Synthesis and Post-Polymerization Modification of Defined Functional Poly(vinyl ether)s

Living cationic polymerization is known for a good control over chain growth yielding polymers with well-defined molar mass distributions and low dispersities. However, the practical challenges involved in the synthesis of poly(vinyl ether)s limited suitable post-polymerization modifications (PPM) via chemoselective click reactions. Herein the successful controlled cationic polymerization of vinyl ethers bearing pendant CC double and C≡C triple bonds using a single-component initiation under ambient conditions is reported. Furthermore, the PPM via thiol-ene/-yne and copper(I)-catalyzed alkyne-azide cycloaddition reaction of the obtained polymers is successfully realized laying the foundation for the synthesis of unprecedented functional poly(vinyl ether)s

Poly(ethylene oxide)-Based Electrolytes for Solid-State Potassium Metal Batteries with a Prussian Blue Positive Electrode

Potassium-ion batteries are an emerging post-lithium technology that are considered ecologically and economically benign in terms of raw materials’ abundance and cost. Conventional cell configurations employ flammable liquid electrolytes that impose safety concerns, as well as considerable degrees of irreversible side reactions at the reactive electrode interfaces (especially against potassium metal), resulting in a rapid capacity fade. While being inherently safer, solid polymer electrolytes may present a solution to capacity losses owing to their broad electrochemical stability window. Herein, we present for the first time a stable solid-state potassium battery composed of a potassium metal negative electrode, a Prussian blue analogue K₂Fe[Fe(CN)₆] positive electrode, and a poly(ethylene oxide)-potassium bis(trifluoromethanesulfonyl)imide polymer electrolyte. At an elevated operating temperature of 55 °C, the solid-state battery achieved a superior capacity retention of 90% over 50 cycles in direct comparison to a conventional carbonate-based liquid electrolyte operated at ambient temperature with a capacity retention of only 66% over the same cycle number interval

Improved Route to Linear Triblock Copolymers by Coupling with Glycidyl Ether-Activated Poly(ethylene oxide) Chains

Poly(ethylene oxide) block copolymers (PEO$_z$ BCP) have been demonstrated to exhibit remarkably high lithium ion (Li$^+$) conductivity for Li$^+$ batteries applications. For linear poly(isoprene)-b-poly(styrene)-b-poly(ethylene oxide) triblock copolymers (PI$_x$PS$_y$PEO$_z$), a pronounced maximum ion conductivity was reported for short PEO$_z$ molecular weights around 2 kg mol$^{−1}$. To later enable a systematic exploration of the influence of the PI$_x$ and PS$_y$ block lengths and related morphologies on the ion conductivity, a synthetic method is needed where the short PEO$_z$ block length can be kept constant, while the PI$_x$ and PS$_y$ block lengths could be systematically and independently varied. Here, we introduce a glycidyl ether route that allows covalent attachment of pre-synthesized glycidyl-end functionalized PEO$_z$ chains to terminate PI$_x$PS$_y$ BCPs. The attachment proceeds to full conversion in a simplified and reproducible one-pot polymerization such that PI$_x$PS$_y$PEO$_z$ with narrow chain length distribution and a fixed PEO$_z$ block length of z = 1.9 kg mol$^{−1}$ and a Đ = 1.03 are obtained. The successful quantitative end group modification of the PEO$_z$ block was verified by nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). We demonstrate further that with a controlled casting process, ordered microphases with macroscopic long-range directional order can be fabricated, as demonstrated by small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has already been shown in a patent, published by us, that BCPs from the synthesis method presented here exhibit comparable or even higher ionic conductivities than those previously published. Therefore, this PEO$_z$ BCP system is ideally suitable to relate BCP morphology, order and orientation to macroscopic Li$^+$ conductivity in Li$^+$ batteries

Synthesis and Post‐Polymerization Modification of Defined Functional Poly(vinyl ether)s

Living cationic polymerization is known for a good control over chain growth yielding polymers with well-defined molar mass distributions and low dispersities. However, the practical challenges involved in the synthesis of poly(vinyl ether)s limited suitable post-polymerization modifications (PPM) via chemoselective click reactions. Herein the successful controlled cationic polymerization of vinyl ethers bearing pendant CC double and C≡C triple bonds using a single-component initiation under ambient conditions is reported. Furthermore, the PPM via thiol-ene/-yne and copper(I)-catalyzed alkyne-azide cycloaddition reaction of the obtained polymers is successfully realized laying the foundation for the synthesis of unprecedented functional poly(vinyl ether)s

A Systematic Study of Vinyl Ether-Based Poly(Ethylene Oxide) Side-Chain Polymer Electrolytes

Herein, we report on the synthesis of a systematic library of vinyl ether-based poly(ethylene oxide) (PEO) side-chain copolymers in order to reduce the crystallization of PEO. The influence of different grafted PEO side chain lengths, the grafting density, and the [Li+]:[EO] ratio after mixing with LiTFSI on the glass transition temperature (Tg), the crystallinity, and the resulting ionic conductivity was examined. Copolymers bearing longer PEO side chains and higher grafting densities show higher crystallization tendencies while their Tg is reduced at the same time. Furthermore, the addition of LiTFSI reduces crystallization but increases Tg. Because these effects are directly impacting the ionic conductivity, we demonstrate that the different parameters need to be carefully adjusted in order to balance their influence. In this way, a fundamental view that shows the potential of PEO side-chain copolymers for their applications as polymer electrolytes is provided

Datasets to Impact of Nano-sized Inorganic Fillers on PEO-based Electrolytes for Potassium Batteries

<p>This dataset provides the raw data to the manuscript</p><p><strong>"Impact of Nano‐Sized Inorganic Fillers on PEO‐Based Electrolytes for Potassium Batteries"</strong></p><p>published in Batteries & Supercaps, <strong>2023</strong>, e202300404. https://doi.org/10.1002/batt.202300404</p><p> </p><p>Specifically, the following measurements are provided in separate zip folders:</p><p>Solid polymer electrolytes characterization:</p><p>Differential Scanning Calorimetry ("DSC.zip")</p><p>Rheological measurements ("Rheology.zip")</p><p>Electrochemical Impedance Spectroscopy ("PEIS.zip")</p><p>Plating and Stripping Experiments ("Plating-Stripping.zip")</p><p>Galvanostatic Cycling with Potential Limitations (GCPL.zip)</p><p> </p><p>Experimental and sample details, including assignment to filenames are provided in the respective README files.</p&gt

Advanced Block Copolymer Design for Polymer Electrolytes: Prospects of Microphase Separation

Herein, we report on an advanced design for polymer electrolytes (PEs) based on our previously reported microphase-separated poly(vinyl benzyl methoxy poly(ethylene oxide) ether)-block-polystyrene block copolymers (PVBmPEO-b-PS). Usually, such block copolymers are characterized by a high mechanical stability provided by the PS domain, while the PEO-based domain features decent ionic conductivities, however, mostly only at higher temperatures. To enable suitable ionic conductivities at lower temperatures, we selectively implemented two ionic liquids (ILs) as a model plasticizer for the PEO domain. Since those ILs are nonmiscible with PS, the latter domain is unaffected, thus still providing a great mechanical stability. To maintain the necessary self-standing film forming ability, we adjusted the size of the PS domain to match with the conducting PEO-based domain. For this, a series of four block copolymers with different PS:PVBmPEO block ratios were synthesized, thus enabling the study of the influence of different amounts of IL. Further, all derived polymer electrolytes were thoroughly characterized by thermal, rheological, morphological, and electrochemical analyses. We could prove the microphase-separated morphology with long-range order and a good thermal and mechanical stability as well as the selective mixing of the ILs within the conducting domain. Consequently, electrochemical impedance spectroscopy revealed a significant increase in ionic conductivity up to 2 orders of magnitude and a reduced interfacial resistance in comparison to a nonplasticized reference sample. Moreover, exhaustive studies of the lithium-ion transference number showed not only the importance of such detailed analysis for IL-containing PEs but also the true increase of the effective lithium-ion conductivity. Finally, we conducted a full cycling in Li||LiFePO4 (LFP) cells to clearly demonstrate the applicability of our approach

Styrene-Based Poly(ethylene oxide) Side-Chain Block Copolymers as Solid Polymer Electrolytes for High-Voltage Lithium-Metal Batteries

Herein, we report the design of styrene-based poly(ethylene oxide) (PEO) side-chain block copolymers featuring a microphase separation and their application as solid polymer electrolytes in high-voltage lithium-metal batteries. A straightforward synthesis was established, overcoming typical drawbacks of PEO block copolymers prepared by anionic polymerization or ester-based PEO side-chain copolymers. Both the PEO side-chain length and the LiTFSI content were varied, and the underlying relationships were elucidated in view of polymer compositions with high ionic conductivity. Subsequently, a selected composition was subjected to further analyses, including phase-separated morphology, providing not only excellent self-standing films with intrinsic mechanical stability but also the ability to suppress lithium dendrite growth as well as good flexibility, wettability, and good contacts with the electrodes. Furthermore, good thermal and electrochemical stability was demonstrated. To do so, linear sweep and cyclic voltammetry, lithium plating/stripping tests, and galvanostatic overcharging using high-voltage cathodes were conducted, demonstrating stable lithium-metal interfaces and a high oxidative stability of around 4.75 V. Consequently, cycling of Li||NMC622 cells did not exhibit commonly observed rapid cell failure or voltage noise associated with PEO-based electrolytes in Li||NMC622 cells, attributed to the high mechanical stability. A comprehensive view is provided, highlighting that the combination of PEO and high-voltage cathodes is not impossible per se