Aromatic, microporous polymer networks with high surface area generated in Friedel-Crafts-type polycondensations

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A series of novel, microporous polymer networks (MPNs) have been generated in a simple, acid catalysed Friedel–Crafts-type self-condensation of A2B2- and A2B4-type fluorenone monomers. Two A2B4-type monomers with 2,7-bis(N,N-diphenylamino) A or 2,7-bis[4-(N,N-diphenylamino)phenyl] D substitution of the fluorenone cores lead to MPNs with high SBET surface areas of up to 1400 m2 g−1. Two MPNs made of binary monomer mixtures showed the highest Brunauer–Emmett–Teller (BET) surface areas SBET of our series (SBET of up to 1800 m2 g−1) after washing the powdery samples with supercritical carbon dioxide. Total pore volumes of up to 1.6 cm3 g−1 have been detected. It is observed that the substitution pattern of the monomers is strongly influencing the resulting physicochemical properties of the microporous polymer networks (MPNs)

Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The data were collected using the automated electron diffraction tomography (ADT) technique. The structure solution and refinement route is first validated on the basis of the known crystal structure of tri-p-benzamide. The same procedure is then applied to solve the previously unknown crystal structure of tetra-p-benzamide. In the crystal structure of tetra-p-benzamide, an unusual hydrogen-bonding scheme is realised; the hydrogen-bonding scheme is, however, in perfect agreement with solid-state NMR data

Cation‐Assisted Lithium Ion Transport for High Performance PEO‑based Ternary Solid Polymer Electrolytes

AbstractN‐alkyl‐N‐alkyl pyrrolidinium‐based ionic liquids (ILs) are promising candidates as non‐flammable plasticizers for lowering the operation temperature of poly(ethylene oxide) (PEO)‐based solid polymer electrolytes (SPEs), but they present limitations in terms of lithium‐ion transport, such as a much lower lithium transference number. Thus, a pyrrolidinium cation was prepared with an oligo(ethylene oxide) substituent with seven repeating units. We show, by a combination of experimental characterizations and simulations, that the cation's solvating properties allow faster lithium‐ion transport than alkyl‐substituted analogues when incorporated in SPEs. This proceeds not only by accelerating the conduction modes of PEO, but also by enabling new conduction modes linked to the solvation of lithium by a single IL cation. This, combined with favorable interfacial properties versus lithium metal, leads to significantly improved performance on lithium‐metal polymer batteries

Coordinating Anions “to the Rescue” of the Lithium Ion Mobility in Ternary Solid Polymer Electrolytes Plasticized With Ionic Liquids

Lithium salts with low coordinating anions such as bis(trifluoromethanesulfonyl)imide (TFSI) have been the state-of-the-art for polyethylene oxide (PEO)-based “dry” polymer electrolytes for 3 dec- ades. Plasticizing PEO with TFSI-based ionic liquids (ILs) to form ternary solid polymer electrolytes (TSPEs) increases conductivity and Li+ diffusivity. However, the Li+ transport mechanism is unaffected compared to their “dry” counterparts and is essentially coupled to the dynamics of the polymer host matrix, which limits Li+ transport improvement. Thus, a paradigm shift is hereby suggested: the utilization of more coordinating anions such as trifluo- romethanesulfonyl-N-cyanoamide (TFSAM), able to compete with PEO for Li+ solvation, to accelerate the Li+ transport and reach a higher Li+ transfer- ence number. The Li–TFSAM interaction in binary and ternary TFSAM-based electrolytes is probed by experimental methods and discussed in the context of recent computational results. In PEO-based TSPEs, TFSAM drastically accelerates the Li+ transport (increases Li+ transference number by a factor 6 and the Li+ conductivity by 2–3) and computer simulations reveal that lithium dynamics are effectively re-coupled from polymer to anion dynamics. Last, this concept of coordinating anions in TSPEs is successfully applied in LFP||Li metal cells leading to enhanced capacity retention (86% after 300 cycles) and an improved rate performance at 2C

Bond strength dependent superionic phase transformation in the solid solution series Cu_2ZnGeSe_(4-x)S_x

Recently, copper selenides have shown to be promising thermoelectric materials due to their possible superionic character resulting from mobile copper cations. Inspired by this recent development in the class of quaternary copper selenides we have focused on the structure-to-property relationships in the solid solution series Cu_2ZnGeSe_(4-x)S_x. The material exhibits an insulator-to-metal transition at higher temperatures, with a transition temperature dependent on the sulfur content. However, the lattice parameters show linear thermal expansion at elevated temperatures only and therefore no indication of a structural phase transformation. ^(63)Cu nuclear magnetic resonance shows clear indications of Cu located on at least two distinct sites, which eventually merge into one (apparent) site above the phase transformation. In this manuscript the temperature dependent lattice parameters and electronic properties of the solid solution Cu_2ZnGeSe_(4-x)S_x are reported in combination with ^(63)Cu NMR, and an attempt will be made to relate the nature of the electronic phase transformation to a superionic phase transformation and a changing covalent character of the lattice upon anion substitution in this class of materials

Coordination Polymers Based on [Cp*FeACHTUNGTRENUNG(h5-P5)]:\ud MAS NMR Studies

Slow diffusion reactions of the pentaphosphaferrocene ['CP AST'FE'('eta POT. 5-'P IND. 5')] ('CP AST'='eta POT. 5'- 'C IND. 5''ME IND. 5'. (1)) with 'CU'X (X='CL', 'BR', I) in different stoichiometric ratios and solvent mixtures result in the formation of one- and two-dimensional polymeric compounds 2-6 with molecular formula '[{'CU'('mü'-X)}-{'CP AST''FE'('mü IND.3','eta POT. 5':'eta POT. 1':'eta POT. 1'-'P IND. 5')}] IND. n' (X='CL' (2a), I (2'c)), '[{'CU'('mü'-I)}-{'CP AST''FE'('mü IND.3','eta POT. 5':'eta POT. 1':'eta POT. 1'-'P IND. 5')}] IND. n'(3), '[{'CU'('mü'-X)}-{'CP AST''FE'('mü IND.4','eta POT. 5':'eta POT. 1':'eta POT. 1'-'P IND. 5')}] IND. n' (X='CL' (4a), 'BR' (4b), I (4c), 'BR' (4'b), I (4'c)), '[{'CU IND.3''('mü'-I) IND. 2'('mü IND. 3'-I)}- {'CP AST''FE'('mü IND. 5','eta POT. 5':'eta POT. 1':'eta POT. 1':'eta POT. 1''P IND. 5')}] IND n' (5) and '[{'CU IND. 4''('mü'-X) IND. 4'(C'H IND. 3'CN)}- {'CP AST''FE'('mü IND. 7','eta POT. 5':'eta POT. 2':'eta POT. 1':'eta POT 1':'eta POT. 1'-'P IND. 5')}] IND n'(X='CL' (6a), 'BR' (6b)), respectively. The polymeric compounds have been characterised by single-crystal X-ray diffraction analyses and, for selected examples, by magic angle spinning (MAS) NMR spectroscopy. The solidstate structures demonstrate the versatile coordination modes of the cyclo-'P IND. 5' ligand of 1, extending from two to five coordinating phosphorus atoms in either 'sigma' or 'sigma'-and-'pi' fashion. In compounds 2a, 2'c and 3, two phosphorus atoms of 1 coordinate to copper atoms in a 1,2 coordination mode (2a, 2'c) and an unprecedented 1,3 coordination mode (3) to form one-dimensional polymers. Compounds 4a-c, 4'b, 4'c and 5 represent two-dimensional coordination polymers. In compounds 4, three phosphorus atoms coordinate to copper atoms in a 1,2,4 coordination mode, whereas in 5 the cyclo-'P IND. 5' ligand binds in an unprecedented 1,2,3,4 coordination mode. The crystal structures of 6a,b display a tilted tube, in which all P atoms of the cyclo-'P IND. 5' ligand are coordinated to copper atoms in 'sigma'- and 'pi'-bonding modes.Deutsche Forschungsgemeinschaft (projects Sche 384/26- 1 and Ec168/10, “Supramolecular Aggregations

Improving the NMC111∣ Polymer Electrolyte Interface by Cathode Composition and Processing

Despite significant improvements of polymer electrolyte properties, the interfaces towards the electrodes often yield high interfacial resistances due to poor contacts, which are bottlenecks for application of newly developed polymer, ceramic or composite electrolytes in lithium metal batteries (LMBs). Herein, the impact of processing as well as slurry composition of LiNi1/3Co1/3Mn1/3O2 (NMC111) based composite cathodes on the achievable electrochemical C-rate performance of LMBs based on quasi-solid single ion conducting polymer electrolytes (SIPE) is demonstrated. Composite cathodes with varying types and amounts of lithiated species are fabricated and systematically compared. Among all considered electrodes, cathodes with an addition of 5 wt% lithiated terephthalic acid (TA Li) yield the highest discharge capacity of 91 mAhg−1 at 1 C for Li metalmidSIPEmidNMC111 cells. Furthermore, similar cells operated with cathodes whose pores are impregnated with 5 wt% SIPE via drop/spin coating even provide a specific discharge capacity of 113 mAhg−1 at 1 C, thereby clearly highlighting the benefit of the selected processing strategy to realize cathodes with substantially improved charge carrier transport networks