Solid State Electrolytes for Energy Storage and Conversion Devices
Abstract
Electrochemical energy conversion and storage devices hold significant importance in the
successful implementation of renewable energy systems. Solid-state electrolytes, with
garnet-type crystal structure for lithium ion batteries, have been synthesized using ceramic
method for energy storage application. A systematic study on lithium-stuffed garnet-type
Li5+2xLa3Ta2-xYxO12 (0.05 ≤ x ≤ 0.75) have been carried out for the understanding of the
effect of Y- and Li- doping on the structural, electrical, chemical and electrochemical
properties. Powder X-ray diffraction (PXRD) studies have revealed the cubic garnet-type
structure of the materials. The AC electrochemical impedance spectroscopy (EIS) has
shown that the sample with highest Li and Y content show the best Li+ ion conductivity of
10-4 Scm-1 at room temperature.
Optimization of lithium salt added during the solid-state preparation of garnets to
compensate lithium loss at higher sintering temperatures was also carried out on
Li6La3Ta1.5Y0.5O12. Crystal structure was unaltered with the change in lithium salt addition,
whereas the porosity and conductivity were affected. Evaluation of fundamental transport
properties of Li5+2xLa3M2-xYxO12 (M = Nb, Ta) (x = 0.25, 0.50 and 0.75) has been carried
out by employing AC EIS method. The dielectric analysis performed below room
temperature suggested that the Li+ ion conduction in garnet-type materials takes place
through a hopping mechanism following Path A (low energy route) or Path B (high energy
route).
Hybrid proton conducting materials derived from ionic liquid and
polyoxometalates have been developed for the potential application in energy conversion
devices. The effect of different heteropoly acids such as H3PW11MoO40, H4PMo11VO40 and H5PMo11V2O40 used along with (3-(pyridin-1-ium-1-yl) propane-1-sulfonate (PyPs)) ionic
liquid on the properties of hybrid materials were studied. A high thermal stability up to ~
300 °C, electrochemical stability of ~ 3V, and ionic conductivity of 0.01 Scm-1 at 90 °C
were observed for the hybrid proton conductors. A soft-chemistry approach was proposed
for the synthesis of another class of proton conductors, from layered perovskites such as
KLaNb2O7 and K2La2Ti3O10, and an imidazolium based ionic liquid. PXRD, scanning
electron microscopy (SEM), and thermogravimetric analysis (TGA) were used to
understand the ion exchange chemistry.
Description
Keywords
Chemistry--Physical
Citation
Narayanan, S. (2016). Solid State Electrolytes for Energy Storage and Conversion Devices (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27823