Spinel LiMn₂O₄ Nanoparticles Grown in Situ on Nitrogen-Doped Reduced Graphene Oxide as an Efficient Cathode for a Li-O₂/Li-Ion Twin Battery

Seeking to design high-efficiency catalyst (LMO@N-rGO) for Li-O₂ batteries, we suggested a one-step hydrothermal strategy to grow well-crystallized spinel LiMn₂O₄ (LMO) nanoparticles homogeneously on nitrogen-doped reduced graphene oxide nanosheets (N-rGO). We found that the prepared material can yield a twin-function battery, functioning as a Li-O₂ (air) battery under the oxygen atmosphere and a Li-ion battery in the absence of oxygen. In the Li-O₂ configuration, the material displayed a lower charge plateau voltage for 0.21 V and excellent cycling performance (120 cycles at 1000 mA h g^-1 limited capacity). Furthermore, in the absence of oxygen, the material exhibited very good Li-ion battery cathode performance, achieving a capacity of up 80 mA h g^-1. On the basis of our characterization results, three reasons are suggested for the twin performance of the material: the highly uniform dispersion of LMO nanoparticles, the improved Li diffusion kinetics, and the synergic effect between the spinel LMO nanoparticles and the N-rGO.