Fabrication of solid electrolyte for Li ion batteries and its electrochemical properties

다국어 초록 (Multilingual Abstract)

The rechargeable lithium ion batteries (LIBs) are moved from the negative electrode to the positive electrode during discharge and back when charging. Lithium ion batteries are one of the most popular types of rechargeable batteries for portable electrochemical energy conversion and storage devices, such as video/audio players, medical equipment, power tools, meters and data loggers, remote sensors, electronic vehicles, and aerospace applications because of higher energy density than other commercialized rechargeable batteries, no memory effect, and only a slow loss of charge when not in use. The commercial lithium ion batteries have four kinds of main components such as a cathode (positive electrode), anode (negative electrode), electrolyte (organic liquid with ionic conduction), and separator. Generally, the negative electrode of a conventional lithium-ion cell is made from carbon. The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. The cathode materials are required for capacity and safety. The anode materials are required for capacity and life time, and the electrolyte materials are required for safety and reliability. However, commercial lithium ion batteries are a risk of explosion and environmental pollution because lithium ion batteries use an organic liquid electrolyte. Solid-state lithium ion batteries have the potential to achieve higher energy density with better safety than conventional liquid-based lithium batteries. Therefore, the all solid state lithium ion batteries with solid electrolyte are proposed as a new strategy for lithium ion batteries with high safety. In this dissertation, three kinds of electrolytes such as ceramic solid electrolyte, flexible ceramic-polymer composite electrolyte and gum-like ceramic-polymer composite electrolyte have been investigated as a means for applying lithium ion battery. First, the influence of the processing parameters such as synthesis temperature and lithium sources on the structure, particle size, morphology and ionic conductivity of the Li1.3Ti1.7Al0.3(PO4)3 (LTAPO) was investigated. LiNO3, LiCl, and Li acetate were employed as lithium sources for investigating the effects of Li sources on the properties of solid electrolyte. Second, flexible ceramic-polymer composite electrolyte consisting of LTAPO ceramic powder, polytetrafluoroethylene (PTFE) polymer with/without liquid electrolyte was fabricated by mixing and rolling. The effect of the liquid electrolyte on the ionic conductivity of the prepared ceramic-polymer electrolyte was investigated. Finally, this part was investigated on the fabrication of a gum-like ceramic-polymer composite electrolyte with lithium salts, consisting of LTAPO ceramic powder, poly(ethylene oxide) (PEO) polymer and lithium salts such as lithium chloride (LiCl), lithium perchlorate (LiClO4), and lithium perchlorate trihydrate (LiClO4?3H2O). LiCl, LiClO4, and LiClO4?3H2O were employed as main lithium ion contributor for investigating the effects of lithium salt on the properties of gum-like composite electrolyte. Several properties, such as morphology, phase analysis, average particle size and distribution of LTAPO powders, electrochemical impedance spectroscopy (EIS), ionic conductivity, and electrochemical performance were measured for each electrolyte. Properties of each electrolyte were confirmed through these evaluations.

목차 (Table of Contents)

• CONTENTS
• ABSTRACT ---------------------------------------------------------------------------i
• CONTENTS -------------------------------------------------------------------------iv
• LIST OF TABLES ----------------------------------------------------------------viii
• LIST OF FIGURES ----------------------------------------------------------------x
• CHAPTER 1. INTRODUCTION-------------------------------------------------1
• 1.1 Overview for Batteries ---------------------------------------------------------1
• 1.1.1 General Concepts -----------------------------------------------------------4
• 1.1.2 Classification of Batteries -------------------------------------------------5
• 1.2 Lithium Ion Batteries----------------------------------------------------------12
• 1.2.1 The History of Lithium-Ion Batteries----------------------------------18
• CHAPTER 2. RESEARCH BACKGROUND--------------------------------21
• 2.1 Solid Electrolyte Batteries----------------------------------------------------21
• 2.1.1 Positive Electrode Materials--------------------------------------------29
• 2.1.2 Negative Electrode Materials-------------------------------------------32
• 2.1.3 Ceramic Solid Electrolyte Materials-----------------------------------35
• 2.2 Lithium Polymer Electrolyte Batteries--------------------------------------48
• 2.3 Motivation----------------------------------------------------------------------51
• CHAPTER 3. GENERAL EXPERIMENTAL PROCEDURE-----------53
• 3.1 Starting Materials--------------------------------------------------------------53
• 3.2 Fabrication Process------------------------------------------------------------55
• 3.3 Characterization and Evaluation---------------------------------------------62
• CHAPTER 4. RESULTS AND DISCUSSIONS-----------------------------65
• 4.1 Ionic Conductivity of Li1.3Ti1.7Al0.3(PO4)3 Solid Electrolyte for Li ion Batteries by Sol-Gel Process ------------------------------------------------------65
• 4.1.1 Aim of Research------------------------------------------------------------65
• 4.1.2 Influence of the Processing Parameters of the Li1.3Ti1.7Al0.3(PO4)3 Solid Electrolyte---------------------------------------------------------------------67
• 4.1.3 Summary--------------------------------------------------------------------88
• 4.2 Electrochemical Properties of Ceramic-Polymer Composite Solid Electrolyte for Li-ion Batteries ----------------------------------------------------89
• 4.2.1 Aim of Research------------------------------------------------------------89
• 4.2.2 The Comparison of Electrochemical Properties between Ceramic and Ceramic-Polymer Composite Electrolyte ---------------------------------------91
• 4.2.3 Summary-------------------------------------------------------------------106
• 4.3 Effect of Li ion Contributors on the Properties of PEO Based Gum-like Electrolyte for Li Ion Batteries --------------------------------------------------107
• 4.3.1 Aim of Research----------------------------------------------------------107
• 4.3.2 Electrochemical Properties of Gum-like Composite Electrolyte According to Main Li Ion Contributor------------------------------------------109
• 4.3.3 Summary-------------------------------------------------------------------120
• CHAPTER 5. CONCLUSIONS------------------------------------------------122
• REFERENCES--------------------------------------------------------------------125
• SUMMARY IN KOREAN -----------------------------------------------------137
• ACKNOWLEDGEMENTS ----------------------------------------------------142