Consequences of Combinatorial Studies of Positive Electrodes for Li-Ion Batteries

ISBN-13: 9783319058481 / Angielski / Twarda / 2014 / 146 str.

Eric McCalla

Opis

Li-Co-Mn-Ni oxides have been of extreme interest as potential positive electrode materials for next generation Li-ion batteries. Though many promising materials have been discovered and studied extensively, much debate remains in the literature about the structures of these materials. There is no consensus as to whether the lithium-rich layered materials are single-phase or form a layered-layered composite on the few nanometer length-scales. Much of this debate came about because no phase diagrams existed to describe these systems under the synthesis conditions used to make electrode materials. Detailed in this thesis are the complete Li-Co-Mn-O and Li-Mn-Ni-O phase diagrams generated by way of the combinatorial synthesis of mg-scale samples at over five hundred compositions characterized with X-ray diffraction. Selected bulk samples were used to confirm that the findings are relevant to synthesis conditions used commercially. The results help resolve a number of points of confusion and contradiction in the literature. Amongst other important findings, the compositions and synthesis conditions giving rise to layered-layered nano-composites are presented and electrochemical results are used to show how better electrode materials can be achieved by making samples in the single phase-layered regions.

Spis treści

Chapter 1 Introduction

1.1-  Motivation: Li-Co-Mn-Ni Oxide Materials

1.2  -Layered and Spinel Structures

1.3 - The Li-Co-Mn-O Face of the Pyramid

1.4-  The Li-Mn-Ni-O Face of the Pyramid

1.4.1- Li-Mn-Ni-O Spinel Solid-Solutions

1.4.2- Li-Mn-Ni-O Layered Solid-Solutions

1.4.3- The Co-Existence Region Between the Spinel and Layered Struc­tures

1.5- Structure of this Thesis

 

 

Chapter 2 Experimental and Theoretical Considerations

2.1- Sample Preparation.

2.1.1-    Synthesis of Combinatorial Samples

2.1.2-    Synthesis of Bulk Samples

2.2-  X-Ray Diffraction.

2.2.1- High Throughput XRD of Combinatorial Samples

2.2.2- XRD of Bulk Samples

2.3- Fitting of Combinatorial XRD Patterns.

2.4- Methods to Generate the Phase Diagrams

2.5- Electrochemical Tests

2.6- Thermo-Gravimetric Analysis

2.7- Elemental Analysis

2.8- Scanning Electron Microscopy

2.9- Redox Titration

2.10- X-Ray Absorption Spectroscopy

2.11- Helium Pycnometry

2.12- Monte Carlo Simulations

 

Chapter 3 Optimization of the Synthesis of Combinatorial Samples

 

3.1- Experimental Design

3.2- TGA Results for Lithium Loss During Synthesis

3.3- XRD Results of Lithium Loss

3.3.1- Combinatorial samples

3.3.2- Combinatorial Samples During Synthesis

3.4- Conclusions Regarding Synthesis of Combinatorial Samples

 

Chapter 4 Combinatorial Studies in the Li-Co-Mn-O System

 

4.1- Experimental Design

4.2- Spinel –Layered Co-Existence Region

4.3-  LiCoO2 -Li2MnO3

4.4-  Monte Carlo Simulation

4.5-   Conclusions Regarding the Formation of Layered-Layered Composites intheLi-Co-Mn-O System

 

Chapter 5        Combinatorial Studies of the Spinel and Rocksalt Re­gions in the Li-Mn-Ni-O System

 

5.1- Experimental Design

5.3- Rocksalt Single-Phase Region

5.4- Mn2O3 –Spinel Co-Existence Region

5.5- Spinel -Ordered Rocksalt Co-Existence Region

5.6- Conclusions Regarding Spinel and Rocksalt Li-Mn-Ni Oxides

 

Chapter 6        Combinatorial Studies of Compositions Containing Lay­ered Phases in the Li-Mn-Ni-O System

6.1- Experimental Design

6.2-  Single-Phase Layered Region

6.3-  Two-Phase Layered-Spinel Region

6.4- Two-Phase Layered-Layered Region

6.5- The R,N,S and M phases

6.6-  Three-Phase Regions, Quenched

6.7-  Three-Phase Regions, Slow Cooled

6.8-  The Upper Boundary of the Layered Region

6.9-  Conclusions Regarding Combinatorial Studies of Li-Mn-Ni-O Materials

 

Chapter 7 Investigations of Bulk Li-Mn-Ni-O Samples to Confirm the Combinatorial Studies

 

7.1- Motivation

7.2- Experimental Design

7.3- Structural Results

7.4- Electrochemistry of the R, M and N Phases

7.5- Conclusions Based on Bulk Li-Mn-Ni-O Samples

 

 Chapter 8 Layered Materials with Metal Site Vacancies

 

8.1- Motivation for the Study of Samples near Li2MnO3

8.2- Experimental Design

8.3- Monte Carlo Results

8.4- Vacancy Measurements

8.5- Li[Ni1/6 1/6Mn2/3]O2

8.6- Conclusions Regarding Metal Site Vacancies in Li-Mn-Ni-O Materials

 

Chapter 9 Materials Near the Layered Boundary

 

9.1- Motivation for Studying LiNi0.5Mn0.5O2

9.2- Experimental Design

9.3- Structural Results

9.4- Monte Carlo Simulation Results

9.5- Electrochemical Measurements

9.6- Li1+x[Ni0.5Mn0.5]1−xO2 Series with 0 ≤ x ≤ 0.24

9.7- Conclusions Regarding Layered-Layered Nano-Composites

 

Chapter 10 Conclusions and Future Works

 

10.1- The Li-Co-Mn-Ni-O Pseudo-Quaternary System

10.2- Resolving Points of Confusion

10.3- Future Work

O autorze

Eric McCalla was born and raised in Quebec City.  He completed his undergraduate degree at Mount Allison University in 2000 before earning a Masters in Solid State Physics at McGill University. Following the completion of the Master’s in 2002, he become a computer science teacher in Kuujjuaraapik, an Inuit community in Northern Quebec. After two years of teaching, he decided to become a teacher and followed the Bachelor of Education program at Memorial University of Newfoundland. He then worked as a high school mathematics and science teacher in a small high school in Sept-Iles, Quebec. After biking across Canada while on sabbatical, McCalla decided to return to graduate school in 2010.  The results derived in the following three years at Dalhousie University working in the group of Jeff Dahn and are the subject of this book. McCalla is currently a Post-Doctoral Fellow at the Collège-de-France in Paris in the group of Jean-Marie Tarascon.