Electrospun Pd-doped mesoporous carbon nano fibres as catalysts for rechargeable Li–O2 batteries†
Abstract
Mesoporous carbon nanofibres doped with palladium nanoparticles (Pd CNFs) are synthesized by electrospinning with subsequent thermal treatment processes and used as electro-catalysts at the oxygen cathode of Li–O2 batteries. FESEM images show that the spherical Pd nanoparticles (NPs) are homogeneously dispersed on the surface of CNFs and X-ray diffraction (XRD) measurements display a fcc structure of Pd. The surface area of the nanocomposite CNFs is greatly increased with the incorporation of the metal NPs up to 600 m2 g−1 and the presence of the metal promotes graphitization of the carbon. Addition of the N-[(aminoethyl)aminopropyl]trimethoxysilane additive in the precursor solution for electrospinning allows the reduction of the Pd NPs particles size, preserving the highly mesoporous N-doped large surface area and graphitic-nitrogen groups of the carbon nanofibres. Incorporating with a Pd/CNFs catalysed cathode, the Li–O2 battery shows a very low voltage gap of 0.48 V vs. Li+/Li between the terminal discharge and charge voltages, as the recharge occurs at a potential underneath 4.0 V vs. Li+/Li for about 90 cycles at the curtailed capacity of 200 mA h g−1. The low recharge voltage can relieve parasitic reactions due to the decomposition of electrolyte and favour a longer cycle life.