It is widely accepted that increasing global energy demand should be met with renewable sources that do not contribute to the accumulation of greenhouse gases. Several abundant sources meeting these criteria, however, including solar and wind energy, are intermittent due to factors such as day/night cycles and weather variations. [ 1 ] This problem is amplifi ed by the poor match between peak/off-peak use of electricity and the generation capability of these renewable sources. Grid-scale strategies to mitigate these challenges, such as load-shifting, require energy storage components to supplement the current infrastructure, which comprises instantaneous generation and distribution of electricity. [ 2 ] Among several strategies for grid-scale energy storage, redox fl ow batteries (RFBs) are considered a promising technology. [ 3 ] In these systems, soluble, redox-active electrolytes are circulated between external storage tanks and current collectors. This approach has the benefi t of decoupling energy content and power output, both of which are independently scalable. [ 4,5 ] Aqueous RFBs are the current state-of-the-art, with commercial demonstration in place. [ 5 ] However these systems are limited to energy densities of ≈25 W h Kg −1 due to an open-circuit potential (OCP) that is bounded by water oxidation on one side and proton reduction on the other. [ 6,7 ] Further technical challenges include limited solubilities of electrolytes and narrow windows of temperature stabilities. [ 3 ] Non-aqueous systems, on the other hand, should allow for improved energy density due to the accessibility of much wider potential windows. Several such systems have been reported to date. [8][9][10][11] Nevertheless, the development of electrolytes with multiple, widely spaced redox events, and high solubility in organic solvents remains an important challenge.Herein we report details of a new, nonaqueous RFB electrolyte based on tetramethyl-and tetraethylammonium salts of tris(mnt)vanadium(IV) ([V(mnt) 3 ] 2− ; mnt = (NC) 2 C 2 S 2 2− ), 1a and 1b , respectively, including their battery performance in a static (i.e., non-fl owing) cell. The dithiolate moieties in this complex have been previously demonstrated to be redox noninnocent ligands (NIL), as they are known to participate in electrochemical events separate from those of the vanadium center to which they are bound. It was fi rst recognized through electron paramagnetic resonance spectroscopy in the 1960s that the singly occupied molecular orbital (MO) in [V(mnt) 3 ] 0 is ligand in character. [ 12 ] This fact was recently elaborated upon, whereby a suite of spectroscopic and computational methods unambiguously demonstrated that sequential one-electron reductions of [V(mnt) 3 ] 2− add electrons to the metal center, but one-electron oxidation removes an electron from the ligands, yielding an antiferromagnetically coupled, singlet-diradical ground state for [V(mnt) 3 ] 1− . [ 13 , 14 ] This ligand-based redox activity is a powerful approach to increasing the charge storage ...

Sea ice differs from fresh water ice in physical behavior because of the entrapment of liquid inclusions of brine in the ice matrix. This difference is strongly evident in the dielectric properties of the two ice forms. Pure ice is a low‐loss dielectric at frequencies above 107 Hz. Water, on the other hand, has its maximum loss at microwave frequencies. The liquid inclusions in sea ice, therefore, cause sea ice to be a lossy dielectric at microwave frequencies. The dielectric loss of sea ice at microwave frequencies is caused by two mechanisms, ionic conductivities and dipole rotations of the water molecules. The complex dielectric constant of sea ice was determined in the frequency range from 108 to 2.3×1010 Hz by measuring the changes in phase and amplitude when samples were placed in coaxial lines and waveguides. The measured values of the dielectric loss agree well with computations made using low‐frequency conductivity, brine volume, and salinity as known parameters.

Palladium and its alloys have high-value applications as materials for high-performance hydrogen storage, chromatographic separation of hydrogen isotopes, electrocatalysis and catalysis. These materials can be formed by chemical or electrochemical reduction in a lyotropic liquid crystalline template that constrains their growth on the nanometer scale. This approach works for a variety of metals, but Pd presents special challenges due to the autocatalytic nature of its growth, which can disrupt the template structure, resulting in disordered pores. Presented herein is a scaleable synthesis that overcomes these challenges, yielding mesoporous Pd powder having pore diameters of 7 or 13 nm. Pore size control is effected by varying the size of the molecular template, polystyrene-block-polyethylene oxide. We have used heated-stage TEM for in situ observation of the materials in vacuum and in the presence of H 2 gas, demonstrating that both pore diameter and the chemical state of the surface play important roles in determining thermal stability. Improved stability compared to previously reported examples facilitates preparation of scalable quantities of regularly mesoporous Pd that retains porosity at the elevated temperatures required for applications in hydrogen charge/discharge and catalysis.

With the cost of renewable energy near parity with fossil fuels, energy storage is paramount. We report a breakthrough on a bioinspired NRFB active-material, with greatly improved solubility, and place it in a predictive theoretical framework.