Investigating the microscopic behavior of interfaces and crystal lattices

The graduate students I work with are involved in the study of the structure/property relationships of many different types of materials. Our past work has focused on the migration mechanisms of grain boundaries under stress, the shape stability of thin film surfaces, the properties of metal/ ceramic interfaces, corrosion and fracture at metal surfaces exposed to chemically active environments, interfacial fracture of nanograin and nanophase materials, and the reactions at metal/ metal and metal/semiconductor interfaces. More recently, we have been working on materials for use in advanced energy storage systems (batteries). It is evident that there are great economic and environmental concerns acting to drive the extremely rapid technological development for this type of light weight power source. The group has been collaborating with investigators from national labs, industry, and other universities on solving the important problems of materials degradation in rechargeable Li ion batteries. In particular, our studies have revolved around the cobalt and manganese lithium oxides. From a microstructural point of view, there are many unanswered questions about how and why these materials degrade during service. The major experimental tool employed during this research effort has been high resolution transmission electron imaging and convergent beam electron diffraction ( MTU microscopy).We have found this technique to be complimentary to the low resolution techniques of x-ray/neutron diffraction and electrochemical methods of analysis.

TEM lattice fringe image from Gamma MnO2 used in alkaline batteries.

One of the first students to graduate from the battery materials research group is Dr. Yang Shao-Horn. She was a very active scientist/engineer while at MTU, worked extremely hard and even recieved the Student Battery Research Award from the Electrochemistry Society while attending a conference in Paris, France (!). She initially took a position at Energizer, followed by a post-doc in France and is now an assistanat professor at MIT. Three other graduate have also produced research results in this group related to thin film batteries, defects in manganese oxides and new two dimensional structures for manganese oxide intercalation materials. Phil Jun is now an engineer at Gold Star, Thapanee Sarakonsri is an instructor at a University in Thailand, and Todd Bofinger is an engineer at Duracell.

The atomic structures of these battery materials are important, but I also find it fascinating the way the overall electrode macrostructure and cell discharge conditions affect the crystal microstructure. I think that there is a tremendous need to 'bridge the length scales' in this area. Although a difficult mathematical and experimental challenge, the examination of the point where crystal chemistry and electrochemical engineering meet has become one of my personal areas of interest.

Recent Archival Publications.

"Periodic Behavior in Surface Limited Grain Growth", S. A. Hackney, Scripta Met., 34, 1021 (1996).

"Nonlinear Effects in Surface Limited Grain Growth", S. A. Hackney, Scripta Met, 35. 29 (1996)

"Stabilized alpha-MnO2 Electrodes for Rechargeable 3 V Lithium Batteries", C. S. Johnson, M. F. Mansuetto, M. M. Thackeray, Y. Shao-Horn and S. A. Hackney, Journal of the Electrochemical Society, 144, 2279 (1997).

"Structural Characterization of HEMD and Topotactic Transformation of Discharge Products in the Li/MnO2 Cell", Y. Shao-Horn, S. A. Hackney and B. C. Cornilsen, ibid, 144, 3147 (1997).

"Morphology Modification and Delithiation Mechanisms of LiMn2O4 and Li2MnO3 by Acid Digestion", Y. Shao-Horn, S. A. Hackney, W. F. Howard, W. F. Averill, Y. Ein-Eli, and A. D. Robertson, ibid, 145, 16 (1998).

Microstructural Stability of Electrochemically Active Alpha MnO2 During Redox Synthesis and Li Intercalation", Y. Shao-Horn, S. A. Hackney, C. S. Johnson and M. M. Thackeray, ibid, 145, 582 (1998)

"Formation of Self-Assembled Quantum Wires ", X. Deng, Bi-Ke Yang, S. A. Hackney and M. Krishnamurthy, Phys. Rev. Letters, 80, 1022 (1998)

"Structural Features of Low-Temperature LiCoO₂ and Acid-Delithiated Products", Y. Shao-Horn, S.A. Hackney, C.S. Johnson, and M.M. Thackeray, J. Solid State Chemistry, 140, 116 (1998).

"Structural Fatigue in Spinel Electrodes in High Voltage (4V) Li-Li_xMn₂O₄ Cells", M.M. Thackeray, Y. Shao-Horn, A.J. Kahain, K.D. Kepler, E. Skinner, J.T. Vaughey, and S.A. Hackney, Electrochemical and Solid State Letters, 1, 7 (1998).

"Structural Characterization of Layered LiMnO₂ Electrodes by Electron Diffraction and Lattice Imaging", Y. Shao-Horn, S. A. Hackney, A. R. Armstrong, P. G. Bruce, R. Gitzendanner, C. S. Johnson and M. M. Thackeray, J. Electrochem. Soc. 146, 2404 (1999).

"Stabilization of Insertion Electrodes for Li Batteries", M.M. Thackeray, Y. Shao-Horn, A.J. Kahain, K.D. Kepler, J.T. Vaughey, and S.A. Hackney, J. Power Sources, 81, pp60-66 (1999).

Structural and Electrochemical Analysis of Layered Compounds from Li2MnO3", C. S. Johnson, M.M. Thackeray, Y. Shao-Horn, A.J. Kahain, K.D. Kepler, Todd Bofinger, J.T. Vaughey, and S.A. Hackney, J. Power Sources, 82, 491-496 (1999).

"Composite Electrodes for Li Ion Batteries.", M.M. Thackeray, C. S. Johnson,Y. Shao-Horn, A.J. Kahain, K.D. Kepler, E. Skinner, J.T. Vaughey, and S.A. Hackney, ITE Battery Letters, 1,1 (1999)

"Preferred Orientations of Polycrystalline LiCoO2 Films", J. B. Bates, N. J. Dudney, P. H. Jun, S. A. Hackney, Journal of the Electrochemical Society, vol. 147, 59 (2000).

"W. Bowden, R. Sirotina and S. A. Hackney, ITE Letters, 1, 903 (2000)

"On The Low Temperature Stability of LiCoO2", Y. Shao-Horn, S. A. Hackney, A. J. Kahaian, M. M. Thackeray, Journal of Solid State Chemistry, 168, pp 60-68, (2002)

"Lithiation of HEMD: NMR, XRD, TEM and Electrochemical Investigation of the Discharge Mechanism" W. Bowden, C. Grey, S. A. Hackney, X. Q. Yang, Y. Paik, F. Wang, T. Richards and R. Sirotina in "ITE Letters" vol. 3 no. 3, pages 312-336 (2002).

Other Recent Collaborators and Consulting Activities.

John Bates, ORNL

Radoslav Atanasoski, 3M

Larry Krause, 3M

Bill Bowden, Duracell

Danny Xiao, USNanocorp

Dan Branigan, INEEL

Bob Minck, USABC

Pierre Hovington, HydroQuebec

Martin Simoneau, HydroQuebec