The use of solid-state electrolytes represents a promising technology for the next
generation of Li-ion batteries, offering improved safety, stability and energy
density. Research in this field focuses on the development of materials that
provide high ionic conductivity and stability across a wide temperature and
potential range. In this master thesis we have analysed polymer electrolytes
based on PEO-LiTFSI, composite electrolytes based on PEO-LiTFSI and Ta-
LLZO and ceramic electrolytes based on Ta-LLZO ceramics. Based on LSV
measurements, we found that composite electrolytes based on PEO-LiTFSI and
Ta-LLZO demonstrate improved voltage stability (5.5 V vs. Li/ Li+), which enables
the integration of composite electrolytes with high-voltage cathode materials.
Measurements of ionic conductivity using EIS revealed lower ionic conductivities
of the composite electrolytes compared to the polymer PEO-LiTFSI electrolyte
(3×10-4 S cm-1 and 2×10-3 S cm-1). Polymer and composite electrolytes were
analyzed in configurations with LFP and LTO using galvanostatic measurements,
and we found that composite electrolytes provide more stable performance than
the polymer electrolyte. Furthermore, as part of the thesis, we fabricated a
ceramic electrolyte and optimised the composition for the tape casting and
sintering process. The resulting ceramic membrane was analysed with XRD and
SEM.
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