1. Structural and energy storage studies of Copper Oxide Mei Shiyuan 1, M.V. Reddy 2, 3*, S. Adams 3, B.V.R.Chowdan 2 1 SRP student, Hwa Chong Institution, 661, Bukit Timah Road, Singapore 269734 2 Department of Physics, Solid State Ionics/Advanced Batteries Lab, National University of Singapore, Singapore 117542 3 Department of materials Science & Engineering; National University of Singapore, Singapore 117546 *Corresponding Author: phymvvr@nus.edu.sg;msemvvr@nus.edu.sg

2. Introduction  Power sources for portable devices  Advantages: high energy density Lightweight a long life span  Commercially used anode - graphite  Low capacity of 372 mAh per gram, compared with other materials (CuO - 650mAh per gram) Lithium Ion Battery 2

3. Introduction High theoretical capacity More eco-friendly In this project we prepared the samples at various temperatures and studied the effect of reheating them to 750 o C Copper Oxide 3 CuO has a Monoclinic structure

4. Preparation Molten salt method 4 Heat mixture Cu(SO)4·5H2O + 0.88M LiNO3:0.12M LiCl inside an Alumina Crucible at 280o C for 3 hours Cool down the sample to room temperature Reheat the sample to 750 o C for another 3 hours

5. Sample NumberMaterials used to prepare the samples Temperature heated for the first 3 hours ( o C) Temperature reheated to( o C) Sample 1CuSO 4 ·5H 2 O and 0.88M LiNO 3 :0.12M LiCl 280750 Sample 2Cu (NO 3 ) 2 ·3H 2 O and 0.88M LiNO 3 :0.12M LiCl 510750 Sample 3CuSO 4 ·5H 2 O and 0.88M LiNO 3 :0.12M LiCl 650750 Sample 4CuSO 4 ·5H 2 O and 0.88M LiNO 3 :0.12M LiCl 510750 Sample 5CuSO 4 ·5H 2 O and 0.88M LiNO 3 :0.12M LiCl 410750 Sample 6Cu (NO 3 ) 2 ·3H 2 O and 0.88M LiNO 3 :0.12M LiCl 750 Preparation conditions 5

6. Fabrication of cells  Super P Carbon – improved its conductivity  Polyvinylidene fluoride (PVDF) - binder  N-methyl pyrrolidone (NMP) – viscous slurry 6

7. Fabrication of cells Top cap Lithium Separator Anode (CuO) Electrolyte Bottom cap 7

8. Results and discussions 8

9. X-Ray Diffraction - To study the crystal structure

10. X-ray diffraction test 10 Compound name Lattice ParametersParticle size (nm)Crystal density (g/cm 3 ) CuO-280 O Ca(Å)=4.6858(5) b(Å)=3.4232(1) c(Å)=5.1291(3) beta(°)=99.47258 93.15.1291(3) CuO-510 o C- Cu(NO 3 ) 2 a(Å)= 4.6871(0) b(Å)= 3.4266(7) c(Å)= 5.1322(1) beta(°)=99.54 108.46.500 CuO-650 o Ca(Å)= 4.6848(6) b(Å)= 3.4235(0) c(Å)= 5.1291(2) beta(°)=99.46607 131.16.511 CuO-510 o C- CuSO 4 a(Å)= 4.6886(7) b(Å)= 3.4219(5) c(Å)= 5.1313(7) beta(°)=99.496 100.16.507 Reference: S. Grugeon, S. Laruelle, R. Herrera-Urbina, L. Dupont, P. Poizot, J-M. Tarascon, Journal of the Electrochemical Society, 148 (4) A285-A292 (2001)

11. Scanning electron microscopy (SEM) Sample 1-280 o CSample 5-410 o C Sample 4-510 o CSample 3-650 o C Cauliflower -like shape 1

12. Scanning electron microscopy (SEM) CuO heated directly to 750 o C : bar scale: 1 µm Spongy shape Needle shape Change in morphology Drop in capacity 12 CuO reheated to 750 o C prepared from: CuO- 750 o C MSM; bar scale: 1 µm Sample 6-750 o C

13. Cyclic Voltammetry Sample 4: CuO-510 o C -CuSO 4 MSM  Cathodic peaks Reduction: Cu 2+ to Cu metal  Anodic peaks Oxidation: Cu metal to Cu 2+  2 nd and 5 th Cycles overlap a lot  The peak density decreased for the 5 th Cycle 0.005V 3.0V 13

14. 14 1. Reddy, M. V.; Yu, C.; Fan, J. H.; Loh, K. P.; Chowdari, B. V. R., Li-Cycling Properties of Molten Salt Method Prepared Nano/Submicrometer and Micrometer-Sized CuO for Lithium Batteries. ACS Appl. Mater. Interfaces 2013, 5 (10), 4361- 4366. Cu(SO) 4 ·5H 2 O and 0.68M LiNO 3 :0.32M LiCl with a molar ratio of 1:10 Galvanostatic Cycling - To test the capacity of the cell Sample 4 – reversible capacity increased.The result is better than the cell which was heated directly to 750 o C 1 Capacities were not as high as cells heated directly to 750 o C 1 Due to their difference in morphologies

15. Galvanostatic Cycling Fig: Voltage (0.005-3.0V) vs Capacity of CuO reheated to 750 o C prepared from (a) CuO-280 o C MSM (b) CuO-510 o C-Cu(NO 3 ) 2 MSM (c) CuO-750 o C MSM 15

16. Conclusion Synthesized CuO at various temperature and reheated them to 750 o C X-Ray Diffraction (XRD) Scanning Electron Microscopy (SEM) Cyclic Voltammetry (CV) Galvanostatic Cycling studies (GC) 510 o C using CuSO 4 High and stable reversible capacity 16

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19. reserve SLIDES 28

20. Cyclic Voltammetry 1919

21. Fig: Cyclic voltammograms of CuO reheated to 750 o C prepared from (a) CuO-280 o C MSM (b) CuO-510 o C- Cu(NO 3 ) 2 MSM (c) CuO-650 o C MSM (d) CuO-510 o C -CuSO 4 MSM (e) CuO-410 o C MSM (f) CuO-750 o C MSM 20

22. Cyclic Voltammetry Fig: Cyclic voltammograms of CuO reheated to 750 o C prepared from (a) CuO-280 o C MSM (b) CuO-510 o C- Cu(NO 3 ) 2 MSM (c) CuO-650 o C MSM (d) CuO-510 o C -CuSO 4 MSM (e) CuO-410 o C MSM (f) CuO-750 o C MSM 20