1. Probing the Invisible in a High-Capacity Electrode Material for Lithium-ion Batteries  Rechargeable lithium-ion (Li-ion) batteries are currently evolving from applications in handheld electronic devices to use in electric vehicles.  Conventional lithium-ion systems are currently limited by their intercalation chemistry: the electrochemical reaction leading to energy storage is limited to insertion of Li electron per redox-active metal ion.  Studies carried out at an x-ray beamline at the U.S. Department of Energy’s Advanced Photon Source at Argonne National Laboratory researchers have shown that it is possible to improve energy capacity and storage densities required for more-efficient Li-ion batteries using a mixed-anion nanocomposite system involving both intercalation and conversion reactions. Advanced Photon Source, Argonne National Laboratory 1 Lithium storage mechanisms in a titanium hydroxyfluoride material. Damien Dambournet et al., J. Am. Chem. Soc. 133, 13240 (2011)

2. Imaging Chemical and Micro-/Nano-structural Features of Energy Materials in 3-D  Concerns about diminishing availability of petroleum reserves and effects of greenhouse gases on Earth’s climate have spurred intense efforts to develop cleaner alternative energy technologies such as solid oxide fuel cells (SOFCs).  These efforts have sparked interest in the reduction-oxidation (redox) cycling of nickel-based oxides in SOFC anodes, lithium-ion battery cathodes, and nickel oxide supercapacitors.  Monitoring redox cycling of such materials during system operation requires imaging and characterization changes at the chemical and morphological levels.  There are no standard nondestructive analytical techniques that enable the 3-D chemical imaging of complex and large architectures, but x-ray absorption near-edge structure (XANES) nanotomography is being developed to fulfill that need.  Full-field XANES nanotomography has been demonstrated at sub-30-nm spatial resolution by researchers utilizing beamlines at two U.S. Department of Energy Office of Science synchrotron light sources, including the Advanced Photon Source at Argonne National Laboratory. Advanced Photon Source, Argonne National Laboratory 2 Left: The distinction between Ni oxidation states is enabled by image subtraction at the energy levels associated with the primary features in the spectra. A linear combination of the Ni and NiO spectra, shown as the red dashed line, reproduces the spectrum for the region of overlapping Ni-NiO and corroborates the spectra obtained. Center: Transmission images were taken at x-ray energies of 8326 eV, 8334 eV, 8350 eV, and 8370 eV. Representative regions of each material (Ni (A), NiO (B), and overlapping Ni-NiO (C)) are indicated in the 8334-eV panel. Right: A region of interest highlighted in red in the upper-right image is tomographically reconstructed and segmented to identify the Ni and NiO phases. Images from Nelson et al., Appl. Phys. Lett. 98, 173109 (2011).

3. A Closer Look at Structural Changes in Dye-Sensitized Solar Cells  One limiting factor against the widespread use of solar-panel-based photovoltaics is obtaining cost-effective materials for commercially viable systems that can sustainably meet the modern demand for energy.  Most solar panels use solid-state, silicon-based solar cells but during the last decade a new technology using dye-sensitized solar cells (DSSCs) has proven to be more efficient and less costly.  By most estimates DSSCs will be capable of reaching grid parity — a break-even point of economic efficiency compared to electricity generated from conventional fossil fuels and distributed on the power grid.  In order to achieve workable DSSCs scientists and engineers must understand the structural functioning of these materials at the molecular level. Researchers using the U.S. Department of Energy’s Advanced Photon Source at Argonne National Laboratory have captured the transient structural changes in the excitation state of one DSSC, which will move us closer to new sources of economical and renewable energy. Advanced Photon Source, Argonne National Laboratory 3 Schematic of photoinduced interfacial electron transfer from RuN3 to TiO 2 nanoparticle, mimicking dye-sensitized solar cell. Xiaoyi Zhang et al., J. Phys. Chem. Lett. 2, 628 (2011).

4. Stacking Solar Cells  Photovoltaic devices that directly convert incident sunlight into electricity offer great potential as a sustainable, non-polluting energy source.  Chemists hope to find inexpensive alternatives to inorganic semiconducting materials, such as silicon, cadmium telluride, and copper indium gallium selenide.  Organic semiconducting polymers show much promise especially given that they are relatively easy to make, their properties can be fine-tuned and they can be flexible as well as inexpensive. Unfortunately, the efficiencies of organic, as opposed to inorganic semiconductors are not high.  Researchers using the U.S. Department of Energy’s Advanced Photon Source at Argonne National Laboratory have carried out studies that show how novel copolymers stack together to boost their solar energy conversion efficiency. Advanced Photon Source, Argonne National Laboratory 4 Feng He et al., J. Am. Chem. Soc. 133, 3284 (2011). Two-dimensional GIWAXS patterns of the blend films of PTAT-3/PC61BM (1:1, w/w) (a) and PTB-8/PC61BM (1:1, w/w) (b). (c) Out-of-plane linecuts of GIWAXS of PTAT-3/PC61BM and PTB-8/PC61BM films. (d) In-plane linecuts of GIWAXS of PTAT-3/PC61BM and PTB- 8/PC61BM films. Note: GIWAXS profiles have been shifted vertically for clarity. Feng He et al, ©2011 American Chemical Society.