Polymer-based electrolyte and method for obtaining same

Abstract

The present invention relates to a polyoxazoline-based electrolyte and a network formed by crosslinking the polyoxazoline-based electrolyte with an epoxy resin via the secondary amine groups of the polyoxazoline-based electrolyte. The network is designed as a multifunctional energy storage system capable of transporting mobile lithium cations through channels present in the structure of the network. The present invention also relates to the method used to obtain such a network and electrolyte.

Description

Detailed Description of the Invention

[0001] [Technical Field of the Invention] The present invention relates to a polymer electrolyte and a network formed by cross-linking the polymer electrolyte via an amine group of the polymer electrolyte. The network is designed as a multifunctional energy storage system capable of moving mobile cations through passages present in the structure of the network. The present invention also relates to a method for obtaining such a network and electrolyte.

[0002] [Background of the Invention] The invention of new energy storage materials has significantly contributed to the technological progress of applications such as aviation, portable electronic products, and electric vehicles. The improvement of the performance of energy storage systems has been achieved at the expense of the weight increase of structural members over the years. The emergence of multifunctional energy storage materials has brought about a large-scale and important opportunity for manufacturing lightweight and high-performance structures. "Multifunctional energy storage materials" refer to materials that simultaneously provide energy storage characteristics and endurance characteristics, thereby achieving weight reduction in energy storage applications that are easily affected by weight. The successful commercialization of multifunctional energy storage devices has not yet been achieved mainly due to the trade-off relationship between the energy storage capacity and mechanical properties such as endurance and structural integrity. The technology readiness level (TRL) of multifunctional energy storage devices is TRL4 - TRL5. Most research groups in related technical fields have focused on the development of different types of electrode materials and the improvement of specific capacitance values and specific surface area values to overcome this trade-off problem. Although improvements are seen in this regard, the low performance of the devices emphasizes the urgent need to improve the performance of other components such as electrolytes, separators, and their interfaces. What is urgently required in applications related to energy storage materials is the improvement of output density, which is directly related to the improvement of the ionic conductivity of the electrolytes used. In most structural applications where epoxy systems are used, the design of multifunctional resins that function as both electrolytes and high-performance matrices is difficult due to the trade-off between mechanical performance and ionic conductivity. The former requires an acceptable degree of mechanical rigidity and intact microstructure of polymer chain segments, while the latter requires soft chain segments and interconnected channels throughout the epoxy network. The two epoxy resins most commonly used in the production of multifunctional electrolytes are poly(ethylene glycol) diglycidyl ether (PEGDGE) and diglycidyl ether of bisphenol-A (DGEBA). In solvent-free polymer electrolytes, long-distance ion conduction is enabled by local polymer motion. A polymer matrix with a low degree of rigidity (robustness) usually results in higher conductivity.The incorporation of ionic liquids (ILs) into a matrix and the addition of some amount of lithium salts have been found to be effective means to promote ion transport (Shirshova et al., J. Mater. Chem. A 1 (2013) 15300 - 15309, DOI: 10.1039 / c3ta13163g; Jang et al., Macromol. Chem. Phys. 219 (2018), DOI: 10.1002 / macp.201700514; Baskoro and Yen, ACS Appl. Energy Mater. 2 (2019) 3937 - 3971, DOI: 10.1021 / acsaem.9b00295). ILs are widely used in polymer electrolytes due to their unique properties such as excellent thermal and chemical stability, low vapor pressure, non-flammability, low melting point, and high ionic conductivity.

[0003] As described by Shirshova et al. (J. Mater. Chem. A 1 (2013) 15300 - 15309, DOI: 10.1039 / c3ta13163g), the presence of ILs as molten salts within an epoxy network forms a co-continuous phase, which promotes ion migration. However, the matrix becomes soft as a result of the increasing amount of ILs, and sufficient structural properties (i.e., mechanical performance) cannot be obtained. In this regard, ILs and epoxy form a heterogeneous microstructure with insufficient ion transport due to the lack of an interconnected network (Shirshova et al. J. Phys. Chem. C 118 (2014) 28377 - 28387. doi: 10.1021 / jp507952b).

[0004] Another approach to simultaneously impart ionic conductivity and endurance is the copolymerization of specific types of unstructured monomers and structured monomers (Feng et al., Mater. Sci. Eng. B Solid-State Mater. Adv. Technol. 219 (2017) 37 - 44. doi:10.1016 / j.mseb.2017.03.001; DOI:10.1016 / j.mseb.2017.03.001). Among various unstructured polymer electrolytes, polyethylene oxide (PEO) has been considered the most promising polymer electrolyte because the distance between ether oxygen groups is appropriate (Westover et al., J. Mater. Chem. A. 3 (2015) 20097 - 20102. DOI:10.1039 / c5ta05922d). Since ion movement is easier in the amorphous regions of the polymer, several investigations have focused on reducing the crystallinity of PEO-based electrolytes by crosslinking, copolymerization, and addition of inorganic fillers (Kwon et al., ACS Appl. Mater. Interfaces. 10 (2018) 35108 - 35117, DOI:10.1021 / acsami.8b11016; Ji et al., Electrochim. Acta. 55 (2010) 9075 - 9082, DOI:10.1016 / j.electacta.2010.08.036). However, it should be noted that crosslinking binds both ends of the PEO chains, thereby significantly reducing the mobility of PEO (Snyder et al., Polymer. 50 (20), 4906 - 4916). Multifunctional plots are effective in interpreting the trade-off between the ionic conductivity and Young's modulus of structured electrolytes. The goal is to achieve values of ionic conductivity and Young's modulus higher than 0.1 mS / cm and 200 MPa, respectively, which are considered threshold values. A reasonable goal for structured electrolytes is to achieve both mechanical rigidity and ionic conductivity within an order of magnitude of the values of conventional materials. Figure 1 shows the degree of multifunctionality achieved in several publications.(Shirshova et al., J. Mater. Chem. A 1 (2013) 15300-15309, DOI: 10.1039 / c3ta13163g; Shirshova et al., J. Phys. Chem. C 118 (2014) 28377-28387, DOI: 10.1021 / jp507952b; Ji et al., Electrochim. Acta 55 (2010) 9075-9082, DOI: 10.1016 / j.electacta.2010.08.036; Matsumoto and Endo, Macromolecules 42 (2009) 4580-4584, DOI: 10.1021 / ma900508q; Matsumoto and Endo, Macromolecules 41 (2008) 6981-6986, DOI: 10.1021 / ma801293j; Matsumoto and Endo, J. Polym. Sci. Part A Polym. Chem. 49 (2011) 1874-1880, DOI: 10.1002 / pola.24614; Yu, Y., Zhang, B., Wang, Y., Qi, G., Tian, F., Yang, J., Wang, S. 2016. "Co-continuous structural electrolytes based on ionic liquid, epoxy resin and organoclay: Effects of organoclay content", Materials and Design, 104, 126-133, DOI: 10.1016 / j.matdes.2016.05.004). Despite many attempts in this field as shown in Fig. 1, structural electrolytes are still far from achieving the desired multifunctionality. Therefore, the development of new materials and architectures is the key to improving the multifunctionality of structural electrolytes.

[0005] [Object of the Invention] The main object of the present invention is to overcome the drawbacks in the prior art.

[0006] Another object of the present invention is to provide a polymer electrolyte with an increased degree of multifunctionality.

[0007] A further object of the present invention is to obtain a network using this polymer electrolyte.

[0008] Yet another object of the present invention is to propose a low-cost method that enables the production or construction of such a network and polymer electrolyte.

[0009] [Summary of the Invention] The present invention proposes a network comprising a polyoxazoline (POZ) backbone crosslinked via its amine groups. The network formed by using the polymer electrolyte according to the present invention enables a high degree of multifunctionality. The present invention further proposes a method for obtaining such a network and polymer electrolyte.

[0010] The figures briefly described herein are only intended to provide a better understanding of the present invention and are not intended to define the context in which the scope is to be construed in the absence of protection or description. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0012] [Detailed Description of the Invention] The present invention will be described in detail below with reference to each of the above figures.

[0013] The present invention relates to a network formed by crosslinking of polyoxazoline (POZ)-based electrolytes. The secondary amine groups present on the polymer backbone react with an epoxy resin to obtain a network structure. Due to the secondary amine groups, there is no need to use another curing agent for the formation of the network structure.

[0014] The epoxy resin can be selected from the class having at least two epoxide groups, thereby enabling the formation of a crosslinked network structure. Various epoxy resins can be utilized for this purpose. As an example, diglycidyl ethers having different structures can react with the secondary amine groups of two adjacent POZ polymers to form a network structure. The size and structure of the selected epoxy resin determine the distance between two POZ polymers and the flexibility of the network structure. Thereby, both the distance between the ionic groups present on different POZ polymers, which forms a pathway for the cations to move, and thus the ionic conductivity are determined. A general structure of the network exemplifying the pathways throughout the network is shown in FIG. 2. A cross-section of the network between two crosslinking points along each POZ polymer backbone and two connection points of two adjacent POZ polymers is shown in FIG. 3. The distance between two crosslinking points is determined by the number of secondary amine groups present along the polymer backbone, and that number is determined by the composition of the polymer. The composition of the polymer is determined in hydrolysis and methylation steps where the modification can be precisely controlled. The distance between two connection points of two adjacent POZ polymers is determined by the size of the epoxy resin, and that size is determined by the size of the R 4 group between two distal oxirane groups shown in FIG. 3. The distance between adjacent POZ polymers can be increased by selecting a "long" R 4 group such as bisphenol a compared to a "short" R 4 group such as ethylene glycol.

[0015] The present invention provides anions (Y - ) and cations (X +Furthermore, a polymer electrolyte useful for encapsulating - (Y + ) and cation (X + ) are introduced using an ionic component (e.g., one or more ionic solvents). The presence of such an ionic component should facilitate the movement of Li + ions through the channels within the network. The POZ-based polymer has secondary and tertiary amine groups that can be used in protonated or non-protonated forms. These groups are preferably protonated to some extent to obtain quaternary ammonium and secondary amine groups along the polymer backbone, thereby having cationic groups and reacting to form a cross-linked network structure to obtain a polymer electrolyte. After cross-linking the polymer electrolyte with an epoxy resin, a network in which quaternary ammonium groups that form the main structure of the channels are dispersed is obtained. The movement of Li

[0016] ions is accelerated by both the formation of channels between the quaternary ammonium groups of the polymer within the network and the repulsive force between the cation and the quaternary ammonium group. The anion and cation can preferably be provided using one or more ionic solvents (abbreviated as XY) in the electrolyte. Since the positive charge in the quaternary ammonium cation is higher than that of the secondary or tertiary amine, the movement of lithium ions (Li + ) is accelerated in the presence of quaternary ammonium groups throughout the network. Figure 3 shows a portion between two cross-linking points of the network structure formed as a result of cross-linking the secondary amine groups of a polyoxazoline polymer having quaternary ammonium groups with an epoxy resin. Figure 4 shows a more specific example of the same network. The lithium salt is incorporated into the network alone or, if necessary, in combination with an ionic liquid (IL) during the cross-linking process. The use of an ionic liquid increases the mobility; thus, the ionic conductivity of the network increases. The IL used herein is selected by means of obtaining the same anion or a different anion as Y - and will affect the dissociation ability of the ionic groups present on the polymer backbone; thus, the solubility of the lithium salt.

[0017] The present invention further proposes a method for obtaining the network discussed above. The present invention includes the following sequential steps: i. Obtaining a polymer having an amide group by cationic ring-opening polymerization of a monomer of general formula 2-R'-2-oxazoline; ii. Hydrolyzing the polymer (polymer chain) obtained in step (i), thereby obtaining a POZ chain containing a secondary amine in addition to the amide group described in step (i); iii. Crosslinking the POZ chains via secondary amine groups, thereby obtaining a network of the POZ main chain is included.

[0018] In step (ii), the hydrolysis can be carried out using any method known in the art, for example, a method involving the use of a strong acid or a strong base.

[0019] Preferably, this method includes the following step (x1) between step (ii) and step (iii): (x1) Partially converting the secondary amine groups of the polymer obtained in step (ii) into quaternary ammonium groups by alkylation (e.g., methylation) and subsequent protonation, thereby obtaining a polyoxazoline (POZ) chain having a cationic group. Preferably, before step (iii), after step (x1), step (x2) defined below follows: (x2) Adding a cation (X + ) and an anion (Y - ) to the POZ chain obtained in step (x1), thereby obtaining a mixture thereof. The introduction of these ions can be achieved by using an ionic solvent (e.g., HPF 6 ). Thereby, the cation (X + ) and the anion (Y -can be quickly incorporated into the resulting network, eliminating the need to develop a process for introducing these ions after the formation of the network. In addition to the polymeric ionic liquid groups present within the network, many ILs or solvents (e.g., ethylene carbonate, propylene carbonate) containing various dissolved lithium salts can be included in the network during the crosslinking process to enhance mobility and ionic conductivity.

[0020] The "R 1 " group of the oxazoline monomer represents a linear, branched, or cyclic aliphatic or aromatic group. The type of R 1 affects the solubility of the monomer and the mechanical properties of the resulting network. Monomers containing aromatic R 1 groups (such as 2-phenyl-2-oxazoline) result in networks that are more rigid and have a higher T 1 (glass transition temperature) and lower ionic conductivity compared to networks made using monomers containing aliphatic R g groups (such as 2-ethyl-2-oxazoline). On the other hand, the use of oxazoline monomers with short alkyl chains, which have high compatibility with a wide variety of crosslinking agents, results in flexible network structures with sufficient mechanical strength and high ionic conductivity.

[0021] Considering the R 1 group of the monomer, aliphatic groups are more preferred among all the groups listed above due to their commercial availability, ease of synthesis, and feasibility. The linear aliphatic group can be selected from alkyl chains having 1 to 22 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 3 carbon atoms, which are methyl-, ethyl-, and propyl- groups. Thus, 2-R 1-2-Oxazoline corresponds to 2-alkyl-2-oxazoline that can be selected from 2-methyl-2-oxazoline, 2-ethyl-2-oxazoline, 2-propyl-2-oxazoline, or a mixture thereof. These monomers are highly preferred because they are easy to synthesize, inexpensive, and commercially available. The degree of hydrophobicity of the monomers increases as the length of the alkyl chain increases. The compatibility of 2-ethyl-2-oxazoline is very good with both polar solvents (such as water) and nonpolar solvents. Therefore, 2-ethyl-2-oxazoline is the most preferred monomer in the present invention.

[0022] Figure 5 shows an exemplary variation of the method according to the present invention and includes steps (i), (ii), (x1), (x2) and subsequently (iii). In the example of step (i) shown in Figure 5, triflic acid is used as the initiator and 2-ethyl-2-oxazoline is used as the 2-alkyl-2-oxazoline monomer. Other known initiators can be used instead of or together with triflic acid. In step (i), the cationic ring-opening polymerization is preferably allowed to proceed until the number (x) of repeating units reaches a range of 2 to 1000, more preferably 10 to 100, and even more preferably 10 to 50.

[0023] In step (ii), the degree of hydrolysis can preferably be arranged such that the ratio of the number (n) of amide groups to the number (k) of secondary amines is in the range of 100:1 to 1:100, more preferably 9:1 to 1:9. This criterion can be applied by those skilled in the art of polymer synthesis without undue burden. Increasing the (n) / (k) ratio correspondingly: The number of crosslinkable secondary amines along the POZ main chain decreases, resulting in a decrease in the rigidity of the network, The distance between crosslinking points along the POZ main chain increases, which promotes the flexibility of the network during crosslinking, and thus the possibility of cation movement through the channels throughout the formed network and the conductivity of the network increase, The generation of secondary or tertiary amine groups, as obtained in step (x1), is reduced, thereby affecting the number of crosslinking sites, as well as the number of cationic groups present in the polyoxazoline-based electrolyte, and the resulting network.

[0024] In step (ii), some of the amide groups on the polymer chain are hydrolyzed to form secondary amine groups. The molar ratio of amide groups to secondary amines (i.e., the n / k ratio discussed above) can be arranged by those skilled in organic chemistry, without undue burden, by controlling the degree of hydrolysis. The secondary amines in a predetermined portion of the resulting polymer may be methylated. Subsequently, quaternization is carried out using an ionic solvent (XY) in step (x1) to obtain quaternary ammonium groups on the POZ backbone that act as polymer-bound ionic components. These ionic components will provide a medium for the lithium salt to dissolve. The presence of ionic components on the polymer allows for the network to contain no additional ionic liquid and / or other solvents, or to contain them in a lesser amount if they are included. The adverse effects on the mechanical properties by including such molecules (ionic liquid and / or other solvents) in the network are thus limited by this means. These ionic components will also create ionic pathways for the lithium ions to move throughout the network, which is shown in Figure 2.

[0025] The ionic conductivity of the electrolyte can be improved by an appropriate selection of the ionic component (XY). Anions (Y - ) with highly delocalized negative charges promote the movement of Li + ions along the channels in the network, thereby promoting the solvation of Li + ions in the network and thus increasing the conductivity of each polymer-based electrolyte.

[0026] The selection of the lithium salt can be made considering the dissociation constant (Kd) and / or the volume bulkiness of each anion. Y -Since the anions are not covalently bonded to the network, Y - the anions will also move within the network. However, by selecting relatively large anions, the movement of the anions should be considerably restricted. Although relatively large anions also contribute to ionic conductivity, the movement of such anions will also cause polarization, thereby shortening the life of the electrolyte. Li + If the cations are the only components contributing to ionic conduction, it can be considered a single-ion conductive solid electrolyte.

[0027] The increase in the Kd value (sufficiently delocalized charge and low basicity) essentially corresponds to the increase in the difference between the volume bulkiness of each anion (Y - ) and Li + cation in each lithium salt structure, and is thus preferable. When comparing various lithium salts (i.e., LiPF 6 , LiClO 4 , LiBF 4 , LiTFSI, LiTf, LiFSI), when the bulkiness of the anion is large, the dissociation of Li + ions is promoted, and its movement through the channels along the network is promoted, thereby increasing the conductivity of each polymer-based electrolyte.

[0028] Considering the main effect of the above (n) / (k) ratio, when the ratio is within the range of 9:1 to 1:9, a high degree of rigidity is guaranteed along with a sufficient degree of ionic conductivity. More preferably, the ratio of (n) / (k) is within the range of 3:1 to 1:3. This range corresponds to the sweet spot that enables an acceptable degree of rigidity and conductivity simultaneously.

[0029] In step (iii), the cross-linking of the POZ chains is carried out through the reaction of the secondary amine groups of the polymer and the epoxy resin to form a mechanically and ionically conductive interconnected polymer network. The presence of secondary amines on the POZ main chain eliminates the need to use any additional curing agents. R 1 and R4 The final mechanical properties, viscosity, crystallinity, and cation mobility are determined by the chemical structure of the base.

[0030] Polyoxazoline (POZ) as the main chain achieves a mechanically strong ion-conductive polymer. POZ is considered a suitable and even more advantageous alternative to poly(ethylene oxide) (PEO / PEG) polymers and is widely used as a solid electrolyte in energy storage devices. The multifunctional network of POZ enables the attachment of several chemical groups to a single polymer backbone, thereby improving the structural multifunctionality. For the first time in the literature, ion-conductive POZ-based polymers will be utilized as "multifunctional electrolytes" by incorporating ionic component(s) into the backbone of the POZ polymer. Confining the ionic component(s) within the POZ backbone enables 1) controlling the path of ions at the molecular scale and improving the lithium ion transport rate, and 2) solving the two-phase problem in the structural electrolyte. Along with other characteristics used in the formation of polymer electrolytes, the multifunctionality of POZ results in a highly ion-conductive network with sufficient mechanical performance, i.e., both the conductivity and Young's modulus values are within the range of the target multifunctional region shown in Figure 1. To provide rigidity, various cross-linking agents such as various diglycidyl ethers can be attached to the backbone of POZ. It is also possible to replace POZ with various multifunctional polymers using the manufacturing methods and methodologies described herein.

[0031] Inorganic nanofillers such as silica (SiO 2 ), titanium dioxide (TiO 2 ), or halloysite nanotubes (HNT) can be used to increase the degree of amorphousness of the network and further improve the ion transport ability within the polymer electrolyte.

[0032] As a means of determining the geometry / contour of the network, before crosslinking, POZ can be cast using a robust (e.g., self-supporting) polymer film and a thin separator made of a veil to prepare an ion-conductive prepreg. This exemplary means is applicable to the preparation of various types of multifunctional energy storage devices such as wearable / flexible supercapacitors, structural supercapacitors, and lithium-ion batteries using the network according to the present application.

[0033] Therefore, according to the present invention, at least the following advantages can be made available: As mentioned in the background section, due to the trade-off between ion conductivity and mechanical performance, the currently used electrolyte systems degrade the mechanical performance of the final composite product. The present invention proposes a polymer network by precise design of the functional groups, molecular weight, and morphology of the synthesized polymer, thereby improving the electrolyte properties without significantly reducing the mechanical performance of the final composite product compared to pure resin systems.

[0034] Polyoxazoline (POZ) has been used as a favorable alternative to known polymer electrolytes. The multifunctional network of POZ facilitates the design and formulation of polymer-based electrolytes with desired characteristics. Since various crosslinking agents (e.g., various diglycidyl ethers such as ethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether) can be bonded, the rigidity and ion conductivity can be easily adjusted.

[0035] The secondary amine groups in POZ act as curing agents, eliminating the need to include additional curing agents during network formation.

[0036] In the background art, the combination of IL and PEG results in a decrease in processability to accelerate the curing time of the polymer. In contrast to PEG, POZ has a low viscosity, thereby promoting processability, but the use of IL and solvents is lacking or minimized during the network formation process, reducing the possibility of any problems related to processability such as acceleration of curing.

[0037] The multifunctional network of POZ improves the control over various parameters such as molecular weight, chain length, distance between consecutive functional groups, and crosslink density, resulting in the formation of a uniform and interconnected network with improved ion transport and mechanical performance.

[0038] The proposed POZ-based electrolyte can be incorporated into various structural energy storage systems such as structural supercapacitors, structural lithium-ion batteries, flexible electronics, and wearable electronics.

[0039] The present invention is expected to open up new opportunities particularly in the field of multifunctional polymer composites and enable the expansion of the technology readiness level (TRL) of structural energy storage devices.

[0040] The following examples are based on proof-of-concept experiments in the context of this application. Specific features such as the chain lengths and functional groups described or referred to should be considered merely as examples of their possible variants within the scope of the independent claims.

[0041] (Example) An experimental study is conducted to demonstrate that the proposed technology establishes an alternative to conventional multifunctional electrolyte systems. An exemplary route for obtaining a polymer-based electrolyte is shown in FIG. 5. FIG. 5 shows the synthesis of an exemplary POZ-based polymer, an exemplary polymer-based electrolyte, and an exemplary network. The steps shown in FIG. 5 are: (i) attempting the ring-opening polymerization of 2-ethyl-2-oxazoline in the presence of triflic acid as initiators with different molecular weights (Mw) of 1 kDa, 2 kDa, and 5 kDa, each of these options having been proven to function fully, (ii) hydrolysis of the synthetic polymer to form secondary amine groups, (x1) methylation and (x2) introduction of ionic components, (iii) reacting the secondary amine groups of the POZ polymer with different epoxy resins to form a network structure, representing an example of the steps.

[0042] In this experimental example, POZ is synthesized by ring-opening polymerization of 2-ethyl-2-oxazoline as a monomer and triflic acid as an initiator (Figure 5, step (i)). Different types of monomers such as 2-methyl-2-oxazoline and 2-propyl-2-oxazoline can also be used for the synthesis of POZ polymers. A typical procedure for the ring-opening polymerization of poly(2-oxazoline) is used, which is described by Viegas et al. (Bioconjugate Chem. 2011, 22, 5, 976-986, DOI: 10.1021 / bc200049d).

[0043] In the case of ring-opening polymerization (step (i)), first, a mixture containing the monomer and the initiator is prepared. The molecular weight (MW) of the resulting polymer chain can be easily determined in advance by adjusting the molar ratio of the monomer (M 0 ) and the initiator (I 0 ). As can be inferred by those skilled in the art of organic synthesis, a wide range of molecular weights can be synthesized by changing the process parameters using the knowledge of the prior art. The mixture is heated in a reactor to a temperature within a range of, for example, 60 °C to 90 °C, depending on the desired MW. To stop the polymerization, the contents of the reactor are cooled and mixed with a terminator containing a terminal, for example, hydroxyl or carboxylic acid.

[0044] The quaternary ammonium group can be considered as a site for imparting the characteristics of ionic liquids to the electrolyte according to the present invention.

[0045] (Reference numerals) R1 Side group bonded to the oxazoline ring in the oxazoline monomer R2 Hydrogen atom, methyl or another alkyl group in the POZ chain R3 Hydrogen atom R4 Portion of the epoxy resin that binds two distal ends (diglycidyl ether) X + Cation of the ionic component present on the POZ main chain Y - Anion of the ionic component present on the POZ main chain The sum of k, l and m (the number of repeating units having a secondary amine group after the hydrolysis step) l The number of repeating units of POZ having a secondary amine group m The number of repeating units of POZ having a quaternary ammonium group x The number of repeating units of the POZ polymer

Claims

1. The following formula: 【Chemistry 1】 [R ２ is a methyl group, R ３ is a hydrogen atom, and Y － is a corresponding anion], wherein the polyoxazoline-based electrolyte further comprises a secondary amino group as a cross-linking site for forming a network including the polyoxazoline-based electrolyte cross-linked with the epoxy resin via the secondary amino group of the polyoxazoline-based electrolyte upon reaction with an epoxy resin.

2. 2. A network formed by crosslinking the polyoxazoline electrolyte of claim 1, wherein the polyoxazoline electrolyte is crosslinked with an epoxy resin via the secondary amino groups of the polyoxazoline electrolyte such that the groups represented by the above formula of the polyoxazoline electrolyte are dispersed in the network.

3. Dispersed formula: 【Chemistry 2】 [R ２ is a methyl group, R ３ is a hydrogen atom, and Y － is the corresponding anion, which comprises the following subsequent steps: i.2-R １ -2-oxazoline [R １ is selected from the list consisting of linear, branched and cyclic aliphatic groups and aromatic groups, to obtain a polyoxazoline polymer having amide groups; ii. hydrolyzing the polyoxazoline polymer obtained in step (i), thereby obtaining polyoxazoline chains containing secondary amino groups in addition to the amide groups mentioned in step (i); (x1) partially converting the secondary amino groups into tertiary amine groups, thereby obtaining a polyoxazoline chain having a tertiary amine group; (x2) Protonation of the tertiary amine groups with one or more ionic components (XY) to generate the corresponding anions (Y － ) to form a polyoxazoline-based electrolyte containing the group represented by the above formula and a secondary amino group as a cross-linking site for forming the network; iii. Crosslinking the polyoxazoline chains with an epoxy resin via their secondary amino groups, thereby obtaining the network; A method comprising:

4. 4. The method of claim 3, wherein step (x2) is followed by the introduction of one or more ionic liquids (ILs) and / or one or more organic solvents having dissolved therein one or more lithium salts.

5. The R １ The method of claim 3 or 4, wherein is selected from methyl, ethyl or propyl, whereby said monomers include 2-methyl-2-oxazoline, 2-ethyl-2-oxazoline, or 2-propyl-2-oxazoline, or mixtures thereof.

6. The method of claim 5, wherein the monomer is 2-ethyl-2-oxazoline.

7. 7. The method of any one of claims 3 to 6, wherein the cross-linking in step (iii) comprises the use of a diglycidyl ether as a cross-linking agent.

8. 8. The method of claim 7, wherein the crosslinking agent is selected from the list consisting of ethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, or a mixture thereof.

9. 9. The method of any one of claims 3 to 8, wherein in step (i), the ring-opening polymerization is allowed to proceed until the number of repeat units (x) of the polymer is in the range of from 2 to 1000.

10. 10. The method according to any one of claims 3 to 9, wherein in step (ii) the degree of hydrolysis is arranged such that the ratio of the number of amide groups (n) to the number of secondary amines (k) is in the range of 100:1 to 1:100.

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