Polyacrylonitrile/graphene (PAN/GNS) composites have been synthesized via an in situ polymerization method for the first time, which serve as a precursor to prepare a cathode material for high-rate rechargeable Li–S batteries. It is observed from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the PAN nanoparticles, less than 100 nm in size, are anchored on the surface of the GNS and this unique structure is maintained in the sulfur composite cathode material. The electrochemical properties of the pyrolyzed PAN-S/GNS (pPAN-S/GNS) composite cathode have been evaluated by cyclic voltammograms, galvanostatic discharge–charge cycling and electrochemical impedance spectroscopy. The results show that the pPAN-S/GNS nanocomposite, with a GNS content of ca. 4 wt.%, exhibits a reversible capacity of ca. 1500 mA hg⁻¹ _sulfur or 700 mA hg⁻¹ _composite in the first cycle, corresponding to a sulfur utilization of ca. 90%. The capacity retention is relatively stable at 0.1 C. Even up to 6 C, a competitive capacity of ca. 800 mA hg⁻¹ _sulfur is obtained. The superior performance of pPAN-S/GNS is attributed to the introduction of the GNS and the even composite structure. The GNS in the composite materials works as a three-dimensional (3-D) nano current collector, which could act not only as an electronically conductive matrix, but also as a framework to improve the electrochemical performance.

Recently, we have developed a boron based electrolyte system with outstanding electrochemical performance, formed through the reaction of tri(3,5-dimethylphenyl)borane (Mes₃B) and PhMgCl in THF, for rechargeable magnesium batteries. In this paper, the main components and equilibria of the unique boron based electrolyte solutions are identified by NMR, single-crystal XRD, etc. The results prove that the solutions contain various magnesium species, such as Mg₂Cl₃ ⁺, MgCl⁺, Ph₂Mg and the tetracoordinated boron anion [Mes₃BPh]⁻. Fluorescence spectra and Raman spectroscopy analyses indicate that the high anodic stability (ca. 3.5 V vs. Mg reference electrode (RE)) of the Mes₃B–(PhMgCl)₂ electrolyte is attributed to the non-covalent interactions between the anion [Mes₃BPh]⁻ and Ph₂Mg. Furthermore, the air sensitivity of the boron based electrolyte and its electrochemical stability on the different current collectors are studied. Finally, the reversible electrochemical process of Mg intercalation into a Mo₆S₈ cathode confirms that the boron based electrolyte could be practically used in rechargeable Mg battery systems.