Charged Polymer-Coated Separators by Atmospheric Plasma-Induced Grafting for Lithium-Ion Batteries

A simple and fast method of atmospheric plasma-induced grafting was applied over a polyethylene membrane to enhance its performance as a separator for lithium-ion batteries. The process of grafting has formed a thin, durable, and uniform layer on the surface of the porous membrane. The charges of grafted polymers affected the performance of batteries in many ways besides the change of hydrophilicity. Negative charges in polymers improve the capacity retention of batteries and the uniformity of the SEI layer. On the other hand, the electrostatic attraction between different charges contributed to small increases of thermal stability and mechanical strength of separators. Polyampholyte was grafted by using the mixtures of monomers, and the composition of the grafted layer was optimized. The formation of stable uniform SEI layers and the marked improvement in capacity retention were observed in the full cell tests of the lithium battery with the polyampholyte-grafted separators when the polyampholyte has a negative net charge

Elucidation of Isomerization Pathways of a Single Azobenzene Derivative Using an STM

The predominant pathway for the isomerization between <i>cis</i>- and <i>trans</i>-azobenzeneseither (i) inversion by the bending of an NNC bond or (ii) rotation by the torsion of two phenyl ringscontinues to be a controversial topic. To elucidate each isomerization pathway, a strategically designed and synthesized azobenzene derivative was investigated on a Ag(111) surface. This was achieved by exciting the molecule with tunneling electrons from the tip of a scanning tunneling microscope (STM). Structural analyses of the molecularly resolved STM images reveal that both inversion and rotation pathways are available for isomerization on a metal surface and strongly depend on the initial adsorption structures of the molecule. On the basis of the potential energy diagrams for the isomerization, it is concluded that isomerization pathways on a metal surface are not simply related to the excited states

Calix[4]tetrahydrothiophenopyrrole: A Ditopic Receptor Displaying a Split Personality for Ion Recognition

A calix[4]­pyrrole fused with 2,5-dihydrothiophene, possessing both a deep, π-electron-rich pocket upon anion binding and chelating ligands on the periphery, was developed. The receptor selectively forms an ion-pair complex with CsF through H-bonding and a cation−π interaction. In the process, it adopt a conformationally fixed cone conformation. The receptor displays exceptionally high affinity toward the Hg­(II) ion and forms stable complexes while maintaining a rigid 1,3-alternate conformation. This metal ion-induced conformational locking is unprecedented in calix[4]­pyrrole chemistry