Polymer electrolyte and method for manufacturing the same

Abstract

To provide a polymer electrolyte having high ion conductivity, a method for manufacturing the same, and a battery.SOLUTION: A polymer electrolyte for a battery is provided, including: (i) a first polymaleimide polymer including a first polymaleimide repeating unit, wherein the first polymaleimide repeating units is according to R3(Q)μ, wherein R3 is individually polyether or C(H)h(CxH2x+1)i((CH2)ψ)j(CH2OC(O)(CH2)σ)k, wherein i is 0-2, j and k are individually 0-4, h is 4-i-j-k, h+i is 0-2, x is 1-6, ψ is 1-10, σ is 1-20, μ is individually at least 2, and Q is individually the formula (I); and a specific second polymaleimide polymer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polymer electrolytes, particularly solid state electrolytes. The present invention further relates to batteries containing polymer electrolytes, and to methods for manufacturing polymer electrolytes.

Background Art

[0002] The importance of batteries and other energy storage devices is increasing rapidly. The rise of e-mobility, particularly electric vehicles and e-scooters, requires high-capacity and reasonably-weighted batteries.

[0003] Current research in battery technology focuses on developing new materials to improve battery safety, increase and optimize volumetric and gravimetric energy densities.

[0004] Conventional liquid electrolytes, such as those used in lithium batteries, are based on mixtures of organic solvents and lithium salts. These electrolytes have high ionic conductivity and are electrochemically stable within the battery's voltage window. However, such liquid electrolytes are highly flammable, volatile, and can leak outside the battery casing. These drawbacks can lead to significant battery drawbacks, such as ignition and explosion.

[0005] In recent years, solid electrolytes, polymer electrolytes (such as gel (polymer) electrolytes), and ionic liquid electrolytes have been developed to improve the safety of alkali metal batteries and alkaline earth metal batteries.

[0006] A gel polymer electrolyte is a system in which a liquid electrolyte is encapsulated and impregnated in a cross-linked, typically chemically cross-linked polymer structure. This type of electrolyte provides a relatively high ionic conductivity at a reasonable price and also has high structural, thermal, and mechanical stability over time. However, the ionic conductivity is still lower than that of liquid electrolytes because the cross-linked polymer structure tends to impede the movement of metal ions, for example, lithium ions in a lithium-ion battery.

[0007] International Publication No. 2022 / 055307 discloses a gel polymer electrolyte for a lithium secondary battery obtained from a precursor composition containing two cross-linking agents, one of which is a cross-linking agent containing at least two thiol functional groups, a lithium salt, and a small amount of an organic solvent.

[0008] U.S. Patent Application Publication No. 2023096123 discloses a solid polymer electrolyte including a cross-linked polymer network. The cross-linked polymer network includes a cross-linking group, such as a difunctional polyether group and / or a difunctional ionic group, and at least one cross-linking group including a cross-linking polyfunctional cross-linking group and a thioether group. For the solid polymer electrolyte to be conductive, it must further include a double-ion conducting salt (such as a metal salt), a tethered ionic group, and / or a liquid electrolyte.

[0009] A disadvantage of the aforementioned electrolytes is that the polyether group is unstable at high voltages (e.g., 4V or higher). A further disadvantage is that there is a risk of polarization in a battery containing these electrolytes, which is due to the use of a double-ion conducting salt and the low lithium transference number of the electrolyte. As is known, polarization reduces the power density of the battery, thereby limiting the current value that can be used for charging and discharging the battery. In other words, polarization in the battery results in a battery having a performance that rapidly decreases with each charge and discharge cycle. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to overcome one or more of the aforementioned drawbacks. The object of the present invention is to provide a polymer electrolyte having high ionic conductivity, particularly lithium ion conductivity. A further object is to provide a polymer electrolyte having high structural, electrochemical, thermal and mechanical stability over time. A further object is to provide a polymer electrolyte that is substantially free of any processing solvents. A further object is to provide a polymer electrolyte for a battery that reduces the risk of polarization in the battery and thereby improves the current value that can be used in the battery, and in particular provides a battery having high performance and a longer life (i.e., the reduction in performance is significantly reduced or further avoided) during repeated charge / discharge cycles.

[0011] A further object is to provide a method for producing such a polymer electrolyte having high ionic conductivity, high voltage stability up to at least 4 V, and thermal and mechanical stability.

[0012] According to a first aspect of the present disclosure, there is provided a polymer electrolyte for a battery as set forth in the appended claims. The polymer electrolyte comprises or consists essentially of a first polymaleimide polymer and a second polymaleimide polymer. The first polymaleimide polymer comprises or consists essentially of first polymaleimide repeat units. The second polymaleimide polymer comprises or consists essentially of second polymaleimide repeat units.

[0013] The first polymaleimide repeat unit is R 3 (Q) μ wherein μ is individually at least 2, preferably from 2 to 4. Q is individually of formula (I):

Chemical formula

[0014] Preferably, R 2 is methyl, ethyl, propyl, n-butyl, isobutyl, benzyl or styryl.

[0015] Preferably, R 4 is H, methyl, ethyl or propyl.

[0016] R 3 is, individually, C(H) h (C x H 2x+1 ) i ((CH2) ψ ) j (CH2OC(O)(CH2) σ ) k or a polymer, where i is 0-2; j and k are, individually, 0-4; h is 4-i-j-k; the sum of h and i is 0-2; x is 1-6; ψ is 1-10; σ is 1-20.

[0017] Preferably, when R 3 is a polyether, the polyether is -(CH2) ω (O(CH2) sigma ) α -, where ω is 0-4, sigma is 1-4, and α is 1-10, preferably 1-5.

[0018] Alternatively, more preferably, R 3 is -(CH2) β- and wherein β is from 1 to 20 (i.e., h is 2, i is 0, j is 2, k is 0). Additionally or alternatively and preferably, R 3 is C(CH2CH3)(CH2OC(O)(CH2) σ )3- (i.e., h is 0, i is 1, j is 0, k is 3). Additionally or alternatively and preferably, R 3 is C(CH2OC(O)(CH2) σ )4- (i.e., h is 0, i is 0, j is 0, k is 4).

[0019] The second polymaleimide repeating unit is of formula (II):

Chemical formula

[0020] Preferably, R 1 is H, methyl, ethyl or propyl.

[0021] Preferably, X is CF3, CH3 or F.

[0022] Preferably, the alkali metal is lithium, sodium or potassium, preferably lithium. In other words, the alkali metal ion is preferably a lithium ion (Li + ), a sodium ion (Na + ), or a potassium ion (K + ), preferably a lithium ion.

[0023] Preferably, the molar ratio of the first polymaleimide polymer to the second polymaleimide polymer is 5 to 95, preferably 10 to 75, more preferably 20 to 50, based on the total moles of each polymer in the polymer electrolyte. The inventors have found that when the molar ratio of the first polymaleimide polymer to the second polymaleimide polymer is 5 to 95, the polymer electrolyte has excellent ionic conductivity in combination with optimal mechanical properties.

[0024] The polymer electrolyte may further contain a plasticizer. Preferably, the polymer electrolyte contains 0 wt% to 90 wt%, preferably 0 wt% to 80 wt% of the plasticizer, based on the total weight of the polymer electrolyte. Preferably, when the polymer electrolyte contains a plasticizer, it contains 0.5 wt% to 90 wt%, such as 5 wt% to 85 wt%, preferably 10 wt% to 85 wt%, such as 20 wt% to 80 wt%, more preferably 45 wt% to 60 wt% of the plasticizer, based on the total weight of the polymer electrolyte.

[0025] Preferably, the plasticizer is selected from the group consisting of linear carbonates, cyclic carbonates, ethers, and nitriles. Preferably, the plasticizer is a linear carbonate or a cyclic carbonate. Particularly preferred examples of the plasticizer are propylene carbonate and ethylene carbonate. The polymer electrolyte may contain two or more plasticizers, which are each individually selected from the group consisting of linear carbonates, cyclic carbonates, ethers, and nitriles.

[0026] According to a second aspect of the present disclosure, a battery as set forth in the appended claims is provided.

[0027] The battery includes the polymer electrolyte of the first aspect of the present disclosure. Preferably, the battery is a secondary battery. Preferably, the battery is a lithium metal battery.

[0028] According to a third aspect of the present disclosure, a method for manufacturing a polymer electrolyte for a battery as set forth in the appended claims is provided. The polymer electrolyte comprises, or consists essentially of, a first polymaleimide polymer and a second polymaleimide polymer. Preferably, the polymer electrolyte manufactured by the method of the third aspect of the present disclosure is the polymer electrolyte of the first aspect of the present disclosure.

[0029] The method includes the step of preparing a compound comprising, or consisting essentially of, a third polymaleimide polymer comprising third polymaleimide repeating units, a second polymaleimide polymer comprising second polymaleimide repeating units, a free radical initiator, and a thiol-ene reagent.

[0030] The third polymaleimide repeating unit is of formula (III):

Chemical formula

[0031] The second polymaleimide repeating unit is according to formula (II).

[0032] The thiol-ene reagent contains a thiol group. The number of thiol groups, q, is at least 2, for example 2, 3, 4 or more.

[0033] In the present disclosure, "thiol group" means the functional group -SH, that is, a sulfur atom covalently bonded to a hydrogen atom.

[0034] The number of third polymaleimide repeating units, n, the number of thiol groups, q, and the number of thiol-ene reagent molecules, a, are

Number

Number

Number

[0035] Optionally, the compound further includes a processing solvent. The term "processing solvent" is used in the present disclosure with respect to a solvent that is used during the production of the polymer electrolyte but does not exist in the polymer electrolyte. Preferably, the optional processing solvent includes, or consists essentially of, acetone, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, or a combination of two or more thereof.

[0036] The inventors have surprisingly found that the compound enables its handling, for example, application to a substrate, and obtains favorable viscosity and handling properties without the need for a processing solvent, thereby surprisingly making the presence of the processing solvent in the compound optional.

[0037] Optionally, the compound further includes a plasticizer. The optional plasticizer is as described above. Preferably, the compound includes 0.5 wt% to 90 wt%, for example 5 wt% to 85 wt%, 10 wt% to 85 wt%, preferably 20 wt% to 80 wt%, for example 45 wt% to 60 wt% of the plasticizer based on the total weight of the compound minus the weight of the optional processing solvent.

[0038] In the present disclosure, the term "total weight of the compound minus the weight of the optional processing solvent" is used with respect to the weight of the compound when the compound does not include the processing solvent, and the weight of the compound without considering the weight of the processing solvent when the compound includes the processing solvent.

[0039] Preferably, the free radical initiator is capable of initiating a thiol-ene reaction between the third poly(maleimide) repeat unit and the thiol-ene reagent. Preferably, upon initiation, a sulfur-carbon covalent bond is formed between the third poly(maleimide) repeat unit and the thiol-ene reagent, leading to a thio-ether linkage.

[0040] Preferably, the compound contains 0.05 wt% to 1.5 wt%, preferably 0.075 wt% to 1.4%, more preferably 0.1 wt% to 1.25% of the free radical initiator, based on the total weight of the compound minus the weight of any optional processing solvent.

[0041] Preferably, the compound contains 0 wt% to 95 wt%, such as 1 wt% to 95 wt%, 5 wt% to 92.5 wt%, preferably 10 wt% to 90 wt%, more preferably 20 wt% to 90 wt%, such as 50 wt% to 90 wt% of the processing solvent, based on the total weight of the compound including the weight of the processing solvent.

[0042] In the present disclosure, the term "total weight of the compound including the weight of the processing solvent" is used with respect to the weight of the compound when the compound does not contain the processing solvent (processing solvent in the compound is 0 wt%), and the weight of all components of the compound including the processing solvent when the compound contains the processing solvent.

[0043] Preferably, the compound contains 3 wt% to 45 wt%, preferably 10 wt% to 40% in total of the third poly(maleimide) polymer and the thiol-ene reagent, based on the total weight of the compound minus the weight of any optional processing solvent.

[0044] Preferably, the compound contains 5 wt% to 95 wt%, preferably 40 wt% to 90% of the second poly(maleimide) polymer, based on the total weight of the compound minus the weight of any optional processing solvent.

[0045] Preferably, when the compound contains a plasticizer, the compound contains 30 wt% to 80 wt% plasticizer, 3 wt% to 45 wt% combined third polymaleimide polymer and thiol-ene reactant, and 0.05 wt% to 1.5 wt% free radical initiator, based on the total weight of the compound minus the weight of any optional processing solvent.

[0046] More preferably, when the compound contains a plasticizer, the compound contains 45 wt% to 75 wt% plasticizer, 5 wt% to 40 wt% combined third polymaleimide polymer and thiol-ene reactant, 2 wt% to 40 wt% second polymaleimide polymer, and 0.1 wt% to 1.25 wt% free radical initiator, based on the total weight of the compound minus the weight of any optional processing solvent.

[0047] The method further includes applying the compound to a substrate. The substrate may be any substrate, such as a Teflon sheet or glass, or may be an anode or cathode of a battery. The application of the compound to the substrate may be by means known in the art, such as, without limitation, casting, hot pressing or cold pressing, pressing which may or may not involve the application of any pressure, such as by spatula. Preferably, a film of the compound is obtained upon application of the compound to the substrate.

[0048] When the compound contains a processing solvent, the method further includes its removal, whereby a substantially processing solvent-free compound is obtained.

[0049] The method further includes exposing a compound (substantially free of processing solvent) to one or more of UV irradiation, IR irradiation, or a temperature up to 100°C. When exposed to one or more of UV irradiation, IR irradiation, or a temperature up to 100°C, the thiol-ene reaction of the compound (substantially free of processing solvent), particularly of the thiol-ene reactant and the third poly(maleimide) repeat unit, is initiated, thereby obtaining a polymer electrolyte containing thio-ether linkages, i.e., sulfur-carbon covalent bonds.

[0050] Preferably, the thiol-ene reaction enables crosslinking of the compound, particularly of the third poly(maleimide) repeat unit, thereby obtaining a polymer electrolyte containing thio-ether linkages. In particular, a film or sheet of the polymer electrolyte is obtained on a substrate.

[0051] Advantages of the method of the present invention include the possibility of reducing or eliminating the use of processing solvents, which makes the method more environmentally friendly.

[0052] Advantages of the presence of the second poly(maleimide) repeat unit and an optional plasticizer in the polymer electrolyte of the present disclosure include high ionic conductivity and high stability over time. Advantages of the presence of the first poly(maleimide) repeat unit in the polymer electrolyte of the present disclosure include high thermal, structural, and mechanical stability over time. Generally, an advantage of the polymer electrolyte of the present disclosure is the ability to resist high voltages, which enables use in combination with active materials to operate at high voltages.

[0053] Advantages of the battery of the present invention, i.e., a battery containing the polymer electrolyte of the present invention, include high ionic conductivity and excellent resistance to repeated charge / discharge, thereby having an excellent lifespan.

Brief Description of the Drawings

[0054] Aspects of the present invention will now be described in more detail with reference to the accompanying figures, in which like reference numerals exemplify like features.

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4A-4B

Figure 5A-5B

Figure 6

Figure 7

Figure 8A-8C

Figure 9A-9C

Figure 10

Figure 11A-11B

Figure 12A-12B

Figure 13A-13B

DETAILED DESCRIPTION OF THE INVENTION

[0055] The polymer electrolyte comprises, or consists essentially of, a first polymaleimide polymer, a second polymaleimide polymer, and optionally a plasticizer. The first polymaleimide polymer preferably comprises, or consists essentially of, first polymaleimide repeating units. The second polymaleimide polymer preferably comprises, or consists essentially of, second polymaleimide repeating units.

[0056] The first polymaleimide repeating unit is by R 3 (Q) μ by.

[0057] μ is individually at least 2, preferably 2 to 4.

[0058] Q is individually of formula (I):

Chemical formula

[0059] Preferably, R 2 is individually C1 - C 16 alkyl, preferably C1 - C 10Alkyl, more preferably C1-C8 alkyl, most preferably C1-C6 alkyl, such as methyl, ethyl, propyl and butyl. R 2 may be linear or branched.

[0060] Alternatively or further, more preferably, R 2 is, individually, C2-C 16 alkenyl containing one or more C=C bonds, preferably C2-C 10 alkenyl, more preferably C2-C8 alkenyl, most preferably C2-C6 alkenyl. R 2 may be linear or branched.

[0061] Alternatively or further, more preferably, R 2 is, individually, C2-C 16 alkynyl containing one or more C≡C bonds, preferably C2-C 10 alkynyl, more preferably C2-C8 alkynyl, most preferably C2-C6 alkynyl. R 2 may be linear or branched.

[0062] Alternatively or further, more preferably, R 2 is, individually, aryl, such as benzyl or phenyl.

[0063] Preferably, R 4 is H, C1-C 16 alkyl, C2-C 16 alkenyl or C2-C 16 alkynyl, preferably H, C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl, most preferably H, C1-C4 alkyl, C2-C4 alkenyl or C2-C4 alkynyl. Alkyl, alkenyl and alkynyl may each be linear or branched.

[0064] Preferred examples of Q are

Chemical formula

[0065] Preferably, Q is covalently bonded to R 3 through the sulfur atom of Q.

[0066] Preferably, each R 3 is, individually, a polyether. By "individually" is meant that the first poly(maleimide) repeating unit can be different from each other, for example, by containing different R 3 . Preferably, each R 3 is -(CH2) ω (O(CH2) sigma ) α - where ω is from 0 to 6, preferably from 0 to 4, more preferably from 1 to 4, sigma is from 1 to 4, preferably from 1 to 3, for example 2, and α is from 1 to 10, preferably from 1 to 5, more preferably from 2 to 4.

[0067] 3 For example, R α is -(CH2)2(O(CH2)2) 3 - (i.e., ω is 2 and sigma is 2), for example -(CH2)2(O(CH2)2)2- (i.e., α is 2) or -(CH2)2(O(CH2)2)3- (i.e., α is 3).

[0068] Alternatively or additionally, still preferably, each R h is, individually, C(H)(C x H 2x+1 ) i ((CH2) ψ ) j (CH2OC(O)(CH2) σ ) kIt is based on. Preferably, x is 1 to 6, preferably 1 to 4, more preferably 1 or 2. Preferably, ψ is 1 to 10, preferably 1 to 8, more preferably 1 to 6, for example 1 to 4. Preferably, σ is 1 to 20, preferably 1 to 10, for example 1 to 6, more preferably 1 to 4. Further, i is 0 to 2, and j and k are, individually, 0 to 4. Further, h is 4 - i - j - k. The sum of h and i is 0 to 2.

[0069] For example, R 3 is -(CH2) β where β is 1 to 20 (that is, h is 2, i is 0, j is 2, k is 0, and β is equal to 2*ψ + 1).

[0070] For example, R 3 is C(C2H5)(CH2OC(O)(CH2) σ )3- (that is, h is 0, i is 1, j is 0, k is 3, and x is 2).

[0071] For example, R 3 is C(CH2OC(O)(CH2) σ )4- (that is, h is 0, i is 0, j is 0, k is 4, and x is 2).

[0072] The second polymaleimide unit is of the formula (II):

Chemical formula

[0073] Preferably, R 1 is H, C1 - C 16 alkyl, C2 - C 16 alkenyl or C2 - C 16 alkynyl, preferably H, C1 - C6 alkyl, C2 - C6 alkenyl or C2 - C6 alkynyl, more preferably H, C1 - C4 alkyl, C2 - C4 alkenyl or C2 - C4 alkynyl. Alkyl, alkenyl and alkynyl may each be straight-chain or branched-chain.

[0074] Preferably, X is H, F, C1-C 16 alkyl, C1-C 16 fluoroalkyl, preferably H, F, C1-C6 alkyl or C1-C6 fluoroalkyl, more preferably H, F, CH3 or CF3. The alkyl and fluoroalkyl may be linear or branched.

[0075] Preferably, M + is independently an alkali metal ion. Preferably, the alkali metal is lithium, sodium or potassium. In other words, the alkali metal ion is preferably a lithium ion (Li + ), a sodium ion (Na + ), or a potassium ion (K + ).

[0076] Preferably, m is from 1 to 5.

[0077] A preferred example of the second polymerized maleimide repeating unit is of formula IV:

Chemical formula

[0078] A non-limiting example of the first polymerized maleimide polymer is shown in formula V.

Chemical formula

[0079] Yet another non-limiting example of a polymer electrolyte is shown in Formula VI.

Chemical formula

[0080] Yet another non-limiting example of a polymer electrolyte is shown in Formula VII.

Chemical formula

[0081] The polymer electrolyte may further comprise a polyimide copolymer comprising, or consisting essentially of, first and second polyimide repeating units covalently bonded to each other, preferably by carbon-carbon bonds.

[0082] Preferably, the polymer electrolyte is thermally stable up to at least 75 °C, preferably up to at least 100 °C, or at least up to 125 °C.

[0083] Preferably, the polymer electrolyte has an ionic conductivity of at least 0.25 mS / cm, preferably at least 0.3 mS / cm, more preferably at least 0.4 mS / cm at 70 °C.

[0084] Preferably, the polymer electrolyte has an oxidation stability of at least 3 V, preferably at least 4 V at 70 °C.

[0085] Preferably, the polymer electrolyte of the present invention is self-supporting. The terms "self-supporting" and "self-supporting" are used interchangeably and refer to a film, substrate, product or article that has sufficient mechanical strength to be manipulated, e.g., cut, shaped or handled, without the need for a carrier or support on which the film is placed to avoid damage to the film.

[0086] The polymer electrolyte of the present disclosure is preferably produced (i.e., produced or prepared) by the method of the present disclosure.

[0087] In a first step, a compound is prepared. The compound comprises a third polymaleimide polymer comprising a third polymaleimide repeating unit, a second polymaleimide polymer comprising a second polymaleimide repeating unit, a thiol-ene reagent and a free radical initiator.

[0088] Optionally, the compound further comprises a plasticizer. Optionally, the compound further comprises a processing solvent.

[0089] The third polymaleimide repeating unit has a pendant vinyl group and is of formula III:

Chemical formula

[0090] Preferably, the number, n, of the third polyimide repeating units contained in the third polyimide polymer is from 10 to 10,000, preferably from 100 to 7,500, more preferably from 500 to 4,000.

[0091] Preferably, the average number molecular weight of the third polyimide polymer is from 1 kDa to 1,500 kDa, preferably from 15 kDa to 1,000 kDa, more preferably from 75 kDa to 800 kDa.

[0092] The second polyimide repeating unit is according to Formula II. Preferably, the number, p, of the second polyimide repeating units contained in the second polyimide polymer is from 10 to 10,000, preferably from 100 to 7,500, more preferably from 500 to 4,000.

[0093] Preferably, the number average molecular weight of the second polyimide polymer is from 3 kDa to 2,000 kDa, preferably from 100 kDa to 1,750 kDa, more preferably from 250 kDa to 1,500 kDa.

[0094] A first example of the third polyimide polymer is Formula VIII:

Chemical formula

[0095] A second example of the third polyimide polymer is Formula IX:

Chemical formula

[0096] An example of a second polymaleimide polymer is of formula XIV: [Chemical formula] (wherein R 1 is as described above herein, for example H, m is 2, M + is Li + (lithium ion), and X is CF3).

[0097] The thiol-ene reactant contains a thiol group. The number of thiol groups, q, is at least 2, for example 2, 3, 4 or more. Preferably, the thiol-ene reactant is R 3 (SH) μ , where R 3 and μ are as described above herein.

[0098] Non-limiting examples of the thiol-ene reactant include, without limitation, formula X (q = 2), XI (q = 2), XII (q = 3) and XIII (q = 4): [Chemical formula] (wherein α is from 1 to 10, preferably from 1 to 5, more preferably from 2 to 4, for example 2, 3 or 4); [Chemical formula] (wherein β is from 1 to 20, preferably from 2 to 18, more preferably from 5 to 15, for example from 8 to 12, for example 10); [Chemical formula] (wherein γ, δ and ε are each, independently, from 0 to 19, preferably from 0 to 10, more preferably from 0 to 4); and, [Chemical formula] (wherein η, θ, λ, and ξ are each, independently, from 0 to 19, preferably from 0 to 10, more preferably from 0 to 4) including compounds according to.

[0099] A preferred example of the free radical initiator is 2-hydroxy-2-methylpropiophenone.

[0100] The inventors have found that the presence of a processing solvent in the compound is optional. The advantages of the processing solvent being optional are a reduction in the cost of the compound and the polymer electrolyte, the process for manufacturing the polymer electrolyte becoming less complex (i.e., having fewer processing steps), the need for additional (processing) solvent recovery being eliminated, and a reduction in the environmental impact.

[0101] However, depending on the exact composition of the compound, a processing solvent may be added and its properties optimized in view of the conversion to the polymer electrolyte. Whether to add a processing solvent to the compound thus depends on the type and amount of the third and second polymaleimide repeating units, the thiol-ene reactant, the free radical initiator, and the optional plasticizer.

[0102] When the compound contains a processing solvent, the latter preferably comprises or consists essentially of acetone, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, or a combination of two or more thereof.

[0103] When the compound contains a plasticizer (i.e., a plasticizing agent), the plasticizer is preferably selected from the group consisting of linear carbonates, cyclic carbonates, ethers, and nitriles. Particularly preferred examples of the plasticizer are propylene carbonate and ethylene carbonate. The compound may contain two or more plasticizers, which are individually selected from the group consisting of linear carbonates, cyclic carbonates, ethers, and nitriles.

[0104] Optionally, the compound further includes a crosslinking agent. Non-limiting examples of crosslinking agents include polyethylene glycol diacrylate (PEGDA), trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETA), and butyl acrylate (BA).

[0105] Optionally, the compound further includes a metal salt. Preferably, when the compound includes a metal salt, the metal is preferably lithium, sodium, magnesium, or aluminum.

[0106] Preferably, the compound includes 0 wt% to 10 wt%, such as 0.1 wt% to 7.5 wt%, preferably 0.2 wt% to 5 wt%, more preferably 0.5 wt% to 5 wt% of the metal salt, based on the total weight of the compound minus the weight of any optional processing solvent.

[0107] Preferably, the compound is applied to a substrate, thereby obtaining a film of the compound. Preferably, the film has a thickness of 10 μm to 1000 μm, preferably 20 μm to 750 μm, more preferably 25 μm to 500 μm, such as 50 μm to 250 μm. It is understood that the thickness can vary based on the targeted or required thickness of the polymer electrolyte. Preferably, the targeted or required thickness is determined based on the required total cell resistance and required mechanical properties, such as mechanical strength and flexibility.

[0108] Preferably, when the compound includes a processing solvent, the processing solvent is removed after the compound is applied to the substrate and before the compound (substantially free of the processing solvent) is exposed to one or more of UV irradiation, IR irradiation, or a temperature up to 100 °C.

[0109] Preferably, the processing solvent is removed by heating the substrate containing the compound to a temperature of 20 °C to 100 °C, preferably 20 °C to 50 °C.

[0110] Preferably, when the compound contains a plasticizer, the substrate is heated to a temperature below the maximum continuous use temperature of the plasticizer as defined by the Underwriter Laboratory (UL 746B) relative thermal index (RTI), preferably 20 °C to T v - 10 °C (where T v is the maximum continuous use temperature of the plasticizer defined by the Underwriter Laboratory (UL 746B) relative thermal index (RTI)). By doing so, evaporation and / or removal of the plasticizer will be avoided.

[0111] Alternatively or additionally and preferably, the processing solvent is removed by exposing the substrate containing the compound to an atmosphere at a pressure below atmospheric pressure.

[0112] Preferably, when a pressure below atmospheric pressure is applied, the pressure is 975 mbar or less, preferably 950 mbar or less, more preferably 930 mbar or less, for example 900 mbar or less, 750 mbar or less, or 500 mbar or less.

[0113] It will be understood that the optimum temperature and / or pressure for evaporating the processing solvent depends on the composition of the compound. In particular, when the compound contains a plasticizer, the optimum conditions for evaporating the processing solvent depend on the plasticizer used, and the conditions are preferably selected to avoid evaporation or decomposition of the plasticizer.

[0114] Preferably, the processing solvent is acetone. Acetone is particularly preferred because it has a relatively low boiling point (i.e., 56 °C at atmospheric pressure) and a relatively high vapor pressure (i.e., 230 mm Hg at 25 °C). This boiling point and vapor pressure allow for the removal of the processing solvent by heating to a moderate temperature, for example about 40 °C to 65 °C at atmospheric pressure, preferably at atmospheric pressure, and / or at a pressure slightly below atmospheric pressure, for example about 950 mbar, at 50 °C to 60 °C.

[0115] Preferably, exposure of the compound (substantially free of processing solvent) to one or more of UV irradiation, IR irradiation or temperatures up to 100 °C initiates the thiol-ene reaction of the thiol-ene reagent and the third polymaleimide repeating unit, thereby obtaining a first polymaleimide polymer comprising or consisting essentially of the first polymaleimide repeating units according to formula I.

[0116] In other words, when exposed to one or more of UV irradiation, IR irradiation or temperatures up to 100 °C, the compound (substantially free of processing solvent) is converted into a polymer electrolyte, in particular the first and second polymaleimide polymers described above herein, namely the first polymaleimide polymer comprising the first polymaleimide repeating units of formula I and the second polymaleimide polymer comprising the second polymaleimide repeating units of formula II, of the polymer electrolyte of the present disclosure.

Examples

[0117] Example 1 Nine compounds were prepared that contained the same components but in different amounts. Table 1 shows the weight % of each component for all nine compounds. For all compounds,

Number

[0118] The compound comprised a third polymaleimide polymer comprising third polymaleimide repeating units according to formula III, where R 2 is CH2 and R 4 is H. The third polymaleimide polymer ("third" in Table 1) had a number average molecular weight of 100 kDa to 650 kDa.

[0119] The compound comprises a second polymaleimide polymer (the "second" in Table 1) containing a second polymaleimide repeating unit described by Formula II, where R 1 is H, m is 2, M + is Li + and X is CF3, and the number average molecular weight was 250 kDa to 1500 kDa.

[0120] The thiol-ene reagent (the "2SH" in Table 1) contains two thiol groups and follows Formula X, where α is 2 and the molecular weight is 182 Da.

[0121] The plasticizer (the "PC" in Table 1) is propylene carbonate having a molecular weight of 102 Da, and the free radical initiator (the "Ini" in Table 1) is 2-hydroxy-2-methylpropiophenone having a molecular weight of 164 Da. Table 1: Compound composition expressed in weight % based on the total weight of the compound minus the weight of acetone as the solvent

Table 1

[0122] Acetone as a processing solvent was added to the nine compounds in Table 1 in an amount such that the compound contained 86 wt% acetone based on the total weight of the compound including the weight of acetone. The compound containing acetone was then applied to a Teflon substrate by casting, more specifically solvent casting.

[0123] The Teflon substrate containing the compound was placed in an argon box, and acetone was removed by supplying an argon stream to the substrate at room temperature and atmospheric pressure for 24 hours.

[0124] Next, the substantially solvent-free compound was exposed to UV irradiation, thereby stimulating the thiol-ene reaction, which led to a polymer electrolyte film having a thickness of 150-200 μm. The films were free-standing. In other words, they had sufficient mechanical strength to be manipulated without further requiring a Teflon substrate as a support material (see Figure 1).

[0125] Four reference polymer electrolytes were also prepared.

[0126] A first reference electrolyte was prepared from a compound containing a second polymaleimide polymer and a plasticizer of nine of the compounds of the present invention, and polyethylene glycol diacrylate (PEGDA, number average molecular weight 700 g / mol) as a crosslinking agent, and polyvinylidene difluoride-hexafluoropropylene copolymer (PVdF-HFP) as a mechanical support. The reference compound was then polymerized by radical polymerization. The resulting polymer electrolyte contained 7.3 wt% of the second polymaleimide polymer, 5 wt% of the PVdF-HFP copolymer, 17.6 wt% of PEGDA, and 70.1 wt% of the plasticizer, based on the total weight of the electrolyte.

[0127] Three further reference electrolytes contained a second polymaleimide polymer and polyethylene glycol dimethyl ether, Mw 500 (PEGDME) as a plasticizer in 5M polyethylene oxide (PEO) powder in acetonitrile solution. All three had a ratio of 20 ethylene oxide units to lithium ion, and weight ratios of PEO to PEGDME of 20 / 80, 30 / 70 and 40 / 60, respectively.

[0128] Example 2 The ionic conductivities of the nine polymer electrolytes described in the present invention, as well as four reference polymer electrolytes (all as prepared in Example 1) and 100% polyethylene oxide (PEO) as a benchmark, were measured by alternating current (AC) impedance spectroscopy using a BT Laboratories potentiostat (Bio-Logic Science Instruments). Measurements were carried out at temperatures varying from 25 °C to 70 °C in the frequency range from 10 kHz to 0.1 Hz. Ionic conductivity is a measure of the suitability of the polymer electrolyte to be used in a battery.

[0129] Figure 2A shows an Arrhenius plot of the ionic conductivity (S / cm) for the nine polymer electrolytes of the present invention. Figure 2B shows an Arrhenius plot of the ionic conductivity for the first reference electrolyte. Figure 2C shows Arrhenius plots of the ionic conductivity for the second to fourth reference electrolytes (samples 20 / 80, 30 / 70 and 40 / 60), together with the PEO benchmark (sample 100 / 0), respectively.

[0130] From Figures 2B and 2C, it is clear that all four reference electrolytes show reasonable or excellent ionic conductivity values, while the values for the 100% PEO sample are very low and below acceptable values, as expected. The ionic conductivity values of the four reference electrolytes were diverse, being 2 × 10 -7 S / cm to 1.5 × 10 -5 S / cm at 25 °C and 2 × 10 -5 S / cm to 4 × 10 -5 S / cm at 70 °C.

[0131] All nine electrolytes of the present invention (Figure 2A) showed high ionic conductivities, which were several orders of magnitude higher than those of the reference electrolytes at that temperature at all temperatures. The ionic conductivity values of the electrolytes of the present invention were 1.5 × 10 -5 S / cm to 10 -4 S / cm at 25 °C and 6 × 10 -5 S / cm to 4 × 10 -4It varied in S / cm. It was noted that higher ionic conductivity was measured for samples with a smaller amount of the first polymaleimide polymer. A smaller amount of the first polymaleimide polymer means a larger amount of lithium cations in the electrolyte, which could explain the higher ionic conductivity.

[0132] Example 3 For the polymer electrolytes obtained from Compound Nos. 2, 3, and 5 in Table 1 and Example 1, and for four reference polymer electrolytes, lithium transference number and lithium conductivity were measured. The Li transference number was measured by a combined measurement of AC impedance and DC polarization method described in “Electrochemical measurement of transference numbers in polymer electrolytes”, Evans et al., Polymer Volume 28, Issue 13 (1987), 2324 - 2328. A lithium symmetric cell with a polymer electrolyte as the electrolyte was used for this purpose. The temperature of the cell was controlled by a temperature chamber at 70 °C. The lithium transference number was calculated by Equation 1.

Equation

[0133] The Li conductivity was calculated by multiplying the total ionic conductivity of the electrolyte by the lithium transference number. The lithium transference number is defined as the ratio of the current derived from lithium cations in the polymer electrolyte to the total current. When the lithium transference number is close to 1, it indicates that the ionic conduction performance in the polymer electrolyte is mainly achieved by lithium cations. Table 2 provides the calculated lithium transference numbers for the three polymer electrolytes tested. Table 2: Calculated Lithium Transference Numbers

Table 2

[0134] Since a value of at least 0.5 is considered high in the art, it can be seen from Table 2 that the three polymer electrolytes and the reference electrolyte described in the present invention exhibit high lithium transference numbers.

[0135] Lithium conductivity is a measured value related to the conductivity achieved by lithium cations. In other words, a higher lithium transference number indicates that the difference between the ionic conductivity (measured in Example 2) and the lithium conductivity is smaller. Figure 3 shows the lithium conductivity (σ total ) compared to the ionic conductivity (σ Li + ) measured at 70 °C for the three polymer electrolytes (obtained from Compound Numbers 2, 3, and 5) tested. It is clear from Figure 3 that a high lithium conductivity of at least 2×10 -4 S / cm was measured. Furthermore, the difference between the ionic conductivity and the lithium conductivity was minimal for the polymer electrolyte obtained from Compound 5. This is consistent with this polymer electrolyte exhibiting the highest lithium transference number.

[0136] Example 4 The electrochemical anodic stability was tested by linear sweep voltammetry at 70 °C on a VMP3 potentiostat. A two-electrode setup was used, with lithium foil as the reference and counter electrodes. For this purpose, a CR2032 coin cell was prepared having lithium foil as the reference and counter electrodes and stainless steel as the working electrode. The polymer electrolytes used in the coin cell are the electrolytes obtained from Compound Numbers 3 and 5, as well as Reference Electrolyte 1 and Reference Electrolyte 4 (40 / 60) of Example 1. All other components of the CR2032 coin cell were as typically used in the art. The coin cell was assembled in an argon glove box.

[0137] Linear sweep voltammetry was performed at a scan rate of 1 mV / s from an open circuit voltage (OCV) of up to 6.0 V versus Li + / Li.

[0138] Figures 4A and 4B show the current density as a function of potential as measured for coin cells containing the polymer electrolytes obtained from Compound Numbers 3 and 5, respectively. Figures 5A and 5B show the current density as a function of potential as measured for coin cells containing Reference Polymer Electrolytes 1 and 4, respectively. It is noted that for both the polymer electrolyte of the present invention and Reference Electrolyte 1, the onset of irreversible oxidation of the system occurs at approximately 5.0 V, which means that for battery applications, the polymer electrolyte can be used in combination with or coupled to active materials operating at voltages below 5.0 V. However, for Reference Electrolyte 4 (Figure 5B), the onset of irreversible oxidation of the system occurred at approximately 3.7 V.

[0139] The electrochemical cathodic stability of the polymer electrolyte obtained in Example 1 was tested by cyclic voltammetry at 70 °C. For this purpose, two CR2032 coin cells were prepared, each having a lithium foil as the reference and counter electrode and a copper foil as the working electrode. As the electrolyte, the polymer electrolytes obtained from Compound Nos. 3 and 5 were used (one electrolyte per coin cell). All other components of the CR2032 coin cell were as typically used. The coin cells were assembled in an argon glove box.

[0140] Cyclic voltammetry was carried out at a scan rate of 1 mV / s and included 6 scans in the voltage range of 3.00 V to -0.05 V with respect to Li + / Li.

[0141] Figures 6 and 7 show the current density as a function of potential for each of the 6 cycles measured for coin cells containing the polymer electrolytes obtained from Compound Nos. 3 and 5, respectively. The intensity response is visible during the first cycle during the reduction process for both polymer electrolytes. This may be due to the reduction of the plasticizer at these voltages, which is an irreversible reduction. Cycles 2 - 6 show a stable current density pattern.

[0142] The limiting current density test was also carried out using a VMP3 potentiostat. For this purpose, two CR2032 coin cells (i.e., symmetric coin cells), each having a lithium foil as the cathode and as the anode, were prepared. As the electrolyte, the polymer electrolytes obtained from Compound Nos. 3 and 5 were used (one electrolyte per coin cell). All other components of the CR2032 coin cell were as typically used. The coin cells were assembled in an argon glove box.

[0143] While maintaining the total capacity constant at 0.2 mAh / cm 2 , from 0.1 mA / cm 2 to 5 mA / cm 2The limiting current density test was conducted by cyclically charging and discharging a coin cell at a constant current with a variable current density.

[0144] Figures 8A, 8B, and 8C show the voltage as a function of capacity as measured for a coin cell containing the polymer electrolyte obtained from Compound No. 3. The measurements were made at 70 °C, 40 °C, and 25 °C, respectively. The stable profile was observed up to a current density of 5C = 1.0 mA / cm at 70 °C 2 , 3C = 0.61 mA / cm at 40 °C 2 , and 1C = 0.2 mA / cm at 25 °C 2 .

[0145] Figures 9A, 9B, and 9C show the voltage as a function of capacity as measured for a coin cell containing the polymer electrolyte obtained from Compound No. 5. The measurements were made at 70 °C, 40 °C, and 25 °C, respectively. The stable profile was observed up to a current density of 5C = 1.0 mA / cm at 70 °C 2 , 3C = 0.61 mA / cm at 40 °C 2 , and 1C = 0.2 mA / cm at 25 °C 2 .

[0146] Additional CR2032-type symmetric coin cells (one electrolyte per coin cell) containing the polymer electrolytes obtained from Compound Nos. 3 and 5 were tested by repeated charge / discharge (cycle test) at a constant current density of 0.61 mA / cm at 70 °C while maintaining the total capacity constant at 0.2 mAh / cm 2 . Two different types of lithium foils designated as A and B were used. Type A was an unprocessed lithium metal foil 500 μm thick. Type B was a 50-μm-thick layer of lithium metal cast on a copper foil. Figure 10 shows the voltage as a function of time for the cycle test. It is clear from Figure 10 that all the cells showed a stable voltage profile for over 800 hours. 2

[0147] Example 5 From Compound No. 3, a first lithium metal battery was assembled using the polymer electrolyte obtained in Example 1. The cathode included 80% by weight of LiFePO4 (LFP), 10% by weight of the second polymaleimide polymer of Example 1, and 10% by weight of carbon black based on the total weight of the cathode. The active material loading was such that the theoretical capacity of the battery approached 1 mAh / cm 2 It was close to 2 . The voltage window for LFP is known to be 2.7 V to 3.8 V. The anode was a copper foil coated with lithium metal having 0.3 wt% aluminum doping.

[0148] The first lithium metal battery was tested by repeating charge / discharge cycles up to a maximum of 100 cycles at 70 °C (Figure 11A) and up to a maximum of 50 cycles at 40 °C (Figure 11B). From Figures 11A and 11B, it is clear that stable cycling is observed regardless of the temperature at which the test was conducted. The retention capacity is 99%, which is excellent. Throughout the test, a specific capacity close to the theoretical value was obtained, and from Figures 11A and 11B, it is clear that these are stable throughout the cycling period.

[0149] From Compound No. 3, a second lithium metal battery was assembled using the polymer electrolyte obtained in Example 1 as the electrolyte. The cathode included 80% by weight of NMC622 (nickel manganese cobalt), 10% by weight of the second polymaleimide polymer of Example 1, and 10% by weight of carbon black based on the total weight of the cathode. The active material loading was such that the theoretical capacity of the battery approached 1 mAh / cm 2 It was close to 2 . The voltage window for NMC622 is known to be 3.0 V to 4.25 V. The anode was a copper foil coated with lithium metal having 0.3 wt% aluminum doping.

[0150] The second lithium metal battery was tested by repeating charge / discharge cycles up to a maximum of 100 cycles at 70 °C (Figure 12A) and up to a maximum of 50 cycles at 40 °C (Figure 12B). It is clear from Figures 12A and 12B that the retention capacity was slightly lower than that for the first lithium metal battery, but still very high. A limited but constant loss of capacity was observed in each charge / discharge cycle, but it is clear that the polymer electrolyte of the present invention can be used with active materials that operate at high voltages with excellent performance.

[0151] Example 6 To acetone as a solvent, 0.12 g of the third polymaleimide polymer of Example 1, 0.48 g of the second polymaleimide polymer of Example 2, 0.083 g of pentaerythritol tetrakis(2-mercaptoacetate) as a thiol-ene reagent (the thiol-ene reagent described in Formula V, where η, θ, λ, and ξ are all 0), 0.6953 g of propylene carbonate, and 0.3275 g of ethylene carbonate as a plasticizer, 2-hydroxy-2-methylpropiophenone as a free radical initiator were added to prepare a further compound according to the present invention.

[0152] As a lithium salt, 0.0853 g of lithium bis-(fluorosulfonyl)imide was further added, which corresponded to 4.76% by weight based on the total weight of the compound excluding the weight of acetone.

[0153] The amount of acetone was such that the compound contained 86% by weight of acetone based on the total weight of the compound including the weight of acetone.

[0154] The compound containing acetone was then applied to a Teflon substrate by casting, more specifically solvent casting.

[0155] A Teflon substrate containing the compound was placed in an argon box, and acetone was removed by supplying an argon stream to the substrate at room temperature and atmospheric pressure for 24 hours.

[0156] Next, the compound substantially free of solvent was exposed to UV irradiation that stimulates the thiol-ene reaction, thereby obtaining a polymer electrolyte film having a thickness of 150 - 200 μm.

[0157] Using the polymer electrolyte film as the electrolyte, a first lithium metal battery was assembled. The cathode contained 80% by weight of LiFePO4 (LFP), 10% by weight of a second polymaleimide polymer, and 10% by weight of carbon black based on the total weight of the cathode. The active material loading was such that the theoretical capacity of the battery approached 1 mAh / cm 2 It was close to. The voltage window for LFP is known to be 2.7V - 3.8V. The anode was a copper foil coated with lithium metal having 0.3 wt% aluminum doping.

[0158] Using the polymer electrolyte film as the electrolyte, a second lithium metal battery was assembled. The cathode contained 80% by weight of NMC622 (nickel manganese cobalt), 10% by weight of a second polymaleimide polymer, and 10% by weight of carbon black based on the total weight of the cathode. The active material loading was such that the theoretical capacity of the battery approached 1 mAh / cm 2 It was close to. The voltage window for NMC622 is known to be 3.0V - 4.25V. The anode was a copper foil coated with lithium metal having 0.3 wt% aluminum doping.

[0159] The lithium metal battery was tested by repeating charge / discharge cycles up to a maximum of 40 cycles at 40 °C (first battery, Fig. 13A) and up to a maximum of 60 cycles (second battery, Fig. 13B). It is clear from Figs. 13A and 13B that the Coulombic efficiency (or retained capacity) was very high. A limited but constant loss of capacity was observed in each charge / discharge cycle, but it is clear that the polymer electrolyte of the present invention can be used with active materials that operate at high voltages with excellent performance.

Claims

1. A polymer electrolyte for a battery, wherein - A first polymaleimide polymer comprising a first polymaleimide repeating unit, wherein the first polymaleimide repeating unit is R 3 (Q) μ (wherein R 3 is, individually, C(H) h (C x H 2x+1 ) i ((CH 2 ) ψ ) j (CH 2 OC(O)(CH 2 ) σ ) k or a polyether (where i is from 0 to 2; j and k are, individually, from 0 to 4; h is 4 - i - j - k; the sum of h and i is from 0 to 2; x is from 1 to 6; ψ is from 1 to 10; σ is from 1 to 20); μ is individually at least 2, preferably 2 - 4, Q is individually of formula (I): 【Chemical 1】 (wherein R 2 is, individually, C 1 to C 16 alkyl, C 2 to C 16 alkenyl, C 2 to C 16 alkynyl or aryl, and R 4 individually is H, C 1 to C 16 alkyl, C 2 to C 16 alkenyl, C 2 to C 16 alkynyl, and Q is covalently bonded to R through the sulfur atom of Q 3 by (by) with the first polymaleimide polymer according to - formula (II) 【Chemical Formula 2】 (wherein R 1 each independently is H, C 1 to C 16 alkyl, C 2 to C 16 alkenyl, C 2 to C 16 alkynyl, and m is individually 1 - 5, M + is an alkali metal ion independently, and X is, independently, H, F, C 1 ~C 16 alkyl, C 1 ~C 16 fluoroalkyl) with a second polymaleimide polymer containing a second polymaleimide repeating unit according to comprising a polymer electrolyte.

2. The polymer electrolyte according to claim 1, wherein the molar ratio of the first polymaleimide polymer to the second polymaleimide polymer is 5 - 95, preferably 20 - 50.

3. R 2 The polymer electrolyte according to claim 1, wherein R is methyl, ethyl, propyl, n-butyl, isobutyl, benzyl, or styryl.

4. The polymer electrolyte according to claim 1, wherein the alkali metal ion is a lithium ion.

5. X is CF 3 , CH 3 or F, the polymer electrolyte according to claim 1.

6. R 3 is a polyether by -(CH 2 ) ω (O(CH 2 ) sigma ) α -, where ω is 0 to 4, sigma is 1 to 4, and α is 1 to 10, the polymer electrolyte according to claim 1.

7. R 3 is -(CH 2 ) β -, C(CH 2 CH 3 )(CH 2 OC(O)(CH 2 ) σ ) 3 - or C(CH 2 OC(O)(CH 2 ) σ ) 4 -, where β is from 1 to 20 and σ is from 1 to 20, the polymer electrolyte according to claim 1.

8. The polymer electrolyte according to claim 1, further comprising 0.5 wt% - 90 wt%, preferably 30 wt% - 80 wt% of a plasticizer based on the total weight of the polymer electrolyte.

9. The polymer electrolyte according to claim 8, wherein the plasticizer is selected from the group consisting of linear carbonates, cyclic carbonates, ethers, and nitriles.

10. A battery comprising the polymer electrolyte according to claim 1.

11. A method for manufacturing a polymer electrolyte for a battery, wherein the polymer electrolyte comprises a first polymaleimide polymer and a second polymaleimide polymer, and the method comprises: - a third polymaleimide polymer containing a third polymaleimide repeating unit, wherein the third polymaleimide repeating unit is of formula (III) 【Number】 (wherein R 2 is, individually, C 1 to C 16 alkyl, C 2 to C 16 alkenyl, C 2 to C 16 alkynyl or aryl, and R 4 is, individually, H, C 1 to C 16 alkyl, C 2 to C 16 alkenyl, C 2 to C 16 alkynyl) with a third polymaleimide polymer according to a second polymaleimide polymer containing a second polymaleimide repeating unit, wherein the second polymaleimide repeating unit is of formula (II), with a second polymaleimide polymer, a thiol - ene reactant containing q thiol groups, where q is at least 2, a free radical initiator, optionally a processing solvent, preparing a compound comprising - applying the compound to a substrate, - when the compound comprises a processing solvent, removing the processing solvent, thereby obtaining a substantially processing - solvent - free compound. - exposing the (substantially processing solvent-free) compound to one or more of UV irradiation, IR irradiation, or a temperature up to 100 °C to initiate a thiol-ene reaction of the thiol-ene reagent and the third polymaleimide repeating unit, thereby obtaining the polymer electrolyte; comprising 【Number 1】 wherein a is the number of thiol-ene reagent molecules and n is the number of third polymaleimide repeating units in the compound), method. **Claim 12** The method according to claim 11, wherein the compound further comprises a plasticizer. **Claim 13** The method according to claim 11, wherein the compound comprises 0 wt% to 80 wt% plasticizer, 3 wt% to 45 wt% combined third polymaleimide polymer and the thiol-ene reagent, 1% to 45% second polymaleimide polymer, 0.05 wt% to 1.5 wt% free radical initiator, based on the total weight of the compound minus the weight of the optional solvent. **Claim 14** The method according to claim 11, wherein the optional processing solvent comprises acetone, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, or a combination of two or more thereof. **Claim 15** The method according to claim 11, wherein the compound comprises 0 wt% to 95 wt%, preferably 10 wt% to 90 wt% processing solvent, based on the total weight of the compound including the weight of the processing solvent.

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