1 Introduction ................................................. 1
1.1 Batteries: Electrochemical Energy Sources ............... 1
1.2 Lithium Batteries ....................................... 2
1.3 Present-Day Cathode Materials ........................... 4
1.4 LiFePO4: A Member of Phosphate Olivines ................. 5
2 Characteristics of LiFePO4 as a Cathode-Active Material ...... 7
2.1 Crystal Structure of LiFePO4 ............................ 8
2.2 Electrochemical Features of LiFePO4 .................... 11
2.2.1 Specific Capacity ............................... 11
2.2.2 Charge-Discharge Processes and Cell Voltage ..... 13
2.2.3 Performance on Cycling .......................... 16
2.2.4 Material Density and Energy Characteristics ..... 17
2.3 Thermal Stability and Safety ........................... 18
2.4 Electronic and Ionic Conductivities .................... 19
2.5 Models Depicting Lithium Insertion-Extraction in
LiFePO4 ................................................ 21
2.6 Existence of Path-Dependence ........................... 27
2.7 Availability, Cost and Environment-Friendliness ........ 29
2.8 Summary ................................................ 30
3 Synthesis of LiFePO4: Different Methods ..................... 31
3.1 Precursors of Li, Fe and P ............................. 31
3.2 Formation of the Crystalline Phase of LiFePO4 .......... 31
3.3 Methods of Synthesis ................................... 32
3.3.1 Solid-State (Ceramic) ........................... 32
3.3.2 Mechanical Activation ........................... 34
3.3.3 Carbothermal Reduction .......................... 34
3.3.4 Aqueous Co-Precipitation ........................ 34
3.3.5 Sol-Gel ......................................... 35
3.3.6 Hydrothermal .................................... 36
3.3.7 Emulsion-Drying ................................. 36
3.3.8 Microwave Heating ............................... 37
3.3.9 Chemical Lithiation ............................. 37
3.3.10 Spray-Pyrolysis ................................. 38
3.3.11 Pulsed Laser Deposition and Sputter
Deposition ...................................... 38
3.4 Solid-State and Solution Methods: Comparative Merits
and Shortcomings ....................................... 38
3.5 Summary ................................................ 39
4 Synthesis of LiFePO4/C ...................................... 40
4.1 Role of Carbon /Carbon-Precursor ....................... 40
4.2 Different Types of Carbon Precursors ................... 40
4.3 Synthesis of LiFePO4/C: Typical Examples ............... 41
4.3.1 Direct Addition of Carbon ....................... 41
4.3.2 Addition of Organic Compound as Carbon
Precursor ....................................... 41
4.3.3 Addition of Polymer as Carbon Precursor ......... 43
4.3.4 Carbon Coating of Olivine LiFePO4 ............... 43
4.3.5 Nano-Template Method ............................ 44
4.4 Conductive Metal Coated/Dispersed LiFePO4 .............. 45
4.5 Summary ................................................ 45
5 Influence of Synthesis Parameters on the Properties of
LiFePO4 and LiFePO4C ........................................ 46
5.1 Desirable Physical and Morphological Properties for
LiFePO4 and LiFePO4/C .................................. 46
5.2 Crystal Structure and Phase Purity ..................... 47
5.3 Morphology and Particle Size ........................... 49
5.4 Electrical Conductivity and Li+ Ion Diffusion Rate ..... 52
5.5 Optimum Carbon Coating in LiFePO4/C .................... 53
5.6 Surface Structure of Carbon ............................ 55
5.7 Electrochemical Performance ............................ 58
5.7.1 Temperature of Annealing ........................ 59
5.7.2 Carbon Coating .................................. 60
5.7.3 Novel and Efficient Processing Techniques ....... 66
5.7.4 Promising Performance of LiFePO4 ................ 67
5.8 Summary ................................................ 68
6 Metal Ion-Doped LiFePO4: Synthesis and Properties ........... 70
6.1 Doping LiFePO4 ......................................... 70
6.1.1 Doping Lithium Site ............................. 70
6.1.2 Doping Iron Site ................................ 73
6.2 Summary ................................................ 75
7 LiFePO4-Based Cathode: Influence of Different Parameters on
Properties .................................................. 77
7.1 Cathode Components ..................................... 77
7.2 Cathode Preparation Method ............................. 82
7.3. Cathode Thickness ..................................... 83
7.4 Summary ................................................ 84
8 Lithium Cells With LiFePO4 Cathode: Influence of Cell
Components and Operating Temperature ........................ 85
8.1 Cell Components ........................................ 85
8.2 Cell Performance ....................................... 85
8.3 Cell Performance at Different Temperatures and
C-Rates ................................................ 87
8.4 Summary ................................................ 91
9 Safety and Storage of Lithium Batteries with LiFePO4
Cathodes .................................................... 92
9.1 Thermal Stability ...................................... 92
9.2 Storage Stability ...................................... 94
9.3 Stability under Overcharging Conditions ................ 95
9.4 Summary ................................................ 97
10 Theoretical and Modeling Studies on LiFePO4 ................. 98
10.1 Phase Change ........................................... 98
10.2 Electronic and Ionic Conductivities .................... 99
10.3 Other Studies ......................................... 101
10.4 Summary ............................................... 102
11 Phosphate Olivines as Cathode-Active Materials ............. 103
11.1 Comparison of Theoretical Properties of LiMPO4 ........ 103
11.2 Synthesis and Electrochemical Evaluation of LiMPO4 .... 104
11.3 Studies on Li(Fe1-yMny)PO4 ............................. 107
11.4 Summary ............................................... 111
12 An overview ................................................ 112
References .................................................... 114
|
