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Department of Chemistry

Science A 229
University of Calgary
2500 University Dr NW
Calgary, AB T2N 1N4 Canada
T. 403.220.5341
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info@chem.ucalgary.ca

Dr. Stefan Adams, Department of Materials Science and Engineering, National University of Singapore

Date & Time:
May 30, 2017 | 11:00 am
Location:
EEEL 161

Title: Engineering of crystal structures for high power batteries

Abstract:
With increasing system scale, materials and processing costs become key performance indicators of energy storage systems along with cycle-life and energy density. In this situation electrochemically stable fast alkali-ion conductors (FIC) gain importance not only for all-solid-state-batteries but also as key components in large-scale battery concepts (metal-air, metal-sulfur, alkali-redox flow). This renders designing new and optimizing known FICs crucial in order to technically and commercially enable large-scale energy storage systems with high rate performance.

On the computational side, we extended the classical crystal chemical bond valence into an energy-scaled “bond valence site energy” approach1 to predict ion migration pathways as well as to conduct molecular dynamics simulations. Using this approach, we screened a wide range of compounds for their suitability as alkali ion conductors, analysed the ion transport mechanism and the influence of processing parameters on the mobility to identify design guidelines for materials with balanced conductivity and stability. As the ionic conductivity in mixed conductors controls the achievable rate performance of insertion electrode materials, we extended our combined ab initio and empirical bond valence analyses to alkali-ion cathode material structures.2 This revealed a simple structure property relationship permitting us to predict directly from the structure model the characteristic (dis)charge rate up to which a material can be expected to yield high capacity.

On the experimental side, we aim to establish rational ways to optimize the processing of solid electrolytes and mixed conducting electrode materials by in situ X-ray or neutron monitoring of the formation process.3 Thereby we can not only achieve phase pure high performance materials with well-controlled dopant contents in a cost and energy-efficient way, but provide deeper understanding of the formation mechanisms and kinetics of the desired phase as well as of potential impurities.

We tested our predictions by the realization of an all-solid-state sodium-ion battery with high rate performance at room temperature4 and of Li-air batteries (LABs).5,6 Protected Lithium anode systems for aqueous and hybrid Lithium-air batteries based on the optimized fast ion conductors exhibit stable cycling with high energy efficiencies.

References:
[1]    Adams S., “Practical Considerations in Determining Bond Valence Parameters.” in “Bond ValencesStructure and Bonding 158 (2014) pp. 91-128, Springer, Berlin Heidelberg; (b) Adams S, Prasada Rao R.; “Understanding Ionic Conduction and Energy Storage Materials with Bond-Valence-Based Methods; in “Bond ValencesStructure and Bonding 158 (2014) pp.129-159.
[2]    Wong L.L., Chen H, Adams S; Design of fast ion conducting cathode materials for grid-scale sodium-ion batteries;  Phys. Chem. Chem. Phys. 19 (2017) 7506-7523.
[3]    Prasada Rao R. et al.; “In situ neutron diffraction monitoring of Li7La3Zr2O12 formation: toward a rational synthesis of garnet solid electrolytes” Chem. Mater. 27 (2015) 2903.
[4]    Prasada Rao R., Chen H, Wong L.L., Adams S, Na3+xMxP1−xS4 (M = Ge4+, Ti4+, Sn4+) enables high rate all-solid-state Na-ion batteries; J. Mater. Chem. A 5 (2017) 3377 - 3388.
[5]    Safanama D., Adams S., High efficiency aqueous and hybrid lithium-air batteries enabled by Li1.5Al0.5Ge1.5(PO4)3 ceramic anode-protecting membranes; J. Power Sources 340 (2017) 294.
[6]    Zhu, Y.G. et al. Proton enhanced dynamic battery chemistry for aprotic lithium–oxygen batteries; Nature Comm. 8 (2017), 14308.

Department Contact: Dr. Venkataraman Thangadurai (403-210-8649; vthangad@ucalgary.ca)

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