Low Temperature Processing of Sulfide and Oxide Lithium Solid Electrolytes to Bridge Ionically Resistive Boundaries
Open Access
- Author:
- Berbano, Seth S
- Graduate Program:
- Materials Science and Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 05, 2016
- Committee Members:
- Michael T Lanagan, Dissertation Advisor/Co-Advisor
Clive A Randall, Committee Chair/Co-Chair
Donghai Wang, Committee Member
Susan E Trolier-Mckinstry, Committee Member
Dinesh Kumar Agrawal, Outside Member
Michael T Lanagan, Committee Chair/Co-Chair
Clive A Randall, Dissertation Advisor/Co-Advisor
Carlo G Pantano, Committee Member - Keywords:
- Ionic conductivity
Impedance spectroscopy
Lithium solid electrolyte
Grain boundary
Ceramic-polymer composites - Abstract:
- Solid electrolytes are enabling materials for solid-state batteries. The theme of the contributions in this thesis center around low temperature processing of solid electrolytes and their resulting microstructures and ionic conductivities. Solid electrolytes are of interest for safer and more reliable replacements to liquid electrolytes at a wide range of operating temperatures. Using pressure-temperature-assisted densification (200 oC and 190 MPa), ionically resistive pores were minimized and ionic conductivity was maximized in x Li2S + (1-x) P2S5 (x = 0.70, 0.75, 0.80) solid electrolytes. For 0.70 Li2S + 0.30 P2S5, the powder-in-a-tube method was demonstrated as a method to fabricate 120 μm thin electrolytes with 10-3 S/cm ionic conductivities at 25 oC for large area format batteries. Using cold sintering, the solid electrolyte Li1+xAlxGe2-x(PO4)3 (x = 0.50) was densified to around 80% theoretical density in minutes at 120 oC and 400 MPa. In order to bridge ionically resistive grain boundaries, a 5 minute post-processing at 650 oC was required. High volume fractions of ceramic electrolyte could be co-sintered with polymer. Up to 95 vol. % Li1.5Al0.5Ge1.5(PO4)3 + 5 vol. % Poly(vinylidene fluoride hexafluoropropylene) composite electrolytes were cold sintered at 120 oC to densities exceeding 85 %. After soaking in 1 M LiPF6 ethylene carbonate-dimethyl carbonate (50:50 vol. %), composite electrolyte ionic conductivities at 25 oC reached 10-4 S/cm. Using cold sintering, processing and integration of solid electrolytes and other important technical ceramics may now be possible at polymer processing temperatures.