Kyung Hee University,
Keywords: all-solid-state batteries, solid electrolytes, sulfide, casting, electrode fabrication
Summary:A potential solid electrolyte for realizing all-solid-state-battery (ASB) technology has been discovered in the form of Li10GeP2S12 (LGPS), a lithium superionic conductor with a high ionic conductivity (~12 mS cm-1). Unfortunately, the achievable Li+ conductivity of LGPS is limited in a sheet-type composite electrode, due to the porosity of this electrode structure. For the practical adoption of LGPS, it is crucial to control pore structures of the composite electrode, as well as the interfaces between active materials and solid electrolyte particles. Herein, we propose the addition of an ionic liquid, N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Py14TFSI), as a pore filler, for constructing a highly reliable electrode structure with LGPS. The Py14TFSI is coated onto the surface of LGPS powder via a wet process, and then a sheet-type composite electrode is prepared using a conventional casting process. The Py14TFSI-embedded composite electrode exhibits much improved reversible capacity and power characteristics. We suggest that pore-filling with Py14TFSI is effective in increasing contact areas and building robust interfaces between active materials and solid electrolyte particles, leading to the generation of additional Li+ pathways in the composite electrode of ASBs.