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Semelhante a Mesoporous Iron Oxide Pseudocapacitive Electrodes with Mutually High Mass Loadings and Excellent Rate Capability
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Mesoporous Iron Oxide Pseudocapacitive Electrodes with Mutually High Mass Loadings and Excellent Rate Capability
- 1. Mesoporous Iron Oxide Pseudocapacitive Electrodes with Mutually High Mass Loadings and Excellent Rate Capability Tianyu LIU Yat Li Lab Department of Chemistry and Biochemistry University of California, Santa Cruz 04/2019 ENFL #188
- 2. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 3. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 4. Supercapacitors ❑ Electrochemical energy storage devices ChargingTime LiuT. et al., J. Mater. Chem.A, 2017, 5, 17705-17733 < 1s to ~100 s ~ hours (Supercapacitors) (Batteries) vs.
- 5. Capacitance 𝐂𝐚𝐩𝐚𝐜𝐢𝐭𝐚𝐧𝐜𝐞(𝐅) = Capacity (C) Potential Window (V) A measure of the amount of charge (energy) stored ❑ A figure-of-merit of supercapacitors and their electrodes
- 6. ❑ Mechanisms Electrical Double Layer Capacitance Pseudo- capacitance Activated Carbon, CNT, Graphene etc. Conjugated polymers, metal oxides etc. ENFL #547 4/3, 2:25 pm – 2:40 pm West Hall B4,Theater 13, OCCC Capacitance
- 7. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 8. The Pros and Cons of Hematite • Pseudocapacitive • Inexpensive • Environmentally benign • Stable • Poorly conductive (e-) PROS CONS Iron oxide, hematite (α-Fe2O3)
- 9. Charge Carrier Kinetics Low mass loading e transport Ion diffusion High mass loading >5-10 mg cm-2 Commercially promising Capacitance Charge/Discharge Rate o Good rate capability o Low capacitance 0 Capacitance Charge/Discharge Rate o High capacitance o Poor rate capability 0
- 10. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 11. Ion Percolation ❑ Introducing pores Small Pores Intermediate Pores Large Pores Ion flux • High capacitance • Poor rate capability • Good rate capability • Limited capacitance Mesopore (2-200 nm) solvent
- 12. Our Design Mesoporous Iron Oxide Films
- 13. Our Design ❑ Introducing glucose Adv. Energy Mater., 2018, 8, 1801784
- 14. Our Design ❑ Formation of mesopores Adv. Energy Mater., 2018, 8, 1801784
- 15. Pore Size Controllability [Glucose] Low-magTEM Images High-magTEM Images 0.04 M 0.07 M 0.10 M 5 nm 20 nm Adv. Energy Mater., 2018, 8, 1801784 Hem-G0.04 Hem-G0.07 Hem-G0.10
- 16. Pore Size Controllability ❑ N2-physisorption results Adv. Energy Mater., 2018, 8, 1801784
- 17. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 18. Ion Diffusion Kinetics ❑ Electrochemical impedance spectroscopy Adv. Energy Mater., 2018, 8, 1801784 Slope ∝ (ion-diffusion resistivity)-1
- 19. Rate Capability Performances Adv. Energy Mater., 2018, 8, 1801784
- 20. Cycling Stability Adv. Energy Mater., 2018, 8, 1801784 Increased charge- transfer resistance
- 21. Cycling Stability Surface hydration ❑ X-ray photoelectron spectroscopy Adv. Energy Mater., 2018, 8, 1801784
- 22. Outline Background of Supercapacitors Motivation – Make Hematite Great? Synthesis and Characterizations Electrochemical Performances Summary
- 23. Conclusion o Introducing glucose in the hydrothermal system o Mesoporous iron oxide films with high mass loadings o Facilitated ion diffusion and improved rate capability 5 nm
- 24. Acknowledgements Prof. Yat Li Group, UCSC (2017) Dr. Yu Song
- 25. ENFL #547 2:25 pm – 2:40 pm,Apr. 3rd West Hall B4,Theater 13, OCCC Blending NH3 with N2 for Synthesis of N-Doped Carbon Aerogels