IMPROVED SYNTHESIS FOR THE PROCESSING ORDERED POLYBLOCK COPOLYMERS WITH CONTROLLED MOLECULAR WEIGHT DISTRIBUTION

Description

[0001] The present invention relates to a process for the sequential and convergent synthesis of ordered block copolymers comprising at least one nonpolar and one polar polymer block, wherein the nonpolar block is constructed from specific monomers via a living sequential anionic polymerization using a Li organyl initiator with a pKa value greater than or equal to 45, and the polar block is a polymer block with a molecular weight greater than or equal to 350 g / mol and less than or equal to 5000 g / mol and is composed of monomers selected from the group consisting of C2-C10 oxacyclo compounds, derivatives thereof, or mixtures of at least two different monomers thereof, wherein the polar polymer block is synthesized in one step via an epoxy functionalization of one of the monomers of the polar block, obtained by a reaction of this monomer with epichlorohydrin.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.

[0002] One of the fundamental prerequisites for the rise of portable electrical devices was the availability of sufficiently large and reasonably reliable power sources, which, particularly in the form of alkaline secondary batteries, contributed to unprecedented flexibility and usable operating times under everyday conditions. However, operational safety remains a focus for further development, as solvent-based liquid electrolytes sometimes pose a higher risk of flammability. For this reason, intensive research is being conducted into alternative electrolytes that do not present these inherent hazards.

[0003] Solid electrolytes, such as polymer electrolytes based on polyethylene oxide (PEO) polymers and lithium conducting salts, form a solvent-free class and have been researched since the 1970s. These are safe for application and are commercially available as so-called lithium polymer cells. Current developments are increasing the use of polymer electrolyte cells in demanding and energy-intensive applications such as electromobility. A disadvantage of PEO-based polymer electrolytes is that, as a rule, they can only be used without compromising performance at temperatures above their melting point (approx. 60 °C), as only then are their conductivities sufficient for battery applications.Other potential polymer electrolytes, such as polycarbonates, can also only be processed above their glass transition temperatures and even then exhibit relatively low ionic conductivities for modern high-performance batteries. Furthermore, with these polymers, the partial conductivity of lithium ions cannot be controlled independently of mechanical stability, which is essential for suppressing lithium dendrite growth on lithium metal anodes.

[0004] A starting point for decoupling the mechanical and ion-conducting properties of polymer electrolytes has been identified in the area of ​​ordered micro- and nanostructures of the ion-conducting domains. By using block copolymers (BCPs) with different but ordered block domains, the electrochemical and mechanical properties can be tailored independently. Through the interaction of the polymer segments of the individual block polymers, they undergo self-assembly, forming an ordered network of ion-conducting domains in which consistently decoupled, fast lithium-ion conduction with a simultaneously high transfer number is present. However, a fundamental prerequisite for the formation of highly organized, macroscopic regions is that the block copolymers used exhibit highly reproducible properties.

[0005] Several approaches to the structure and ion-conducting properties of polymer electrolytes made from block copolymers can also be found in the literature.

[0006] For example, Dörr et al. describe possible structures and properties of block copolymers for use as polymer electrolytes 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".

[0007] US patent 2012 / 026 488 0 A1 discloses the synthesis of a block copolymer exhibiting both electronic and ionic conductivity. The synthesis of a block copolymer from poly(3-hexylthiophene) (P3HT) and poly(ethylene oxide) involves a sequential combination of Grignard metathesis polymerization and click reactions.

[0008] Furthermore, US 771,592 2 B1 discloses an implantable medical device that is at least partially formed from a polymer material including 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 to each other by a urea bond. The block copolymer may be a tri-block copolymer, PEO-PIB-PEO, and the base polymer may be a polystyrene-polyisobutylene-polystyrene tri-block copolymer.

[0009] US Patent 2010 252 156 A1 describes a process for producing a diene block copolymer in one step, wherein at least one of these blocks consists of a polyether having a number-average molecular weight of substantially 100 to 5000 g / mol, and at least one other of these blocks consists of a diene elastomer. The process enables a high degree of grafting of the polyether onto the polymer chains. The present invention also relates to a reinforced rubber composition, particularly for the manufacture of tires, which contains such a block copolymer designed to interact with the reinforcing filler. The rubber composition exhibits improved hysteresis properties in the vulcanized state while retaining satisfactory processing properties in the unvulcanized state.

[0010] Other block copolymers are described, for example, in GUO MENGKE ET AL: "Comb-like solid polymer electrolyte based on polyethylene glycol-grafted sulfonated polyether ether ketone", ELECTROCHIMICA ACTA, Vol. 255, pages 396-404, BUTSELE VAN K ET AL: "Synthesis of Novel Amphiphilic and pH-Sensitive ABC Micro-Amp Star Terpolymers", MACROMOLECULES, AMERICAN CHEMICAL SOCIETY, US, Vol. 39, No. 17, January 1, 2006 (2006-01-01), pages 5652-5656, and US 2020 / 102451 A1.

[0011] Such solutions known from the prior art can offer further potential for improvement, particularly with regard to the simplicity, safety, scalability and efficiency of the synthesis, as well as the reproducibility of the block copolymers obtainable via the synthesis.

[0012] It is therefore the object of the present invention to at least partially overcome the disadvantages known from the prior art. In particular, it is the object of the present invention to propose a readily scalable synthesis route that is simple and cost-effective to carry out, provides high yields, and leads to ordered block copolymers with adjustable and defined structure and molecular weight of the individual blocks.

[0013] The problem is solved by the features of the respective independent claims, directed to the inventive method, to block copolymers obtainable by the inventive method, comprising polymer electrolytes, and to the use of the block copolymers thus obtainable as polymer electrolytes in secondary alkaline-ion batteries. Preferred embodiments of the invention are described in the dependent claims, in the description, or in the figures, wherein further features described or shown in the dependent claims, in the description, or in the figures may, individually or in any combination, constitute an object of the invention unless the context clearly indicates otherwise.

[0014] The problem is solved according to the invention by a process for the sequential and convergent production of ordered block copolymers comprising at least one nonpolar and one polar polymer block, wherein the nonpolar block is constructed via a living sequential anionic polymerization using a Li organyl initiator with a pKa value greater than or equal to 45 from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, their derivatives or mixtures thereof, and the polar block is a polymer block with a molecular weight greater than or equal to 350 g / mol and less than or equal to 5000 g / mol and from monomers selected from the group consisting of C2-C10 oxacyclo compounds, their derivatives or mixtures of at least two different monomers thereof, wherein the polar polymer block is constructed in one step via an epoxy functionalization of one of the monomers of the polar block,obtained via a reaction of this monomer with epichlorohydrin, in a nonpolar solvent selected from the group of aromatic hydrocarbons or mixtures thereof, in the presence of free Li ions, convergently covalently linked to the nonpolar blocking anion.

[0015] Surprisingly, it was found that the above-described method can be used to obtain BCPs with two or more different nonpolar / polar blocks, exhibiting a particularly reproducible and uniform distribution of the chain lengths of the individual polymer blocks. Using this method, the exact number of monomers for each polymer block can be determined within very narrow distribution limits, independent of the chemical properties of the monomers used in the individual blocks. The polydispersity index (PDI) of the entire block copolymer, and especially of the short polar block, can be less than 1.04. This method also allows for the flexible preparation of block copolymers that are otherwise difficult to synthesize and cannot be produced at all, or not efficiently, using conventional methods.In particular, the synthesis effort is low, allowing for the fabrication of highly asymmetric BCPs characterized by significantly different block lengths, strongly differing polarities, or even differences in both. The improved structure, with more uniform chain lengths of the copolymer overall and for individual blocks, facilitates access to self-assembled and highly structured BCPs that can exhibit both good mechanical properties and, if desired, controlled ion-conducting properties. For example, BCPs with defined ion-conducting segments can be constructed, such as polymer segments that exhibit decoupled lithium ion movement and thus enable rapid lithium ion transport.This can be achieved particularly well by using highly uniform polar blocks that are very short compared to nonpolar blocks, whereas standard methods lead to greater variations in the number of monomers in the constructed polar blocks. The improved uniformity of monomers in the polar blocks allows several polymers to combine into defined, highly ordered domains, resulting in improved alkali ion conductance across these domains. By using BCPs composed of different monomers and chain lengths, functionalities can be selectively separated and individually optimized. A further advantage is that the synthesis is easily scalable to larger production volumes and generally automatable, since, unlike prior art methods, no solvent or counterion exchange, no toxic gases, and no additional additives or catalysts are required.Furthermore, by linking the polar block according to the invention via specific functionalizations, a very homogeneous polar block can be produced, wherein the functionalization has essentially the same or similar chemical properties as the monomers of the polar block. This can lead to a particularly uniform structure of the polar block, including its connection to the nonpolar block.

[0016] The reaction process can be illustrated, for example, by the following scheme:

[0017] One or more nonpolar blocks A and B are constructed via a living sequential anionic 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 added once convergently and covalently to this nonpolar anionic block (step c is the convergence step). The epoxy functionalization of the polar block (C) can be obtained, for example, by a simple reaction of the polar block (C) with epichlorohydrin (step d). This yields a negatively charged polar / nonpolar block copolymer, which, due to the association of lithium with the negatively charged oxygen of the open epoxy group, does not allow any further addition reactions. Block C is therefore added exactly once. In the absence of lithium, orIf it is not coordinated to the negatively charged oxygen atom, or not sufficiently so, further reactions can occur, which can lead to significantly different molecular weights of the resulting BCPs.

[0018] The process according to the invention is particularly suitable for constructing BCPs with different polar blocks or block lengths. According to the prior art, ordered BCP systems with polar, for example, ion-conducting polymer blocks could previously only be constructed from the respective monomers in a sequential series of polymerization steps based on the fundamental principle of living sequential anionic polymerization. This process requires the sequential application of two different polymerization mechanisms. In particular, the polar block can only be formed via a living anionic ring-opening polymerization. The nonpolar monomers are anionically polymerized via the carbanions, and subsequently, after the exchange of the solvent and the counterion, the polar block is formed via the ring-opening polymerization of the oxygen anions of the opened epoxy rings.

[0019] For example, to construct a lithium-ion-conducting domain based on a polar PEO block during BCP synthesis from the monomer (ethylene oxide gas) according to the state of the art, a complex, two-stage synthesis process is required: a) b) c) d)

[0020] In a first step, a defined polymer block is built up from nonpolar monomers via a living anionic polymerization (step a)). At the end of this step, a polymer anion with lithium as the counterion is present. To attach, for example, polar ethylene oxide to this anionic polymer block, a complex exchange of lithium for potassium is required, since the stronger association of lithium with the anion precludes further reactions, such as those involving ethylene oxide (steps b and c). Only after cation exchange and solvent exchange can ethylene oxide be attached to the block polymer anion via another living (ring-opening) polymerization (step d)). Thus, the defined construction of polar on nonpolar blocks, for example, for the production of ion-conducting di- and tri-blocks and higher-order multi-BCPs, becomes cumbersome and expensive.This contrasts with the inventive production described above, in which BCPs can be synthesized for tailored polymer electrolytes, eliminating the need for toxic and highly explosive ethylene oxide gas and convergently bonding the polar block to the nonpolar anionic polymer block end. An additional advantage is that the inventive method also allows for the reproducible attachment of very short polar blocks.

[0021] The process according to the invention is a process for the sequential and convergent production of ordered block copolymers comprising at least one nonpolar and one polar polymer block. Copolymers are obtained within the process according to the invention. Copolymers are polymers consisting of at least two different monomer units. The different monomer units are not arranged arbitrarily within the polymer chain. The respective monomer units are localized to separate regions of the polymer chain. Accordingly, separate blocks are obtained for each of the different polymers.According to the invention, the polymer chain is assembled sequentially and convergently. This means that the BCP is not produced in a single step, but rather through at least two different, subsequent steps, although the production is carried out as a "one-pot" reaction within the same reaction environment. The initial aggregation occurs convergently through a single reaction of the end-functionalized monomer of the polar block. The subsequent steps each then involve the assembly of at least one individual block of the BCP. It is also possible for a single block to be obtained not as a whole, but through the polymerization of individual monomers. Furthermore, the process yields ordered BCPs.In this context, "ordered" means that the resulting copolymers are capable, in principle, of aligning at least some of the polymer blocks, such as the polar block, in semi-crystalline or crystalline structures. The polymers are thus able to form a defined, ordered structure with each other, at least for certain regions. These ordered structures can be detected, for example, using X-ray scattering methods. The number of different blocks used to form the BCP is not limited in principle. Advantageously, the BCPs have at least two, preferably at least three, different monomer units. The maximum number of different blocks can be less than 10, preferably less than 8, and furthermore preferably less than 5.The terms "nonpolar" and "polar" refer to the polarity of the individual monomers and, consequently, the polarity of the resulting chain segments or blocks. Polar blocks are obtained from polar monomers containing heteroatoms such as oxygen or nitrogen. Halogens are excluded as heteroatoms. Nonpolar monomers or blocks comprise monomers consisting primarily of hydrocarbons, without heteroatoms such as boron, oxygen, nitrogen, sulfur, phosphorus, or halogens. Examples of nonpolar monomers include conjugated dienes, styrenes, vinylnaphatlins, vinylmetalocenes, and vinylsilanes.

[0022] The nonpolar block is constructed via living sequential anionic polymerization using a Li organyl initiator with a pKa value greater than or equal to 45. The monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, their derivatives, or mixtures thereof are chosen. For the construction of ordered BCPs, it has proven particularly advantageous that at least one polymer block is obtained via living anionic polymerization. Living polymerization refers to chain polymerizations in which no termination reactions or chain transfers occur, and monomers are added to an already formed anionic chain structure via a nucleophilic attack by the resulting carbanions. Thus, different blocks can only be linked in order of decreasing pKa values ​​of their monomers. Under "living conditions," very narrow molecular weight distributions can be controlled.Furthermore, under these conditions, clearly defined polymer structures, such as BCPs with fixed sequence lengths, can be generated. One possibility for this type of process is described later in the examples. The nonpolar block consists of nonpolar monomers, and the specified group of monomers can contribute to improved mechanical properties throughout the block polymer. Surprisingly, it has also been shown that these monomers can positively influence the crystallization behavior and properties of the subsequent polar block. Without being bound by theory, the structure achievable via the polar block appears to be influenced and controlled by the framework function of the nonpolar block through the addition of several nonpolar blocks to one another.In particular, a combination of selected nonpolar monomers from the aforementioned group can lead to particularly ordered BCPs using the process according to the invention. The nonpolar monomers can be readily converted into a nonpolar and defined polymer block by means of a living anionic polymerization. These derivatives include singly or multiply substituted conjugated dienes, styrenes, vinylnaphatlines, vinylmetalocenes, and vinylsilanes, whose substituents can consist of linear and / or branched alkyl chains and / or alkoxy chains with a chain length of C1 to C10. Conjugated dienes can be, for example, butadiene, isoprene, or methylisoprene. Styrene derivatives include derivatives such as styrene, 4-methylstyrene, 4-(1-adamanthyl)-alpha-methylstyrene, and 3-(dimethylisopropylsiloxyl)styrene. Vinylmetallocenes can be, for example, vinylferrocene, vinylcobaltocene, vinylmanganocene or vinylnickelocene.Possible lithium organyl initiators comprise at least lithium and an organic residue, wherein the organic residue can be aliphatic or aromatic. In the process according to the invention, the following lithium organyl initiators can be used, for example: alkyllithium such as methyllithium, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, pentyllithium, isopentyllithium, or neopentyllithium. Aromatic lithium organyl initiators include, for example, phenyllithium or naphtyllithium. The corresponding pKa values ​​of the initiator(s) used can be found in the literature.

[0023] The polar block is a polymer block with a molecular weight greater than or equal to 350 g / mol and less than or equal to 5000 g / mol and consists of monomers selected from the group consisting of C2-C10 oxacyclo compounds or mixtures of at least two different monomers therefrom. In particular, the process according to the invention allows for the attachment of very well-defined, polar monomer blocks from the aforementioned group. The proposed synthesis leads to very uniform block copolymers, with a particularly homogeneous molecular weight distribution. This can make the block polymers especially suitable for the construction of polymer electrolytes. According to the invention, relatively short polar chains, rather than individual monomers, are convergently attached to the nonpolar block anion in a single step.The C2-C10 oxacyclo compounds can include, for example, ethylene oxide, propylene oxide, butylene oxide, etc. C2-C4 oxacyclo compounds are particularly preferred for constructing the polar block. The derivatives of the C2-C10 oxacyclo compounds are understood to be simple or multiple substitutions, wherein the substituents can consist of linear and / or branched alkyl chains and / or alkoxy chains with a chain length of C1 to C10.

[0024] The polar polymer block is convergently covalently linked to the nonpolar block anion in a single step via epoxy functionalization of one of the monomers of the polar block, obtained by reacting this monomer with epichlorohydrin in a nonpolar solvent selected from the group of aromatic hydrocarbons or mixtures thereof, in the presence of free lithium ions. The polar polymer block is then linked via chemical functionalization of at least one of the monomers of the polar polymer block chain, with this functionalization then leading to the linkage to the polymer anion of the nonpolar block. Epichlorohydrin reacts with a monomer of the polar block via the chlorine-functionalized carbon atom, leaving an epoxy group attached to the polar block. This epoxy-end-functionalized polar polymer block is capable of forming a single covalent bond with the polymer anion in the reaction environment of the anionic polymerization.Therefore, prior to the reaction, the polar polymer block consists of the polar chain and only the additional, functionally attached epoxy group. The functionalization of the polar block takes place outside the reaction solution of the anionic polymerization. In the manufacturing method according to the invention, this is a convergent synthesis; that is, only the functionalized polar block is added to the anionic polymerization solution. Depending on the choice of functional linkage, the polar polymer block can exhibit more or less consistent chemical and physical properties. If the chemical functionalization is carried out with epichlorohydrin, the resulting epoxy functionality yields chemical properties similar to those of the monomers of the polar block.The attachment of the polar polymer block can be achieved without significant disruption of the polar polymer structure, resulting in very homogeneous properties of the functionalized polar block. This can lead to improved crystalline structures, particularly when several block copolymers assemble into such structures or partially into ordered structures. The reaction must take place in a nonpolar solvent selected from the group of aromatic hydrocarbons or mixtures thereof, in the presence of free lithium ions. Free lithium ions are ions capable of polar / nonpolar coordination to the negatively charged oxygen at the attachment site, thus preventing further reaction at the negatively charged oxygen. Non-free lithium ions are present, for example, as insoluble lithium salts such as LiF or LiCl, or bound at other locations within the block copolymer.These lithium ions, due to their fixed coordination at other positions, cannot interact with the negatively charged oxygen and thus cannot prevent unwanted, additional addition steps. Nonpolar solvents are solvents from the group of aromatic hydrocarbons without heteroatoms. Examples of nonpolar solvents include benzene, toluene, xylene, mesyltene, or other mono- or polyalkylene-substituted derivatives or mixtures of at least two solvents from this group.

[0025] In a preferred embodiment of the process, the polar block can be a polyethylene oxide block. The process according to the invention has proven particularly advantageous in cases where a very short, polar polymer block needs to be linked to a larger, nonpolar polymer block. This configuration is very difficult to implement using prior art methods (so), since consistent control and tracking of the reaction with very short chain lengths is analytically very difficult. Furthermore, with very short polymer chain lengths of the polar polymer block, even small disturbances in the synthesis immediately result in large relative deviations in the composition. Therefore, especially in these synthesis situations, the process according to the invention can contribute to a significantly more reproducible assembly of the individual BCPs.In particular, the process according to the invention enables the joining of highly defined, polar ethylene oxide blocks. The proposed synthesis leads to very uniform block copolymers, with a particularly homogeneous molecular weight distribution. This can make the block polymers especially suitable for the construction of polymer electrolytes.

[0026] In a preferred embodiment of the process, the polar polymer block can be functionalized by deprotonating it with a base selected from the group consisting of lithium hydride, sodium hydride, potassium hydride, potassium tert-butanoate, lithium tert-butanoate, sodium tert-butanoate, potassium metal, sodium metal, lithium metal, lithium bis(trimethylsilyl)amide, or mixtures thereof, and subsequently reacting it with epichlorohydrin. Crucially, the base used to deprotonate the terminal hydroxyl group(s) of the PEG-based chain must be a strong base but also a weak nucleophile. The reaction time, the concentration or concentration ratio of the components, the solubility of the individual components, and the chemical properties of the salt formed by the final functionalization play a decisive role in achieving a quantitative conversion.This is all the more true since the oligomeric starting material and the epoxide-end-functionalized product are analytically almost indistinguishable and cannot be separated if the conversion is incomplete. This choice of base has proven particularly suitable for achieving complete conversion within short reaction times.

[0027] The coupling of the different blocks in solvents selected from the group of aromatic hydrocarbons or mixtures thereof, such as toluene or benzene, leads to particularly low PDIs of the block copolymer: i.e., a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, where the polydispersity is determined by the ratio of the weight-to-number-mean molecular weight, and the molecular weight is obtained via GPC measurements and the conditions defined below. While not bound by theory, this may be due to the specific interaction of the solvent with the lithium ions and the negatively charged adduct, which particularly efficiently prevents further reaction at this center and thus contributes to a highly controllable addition reaction.

[0028] In a further preferred aspect of the process, the Li organyl initiator can be an alkyllithium initiator with a pKa value greater than or equal to 50. The inventive construction of the nonpolar block and the inventive attachment of the polar block can be particularly advantageously achieved using an alkyllithium initiator with a pKa value greater than or equal to 50. This process leads to block polymers with very well-defined and low polydispersity and can also significantly reduce the effort required for separation and purification operations of the block copolymer.

[0029] Furthermore, according to the invention, a block copolymer is obtained by the process according to the invention, wherein the polar block and the entire block copolymer have a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, the polydispersity being the ratio of weight-to-number-mean molecular weight, and the molecular weight being obtained via GPC measurements and the conditions defined below. Using the process according to the invention, BPCs can be obtained which have a more uniform structure compared to block copolymers known from the prior art. A large number of combinations of different monomers, even with different polarities, can be processed, and thus ordered block copolymers become available which are not obtainable via prior art processes.The different blocks are linked in such a way that the structure of the individual blocks and the steric interactions between the BCPs are disturbed as little as possible. This results in more uniform mechanical and ion-conducting properties. The reaction is highly controllable, so that only very small variations in the molecular weights of the individual BCPs occur. Such uniformity of molecular weight cannot be achieved through multiple, sequential anionic polymerizations or comparable processes for building ordered block copolymers.

[0030] In a further preferred embodiment, a block polymer according to the invention can comprise a nonpolar block of conjugated dienes, styrene, their derivatives, or mixtures thereof, and a polar polymer block of ethylene oxide with a molecular weight greater than or equal to 450 g / mol and less than or equal to 3000 g / mol, wherein the polar polymer block is reacted with an epichlorohydrin and covalently bonded to the nonpolar block via the epoxy group remaining on the polar block. The advantages of this block copolymer are discussed in the context of the process and use according to the invention.

[0031] According to the invention, in the block copolymer obtained by the inventive process, the polar block and the entire block copolymer exhibit a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, wherein the polydispersity is determined by the ratio of weight-to-number-mean molecular weight, and the molecular weight is obtained via GPC measurements and the conditions defined below. In addition to the chemical uniformity of the bonding site of the different polymer blocks, both the polar blocks and the overall obtainable BPCs can exhibit a highly reproducible molecular weight. Thus, a monodisperse molecular weight distribution of the entire polymer is obtained, with the polydispersity being calculated from the ratio of weight-to-number-mean. The molecular weight of the individual BPCs can be obtained via GPC measurements and the conditions defined below.The polydispersity of the available block copolymers is greater than or equal to 1.0 and less than or equal to 1.05, and more preferably greater than or equal to 1.0 and less than or equal to 1.04.

[0032] In a further preferred embodiment of the block copolymer, the block copolymer can have a molecular weight greater than or equal to 20 kg / mol and less than or equal to 250 kg / mol. The block copolymers according to the invention can, in particular, be short- to medium-chain copolymers in the molecular weight range specified above. By focusing on relatively short, polar polymer blocks within the block copolymer, a substantially nonpolar block polymer is obtained in which the short polar domains can preferentially align themselves. In combination with the property that the polar blocks are ideally all of the same length, significantly improved, ordered structures can be provided. This advantage of improved self-assembly can be observed particularly during the incorporation of alkali ions, especially lithium ions, into the forming, ordered polar polymer structures.Preferably the molecular weight can be greater than or equal to 25 kg / mol and less than or equal to 150 kg / mol, and further preferably greater than or equal to 30 kg / mol and less than or equal to 110 kg / mol.

[0033] In a further preferred aspect of the block copolymer, the polar polymer block can be an ethylene oxide block, wherein the ethylene oxide block has a molecular weight greater than or equal to 450 g / mol and less than or equal to 3000 g / mol. The advantage of improved self-assembly through the aggregation of multiple polymers can arise particularly in cases where relatively short-chain polar ethylene oxide blocks are present. Within the largely nonpolar polymer block, the individual short polar domains can aggregate to form at least a partially crystalline or lamellar structure. Alkali metal ions, in particular, can diffuse through these highly ordered structures. In this sense, the specified molecular weight range can contribute to the attainment of improved ionic conductivities within an electrolyte composed of multiple block polymers.

[0034] According to a preferred characteristic of the block copolymer, the nonpolar polymer block can be a polyisoprene-polystyrene diblock polymer and the polar polymer block an ethylene oxide block, wherein the weight ratio of the polar to the nonpolar block polymer fractions, expressed as weight of polar block divided by weight of total BCP, is greater than or equal to 0.5% and less than or equal to 10%. Within these proportions between nonpolar and polar blocks, particularly suitable block copolymers can be provided, especially in conjunction with a highly reproducible molar mass distribution. These block copolymers can be particularly suitable for use as a base structure in alkaline metal batteries, where improved ionic conductivities can be achieved based on the very low polydispersity.Preferably, the weight ratio can be greater than or equal to 1% and less than or equal to 7%, and more preferably greater than or equal to 1.5% and less than or equal to 6%.

[0035] Furthermore, according to the invention, a block copolymer is used as a polymer electrolyte in alkaline-ion batteries. The block copolymer is produced according to the inventive method for the sequential and convergent synthesis of ordered block copolymers, wherein the polar block and the entire block copolymer have a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, the polydispersity being the ratio of weight-to-number-mean molecular weight, and the molecular weight being obtained via GPC measurements and the conditions defined below. Due to their highly reproducible, ordered structure, the BCPs produced according to the invention are particularly suitable for the synthesis of polymer electrolytes in alkaline-ion batteries. The polymer electrolyte comprises at least one alkali ion salt, a solvent, and the block polymers according to the invention.The electrolyte in the product may contain residual solvent. This residual solvent can be firmly incorporated into the structure or held by the alkali ion salt, and can contribute to further increasing alkali ion mobility and thus ionic charge transport. A combination or cluster of polar lithium-ion-conducting domains within an ordered BCP matrix with an extremely high local salt concentration, combined with very short PEO block lengths, can lead to rapid lithium ion conduction with decoupling of polymer segment mobility.

[0036] As a result, the 3D-structured BCP achieves a high overall conductivity of greater than 1 mS / cm even at lower temperatures (e.g., -20°C) and maintains this very high overall conductivity over a very wide temperature range, e.g., from -20°C to 90°C. Conventional, amorphous PEO-based salt-in-polymer electrolytes only reach this overall conductivity above 80°C. Furthermore, BCPs with very short PEO blocks exhibit a lithium ion transfer number that is three to four times higher than that of pure salt-in-PEO. This demonstrates a further selective increase in the partial conductivity of lithium ions with improved mechanical stability compared to salt-in-PEO systems. Thus, improved polymer electrolytes can be obtained that can be controlled separately and exhibit both improved ion-conducting and mechanical properties.

[0037] In a further preferred embodiment, the EO / alkali ion ratio in the polymer electrolyte of the alkaline-ion battery can be greater than or equal to 1:1 and less than or equal to 1:20. The improved alignment of the block polymers relative to each other, based on the highly reproducible molecular weight distribution of the individual block copolymers, can contribute to particularly improved conductivity in polymer electrolytes, especially with the EO / alkali ion ratio specified above. The improved conductivity can also be achieved over a wider temperature range, and it is possible for the change in conductivity as a function of temperature to increase more uniformly over a wider temperature range than with previously available polymer electrolytes. For example, any alkali ion salts that are readily soluble in aprotic-polar solvents can be used as conducting salts.Examples of these conducting salts include LiPF₆, LiFSI, analogous sulfonylimides, or mixtures thereof. Particularly high conductivities can be achieved, for example, with the conducting salt LiTFSI.

[0038] Furthermore, according to the invention, a polymer electrolyte is formed, wherein the polymeric components of the polymer electrolyte are block copolymers produced according to the inventive process for the sequential and convergent production of ordered block copolymers, wherein the polar block and the entire block copolymer have a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, wherein the polydispersity is determined by the ratio of weight-to-number-mean molecular weight and the molecular weight is obtained via GPC measurements and the conditions defined below.

[0039] The composition of polymer electrolytes containing a proportion of the BCPs according to the invention can significantly improve the ion-conducting properties of the polymer electrolytes. The addition of the BCPs can, for example, improve the temperature behavior and / or the ionic conductivity. In many cases, the addition can also increase the mechanical strength of the electrolyte. The addition of the BCPs according to the invention, based on the total polymer content of the polymer electrolyte, is preferably greater than or equal to 25 wt.% and less than or equal to 100 wt.%, further preferably greater than or equal to 50 wt.% and less than or equal to 100 wt.%, and even more preferably greater than or equal to 75 wt.% and less than or equal to 100 wt.%.

[0040] The particular advantages of the BCPs according to the invention can be especially pronounced when the polymeric base structure of the polymer electrolytes is entirely composed of the BCPs according to the invention. In these cases, very high ionic conductivities can be achieved over a wide temperature range. While not bound by theory, this appears to be due to a particularly favorable orientation of the relatively short polar domains of the different polymers, which leads to a particularly efficient conduction of ions as a function of an applied voltage. The polymer electrolyte can consist of the BCPs according to the invention if the proportion of other polymers acting as polymeric components of the polymer electrolyte is less than or equal to 5 wt.%, more preferably less than or equal to 2.5 wt.%, and even more preferably less than or equal to 1 wt.%.

[0041] In a further preferred embodiment of the polymer electrolyte, the polymer electrolyte can exhibit a conductivity of greater than or equal to 1 mS / cm at -20°C. Due to the very low PDI of the BCPs, the polymer electrolytes according to the invention, made from the BCPs according to the invention, can provide significantly improved conductivities even at very low temperatures. This can most likely be ensured by the low number of unwanted foreign atoms resulting from the consistent manufacturing process. Furthermore, the very uniform length of the BCPs can contribute to a highly ordered alignment of the polar domains, which has a favorable effect on the achievable ionic conductivity.

[0042] According to a preferred characteristic of the polymer electrolyte, the polymer electrolyte can exhibit a conductivity of greater than or equal to 1 mS / cm in a temperature range of -20°C to 90°C. Surprisingly, it has been found that the polymer electrolytes according to the invention, with polymeric components from the BCPs according to the invention, can provide exceptionally high conductivity over a particularly wide temperature range. While not bound by theory, this may be due to the special arrangement of the polar chains, which is achieved because of the very uniform chain lengths of the nonpolar and polar blocks. These structures appear to be stable over a particularly wide temperature range.

[0043] According to a preferred characteristic of the polymer electrolyte, the polymer electrolyte can have a residual solvent content of greater than or equal to 0.1 wt% and less than or equal to 30 wt%. Surprisingly, it has been shown that a small proportion of residual solvent in the polymer electrolyte can contribute to improved conductivity. The residual solvent is the solvent for dissolving the conducting salt and the BCP (base-concentrated polymer). In these cases, the residual solvents apparently not only act as conventional solvents but also coordinate to the alkali ion salts incorporated in the BCP. This coordination can apparently contribute to improved conductivity of lithium ions, enabling very high conductivities to be achieved even at low temperatures. Suitable "associating" residual solvents include, for example, aprotic-polar solvents from the group of ethers, carbonates, lactones, esters, nitriles, sulfones, phosphates, and mixtures thereof.The use of, for example, THF, PC, GBL, MTBE, or DMC, or mixtures of at least two of these, has proven particularly advantageous. Significant effects can be achieved with a weight fraction of less than or equal to 20 wt%, preferably less than or equal to 15 wt%, where the weight fraction is based on the weight of the polymer electrolyte consisting of polymer, conducting salt, and solvent.

[0044] Furthermore, according to the invention, a lithium-ion battery comprising the polymer electrolyte according to the invention is included. For the advantages of the lithium-ion battery according to the invention, explicit reference is made to the advantages of the BCPs according to the invention and the advantages of the polymer electrolytes according to the invention that can be produced therefrom.

[0045] Further advantages and advantageous embodiments of the invention are illustrated by the figures and explained in the following examples. It should be noted that the figures are for descriptive purposes only and are not intended to limit the invention in any way. Examples

[0046] A BCP is constructed from two nonpolar and one short polar block. The short polar block is a "prefabricated" PEO block, which is convergently covalently linked in a single step to the two polymer blocks built up by a living sequential anionic polymerization.

[0047] The chemicals used had a purity of greater than or equal to 99% and a water content of less than 10 ppm. 1. Functionalization of PEO blocks with different molecular weights

[0048] 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.

[0049] All PEO blocks were functionalized as described below and characterized using the same measuring instruments and measurement conditions.

[0050] Under a protective gas atmosphere, 896 mg (9.32 mmol) of the sublimed base sodium tert-butanoate are dissolved in 60 mL of THF dried over a molecular sieve at room temperature in a flask with stirring. Simultaneously, in another reaction flask under a protective gas atmosphere, 12.11 g (6.29 mmol) of the PEG-based chains dried under high vacuum (mPEG with a chain length of 1900 g / mol; the "m" in mPEG indicates that a terminal methyl group is attached to one end of the PEG chain) are stirred and dissolved overnight in 60 mL of THF dried over a molecular sieve at room temperature under a protective gas atmosphere.

[0051] The base dissolved in THF is then transferred to the reaction flask under a protective gas atmosphere and stirred for approximately 72 h at room temperature. After this time, the deprotonation of the PEG-based chain is complete. 4.54 g (49.04 mmol) of epichlorohydrin, dried using a molecular sieve, are then added dropwise over 15 minutes under a protective gas atmosphere and stirred for approximately 6 days at room temperature. The volatile components (THF, tert-butanol, and excess epichlorohydrin) are then removed under vacuum at a temperature below 60°C. To the dried residue, 40 mL of dry THF is added using a molecular sieve under a protective gas atmosphere, and the mixture is stirred overnight at room temperature. The salt formed and precipitated during the reaction is then separated from the solution by centrifugation and subsequent filtration.The solvent is removed under vacuum at room temperature.

[0052] The resulting product is dissolved in a small amount of toluene with gentle heating. To precipitate the product, the heated solution is centrifuged after the addition of pre-cooled diethyl ether. The product is then dried under vacuum to remove any remaining diethyl ether and other volatile components, and subsequently dried under high vacuum for several days.

[0053] The obtained product is analyzed by quantitative 1< H-NMR (500 MHz) ( Figure 1 The NMR measurements were performed at T = 300 K in CDCl3 (7.26 ppm). For the 1H NMR spectrum of the end-functionalized PEO chains, 32 scans were performed using a Bruker AVANCE NEO 500 MHz transducer with a acquisition time from the FID (AQ) of 4.72 seconds and a waiting time (d1) of 30 seconds. The spectrum was analyzed using MestReNova software version 12.0.4-22023.

[0054] The peaks at chemical shifts of 2.52 ppm, 2.7 ppm, and 3.06 ppm are characteristic of the epoxide group protons attached to the PEG chain end through functionalization. As expected for the different protons, the intensities of these three peaks are equal. The peak at a chemical shift of approximately 3.29 ppm corresponds to the three protons of the methyl group located at the PEG chain end. The reaction is quantitative, as demonstrated by the fact that the area under the 3.29 ppm peak corresponds to the sum of the three peaks characteristic of the epoxide group protons. The peaks in the range of chemical shifts from approximately 3.73 to 3.31 ppm correspond to the non-terminal protons (i.e., the groups at the chain end) of the PEG chain. In the IR spectrum (not shown), no OH groups can be detected after functionalization of the PEG. 2. Structure of the BCP

[0055] All BCPs were synthesized as described below, with only the amounts of initiator and monomer being adjusted or modified according to the desired BCP composition. Characterization was performed using the same instruments and under the same measurement conditions.

[0056] A diblock copolymer of polyisoprene (PI) and polystyrene (PS) is built up by living sequential anionic polymerization and then reacted with the end-functionalized PEG chain to form the corresponding triblock copolymer.

[0057] The living sequential anionic polymerization is carried out under a protective gas atmosphere at room temperature. The toluene, isoprene, and styrene were previously dried using a molecular sieve and freshly distilled under a protective gas atmosphere before use. First, the two nonpolar blocks (PI first, then PS) of the BCP are constructed. For this purpose, 134 g of toluene are placed in a reaction flask. Then, 178 µL of a 1.43 M cyclohexane solution of the initiator (sec-butyllithium) is added while stirring. Next, 4.02 g (58.97 mmol) of isoprene are added to the reaction solution and allowed to react overnight while stirring. Subsequently, 9.73 g (93.42 mmol) of styrene are added to the reaction solution and also allowed to react overnight. A sample is taken from the reaction solution for a GPC measurement of the PI-PS block.Subsequently, 0.7598 g (383.28 µmol) of the end-functionalized PEG-based chain (Mn = 1900 g / mol) is added to the solution of the living PI-PS anion while stirring. The mixture is stirred for 3 days. After this time, the product is treated with 250 µL of 1.2 M methanolic hydrochloric acid, dried, and dissolved in dichloromethane. The resulting solution is slowly added dropwise to a methanol receiving flask, the liquid is decanted, and the precipitated BCP is dried. The resulting product is dried under high vacuum. A white solid is obtained, which is determined by quantitative <1H NMR spectroscopy ( Figure 2 ) and GPC chromatography ( Figure 3 ) is characterized.

[0058] The GPC chromatograms of the PI-PS block ( Figure 4 ) and the PI-PS-PEO block ( Figure 3Measurements were taken with a measurement time of 0–13 min and a measurement interval of 100 msec (column TSKgel GMHHR-N, flow rate 1 mL / min, solvent THF, T = 40°C). A comparison of the GPC chromatograms shows that the added PEO block is too short to produce a significant signal in the GPC chromatogram. If anything, only a slight tendency towards heavier Mn (101,400 g / mol to 107,500 g / mol) is discernible. However, it can be deduced that the functionalized PEO chains were attached to the PI-PS anion exactly once, as otherwise higher Mn of the BCP would result because the end-functionalized PEG-based chains are added to the reaction solution in excess. A very good polydispersity of less than 1.1 is achieved (polydispersity = MW / Mn).

[0059] The quantitative 1< H-NMR spectrum of the triblock copolymer ( Figure 2The graph shows a small peak at a chemical shift of 7.26 ppm, which can be attributed to the solvent CDCl₃. The peaks in the range of approximately 7.3–6.3 ppm are attributed to the protons of the phenyl group of polystyrene. The peaks in the range of approximately 5.3–4.6 ppm are attributed to the protons at the double bonds of (1,4 and 3,4) polyisoprene. The peak at approximately 3.7 ppm is attributed to the protons of PEO. Since this peak is still present even after the purification steps of the product, the PEO or PEG chain must be covalently bonded to the nonpolar block. The functionalized PEG chains could only be bonded to the PI-PS anion once, as no further reaction of the epoxide groups is possible after the bonding of the PEO chain. Otherwise, the peak area at approximately 3.7 ppm would be proportionally larger. The peaks in the range of approximately 2.4–1.2 ppm are attributable to the protons of the polymer backbone.The quantitative <1H NMR spectrum confirms that the desired ordered tri-block copolymer was obtained. The molecular weight fractions of the individual monomers are Mn,PI = 31.2 kg / mol, Mn,PS = 74.4 kg / mol, and Mn,PEO = 1.9 kg / mol. 3. Characterization of the properties of BCPs

[0060] To obtain a polymer electrolyte from BCP, the BCP and the calculated amount of conducting salt are dissolved in a common solvent or solvent mixture. The resulting solution is filled into Teflon vessels, and the solvent is slowly evaporated (over 5 days) at room temperature under a protective gas atmosphere. The resulting polymer electrolyte membrane is then pressed to the desired thickness, and a suitable piece of the required size is die-cut.

[0061] The measurements of the total ionic conductivity of polymer electrolytes from the BCPs produced according to the invention with different LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) conducting salt concentrations are described in the Figures 5 and 6 depicted. The Figure 5 shows measurements with an EO:Li ratio of 1 to 4 and the Figure 6 with an EO:Li ratio of 1 to 5. The EO:Li ratio defines how many Li+ ions are present per oxygen atom of a PEO monomer or repeating unit. This describes or specifies the conductivity concentration within the PEO block of the BCP.

[0062] All measurements of total ionic conductivity are performed using the same measuring instruments and experimental setup. The sample to be measured is contacted in coin cells using two stainless steel electrodes. The spectra are measured with a Metrohm M204 multipotentiostat with an FRA32 module and Nova 2.1.4 measurement software; frequency range 1 Hz to 1 MHz with an amplitude of 40 mV. Temperature control was performed in a climate chamber, and data analysis was carried out using Zview2.

[0063] In Figures 5 and 6 The Arrhenius plot of the total ionic conductivity is shown. In the Figures 5 and 6 The results shown were obtained from triblock BCPs (consisting of PI-PS-PEO) produced from the same synthesis approach but with different lithium conducting salt concentrations. The membrane thickness was 1.159 mm for the membrane with an EO:Li ratio of 1:4 ( Figure 4 ) and 1 0.052 mm for the membrane with an EO:Li ratio of 1 to 5 ( Figure 6The diameter of both membranes was 15 mm.

[0064] In the Figures 5 and 6 Four measurement curves are shown, each based on two heating cycles (filled symbols) and two cooling cycles (unfilled symbols). The samples were first heated from -20°C to 90°C in 5°C increments, with an impedance spectrum recorded and the corresponding conductivity determined from each. The first cycle is indicated by filled stars. The samples were then cooled from 90°C to -20°C in 5°C increments, and the impedance and conductivity were measured at each stage. This second cycle is indicated by unfilled stars. Finally, the samples were heated and cooled again. These two cycles are indicated by filled / unfilled circles.

[0065] The conductivity measurements show that after the first heating cycle, i.e., during the first cooling cycle, there is a sharp increase in the total ionic conductivity. This is a clear indication that the BCP domains have aligned. A self-assembly of the BCP has occurred, forming a highly lithium-ion-conducting phase.

[0066] A salt-rich phase may also have formed. This is crucial for the BCPs according to the invention. In the subsequent cooling and heating cycle, the total ionic conductivity then approaches a more constant value. This indicates that the structural change is maintained. Furthermore, a linear increase in the total ionic conductivity with increasing temperature can be observed. Standard PEO electrolytes typically exhibit a stronger temperature dependence, as the total ionic conductivity increases more significantly at temperatures above 60 °C (the glass transition temperature of PEO). Based on the conductivities, the decoupling of ion transport from the polymer segment movement can also be assumed, since the total ionic conductivity is less temperature-dependent compared to conventional PEO electrolytes.This can be attributed to the fact that at low temperatures (below 30 °C) the segment movement of the polymer is extremely slow.

[0067] The in Figures 5 and 6 The achieved overall ionic conductivity is not yet optimized and can be further improved, for example, as a function of the PEO chain lengths or the monomer content of the BCP, the conducting salt concentration, the membrane preparation process, the residual solvent quantity, and the choice of solvent (see the following). Figures 10 to 15 and their descriptions).

[0068] The Figures 7 and 8 Figure 1 shows a quantitative < 1H NMR and the corresponding GPC chromatogram of a BCP prepared according to the invention. Figure 7 This shows a quantitative 11H NMR spectrum of a BCP with a nonpolar PI-PS block and a short, polar PEO block coupled according to the invention. The same peaks are shown as in Figure 2to be identified and described, whereby only the ratios or chain lengths of the individual blocks and, accordingly, the associated peaks in intensity differ depending on the selected BCP composition. This also applies to the NMRs of the other prepared BCPs not shown here, whose molecular weight fractions of the individual monomers as well as the corresponding PDIs are listed in the following table and shown in the DSC curves ( Figure 9 ) can be seen. The molecular weight fractions of the individual monomers of BCP from Figures 7 and 8 This results in Mn, PI = 14.5 kg / mol, Mn, PS = 34.8 kg / mol, and Mn, PEO = 1.9 kg / mol. Figure 8Figure 1 shows the corresponding GPC chromatogram with a polydispersity index (PDI) of 1.019 and a total molecular weight Mn,ges of 51.2 kg / mol. This demonstrates that, according to the invention, block copolymers with a very low PDI can be prepared. The polymers are virtually monodisperse and exhibit only a single molecular weight.

[0069] Due to the convergent manufacturing process, it is easily possible to synthesize further block copolymers with varying monomer contents. This simply requires adjusting the addition of the initiator, the monomers, or the end-functionalized PEG-based chain according to the desired BCP structure. The resulting BCPs were processed equivalently to those described in the Figures 1 to 4 or as in the Figures 7 and 8 The following results were obtained regarding the composition and the PDI: PI M n in kg / mol PS M n in kg / mol PEO M n in kg / mol M n Total in kg / mol PDI 14,5 34,8 51,2 1,019 35,1 14,8 1,9 51,8 1,032 24,8 25,0 51,7 1,027 6,8 17,3 26,0 1,022

[0070] The experiments demonstrate that short polar blocks can be very reproducibly coupled to various nonpolar diblock polymers built up via living anionic polymerization. All resulting triblock polymers exhibit a very low polydispersity index of below 1.04. Such monodispersities cannot be achieved using state-of-the-art methods. While not bound by theory, this is primarily due to the fact that living polymerization yields very uniform polymer lengths, and the attachment of a defined polar chain does not contribute to an increase in polydispersity. This can be particularly advantageous for very short polar chain blocks, as conventional synthesis leads to significantly higher percentage deviations.This low PDI of < 1.04 is important because the blocks have only one desired size, which leads to the formation of highly ordered structures between the individual polymers. Thus, exceptionally high ionic conductivity can be ensured by the ordered polar regions of the block copolymers. Furthermore, due to the inventive bonding of the polar block, the polar region exhibits high chemical uniformity.

[0071] The four different BCPs from the table above were analyzed using DSC (DSC-Q2000, TA-Instruments Corp., USA) with LNCS (Liquid Nitrogen Cooling System). Software-supported Tzero®< technology was employed for precise baseline recording (material-specific heat capacity). To increase measurement accuracy, approximately 10 mg of the BCP samples were enclosed under protective gas in hermetically sealed Tzero®< aluminum crucibles. The thermal signal of these crucibles is stored in the control software (Thermal Advantage), enabling the measurement of specific heat capacity changes during the glass transition. Helium at a flow rate of 25 mL / min was used as a purge gas (according to the instrument manufacturer's specifications) during the measurements. The melting signal of an indium standard was used for the quantitative evaluation of the enthalpy of fusion. The DSC signals are evaluated using the software Universal Analysis 2000 (Version 4.5A, Build 4.5.0.5).The signals of the glass transition are evaluated using the "half-height" method, which is derived from the tangents to the baseline before and after the change in heat capacity. The measurement results are in the [document / section / etc.]. Figure 9 depicted.

[0072] The curves in the Figure 9The figures represent, in descending order, the DSC results of the triblock copolymers with total molecular weights of 51.2, 51.8, 51.7, and 26.0 kg / mol from the table above. The result of the second heating ramp at a heating rate of 10 K / min in a temperature range of -145 °C to 200 °C is always shown. In the DSC curves of the different BCPs, the phase separation of the three independent polymer blocks can be seen by the ϑg point of the polyisoprene block in the range between -66 °C and -59 °C, the ϑ melting point of the PEO block at around 50 °C, and the ϑg point of the polystyrene block in the range between 76 °C and 88 °C. It is postulated that the greater the chain length in the polyisoprene or polystyrene block, the higher the temperature of the ϑg point and the greater the magnitude of the heat capacity change.

[0073] The inventive method allows the various BCPs described above to be produced by varying the block lengths or their ratios to one another, while maintaining the high overall ionic conductivity. It is possible to optimize the mechanical and ion transport properties separately and to design a desired BCP without the overall ionic conductivity falling below that of a PEO reference system (see [reference]). Figures 10 to 15 Crucially, the inventive method guarantees a very precise definition of the chemical design of the ion-conducting block. This enabled the achievement of lithium ion conductivity that is unrivaled compared to relevant polymer electrolytes, as well as lithium ion concentrations that are otherwise unattainable.

[0074] The polymer electrolytes obtained from the triblock copolymers produced according to the invention are particularly noteworthy because they exhibit a constant, almost "Arrhenius-like" / linear and low temperature dependence over the entire temperature range (from -20 to 90 °C). This fact, together with the exceptionally high and reproducible total ionic conductivity—a conductivity in the range of 10⁻³ S / cm at -20 °C and in the range of 10⁻¹.5 S / cm at 90 °C—is obtained, even though only less than 4 wt.% (cf. Figures 10 and 11 ) and in some cases less than 2% by weight (see below). Figure 12 ) are contained in conductive PEO domains within the BCP. This suggests that the lithium ions are transported or can move independently (decoupled) from the polymer segment mobility via a transport process similar to a "hopping mechanism".

[0075] The Figures 10 to 15The temperature dependence of the total ionic conductivity of various triblock copolymers produced according to the invention is shown, in some cases also using other solvents for the Solution Casting the polymer electrolytes used, in an Arrhenius representation.

[0076] The Figure 10 This shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.2 kg / mol. The composition of the blocks corresponds to the information in the table above. The functional integration of the PEO block was achieved via functionalization with epichlorohydrin. LiTFSI was used as the polymer electrolyte in an EO:Li ratio of 1:4.24. Additionally, less than 18 wt% (based on the total mass of the polymer electrolyte) of THF was present as a residual solvent from the Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane sample had a layer thickness of 440 µm and a diameter of 6 mm. The diagram shows two different curves. The upper curve (stars) represents the results at equilibrium with constant conductivity values. The lower curve (squares) shows the result from the first heating cycle. It can be seen that, in order to achieve a reproducible, reversible conductivity, the system must first be heated at least once to 90 °C (above the glass transition temperature of polystyrene) so that the system is brought into thermodynamic equilibrium (see the previous description in this regard). Figures 5 and 6Without being bound by theory, the formation of ordered polymeric structures between the individual BCPs, the incorporation of Li ions into the polar regions, and the alignment of the ion-laden polar regions into coherent "conductivity domains" all appear to require a certain activation energy, which can be achieved by heating to 90 °C at least once. It is observed that at equilibrium, an exceptionally high and reproducible total ionic conductivity is achieved at -20 °C, with a conductivity in the 10⁻³ < S / cm range and greater than 45 mS / cm at 90 °C. Furthermore, the total ionic conductivity exhibits a constant, almost linear, and low temperature dependence across the entire temperature range. This high conductivity is maintained even after intensive temperature treatment, i.e., the sample was continuously temperature-controlled between -20 °C and 90 °C for several weeks.This observation surprisingly shows that the residual solvent remaining in the polymer electrolyte is firmly incorporated into the structure and is located only in the PEO domain. Furthermore, this long-term thermal stability demonstrates that both the lithium ion concentration and the highly ordered lamellar structure are stabilized by the BCP produced according to the invention.

[0077] The Figure 11 This shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.2 kg / mol (see the table above for the composition of the individual blocks) for an EO:Li ratio of 1:5.03, using LiTFSI as the conducting salt. Additionally, less than 20 wt% (based on the total mass of the polymer electrolyte) of THF was present as a residual solvent from the Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane segment had a layer thickness of 240 µm and a diameter of 6 mm. The lower curve (squares) shows the results of the first heating cycle, while the upper three curves (stars, circles, and triangles) represent results of different heating curves after reaching equilibrium. It can be seen that at equilibrium, the total ionic conductivity at very low temperatures (-20 °C) is in the 10⁻².5 < S / cm range and exhibits very low temperature dependence. At 90 °C, it is in the 10⁻¹.5 < S / cm range. Compared to the first heating cycle, a jump of up to four decades is achieved. It is highly unusual for a polymer-based solid electrolyte to exhibit a lithium-ion conductivity greater than 1 mS / cm at -20 °C.In particular, the conductivity at -20 °C, according to the currently accepted definition, appears highly suitable for use as an electrolyte in alkaline-ion secondary batteries. Normally, the limit of lithium-ion conductivity greater than 1 mS / cm is only reached above 30 °C.

[0078] The Figure 12 This shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is as follows: Mn,PI = 31.2 kg / mol, Mn,PS = 74.4 kg / mol, and Mn,PEO = 1.9 kg / mol. The results were obtained with an EO:Li ratio of 1:9.75. LiTFSI was used as the conducting salt. Additionally, less than 20 wt% (based on the total mass of the polymer electrolyte) of THF was present as a residual solvent from the Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane sample had a thickness of 420 µm and a diameter of 6 mm. The lower curve (squares) shows the results of the first heating cycle, while the upper curve (stars) represents the results after reaching equilibrium. It can be seen that 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 the description for further interpretation of these conductivities). Figure 11 Furthermore, it is shown that the overall ionic conductivity of the polymer electrolytes exhibits a very low temperature dependence when using the BCPs produced according to the invention. It is particularly noteworthy that the very high lithium-ion conductivities of the polymer electrolytes are derived from Figures 11 and 12 They can hardly be distinguished from each other, although the BCP is made of Figure 12 compared to the BCP Figure 11only has about half the conductive PEO domains, since with the same PEO chain length of 1900 kg / mol the total molecular weight of the BCP is Figure 12 at 107.5 kg / mol, it is approximately twice as high as the total molecular weight of 51.2 kg / mol from Figure 11 Crucial to this surprising result is that the inventive method guarantees a very precise definition of the chemical design of the ion-conducting block, thereby enabling the accommodation and stabilization of an otherwise unattainable high lithium ion concentration within these very short blocks. Highly ordered lamellar structures can form independently of the BCP composition (see also in this regard). Figure 13 and its description).

[0079] The Figure 13This shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 51.8 kg / mol, an EO:Li ratio of 1:4.99, and LiTFSI as the conducting salt. The block composition is given in the table above. Additionally, less than 30 wt.% (based on the total mass of the polymer electrolyte) of THF was present as a residual solvent from the Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane sample had a layer thickness of 360 µm and a diameter of 9 mm. The lower curve (squares) shows the results of the first heating cycle, while the upper curve (stars) represents the results after reaching equilibrium following the fourth heating cycle. It can be seen that at equilibrium, the total ionic conductivity exhibits a linear temperature dependence. The conductivity jump in the measured temperature range (from 0 °C to 90 °C) between the first and fourth heating cycles is less than half a decade and is therefore significantly smaller compared to the conductivity jumps shown in Figures 10 to 12. The BCP used in this polymer electrolyte was optimized for improved processing and electrode contacting; that is, the proportions or chain lengths of the structure-forming nonpolar blocks (polyisoprene and polystyrene) were varied (see Figure 10).(See table above), where the chain length of the polar PEO block, responsible solely for lithium ion transport, remained constant at 1.9 kg / mol. By increasing the polyisoprene content and simultaneously reducing the polystyrene content, the mechanical properties of the BCP could be controlled to achieve high flexibility. Remarkably, despite the BCP's high flexibility, the highly ordered structure and the associated good overall ionic conductivity of the polymer electrolyte (above that of the standard PEO reference system across the entire temperature range) were retained. Crucially, this remarkable result is due to the very precise definition of the chemical design of the ion-conducting PEO block, which allows for the incorporation and stabilization of an otherwise unattainable high lithium ion concentration within these very short blocks.This allows the highly ordered structure to form independently of the BCP composition (see also in this regard . Figure 12 and their description).

[0080] The Figure 14 Figure 1 shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is as follows: Mn,PI = 31.2 kg / mol, Mn,PS = 74.4 kg / mol, and Mn,PEO = 1.9 kg / mol. The results were obtained with an EO:Li ratio of 1:2. LiTFSI was used as the supporting electrolyte. Additionally, less than 13 wt% (based on the total mass of the polymer electrolyte) of a mixture of MTBE and DMC was present as a residual solvent. Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane sample had a thickness of 620 µm and a diameter of 9 mm. The lower curve (squares) shows the results of the first heating cycle, while the upper curve (stars) represents the results after reaching equilibrium. It can be seen that at equilibrium, the total ionic conductivity exhibits a linear temperature dependence and remains above the PEO standard reference system across the entire temperature range. This high conductivity is maintained even after intensive temperature treatment, i.e., the sample was subjected to temperatures between 0 °C and 90 °C for a total of several weeks. This observation surprisingly demonstrates that suitable solvent selection is not limited to THF. Other solvents or solvent mixtures can be used flexibly without compromising the desired ion transport properties of the polymer electrolyte.Crucial to this surprising result is the guarantee of a very precise definition of the chemical design of the ion-conducting PEO block, which allows for the introduction and stabilization of an otherwise unattainable high lithium ion concentration within these very short blocks. Highly ordered structures result, independent of the BCP composition and the choice of solvent or solvent mixture. The solvent molecules appear to be "trapped" in the polymer electrolyte. When replacing the THF with another solvent, care must be taken to ensure that not only the conducting salt but also the entire BCP dissolves completely first, so that the conducting salt can be dissolved by the slow evaporation of the solvent. solution casting and that self-assemblyto be incorporated into the PEO block / domain, allowing the conductive domains to align. Preferably, a mixture of at least two solvents can be used for this purpose. Combinations of MTBE and DMC, GBL, or PC, for example, have proven particularly advantageous. MTBE can readily dissolve only the nonpolar part, and DMC / GBL or PC only the polar part of the BCP, including the various conducting salts. (See also [reference to be added]) Figure 15 and their description).

[0081] The Figure 15This shows the results for a PI-PS-PEO triblock copolymer with a total molecular weight of 107.5 kg / mol. The block distribution is as follows: Mn,PI = 31.2 kg / mol, Mn,PS = 74.4 kg / mol, and Mn,PEO = 1.9 kg / mol. The results were obtained with an EO:Li ratio of 1:10.04, using LiTFSI as the conducting salt. Additionally, less than 17 wt% (based on the total mass of the polymer electrolyte) of the THF / PC mixture was present as a residual solvent. Solution Castingin the polymer electrolyte. The measured polymer electrolyte membrane sample had a layer thickness of 400 µm and a diameter of 10.5 mm. The lower curve (squares) shows the results of the first heating cycle, while the upper curve (stars) represents the results after reaching equilibrium. It can be seen that at equilibrium, the total ionic conductivity, in addition to its linear temperature dependence, is also significantly higher than that of the PEO standard reference system across the entire temperature range. This high conductivity is maintained even after intensive temperature treatment, i.e., the sample was continuously heated between 0 °C and 90 °C for several weeks (see the description for a more detailed explanation of these conductivities). Figure 15In addition to PC, polymer electrolytes with GBL (not shown here) were also prepared and measured alongside THF as an additional solvent additive or co-solvent. In all cases, the conductivity is significantly better than that of the PEO standard reference system. It can therefore be seen that this very good overall ionic conductivity is not solely a function of the THF, but, as previously described, is due to the special structure of BCP, in particular the ion-conducting PEO block and the high concentration of conducting salts within it.

Claims

1. Process for the sequential and convergent preparation of ordered block copolymers comprising at least one non-polar and one polar polymer block, characterized in that the non-polar block is built up via a living sequential anionic polymerization by means of a Li-organyl initiator having a pKa greater than or equal to 45 from monomers selected from the group consisting of conjugated dienes, styrene, vinylsilane, vinylnaphthalene, vinylmetallocene, their derivatives or mixtures thereof and the polar block is a polymer block having a molecular weight greater than or equal to 350 g / mol and less than or equal to 5000 g / mol and being composed of monomers selected from the group consisting of C2-C10 oxacyclo compounds, their derivatives or mixtures of at least two different monomers thereof, wherein the polar polymer block being covalently linked in a convergent manner to the non-polar block anion via an epoxy functionalization of one of the monomers of the polar block, obtained via a reaction of this monomer with epichlorohydrin, in a non-polar solvent selected from the group of aromatic hydrocarbons or mixtures thereof in the presence of free Li ions.

2. Process according to claim 1, wherein the polar block is a polyethylene oxide block.

3. Process according to any one of the preceding claims, wherein the Li-organyl initiator is an alkylithium initiator having a pKa greater than or equal to 50.

4. Block copolymer obtained by a process according to any one of claims 1 - 3, wherein the polar block and the whole block copolymer have a polydispersity of greater than or equal to 1.0 and less than or equal to 1.05, wherein the polydispersity is calculated via the ratio of a weight mean to a number mean of the molecular weight and the molecular weight is obtained via GPC measurements according to the conditions defined in the description.

5. Block copolymer according to claim 4 5, wherein the block copolymer has a molecular weight of greater than or equal to 20 kg / mol and less than or equal to 250 kg / mol, and the molecular weight is measured according to the description.

6. Block copolymer according to any one of claims 4-5, wherein the polar polymer block is a polyethylene oxide block, wherein the polyethylene oxide block has a molecular weight greater than or equal to 450 g / mol and less than or equal to 3000 g / mol.

7. Block copolymer according to any one of claims 4-6, wherein the non-polar polymer block is a polyisoprene-polystyrene diblock polymer and polar polymer block is a polyethylene oxide block, wherein the weight ratio of polar to non-polar block polymer fractions, expressed as weight polar block divided by weight total block polymer, is greater than or equal to 0.5% and less than or equal to 10%.

8. Use of a block copolymer according to any one of claims 4 - 7 for use as polymer electrolyte in alkali ion batteries.

9. Use according to claim 8, wherein the EO / alkali ion ratio in the polymer electrolyte of the alkaline ion battery is greater than or equal to 1:1 and less than or equal to 1:20.

10. Polymer electrolyte for an alkali ion battery, characterized in that the polymer components of the polymer electrolyte comprise the block copolymers according to any one of claims 4 - 7.

11. Polymer electrolyte according to claim 10, wherein the polymer components of the polymer electrolyte consist of block copolymers according to claim 10.

12. Polymer electrolyte according to any one of claims 10 or 11, wherein the polymer electrolyte has an ionic conductivity at -20°C of greater than or equal to 1 mS / cm, wherein the ionic conductivity is measured according to the description.

13. Polymer electrolyte according to any one of claims 10 to 12, wherein the polymer electrolyte has an ionic conductivity of greater than or equal to 1 mS / cm in a temperature range of greater than or equal to -20°C and less than or equal to 90°C, wherein the ionic conductivity is measured according to the description.

14. Polymer electrolyte according to any one of claims 10 - 13, wherein the polymer electrolyte has a residual solvent content of greater than or equal to 0.1 wt% and less than or equal to 30 wt%.