Molten Salt Method of Preparation and Optimization of TiO 2 Phases Chan Tze Yang, Aloysius 1,2, M.V. Reddy 2,3 *, S. Adams 3 and B.V.R. Chowdari 2 1 SRP Student, Hwa Chong Institution, 661, Bukit Timah Road Singapore Department of Physics, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore Department of Materials Science and Engineering, National University of Singapore, Singapore *Corresponding main mentor’s address: ; 1

2

Graphite High Costs Low Charge Rates Low Thermal Stability Low Theoretical Capacity 3

4

Preparation of Compounds 5 TiOSO 4 LiNO 3 NaNO 3 KNO 3 Molten Salt Method

Preparation of Compounds TiO 2 Sample NameTemperature Used (°C) Sample 1145 Sample 2280 Sample 3380 Sample 4480 Sample 5850 reheated from Sample 1 6

Preparation of Electrodes 7 TiO2 nanoparticles Carbon Black Polyvinylidene Fluoride 70%15%

Preparation of Electrodes 8

Fabrication of Cells 9

Scanning Electron Microscopy Identification of surface morphology Sample 1 Sample 2 Sample 3 10

Scanning Electron Microscopy Identification of surface morphology Sample 4 Sample 5 11

Scanning Electron Microscopy 12 Spherical

X-Ray Powder Diffraction Determination of crystal structures Sample 2 Sample 3 Sample 4 13 Anatase

X-Ray Powder Diffraction Determination of crystal structures Sample 1 14 Amorphous

X-Ray Powder Diffraction Determination of crystal structures Sample 5 15 [5] M. V. Reddy, X. W. Valerie Teoh, T. B. Nguyen, Y. Y. Michelle Lim, and B. V. R. Chowdari Effect of 0.5 M NaNO 3 : 0.5MKNO 3 and 0.88 M LiNO 3 :0.12 M LiCl Molten Salts, and Heat Treatment on Electrochemical Properties of TiO 2. Journal of The Electrochemical Society, 159 (6) A762-A769. Anatase

Cyclic Voltammetry Investigate the redox behavior of TiO 2 in the electrolyte Voltage Range: 1.0V – 2.8V Scan Rate 0.058mV/s 16

Cyclic Voltammetry Sample 1Sample 2 Sample 3 Sample 4Sample 5 17 Anodic Scan (Ti 3+/4+ ) Cathodic Scan (Ti 4+/3+ ) Anodic Scan (Ti 3+/4+ ) Cathodic Scan (Ti 4+/3+ ) Anodic Scan (Ti 3+/4+ ) Cathodic Scan (Ti 4+/3+ ) Anodic Scan (Ti 3+/4+ ) Cathodic Scan (Ti 4+/3+ )

Galvanostatic Cycling & Capacity Fading Determine the suitability of using TiO 2 as anode material Voltage Range: 1.0V – 2.8V Current Rate: 33mA g -1 18

Galvanostatic Cycling Sample 1Sample 2 Sample 3 Sample 4Sample 5 19

Capacity Fading Studies Sample 1Sample 2 Sample 3 Sample 4Sample 5 20

Capacity Fading Studies Compound Initial Capacity (mA g -1 ) Capacity at 5 th cycle (mA g -1 ) Capacity at 50 th cycle (mA g -1 ) Percentage of capacity fading Sample Sample Sample Sample Sample

Electrochemical Impedance Spectroscopy Determine the electrode kinetics within the cell Voltage Range: 1.0V – 2.8V Frequency Range: 0.003Hz – Hz AC Amplitude: 10mV 22

Electrochemical Impedance Spectroscopy Sample 1Sample 2 Sample 3 Sample 4Sample 5 23

Electrochemical Impedance Spectroscopy Sample 1Sample 2 Sample 3 Sample 4Sample 5 24

Electrochemical Impedance Spectroscopy 25 Sample Number Average Charge Transfer Resistance Discharging (ohms)Charging (ohms) Sample 1~1500~250 Sample 2~300~40 Sample 3~250~150 Sample 4~600~90 Sample 5~550~50

Conclusions 26 Amorphous TiO2 Reheat Anatase TiO2

Conclusions 27 Better Electrochemical Properties Lower Production Temperature

Conclusions Low Costs Of Production Environmental Friendliness High Capacity Retention Highly suitable alternative anode material in Li- ion Batteries 28

Thank You 29