Materials for sustainable energy production, storage, and conversion
A steadily growing human population and the growing global economy have led to a need to reduce CO2 emissions by using renewable energy sources such as solar, wind, biomass, geothermal, and water power with evergrowing interest in the fields of energy harvesting and storage seen during the past two decades. The harvesting of light is still a challenge, and solutions are needed to achieve both high efficiency and low cost electricity generation. While wind and sun are among the most powerful options for electricity generation in general, their intermittent nature makes large storage capacity necessary. Here, solutions are needed that are based either on chemical compounds, such as hydrogen or hydrocarbons, or on safe, low cost and powerful batteries, which have a long cycle and calendar life and a high energy density. For the reconversion of hydrogen or organic liquids efficient fuel cells are needed as converters. In addition to the harvesting and storage of electrical energy, the storage of heat is another essential element in the future energy landscape.
- Review
- Published 18 Aug 2014
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Figure 1: Schematic depicting a simplified image of metal–electrolyte interfaces for magnesium and lithium me...
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Figure 2: SEM images of the electrodeposited magnesium (a) 500×, 0.5 mA cm−2, (b) 500×, 1.0 mA cm−2, (c) 500×...
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Figure 3: For Sn anode: a) The first 10 cycles for a Mg2Sn (anode), Mo6S8 (cathode) in conventional and organ...
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Figure 4: Cyclic voltammogram for LiBH4 (0.6 M)/Mg(BH4)2 (0.18 M) in DME, (inset shows deposition/stripping c...
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Figure 5: Cyclic voltammograms of the Mg deposition/dissolution in 0.25 M THF solution containing as-prepared...
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Figure 6: a) X-ray crystal structure of 1-(1,7-C2B10H11) MgCl. Hydrogen atoms and THF carbon atoms are omitte...
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Figure 7: a) Crystal structure of Mg(BH4)(NH2). Atomic sizes are depicted by sphere radii. b) Mg zigzag struc...
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Figure 8: The OCV values of the test cells after constant voltage charge: positive electrode, (a) ordered Co3O...
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Figure 9: (a) Discharge curves of V2O5/carbon composites in the Mg(ClO4)2/acetonitrile electrolyte solution a...
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Figure 10: (a) Charge–discharge curves of graphene-like MoS2 in the Mg(AlCl3Bu)2/tetrahydrofuran electrolyte s...
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Figure 11: (a) Charge–discharge curves of α-MnO2 in organohaloaluminate/tetrahydrofuran electrolyte solution. ...
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- Review
- Published 07 Jan 2015
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Figure 1: Illustration of the proton-conduction mechanisms of Nafion. Nafion polymer chains self-align into a...
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Figure 2: Illustration of the proton conducting mechanisms in phosphoric acid (Grotthuss mechanism). 'Excess'...
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Figure 3: Chemical structures of m-PBI (poly[2,2-(m-phenylene)-5,5-bibenzimidazole]) and AB-PBI (poly(2,5-ben...
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Figure 4: Doping process of an AB-PBI membrane in hot phosphoric acid at various temperatures. The weight inc...
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Figure 5: Conductivity of acid-doped PBI and Nafion as a function of humidity at various temperatures. Reprod...
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Figure 6: Interaction between PBI polymer host and phosphoric acid. Chemical structures of the proton transfe...
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Figure 7: Left: Schematic drawing of an electrocatalyst composed of Pt nanoparticles loaded on the PBIs-wrapp...
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Figure 8: Schematic diagram illustrating the difference in the amount of phosphoric acid migration from the d...
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Figure 9: (a) Raman spectra of pristine and phosphoric acid-doped PBI. (b) Ratio of relative intensities vers...
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Figure 10: (a) Schematic drawing of confocal Raman microscopy mapping. Confocal Raman maps of phosphoric-acid-...
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Figure 11: IR spectra of pristine and phosphoric-acid-doped PBI. Reprinted with permission from [29]. Copyright 19...
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Figure 12: The H2PO4− ion under C2ν and Cs symmetries. These are the most probable orientations of H2PO4− at l...
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Figure 13: (a) Coverage of different adsorbates on platinum by analyzing |POS| and |NEG| Δμ amplitudes at vari...
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Figure 14: Normalized radiographs of the cross section of the MEA at different current densities j: a) 0 mA·cm...
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Figure 15: Changes of the transmission through the MEA (grey values) compared to steady-state conditions at OC...
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Figure 16: 3D rendering of the X-ray microtomography data for the electrode cross section (a) coated electrode...
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Figure 17: Locally resolved current maps of (a) coated and (b) sprayed gas diffusion electrode measured with t...
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- Full Research Paper
- Published 20 Apr 2015
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Figure 1: Geometry used for the microscopic simulation. It consists of an anode (blue), a cathode (red) and c...
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Figure 2: Geometry for mesoscopic simulations with the porous-electrode model.
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Figure 3: Distribution of electrolyte concentration in dependence of position in through-plane direction at a...
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Figure 4: (a) Comparison of cell potential during charging simulations on micro- and meso-scale for the two b...
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Figure 5: Cut through the ellipsoid-based micro-geometry showing heat production at a normalized capacity of ...
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Figure 6: Heat production for ellipsoid-based micro-structure due to different heat sources. Thick lines show...
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Figure 7: (a) Spatial distribution of the overpotential in through-plane direction for the ellipsoid-based mi...
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Figure 8: Spatial variation of temperature in through-plane direction for the microscopic ellipsoid case.
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- Review
- Published 23 Apr 2015
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Figure 1: Theoretical and (estimated) practical energy densities of different rechargeable batteries: Pb–acid...
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Figure 2: Operating principles of (a) a lithium-ion battery, (b) a metal–oxygen battery (non-aqueous electrol...
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Figure 3: (a) The Li–O phase diagram. (b) The Na–O phase diagram. Figure redrawn based on [18] and [19].
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Figure 4: Matrix for classifying voltage profiles of metal–oxygen batteries. Type 1A is the ideal case. Frequ...
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Figure 5: DEMS analysis of Li/O2 cells with different electrolyte compositions, namely a mixture of propylene...
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Figure 6: Sketch by Thotiyl et al. illustrating their findings on the oxidation of the carbon electrode. At d...
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Figure 7: SEM image of toroidal Li2O2 nanoparticles on a carbon fiber (10 µm in diameter) that form as a disc...
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Figure 8: Illustration of TEMPO as a redox mediator (RM) in an Li/O2 cell reversibly catalyzing the Li2O2 oxi...
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Figure 9: Literature timeline of research papers on aprotic sodium–oxygen batteries (ranked after date of acc...
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Figure 10: Sketch of the first room temperature sodium–oxygen cell and its discharge and charge potentials dur...
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Figure 11: Discharge/charge curves (Type 1B) of a sodium–oxygen battery with NaO2 as discharge product. The ma...
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Figure 12: The thermodynamic landscape of (a) sodium– and (b) lithium–oxygen cells. All values are calculated ...
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Figure 13: Voltage hysteresis of different carbon materials for the cathode of a sodium oxygen cell (left), fi...
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Figure 14: Voltage profiles of Na/O2 cells under static gas atmosphere and flowing gas atmosphere (Type 1B/3B)...
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Figure 15: Literature overview on different studies of Na/O2 cells. The comparison shows the voltage profile o...
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Figure 16: (a) The Li–S phase diagram. (b) The Na–S phase diagram. Redrawn from references [129,130]. The Na–S phase di...
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Figure 17: Schematic illustration of the reduction processes at the negative electrode during discharge of a L...
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Figure 18: Schematic illustration of the polysulfide shuttle mechanism after Mikhaylik and Akridge [123]. Long poly...
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Figure 19: Typical voltage profile of a lithium/sulfur cell. A similar behavior can be expected for an analogo...
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Figure 20: Schematic diagram of the interconnected pore structure of mesoporous CMK-3 impregnated with sulfur ...
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Figure 21: Operando X-ray absorption near-edge spectroscopy (XANES) measurements (left) during first charge an...
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Figure 22: Literature timeline of research papers on room temperature Na/S8 batteries (ranked after date of ac...
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Figure 23: (a) First discharge–charge curve of a Na/S8 battery with liquid electrolyte at room temperature and...
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Figure 24: (a) Voltage profiles a of Na/S8 cells with a TEGDME-based electrolyte and a nanostructured carbon/s...
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Figure 25: Room temperature sodium–sulfur battery based on shallow cycling between sulfur and soluble long cha...
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Figure 26: Literature overview on different studies of Na/S8 cells with liquid electrolyte operating at room t...
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- Full Research Paper
- Published 07 Jul 2015
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Figure 1: Schematic overview of electrochemical equilibrium (a) in large bandwidth inorganic semiconductors a...
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Figure 2: Equivalent circuit for the one diode model. The diode, D, describes the part of the circuit that re...
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Figure 3: (a) Cross section of a simulated electron beam generation volume directly at the PCMO–STNO interfac...
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Figure 4: Temperature dependence of the J–V characteristics for the PCMO–STNO junction: (a) in a linear and (...
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Figure 5: (a) Illustration of the manual parameter identification method, (b) Comparison of the measured data...
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Figure 6: Overview of the temperature dependence of the extracted diode parameters for the two analysis metho...
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Figure 7: Determination of the energy barrier EB: (a) from the diode parameter analysis of the J–V characteri...
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Figure 8: Determination of the activation energy, EA,RS, for thermally activated hopping transport from the s...
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Figure 9: Determination of the activation energy, EA,RP, of the thermally activated hopping transport for the...
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Figure 10: Schematic band structure of a PCMO–STNO heterojunction (a) at zero bias, (b) in the forward directi...
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Figure 11: (a) Comparison of J–V curves from the least squares fit and exemplarily data at a temperature of 22...
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Figure 12: (a) Sketch of the sample geometry for the electrical measurements in the cryostat, and (b) sketch o...
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- Review
- Published 09 Jul 2015
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Figure 1: Classification of heat storage media.
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Figure 2: Heat capacity of Solar Salt in the liquid phase [3-9].
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Figure 3: Thermal conductivity of Solar Salt reported by several groups [8,10-14].
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Figure 4: Density of Solar Salt in the liquid state [9,16,17].
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Figure 5: Viscosity of Solar Salt [18,19].
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Figure 6: Temperature dependent equilibrium constant for alkali metal nitrates and alkaline metal nitrates.
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Figure 7: Relative decomposition temperature of nitrate vs position in the periodic table.
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Figure 8: Scheme of phase diagram with eutectic mixture.
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Figure 9: Schematic of the novel experimental method and apparatus to synthesize new salt mixtures.
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Figure 10: Density of NaNO3 [16,30-32].
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Figure 11: Thermal conductivity of NaNO3 in the liquid range [10,11,13,14,31,33].
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Figure 12: Phase diagram of KNO3–NaNO3 [34] and the phase dependent enthalpy increase during thermal charging of t...
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Figure 13: Specific enthalpy of fusion for the salt mixture KNO3–NaNO3 [35,38].
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- Review
- Published 31 Aug 2015
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Figure 1: Gravimetric and theoretical volumetric capacities of metals and complex hydrides compared with thos...
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Figure 2: Theoretical equilibrium potential for the MHx/Li cell vs Li+/Li0. a) For binary hydrides M = Y, La,...
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Figure 3: Potentials vs Li+/Li0 of MHx/Li cells (V) as a function of the mole fraction of Li (x) recorded bet...
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Figure 4: Potential profile and XRD patterns of MgH2 electrode at different stages of the conversion reaction...
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Figure 5: Potential profile and XRD patterns of MgH2 electrode at various stages of the conversion reaction. ...
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Figure 6: Potential profile of a MgH2 electrode at various stages of the conversion reaction. a) Evolution of...
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Figure 7: Summary of the dehydrogenation process of TiH2 electrode δ-TiH2−x (fcc): black triangles, TiH (fco)...
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Figure 8: Discharge curves for a) Mg2FeH6, b) Mg2CoH5 and c) Mg2NiH4 electrodes prepared by reactive grinding...
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Figure 9: In situ XRD patterns of a) Mg2FeH6, b) Mg2CoH5 and c) Mg2NiH4 and d) Mg2FeH6-10% Ct,z electrodes pr...
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Figure 10: The evolution of the potential (V) as a function of x (mole fraction of Li) for a MgH2 electrode pr...
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Figure 11: a) DSC traces of commercial MgH2 unground and ground for 20 h. b) Evolution of the potential (V) as...
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Figure 12: a) Evolution of the potential (V) as a function of x (mole fraction of Li) for a MgH2 electrode pre...
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Figure 13: a) Absorption and b) desorption kinetics at 350 °C for Mg–10%C10,320 composite (open squares): firs...
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Figure 14: Evolution of the potential (V) as a function of x (mole fraction of Li) for MgH2 electrodes cycled ...
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Figure 15: Graphite BET surface area (m2·g−1) and d(002) interlayer distance (Å) as a function of grinding tim...
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Figure 16: Thermodesorption of commercial MgH2 (black diamonds) and commercial MgH2 ground 4 h with 10% of Ct,z...
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Figure 17: Evolution of the potential (V) as a function of x (mole fraction of Li) for MgH2 electrodes cycled ...
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Figure 18: Evolution of the potential (V) as a function of x for a Li/MgH2 cell that was cycled down to 0.15 V...
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Figure 19: Capacities of a MgH2 electrode obtained after three absorptions of hydrogen and then ground for 4 h...
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Figure 20: Evolution of the potential (V) as a function of x (mole fraction of Li) for MgH2 electrodes cycled ...
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Figure 21: Electrochemical cycling performance for MgH2 composite electrodes: MgH2–18% Ct,z (black triangles),...
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Figure 22: Potential profile of a) TiH2 electrode ground for 5 h with 10% of Ct,z carbon b) Ti + 2LiH electrod...
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