New molten salt chemistry allows solar thermal energy to drive calcium oxide production without any carbon dioxide emission. This is accomplished in a one pot synthesis, and at lower projected cost than the existing cement industry process, which after power production, is the largest contributor to anthropogenic greenhouse gas emissions.
A critical roadblock toward practical Mg-based energy storage technologies is the lack of reversible electrolytes that are safe and electrochemically stable. Here, we report on high-performance electrolytes based on 1-ethyl-3-methylimidazolium chloride (EMImCl) doped with AlCl3 and highly amorphous δ-MgCl2 . The phase diagram of the electrolytes reveals the presence of four thermal transitions that strongly depend on salt content. High-level density functional theory (DFT)-based electronic structure calculations substantiate the structural and vibrational assignment of the coordination complexes. A 3D chloride-concatenated dynamic network model accounts for the outstanding redox behaviour and the electric and magnetic properties, providing insight into the conduction mechanism of the electrolytes. Mg anode cells assembled using the electrolytes were cyclically discharged at a high rate (35 mA g(-1) ), exhibiting an initial capacity of 80 mA h g(-1) and a steady-state voltage of 2.3 V.
A straightforward synthetic route to nano-VB 2 particles, via planetary ball milling of elemental vanadium and boride in a 1:2 equivalent ratio is presented. Variation of the mechanochemical synthesis milling speed and milling time is used to optimize this nano-VB 2 for use as a high capacity anode material with enhanced charge transfer and increase voltage. VB 2 releases, via electrochemical oxidation, an unusual 11 electrons per molecule at a favorable, highly level electrochemical potential. Coupled with an air cathode, this anode with volumetric and gravimetric capacity of 20.7 kAh/L and 4.1 kAh/kg, has energy density greater than that of gasoline.Higher energy density batteries are needed for applications ranging from consumer electronics, industrial, medical, military applications, to hybrid and electric vehicles. The quest for a long, uninterrupted power supply has focused on lithium-ion batteries for a number of years, but recently an alternative material, vanadium diboride (VB 2 ) has been introduced as a potential high capacity anode, with a VB 2 air battery (utilizing an air-O 2 cathode) shown to have an order of magnitude higher capacity than lithium-ion batteries. 1 In an unusual multiple electron process, each VB 2 releases up to eleven electrons at a level discharge potential, which does not exhibit separate voltage plateaus. While electrochemically recharging this eleven electron anode is challenging, 2 the system has been demonstrated to be chemically rechargeable. 1 Using the VB 2 air battery has a theoretical discharge potential of 1.55 V, as calculated 3 from the thermodynamic free energy of the cell reactants and products: 4,5 Anode :Cell :With a density of 5.10 kg/l, the 11 electron per molecule VB 2 oxidation reaction provides a theoretical intrinsic volumetric and gravimetric capacity of 20.7 kAh/l and 4.1 kAh/kg and an intrinsic volumetric energy density of 32 kWh/l, which is higher than that of gasoline (∼10 kWh/l). Experimental discharge has yielded 3.7 kAh/kg to a 0.4 V discharge cutoff. 1 VB 2 corrodes at a slow rate in alkaline media, releasing hydrogen. However, we have demonstrated that a zirconia coating stabilizes VB 2 , when in contact with alkaline electrolytes, to minimize this self discharge reaction for alkaline batteries containing a VB 2 anode. 6,7 Traditionally, vanadium boride was prepared by high-temperature reaction of boron with metals, 8,9 or via carbothermal reduction of V 2 O 5 and B 2 O 3 above 1600 • C. 10 There have been a variety of other synthesis methods proposed for the formation of vanadium diboride, including a self-propagating high temperature synthesis from the elemental forms of vanadium and boron, 11 a nanocrystalline synthesis of VB 2 from the 650 • C solid state reaction VCl 4 , NaBH 4 and Mg, 12 as well as a mechanochemical procedure that utilized VCl 3 , LiH and LiBH 4 . 13 With the latter synthesis, VB 2 impurities prevent effective anodic discharge, but were sufficient to demonstrate that the nano-VB 2 yields higher open circuit potentials compar...
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