Magnetodielectric Properties of Ordered Microstructured Polydimethylsiloxane-Based Magnetorheological Elastomer with Fe3O4@rGO Nanoparticles.

Magnetodielectric properties of prepared ordered microstructured polydimethylsiloxane-based magnetorheological elastomer with the Fe3O4@rGO (Fe3O4@rGO/PDMS-MRE) were investigated to expand the application of magnetorheological elastomer (MRE) in magnetic sensing fields by improving the magnetodielectric effect. Five types of Fe3O4@rGO electromagnetic biphasic composite particles were synthesized by the solvothermal method, and their characterization and magnetic properties were also tested. Microstructurally ordered Fe3O4@rGO/PDMS-MRE samples with different Fe3O4@rGO concentrations were obtained through the magnetic field orientation technique, an experimental platform for magnetodielectric properties was built, and the relative permittivity of the samples was tested under magnetic flux density from 0 to 500 mT. The results show when the ratio of modified Fe3O4 to GO reaches 10:1, the Fe3O4@rGO composite particles exhibit uniform distribution with a flaky structure and strong magnetic properties and have the best bonding effect of composite particles. The relative permittivity of Fe3O4@rGO/PDMS-MRE increases with the rise of Fe3O4@rGO concentration and applied magnetic flux density. The relative permittivity of Fe3O4@rGO/PDMS-MRE with Fe3O4@rGO concentration of 60 wt% reaches 12.934 under the action of 500 mT magnetic flux density, and the magnetodielectric effect is as high as 92.4%. A reasonable mechanism for improving the magnetodielectric effect of ordered microstructured Fe3O4@rGO/PDMS-MRE is proposed.

Thermal pyrolysis of Si@ZIF-67 into Si@N-doped CNTs towards highly stable lithium storage.

Silicon is attracting considerable attention as an active anode material for advanced lithium-ion batteries due to its ultrahigh theoretical capacity. However, the reversible utilization of silicon-based anode materials is still hindered by the rapid capacity decay, as a consequence of the huge volume change of silicon during cycling. Herein, we use a Co-zeolitic imidazole framework (ZIF-67) to prepare silicon-wrapped nitrogen-doped carbon nanotubes (Si@N-doped CNTs) by controllable thermal pyrolysis. The as-prepared nanocomposites can effectively prevent pulverization and accommodate volume fluctuations of silicon during cycling. It can deliver a highly reversible capacity of 1100 mAh g-1 even after 750 cycles at a current density of 1000 mA g-1. As confirmed by an in situ transmission electron microscopy experiment, the remarkable electrochemical performance of Si@N-doped CNTs is attributed to the high electronic conductivity and flexibility of cross-linked N-doped CNTs network as a cushion to mitigate the mechanical stress and volume expansion. Furthermore, a full cell consisting of Si@N-doped CNTs anode and LiFePO4 cathode delivers a high reversible capacity of 1264 mAh g-1 and exhibits good cycling stability (>85% capacity retention) over 140 cycles at 1/4 C (1 C = 4000 mA g-1) rate.