High energy and power density Li–O2 battery cathodes based on amorphous RuO2 loaded carbon free and binderless nickel nanofoam architectures

Abstract

Herein, amorphous RuO₂ nanoflakes deposited on Ni nanofoam (NF) with diameters of ca. 30–100 nm are utilized as an innovative cathode in Li–O₂ batteries for the first time. The stability of the RuO₂/Ni NF cathode is shown to possess ca. 87.7% capacity retention after 75 cycles with minute alteration of the charge–discharge profiles. A capacity as high as 6537.8 mA h g⁻¹ based on RuO₂ weight can be reached at 0.02 mA cm⁻² with a low charge potential of 3.78 V leading to a high voltaic efficiency of 70.11%. Energy densities range from 2702.97 W h kg⁻¹ at a power density of 29.22 W kg⁻¹ to 1746.32 W h kg⁻¹ at 822.20 W kg⁻¹. The superior performance of the RuO₂/Ni NF results from the intimate contact between catalysts and current collector, and the porous nanostructure providing sufficient space for deposition of lithium oxides, and short lithium ion and oxygen diffusion pathways, as evidenced by the impedance analysis. The binder-less and carbon-free nature of the electrode prevent binder, electrode and excessive electrolyte decomposition, rendering it a prospective candidate for rechargeable Li–O₂ batteries.