Mg(PF6)2-based electrolytes for Mg-ion batteries have not received the same attention as the analogous LiPF6-based electrolytes used in most Li-ion cells owing to the perception that the PF6(-) anion decomposes on and passivates Mg electrodes. No synthesis of the Mg(PF6)2 salt has been reported, nor have its solutions been studied electrochemically. Here, we report the synthesis of the complex Mg(PF6)2(CH3CN)6 and its solution-state electrochemistry. Solutions of Mg(PF6)2(CH3CN)6 in CH3CN and CH3CN/THF mixtures exhibit high conductivities (up to 28 mS·cm(-1)) and electrochemical stability up to at least 4 V vs Mg on Al electrodes. Contrary to established perceptions, Mg electrodes are observed to remain electrochemically active when cycled in the presence of these Mg(PF6)2-based electrolytes, with no fluoride (i.e., MgF2) formed on the Mg surface. Stainless steel electrodes are found to corrode when cycled in the presence of Mg(PF6)2 solutions, but Al electrodes are passivated. The electrolytes have been used in a prototype Mg battery with a Mg anode and Chevrel (Mo3S4)-phase cathode.

For magnesium ion batteries (MIBs) to be used commercially, new cathodes must be developed that show stable reversible Mg intercalation. VS 4 is one such promising material, with vanadium and disulfide anions [S 2 ] 2− forming onedimensional linear chains, with a large interchain spacing (5.83 Å) enabling reversible Mg insertion. However, little is known about the details of the redox processes and structural transformations that occur upon Mg intercalation and deintercalation. Here, employing a suite of local structure characterization methods including X-ray photoelectron spectroscopy (XPS), V and S X-ray absorption nearedge spectroscopy (XANES), and 51 V Hahn echo and magic-angle turning with phase-adjusted sideband separation (MATPASS) NMR, we show that the reaction proceeds via internal electron transfer from V 4+ to [S 2 ] 2− , resulting in the simultaneous and coupled oxidation of V 4+ to V 5+ and reduction of [S 2 ] 2− to S 2− . We report the formation of a previously unknown intermediate in the Mg−V−S compositional space, Mg 3 V 2 S 8 , comprising [VS 4 ] 3− tetrahedral units, identified by using density functional theory coupled with an evolutionary structure-predicting algorithm. The structure is verified experimentally via X-ray pair distribution function analysis. The voltage associated with the competing conversion reaction to form MgS plus V metal directly is similar to that of intermediate formation, resulting in two competing reaction pathways. Partial reversibility is seen to re-form the V 5+ and S 2− containing intermediate on charging instead of VS 4 . This work showcases the possibility of developing a family of transition metal polychalcogenides functioning via coupled cationic−anionic redox processes as a potential way of achieving higher capacities for MIBs.

Conjugated polymers have emerged over the past several decades as key components for a range of applications, including semiconductors, molecular wires, sensors, light switchable transistors and OLEDs. Nevertheless, the construction of many such polymers, especially highly substituted variants, typically involves a multistep synthesis. This can limit the ability to both access and tune polymer structures for desired properties. Here we show an alternative approach to synthesize conjugated materials: a metal-catalysed multicomponent polymerization. This reaction assembles multiple monomer units into a new polymer containing reactive 1,3-dipoles, which can be modified using cycloaddition reactions. In addition to the synthetic ease of this approach, its modularity allows easy adaptation to incorporate a range of desired substituents, all via one-pot reactions.

Bi nanowires as anode materials for Mg ion batteries exhibit excellent electrochemical behaviour, forming MgBi; this is in part ascribed to the rapid Mg mobility between the two Mg sites of MgBi, as revealed by the Mg NMR spectra of MgBi formed electrochemically and via ball-milling. A mechanism involving hops into vacant Mg sites is proposed.

We report the first examples of thiocyanate-based analogues of the cyanide Prussian blue compounds, MIII[Bi(SCN)6], M= Fe, Cr, Sc. These compounds adopt the primitive cubic pcu topology and show strict cation order. Optical absorption measurements show these compounds have band gaps within the visible and near IR region, suggesting that they may be useful for photocatalytic applications. We also show that Cr[Bi(SCN)6] can reversibly uptake water into its framework structure pointing towards the possibility of using these frameworks for host/guest chemistry.<br>