We investigated the reversible charge compensation mechanism of an Li2MnO3 electrode using soft XAS analysis. We concluded that both the Mn and O ions participated in the charge compensation reactions during the reversible redox cycles.

The atomic and electronic structures of binary Li2S-P2S5 glasses used as solid electrolytes are modeled by a combination of density functional theory (DFT) and reverse Monte Carlo (RMC) simulation using synchrotron X-ray diffraction, neutron diffraction, and Raman spectroscopy data. The ratio of PSx polyhedral anions based on the Raman spectroscopic results is reflected in the glassy structures of the 67Li2S-33P2S5, 70Li2S-30P2S5, and 75Li2S-25P2S5 glasses, and the plausible structures represent the lithium ion distributions around them. It is found that the edge sharing between PSx and LiSy polyhedra increases at a high Li2S content, and the free volume around PSx polyhedra decreases. It is conjectured that Li+ ions around the face of PSx polyhedra are clearly affected by the polarization of anions. The electronic structure of the DFT/RMC model suggests that the electron transfer between the P ion and the bridging sulfur (BS) ion weakens the positive charge of the P ion in the P2S7 anions. The P2S7 anions of the weak electrostatic repulsion would causes it to more strongly attract Li+ ions than the PS4 and P2S6 anions, and suppress the lithium ionic conduction. Thus, the control of the edge sharing between PSx and LiSy polyhedra without the electron transfer between the P ion and the BS ion is expected to facilitate lithium ionic conduction in the above solid electrolytes.

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We have reported the 25Mg triple-quantum magic-angle spinning (3QMAS) NMR spectra of silicate glasses. The two-dimensional spectra suggest that the magnesium ions in MgSiO3, CaMgSi2O6, Ca2MgSi2O7, Mg3Al2Si3O12, and Li2MgSi2O6 glasses are mainly in octahedral environments, although in Na2MgSi2O6, K2MgSi2O6, and K2MgSi5O12 glasses they form tetrahedral species. We discussed the coordination environments of Mg based on the field strength of competing Mg2+, Ca2+, Na+, K+, and Li+ cations, and convincingly demonstrated that there is a correlation between them. These results indicate that the two-dimensional NMR spectroscopy such as MQMAS technique is a very useful method to analyze the local environments of nonframework cations in noncrystalline solids.

The layered-to-spinel phase transformation in Li2MnO3 during the initial charge process occurs by a two-phase reaction process within a single particle.

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