Characterization of Next Generation Lithium-ion Battery Materials Through Electrochemical, Spectroscopic, and Neutron-Based Methods DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Danny Xin Liu Graduate Program in Chemistry The Ohio State University 2015 Dissertation Committee: Anne C. Co, Advisor Prabir K. Dutta Sherwin J. Singer Harris P. Kagan Copyright by Danny Xin Liu 2015 Abstract The development of a real-time quantification of Li transport using a non-destructive neutron method to measure the Li distribution upon charge and discharge in a Li-ion cell is reported here. Using in situ neutron depth profiling (NDP), we probed the onset of lithiation in high capacity Sn and Al anodes and visualized the enrichment of Li atoms on the surface which is followed by their propagation into the bulk. The de-lithiation process shows the removal of near surface Li, leading to a loss in coulombic efficiency assigned to trapped Li within the intermetallic material. In situ NDP developed in this work provides temporal and spatial measurement of Li transport within the battery material with exceptional sensitivity. Direct application of Fick’s Laws allowed for the effective lithium diffusion coefficient to be calculated from the lithium concentration profiles. This diagnostic tool opens up possibilities of understanding rates of Li transport and their distribution to guide materials development for efficient storage mechanisms. In addition, in situ NDP was employed to explore the feasibility of utilizing Al as the anode current collector. The results indicate that an Al anode current collector can be employed as a strategy to improve energy density while reducing cost, provided that the surface of the Al is not in direct contact with Li+ or the voltage is limited to a value above the Al lithiation redox voltage. Our observations provide important mechanistic insights to the design of advanced battery materials. ii Dedication This document is dedicated to my family. iii Acknowledgments I am very grateful to The Ohio State University (OSU) and the Department of Chemistry and Biochemistry for the resources and opportunity to pursue a doctoral degree. I am especially indebted to my advisor, Professor Anne C. Co, and my colleagues within the Co Research Group for their patience, support, and guidance throughout my time at OSU. Prof. Co has been an influential mentor establishing an environment which fosters independent thought, innovative approaches, and collaborative strategies to address relevant technical challenges. I am very fortunate to have worked with Dr. Jennifer M. Black and Dr. Eric J. Coleman – two outstanding scientists that I consider dear friends. Of the numerous Faculty members that have contributed towards my development as a scientist. I would like to thank Prof. Prabir K. Dutta for teaching the Advanced Analytical Chemistry course – that provided the foundation upon which I have refined myself as an experimental scientist. I am forever indebted to Prof. Sherwin J. Singer for affording me the opportunity and support to develop as a physical chemistry student. I want to thank Prof. Walter R. Lempert, Prof. Heather C. Allen, and Prof. Sherwin J. Singer for serving as my First Year Oral Exam committee members. Additionally, I am grateful for the insights and critiques provided by my Candidacy Exam committee members, Prof. Prabir K. Dutta, Prof. Heather C. Allen, Prof. Yiying Wu. Finally, I iv would like to express my sincere gratitude to my Dissertation committee members listed on the title page. I have had the privilege of working with outstanding staff members within the Department Chemistry and Biochemistry. My teaching responsibilities have been primarily supervised by Dr. Steve Kroner. I thank Dr. Kroner for his guidance, support, and advice on countless academic, professional, and personal topics. I would like to acknowledge Jerry Hoff, Larry Antal, and Ryan Shea from the machine shop for their time, knowledge, and expertise in numerous projects and designs that have contributed towards my research efforts. I would like to thank Eric Jackson, Eric Kesselring, and John Sullivan from the electronics shop for sharing their knowledge in electronics and device fabrication. I want to thank Lisa Hommel for sharing her knowledge and experience in surface chemistry and training me on the operations of the x-ray photoelectron spectrometer (XPS). I would like to acknowledge Spencer Porter, Tricia Meyer, and Andrew Sharits for their maintenance and troubleshooting efforts regarding the x-ray diffractometer. Special thanks is reserved for the administrative staff especially Judy Brown, Jennifer Hambach, Kelly Burke and Thomas Hyle for organizing departmental events, disseminating crucial deadlines, and all of the necessary behind-the- scenes daily tasks and documentation that keep the department functional. Additionally, I would like to acknowledge Barbara Bennett (B2) from the computer support staff for her assistance during technical difficulties related to the computer network. I am grateful for the opportunities that resulted in collaborative relationships leading to many of the findings within this dissertation. Prof. Lei R. Cao and Dr. Jinghui v Wang have been instrumental collaborators who introduced me to the field of neutron depth profiling (NDP). Special recognition is reserved for Dr. R. Gregory Downing, a staff scientist at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). I thank Dr. Downing for his experience, insights, and patience throughout the collaborative experiments. Additionally, I have very grateful to have been granted access to the Cold NDP system at NCNR, which have led to pioneering findings and the advancement of in situ NDP within the energy storage community. The vast majority of my experience and knowledge of neutron depth profiling is a direct result of working with Dr. Downing. I would like to express my sincere appreciation to Rachelle L. Speth for her friendship, devotion, love and support throughout my graduate career. Returning her “misplaced” mitten was one of the best decisions I could have ever made. Finally, no words could express my gratitude for my parents. They have always encouraged me in my academic pursuits, challenged my rationalizations, provided guidance and supported me through turbulent times. They have had undeniably the greatest influence on my personal development and it is their experiences and insurmountable sacrifices that have shaped my outlook and afforded me the opportunities to pursue my dreams. I am and will forever be indebted to them. vi Vita 2004................................................................Woodbury High School 2008................................................................B.S. Chemistry, University of Minnesota – Twin Cities 2010 to present ..............................................Graduate Teaching/Research Associate, Department of Chemistry and Biochemistry, The Ohio State University Publications Liu, D.; Wang, J.; Ke, P.; Qiu, J.; Canova, M.; Cao, L.; Co, A. “In Situ Quantification and Visualization of Lithium Transport with Neutrons.” Angew. Chem. Int. Ed., 53 (2014) 9498-9502. Wang, J.; Liu, D.; Canova, M.; Downing, R. G.; Cao, L.; Co, A. “Profiling lithium distribution in Sn anode for lithium-ion batteries with neutrons.” J Radioanal Nucl Chem, 301, 1, (2014) 277-284. Tan, C.; Leung, K. Y.; Liu, D.; Canova, M.; Downing, R. G.; Co, A.; Cao, L. “Gamma radiation effects on Li-ion battery electrolyte in neutron depth profiling for lithium quantification.” J Radioanal Nucl Chem. 305, 2, (2015) 675-680. Fields of Study Major Field: Chemistry vii Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iii Acknowledgments.............................................................................................................. iv Vita .................................................................................................................................... vii Table of Contents ............................................................................................................. viii List of Tables ..................................................................................................................... xi List of Figures ................................................................................................................... xii Chapter 1. Introduction ................................................................................................... 1 Chapter 2. In Situ Quantification and Visualization of Lithium Transport with Neutrons ....................................................................................................................... 6 2.1. Introduction .......................................................................................................... 6 2.2. Neutron Depth Profiling ....................................................................................... 9 2.3. Methods .............................................................................................................. 11 2.4. Results and Discussion ......................................................................................