Structural and electronic features of binary Li2S-P2S5 glasses

The atomic and electronic structures of binary Li 2 S-P 2 S 5 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 PS x polyhedral anions based on the Raman spectroscopic results is reflected in the glassy structures of the 67Li 2 S-33P 2 S 5 , 70Li 2 S-30P 2 S 5 and 75Li 2 S-25P 2 S 5 glasses and the plausible structures represent the lithium ion distributions around them. It is found that the edge sharing between PS x and LiS y polyhedra increases at a high Li 2 S content and the free volume around PS x polyhedra decreases. It is conjectured that Li + ions around the face of PS x 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 P 2 S 7 anions. The P 2 S 7 anions of the weak electrostatic repulsion would causes it to more strongly attract Li + ions than the PS 4 and P 2 S 6 anions and suppress the lithium ionic conduction. Thus, the control of the edge sharing between PS x and LiS y 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.