Carbon based nanomaterials have been widely used as cathode materials for Li-O₂ batteries because of their high conductivity, large surface area, and good ORR catalytic activity. However, instability of carbon under Li-O₂ operation poses problems. During recharge, carbon can decompose to form lithium carbonate at high charging potential¹, but also react chemically with the discharge product Li₂O₂ ². Metal oxides, like MnO₂ and RuO₂, have been investigated as cathode catalysts in Li-O₂ batteries³. In this study, MnO₂ nanostructure is electrodeposited on stainless steel mesh and applied as a carbon-free and binder-free cathode for non-aqueous Li-O₂ battery. To maintain good adhesion and electrical contact between deposited layer and the substrate, the mesh is pre-treated. Benefiting from enhanced electronic contact and large surface area of MnO₂, the electrochemical performance is improved. Material characterization and electrochemical impedance spectroscopy (EIS) technique are also utilized to systematically study the electrochemical processes of these carbon-free MnO₂-based electrodes.

References

[1] M.M.O.Thotiyl, S. A. Freunberger, Z. Peng, and P. G. Bruce, J. Am. Chem. Soc., 135, 494 (2013)

[2] B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshøj, J. K. Nørskov, and A. C. Luntz, J. Phys. Chem. Lett., 3, 997 (2012)

[3] Z. Ma, X. Yuan, L. Li, Z.F. Ma, D.P. Wilkinson, L. Zhang, and J. Zhang, Energy Environ. Sci., 8, 2144 (2015)

Acknowledgements

This project is financially supported by HKU Seed Fund for Basic Research (Project No.: 201605159011), and University Development Fund for Clean Energy and Environment.