Spotlight


Dendrite Suppression to Curtail Lithium-Ion Battery Failure

posted Feb 16, 2013, 3:40 PM by R. Edwin García   [ updated Feb 17, 2013, 5:51 AM ]

Dr. David Ely and Prof. R. Edwin García have identified the different ways in which Li-ion batteries can develop dendrites during recharge. In their paper:

D. R. Ely and R. E. García "Heterogeneous Nucleation and Growth of Lithium Electrodeposits on Negative Electrodes." J. Electrochem. Soc. 160(4): A662-A668, 2013. doi: 10.1149/1.057304jes

the formation of these defects is of great importance because its nucleation precedes internal short-circuiting and even battery ignition. Fundamentally, the performed research proposes a Universal roadmap to allow experimentalists and theoreticians alike to explore the different regimes of behavior during battery recharge, and enables researchers to identify the conditions that will favor complete suppression (or at least minimization) of lithium aggregates. The work readily explains available in situ experimental data and reconciles conflicting existing theories as they were reported during the 1990s and early 2000s. While the developed theory is emphatically applied to Li-ion batteries, it was formulated so that it could be readily applied to other emerging battery chemistries, such as Mg- and S-ion batteries. 

Additional details can be found here 



dendrite master plot
Lithium dendrite formation map. Horizontal axis corresponds to battery charging state, and vertical axis corresponds to the initial size of the (lithium) deposit. Regimes of behavior during the initial stages of nucleation and growth are: 1) dendrite suppression, below the blue curve (improved battery life); 2) dendrite growth regime, above the black line (will lead to battery failure and ignition); 3) long incubation time regime, between the blue curve and the black curve (during battery storage and lasts from days to months); and finally, 4) short incubation time regime, in the vicinity of where the blue and black curves merge (during fast recharge rates). Continuous gray curves highlight charging states of constant dendrite incubation time. Dashed gray curves show the initial growth velocities of the stable nuclei. Inset (a) exemplifies a lithium dendrite internally short-circuiting a battery (micrograph courtesy of Dr. Quinn Horn).



Ozgur Keles selected to receive ACerS' Sapphire Award of Graduate Excellence

posted Nov 12, 2012, 1:13 PM by R. Edwin García   [ updated Nov 20, 2012, 7:27 PM ]

PhD student  Ozgur Keles was selected by the American Ceramic Society to receive the Sapphire Award in the Graduate Excellence in Materials Science (GEMS) award program. This award, presented annually by ACerS at the MS&T Conference is based on the scientific and academic accomplishment of the student, as well quality of research presented at the meeting and the overall oral presentation of the student.  He was selected for his paper "Statistical Failure Analysis of Crystallographically Isotropic Porous Materials", work he has done with his advisors R. Edwin Garcia and Keith J. Bowman, in the session on Multi Scale Modeling of Microstructure Deformation in Material Processing.
Ozgur Keles

Ozgur's and Tony's posters selected highlights at 2012 GRC in Solid State Studies in Ceramics

posted Nov 12, 2012, 1:09 PM by R. Edwin García   [ updated Nov 13, 2012, 8:18 PM ]

The posters presented by graduate students Ding-Wen (Tony) Chung (advisor: R. Edwin Garcia) and Ozgur Keles (co-advisors: R. Edwin Garcia and Keith Bowman) were selected as highlights of poster session A at the 2012 Gordon Research Conference in Solid State Studies in Ceramics.

Ozgur Keles' research focuses on the development of theories and models to describe the mechanical reliability of porous ceramics and thus establish correlations between continuum mechanics representations and statistical representations to describe mechanical failure.

Tony Chung's works on the development of microstructural design criteria to engineer rechargeable lithium-ion batteries to deliver higher power densities without sacrificing delivered energy density.

Ding-Wen (Tony) ChungOzgur Keles

Electrochemical Cycling Dynamics of Polycrystalline LiCoO2 Films

posted Nov 12, 2012, 1:05 PM by R. Edwin García   [ updated Nov 12, 2012, 1:41 PM ]

First-year MSE graduate student Tony Chung (R. Edwin Garcia, graduate advisor) has explored the underlying physics that govern a recently developed characterization technique, electrochemical strain microscopy (ESM), that utilizes the strong coupling between ionic current and anisotropic volumetric chemical expansion of lithium-ion electrode materials to dynamically probe the sub-one-hundred-nm interfacial kinetic intercalation properties. The performed analysis demonstrates that the local intercalation dynamics within a LiCoO2 thin film and the implications that such kinetics have on the macroscopic power density performance of currently used Lithium-ion batteries.
lithium cobalt oxide polycrystal

Lithium concentration distribution in crystallographically anisotropic LiCoO2 polycrystalline thin-film cathode layer (a) at different ESM overpotential values; (b) positive (battery discharge) and (c) negative (battery recharge) values. As the overpotential cycles, the lithium diffusion in and out of the film following a tortuous path, induces a volumetric chemical expansion/shrinkage that is captured by the ESM probe.

Stark Effect Suppression in (In,Ga)N Nanoheterostructures

posted Nov 12, 2012, 12:58 PM by R. Edwin García

(In,Ga)N nanostructures show great promise as the next generation LED technology. Its main advantage resides in the possibility of directly converting electrical energy into light without the use of down-converting phosphors. One of the most important challenges to realize the potential of this technology is to relax the high level of built-in electric field induced by the spontaneous and piezoelectric polarizations. Here, a research team that includes graduate students Zhiwen Liang, Isaac H. Wildeson, Robert Colby, and David A. Ewoldt, and Tong Zhang, as well as Professors Eric A. Stach, Timothy D. Sands, Bedrich Benes, and R. Edwin Garcia, has analyzed the benefits of Nanorods with pyramidal semipolar-oriented caps to supress the built-in electric field. Three-dimensional calculations performed on this structure demonstrate an order of magnitude reduction in electric fields, compared to the corresponding (traditional) thin film configuration. 

Stark effect minimization through nanorod engineering

Tony Chung Explores the Nanoscale Science of Rechargeable Battery Technology

posted Nov 12, 2012, 12:54 PM by R. Edwin García   [ updated Nov 12, 2012, 12:55 PM ]

Tony Chung, Purdue MSE BMSE 2011 (RE Garcia, advisor), has numerically simulated the intercalation of lithium at a spatial resolution below 100 nanometers in order to help explain the experiments performed ORNL and ISP (Ukraine). Here, AFM, FEM, and semi-analytical models are combined to analyze the local intercalation of single grains and grain boundaries during battery cycling. This basic science study sheds light into how the grain microstructure impacts the macroscopic power density of industrially used systems. The developed knowledge provides feedback to improve understanding of the nanoscale mechanisms underpinning lithium-ion battery operation.
schematic of Electrochemical Strain Microscopy

Freeing Gallium Nitride Nanorods from Dislocations

posted Nov 12, 2012, 12:50 PM by R. Edwin García

Wide band gap III-nitride semiconductors used in light emitting diodes (LEDs), such as GaN, have the potential to deliver high quality illumination at an unprecedented performances. However, current epitaxial growth methods and device designs lead to technologies with relatively low efficiencies, particularly in the green wavelength portion of the spectrum. Here, a research team that includes graduate students Robert Colby, Zhiwen Liang, Isaac H. Wildeson, and David A. Ewoldt and as well as Professors Eric A. Stach, R. Edwin Garcia, and Timothy D. Sands has developed a GaN-based nanostructure design that favors dislocation filtering by selective area growth through a nanoporous template. These nanorods grow epitaxially from the (0001)-oriented GaN underlayer through the ~100 nm thick template and naturally terminate with hexagonal pyramid-shaped caps. The work demonstrates that for a certain window of geometric parameters a threading dislocation growing within a GaN nanorod is likely to be excluded by the strong image forces of the nearby free surfaces. The developed LED structures constitute a promising technology to enhance the efficacy and device lifetimes of residential and portable lighting diodes as compared to conventional planar heterostructures.

Researchers on this work include Professors R. Edwin Garcia, Timothy D. Sands and Eric A. Stach and graduate students

Robert Colby, Zhiwen Liang, Isaac H. Wildeson, David A. Ewoldt

(a) Schematic of  nanorods.  Bright field (b) and weak beam dark field (c) TEM images.

(a) Schematic of fabricated nanorods, illustrating filtering by the template within the nanorod. Bright field (b) and weak beam dark field (c) TEM images show a typical dislocation terminating near the base of a 50 nm diameter nanorod. With similar filtering observed for all dislocations intersecting 50 nm pores, these nanorods can be said to be essentially threading dislocation free.

Group website has been created

posted Sep 15, 2009, 5:02 PM by R. Edwin García   [ updated Nov 27, 2011, 9:46 AM ]


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