PS-5

We perform the electronic and optical properties of the Li6PS5Cl compound using first-principles calculation. The featured physical and chemical pictures and orbital hybridizations in all Li-S and P-S chemical bonds are clearly exhibited, such as the optimized geometry, the quasi-particle energy spectra, the band-decomposed charge densities, and the van Hove singularities in the density of states. Furthermore, the calculated results of the presence and absence of electron-hole interactions in optical responses are achieved successfully through the dielectric function, the energy loss functions, the absorption coefficients, and the reflectance spectra. The Li6PS5Cl compound can be useful for extensive applications in all-solid-state batteries and optoelectronic. Our theoretical investigation of Li6PS5Cl material will encourage further studies to fully comprehend the diverse phenomena for other emerging materials.

Understanding the chemical composition and morphological evolution of the solid electrolyte interphase (SEI) formed at the interface between the lithium metal electrode and an inorganic solid-state electrolyte is crucial for developing reliable all-solid-state lithium batteries. To better understand the interaction between these cell components, we carry out X-ray photoemission spectroscopy (XPS) measurements during lithium plating on the surface of a Li6PS5Cl solid-state electrolyte pellet using an electron beam. The analyses of the XPS data highlight the role of Li plating current density on the evolution of a uniform and ionically conductive (i.e., Li3P-rich) SEI capable of decreasing the electrode|solid electrolyte interfacial resistance. The XPS findings are validated via electrochemical impedance spectrsocopy measurements of all-solid-state lithium-based cells.

Solid-state batteries (SSBs) have received attention as a next-generation energy storage technology due to their potential to superior deliver energy density and safety compared to commercial Li-ion batteries. One of the main challenges limiting their practical implementation is the rapid capacity decay caused by the loss of contact between the cathode active material and the solid electrolyte upon cycling. Here, we use the promising high-voltage, low-cost LiNi0.5Mn1.5O4 (LNMO) as a model system to demonstrate the importance of the cathode microstructure in SSBs. We design Al2O3-coated LNMO particles with a hollow microstructure aimed at suppressing electrolyte decomposition, minimizing volume change during cycling, and shortening the Li diffusion pathway to achieve maximum cathode utilization. When cycled with a Li6PS5Cl solid electrolyte, we demonstrate a capacity retention above 70% after 100 cycles, with an active material loading of 27 mg cm-2 (2.2 mAh cm-2) at a current density of 0.8 mA cm-2.