Porous MnNi₂O₄ Nanorods as an Efficient Bifunctional Catalyst for Rechargeable Li–O₂ battery

摘要

Spinel-type porous MnNi2O4 nanorods are prepared using a facile electrospinning and subsequentcalcination approach. A MnNi2O4 nanoparticle material is also synthesized via the sol-gel method toexplore the effect of surface area, pore diameter and pore volume on catalytic activity. The crystalphase and morphology of the samples are confirmed by X-ray diffractometry and transmission electronmicroscopy. Linear sweep voltammetry analysis shows that the MnNi2O4 nanorods electrode exhibitsbetter activities in oxygen reduction and evolution reactions than the prepared MnNi2O4 nanoparticlesor Ketjenblack electrodes. The sequenced activities of these three materials are further supported by areduction in both the discharge and recharge overpotentials during battery tests. Furthermore, batterieswith the MnNi2O4 nanorods present improved rate capability and cyclability compared with theMnNi2O4 nanoparticles and Ketjenblack. This enhanced performance is explained by the large surfacearea, mean pore diameter, and pore volume of the MnNi2O4 nanorods. These results highlight theimportance of porous MnNi2O4 nanorods as a prospective bifunctional catalyst and a potential methodof electrospinning to scale up the preparation of catalysts for rechargeable Li2 batteries.