New insights into solvent-induced structural changes of C-13 labelled metal-organic frameworks by solid state NMR

Selective C-13-labelling of carboxylate carbons in the linker molecules of flexible metal-organic frameworks (MOFs) makes solid-state NMR spectroscopy very powerful to investigate solvent-induced local structural changes as demonstrated by C-13 and H-1 NMR spectroscopy on the pillared layer MOF DUT-8(Ni). Selective identification of polar solvent-node interactions becomes feasible

Mechanistic insights into the reversible lithium storage in an open porous carbon via metal cluster formation in all solid-state batteries

Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their highsloping capacity during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide derived carbon material (MPC) as promising future anode for all solid state batteries with a commercial high performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh g 1 carbon in half cells exhibiting an extended plateau region near 0 V vs. Li/Liþ preferable for full cell application. The well defined microporosity of the MPC with a specific surface area of >1500 m2 g 1 combines well with the argyrodite type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full cell measurements vs. nickel rich NMC cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76 V leading to a projected energy density as high as 449 Wh kg 1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex situ Small Angle X ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi metallic lithium clusters after electrochemical lithiation was revealed

Combining in situ techniques (XRD, IR, and 13CNMR^{13}C NMR) and gas adsorption measurements reveals CO2CO_2-induced structural transitions and high CO2/CH4CO_2/CH_4 selectivity for a flexible metal-organic framework JUK-8

[Image: see text] Flexible metal–organic frameworks (MOFs) are promising materials in gas-related technologies. Adjusting the material to processes requires understanding of the flexibility mechanism and its influence on the adsorption properties. Herein, we present the mechanistic understanding of CO(2)-induced pore-opening transitions of the water-stable MOF JUK-8 ([Zn(oba)(pip)](n), oba(2–) = 4,4′-oxybis(benzenedicarboxylate), pip = 4-pyridyl-functionalized benzene-1,3-dicarbohydrazide) as well as its potential applicability in gas purification. Detailed insights into the global structural transformation and subtle local MOF–adsorbate interactions are obtained by three in situ techniques (XRD, IR, and (13)CO(2)-NMR). These results are further supported by single-crystal X-ray diffraction (SC-XRD) analysis of the solvated and guest-free phases. High selectivity toward carbon dioxide derived from the single-gas adsorption experiments of CO(2) (195 and 298 K), Ar (84 K), O(2) (90 K)(,) N(2) (77 K), and CH(4) (298 K) is confirmed by high-pressure coadsorption experiments of the CO(2)/CH(4) (75:25 v/v) mixture at different temperatures (288, 293, and 298 K) and in situ NMR studies of the coadsorption of (13)CO(2)/(13)CH(4) (50:50 v/v; 195 K)

High-Capacity Reversible Lithium Storage in Defined Microporous Carbon Framework for All Solid-State Lithium Batteries

For decades graphite has been used as the anode material of choice for lithium batteries since porous carbons were believed to be inappropriate because of their high potential slope during lithiation as well as capacity losses due to intense formation of solid electrolyte interphase (SEI). However, in this work we demonstrate a microporous carbide-derived carbon material (HCmicro) to provide a high-capacity anode framework for lithium storage in all solid-state batteries. Half-cell measurements of HCmicro exhibit exceptionally high and reversible lithiation capacities of 1000 mAh g-1carbon utilizing an extremely long voltage plateau near 0 V vs. Li/Li+. The defined microporosity of the HCmicro combined well with the argyrodite-type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full-cell measurements vs. NMC-cathodes (LiNi0.9Co0.05Mn0.05O2) obtained a considerably improved average potential of 3.76 V leading to a projected energy density as high as 443 Wh kg-1. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex-situ Small Angle X-ray Scattering and further electrochemical investigations to elucidate the storage mechanism of lithium inside the carbon matrix revealing the formation of extended quasi-metallic lithium clusters

Adaptive Response of a Metal–organic Framework Through Reversible Disorder–disorder Transitions

A highly porous metal-organic framework (DUT-8(Ni), DUT = Dresden University of Technology) is found to adopt a configurationally-degenerate family of disordered states that respond adaptively to specific guest stimuli. This disorder originates from non-linear carboxylate linkers arranging paddlewheels in closed loops of different local symmetries that in turn propagate as tilings of characteristic complex superstructures. Solvent exchange stimulates the formation of distinct disordered superstructures for specific guest molecules. Electron diffraction by desolvated DUT-8(Ni) nanoparticles demonstrates these superstructures to persist on the nanodomain level. Remarkably, guest exchange stimulates reversible and repeatable switching transitions between distinct disorder states. Deuterium NMR spectroscopy and in situ PXRD studies identify the transformation mechanism as an adaptive singular transformation event.<br /