Grigorii Lev Soloveichik

Battery Technologies for Large-Scale Stationary Energy Storage

In recent years, with the deployment of renewable energy sources, advances in electrified transportation, and development in smart grids, the markets for large-scale stationary energy storage have grown rapidly. Electrochemical energy storage methods are strong candidate solutions due to their high energy density, flexibility, and scalability. This review provides an overview of mature and emerging technologies for secondary and redox flow batteries. New developments in the chemistry of secondary and flow batteries as well as regenerative fuel cells are also considered. Advantages and disadvantages of current and prospective electrochemical energy storage options are discussed. The most promising technologies in the short term are high-temperature sodium batteries with β″-alumina electrolyte, lithium-ion batteries, and flow batteries. Regenerative fuel cells and lithium metal batteries with high energy density require further research to become practical.

Ammine Magnesium Borohydride Complex as a New Material for Hydrogen Storage: Structure and Properties of Mg(BH4)2·2NH3

The ammonia complex of magnesium borohydride Mg(BH4)2.2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2.6NH3 (II), which crystallizes in the cubic space group Fm3 m with unit cell parameter a=10.82(1) A and is isostructural to Mg(NH3) 6Cl2. We solved the structure of I that crystallizes in the orthorhombic space group Pcab with unit cell parameters a=17.4872(4) A, b=9.4132(2) A, c=8.7304(2) A, and Z=8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2.2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by N-H...H-B dihydrogen bonds. Complex I decomposes endothermically starting at 150 degrees C, with a maximum hydrogen release rate at 205 degrees C, which makes it competitive with ammonia borane BH 3NH3 as a hydrogen storage material.

Structure of Unsolvated Magnesium Borohydride Mg(BH4)2

We have determined the structures of two phases of unsolvated Mg(BH(4))(2), a material of interest for hydrogen storage. One or both phases can be obtained depending on the synthesis conditions. The first, a hexagonal phase with space group P6(1), is stable below 453 K. Upon heating above that temperature it transforms to an orthorhombic phase, with space group Fddd, stable to 613 K at which point it decomposes with hydrogen release. Both phases consist of complex networks of corner-sharing tetrahedra consisting of a central Mg atom and four BH(4) units. The high-temperature orthorhombic phase has a strong antisite disorder in the a lattice direction, which can be understood on the basis of atomic structure.

Reversible catalytic dehydrogenation of alcohols for energy storage

Significance Catalytic hydrogenation and dehydrogenation reactions are extremely important in organic chemistry and recently for energy storage in the form of chemical bonds. Although catalysts are known which catalyze both reactions, the rates and conditions required for the two are frequently very different due to the differences associated with the bonds to be activated (C–H/O–H/N–H and C = O/C = N/H–H). The use of a bifunctional catalyst would substantially simplify the design of processes related to energy storage. In this work, organometallic complexes of iron and iridium are shown to act as catalysts for reversible dehydrogenation of alcohols to carbonyl compounds. This finding opens a pathway to the development of catalysts for direct reversible electrochemical dehydrogenation of organic fuels in energy generation and storage reactions. Reversibility of a dehydrogenation/hydrogenation catalytic reaction has been an elusive target for homogeneous catalysis. In this report, reversible acceptorless dehydrogenation of secondary alcohols and diols on iron pincer complexes and reversible oxidative dehydrogenation of primary alcohols/reduction of aldehydes with separate transfer of protons and electrons on iridium complexes are shown. This reactivity suggests a strategy for the development of reversible fuel cell electrocatalysts for partial oxidation (dehydrogenation) of hydroxyl-containing fuels.

Liquid fuel cells.

Summary The advantages of liquid fuel cells (LFCs) over conventional hydrogen–oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

Aminosilicone Solvents for CO2 Capture

This work describes the first report of the use of an aminosilicone solvent mix for the capture of CO(2). To maintain a liquid state, a hydroxyether co-solvent was employed which allowed enhanced physisorption of CO(2) in the solvent mixture. Regeneration of the capture solvent system was demonstrated over 6 cycles and absorption isotherms indicate a 25-50 % increase in dynamic CO(2) capacity over 30 % MEA. In addition, proof of concept for continuous CO(2) absorption was verified. Additionally, modeling to predict heats of reaction of aminosilicone solvents with CO(2) was in good agreement with experimental results.

Unsolvated lanthanidocene hydrides and borohydrides. X-Ray crystal structure of [(η5-C5H3tBu2)2Ln(μ-H)]2 (Ln = Ce, Sm)

Abstract The treatment of lanthanidocene alumohydrides (Cp2″LnAlH4·L)2 having bulky cyclopentadienyl ligands C5H3tBU2 with an excess of triethylaminalane yields related unsolvated hydrides [(C5H3tBu2)2Ln(μ-H)]2 (Ln = Ce (I), Sm (II)). Complex II was also obtained by the redox reaction of Cp2″Sm·THF with AlH3·NEt3. Crystals of I are triclinic, P 1 , a = 10.741(2) A, b = 11.302(2) A, c = 12.425(2) A, α = 65.20(1)°, β = 73.93(1)°, γ = 89.69(1)°, Z = 2, R = 0.031, Rw = 0.034. Crystals of II are triclinic, P 1 , a = 10.723(2) A, b = 11.305(3) a, c = 12.28 α = 115.73(2)°, β = 105.15(2)°, γ = 90.43(12)°, Z = 2, R = 0.054, Rw = 0.057. Unlike the lanthanidocene alumohydrides the related borohydrides are resistant to Lewis bases and crystallize from donor solvents as unsolvated dimers (Cp2*LnBH4)2. For complex [(C5H3tBU2)2Sm(μ-BH4)]2 (VI) X-ray structural information is convenient with the presence of bridge [(μ3-H)2B (μ2-H)2] groups. Crystals of VI are rhombic, Pnaa, a = 24.448(4) A, b = 13.023(2) A, c = 17.218(3) A, Z = 8, R = 0.088, Rw = 0.084.

Alumohydride complex of yttrium with three-coordinated hydrogen atoms. The crystal and molecular structure of {[(η5-C5H5)2Y(μ3-H)][μ2-H)AlH2·OC4H8]}2

Abstract The structure of the “alumohydride” tetrahydrofuronate of yttrium bis(η 5 -cyclopentadienyl) was determined using X-ray analysis. The dimeric molecule involves the Cp 2 Y(μ 3 -H) 2 YCp 2 metallocycle, connected to the AlH 3 · THF groups via the μ 2 - and μ 3 -hydrogen atoms (Y-μ 3 -H 2.17, 2.23 A; Al-μ 3 -H 2.00 A). The Y, Al and O atoms, as well as the bridging H atoms, are situated within the bisector plane of the wedge-like sandwiches Cp 2 Y.

Combinatorial discovery of metal co-catalysts for the carbonylation of phenol

Abstract The palladium-catalyzed carbonylation of phenol to form diphenyl carbonate (DPC) requires the presence of a metal co-catalyst to catalyze the reoxidation of palladium from Pd 0 to Pd 2+ in the presence of oxygen. In this study, we utilize a high throughput screening (HTS) methodology to rapidly study the nature of the co-catalyst with an emphasis on combinations of metal co-catalysts that appear to work in a synergistic manner to increase palladium usage. Critical new developments were made in using a small-scale reactor in diffusion controlled systems. The HTS system is described along with the optimized catalyst packages that were determined. Additionally, the results from HTS were used to better elucidate the mechanism of this potentially important commercial reaction.

Structural chemistry of titanium and aluminium bimetallic hydride complexes: III. Synthesis, molecular structure and catalytic properties of [(η5-C5H5)2Ti(μ2-H)2Al(μ2-H)(η1:η5-C5H4)Ti(η5-C5H5)(μ2-H)]2·C6H5CH3☆

Abstract By decomposition of the complex [(η5-C5H5)2TiH2AlH2]2 · TMEDA in toluene, the complex [(η5-C5H5)2Ti(μ-H)2Al(μ,-H)(η1 : η5-C5H4)Ti(η5-C5H5)(μ-H)]2 · C6H5CH3 was obtained. It crystallized in a monoclinic lattice with the unit cell parameters a 11.753(5); b 15.701(7); c 23.95(1) A, β 99.24(4)°, space group P21/c, V 4363 A3, Z = 4, ϱcalcd 1.32 g/cm3. The compound proved to be polycyclic. Two four-membered , two six-membered Ti(μ-C 5 H 4 )Al(μ-H)Ti(μ-H ) and one eight-membered Ti(μ-H)Ti(μ-H)Al(μ-H)Al(μ-H ) cycles can be distinguished in its structure. All hydride hydrogens are the bridging atoms. The titanium atom framework represents two almost regular isosceles triangles, while taking into account the aluminium atoms produces a gull-like figure with the “gull wings” being linked with the bridging hydrogen atom. Feasible pathways for the formation of this compound are discussed. The complex was shown not to promote the hydrogenation reaction of 1-hexene in a hydrocarbon medium, whereas in THF medium the hydrogenation rate amounted to 8 mol H2/g-atom Ti · min after a certain induction period.