Showing posts with label shenoy. Show all posts
Showing posts with label shenoy. Show all posts

Brown University and University of Rhode Island Team Wins $6.17 Million DOE EPSCoR grant

Brown University and University of Rhode Island researchers led by principal investigator Pradeep R. Guduru, James R. Rice Associate Professor of Engineering at Brown, have won a three-year, $6.17 million grant from the Department of Energy (DOE) Experimental Program to Stimulate Competitive Research (EPSCoR). The project, “Fundamental Investigations of Mechanical and Chemical Degradation Mechanisms in Lithium Ion Battery Materials” will also involve Brown professors Allan Bower and Vivek Shenoy from the School of Engineering and Li-Qiong Wang from the Department of Chemistry; and Professors Brett Lucht, William Euler and Arijit Bose from the University of Rhode Island.
Electron microscopy images of the phase boundary between crystalline
silicon and amorphous lithiated silicon, revealing its atomic structure.
The sharp jumps in stress, composition and atomic structure across the
phase boundary play an important role in determining the mechanical
damage that results in silicon crystals during the initial charge cycle.

“This award represents a truly interdisciplinary research effort that brings together solid mechanics, chemistry and materials science,” said Guduru. “The research effort presents an opportunity for Brown and URI researchers to contribute to a technological area of national importance and forge strong collaborations with national labs and industry.”

“This new award contributes to the growing portfolio of engineering research at Brown in the energy and nanoscience fields,” said Dean Larry Larson. “These new fields are changing the way we live in thousands of different ways. Congratulations to all the faculty, post-docs, staff and students involved in these successful efforts.”

Electron microscopy images of the phase boundary between crystalline
silicon and amorphous lithiated silicon, revealing its atomic structure.
The sharp jumps in stress, composition and atomic structure across the
phase boundary play an important role in determining the mechanical
damage that results in silicon crystals during the initial charge cycle.



Despite the rapid advances in lithium ion battery (LIB) technology in recent years, major obstacles remain for vehicular applications of LIBs. It is widely recognized that further critical breakthroughs in the science and technology of lithium ion battery materials are necessary to develop the next generation of low-cost, long-life, higher energy density batteries for extended range electric vehicles.

The objective of the reserach funded under the DOE EPSCoR grant is to establish a comprehensive research program at Brown University and University of Rhode Island to develop fundamental and quantitative understanding of degradation mechanisms that limit the performance and cycle life of LIBs; and use the insights gained to help develop materials and architectures with significantly improved performance.

The research program encompasses critical challenges in the three major battery components: anodes, electrolytes and cathodes. Mechanical and chemical degradation of electrodes associated with large volume changes during charging and discharging is a critical factor that limits their capacity and lifetime. However, the degradation mechanisms are not well-understood quantitatively, which is a critical obstacle in developing the next generation of LIBs. The research team will address the fundamental issues of mechanical behavior & performance, controlling electrochemical side-reactions, formation and stability of solid-electrolyte interphase (SEI) layers. Through a combined experimental and computational approach, the team plans to develop the necessary quantitative understanding, which can help make battery materials design a well-controlled, principle-based process with predictable outcomes, in contrast to the largely trial and error based empirical approach being followed currently. The PIs will work with collaborators in national laboratories and battery industry in addressing the relevant problems of highest impact for developing the next generation of higher energy density battery systems.

Heat at the Borders

Brown University School of Engineering professor Vivek Shenoy's work on thermal transport across grain boundaries in graphene (published in Nano Letters last month) has also been featured in the research highlights section of Nature Materials. An abstract of his paper, "Thermal transport across Twin Grain Boundaries in Polycrystalline Graphene from Nonequilibrium Molecular Dynamics Simulations" follows:

Heat at the borders

Fabio Pulizzi
Nature Materials
 
10,
 
724
 
(2011)
Published online
 
Nano Letters http://dx.doi.org/10.1021/nl202118d (2011)

Graphene exhibits the highest thermal conductivity ever observed. Its thermal transport has been studied theoretically and experimentally, mostly in single-crystalline graphene. Unfortunately, large-scale growth, for example by chemical vapour deposition (CVD), usually yields polycrystalline sheets. Akbar Bagri and colleagues have performed molecular dynamic simulations of the thermal transport across various grain boundary orientations in graphene. They assumed a constant heat flow through the material, calculated the temperature profile and from that estimated the thermal conductivity. Interestingly, they found abrupt jumps in the temperature at the grain boundaries, which depend on the boundary orientation and grain size. The estimated grain boundary thermal conductivity is much higher than in the case of other materials with high thermal conductivity, such as nanocrystalline diamond. The results are particularly important in view of potential applications based on CVD-grown graphene. It will be interesting to see how the experiments will compare with these predictions.


For the full html version from NanoLetters, please go to:
http://pubs.acs.org/doi/full/10.1021/nl202118d
 
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