Ion-conducting polymers for gel polymer electrolytes and gel polymer electrolytes comprising such ion-conducting polymers

Abstract

The present invention relates to an ion conducting polymer for a gel polymer electrolyte comprising m repeating units as shown in formula (I) and n repeating units as shown in formula (II) wherein R1 is (CH2) x-R3 wherein x is 1 to 20 and R3 is H or CN; r2 and R5 are independently a C1-C10 alkyl group or a C2-C10 alkenyl group; m is an alkali metal or alkaline earth metal; the ratio of m to n (m / n) is 25: 1 to 1: 25; and m + n is q, wherein q is from 50 to 5000. The invention also relates to a gel polymer electrolyte comprising the ionically conductive polymer, and to a process for preparing the ionically conductive polymer. (I) (II)

Description

Technical Field

[0001] This invention relates to ion-conducting polymers for use in gel polymer electrolytes in battery packs. The invention also relates to gel polymer electrolytes comprising such ion-conducting polymers, and to methods for preparing said ion-conducting polymers. Background Technology

[0002] Over the past decade, there has been significant focus on the shift from liquid electrolytes in battery packs to non-liquid electrolytes such as gel polymer electrolytes and solid electrolytes. This shift offers clear advantages, such as improved safety by mitigating the risks of leakage and combustion, and improved battery life and performance by enhancing structural stability and reducing degradation.

[0003] Gel polymer electrolytes (GPEs) have attracted considerable attention due to their unique combination of solid-like mechanical stability and liquid-like ionic conductivity. In these electrolytes, the polymer matrix is ​​an essential component, as it contributes to maintaining structural integrity while providing specific flexibility to the electrolyte and improving ionic conductivity, which in turn contributes to improved battery performance and lifespan.

[0004] However, although gel polymer electrolytes (GPEs) exhibit better ionic conductivity than solid electrolytes, they are still lower than those of liquid electrolytes, which limits the performance of battery packs containing such GPEs. They also tend to encounter issues related to long-term stability and compatibility with electrode materials, affecting the efficiency and lifespan of the energy storage system. Furthermore, the presence of plasticizers and optional solvents can sometimes cause phase separation or crystallization, leading to a decline in GPE performance over time.

[0005] US11848417 discloses a gel polymer electrolyte comprising a crosslinked network, an ionic liquid, and one or more lithium salts. The crosslinked network is a reaction product of an inorganic cage-type oligomeric silsesquioxane with a functionalized polyethylene glycol or a functionalized polyethylene oxide, and an amine-terminated bifunctionalized polyethylene glycol or an amine-terminated bifunctionalized polyethylene oxide.

[0006] EP4372026 discloses an ion-conducting polymer binder for bonding inorganic solid electrolytes together, thereby reducing the cathode / electrolyte interfacial resistance and improving metal ion mobility. The electrolyte comprises this polymer binder and metal ions, preferably lithium ions. The polymer can be polyester, polyethylene, anionic polymer, polycarbonate, polysiloxane, such as 3D crosslinked aliphatic polycarbonate. Summary of the Invention

[0007] The object of this invention is to overcome one or more of the aforementioned disadvantages. One object of this invention is to provide an ion-conducting polymer for gel polymer electrolytes (GPEs) that simultaneously possesses excellent ionic conductivity and high thermal stability and heat resistance, as well as excellent resistance to high voltage (i.e., high oxidative stability).

[0008] Another object of the present invention is to provide an ionically conductive polymer for use in gel polymer electrolytes, wherein the electrolyte has sufficient mechanical strength to make it self-supporting (defined as being able to be handled and controlled without damage or degradation and without requiring a support), even when the gel polymer electrolyte contains a large amount of plasticizer. Another object is to provide an ionically conductive polymer that contains a significantly reduced amount of halogen atoms, and is therefore considered to have greater sustainability.

[0009] One objective is to provide a method for preparing the polymer that uses as few harmful solvents as possible, or even none at all, i.e., a method with greater sustainability.

[0010] Another objective is to provide gel polymer electrolytes (GPEs) comprising such ionicly conductive polymers, which exhibit excellent mechanical strength and heat resistance, and excellent ionic conductivity, particularly single-ion conductivity, even under high loads, resulting in excellent rate capability and excellent cycle stability, while simultaneously containing a significantly reduced amount of halogen atoms compared to prior art GPEs. A particular objective is to provide self-supporting GPEs that can contain a significant amount of plasticizer. Another objective is to provide a less complex method for preparing said GPEs, particularly a method that does not require any post-curing to enable the GPE to be self-supporting.

[0011] In light of this disclosure, when referring to or referencing an electrolyte, the electrolyte is a gel polymer electrolyte (GPE). In this disclosure, the term "gel polymer electrolyte" is used for polymer electrolytes containing plasticizers.

[0012] A first aspect of the present invention discloses an ion-conducting polymer for use in gel polymer electrolytes (GPEs), as described in the appended claims.

[0013] The ion-conductive polymer adhesive comprises m repeating units as shown in formula (I):

[0014] (I),

[0015] Where R1 is (CH2) x -R3, where x is 1 to 20, R3 is H or CN; and R2 is C1-C 10 Alkyl or C2-C 10 Alkenyl group.

[0016] The ion-conductive polymer adhesive also contains n repeating units as shown in formula (II):

[0017] (II),

[0018] R2 and R5 are independently C1-C 10 Alkyl or C2-C 10 Alkenyl group; and M is an alkali metal or alkaline earth metal.

[0019] In other words, the ion-conducting polymer adhesive is a copolymer comprising m repeating units as shown in formula (I) and n repeating units as shown in formula (II).

[0020] The ratio of m to n, that is, the ratio of the number of repeating units as shown in formula (I) to the number of repeating units as shown in formula (II), is 25:1 to 1:25, preferably 20:1 to 1:20, more preferably 10:1 to 1:10, most preferably 5:1 to 1:5, for example 4:1 to 1:4, 1:2 to 2:1, for example 1.4:1.

[0021] The total number of repeating units m + n or q is 50 to 5000, preferably 75 to 4500, and more preferably 100 to 4000.

[0022] A first particularly preferred example of an ion-conducting polymer adhesive is a polymer in which x is 6, R3 is CN, R2 is (CH2)2, and R5 is (CH2)2. A second particularly preferred example of an ion-conducting polymer adhesive is a polymer in which x is 10, R3 is H, R2 is (CH2)2, and R5 is (CH2)2.

[0023] Advantageously, M is Li, Na or Mg, with Li being preferred.

[0024] The inventors have surprisingly discovered that, when used in gel polymer electrolytes (GPEs), the ion-conducting polymer of this invention acts as an ion source for alkali metals or alkaline earth metals M, particularly Li, Na, or Mg, with Li being preferred. This gives the GPE of this invention excellent single-ion conductivity, meaning that lithium ions are primarily responsible for charge transport in the GPE of this invention, and reduces side reactions caused by other ionic substances.

[0025] A second aspect of the invention discloses a gel polymer electrolyte for battery packs, as described in the appended claims. The gel polymer electrolyte comprises, or is substantially composed of, a plasticizer and an ion-conducting polymer according to the first aspect.

[0026] Advantageously, the gel polymer electrolyte contains 10% to 90% by weight, preferably 20% to 80% by weight, more preferably 25% to 75% by weight, or, for example, 35% to 65% by weight, based on the total weight of the gel polymer electrolyte.

[0027] Advantageously, the gel polymer electrolyte comprises 90% to 10% by weight, preferably 80% to 20% by weight, more preferably 75% to 25% by weight, or, for example, 65% to 35% by weight of the ion-conducting polymer according to the first aspect of the invention, based on the total weight of the gel polymer electrolyte.

[0028] Advantageously, the gel polymer electrolyte comprises or is substantially composed of: 10% to 90% by weight, preferably 20% to 80% by weight, more preferably 25% to 75% by weight, for example 35% to 65% by weight, of a plasticizer; and 90% to 10% by weight, preferably 80% to 20% by weight, more preferably 75% to 25% by weight, for example 65% to 35% by weight, of an ion-conducting polymer according to the first aspect of the invention, based on the total weight of the gel polymer electrolyte.

[0029] Advantageously, in the gel polymer electrolyte, the sum of the weight percentages of the ion-conducting polymer and the plasticizer is 100%, meaning the gel polymer electrolyte advantageously consists essentially of a plasticizer and the ion-conducting polymer according to the first aspect of the invention. For example, the gel polymer electrolyte may consist of 40% by weight of plasticizer and 60% by weight of the ion-conducting polymer of the present invention.

[0030] The inventors have discovered that gel polymer electrolytes containing equal to or less than 10% by weight, preferably equal to or less than 15% by weight, more preferably equal to or less than 20% by weight of plasticizer are brittle and have low mechanical strength, i.e., they are prone to breakage during handling and have limited flexural properties. This is believed to be due to the limited amount of plasticizer.

[0031] It should be understood that the optimal amounts of plasticizer and the ionically conductive polymer depend on the composition (structure) of the plasticizer and the structure of the polymer, particularly the m / n ratio, the composition of repeating units, and the total number of repeating units (and consequently, the molecular weight of the polymer). As a result, gel polymer electrolytes with properties that can be improved according to application and requirements can be provided. In other words, the advantage of the ionically conductive polymers and gel polymer electrolytes described in this invention is that they offer a wide range of properties that can be optimized according to requirements, not only by changing the relative amounts of plasticizer and polymer but also by changing the structure of the polymer itself.

[0032] Advantageously, the ion-conducting polymer is present at least partially as a matrix in the gel polymer electrolyte, wherein the plasticizer is at least partially, preferably substantially entirely, dispersed within the matrix. More particularly, advantageously at least 20%, preferably at least 25%, more preferably at least 50%, most preferably at least 75%, for example at least 80%, at least 90%, at least 95%, or substantially 100% of the ion-conducting polymer is present as a matrix in the gel polymer electrolyte.

[0033] Advantageously, the plasticizer is propylene carbonate. Advantageously, based on the total weight of the gel polymer electrolyte, the gel polymer electrolyte comprises 20% to 60% by weight of propylene carbonate and 80% to 40% by weight of the ionically conductive polymer according to the first aspect, or is substantially composed of them. Advantageously, the gel polymer electrolyte comprises a matrix of the ionically conductive polymer and propylene carbonate dispersed within the matrix as a plasticizer.

[0034] A third aspect of the invention relates to a battery pack, as described in the appended claims. The battery pack comprises a gel polymer electrolyte as described in the second aspect. Advantageously, the battery pack is a secondary battery. Advantageously, the battery pack is a lithium-ion battery.

[0035] A fourth aspect of the present invention discloses a method for preparing an ion-conducting polymer, as described in the appended claims. The ion-conducting polymer is the ion-conducting polymer described in the first aspect of the present invention.

[0036] The method includes reacting an amino derivative according to H2N-R1 with a polymer comprising q repeating units as shown in formula (III), wherein R1 is as described above.

[0037] (III), wherein R2 is as described above, and q is 50 to 5000, preferably 75 to 4500, more preferably 100 to 4000.

[0038] The reaction was carried out in the presence of dimethylformamide (DMF).

[0039] The reaction is carried out at a temperature T1 of 15°C to 50°C, more preferably 15°C to 30°C, for example, room temperature.

[0040] This reaction results in the formation of a first intermediate polymer. Advantageously, the first intermediate polymer does not contain closed rings in its molecular structure, particularly imide rings. Advantageously, the first intermediate polymer comprises n repeating units as shown in formula (III) and m repeating units as shown in formula (IV):

[0041] (IV), where m + n equals q; and the ratio of m to n is as described above.

[0042] The first intermediate polymer was then reacted with F3CO2SN. - O2S-R4-NH2 M + The reaction, in which R4 and M are as described above.

[0043] The reaction takes place in the presence of DMF.

[0044] The reaction is carried out at a temperature T2 of 15°C to 50°C, more preferably 15°C to 30°C, for example, room temperature.

[0045] This reaction leads to the formation of a second intermediate polymer. Advantageously, the second intermediate polymer does not contain closed rings in its molecular structure, particularly imide rings. Advantageously, the second intermediate polymer comprises m repeating units as shown in formula (IV) and n repeating units as shown in formula (V):

[0046] (V), where m + n equals q; and the ratio of m to n is as described above.

[0047] The second intermediate polymer then undergoes imide ring closure, thereby forming an ion-conducting polymer. The imide ring closure step can be carried out by heating the second intermediate polymer to a temperature T3, which is higher than temperature T2, and then increasing the temperature from T3 to T4 (i.e., further heating). Alternatively, the imide ring closure step can be carried out at T2 in the presence of a catalyst. In other words, imide ring closure using a catalyst can be carried out without heating the second intermediate polymer.

[0048] Advantageously, the temperature T3 is 30°C to 80°C, preferably 35°C to 70°C, more preferably 40°C to 60°C, for example 50°C.

[0049] Advantageously, the temperature T4 is 100°C to 250°C, preferably 125°C to 200°C, and more preferably 150°C to 180°C.

[0050] Advantageously, this operation is carried out in the presence of DMF when the imide ring is closed by heating a second intermediate polymer.

[0051] Advantageously, when the imide ring is closed in the presence of a catalyst, the catalyst comprises carbonyl diimidazole, or is essentially composed of carbonyl diimidazole.

[0052] This disclosure also relates to the use of the ion-conducting polymer according to the first aspect in a mixture for the preparation of the gel polymer electrolyte according to the second aspect. Attached Figure Description

[0053] The invention will now be described in more detail with reference to the accompanying drawings, wherein like reference numerals in the drawings denote like features, and wherein:

[0054] - Figure 1 The H-NMR spectrum of the second ion-conducting polymer of the present invention is shown;

[0055] - Figure 2 The FTIR spectrum of the second polymer is shown;

[0056] - Figure 3 The TGA analysis of the second polymer is shown;

[0057] - Figure 4 The DSC analysis of the second polymer is shown;

[0058] - Figure 5 The LSV analysis of the second polymer is shown;

[0059] - Figure 6 and Figure 7 The thermal stability (heat resistance) of the six gel polymer electrolytes of this invention, as determined by TGA, is shown.

[0060] - Figure 8 and Figure 9 The glass transition temperatures of the six gel polymer electrolytes of this invention, as determined by DSC, are shown.

[0061] - Figure 10 and Figure 11 The ionic conductivity of four gel polymer electrolytes of the present invention is shown. Detailed Implementation

[0062] The ion-conducting polymer is a copolymer and contains m repeating units as shown in formula (I) and n repeating units as shown in formula (II):

[0063] (I), and (II),

[0064] in

[0065] R1 is (CH2) x -R3, wherein x is 1 to 20, preferably 2 to 15, more preferably 4 to 10, and wherein R3 is H or CN;

[0066] R2 and R5 are independently C1-C 10 Alkyl or C2-C 10 alkenyl groups; and

[0067] M is an alkali metal or an alkaline earth metal.

[0068] Advantageously, m and n are chosen such that the total number q of repeating units is 50 to 5000, preferably 75 to 4500, more preferably 100 to 4000, said total number q being equal to m + n.

[0069] Advantageously, m is 5 to 4500, preferably 10 to 3600. Advantageously, n is 5 to 4500, preferably 10 to 3600.

[0070] Advantageously, the molecular weight of the ion-conducting polymer of the present invention is 10 to 3000 kDa, preferably 11 to 2500 kDa, more preferably 12 to 2000 kDa, and most preferably 13 to 1800 kDa.

[0071] It should be understood that the values ​​of m and n, i.e., the number of repeating units as shown in formula (I) and the number of repeating units as shown in formula (II), depend on the total number of repeating units q, and the ratio of m to n, i.e., the ratio of the number of repeating units as shown in formula (I) to the number of repeating units as shown in formula (II). For example, when q is 3000 and m:n is 2:1, the copolymer contains 2000 repeating units as shown in formula (I) and 1000 repeating units as shown in formula (II). When q is 5000 and m:n is 1:1, the copolymer contains 2500 repeating units as shown in formula (I) and 2500 repeating units as shown in formula (II).

[0072] The repeating units shown in Formula (II) define the ionic conductivity of the polymer, while the repeating units shown in Formula (I) are responsible for matrix-forming properties, i.e., the inclusion of a plasticizer in the gel polymer electrolyte of the present invention. It should be understood that, for a constant total number of repeating units q, the ionic conductivity of the ionicly conductive polymer can be altered by changing the ratio of m to n. This provides a very wide variety of ionicly conductive polymers, allowing for fine-tuning of their properties based on other components in the gel polymer electrolyte, particularly the plasticizer.

[0073] R1 can be linear or branched, i.e., (CH2). x - The chain can be linear or branched. Advantageously, R1, i.e. (CH2), x - The chain is a straight chain.

[0074] R2 can be linear or branched. Advantageously, R2 is based on (CH2). y C1-C 10 Alkyl, wherein y is 1 to 10, preferably 1 to 4, more preferably 1 or 2, i.e. CH2 or (CH2)2.

[0075] R5 can be linear or branched. Advantageously, R5 is based on (CH2). w C1-C 10Alkyl, wherein w is 1 to 10, preferably 1 to 4, more preferably 1 or 2, i.e. CH2 or (CH2)2.

[0076] Advantageously, the copolymer is a random copolymer, i.e., the repeating units as shown in formulas (I) and (II) are randomly distributed in the copolymer. Alternatively, more advantageously, the copolymer is a block copolymer, i.e., the copolymer comprises one or more “blocks” of repeating units as shown in formula (I) and one or more “blocks” of repeating units as shown in formula (II). An example of such a copolymer is represented by the structure of formula (VI):

[0077] (VI), wherein the copolymer comprises a block of n repeating units as shown in formula (II) and a block of m repeating units as shown in formula (I).

[0078] An example of an ion-conducting polymer is a block copolymer in which x is 6, R3 is CN, R2 is (CH2)2, and R5 is (CH2)2, and in particular, M is Li:

[0079] .

[0080] A second example of an ion-conducting polymer is a block copolymer in which x is 10, R3 is H, R2 is (CH2)2, and R5 is (CH2)2, and in particular, M is Li:

[0081] .

[0082] When x is 6, R3 is CN and R2 is (CH2)2, the first intermediate polymer and the second intermediate polymer advantageously have the structures shown in formula (VII) and formula (VIII), respectively:

[0083] (VII), and (VIII).

[0084] For example, when x is 10, R3 is H and R2 is (CH2)2, the first intermediate polymer and the second intermediate polymer advantageously have the structures shown in formula (IX) and formula (X), respectively:

[0085] (IX), and (X).

[0086] Advantageously, the ion-conducting polymers of the present invention exhibit high heat resistance, i.e., they can withstand temperatures of at least 250°C, preferably at least 300°C, and more preferably at least 350°C, as determined by thermogravimetric analysis (TGA) performed at a heating rate of 10°C / min in an Ar flow of 60 mL / min. The inventors have surprisingly discovered that the heat resistance of the ion-conducting polymers does not change significantly when the m:n ratio of the polymer is altered.

[0087] It should be understood that the glass transition temperature of the ionically conductive polymer is defined by the number of repeating units in formula (I) and formula (II), and more particularly by the ratio of the number of repeating units m to n. Advantageously, the glass transition temperature of the polymer of the present invention is 30°C to 175°C, preferably 50°C to 150°C, more preferably 80°C to 120°C, for example 90°C to 110°C, which is measured by differential scanning calorimetry (DSC) in an Ar atmosphere under a heating scan of 10°C / min for two cycles from -80°C to greater than 200°C, wherein the result is obtained in the second cycle to ensure that the thermal history of the polymer has been eliminated, thereby ensuring a reliable and reproducible glass transition temperature value. It should be understood that the actual glass transition temperature of the ionically conductive polymer depends on the ratio of m to n.

[0088] Advantageously, the ion-conducting polymer has high oxidative stability of at least 2.5 V, preferably at least 3 V, more preferably at least 4 V, for example at least 4.5 V, which is achieved by maintaining a stability of 1 mV s in a propylene carbonate solution at room temperature. -1 The linear sweep voltammetry (LSV) method was used for analysis and determination.

[0089] The gel polymer electrolyte of the present invention comprises a plasticizer and the ion-conducting polymer of the present invention, or is composed of these components.

[0090] Plasticizers can be any organic solvent known in the art. Non-limiting examples of suitable plasticizers include linear carbonates, cyclic carbonates, ethers, and nitriles. Preferred plasticizers for use with the ion-conducting polymers of the present invention include propylene carbonate and ethylene carbonate, with propylene carbonate being preferred.

[0091] The gel polymer electrolyte according to the invention can be prepared by methods known in the art. A preferred method includes preparing a mixture comprising an ionically conductive polymer, a plasticizer, and a solvent, solvent casting the mixture, evaporating the solvent used to prepare the mixture, and optionally drying. Another exemplary method is the so-called dry process, which includes mixing the ionically conductive polymer and the plasticizer, then extruding the mixture, optionally followed by calendering or lamination. Advantageously, the method for preparing the gel polymer electrolyte of the invention does not require a curing step as a final step to make the electrolyte self-supporting.

[0092] The inventors have surprisingly discovered that when M in the repeating unit of formula (II) of the ion-conducting polymer is lithium, the gel polymer electrolyte of the present invention has a lithium-ion transference number (LTN) close to that of (1). In other words, lithium ions are primarily responsible for charge transport in the gel polymer electrolyte of the present invention and reduce side reactions caused by other ionic substances, i.e., the gel polymer electrolyte has excellent single-ion conductivity. In other words, the gel polymer electrolyte of the present invention allows for uniform lithium deposition and reduces system polarization, while improving efficiency and cycle stability in battery cells containing the gel polymer electrolyte. Not wishing to be limited by any theory, the inventors believe this is a result of the ion-conducting polymer containing Li (M in formula (II) is Li). Similarly, the same result is obtained when M is other alkali metals or alkaline earth metals such as Na or Mg, with Li showing the most significant effect.

[0093] Advantageously, the gel polymer electrolytes of the present invention exhibit excellent heat resistance, i.e., they can withstand temperatures of at least 100°C, preferably at least 120°C, and more preferably at least 130°C, as determined by a TGA test performed at 10°C / min in an Ar flow of 60 mL / min. Advantageously, the heat resistance depends on the nature (i.e., its chemical structure) of the plasticizer in the electrolyte. Consequently, the plasticizer used in the gel polymer electrolyte can be modified according to the desired heat resistance.

[0094] It should be understood that the glass transition temperature of a gel polymer electrolyte depends on the amount of plasticizer, as plasticizers are used to reduce the brittleness of the polymer material, which is achieved by lowering the glass transition temperature. Advantageously, the glass transition temperature of a gel polymer electrolyte lies between an unmeasurable value (with a large amount of plasticizer) and the glass transition temperature of ionically conductive polymers (without plasticizer).

[0095] It should be understood that the ionic conductivity of gel polymer electrolytes is greater than that of ion-conducting polymers. This is attributed to the presence of plasticizers, which result in higher flexibility in gel polymer electrolytes. In other words, the ionic conductivity of gel polymer electrolytes increases with increasing plasticizer content.

[0096] Advantageously, the gel polymer electrolyte has a strength equal to or greater than 10 at room temperature (25°C). -6 The ionic conductivity S / cm is preferably equal to or greater than 5 x 10⁻⁶. -6 S / cm, for example, equal to or greater than 10 -5 S / cm, or equal to or greater than 5 x 10 -5 S / cm.

[0097] Advantageously, the gel polymer electrolyte has a strength equal to or greater than 10 at 70°C. -5The ionic conductivity S / cm is preferably equal to or greater than 2 x 10⁻⁶. -5 S / cm, for example, equal to or greater than 5 x 10 -5 S / cm, or equal to or greater than 10 -4 S / cm.

[0098] Example

[0099] Example 1

[0100] H2N-(CH2)9-CH3 as an amino derivative and containing q repeating units The polymer was reacted at room temperature in the presence of DMF for 2 hours, where q was between 100 and 4000. The resulting intermediate polymer was then reacted with F3CO2SN. - O2S(CH2)2NH2 Li + The reaction was carried out at room temperature in the presence of DMF for 2 hours. Then, the resulting reaction product was heated to 50°C in the presence of DMF for 4 hours, and then heated to 170°C in the presence of DMF for 16 hours.

[0101] The resulting ion-conducting polymer had an m:n ratio of 1.4:1. A second polymer with an m:n ratio of 1:2.85 was prepared in the same manner.

[0102] Figure 1 and Figure 2 The H-NMR and FTIR spectra of the ion-conducting polymer with an m / n ratio of 1.4:1 are shown respectively.

[0103] Figure 3 TGA analysis of a polymer with an m / n ratio of 1.4:1 shows high heat resistance above 300°C. Figure 4 DSC analysis of a polymer with an m / n ratio of 1.4:1 shows a glass transition temperature of 91 °C. Figure 5 LSV analysis of a polymer with an m / n ratio of 1.4:1 shows high oxidative stability of at least 5 V.

[0104] Example 2

[0105] Gel polymer electrolytes were prepared using the two ion-conducting polymers obtained in Example 1 (m / n ratios of 1.4:1 and 1:2.85). This was carried out by mixing each polymer with propylene carbonate as a plasticizer in a solvent, then casting the mixture onto a Teflon substrate, evaporating the solvent, and drying the resulting gel polymer electrolyte. Propylene carbonate was used in three different amounts: 20 wt% (80 wt% of polymer), 40 wt% (60 wt% of polymer), and 60 wt% (40 wt% of polymer).

[0106] For both ion-conducting polymers, the gel polymer electrolyte containing 20 wt% propylene carbonate was found to be brittle, while the gel polymer electrolyte containing 60 wt% propylene carbonate was very viscous and even tended to flow. The gel polymer electrolyte containing 40 wt% propylene carbonate was found to be viscous, but uncontrollable, especially for the gel polymer electrolyte containing polymers with an m / n ratio of 1:2.85.

[0107] The thermal stability of all six gel polymer electrolytes was determined by TGA (based on three plasticizer / polymer ratios and two m / n ratios of the polymer). Figure 6 and Figure 7 Results for electrolytes with polymers having m / n ratios of 1.4:1 and 1:2.85 are shown, varying with the weight percentage of propylene carbonate (“PC”). TGA graphs (mass loss as a function of temperature) of the reference polymer (“copolymer”) are also shown. Temperature for thermal stability was defined as the temperature at which a 5% mass loss of the gel polymer electrolyte was detected. All six electrolytes were stable at temperatures at least 130 °C. It is noted that thermal stability decreased with increasing propylene carbonate content, but the effect of the m / n ratio of the ion-conducting polymer was found to be limited.

[0108] The glass transition temperatures (T0) of the same six gel polymer electrolytes were also measured by DSC. g ). Figure 8 and Figure 9 The results for the electrolytes of polymers with m / n ratios of 1.4:1 and 1:2.85 are shown, varying with the weight percentage of propylene carbonate (“PC”). TGA graphs for the polymer (“copolymer”) used as a reference are also shown. Because the plasticizer (propylene carbonate) plasticizes the system, the plasticizer reduces the TGA of the electrolyte compared to the case with only the polymer (“copolymer”). g Consequently, higher levels of propylene carbonate lead to lower T levels. g For electrolytes containing 60% propylene carbonate, T cannot be determined. gFor electrolytes containing polymers with an m / n ratio of 1.4:1, the T value is only for the polymer. g It is a 91℃ electrolyte containing 20% ​​by weight propylene carbonate and 40% by weight propylene carbonate. g The temperatures are 42℃ and 6℃, respectively. For electrolytes with a polymer having an m / n ratio of 1:2.85, the temperature T when only the polymer is present is... g It is a T at 135℃, containing 20% ​​by weight of propylene carbonate electrolyte and 40% by weight of propylene carbonate electrolyte. g The temperatures are 52℃ and 27℃, respectively. In other words, polymers with more repeating units as shown in formula (II) are more effective against T. g It has a positive impact. This is believed to be because the repeating unit of formula (I) contributes to the flexibility of the polymer, while the repeating unit of formula (II) does not make a significant contribution to flexibility.

[0109] The ionic conductivity of four gel polymer electrolytes was also tested at temperatures ranging from 25°C to 70°C. The tested electrolytes contained 40 wt% and 60 wt% propylene carbonate, respectively, and had polymers with m / n ratios of 1.4:1 and 1:2.85. Figure 10 and Figure 11 Results for electrolytes with polymers having m / n ratios of 1.4:1 and 1:2.85 are shown, varying with the weight percentage of propylene carbonate (“PC”). A gel polymer electrolyte containing 40 wt% propylene carbonate showed a viscosity below 5 x 10⁻⁶ at 25 °C. -6 S / cm and below 5 x 10 at 70°C -5 The low ionic conductivity of S / cm is observed in the gel polymer electrolyte containing 60 wt% propylene carbonate, while it shows a conductivity greater than 5 x 10⁻⁶ at 25 °C. -5 S / cm, or even about 10 -4 S / cm and above 5 x 10 at 70°C -4 Excellent ionic conductivity of S / cm.

Claims

1. An ion-conducting polymer for use in gel polymer electrolytes, comprising m repeating units as shown in formula (I) and n repeating units as shown in formula (II): (I), and (II), in R1 is (CH2) x -R3, where x is from 1 to 20, and R3 is H or CN; R2 and R5 are independently C1-C 10 Alkyl or C2-C 10 Alkenyl; M is an alkali metal or an alkaline earth metal; The ratio of m to n (m / n) is between 25:1 and 1:25; and m + n is q, where q is between 50 and 5000.

2. The ion-conducting polymer according to claim 1, wherein x is 6, R3 is CN, R2 is (CH2)2, and R5 is (CH2)2.

3. The ion-conducting polymer according to claim 1, wherein x is 10, R3 is H, R2 is (CH2)2, and R5 is (CH2)2.

4. The ion-conducting polymer according to any one of the preceding claims, wherein M is Li, Na or Mg, preferably Li.

5. The ion-conducting polymer according to any one of the preceding claims, wherein m / n is 10:1 to 1:10, preferably 5:1 to 1:

5.

6. A gel polymer electrolyte comprising a plasticizer and an ion-conducting polymer according to any one of the preceding claims.

7. The gel polymer electrolyte of claim 6, wherein the ion-conducting polymer is present at least partially as a matrix, and wherein the plasticizer is dispersed within the matrix.

8. The gel polymer electrolyte according to any one of claims 6-7, comprising 10% to 80% by weight of a plasticizer and 90% to 20% by weight of an ion-conducting polymer based on the total weight of the gel polymer electrolyte.

9. The gel polymer electrolyte according to any one of claims 6-8, wherein the plasticizer comprises propylene carbonate.

10. The gel polymer electrolyte of claim 9, comprising 20% ​​to 60% by weight of propylene carbonate and 80% to 40% by weight of an ion-conducting polymer based on the total weight of the gel polymer electrolyte.

11. A battery pack comprising a gel polymer electrolyte according to any one of claims 6-10, preferably wherein the battery pack is a lithium-ion secondary battery.

12. A method for preparing an ion-conducting polymer according to any one of claims 1-5, comprising: - The amino derivative according to H2N-R1 is reacted with a polymer containing q repeating units as shown in formula (III) at a temperature T1 of 15°C to 50°C in the presence of dimethylformamide (DMF), thereby forming the first intermediate polymer. Where R1 is (CH2) x -R3, where x is from 1 to 20, and R3 is H or CN. (III), Where R2 is C1-C 10 Alkyl or C2-C 10 Alkenyl groups; and q is between 50 and 5000. - Make the first intermediate polymer with F3CO2SN - O2S-R5-NH2 M + The reaction, occurring in the presence of DMF at temperatures ranging from 15°C to 50°C (T2), yields a second intermediate polymer, wherein R5 is a C1-C2 bond. 10 Alkyl or C2-C 10 Alkenyl group, and M is an alkali metal or alkaline earth metal. - The second intermediate polymer undergoes imide ring closure, thereby forming an ion-conducting polymer adhesive. The closure of the imide ring is carried out by heating the second intermediate polymer to a temperature T3 of 30°C to 80°C in the presence of DMF, and then raising the temperature from T3 to a temperature T4 of 100°C to 250°C, or by doing so at T2 in the presence of a catalyst.

13. The method of claim 12, wherein the first intermediate polymer comprises n repeating units as shown in formula (III) and m repeating units as shown in formula (IV): (IV), in which m + n equals q; and The ratio of m to n is between 25:1 and 1:

25.

14. The method of claim 13, wherein the second intermediate polymer comprises m repeating units as shown in formula (IV) and n repeating units as shown in formula (V): (V), where m + n equals q; and The ratio of m to n is between 25:1 and 1:

25.

15. The method according to any one of claims 11-14, wherein M is Li, Na or Mg.

16. The method according to any one of claims 11-15, wherein the imide ring is closed at T2 in the presence of a catalyst, wherein the catalyst comprises carbonyl diimidazole.

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