Lithium–sulfur (Li–S) batteries are considered as one of the most potential next‐generation rechargeable batteries due to their high theoretical energy density. However, some critical issues, such as low capacity, poor cycling stability, and safety concerns, must be solved before Li–S batteries can be used practically. During the past decade, tremendous efforts have been devoted to the design and synthesis of electrode materials. Benefiting from their tunable structural parameters, hollow porous carbon materials (HPCM) remarkably enhance the performances of both sulfur cathodes and lithium anodes, promoting the development of high‐performance Li–S batteries. Here, together with the templated synthesis of HPCM, recent progresses of Li–S batteries based on HPCM are reviewed. Several important issues in Li–S batteries, including sulfur loading, polysulfide entrapping, and Li metal protection, are discussed, followed by a summary on recent research on HPCM‐based sulfur cathodes, modified separators, and lithium anodes. After the discussion on emerging technical obstacles toward high‐energy Li–S batteries, prospects for the future directions of HPCM research in the field of Li–S batteries are also proposed.
The infrared photodissociation spectroscopy of mass-selected mononuclear iron carbonyl anions Fe(CO)(n)(-) (n = 2-8) were studied in the carbonyl stretching frequency region. The FeCO(-) anion does not fragment when excited with infrared light. Only a single IR active band was observed for the Fe(CO)(2)(-) and Fe(CO)(3)(-) anions, consistent with theoretical predictions that these complexes have linear D(∞h) and planar D(3h) symmetry, respectively. The Fe(CO)(4)(-) anion is the most intense peak in the mass spectra and was characterized to have a completed coordination sphere with high stability. Anion clusters larger than n = 4 were determined to involve a Fe(CO)(4)(-) core anion that is progressively solvated by external CO molecules. Three CO stretching vibrational fundamentals were observed for the Fe(CO)(4)(-) core anion, indicating that the Fe(CO)(4)(-) anion has a C(3v) structure. All the carbonyl stretching frequencies of the Fe(CO)(n)(-) anion complexes are red-shifted with respect to those of the corresponding neutrals.
Surfaces of sulfate-terminated polystyrene microspheres are anisotropically modified with silver nanoparticles covering 20-50% of the sphere surface using electroless deposition. A PDMS templating method is employed. Silver nanoparticles are found to deposit uniformly onto the exposed sphere surfaces. The deposition is diffusion-controlled and the nanoparticles adhere strongly to the polystyrene particles despite extensive exposure to ultrasonication. Silver content is confirmed by EDAX analysis. The final silver coverage is controlled via the PDMS pre-curing conditions.
We report nonintrusive optical microscopy measurements of single micrometer-sized silica and polystyrene colloids in inhomogeneous AC electric fields as a function of field amplitude and frequency. By using a Boltzmann inversion of the time-averaged sampling of single particles within inhomogeneous electric fields, we sensitively measure induced dipole-field interactions on the kT energy scale and fN force scale. Measurements are reported for frequencies when the particle polarizability is greater and less than the medium, as well as the crossover between these conditions when dipole-field interactions vanish. For all cases, the measured interactions are well-described by theoretical potentials by fitting a nondimensional induced dipole-field magnitude. While silica dipole-field magnitudes are well-described by existing electrokinetic models, the polystyrene results suggest an anomalously high surface conductance. Sensitive measurements of dipole-field interactions in this work provide a basis to understand dipole-dipole interactions in particle ensembles in the same measurement geometry in part II.
A titanium–oxo cluster-reinforced gel polymer electrolyte is developed to improve the performance of high-sulfur-loading lithium–sulfur batteries under lean electrolyte conditions.
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