FIRST-PRINCIPLES STUDY OF THE LI ADSORPTION ON VARIOUS CARBON HYBRID SYSTEMS A Dissertation Presented to The Academic Faculty by Wonsang Koh In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Physics Georgia Institute of Technology August 2011 FIRST-PRINCIPLES STUDY OF THE LI ADSORPTION ON VARIOUS CARBON HYBRID SYSTEMS Approved by: Dr. Seung Soon Jang, Advisor Dr. Harold Kim School of Materials Science and School of Physics Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Andrew Zangwill Dr. Meisha Shofner School of Physics School of Materials Science and Georgia Institute of Technology Engineering Georgia Institute of Technology Dr. Zhigang Jiang School of Physics Georgia Institute of Technology Date Approved: June 13, 2011 ACKNOWLEDGEMENTS First of all, I would like to thank Prof. Jang for his unlimited support throughout the pursuit of my Ph.D. degree. It has been my great honor to have him as my advisor. His encouragement and inspiration led me to complete this thesis work. In addition, I also would like to thank Prof. Zangwill, Prof. Shofner, Prof. Jiang and Prof. Kim for serving on my thesis committee. I appreciate their advice and support, which was invaluable to my degree completion. I also would like to acknowledge the members of the Computational Nanobio Technology (CNBT) group. I specially thanks to Dr. Ji Il Choi for his valuable advice and discussions. I would like to express my gratitude to Seung Geol Lee and Giuseppe Brunello for their technical support and valuable discussions. And I thank all the undergraduate students who have helped my research. I also appreciate all the friends in School of Physics, Dr. Dongjoo Lee, Dr. Bokwon Yoon and Dr. Seungjoo Nah. Especially, I would show my special thanks to my old friend Dr. Seong-O Choi and his family. He always encouraged me to get my Ph.D.degree and was my side whenever I encountered difficulties. In addition, I would like to say special appreciation to my parents and parents-in- law. For the long time, they always showed their endless love and trust and encouraged me to reach my goal. Especially, I want to show my appreciation and love to my wife, Hyun. Without her endless love, support, patience and trust, I could not finish my study. Finally, I dedicate my thesis to my grand-mother who has showed love for her entire life. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS iv LIST OF TABLES ix LIST OF FIGURES xi SUMMARY xix CHAPTER 1 INTRODUCTION 1 1.1 Renewable energy 1 1.2 Li ion battery system 1 1.3 Carbon nanotube, fullerene and graphene 4 1.4 Computational method 6 1.4.1 Ab initio methods 7 1.4.2 Density functional theory 7 2 THEORY 9 2.1 Density functional theory 9 2.1.1 The Schrödinger equation 9 2.1.2 The Hohenberg-Kohn theorem 10 2.1.3 The Kohn-Sham equation 13 2.1.4 Approximations to the exchange-correlation (XC) functionals 15 2.1.4.1 Local density approximation (LDA) 15 2.1.4.2 Generalized gradient approximation (GGA) 17 2.2 DFT-D 17 v 3 FIRST-PRINCIPLES STUDY OF LI ADSOPRTION ON CARBON NANOTUBE-FULLERENE HYBRID SYSTEM 22 3.1 Introduction 22 3.2 Computational methods 25 3.3 Dilute CNT-C60 hybrid system 27 3.3.1 Pure CNT-C60 hybrid system 27 3.3.2 Single Li atom on CNT-C60 hybrid system 32 3.3.3 Adsorption of two Li atoms on CNT-C60 hybrid system 41 3.3.4 Multiple Li atoms adsorbed on CNT-C60 hybrid system 46 3.3.5 Electronic properties of the CNT-C60 hybrid system 52 3.3.6 Conclusion 55 3.4 Condensed CNT-C60 hybrid system 57 3.4.1 Pure condensed CNT-C60 hybrid system 57 3.4.2. One Li atom on a condensed CNT-C60 hybrid system 59 3.4.3 Multiple Li atoms on a condensed CNT-C60 hybrid system 63 3.4.4 Conclusion 67 4 FIRST-PRINCIPLES STUDY OF LI ADSOPRTION ON CARBON NANOTUBE-FULLERENE NANOBUD SYSTEM 69 4.1 Introduction 69 4.2 Computational details 71 4.3 Dilute CNT-C60 nanobud system 72 4.3.1 Pure CNT-C60 nanobud systems 72 4.3.2 Single Li atom on a (5,5) CNT-C60 nanobud system 81 4.3.3 Multiple Li atoms adsorption on the (5,5) CNT-C60 84 4.3.4 Conclusion 92 4.4 Condensed phase of a (5,5) CNT-C60 nanobud system 93 vi 4.4.1 Pure condensed CNT-C60 hybrid system 93 4.4.2 Single Li atom on a condensed (5,5) CNT-C60 nanobud system 95 4.4.3 Multiple Li atoms on a condensed CNT-C60 hybrid system 99 4.4.4 Conclusion 104 5 FIRST-PRINCIPLES STUDY OF LI ADSOPRTION ON CARBON NANOTUBE-FULLERENE NANO-NETWORK SYSTEM 105 5.1 Introduction 105 5.2 Computational details 107 5.3 Results and discussion 107 5.3.1 Pure CNT-C60 nano-network system 107 5.3.2 Single Li atom on a CNT-C60 network system 112 5.3.3 Multiple Li atoms on a CNT-C60 network system 114 5.4. Conclusion 123 6 FIRST-PRINCIPLES STUDY OF LI ADSOPRTION ON CARBON GRAPHENE-FULLERENE HYBRID & NANOBUD SYSTEM 125 6.1 Introduction 125 6.2 Computational methods 127 6.3 Graphene-C60 hybrid and graphene-C60 nanobud systems in the dilute phase 129 6.3.1. Pure Graphene-C60 hybrid and graphene-C60 nanobud systems 129 6.3.2 Single Li atom on graphene-C60 hybrid and graphene-C60 nanobud systems 133 6.3.3 Multiple Li atom on graphene-C60 hybrid and graphene-C60 nanobud system 139 6.4 Graphene-C60 hybrid and nanobud systems in the condensed phase 152 6.4.1 Pure graphene-C60 hybrid and nanobud system in the condensed phase 152 vii 6.4.2 Single Li atom on the graphene-C60 hybrid and graphene-C60 nanobud system 153 6.4.3 Multiple Li atoms on graphene-C60 hybrid and graphene-C60 nanobud system 157 6.5. Conclusion 166 7 CONCLUSIONS 168 REFERENCES 172 viii LIST OF TABLES Page Table 3.1: The Li adsorption energy and charge distribution (Mulliken charge) of various CNT-C60 hybrid system .................................................................................................... 31 Table 3.2: Binding energy and charge distribution (Mulliken charge) of a Li atom system ........................................................................................................................................... 33 Table 3.3: The adsorption energy and charge distribution (Mulliken charge) of one-Li atom system ...................................................................................................................... 40 Table 3.4: Energy decomposition analysis for one-Li systems ....................................... 41 Table 3.5: The adsorption energy of two- Li aomts adsorption systems ......................... 44 Table 3.6: The adsorption energy of many Li adsorption systems .................................. 50 Table 3.7: The adsorption energy and charge distribution (Mulliken charge) of one-Li atom system on the condensed (5,5) CNT-C60 hybrid system .......................................... 62 Table 3.8: The adsorption energy of two- Li atoms adsorption systems on condensed (5,5 ) CNT-C60 hybrid system ........................................................................................... 65 Table 4.1: Binding energy and bond length of the each CNT-C60 nanobud systems ...... 75 Table 4.2: Band gap and charge distribution of the each CNT-C60 nanobud systems..... 80 Table 4.3: The adsorption energy, charge distribution (Mulliken charge) and band gap of one-Li atom on (5,5) CNT-C60 bud system (55bud) ......................................................... 83 Table 4.4: The Mulliken charge of the carbon atoms in the CNT-C60 junction without or with the Li atom on the (5,5)bud:hs nanobud system ....................................................... 84 Table 4.5: The adsorption energy of two-Li adsorption systems on the (5,5)bud ........... 87 Table 4.6: The adsorption energy and charge distribution (Mulliken charge) of one-Li atom on the condensed (5,5) CNT-C60 nanobud system................................................... 98 Table 4.7: The adsorption energy of many-Li atoms adsorption systems on condensed (5,5) CNT-C60 nanobud system ...................................................................................... 101 Table 5.1: Mulliken charge distribution and bond length in the nano-network system 108 Table 5.2: Young’s, bulk and shear modulus of the CNT-C60 systems (Unit: GPa) ..... 112 ix Table 5.3: The adsorption energy and charge distribution (Mulliken charge) of one-Li atom on the (5,5) CNT-C60 network system ................................................................... 115 Table 5.4: The adsorption energy of many Li adsorption systems on the (5,5) CNT-C60 network ........................................................................................................................... 119 Table 6.1: Binding energy, bond length, Mulliken charge and band gap of the graphene- C60 hybrid and bud system .............................................................................................. 129 Table 6.2: The adsorption energy and charge distribution (Mulliken charge) of one- Li atom on the graphene-C60 hybrid system ........................................................................ 135 Table 6.3: The adsorption energy and charge distribution (Mulliken charge) of one-Li atom on the graphene-C60 nanobud system .................................................................... 138 Table 6.4: The adsorption energy of two- Li aomts adsorption on the graphene-C60 hybrid system .................................................................................................................. 143 Table 6.5: The adsorption energy of two- Li aomts adsorption on the graphene-C60 nanobud system ............................................................................................................... 146 Table 6.6: The