title: Cation Mixing Properties toward Co Diffusion at the LiCoO2Cathode/Sulfide Electrolyte Interface in a Solid-State Battery.
abstract: All-solid-state Li-ion batteries (ASS-LIBs) are expected to be the next-generation battery, however, their large interfacial resistance hinders their widespread application. To understand and resolve the possible causes of this resistance, we examined mutual diffusion properties of the cation elements at LiCoO2(LCO) cathode/β-Li3PS4(LPS) solid electrolyte interface as a representative system as well as the effect of a LiNbO3buffer layer by first-principles calculations. Evaluating energies of exchanging ions between the cathode and the electrolyte, we found that the mixing of Co and P is energetically preferable to the unmixed states at the LCO/LPS interface. We also demonstrated that the interposition of the buffer layer suppresses such mixing because the exchange of Co and Nb is energetically unfavorable. Detailed analyses of the defect levels and the exchange energies by using the individual bulk crystals as well as the interfaces suggest that the lower interfacial states in the energy gap can make a major contribution to the stabilization of the Co ↔ P exchange, although the anion bonding preference of Co and P as well as the electrostatic interactions may have effects as well. Finally, the Co ↔ P exchanges induce interfacial Li sites with low chemical potentials, which enhance the growth of the Li depletion layer. These atomistic understandings can be meaningful for the development of ASS-LIBs with smaller interfacial resistances.
authors.forename: Jun
authors.initials: J
authors.lastname: Haruyama
authors.affiliation: Elements Strategy Initiative for Catalysts and Batteries, Kyoto University , Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan.|PRESTO, Japan Science and Technology Agency (JST) , 4-1-8 Honcho, Kawaguchi, Saitama 333-0012, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Sodeyama
authors.affiliation: Elements Strategy Initiative for Catalysts and Batteries, Kyoto University , Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan.
authors.forename: Yoshitaka
authors.identifier: 0000-0002-5532-6134
authors.initials: Y
authors.lastname: Tateyama
keywords: first-principles calculations; interfacial resistance; lithium ionic conductor; mutual diffusion; solid electrolyte