Direct Growth of RuO2 Nano-Architectures on Current Collectors and Their Improved Performance in Lithium-Ion Batteries
RuO2 plays an important role in the family of metal oxides because of its interesting properties such as metallic conductivity, high chemical and thermal stability, catalytic activities, electrochemical redox properties, and field emitting behavior.4 It is one of the most successful electrode material for supercapacitors because of its wide potential window of highly reversible redox reactions, remarkably high specific capacitance, and a very long cycle life.5 In this material, conversion reaction using nanoparticles is also possible and high capacity of 1130 mAh g-1, corresponds to the storage of 5.6 moles of Li ions per mole of RuO2 and high coulombic efficiency (98%) has been observed.6But the material can withstand up to only three cycles due to a large volume expansion.
We have improved the cycle life performance of RuO2 by directly depositing the material on stainless steel current collectors via low pressure chemical vapor deposition. RuO2 nano-architectures were characterized by powder x-ray diffraction and field emission scanning electron microscope. Galvanostatic charge-discharge experiments were performed versus lithium metal in the voltage range 4 - 0.1V. As deposited RuO2 nano-architectures were cycled well over 20 cycles at high capacity beyond the theoretical limit of 806 mAh g-1(Fig. 1). The origin of the extra capacity will be discussed.
Acknowledgements: This work was supported by NSF PREM Award Number DMR-0934111 and NSF-EPSCoR Cooperative Agreement No EPS-1003897
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