Growth of LiCoO2 and Li4Ti5O12 Crystals in Lithium Ion Conductive Li2.2C0.75B0.25O3 glass for All-Solid-State Libs

Abstract

All-solid-state lithium ion rechargeable batteries (LIBs) consisting of solid electrolytes have been desired for higher energy density, long term durability and safety. A great challenge of all-solid-state LIBs for practical use is reduction of the interfacial resistance. Effective interface modification techniques have been proposed, however, the interfacial resistance is still large because the charge transfer resistance at the active material/ solid electrolyte interface would be strongly affected by interfacial contact condition. Herein, we propose a new route to prepare smart interfaces for all-solid-state lithium ion batteries via the direct growth of electrode active material crystals in Li ion conductive glass. Co3O4, Li2CO3, and Li3BO3 were used as a starting materials for LiCoO2 crystal growth in Li2-xC1-x+yBxO3+2y glass matrix. The volume fraction of LiCoO2 crystal was controlled to be >80% toward the glass matrix. The mixed powders was heated at designated temperature for 1 min to 5 h. Subsequently the powders were cooled to 500°C under temperature controlled conditions. The as obtained composites were structurally characterized by XRD, SEM-EDS, XRD, and TEM. All diffraction lines were in agreement with the ICDD data for LiCoO2. Since the diffraction lines of Li2CO3, and Li3BO3 were not observed, Li2-xC1-x+yBxO3+2y formed amorphous. SEM revealed the idiomorphic LiCoO2 crystal having barreled shape were homogeneously dispersed in the glass flax. Furthermore, the interface was atomically connected without any sub-phases formation, evaluated by TEM, suggesting that the interfaces provide seamless Li+ transportation pathways. Growth of Li4Ti5O12 crystals and futher electrochemical characteristics of these active material crystals will present in the ECS 227th Meeting.