Current state and Prospects of Materials Science Research - Phdassistance
Functional Materials Lab Research Introduction
1. Dawei Liu
Assistant Professor of Materials Science and Engineering
Kazuo Inamori School of Engineering
Alfred University, NY
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2. PI bio
Dr. Dawei Liu received his BS degree from Department of Physics in
Nanjing University of China in 2004. From 2006 to 2010, he studied in
Department of Materials Science and Engineering at University of
Washington and obtained his Ph.D. degree in 2010. He was a postdoc
research associate in the same research group at the University of
Washington from 2010 to 2011 before moving to Brown University as a
postdoc research associate. He is now assistant professor of materials
science and engineering in Kazuo Inamori School of Engineering at Alfred
University.
Dr. Liu’s research focus includes surface modified materials for
electrochemical energy storage application and biosensor
research, mechanical property studies of oxide thin film as Li-ion battery
electrodes and fuel cell electrolyte. He has published more than 30 peer-
reviewed papers.
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3. Energy storage long-term goal
Nanostructured materials behave well in improving both the energy
density and power density in lab experiments
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4. Functional nanostructured oxides
Solution based route to fabricate homogeneous nanostructured
oxide film: low cost and high productivity
MnO2 nanowall arrays TiO2 nanotube arrays
Liu et al. Adv. Funct. Mater. 2009, 19, 1015 Liu et al. Electrochimi Acta 2009, 54, 6816
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5. Nanostructured electrodes
Wang et. al. Adv. Funct. Mater. 2006, 16, 1133
Nanostructured electrodes have larger surface area, shorter
lithium diffusion path and free volume change and
demonstrate high specific energy and specific power specific
power improved 1-2 order of magnitude 5
6. Nanostructure disadvantages
Angel in lab Hazard on the road
Nanostructured electrodes instability in long-term cycling at high
temperatures: capacity degradation and safety issues
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7. Surface chemistry engineering
Atomic layer deposition, vacuum or special gas annealing
Liu et al. J. Vac. Sci. technol. A 2012, 30, 01A123
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8. Enhanced energy storage capability
After surface chemistry engineering
Before surface chemistry engineering
Enhanced cyclic stability, especially at elevated temperature.
Liu et al. J. Phys. Chem. C 2011, 115, 4959
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9. Bio-sensors application
Nanostructured oxides as electrodes to detect bio-hazards
Improved sensitivity after surface chemistry engineering!
Zhang et al. J. Mater. Chem. 2009, 19, 948
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10. In situ stress investigation of thin film electrodes
Testing in situ stress development of film electrodes at ambient or elevated temperatures
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11. Key lab facilities
1. HT and LT battery testing system: Mbraun lab-star glove box, Arbin 32-channel battery tester
and Espec thermal chamber (-50 °C to 180 °C)
2. Electrochemical Biosensor testing : CHI6015E Electrochemical Analyzer
3. In situ stress investigation system: KSA Multi-beam Optical Stress Sensor (MOS)
4. Equipment for materials synthesis, processing and thermal treatment
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Ideal energy storage device should possess both high energy density and high power density. Lithium ion batteries have proved to be the most favorable candidate among all the energy storage devices after nanostructured electrodes were used.
Solution based synthesis routes are our expertise, including electrochemical deposition, electrophoretic deposition, hydrothermal growth, anodic oxidation, sol-gel route, etc. In addition to different nanostructures, we can also fabricate micro-meter sized films for energy storage and biosensor application.
Despite the great success in lab experiments, nanostructured lithium ion batteries are still experiencing a hard time in finding its commercialization. Safety issue is one of the problems due to the high surface energy of nanostructured electrodes which could cause excessive lithium plating; another more important challenge is the stability of nanostructured electrodes in long-term cycling which is also associated with the instability of nanostructure surface. If these problems could be solved, the market of lithium ion batteries will experience huge expansion.
Surface chemistry engineering is the most critical step before these nanostructured electrodes are used for lithium ion batteries. Nanostructure surface will be modified to make sure that it will be stable during the repeated lithium ion reactions. Various techniques could be used for this purpose: atomic layer deposition, plasma process, vacuum or special gas annealing, etc.
We have observed noticeable cyclic stability improvement after surface chemistry engineering. This improvement will be even more impressive at elevated temperatures due to the increased surface stability as compared with electrodes without surface chemistry engineering.
In addition to energy storage use, surface chemistry engineered nanostructures have proved to be favorable electrodes for biosensors application. Better absorption capability and much enhanced conductivity significantly improves the sensing ability.
Stress development inside the battery electrode is of critical importance to electrode performance. In situ stress measurement of thin films on quartz substrate as lithium ion battery electrodes are carried out by multi-beam optical stress sensor. Lithium ion intercalation will induce thin film volume expansion and bend the substrate; stress is converted by measuring the curvature change of quartz substate.
Nanostructured electrodes with modified surface chemistry will make commercialization of high-performance energy storage devices and biosensors much faster and more safe.
Appropriately fabricated nanostructured electrodes with modified surface chemistry will move steps far more close to commercialization of lithium ion batteries with high energy and power density and biosensors with greatly enhanced detecting properties.
