An effective integrated design for enhanced cathodes of Ni foam-supported Pt/carbon nanotubes for Li-O2 batteries.

Designing an effective microstructural cathode combined with a highly efficient catalyst is essential for improving the electrochemical performance of Li-O2 batteries (LOBs), especially for long-term cycling. We present a nickel foam-supported composite of Pt nanoparticles (NPs) coated on self-standing carbon nanotubes (CNTs) as a binder-free cathode for LOBs. The assembled LOBs can afford excellent electrochemical performance with a reversible capacity of 4050 mAh/g tested at 20 mA/g and superior cyclability for 80 cycles with a limited capacity of 1500 mAh/g achieved at a high current density of 400 mA/g. The capacity corresponds to a high energy density of ∼3000 Wh/kg. The improved performance should be attributed to the excellent catalytic activity of highly dispersed Pt NPs, facile electron transport via loose CNTs connected to the nickel foam current collector, and fast O2 diffusion through the porous Pt/CNTs networks. In addition, some new insights from impedance analysis have been proposed to explain the enhanced mechanism of LOBs.