Improved synthesis method for producing regular polyblock copolymers with a controllable molecular weight distribution

Abstract

The present invention relates to a method for the sequential and convergent preparation of regular block copolymers comprising at least one nonpolar and one polar polymer block, wherein the nonpolar block is constructed from specific monomers via sequential living anionic polymerization with a Li organyl initiator having a pKa of 45 or greater, the polar block is constructed from a monomer having a molecular weight of 350 g / mol or greater and 5000 g / mol or less and selected from the group consisting of C2-C10 oxacyclo compounds, their derivatives, or a mixture of at least two different monomers thereof, and the polar polymer block is covalently bonded to the nonpolar block anion in a single step via epoxy functionalization of one of the monomers obtained via reaction of the polar block monomer with epichlorohydrin in a nonpolar solvent in the presence of free Li ions. Furthermore, the present invention relates to specific block copolymers with short polar chains of very uniform chain length, polymer electrolytes, and the use of the block copolymers as polymer electrolytes in secondary alkaline batteries.

Description

[Technical Field]

[0001] The present invention relates to a method for the sequential and convergent preparation of a regular block copolymer comprising at least one nonpolar and one polar polymer block, wherein the nonpolar block is constructed from a specific monomer via sequential living anionic polymerization with a Li organyl initiator having a pKa of 45 or more, and the polar block is a polymer block constructed from a monomer selected from the group consisting of C2-C10 oxacyclo compounds, their derivatives, or mixtures of at least two different monomers having a molecular weight of 350 g / mol or more and 5000 g / mol or less, wherein the polar polymer block is covalently bonded to a nonpolar block anion in a single step via one epoxy functionalization of the monomer, obtained by the reaction of the monomer of the polar block with epichlorohydrin in a nonpolar solvent in the presence of free Li ions. Furthermore, the present invention relates to the use of a specific block copolymer, polymer electrolyte, and block copolymer having short polar chains with very uniform chain lengths as a polymer electrolyte in secondary alkaline batteries. [Background technology]

[0002] One of the prerequisites for the success of advancements in portable electrical devices has been the provision of a sufficiently large and safe energy source, particularly in the form of alkaline rechargeable batteries, which contribute to unimaginable flexibility and usable life under everyday conditions. However, application safety remains a starting point for further development today, especially since solvent-based liquid electrolytes sometimes pose a higher risk in terms of flammability. For this reason, thorough research is being conducted on alternative electrolytes that do not, in principle, pose these risks.

[0003] Solid electrolytes, such as polymer electrolytes based on polyethylene oxide (PEO) polymers and lithium conductive salts, have been studied since the 1970s and form a solvent-free class. These are safe to use and are commercially traded as so-called lithium polymer cells. Current developments are increasing the share of polymer electrolyte cells in demanding and energy-intensive application areas such as electromobility. A disadvantage of PEO-based polymer electrolytes is that they can generally only be used at temperatures above their melting point (approximately 60°C) without sacrificing performance, because only at that temperature do they possess sufficient conductivity for battery applications. Other possible polymer electrolytes, such as polycarbonate, can also only be processed above their glass transition temperature, and even then, they exhibit rather low ionic conductivity for modern high-performance batteries. Furthermore, when using these polymers, lithium ion conductivity cannot be controlled independently of mechanical stability, which is fundamentally important for suppressing lithium dendrite growth at the lithium metal anode.

[0004] The starting point for separating the mechanical and ionic conductivity properties of polymer electrolytes was identified in the regions that construct the regular micro- and nanostructures of ionic conductivity domains. By using block copolymers (BCPs) with different but regular block domains, electrochemical and mechanical properties can be tuned separately. Due to the interaction of polymer segments of individual block polymers, they self-assemble, forming a regular network of ionic conductivity domains where high migration numbers exist simultaneously with continuously separated and rapid lithium ion conduction. However, a prerequisite for the formation of highly organized macroscopic domains is that the block copolymers used have highly reproducible properties.

[0005] Some methods for determining the structure and ionic conductivity of polymer electrolytes derived from block copolymers can also be found in the literature.

[0006] For example, Dorr et al., in Chem.Eur.J.2018, 24, 8061-8065 (DOI:10.1002 / chem.201801521), "An Ambient Temperature Electrolyte with Superior Lithium Ion Conductivity based on a Self-Assembled Block Copolymer," described the possible configurations and properties of block copolymers for use as polymer electrolytes.

[0007] US2012 / 0264880A1 discloses a method for synthesizing block copolymers that exhibit both electronic and ionic conductivity. A combination of Grignard metathesis polymerization and click reactions is used sequentially to synthesize block copolymers from poly(3-hexylthiophene)(P3HT) and poly(ethylene oxide).

[0008] Furthermore, US7715922B1 discloses an implantable medical device formed from a polymer material comprising, at least in part, a base polymer and a block copolymer. The block copolymer comprises at least one polyethylene oxide (PEO) block and at least one polyisobutylene (PIB) block. The PEO and PIB blocks may be coupled together by a urethane or urea bond. The block copolymer may be a triblock copolymer, PEO-PIB-PEO, and the base polymer may be a polystyrene-polyisobutylene-polystyrene triblock copolymer.

[0009] Such solutions known from the prior art may have room for further improvement, particularly in terms of the simplicity, safety, scalability, and efficiency of synthesis, as well as the reproducibility of the block copolymers that can be obtained through synthesis. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Therefore, the object of the present invention is to overcome, at least partially, the disadvantages known from the prior art. In particular, the object of the present invention is to propose an easily scalable synthetic route that can be easily and inexpensively implemented, yields high yields, and results in a regular block copolymer having a tunable, defined structure and molecular weight of individual blocks. [Means for solving the problem]

[0011] This problem is solved by the features of each independent claim directed toward the use of the block copolymer as a polymer electrolyte in secondary alkaline-ion batteries, the method according to the present invention, the block copolymer that can be obtained through the method according to the present invention, the polymer electrolyte containing the block copolymer, and the use of the block copolymer thus obtained as a polymer electrolyte in secondary alkaline-ion batteries. Unless the context makes otherwise clear, preferred embodiments of the present invention are described in the dependent claims, specification or drawings, and further features described or shown in the dependent claims or specification or drawings, individually or in any combination, constitute the subject matter of the present invention. [Modes for carrying out the invention]

[0012] According to the present invention, the problem is solved by a method for the sequential and convergent preparation of a regular block copolymer comprising at least one nonpolar and one polar polymer block, wherein the nonpolar block is constructed from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinyl metallocene, derivatives thereof, or mixtures thereof via sequential living anionic polymerization with a Li organyl initiator having a pKa value of 45 or more, and the polar block is a polymer block comprising monomers selected from the group consisting of C2-C10 oxacyclo compounds, derivatives thereof, or mixtures of at least two different monomers having a molecular weight of 350 g / mol or more and 5000 g / mol or less, wherein the polar polymer block is covalently bonded to the nonpolar block anion in a single step via one epoxy functionalization of the monomer obtained by the reaction of the monomer of the polar block with epichlorohydrin in a nonpolar solvent in the presence of free Li ions.

[0013] Remarkably, BCPs with two or more different nonpolar / polar blocks can be obtained through the method outlined above, from which it has been found that they exhibit a reproducible and uniform distribution of chain lengths, particularly of individual polymer blocks. This method allows for the determination of the exact number of monomers for each polymer block within a very narrow distribution limit, independent of the chemical properties of the monomers used in the individual blocks. The polydispersity index (PDI) of the block copolymer as a whole, and especially of the short polar blocks, can be less than 1.04. Block copolymers that are difficult to synthesize by other methods can be flexibly obtained, and these block copolymers cannot be produced at all or efficiently by conventional methods. In particular, highly asymmetric BCPs can be synthesized with less effort, characterized by differences in strongly different block lengths, strongly different polarities, or even both. Self-assembling, highly structured BCPs are readily available through improved structures with more uniform chain lengths of the copolymer as a whole and, in each case, for individual blocks, and these block copolymers can simultaneously exhibit both good mechanical properties and, if desired, controlled ionic conductivity properties. For example, BCPs can consist of defined ion-conducting segments, such as polymer segments, which exhibit isolated lithium-ion motion and therefore rapid lithium-ion transport. In particular, this can be achieved by polar blocks that are very equal to and very short compared to non-polar blocks, resulting in a larger deviation in the monomer number of the constructed polar blocks compared to standard procedures. The improved uniformity of the monomer number of polar blocks allows multiple polymers to fuse into defined, highly regular domains, resulting in improved alkali ion conduction across the domains. By using BCPs with different monomers and chain lengths, functionalities can be selectively separated and individually optimized. In contrast to conventional techniques, there is another advantage that comes from the fact that synthesis can be easily scaled to mass production and generally automated, as it does not require solvents or counterion exchange, toxic gases, and additional additives or catalysts.Furthermore, through the coupling of the polar blocks according to the invention via specific functionalizations, very homogeneous polar blocks can be produced by functionalizations that essentially have the same or similar chemical properties as the monomers of the polar blocks. This can lead to a particularly uniform structure of the polar blocks, including their coupling to the nonpolar blocks.

[0014] The reaction process can be exemplified, for example, by the following scheme:

[0015]

Chemical formula

[0016] One or more nonpolar blocks A and B are constructed via sequential living anion polymerization (steps a)+b)). It is also possible to construct only one nonpolar block in this way. A third polar block (C), functionalized via an epoxy group, is then covalently added once in a convergent manner to this nonpolar anion block (step c is the convergent step). The epoxy functionalization of the polar block (C) can be obtained, for example, via a simple reaction of the polar block (C) with epichlorohydrin (step d). A negatively charged polar / nonpolar block copolymer is obtained, which due to the association of lithium to the negatively charged oxygen of the open epoxide group, does not allow for further addition reactions. Thus, block C is added exactly once. In the absence of lithium, or if lithium is not coordinated or not sufficiently firmly coordinated to the negatively charged oxygen atom, further reactions can occur, and as a result, the molecular weight of the resulting BCP can vary significantly.

[0017] The method according to the present invention may be particularly suitable for constructing BCPs having different polarity blocks or block lengths. According to the prior art, polar regular BCP systems, such as ion-conducting polymer blocks, have so far been constructed only from each monomer in a continuous switching sequence of polymerization steps based on the basic principle of sequential living anion polymerization. This method requires the sequential application of two different polymerization mechanisms. In particular, polar blocks can be formed only via living anion ring-opening polymerization. Nonpolar monomers are polymerized by anions via carbanions, followed by polar blocks via ring-opening polymerization of oxygen anions, which, after exchange of solvent and counterions, form open epoxy rings.

[0018] For example, during conventional BCP synthesis from monomers (ethylene oxide gas), a complex two-step synthesis process is required to construct lithium-ion conductive domains based on polar PEO blocks:

[0019] [ka]

[0020] In the first step, a defined polymer block is constructed from nonpolar monomers via living anionic polymerization (step a). At the end of this step, a polymer anion containing lithium as a counterion is present. A complex exchange of lithium with potassium is required to bond polar ethylene oxide, for example, to this anionic polymer block, because further reactions of ethylene oxide, for example, are excluded due to the stronger association of lithium with the anion (steps b and c). Only after cation exchange and solvent exchange can the ethylene oxide bond to the block polymer anion via further living (ring-opening) polymerization (step d). Thus, the defined organization of polarity to nonpolar blocks for preparing, for example, ion-conducting di, triblocks and higher-grade multi-BCPs becomes complicated and expensive. This is in contrast to the preparation according to the present invention presented above, in which BCPs for the intended polymer electrolyte can be synthesized, thereby eliminating the need for the use of toxic and highly explosive ethylene oxide gas, and polar blocks are convergently bonded to the ends of nonpolar anionic polymer blocks. In addition, it is also an advantage that very short polar blocks can be reproducibly bonded via the method according to the present invention.

[0021] The method according to the present invention is a method for the sequential and convergent preparation of a regular block copolymer comprising at least one nonpolar and one polar polymer block. The method according to the present invention yields a copolymer, which is a polymer consisting of at least two distinct monomer units. The distinct monomer units are not randomly arranged within the polymer chain. The reactive monomer units are located in different regions of the polymer chain. This results in the acquisition of individual blocks of different polymers. According to the present invention, the organization of the polymer chain is carried out sequentially and convergently, meaning that the production of the BCP is carried out not within a single production step, but by at least two distinct downstream steps, although the production is carried out as a "one-pot" reaction within the same reaction environment. Bonding is carried out convergently by a single reaction of the terminal functionalizing monomers of the polar block. The downstream production steps then each include the organization of a single block of the BCP. It is also possible to obtain a single block via polymerization of individual monomers rather than the whole. Furthermore, a regular BCP can be obtained through this method. In this context, "regular" means that a copolymer is obtained in which it is essentially possible to align at least a portion of polymer blocks, e.g., polar blocks, in a semi-crystalline or crystalline structure. Thus, polymers can form a regular structure defined within themselves, at least over a certain subrange. The regular structure can be detected, for example, by X-ray scattering. The number of different blocks forming a BCP is not fundamentally limited. It is advantageous for a BCP to have at least two, preferably at least three, different monomer units in it. The maximum number of different blocks may be less than 10, preferably less than 8, and even more preferably less than 5. In this context, the terms "non-polar" and "polar" refer to the polarity of individual monomers, and therefore the polarity of the chain segments or blocks produced therefrom. Polar blocks are obtained from polar monomers that contain heteroatoms, e.g., oxygen or nitrogen. Halogens are excluded from heteroatoms. Non-polar monomers or blocks include monomers that are essentially hydrocarbons and do not contain heteroatoms, e.g., boron, oxygen, nitrogen, sulfur, phosphorus, or halogens.Examples of nonpolar monomers include conjugated dienes, styrene, vinylnaphthalene, vinyl metallocene, and vinylsilane.

[0022] Nonpolar blocks are constructed from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, their derivatives, or mixtures thereof, via sequential living anionic polymerization with a Li organyl initiator having a pKa value of 45 or greater. It has been found particularly advantageous that at least one polymer block is obtained via living anionic polymerization in order to construct a regular BCP. Living polymerization is understood as a chain polymerization in which no terminal reactions or chain transfers occur, and monomers are added to an already formed anionic chain structure via nucleophilic attack of the resulting carbanion. Therefore, different blocks can only be bonded in descending order of the pKa values ​​of their monomers. Under "living conditions," control of molecular mass in a very narrow distribution becomes possible. Furthermore, clearly defined polymer structures, e.g., BCPs with fixed sequence lengths, can be produced under these conditions. One possibility of this type of method control will be demonstrated later in the examples. Nonpolar blocks consist of nonpolar monomers, and the shown group of monomers throughout the block polymer can contribute to the formation of improved mechanical properties. In addition, surprisingly, these monomers have also been found to positively influence the crystallization behavior and the properties of the polar blocks described below. Without being bound by theory, structures achievable through polar blocks by the addition of several nonpolar blocks to each other also appear to be influenced and controlled through one framework function of the nonpolar blocks. In particular, combinations of selections from the group of nonpolar monomers mentioned above can result in particularly regular BCPs in the methods according to the present invention. Nonpolar monomers can be readily converted into nonpolar defined polymer blocks by living anionic polymerization. These derivatives are understood to be monosubstituted or polysubstituted conjugated dienes, styrene, vinylnaphtalines, vinyl metallocenes, and vinylsilanes, whose substituents may consist of linear and / or branched alkyl and / or alkoxy chains having chain lengths of C1 to C10. The conjugated dienes may be, for example, butadiene, isoprene, or methylisoprene.Styrene derivatives are understood to be derivatives of styrene, 4-methylstyrene, 4-(1-adamantyl)-alpha-methylstyrene, 3-(dimethylisopropylsiloxyl)-styrene, etc. Vinyl metallocenes may be, for example, vinylferrocene, vinylcobaltocene, vinylmanganosene, or vinylnickerosene. Possible Li organyl initiators include at least lithium and an organic radical, the organic radical may be aliphatic or aromatic. For example, the following Li organyl initiators may be used in the method according to the present invention: alkyllithium, e.g., methyllithium, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, pentyllithium, isopentyllithium, or neopentyllithium. Examples of aromatic lithium organyl initiators include phenyllithium or naphthyllithium. The corresponding pKa values ​​of the initiators can be found in the literature.

[0023] The polar block is a polymer block having a molecular weight of 350 g / mol or more and 5000 g / mol or less, and consists of monomers selected from the group consisting of C2-C10 oxacyclic compounds or mixtures of at least two different monomers. In particular, the method according to the present invention can be used to bond very defined polar monomer blocks from the group mentioned above. Thereafter, the proposed synthesis results in a very homogeneous block copolymer having an extremely homogeneous molecular weight distribution. In particular, this can lead to the conclusion that this very homogeneous molecular weight distribution of the block polymer is particularly suitable for the composition of polymer electrolytes. According to the present invention, rather than individual monomers, relatively short polar chains are convergently bonded to nonpolar block anions in a single step. Examples of C2-C10 oxacyclo compounds include ethylene oxide, propylene oxide, and butylene oxide. Preferably, C2-C4 oxacyclo compounds can be used in particular to construct polar blocks. Derivatives of C2-C10 oxacyclo compounds are understood to consist of one or more substituents, which may consist of linear and / or branched alkyl and / or alkoxy chains having a chain length of C1-C10.

[0024] The polar polymer block is obtained by the reaction of the monomer of the polar block with epichlorohydrin in a nonpolar solvent in the presence of free Li ions, and is covalently bonded to the nonpolar block anion in a single step via one epoxy functionalization of the monomer of this polar block. Bonding of the polar polymer block occurs via at least one chemical functionalization of the monomer of the polar polymer block chain, and then bonding of the nonpolar block to the polymer anion occurs via this functionalization. Epichlorohydrin reacts with the monomer of the polar block via a chlorine-functionalized C atom, leaving the epoxide group of the polar block. This epoxy-terminated functionalized polar polymer block is capable of forming a single covalent bond with the polymer anion in the anionic polymerization reaction environment. In this regard, the polar polymer block before the reaction consists only of the polar chain and further functionally bonded epoxy groups. Functionalization of the polar block is carried out outside the reaction solution of the anionic polymerization. In the preparation method according to the present invention, since this is a convergent synthesis, only the functionalized polar block is added to the anionic polymerization solution. Thus, the functionalized polar block is added to the anionic polymerization solution. Depending on the choice of functionalization bond, polar polymer blocks can have more or less consistent chemical and physical properties. When chemical functionalization is carried out using epichlorohydrin, chemical properties similar to those of the monomers of the polar block are obtained through the resulting epoxy functionality. Bonding of polar polymer blocks can be carried out without significant interference to the polar polymer structure due to the highly homogeneous properties of the functionalized polar block. The latter can result in an improved crystalline structure, especially when several block copolymers are thus combined to form a regular structure, either as is or in partial regions. The reaction is always carried out in a nonpolar solvent in the presence of free lithium ions. Free lithium ions are ions that can coordinate polarly / nonpolarly to the negatively charged oxygen at the binding site and thus prevent further reactions at the negatively charged oxygen. Non-"free" lithium ions exist, for example, as insoluble lithium salts, e.g., LiF, LiCl, or bond to other parts of the block copolymer.These lithium ions cannot interact with negatively charged oxygen due to coordination fixed at other sites, and therefore, undesirable additional addition steps cannot be prevented. The nonpolar solvent is a solvent selected from the group of aromatic hydrocarbons that do not contain heteroatoms. Possible nonpolar solvents may be, for example, benzene, toluene, xylene, mesitylene or other single or multiple alkyl-substituted derivatives, or a mixture of at least two solvents from this group.

[0025] In a preferred embodiment of this method, the polar block may be a polyethylene oxide block. The method according to the present invention has proven particularly advantageous when very short polar polymer blocks must be bonded to larger non-polar polymer blocks. This embodiment is very difficult to implement using prior art methods (see above) because consistent control and tracking of conversions at very short chain lengths is extremely difficult to perform analytically. Furthermore, the very short polymer chain lengths of polar polymer blocks mean that even small disruptions in synthesis immediately result in large relative deviations of the composition. In this regard, it is precisely in these synthetic situations that the method according to the present invention can contribute to individual BCP compositions that are nevertheless significantly more reproducible. In particular, the method according to the present invention can be used to bond very defined polar ethylene oxide blocks. Thereafter, the proposed synthesis method yields a very homogeneous block copolymer with an extremely homogeneous molecular weight distribution. In particular, this can lead to the conclusion that this extremely homogeneous molecular weight distribution of the block polymer is particularly suitable for the composition of polymer electrolytes.

[0026] Within the scope of preferred embodiments of this method, to functionalize a polar polymer block, the block may be deprotonated with a base selected from the group consisting of lithium hydride, sodium hydride, potassium hydride, potassium tert-butanolate, lithium tert-butanolate, sodium tert-butanolate, potassium metal, sodium metal, lithium metal, lithium bis(trimethylsilyl)amide, or mixtures thereof, and then reacted with epichlorohydrin. In selecting the base used to deprotonate the terminal hydroxyl groups of the PEG-based chain, it is important that it is a strong base but also a weak nucleophile. Reaction time, the concentrations of the components or their relative concentrations, the solubility of the individual components, and the chemical properties of the salt formed by the final functionalization all play important roles in the quantitative transformation. This is all the more true because the oligomeric reactants and the epoxide-terminated functionalized products are almost indistinguishable from each other by analysis, and if the transformation is incomplete, they cannot be separated from each other. This base selection has proven particularly suitable for achieving complete transformation within a short reaction time.

[0027] In further embodiments of this method, the nonpolar solvent may be selected from the group of aromatic hydrocarbons or mixtures thereof. In particular, a particularly low PDI of the block copolymer can be obtained by carrying out the coupling of different blocks in a solvent such as toluene or benzene. Without being bound by theory, this may be due to a special interaction between the solvent and the lithium ions and negatively charged adduct, which particularly efficiently prevents further reactions at this center and thus contributes to a particularly controllable addition reaction.

[0028] Within the scope of a more preferred embodiment of this method, the Li organyl initiator may be an alkyllithium initiator having a pKa value of 50 or higher. The structure of the nonpolar block and the bonding of the polar block according to the present invention can be particularly favorably expressed via an alkyllithium initiator having a pKa value of 50 or higher. This method of control results in block polymers with very defined low polydispersity and can significantly reduce the effort required for separation and purification of block copolymers.

[0029] Furthermore, according to the present invention, block copolymers are obtained by the method of the present invention. The method of the present invention can yield BPCs having a more uniform structure compared to block copolymers known from the prior art. A very large number of combinations of different monomers having different polarities can be processed, and in this regard, regularly occurring block copolymers become available, which cannot be obtained by this method via the prior art methods. Different blocks are bonded in such a way that the structure of the individual blocks and the steric interactions between BCPs are not interfered with as much as possible. As a result, more uniform mechanical and ionic conductive properties are obtained. The reaction can be highly controlled so that there are only very small deviations in molecular weight for individual BCPs. Representative uniformity in terms of molecular weight cannot be obtained by this method via multiple sequential anionic polymerization or equivalent methods for constructing regularly occurring block copolymers.

[0030] In a more preferred embodiment, the block polymer comprises, according to the present invention, a non-polar block of a conjugated diene, styrene, its derivatives, or mixtures thereof, and a polar polymer block of ethylene oxide having a molecular weight of 450 g / mol or more and 3000 g / mol or less, wherein the polar polymer block reacts with epichlorohydrin and is once covalently bonded to the non-polar block via epoxy groups remaining in the polar block. The advantages of this block copolymer are discussed in the scope of the methods and uses according to the present invention.

[0031] In preferred embodiments of block copolymers, the polar blocks and the block copolymer as a whole may have a polydispersity of 1.0 or greater and 1.05 or less. In addition to the chemical homogeneity of the bonding sites of the different polymer blocks, both the polar blocks and the BPC as a whole that can be obtained may have a highly reproducible molecular weight. Thus, the monodisperse molecular weight distribution of the polymer aggregate is obtained from the polydispersity calculated from the ratio to the number mean by weight. The molecular weight of individual BPCs can then be obtained, for example, by GPC measurement. Preferably, the polydispersity of the block copolymer that can be obtained may be 1.0 or greater and 1.05 or less, and more preferably 1.0 or greater and 1.04 or less.

[0032] Within the range of more preferred embodiments of the block copolymer, the block copolymer may have a molecular weight of 20 kg / mol or more and 250 kg / mol or less. In particular, the block copolymer of the present invention may be a short-chain to medium-chain copolymer within the molecular weight range shown above. Through the use of relatively short polar polymer blocks within the block copolymer, an essentially non-polar block polymer can be obtained in which the short polar domains can preferentially bond to one another. Combined with the property that the polar blocks are ideally all the same length, a significantly improved regular structure can be provided. This advantage of improved self-assembly can be observed particularly when alkali ions, especially lithium ions, are intercalated into the regular polar polymer structure that is formed. Preferably, the molecular weight may be 25 kg / mol or more and 150 kg / mol or less, more preferably 30 kg / mol or more and 110 kg / mol or less.

[0033] Within the range of more preferred embodiments of the block copolymer, the polar polymer block may be an ethylene oxide block having a molecular weight of 450 g / mol or more and 3000 g / mol or less. The advantages of improved self-assembly through the intercalation of multiple polymers may be particularly evident when relatively short-chain polar ethylene oxide blocks are present. Within a generally non-polar polymer block, individual short polar domains can fuse to form at least partially crystalline or layered structures. These highly regular structures allow for particularly good dispersion of alkali metal ions. In this sense, a specific molecular weight range may help to obtain improved ionic conductivity in the electrolyte of the multiple block polymers.

[0034] According to the preferred characteristics of the block copolymer, the nonpolar polymer block may be a polyisoprene-polystyrene diblock polymer, and the polar polymer block may be an ethylene oxide block, with the weight ratio of polar to nonpolar block polymers, expressed as the weight of polar blocks divided by the weight of total BCPs, being between 0.5% and 10%. Within the range of these properties of nonpolar and polar blocks, particularly suitable block copolymers may be provided, especially in combination with a highly reproducible molecular weight distribution. These block copolymers may be particularly suitable for use as a base structure in alkali metal batteries, thereby improving ionic conductivity, which can be achieved based on very low polydispersity. More preferably, the weight ratio may be between 1% and 7%, and even more preferably between 1.5% and 6%.

[0035] Furthermore, the use of the block copolymer according to the present invention for use as a polymer electrolyte in alkaline-ion batteries is also according to the present invention. Due to its highly reproducible regular structure, BCPs produced according to the present invention are particularly suitable for constructing polymer electrolytes in alkaline-ion batteries. The polymer electrolyte, as a whole, comprises at least one alkali ion salt, a solvent, and a block polymer according to the present invention. Optionally, the electrolyte may contain a residual solvent remaining in the product. The residual solvent may be firmly "incorporated" into the structure or "held" by the alkali ion salt, and the residual solvent may also be particularly useful in further increasing alkali ion mobility and thus ion charge transport. The combination or association of extremely high local salt concentrations in polar lithium-ion conductive domains within the regular BCP matrix, along with a very short PEO block length, can result in rapid lithium-ion conduction, particularly separated from polymer segment mobility. As a result, 3D structured BCPs achieve high total conductivity of over 1 mS / cm even at lower temperatures (e.g., -20°C) and maintain very high total conductivity over a very wide temperature range, e.g., -20°C to 90°C. Traditional amorphous PEO-based salts in polymer electrolytes achieve this full conductivity only above 80°C. BCP with a very short PEO block also exhibits a 3-4 times increase in lithium ion migration compared to pure salts in PEO. Compared to salts in the PEO system, this shows a more selective increase in lithium ion partial conductivity along with improved mechanical stability. Thus, an improved polymer electrolyte can be obtained, which exhibits both improved ionic conductivity and mechanical properties that can be controlled separately.

[0036] In a more preferred embodiment of use, the EO / alkali ion ratio in the polymer electrolyte of the alkaline ion battery may be 1:1 or greater and 1:20 or less. Improved alignment of block polymers based on the highly reproducible molecular weight distribution of individual block copolymers can contribute, in particular, to the improved conductivity in polymer electrolytes having the above-mentioned EO / alkali ion ratio. The improved conductivity can also be achieved over an extended temperature range, and furthermore, the change in conductivity as a function of temperature can be increased more uniformly over a wider temperature range than in already available polymer electrolytes. For example, all alkali ion salts that are highly soluble in aprotic polar solvents can be used as possible conductive salts. Examples of these conductive salts include LiPF6, LiFSI, similar sulfonylimides, or mixtures thereof. Particularly high conductivity can be achieved, for example, by the conductive salt LiTFSI.

[0037] Furthermore, the polymer electrolyte of the present invention comprises a polymer component of the block copolymer of the present invention. Constructing a polymer electrolyte having a proportion of BCP according to the present invention can significantly improve the ionic conductivity of the polymer electrolyte. For example, the addition of BCP can improve the temperature response and / or ionic conductivity. In many cases, the addition can further increase the mechanical strength of the electrolyte. The addition of BCP according to the present invention to the total polymer component of the polymer electrolyte is preferably 25 wt% or more and 100 wt% or less, more preferably 50 wt% or more and 100 wt% or less, and even more preferably 75 wt% or more and 100 wt% or less.

[0038] In preferred embodiments of the polymer electrolyte, the polymer component of the polymer electrolyte may include the block copolymer according to the present invention. A particular advantage of the BCP according to the present invention may arise to a particularly high degree when the basic polymer structure of the polymer electrolyte is constructed as a whole from the BCP according to the present invention. In these cases, very high ionic conductivity can be obtained over a wide temperature range. Without being bound by theory, this is thought to be due to a particularly favorable alignment of the relatively short polar domains of the different polymers, which leads to particularly efficient conduction of ions as a function of the applied voltage. The polymer electrolyte may consist of the BCP according to the present invention when the proportion of further polymers acting as polymer components of the polymer electrolyte is 5% by weight or less, more preferably 2.5% by weight or less, and even more preferably 1% by weight or less.

[0039] Within the range of more preferred embodiments of the polymer electrolyte, the polymer electrolyte may have a conductivity of 1 mS / cm or more at -20°C. Polymer electrolytes made from BCP according to the present invention may exhibit significantly improved conductivity even at very low temperatures due to the very low PDI of BCP. This is likely due to a small number of undesirable impurity atoms, which can be ensured by consistent fabrication. In addition, the very uniform length of BCP may contribute to a very regular arrangement of polar domains, which has a favorable effect on expressible ionic conductivity.

[0040] According to the desirable characteristics of polymer electrolytes, polymer electrolytes can exhibit conductivity of 1 mS / cm or more over a temperature range of -20°C to 90°C. Surprisingly, the polymer electrolyte of the present invention, containing the polymer component derived from BCP, has been shown to exhibit exceptionally high conductivity, particularly over a wide temperature range. Without being bound by theory, this may be due to a specific arrangement of polar chains, which is achieved by very uniform chain lengths of nonpolar and polar blocks. These structures are considered to be particularly stable over a wide temperature range.

[0041] According to the favorable characteristics of the polymer electrolyte, it may have a residual solvent content of 0.1 wt% or more and 30 wt% or less. Surprisingly, it has been shown that even a small amount of residual solvent in the polymer electrolyte can contribute to improved conductivity. The residual solvent is the solvent used to dissolve the conduction salt and BCP. The residual solvent not only serves as a classical solvent among these but also appears to coordinate with the alkali ion salt incorporated into the BCP. This coordination appears to contribute to the improved conductivity of Li ions, so that very high conductivity can be achieved even at low temperatures. For example, aprotic polar solvents from the group of ethers, carbonates, lactones, esters, nitriles, sulfones, phosphates, or mixtures thereof can be used as the “relevant” residual solvent. For example, the use of THF, PC, GBL, MTBE, or DMC, or mixtures of at least two of these, has been shown to be particularly advantageous. The remarkable effect can already be achieved at a weight fraction of 20% by weight or less, preferably 15% by weight or less, where the weight fraction is based on the weight of the polymer electrolyte consisting of the polymer, conduction salt, and solvent.

[0042] Furthermore, the Li-ion battery according to the present invention includes the polymer electrolyte according to the present invention. The advantages of the Li-ion battery according to the present invention are explicitly referenced to the advantages of the BCP according to the present invention and the advantages of the polymer electrolyte according to the present invention that can be produced therefrom. [Brief explanation of the drawing]

[0043] Further advantages and advantageous embodiments of the object of the present invention are illustrated by the drawings and described in the following embodiments. It should be noted that the drawings are for illustrative purposes only and are not intended to limit the invention in any way. [Examples]

[0044] The BCP is constructed from two nonpolar and one short polar block. The short polar block is a "prefabricated" PEO block, which is covalently bonded to the two polymer blocks constructed by sequential living anionic polymerization in a one-step, one-time convergent manner.

[0045] The chemicals used had a purity of over 99% and a water content of less than 10 ppm.

[0046] 1. Functionalization of PEO blocks with different molecular weights PEG-based chains with molecular weights of 164 g / mol, 350 g / mol, 750 g / mol, 1000 g / mol, 1900 g / mol, 2000 g / mol, and 3000 g / mol were functionalized.

[0047] All PEO blocks were functionalized as described below and characterized using the same measuring equipment and conditions.

[0048] Under an inert gas atmosphere, 896 mg (9.32 mmol) of the sublimation base, sodium tert-butanolate, is dissolved in 60 mL of sieve-dried THF in a flask at room temperature, with stirring. In parallel, in a separate reaction flask, 12.11 g (6.29 mmol) of a PEG-based chain (mPEG with a chain length of 1900 g / mol, where the 'm' in mPEG indicates that a terminal methyl group is attached to one end of the PEG chain), dried under high vacuum, is dissolved in 60 mL of sieve-dried THF, and the mixture is stirred overnight at room temperature under an inert gas atmosphere. Then, under an inert gas atmosphere, the base dissolved in THF is transferred to the reaction flask and stirred at room temperature for 72 hours under an inert gas atmosphere. After this time, the deprotonation of the PEG-based chain is completed, and then 4.54 g (49.04 mmol) of epichlorohydrin, dried by molecular sieve, is added dropwise within 15 minutes under an inert gas atmosphere, and the mixture is stirred under an inert gas atmosphere at room temperature for approximately 6 days. Then, volatile matter (THF, tert-butanol, and excess epichlorohydrin) is removed under vacuum at a temperature below 60°C. To the dried residue, 40 mL of dry THF is added through a molecular sieve under an inert gas atmosphere, and the mixture is stirred overnight under an inert gas atmosphere at room temperature. Then, the salt formed and precipitated during the reaction is separated from the solution by centrifugation followed by filtration. The solvent is removed under vacuum at room temperature.

[0049] The obtained product is gently heated and dissolved in a small amount of toluene. Pre-cooled diethyl ether is added to precipitate the product, and then the heated solution is centrifuged. The product is dried under vacuum to remove residual diethyl ether and other volatile substances, and then dried under high vacuum for several days.

[0050] The obtained product was quantitatively analyzed. 1 Characterized by 1H-NMR (500 MHz) (Figure 1) and IR spectroscopy. NMR measurements were performed in CDCl3 (7.26 ppm) at T=300 K. 1For 1H NMR spectra, 32 scans are performed using a Bruker AVANCE NEO 500MHz with an acquisition time of 4.72 seconds from FID(AQ) and a waiting time of 30 seconds before the next scan (d1). The spectra are evaluated using the software MestReNova 12.0.4-22023.

[0051] The peaks at chemical shifts of 2.52 ppm, 2.7 ppm, and 3.06 ppm are characteristic of epoxide group protons attached to the PEG chain ends by functionalization, and the intensities of these three peaks are equal, as expected for different protons. The peak at chemical shift of approximately 3.29 ppm can be attributed to the three protons of the methyl group located at the PEG chain ends. The transformation is quantitative, as indicated by the fact that the area under the 3.29 ppm peak corresponds to the sum of the three peaks characteristic of epoxide group protons. The peaks in the chemical shift region of approximately 3.73–3.31 ppm can be attributed to non-terminal (i.e., end-chain group) protons of the PEG chain. In the IR spectrum (not shown), the OH group is not detectable after PEG functionalization.

[0052] 2. Structure of BCP All prepared BCPs were synthesized as described below, with only the initiator and monomer amounts adjusted or changed according to the desired BCP composition. Characterization was performed using the same instruments and measurement conditions.

[0053] Diblock copolymers of polyisoprene (PI) and polystyrene (PS) are constructed by sequential living anionic polymerization and then reacted with terminally functionalized PEG chains to form the corresponding triblock copolymers.

[0054] Sequential living anionic polymerization is carried out at room temperature under an inert gas atmosphere. Toluene, isoprene, and styrene were each dried beforehand using a molecular sieve and freshly distilled under an inert gas atmosphere before use. First, two nonpolar blocks of BCP (first PI, then PS) are constructed. To do this, 134 g of toluene is added to the reaction flask. Next, 178 μL of a 1.43 M cyclohexane solution of the initiator (sec-butyllithium) is added with stirring. Next, 4.02 g (58.97 mmol) of isoprene is added to the reaction solution and reacted overnight with stirring. Next, 9.73 g (93.42 mmol) of styrene is added to the reaction solution and reacted overnight as well. Samples are taken from the reaction solution for GPC measurement of the PI-PS blocks. Next, 0.7598 g (383.28 μmol) of terminally functionalized PEG-based chains (M n Add (1900 g / mol) to the active PI-PS anion solution while stirring. Stir the mixture for 3 days. After this time, add 250 μL of 1.2 M methanol hydrochloric acid to the product, dry it, and dissolve it in dichloromethane. Slowly add the resulting solution dropwise into a methanol template, decant the liquid, and dry the precipitated BCP. Dry the resulting product under high vacuum. A white solid is obtained, which can be quantitatively analyzed. 1 The findings are characterized via 1H-NMR spectroscopy (Figure 2) and GPC chromatography (Figure 3).

[0055] GPC chromatograms of PI-PS blocks (Figure 4) and PI-PS-PEO blocks (Figure 3) were recorded with measurement times of 0–13 minutes and measurement intervals of 100 milliseconds (column TSKgel GMHHR-N, flow rate 1 mL / min, solvent THF, T=40°C). Comparison of GPC chromatograms shows that the added PEO block was too short to produce a significant signal in the GPC chromatogram. n(101,400 g / mol to 107,500 g / mol) The tendency towards is, if any, very slight. However, it can be inferred that the functionalized PEO chain binds to the PI-PS anion exactly once; otherwise, due to the excessive addition of the end-functionalized PEG-based chain to the reaction solution, the M of the BCP n is thought to be higher. A very good polydispersity of less than 1.1 is achieved (polydispersity = M W / M n ).

[0056] Quantitative 1 1H-NMR spectrum (Figure 2) shows a small peak at a chemical shift of 7.26 ppm, which can be attributed to the solvent CDCl3. Peaks in the range of approximately 7.3 - 6.3 ppm can be assigned to the protons of the phenyl radicals of polystyrene. Peaks in the range of approximately 5.3 - 4.6 ppm will be assigned to the protons of the double bonds of (1,4 and 3,4) polyisoprene. The peak at approximately 3.7 ppm will be assigned to the protons of PEO. Since this peak still exists after the purification step of the product, the PEO or PEG chain should be covalently bonded to the non-polar block. After the PEO chain is connected, there can be no further reaction of the epoxide group, so it is considered that the functionalized PEG chain can be connected to the PI-PS anion exactly once. Otherwise, the peak area of the peak at approximately 3.7 ppm would be proportionally larger. Peaks in the range of approximately 2.4 - 1.2 ppm can be assigned to the protons of the polymer backbone. Quantitative 1 1H NMR spectrum proves that the desired regular triblock copolymer was obtained. The molecular weight fractions of the individual monomers are found to be M n,PI = 31.2 kg / mol, M n,PS = 74.4 kg / mol and M n,PEO= 1.9 kg / mol.

[0057] 3. Characterization of the properties of the BCP To obtain a polymer electrolyte from BCP, BCP and a calculated amount of conductive salt are dissolved in a common solvent or solvent mixture. The resulting solution is packed into a Teflon container, and the solvent is slowly evaporated at room temperature under an inert gas atmosphere (over 5 days). The resulting polymer electrolyte film is then compressed to the desired thickness, and suitable fragments of the desired size are punched out.

[0058] The total ionic conductivity measurements of polymer electrolytes derived from BCP prepared according to the present invention with different LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) conductive salt concentrations are shown in Figures 5 and 6. Figure 5 shows the measurements at an EO:Li ratio of 1:4, and Figure 6 shows the measurements at an EO:Li ratio of 1:5. The EO:Li ratio represents how many Li atoms per oxygen atom of the PEO monomer or repeating unit. + This defines the presence or absence of ions. This describes or indicates the concentration of conductive salts within the PEO block of the BCP.

[0059] All total ionic conductivity measurements were performed using the same instrument and experimental setup. For this purpose, the sample to be measured was brought into contact with two stainless steel electrodes in a coin cell. Spectra were measured with an amplitude of 40 mV in the frequency range of 1 Hz to 1 MHz using a Metrohm Multipotentiostat M204 with the FRA32 module and Nova 2.1.4 measurement software. The temperature was controlled in a climate chamber, and evaluation was performed using Zview2.

[0060] Figures 5 and 6 show the Arrhenius plots of total ionic conductivity. In the results shown in Figures 5 and 6, triblock BCP (consisting of PI-PS-PEO) with different lithium conductive salt concentrations were measured using the same synthesis method. The film thickness was 1.159 mm for films with a 1:4 EO:Li ratio (Figure 4) and 1.052 mm for films with a 1:5 EO:Li ratio (Figure 6). The film diameter was 15 mm in all cases.

[0061] Figures 5 and 6 show four measurement curves, each based on two heating cycles (filled symbols) and two cooling cycles (outlined symbols). The sample was first heated from -20°C to 90°C in 5°C steps, and in each case, the impedance spectrum was recorded, from which the corresponding conductivity was determined. The first cycle is indicated by a filled star. Next, the sample was cooled from 90°C to -20°C in 5°C steps, and the impedance or conductivity was measured in each case. This second cycle is characterized by an outlined star. The heating and cooling were then repeated. These two cycles are indicated by filled / outlined circles.

[0062] From the conductivity, it can be seen that there is a jump in total ionic conductivity after the first heating cycle, i.e., in the first cooling cycle. This is a clear indication that the domains of BCP have aligned. The "self-assembly" of BCP occurred with the formation of a very good lithium-ion conducting phase. A salt-rich phase may also have formed. This is important for the BCP of the present invention. In subsequent cooling and heating cycles, the total ionic conductivity approaches a more constant value. This suggests that the structural changes are maintained. A linear increase in total ionic conductivity with increasing temperature is also observed. In the case of a standard PEO electrolyte, there is usually a stronger temperature dependence, as there is a much larger increase in total ionic conductivity at temperatures above 60°C (the glass transition temperature of PEO). Based on the conductivity, it can be further inferred that ion transport is separated from the segment motion of the polymer, since the total ionic conductivity is less temperature-dependent compared to traditional PEO electrolytes. This can be attributed to the extremely slow segment motion of the polymer at low temperatures (below 30°C).

[0063] The total ionic conductivity achieved in Figures 5 and 6 is not yet optimized and can still be improved depending on, for example, the PEO chain length or monomer fraction of BCP, the conduction salt concentration, the membrane infiltration procedure, the amount of residual solvent, and the choice of solvent (see Figures 10-15 and their descriptions).

[0064] Figures 7 and 8 show the quantitative results of a BCP manufactured according to the present invention. 1 Figure 7 shows the 1H-NMR and corresponding GPC chromatograms. The quantitative analysis of BCP having a nonpolar PI-PS block and a short polar PEO block coupled according to the present invention is shown. 1 The 1H NMR spectra are shown. The same peaks as in Figure 2 are observed and described, but depending on the selected BCP composition, only the ratio or chain length of the individual blocks and therefore the intensity of the corresponding peaks differ. This also applies to the NMR of other BCPs that have been prepared, which are not shown here. The molecular weight fractions of the individual monomers and the corresponding PDIs are listed in the table below and can be seen in the DSC curve (Figure 9). The molecular weight fractions of the individual monomers of the BCPs shown in Figures 7 and 8 are M n,PI = 14.5 kg / mol, M n,PS =34.8 kg / mol and M n,PEO = 1.9 kg / mol. Figure 8 shows the corresponding polydispersity index (PDI) of 1.019 and total molecular weight M n,ges This shows the corresponding GPC chromatogram for 51.2 kg / mol. It is hereby shown that block copolymers having very low PDI can be prepared according to the present invention. The polymer is pseudo-monodisperse and exhibits only a single molecular weight.

[0065] Due to the convergent manufacturing method, it is possible to synthesize further block copolymers with various monomer content without any problems. For this purpose, only the addition of initiators, monomers, or terminally functionalized PEG-based chains must be adjusted according to the desired BCP structure. The BCPs obtained by this method were characterized in the same way as those described in Figures 1-4, or in the same way as those described in Figures 7 and 8. The following results are obtained with respect to composition and PDI:

[0066] [Table 1]

[0067] The experiment demonstrates that short polar blocks can be coupled very reproducibly to different non-polar diblock polymers formed by living anionic polymerization. All triblock polymers have a very low polydispersity index of less than 1.04. Such monodispersity is not expressible by modern techniques. Without being bound by theory, this is due in particular to living polymerization resulting in very uniform polymer lengths, and the bonding of defined polar chains does not contribute to increased polydispersity. This is particularly advantageous with respect to very short polar chain blocks, as traditional preparations yield significantly higher deviations in terms of percentage. This low PDI of less than 1.04 is important because the blocks have only the desired size, which leads to the formation of highly regular structures between individual polymers. Thus, exceptionally high ionic conductivity can be brought about by the regular polar regions of the block copolymers. In addition to this, due to the bonding of polar blocks according to the present invention, the polar regions exhibit high chemical homogeneity.

[0068] The four different BCPs listed in the table above were examined using a Liquid Nitrogen Cooling System (LNCS) and DSC (DSC-Q2000, TA-Instruments corp., USA). The baseline (specific heat capacity of the material) was accurately recorded using software-assisted Tzero® technology. To improve measurement accuracy, approximately 10 mg of BCP sample was placed in a hermetically sealed Tzero® aluminum crucible under an inert gas, and its thermal signal was stored in the control software (Thermal Advantage), thereby enabling measurement of the change in specific heat capacity during the glass transition. During measurement, helium was used as a purge gas at a flow rate of 25 mL / min (according to the instrument manufacturer's specifications). The melting signal of an indium standard was used for quantitative evaluation of the enthalpy of fusion. The DSC signal was evaluated using Universal Analysis 2000 software (version 4.5A, build 4.5.0.5). The glass transition signal was evaluated using the "half-height" method, which is obtained from the tangent to the baseline before and after the change in heat capacity. The measurement results are shown in Figure 9.

[0069] The curves in Figure 9 show the DSC results for triblock copolymers with total molecular weights of 51.2, 51.8, 51.7, and 26.0 kg / mol, as shown in the table above, in descending order. The results of a second heating gradient in the temperature range of -145°C to 200°C at a heating rate of 10 K / min are always shown. In the DSC curves of different BCPs, the phase separation of the three distinct polymer blocks is shown in the θ of the polyisoprene block in the range of -66°C to -59°C. g At point θ of the PEO block at approximately 50°C melting point , and the θ of polystyrene blocks in the range of 76℃~88℃ g It can be observed at a single point. The longer the chain length of the polyisoprene or polystyrene block, the greater the θ g It is assumed that the temperature at a point increases, and the amount of change in heat capacity increases.

[0070] By using the method of the present invention, the different BCPs described above can be manufactured while maintaining high total ion conductivity by varying the block length or the ratio of each other. It is possible to design a desired BCP without reducing the total ion conductivity to below that of the PEO reference system by separately optimizing the mechanical properties and ion transport properties (see Figures 10-15). For this to be important, the method according to the present invention ensures a very narrow definition of the chemical design of the ion-conducting block. As a result, unparalleled high lithium ion conductivity and lithium ion concentrations unattainable by other methods have been achieved compared to the associated polymer electrolytes.

[0071] It is particularly noteworthy that polymer electrolytes obtained from triblock copolymers prepared according to the present invention exhibit a constant, nearly "Arrhenius-like" / linear and low-temperature dependence over the entire temperature range (-20 to 90°C). This, along with exceptionally high and reproducible total ionic conductivity, allows for the presence of only less than 4 wt% (see Figures 10 and 11), and in some cases less than 2 wt% (see Figure 12), conductive PEO domains in the BCP, even though 10 -3The conductivity in the S / cm range is 10 at -20°C. -1.5 Conductivity in the S / cm range is achieved at 90°C. This suggests that lithium ions are transported via a "hopping mechanism-like" transport process, or that they can move independently (separately) from the mobility of the polymer segments.

[0072] Figures 10-15 show the temperature dependence of the total ionic conductivity of different triblock copolymers prepared according to the present invention, where in some cases other solvents were also used for solution casting of the polymer electrolytes in the Arrhenius diagram.

[0073] Figure 10 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.2 kg / mol. The block composition corresponds to the data in the table above. Functional bonding of the PEO block was achieved via functionalization with epichlorohydrin. LiTFSI was used as the polymer electrolyte as a conductive salt with an EO:Li ratio of 1:4.24. In addition, less than 18 wt% (based on the total mass of the polymer electrolyte) of THF was still present in the polymer electrolyte as a residual solvent from the solution cast. The measured polymer electrolyte membrane had a layer thickness of 440 μm and a diameter of 6 mm. Two different curves are shown in the figure. The upper curve (star) represents the results at equilibrium with a constant conductivity. The lower curve (square) represents the results from the first heating cycle. To form reproducible reversible conductivity, the system must first be heated to 90°C (above the glass transition temperature of polystyrene) at least once to bring the system to thermodynamic equilibrium (see the preceding description of Figures 5 and 6 in this regard). Without being bound by theory, the formation of regular polymer structures between individual BCPs, the intercalation of Li ions into polar domains, and the alignment of ion-loaded polar domains into coherent "conductance domains" all appear to require some activation energy, which can be achieved by heating to 90°C at least once. At equilibrium, exceptionally high reproducible total ionic conductivity is observed at -20°C, and 10 -3Conductivity exceeding 45 mS / cm in the S / cm range and at 90°C is observed. Furthermore, the total ionic conductivity exhibits a constant, nearly "Arrhenius-like" / linear and low-temperature dependence across the entire temperature range. This high conductivity is maintained even after intense temperature treatment, i.e., after tempering the sample for several weeks in total, always between -20°C and 90°C. Surprisingly, this observation indicates that residual solvent remaining in the polymer electrolyte is firmly "integrated" into the "structure" and located only within the PEO domains. Moreover, this long-term thermal stability indicates that the lithium ion concentration and highly regular layered structure are stabilized by the BCP prepared according to the present invention.

[0074] Figure 11 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.2 kg / mol for an EO:Li ratio of 1:5.03, using LiTFSI as the conductive salt (see the table above for the composition of the individual blocks). In addition, less than 20 wt% (based on the total mass of the polymer electrolyte) of THF was still present in the polymer electrolyte as a residual solvent from the solution cast. The measured polymer electrolyte membrane had a layer thickness of 240 μm and a diameter of 6 mm. The lower curve (square) shows the result of the first heating cycle, while the three upper curves (star, circle, and triangle) represent the results of different heating curves after reaching equilibrium. At equilibrium, the total ionic conductivity at very low temperatures (-20°C) was 10 -2.5 It is found to be in the S / cm range and has a very slight temperature dependence. At 90°C, this is 10 -1.5 It is in the S / cm range. Compared to the first heating cycle, a jump of 4 decades is achieved in some cases. It is extremely rare for polymer-based solid electrolytes to have lithium-ion conductivity greater than 1 mS / cm at -20°C. In particular, conductivity at -20°C appears to be highly useful for use as an electrolyte in alkaline-ion secondary batteries, according to the current common definition. Typically, the limit of lithium-ion conductivity greater than 1 mS / cm is only achieved above 30°C.

[0075] Figure 12 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is M n,PI = 31.2 kg / mol, M n,PS = 74.4 kg / mol and M n,PEO= The concentration was 1.9 kg / mol, and the results were obtained with an EO:Li ratio of 1:9.75. LiTFSI was used as the conductive salt. In addition, less than 20 wt% (based on the total mass of the polymer electrolyte) of THF was still present in the polymer electrolyte as a residual solvent from the solution cast. The measured polymer electrolyte membrane had a layer thickness of 420 μm and a diameter of 6 mm. The lower curve (square) shows the result of the first heating cycle, while the upper curve (star) shows the result after reaching equilibrium. At equilibrium at -20°C, the lithium ion conductivity is greater than 1 mS / cm, and the total ionic conductivity at 90°C is greater than 50 mS / cm (see Figure 11 for further interpretation of these conductivity values). Furthermore, the total ionic conductivity of the polymer electrolyte shows very low temperature dependence by using BCP prepared according to the present invention. At a PEO chain length of 1900 kg / mol, the total molecular weight of the BCP in Figure 12 (107.5 kg / mol) is approximately twice as high as that of the BCP in Figure 11 (51.2 kg / mol). It is particularly noteworthy that, despite the BCP in Figure 12 having only half the conductive PEO domains compared to the BCP in Figure 11, the extremely high lithium ion conductivity of the polymer electrolytes in Figures 11 and 12 is almost identical. This remarkable result highlights that the method according to the present invention ensures a very narrow definition of the chemical design of the ion-conductive block, and therefore, high lithium ion concentrations unattainable by other methods can be adapted and stabilized in these very short blocks. Highly regular layered structures can be formed independently of the BCP composition (see also Figure 13 and its description).

[0076] Figure 13 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.8 kg / mol, having an EO:Li ratio of 1:4.99 and LiTFSI as the conductive salt. The block composition is shown in the table above. In addition, less than 30 wt% (based on the total mass of the polymer electrolyte) of THF was still present in the polymer electrolyte as a residual solvent from the solution cast. The measured polymer electrolyte membrane had a layer thickness of 360 μm and a diameter of 9 mm. The lower curve (square) shows the results of the first heating cycle, while the upper curve (star) shows the results after reaching equilibrium following the fourth heating cycle. At equilibrium, the total ionic conductivity can be seen to exhibit a linear temperature dependence. The conductivity spike in the measured temperature range (0°C to 90°C) between the first and fourth heating cycles is less than half the magnitude of the decade and is therefore far less noticeable compared to the conductivity spikes from Figures 10-12. The BCP used in this polymer electrolyte was optimized for better handling and electrolyte contact, specifically by varying the proportion or chain length of structured nonpolar blocks (polyisoprene and polystyrene) (see the table above), while the chain length of polar PEO blocks, which are solely responsible for lithium ion transport, remained the same at 1.9 kg / mol. By increasing the polyisoprene content and simultaneously decreasing the polystyrene content, the mechanical properties of the BCP could be controlled to be extremely flexible. Surprisingly, despite the extremely flexible BCP, the highly regular structure of the polymer electrolyte and the associated good total ionic conductivity (exceeding the total ionic conductivity of a standard PEO reference system over the entire temperature range) were not lost. This remarkable result is crucial because it ensures a very strict definition of the chemical design of the ion-conducting PEO blocks, allowing high concentrations of lithium ions, which cannot be obtained by other means, to be intercalated and stabilized in these very short blocks. This makes it possible to form a highly regular structure independently of the BCP composition (see also Figure 12 and its description in this regard).

[0077] Figure 14 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is M n,PI = 31.2 kg / mol, M n,PS = 74.4 kg / mol and M n,PEOThe conductivity was 1.9 kg / mol, and the results were obtained with an EO:Li ratio of 1:2. LiTFSI was used as the conductive salt. In addition, a mixture of MTBE and DMC in less than 13 wt% (based on the total mass of the polymer electrolyte) was still present in the polymer electrolyte as residual solvent from the solution cast. The measured polymer electrolyte membrane had a layer thickness of 620 μm and a diameter of 9 mm. The lower curve (square) shows the result of the first heating cycle, while the upper curve (star) shows the result after reaching equilibrium. At equilibrium, the total ionic conductivity shows a linear temperature dependence and can be seen to exceed the PEO standard reference system over the entire temperature range. This high conductivity is maintained even after intense temperature treatment, i.e., after tempering the sample between 0°C and 90°C for a total of several weeks. Surprisingly, this observation indicates that the suitable solvent choice is not limited to THF. Other solvents or solvent mixtures can be flexibly used without losing the desired ion transport properties of the polymer electrolyte. This remarkable result guarantees a very rigorous definition of the chemical design of ion-conducting PEO blocks, and is therefore crucial that high lithium ion concentrations, which cannot be obtained by other means, are introduced and stabilized in these very short blocks. Highly regular structures are obtained independently of the BCP composition and the choice of solvent or solvent mixture. The solvent molecules appear to be "retained" in the polymer electrolyte. When THF is replaced with another solvent, care must be taken to ensure that the BCP as a whole, not just the conduction salts, is completely dissolved first, so that the conduction salts may precipitate in the PEO blocks / domains due to the slow evaporation of the solvent during solution casting and self-assembly, allowing the conduction domains to align. Preferably, a mixture of at least two solvents can be used for this purpose. For example, combinations of MTBE and DMC or GBL or PC have been found to be particularly advantageous. MTBE can dissolve only the non-polar portion of the BCP containing various conduction salts, while DMC / GBL or PC can dissolve only the polar portion of the BCP containing various conduction salts. (See also Figure 15 and its description).

[0078] Figure 15 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is M n,PI = 31.2 kg / mol, M n,PS = 74.4 kg / mol and M n,PEO The conductivity was 1.9 kg / mol, and the result was obtained using LiTFSI as the conductive salt, with an EO:Li ratio of 1:10.04. In addition, less than 17 wt% (based on the total mass of the polymer electrolyte) from the mixture of THF and PC was still present as residual solvent from the solution cast in the polymer electrolyte. The measured polymer electrolyte membrane had a layer thickness of 400 μm and a diameter of 10.5 mm. The lower curve (square) shows the result of the first heating cycle, while the upper curve (star) shows the result after reaching equilibrium. At equilibrium, in addition to the linear temperature dependence, the total ionic conductivity is found to well exceed the PEO standard reference system over the entire temperature range. This high conductivity is maintained even after intense temperature treatment, i.e., after tempering the sample for a total of several weeks, always between 0°C and 90°C (see the description in Figure 15 for a more detailed interpretation of these conductivityes). In addition to PC, the polymer electrolyte was also prepared and measured with GBL (not shown here) in addition to THF as an additional solvent additive or cosolvent. In all cases, the conductivity is significantly better than that of the PEO standard reference system. Therefore, it can be seen that this very good overall ionic conductivity is not a function of THF alone, but as previously mentioned, a function of the specific structure of BCP, in particular the ionic conductive PEO block and the high concentration of conductive salts within it.

Claims

1. A method for the sequential and convergent preparation of a regular block copolymer comprising at least one nonpolar and one polar polymer block, The nonpolar block is constructed from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, derivatives thereof, or mixtures thereof, via sequential living anionic polymerization with a Li organyl initiator having a pKa of 45 or more. The polarity block is a polymer block having a molecular weight of 350 g / mol or more and 5000 g / mol or less, and composed of monomers selected from the group consisting of C2 to C10 oxacyclo compounds, their derivatives, or mixtures of at least two different monomers thereof. A method characterized in that the polar polymer block is covalently bonded to the nonpolar block anion in a convergent manner via epoxy functionalization of one of the monomers, obtained by the reaction of the monomer of the polar block with an epichlorohydrin in a nonpolar solvent selected from the group of aromatic hydrocarbons or mixtures thereof in the presence of free Li ions.

2. The method according to claim 1, wherein the polarity block is a polyethylene oxide block.

3. The method according to claim 1 or 2, wherein the Li organyl initiator is an alkyllithium initiator having a pKa of 50 or more.

4. A block copolymer comprising at least one nonpolar and one polar polymer block, The nonpolar block is constructed from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, derivatives thereof, or mixtures thereof. The polarity block is a polymer block having a molecular weight of 350 g / mol or more and 5000 g / mol or less, and composed of monomers selected from the group consisting of C2 to C10 oxacyclo compounds, their derivatives, or mixtures of at least two different monomers thereof. The polar polymer block is covalently bonded to the non-polar block via epoxy functionalization of one of the monomers of the polar block. A block copolymer in which the polar block and the block copolymer as a whole have a polydispersity of 1.0 or more and 1.05 or less.

5. The block copolymer according to claim 4, having a molecular weight of 20 kg / mol or more and 250 kg / mol or less.

6. The aforementioned polar polymer block is a polyethylene oxide block. The block copolymer according to claim 4 or 5, wherein the polyethylene oxide block has a molecular weight of 450 g / mol or more and 3000 g / mol or less.

7. The nonpolar polymer block is a polyisoprene-polystyrene diblock polymer. The aforementioned polar polymer block is a polyethylene oxide block. The block copolymer according to any one of claims 4 to 6, wherein the weight ratio of the polar to non-polar block polymer fraction, expressed as the weight of the polar block divided by the weight of the total block polymer, is 0.5% or more and 10% or less.

8. Use of the block copolymer according to any one of claims 4 to 7 for use as a polymer electrolyte in an alkaline ion battery.

9. The use according to claim 8, wherein the EO / alkaline ion ratio in the polymer electrolyte of the alkaline ion battery is 1:1 or more and 1:20 or less.

10. A polymer electrolyte for an alkaline ion battery, characterized in that the polymer component of the polymer electrolyte comprises the block copolymer described in any one of claims 4 to 7.

11. The polymer electrolyte according to claim 10, wherein the polymer component of the polymer electrolyte is a block copolymer according to any one of claims 4 to 7.

12. The polymer electrolyte according to claim 10 or 11, having an ionic conductivity of 1 mS / cm or more at -20°C.

13. The polymer electrolyte according to claim 10 or 11, having an ionic conductivity of 1 mS / cm or more over a temperature range of -20°C or higher and 90°C or lower.

14. A polymer electrolyte according to any one of claims 10 to 13, having a residual solvent content of 0.1 wt% or more and 30 wt% or less.

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