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While lithium-oxygen batteries offer a green method to power vehicles, the sluggish decomposition of lithium peroxide limits device performance. Here, the authors direct lithium peroxide formation into amorphous nanostructures to enable its facile decomposition and improve charging efficiency.

Energy storage by metal redox reactions sets strict limits on capacity in metal oxide cathode materials used in lithium-ion batteries. Here authors study stabilization of redox reactions at oxygen sites and demonstrate a cathode with a high reversible capacity enabled by the process.

FCP-COMPLEX is a newly developed solution containing fluoride, calcium, and phosphoric acid that has the potential to reinforce caries-affected dentin. This study evaluated the effect of FCP-COMPLEX on micro-tensile bond strength (µTBS) and acid-challenge at the dentin-adhesive interface. FCP-COMPLEX, 2% NaF, and distilled water were applied to artificial caries-affected dentin (ACAD) and the effect on acid-induced damage after resin composite restoration was observed. Scanning electron microscopy and X-ray absorption fine structure (XAFS) were used to evaluate tooth morphology. The µTBS test revealed no effect of FCP-COMPLEX either immediately or after 3 months' storage. The area of acid damage in caries-affected dentin was reduced by FCP-COMPLEX. XAFS analysis revealed that absorbed fluorine on the surface would form CaF2. In conclusion, FCP-COMPLEX significantly reduced the damage of acidic attack at the ACAD-adhesive interface, while the µTBS value was maintained after storage. [ABSTRACT FROM AUTHOR]

The influence of the operating voltage range on the high-voltage charge/discharge characteristics of layered rock-salt positive electrode materials was investigated. The discharge capacity retention of LiNi1/3Co1/3Mn1/3O2 significantly improved as the discharge cutoff voltage (Vdc) increased. The polarization due to an increase in charge transfer resistance (Rct) was substantially increased by charge-discharge cycling of LiNi1/3Co1/3Mn1/3O2 with lower Vdc. In contrast, the increases in polarization and Rct were significantly suppressed when cycling with higher Vdc. The increase in Rct is caused by increased activation energy (Ea) of Li-ion transfer reaction at the electrode/electrolyte interface. An electrochemically inert Ni-O structure, which increases Ea and Rct, was observed at the surface of the LiNi1/3Co1/3Mn1/3O2 cycled with 2.5-4.6 V. The formation of the Ni-O structure was suppressed at the surface during cycling with 4.2-4.6 V. It was also confirmed that the observed dependence of the capacity retention, polarization, and Rct on the operating voltage range is basically common to LiCoO2 and LiNi0.81Co0.15Al0.04O2. The electrode/electrolyte interface with low Li-ion transfer resistance is stably retained when the charge/discharge voltage is limited to the high-voltage region only. [ABSTRACT FROM AUTHOR]

We have examined the local 3d electronic structures of Co-Au multinuclear complexes with the medicinal molecules D-penicillaminate (D-pen) [Co{Au(PPh3)(D-pen)}2]ClO4 and [Co3{Au3(tdme)(D-pen)3}2] by Co L2,3-edge soft X-ray absorption (XAS) spectroscopy, where PPh3 denotes triphenylphosphine and tdme stands for 1,1,1-tris[(diphenylphosphino) methyl]ethane. The Co L2,3-edge XAS spectra indicate the localized ionic 3d electronic states in both materials. The experimental spectra are well explained by spectral simulation for a localized Co ion under ligand fields with the full multiplet theory, which verifies that the ions are in the low-spin Co3+ state in the former compound and in the high-spin Co2+ state in the latter. [ABSTRACT FROM AUTHOR]

New sulfur-carbon composite positive electrode materials were synthesized through sulfurizing primary alcohols, and their electrochemical properties were examined. The sulfurized alcohol composites (SACs) showed relatively higher sulfur contents (more than 60 wt%) and were revealed to be an amorphous structure by high-resolution TEM observations. Raman and XAFS spectra showed the presence of S - S, C - S, and C - C bonds, and the C - C bonds mainly consisted of sp3 components, which makes a clear contrast to the previously reported organosulfur materials where the C - C bonds mainly consisted of sp2 components. The SAC positive electrode cells showed discharge capacities of more than 900 mAh·g-1 with relatively reduced cycle degradation. [ABSTRACT FROM AUTHOR]