Tape casting of oxide-ceramic electrolyte layers for all-solid-state lithium batteries

All-solid-state lithium batteries (ASB) have better safety properties due to the incombustible solid electrolyte than commercial lithium ion batteries (LIB), which use flammable organic liquid as electrolyte. Their compatibility with using high voltage cathode materials enables a higher energy density. Oxide-ceramic lithium ion conductors such as Li7La3Zr2O12 (LLZ) [1] have a good total ion conductivity of about 10 4 S cm-1 at room temperature [2]. The stability of LLZ when contacting lithium metal and its wide electrochemical stability window (usable up to 8V vs. Li/Li+) would provide higher energy densities than common LIB. In combination with its advantage of inertness in oxygen atmosphere, which simplifies their handling during materials processing, it is one of the most promising candidates for all-solid-state battery application. LLZ was synthesized via solid state reaction and spray pyrolysis. The structural stability and LLZ’s total ion conductivity were improved by substitution of Al [2], Ta [3] and Y [4] into the LLZ structure. Ta substituted LLZ indicated the highest total ionic conductivity of about 10-3 S cm-1 and almost no dependence on its lithium concentration. After investigation of bulk electrolyte materials, an ASB prototype cell using bulk LLZ as solid electrolyte was fabricated at IEK-1 and proved to run an LED. To meet the technical requirements of real battery systems, large size LLZ functional layers need to be fabricated by different established technologies. To bridge from lab works to application, the investigated LLZ has been processed by tape casting and was used for sintering studies, in order to obtain highly dense solid electrolyte layers and also mixed electrode films for prospective all-solid-state lithium batteries.References:[1] Murugan et al., Angew. Chem. Int. Ed. 46 (2007) 7778.[2] Hubaud et al., J. Mater. Chem. A. 1 (2013) 8813. [3] Buschmann et al., Phys. Chem. Chem. Phys. 13 (2011) 19378.[4] Murugan et. al., Electrochem. Commun. 13 (2011) 1373