.0 mol%, even more preferably 4.0 mol%, even more preferably up to 3.0 mol%, which are PO units.

[0053] Advantageously, the polymer (P) contains at least 0.1 mol%, or at least 0.5 mol%, or at least 1.0 mol% of PO units.

[0054] In a preferred embodiment, the polymer (P) comprises at least 0.5 mol% and at most 6.0 mol%, or at least 0.5 mol% and at most 5.0 mol%, or at least 0.5 mol% and at most 4.0 mol%, or at least 1.0 mol% and at most 4.0 mol%, or at least 1.0 mol% and at most 3.0 mol% of PO units.

[0055] The presence of PO units reduces the crystallinity of the polymer (P), which improves its ionic conductivity.

[0056] For the purposes of this invention, the term "oxypropylene (PO)" is intended to refer to the formula -O-CH2-CH2-CH2- or -O-CH2-CH(CH3)-, preferably –O-CH2-CH(CH3)-.

[0057] Preferably, at least 1.2 mol%, or at least 1.5 mol%, or at least 1.8 mol%, or at least 2.2 mol% of the repeating units of the polymer (P) are repeating units derived from monomers (M) of general formula (I) or general formula (II) as detailed above.

[0058] It should also be understood that at most 4.0 mol%, more preferably at most 3.5 mol%, and even more preferably at most 3.0 mol% of the repeating units of the polymer (P) are repeating units derived from the monomer (M) of the general formula (I) or general formula (II) as detailed above.

[0059] In a preferred embodiment, the polymer (P) comprises at least 1.2 mol% and at most 4.0 mol%, preferably at least 1.5 mol% and at most 3.5 mol%, preferably at least 1.5 mol% and at most 3.0 mol% of repeating units derived from at least one monomer (M) of general formula (I) or general formula (II) as detailed above.

[0060] When the repeating unit in the polymer (P) is derived from the monomer (M) of general formula (II), it should be understood that the repeating unit is the result of the ring-opening polymerization of the epoxide moiety.

[0061] When the repeating unit in the polymer (P) is derived from a monomer (M) of general formula (I) (where X is an acyl chloride or acyl bromide), it should be understood that the repeating unit can be the result of a process in which the monomer (M) reacts with, for example, the terminal OH group of the EO unit or PO unit of a dihydroxy-terminated polyethylene oxide (or a PEO-co-PPO copolymer) to form an ester moiety.

[0062] When the repeating unit in the polymer (P) is derived from a monomer (M) of general formula (I) (where X is trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, or methanesulfonate), the repeating unit can be the result of a process in which, in the presence of a strong base (such as NaH), the monomer (M) undergoes a Williamson-type reaction with, for example, the terminal OH group of the EO or PO unit of a dihydroxy-terminated polyethylene oxide (or PEO-co-PPO copolymer), thereby forming an ether moiety. This is followed by alkoxide formation and subsequent substitution of the X moiety of the monomer (M).

[0063] These polymerization reactions are known in the art and are specifically described by H.-Q.Xie, J.-S.Guo, G.-Q.Yu and J.Zu in Journal of Applied Polymer Science 2001, 80, 2446.

[0064] Preferably, each of the X in the monomer (M) of general formula (I) is a halide ion, more preferably a halide ion selected from chloride ions, bromide ions and iodide ions.

[0065] According to a preferred embodiment of a polymer electrolyte suitable for lithium-ion secondary batteries, the monomer (M) has formula (II).

[0066]

[0067] in

[0068] - Each of R1 and R2 is either the same as or different from each other, and is C each time it appears. 1-2 Alkyl, and n is an integer 0 or 1, preferably n is 1.

[0069] In another preferred embodiment of the polymer electrolyte suitable for lithium-ion secondary batteries, the monomer (M) according to the invention is selected from those of formulas (Ia) to (If) and (IIa) to (IIe):

[0070]

[0071] Wherein X is selected from halide ions, trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate and methanesulfonate, acyl chloride, and acyl bromide. Preferably, X is a halide ion, more preferably a halide ion selected from chloride ions, bromide ions, and iodide ions. Even more preferably, X is a bromide ion.

[0072] More preferably, the monomer (M) according to the invention is a compound selected from those monomers of formula (Ia) to (If).

[0073] Most preferably, the monomer (M) is a compound of formula (Ia).

[0074] According to a preferred embodiment of the polymer electrolyte suitable for lithium-ion secondary batteries, the polymer (P) is essentially composed of the following substances:

[0075] a) 94.0 mol% to 98.5 mol% of repeating EO units;

[0076] b) 0.5 mol% to 3.0 mol% of repeating PO units; and

[0077] c) 1.0 mol% to 3.0 mol% of repeating units derived from monomer (M) of general formula (II):

[0078]

[0079] Each of R1 and R2 may be the same as or different from each other and is a C1-2 alkyldiyl group each time it appears, and n is an integer 0 or 1, preferably n is 1. It should be understood that chain defects or very small amounts of other units may be present, and it should be understood that these latter do not substantially modify the properties of the polymer (P).

[0080] Preferably, the polymer (P) as detailed above has a weight-average molecular weight (Mw) of at least 10,000 g / mol, more preferably at least 20,000 g / mol, even more preferably at least 40,000 g / mol, and even more preferably at least 50,000 g / mol.

[0081] It should be understood that the polymer (P) as detailed above preferably has a Mw of up to 150,000 g / mol, more preferably up to 100,000 g / mol.

[0082] In a preferred embodiment, the polymer (P) as detailed above has a Mw of at least 10,000 g / mol and at most 150,000 g / mol, preferably at least 20,000 g / mol and at most 150,000 g / mol, more preferably at least 40,000 g / mol and at most 100,000 g / mol, and even more preferably at least 50,000 g / mol and at most 100,000 g / mol.

[0083] According to the present invention, Mw is measured by GPC with PEO standard calibration. Therefore, the Mw mentioned is the PEO equivalent.

[0084] Alternatively and even more preferably, the polymer (P) as detailed above has a number-average molecular weight of at least 10,000 g / mol, more preferably at least 20,000 g / mol, even more preferably at least 40,000 g / mol, even more preferably at least 50,000 g / mol.

[0085] It should be understood that the polymer (P) as detailed above preferably has a Mn content of up to 150,000 g / mol, more preferably up to 100,000 g / mol.

[0086] In a preferred embodiment, the polymer (P) as detailed above has at least 10,000 g / mol and at most 150,000 g / mol, preferably at least 20,000 g / mol and at most 150,000 g / mol, more preferably at least 40,000 g / mol and at most 100,000 g / mol, and even more preferably at least 50,000 g / mol and at most 100,000 g / mol of Mn.

[0087] According to the present invention, Mn is measured by GPC with PEO standard calibration. Therefore, the Mn mentioned is the PEO equivalent.

[0088] Preferably, the polymer (P) according to the invention is a random or block copolymer, more preferably a random copolymer.

[0089] Preferably, the polymer (P) according to the invention is linear or branched, more preferably linear.

[0090] The particularly preferred polymer (P) is a linear random copolymer, wherein it is noteworthy that the main chain can be described according to formula (IV):

[0091]

[0092] In the polymer (P) of formula (IV), the ratio of o to q (o / q) is between 25 and 100, or between 35 and 75, or between 40 and 60. In the polymer (P) of formula (IV), the ratio of p to q (p / q) is advantageously between 0.05 and 1.50, preferably between 0.10 and 1.00, and more preferably between 0.20 and 0.60.

[0093] It is worth noting that this type of polymer (P) can be marketed under a trade name. The CP-A series was purchased from Meisei Chemicalworks Ltd.

[0094] As described, a polysiloxane compound having formula (III) will be used.

[0095]

[0096] in

[0097] Each of R3, R4, R5, R6, and R7 is either the same as or different from each other, and is independently selected from C each time it appears. 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 alkoxy, heterocyclic group, wherein the C 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 The alkoxy group and heterocyclic group are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR9 are used, wherein each R9 is the same as or different from each other and is independently selected from hydrogen, C, and D in each occurrence. 1-4 Alkyl and hydroxyl protecting groups, and

[0098] -m is an integer of at least 3;

[0099] The monomer (M) is grafted onto the polymer (P) as detailed above by reacting at least a portion of the -CH=CH2 portion of the monomer (M) with the H-Si portion of a polysiloxane compound having formula (III).

[0100] Preferably, each of R3 and R4 is the same as or different from each other and independently represents C each time it occurs. 1-6 Alkyl, more preferably, each of R3 and R4 is the same as or different from each other and is methyl, ethyl, propyl or isopropyl each time it appears, even more preferably, each of R3 and R4 is the same as or different from each other and is methyl each time it appears.

[0101] Preferably, each of R5 and R6 is the same as or different from each other and is independently selected from C each time it appears. 1-4 alkyl or phenyl, wherein the C 1-4 Alkyl groups are optionally selected from halide ions, C 1-4 One or more substituents of alkyl or CF3 are used for substitution. More preferably, each of R5 and R6 is the same as or different from each other and is methyl, ethyl, propyl or isopropyl each time it appears. Even more preferably, each of R5 and R6 is the same as or different from each other and is methyl each time it appears.

[0102] Preferably, each R7 is C 1-6 Alkyl, more preferably, each R7 is C 1-4 Alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0103] Preferably, m is an integer of at least 5, more preferably at least 7, or even more preferably at least 8.

[0104] It should also be understood that m is preferably an integer of at most 1000, more preferably at most 500, even more preferably at most 100, even more preferably at most 20, even more preferably at most 15.

[0105] In a preferred embodiment of the invention, m is an integer of at least 5 and at most 1000, preferably at least 5 and at most 500, more preferably at least 5 and at most 100, even more preferably at least 5 and at most 20, even more preferably at least 7 and at most 20, even more preferably at least 8 and at most 15.

[0106] In the context of this invention, it should be understood that the -CH=CH2 moiety of monomer (M) can react with the H-Si moiety of a polysiloxane compound having formula (III) as detailed above, in order to obtain a covalent bond between the two moieties. Such reactions are commonly referred to as hydrosilylation reactions. It should also be understood that the reactions may involve the formation of one or more intermediates, including metal complexes and σ complexes.

[0107] For the reaction of at least a portion of the -CH=CH2 portion of the monomer (M) as detailed above with the H-Si portion of the polysiloxane compound having formula (III) as detailed above, several techniques known in the art can be successfully used.

[0108] It is worth noting that the polymer (P) as detailed above and the polysiloxane having formula (III) as detailed above can react significantly in the molten state; melt compounding machines such as extruders, melt kneaders or other devices can be advantageously used for this purpose.

[0109] It is worth noting that the polymer (P) as detailed above and the polysiloxane having formula (III) as detailed above can react in solution; according to this embodiment, the polymer (P) and the polysiloxane having formula (III) as detailed above are at least partially dissolved in a solvent. Dissolution can be achieved at room temperature or preferably by heating to at least 70°C, more preferably at least 80°C, and even more preferably at the reflux temperature of the solvent. The choice of solvent is not critical, provided that it effectively solvates both the polymer (P) as detailed above and the polysiloxane having formula (III) without interfering with the hydrosilylation reaction. Generally, organic solvents are preferred. Among these organic solvents, benzene, toluene, xylene, methyl isopropylbenzene, etc. are worth mentioning.

[0110] Furthermore, it is worth noting that the polymer (P) as detailed above and the polysiloxane having formula (III) as detailed above can react in the presence of a catalyst, especially a hydrosilylation catalyst.

[0111] Such hydrogenation silylation catalysts are known in the art. Of particular note are ruthenium, platinum, or rhodium-based catalysts, such as, in particular, Karstedt, Wilkinson, and Speier catalysts, and mixtures thereof.

[0112] In the context of this invention, the expression “reaction of at least a portion of the -CH=CH2 of monomer (M) with the H-Si portion of a polysiloxane compound having formula (III)” means that only a portion or all of the CH=CH2 of monomer (M) can react with the H-Si portion of a polysiloxane compound having formula (III).

[0113] Preferably, the polysiloxane compound having formula (III) is grafted onto the polymer (P) as detailed above by reacting the -CH=CH2 portion of a monomer (M) having formula (III) with the H-Si portion of a polysiloxane compound having formula (III).

[0114] It should also be understood that the polysiloxane compound having formula (III) as detailed above can be grafted onto the polymer (P) as detailed above by reacting the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III).

[0115] In a preferred embodiment, the polysiloxane compound having formula (III) described above is grafted onto the polymer (P) described above by reacting the -CH=CH2 portion of a monomer (M) with the H-Si portion of a polysiloxane compound having formula (III).

[0116] This reaction can be monitored using known analytical methods, such as, in particular, by using GPC or 1 The H-NMR method is described in the experimental section.

[0117] Preferably, the polymer electrolyte is obtained by a reaction between the at least one polymer (P) and at least 6% by weight, at least 7% by weight, or at least 8% by weight of the at least one polysiloxane compound relative to the total amount of the at least one polymer (P) and the at least one polysiloxane compound.

[0118] Preferably, the polymer electrolyte is obtained by a reaction between the at least one polymer (P) and at most 27% by weight, at most 25% by weight, or at most 22% by weight of the at least one polysiloxane compound relative to the total amount of the at least one polymer (P) and the at least one polysiloxane compound.

[0119] In a preferred embodiment, the polymer electrolyte is obtained by a reaction between the at least one polymer (P) and at least 6% by weight and at most 27% by weight, or at least 7% by weight and at most 25% by weight, or at least 8% by weight and at most 22% by weight of the at least one polysiloxane compound relative to the total amount of the at least one polymer (P) and the at least one polysiloxane compound.

[0120] Example

[0121] The following examples are intended to further illustrate the invention, but not to limit the scope of the invention.

[0122] 1. Example 1

[0123] 1.1. Materials and Methods

[0124] Unless otherwise stated, use the following materials as described below.

[0125] The random polymer (P) was purchased from Meisei Chemical Works Ltd under the trade name CP series CP-A. Alternatively, the polymer (P) could be prepared by following the procedure disclosed in H.-Q. Xie, J.-S. Guo, G.-Q. Yu and J. Zu, Journal of Applied Polymer Science 2001, 80, 2446.

[0126] Monohydride-terminated polydimethylsiloxane (SiH-terminated PDMS, M w =850g / mol) purchased from Gelest, Inc.

[0127] The silica-supported Karsted catalyst was prepared according to QJMiao, Z.-P. Fang and GPCai, Catalysis Communications 2003, 4, 637-639.

[0128] LiTFSI (lithium bis(trifluoromethanesulfonyl)imide, based on 99.95% trace metal) was purchased from Sigma-Aldrich.

[0129] Anhydrous acetonitrile 99.8% by weight was purchased from Sigma-Aldrich.

[0130] Timcal Super P is a conductive carbon black powder manufactured by Imerys Graphite & Carbon (CAS No. 1333-86-4).

[0131] Polyethylene oxide (with M of 1,000,000) w The PEO was purchased from Alfa Aesar.

[0132] Recorded at room temperature on a JEOL JNM ECZ 500MHz NMR spectrometer 1 H-spectroscopy. The polymer sample was dissolved in CDCl3 and the internal standard was optimized using tetramethylsilane (TMS).

[0133] Inductively coupled plasma (ICP) measurements were performed using an Agilent 720 ICP-OES (Agilent Technologies, https: / / www.agilent.com / cs / library / brochures / 5990-6497EN%20720-725_ICP-OES_LR.pdf). One gram of powder sample was dissolved in 50 mL of high-purity hydrochloric acid (at least 37% by weight HCl relative to the total weight of the solution) in an Erlenmeyer flask. The flask was covered with a watch glass and heated on a hot plate at 380°C until the powder was completely dissolved. After cooling to room temperature, the solution in the Erlenmeyer flask was poured into a first 250 mL volumetric flask. The first volumetric flask was then filled with deionized water to the 250 mL mark, followed by a complete homogenization process (first dilution). A suitable amount of solution was taken from the first volumetric flask using a pipette and transferred to a second 250 mL volumetric flask for a second dilution. The second volumetric flask was then filled with internal standard and 10% hydrochloric acid up to the 250 mL mark and homogenized. Finally, this solution was used for ICP measurement.

[0134] 1.2. Preparation of Polymer Electrolytes

[0135] The following procedure is followed to react polymer (P), a random linear copolymer characterized as shown in Table 1, with monohydride-terminated polydimethylsiloxane (SiH-terminated PDMS) via hydrosilylation:

[0136] Table 1

[0137] EO mole% 97.5％ PO mole % 0.5％ mol% of allyl glycidyl ether (AGE) 1.9％ Mn (GPC calibrated using PEO standard) 72,000 g / mol

[0138] A mixture containing 2.0 g of polymer (P) and 0.36 g of SiH-terminated PDMS was added to 50 mL of benzene containing 20 mg of silica-supported Karsted catalyst, and heated at 90 °C for 48 hours under a nitrogen atmosphere.

[0139] The heated mixture was filtered through diatomaceous earth to remove the solid catalyst, and then placed under reduced pressure to remove the solvent. PDMS was grafted onto the polymer (P) by reacting the -CH=CH2 of 50 mol% AGE units with the H-Si moiety of PDMS.

[0140] Successful grafting 1 Confirmed by H-NMR and GPC (gel permeation chromatography).

[0141] Polymer (P): 1 H-NMR (TMS, CDCl3, 500MHz): δ (ppm) 1.2 (d, CH3 in PO unit), 4 (m, -OC in AGE unit) H2 -CH=CH2), 5.2(m, C of AGE unit H2 =CH-), 5.8(m, AGE unit of -C) H =CH2).

[0142] Monohydride PDMS: 1 H-NMR (TMS, CDCl3, 500MHz): δ (ppm) 0.5 (m, -Si-C H 2-CH2-), 0.9(t, C H 3-CH2-), 1,3(br,-Si-CH2-C H 2-C H2 -CH3), 4.8(m, H -Si-).

[0143] Polymer electrolyte: 1 H-NMR (TMS, CDCl3, 500MHz): δ (ppm): 0.5 (br, PDMS-Si-C H 2-CH2-), 0.9 (br, C of PDMS) H3-CH2-), 1.1(d, CH3 of PO unit), 1.2(br, -Si-CH2-C of PDMS) H 2-C H2 -CH3), 1,4(br, -OCH2-C H2 -CH2-Si-).

[0144] The presence of a broad peak at 1.4 ppm and the absence of peaks attributed to H-Si in the polyelectrolyte 1H-NMR spectrum confirms successful hydrosilylation.

[0145] Figure 1 The GPC elution curves of the polymer electrolyte, polymer (P), and polysiloxane prepared as described above are shown.

[0146] Compared to polymer (P), the polymer electrolyte has a shorter elution time, which indicates that the polymer electrolyte has a higher molecular weight than polymer (P), thus PDMS was successfully grafted onto polymer (P).

[0147] 1.3. Preparation of positive electrode active material

[0148] Lithium transition metal composite oxides were prepared as positive electrode active materials according to the following method. These lithium transition metal composite oxides have the general formula Li 1.010 (Ni 0.621 Mn 0.224 Co 0.155 ) 0.990 O 2.00 For example, measurements obtained via ICP:

[0149] Step 1) Preparation of transition metal oxide hydroxide precursor: Nickel-based transition metal oxide hydroxide powder (TMH1) with a metal composition of Ni was prepared by co-precipitation in a large continuous stirred tank reactor (CSTR) containing a mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia. 0.621 Mn 0.224 Co 0.155 Such as measurements obtained via ICP.

[0150] Step 2) First Mixing: The TMH1 prepared in Step 1) is mixed with Li2CO3 in an industrial blender to obtain a first mixture with a lithium to metal ratio of 0.85.

[0151] Step 3) First calcination: The first mixture obtained from Step 2) is calcined at 900°C for 10 hours in a dry air atmosphere to obtain a first calcined cake. The first calcined cake is crushed to obtain a first calcined powder.

[0152] Step 4) Second Mixing: The first calcined powder obtained from Step 3) is mixed with LiOH in an industrial blender to obtain a second mixture with a lithium to metal ratio of 1.01.

[0153] Step 5) Second calcination: The second mixture from step 4) is calcined in dry air at 930°C for 10 hours, and then pulverized (bead milled) and sieved to obtain the second calcined powder.

[0154] Step 6) Third Mixing: The second calcined powder obtained from Step 5) is mixed with LiOH in an industrial blender at a total molar content of 1.5 mol% relative to Ni, Mn and Co to obtain a third mixture.

[0155] Step 7) Third calcination: The third mixture obtained from step 6) is calcined in dry air at 750°C for 10 hours to obtain the positive electrode active material.

[0156] 1.4. Preparation of positive electrode

[0157] The positive electrode is prepared according to the following procedure, comprising the positive electrode active material prepared according to Section 1.3 and the polymer electrolyte prepared according to Section 1.2:

[0158] Step 1) Prepare a polymer electrolyte solution comprising a polymer electrolyte according to Section 1.1 and a 99.8% by weight anhydrous acetonitrile solution of LiTFSI. The polymer electrolyte solution has a polymer electrolyte to LiTFSI ratio of 74:26 by weight.

[0159] Step 2) The polymer electrolyte solution prepared in Step 1), the positive electrode active material prepared according to Section 1.2, and the carbon black powder (Timcal Super carbon black) are mixed in an acetonitrile solution at a weight ratio of 21:75:4 to prepare a slurry mixture. The mixture is homogenized at 5000 rpm for 45 minutes.

[0160] Step 3) The slurry mixture obtained from Step 2) is cast onto one side of a 20 μm thick aluminum foil, wherein the coating machine slit is 100 μm.

[0161] Step 4) Dry the foil cast from the slurry at 30°C for 12 hours, and then press it to obtain a positive electrode with a diameter of 14 mm.

[0162] 1.5. Preparation of Solid Polymer Electrolytes (SPEs)

[0163] PEO-based solid polymer electrolytes (SPEs) are prepared according to the following process:

[0164] Step 1) Using a mixer at 2,000 rpm, mix polyethylene oxide (PEO, molecular weight 1,000,000) with LiTFSI (purchased from Soulbrain Co., Ltd. instead of Sigma Aldrich) in 99.8% wt% anhydrous acetonitrile for 30 minutes. The molar ratio of ethylene oxide to lithium is 20.

[0165] Step 2) Pour the mixture obtained from Step 1) into a Teflon dish and dry at 25°C for 12 hours.

[0166] Step 3) Separate the dried SPE from the dish and stamp the dried SPE to obtain an SPE disk with a thickness of 300 μm and a diameter of 19 mm.

[0167] 1.6. Polymer Battery Assembly

[0168] In an argon-filled glove box, assemble the button cell polymer battery in the following order from bottom to top: 2032 button cell casing, positive electrode prepared according to section 1.4, SPE polymer electrolyte prepared according to section 1.5, gasket, Li anode, spacer, wave spring, and battery cap. Then, completely seal the button cell to prevent electrolyte leakage.

[0169] 2. Comparative Examples

[0170] 2.1. Polymer electrolyte

[0171] Poly(ethylene oxide) (PEO) powder (Mw = 1,000,000 g / mol) purchased from Alfa Aesar was used instead of the polymer electrolyte according to the present invention.

[0172] 2.2. Preparation of positive electrode

[0173] The positive electrode is prepared according to the following procedure, comprising the positive electrode active material prepared according to Section 1.3 and the polymer electrolyte prepared according to Section 2.1:

[0174] Step 1) Prepare a polymer electrolyte solution comprising a 99.8% by weight anhydrous acetonitrile solution of the polymer electrolyte according to part 2.1 and lithium LiTFSI. The polymer electrolyte solution has a polymer electrolyte to LiTFSI ratio of 74:26 by weight.

[0175] Step 2) The polymer electrolyte solution prepared in Step 1), the positive electrode active material prepared according to Part 1.3, and the carbon black powder (Timcal Super carbon black) are mixed in an acetonitrile solution at a weight ratio of 21:75:4 to prepare a slurry mixture. The mixture is homogenized at 5000 rpm for 45 minutes.

[0176] Step 3) The slurry mixture obtained from Step 2) is cast onto one side of a 20 μm thick aluminum foil, wherein the coating machine slit is 100 μm.

[0177] Step 4) Dry the foil cast from the slurry at 30°C for 12 hours, and then press it to obtain a positive electrode with a diameter of 14 mm.

[0178] 2.3. Polymer Battery Assembly

[0179] In an argon-filled glove box, assemble the button-type polymer battery in the following order from bottom to top: 2032 button cell casing, positive electrode prepared according to Section 2.2, SPE prepared according to Section 1.5, gasket, Li anode, spacer, wave spring, and battery cap. Then, completely seal the button cell to prevent electrolyte leakage.

[0180] 3. Comparison and Testing Methods (Q) 总 )

[0181] The capacity leakage (Q) of the coin cells prepared in Chapters 2.3 and 1.6 was measured. 总 The button cell prepared in section 2.3 comprises a polymer electrolyte according to the prior art, while the button cell prepared in section 1.6 comprises a polymer electrolyte according to the invention.

[0182] Each coin cell polymer battery was cycled at 80°C using a Toscat-3100 computer-controlled constant current cycling station (from Toyo, http: / / www.toyosystem.com / image / menu3 / toscat / TOSCAT-3100.pdf). The coin cell test procedure was performed according to the following schedule, which uses a 1C current definition of 160 mA / g within a metallographic window of 4.4V / Li–3.0V / Li:

[0183] Step 1) Charge in constant current mode with a C rate of 0.05 and a termination condition of 4.4V, then let stand for 10 minutes.

[0184] Step 2) Discharge in constant current mode with a C rate of 0.05 and a termination condition of 3.0V, then let it stand for 10 minutes.

[0185] Step 3) Charge in constant current mode with a C rate of 0.05 and a termination condition of 4.4V.

[0186] Step 4) Switch to constant voltage mode and maintain 4.4V for 60 hours.

[0187] Step 5) Discharge in constant current mode with a C rate of 0.05 and a termination condition of 3.0V.

[0188] Q 总 It is defined as the total leakage capacity under high voltage and high temperature in step 4) according to the test method described above. Q 总 A low value indicates high stability of the positive electrode active material powder during high-temperature operation.

[0189] Table 2

[0190]

[0191] Table 2 summarizes the Q values ​​of polymer batteries containing positive electrodes prepared as described in Section 1.6 of Example 1 and Section 2.3 of Comparative Examples. 总 According to Table 2, it was observed that the polymer battery containing the polymer electrolyte according to the present invention (Example 1) has a significantly lower Q than the polymer battery containing the polymer electrolyte according to Example 2. 总 This demonstrates that using the polymer electrolyte according to the invention provides better electrochemical performance than using PEO as a conventional polymer electrolyte. 总 A low value indicates high stability of lithium-ion secondary batteries in applications where high voltage is applied at high temperatures.

Claims

1. A polymer electrolyte suitable for lithium-ion secondary batteries, said polymer electrolyte being obtained through a reaction between the following substances: i. At least one polymer (P), said polymer (P) being a polyether polymer, said polymer (P) comprising: a) At least 70.0 mol% of ethylene oxide units (EO); b) 0.0 mol% to 10.0 mol% of oxypropylene units (PO); and c) 1.00 mol% to 4.0 mol% of repeating units derived from at least one monomer (M) of general formula (I) or general formula (II): Equation (I) or Equation (II) in - Each of R1 and R2 is either the same as or different from each other, and is C each time it appears. 1-6 Alkyl, wherein the C 1-6 Alkyl groups are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR8 are used, wherein each R8 is the same as or different from each other and is independently selected from hydrogen and C each time it appears. 1-4 Alkyl; n is an integer, either 0, 1, or 2; - Each X is a leaving group selected from halide ions, trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate and methanesulfonate; and ii. At least one polysiloxane compound having formula (III): Equation (III) in Each of R3, R4, R5, R6, and R7 is either the same as or different from each other, and is independently selected from C each time it appears. 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 alkoxy, heterocyclic group, wherein the C 1-6 Alkyl, C 3-6 cycloalkyl, aryl, C 1-6 The alkoxy group and heterocyclic group are optionally selected from halide ions, C 1-4 Alkyl, C 3-6 One or more substituents of cycloalkyl, CF3, and OR9 are used, wherein each R9 is the same as or different from each other and is independently selected from hydrogen, C, and D in each occurrence. 1-4 Alkyl and hydroxyl protecting groups, -m is an integer of at least 3; and The at least one polysiloxane compound having formula (III) is grafted onto the at least one polymer (P) by reacting at least a portion of the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III).

2. The polymer electrolyte according to claim 1, wherein 80.0 mol% to 99.0 mol% of the repeating units of the polymer (P) are EO units.

3. The polymer electrolyte according to claim 1, wherein 90.0 mol% to 98.5 mol% of the repeating units of the polymer (P) are EO units.

4. The polymer electrolyte according to claim 1, wherein 92.0 mol% to 98.5 mol% of the repeating units of the polymer (P) are EO units.

5. The polymer electrolyte according to claim 1, wherein 94.0 mol% to 98.5 mol% of the repeating units of the polymer (P) are EO units.

6. The polymer electrolyte according to any one of claims 1 to 5, wherein 0.5 mol% to 5.0 mol% of the repeating units of the polymer (P) are PO units.

7. The polymer electrolyte according to any one of claims 1 to 5, wherein 0.5 mol% to 4.0 mol% of the repeating units of the polymer (P) are PO units.

8. The polymer electrolyte according to any one of claims 1 to 5, wherein 1.0 mol% to 4.0 mol% of the repeating unit of the polymer (P) is a PO unit.

9. The polymer electrolyte according to any one of claims 1 to 5, wherein 1.0 mol% to 3.0 mol% of the repeating unit of the polymer (P) is a PO unit.

10. The polymer electrolyte according to any one of claims 1 to 5, wherein 1.2 mol% to 4.0 mol% of the repeating units of the polymer (P) are repeating units of a monomer (M) derived from general formula (I) or general formula (II), wherein R1, R2, n and X are as defined in claim 1.

11. The polymer electrolyte according to any one of claims 1 to 5, wherein 1.5 mol% to 3.5 mol% of the repeating units of the polymer (P) are repeating units of a monomer (M) derived from general formula (I) or general formula (II), wherein R1, R2, n and X are as defined in claim 1.

12. The polymer electrolyte according to any one of claims 1 to 5, wherein 1.5 mol% to 3.0 mol% of the repeating units of the polymer (P) are repeating units of a monomer (M) derived from general formula (I) or general formula (II), wherein R1, R2, n and X are as defined in claim 1.

13. The polymer electrolyte according to any one of claims 1 to 5, wherein the monomer (M) has formula (II). Equation (II) in - Each of R1 and R2 is either the same as or different from each other, and is C each time it appears. 1-2 Alkyl, and n is an integer 0 or 1.

14. The polymer electrolyte according to claim 13, wherein n is 1.

15. The polymer electrolyte according to any one of claims 1 to 5, wherein the polymer (P) is a random copolymer having a number-average molecular weight Mn of at least 10,000 g / mol and at most 150,000 g / mol.

16. The polymer electrolyte according to any one of claims 1 to 5, wherein each of R3, R4, and R7 is the same as or different from each other and independently constitutes C each time it appears. 1-6 Alkyl; each of R5 and R6 may be the same as or different from each other and is independently selected from C1 each time it appears. 1-4 alkyl or phenyl, wherein the C 1-4 Alkyl groups are optionally selected from halide ions, C 1-4 One or more substituents of alkyl or CF3 are used; m is an integer of at least 5 and at most 1000.

17. The polymer electrolyte of claim 16, wherein m is an integer of at least 5 and at most 500.

18. The polymer electrolyte of claim 16, wherein m is an integer of at least 5 and at most 100.

19. The polymer electrolyte of claim 16, wherein m is an integer of at least 5 and at most 20.

20. The polymer electrolyte of claim 16, wherein m is an integer of at least 7 and at most 20.

21. The polymer electrolyte of claim 16, wherein m is an integer of at least 8 and at most 15.

22. The polymer electrolyte according to any one of claims 1 to 5, wherein the polymer (P) and the polysiloxane having formula (III) are at least partially dissolved in an organic solvent selected from benzene, toluene, xylene and methylisopropylbenzene.

23. The polymer electrolyte according to any one of claims 1 to 5, wherein the polysiloxane compound having formula (III) is grafted onto the polymer (P) in the presence of a catalyst.

24. The polymer electrolyte according to any one of claims 1 to 5, wherein the polysiloxane compound having formula (III) is grafted onto the polymer (P) in the presence of a hydrosilylation catalyst selected from Karstedt catalyst, Wilkinson catalyst, Speier catalyst or mixtures thereof.

25. The polymer electrolyte according to any one of claims 1 to 5, wherein the polysiloxane compound having formula (III) is grafted onto the polymer (P) by reacting at least 10 mol% and at most 90 mol% of the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III).

26. The polymer electrolyte according to any one of claims 1 to 5, wherein the polysiloxane compound having formula (III) is grafted onto the polymer (P) by reacting at least 30 mol% and at most 70 mol% of the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III).

27. The polymer electrolyte according to any one of claims 1 to 5, wherein the polysiloxane compound having formula (III) is grafted onto the polymer (P) by reacting at least 40 mol% and at most 60 mol% of the -CH=CH2 portion of the monomer (M) with the H-Si portion of the polysiloxane compound having formula (III).

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