Mn2CoO4/reduced graphene oxide composite as a promising anode material for lithium-ion batteries

The use of reduced graphene oxide (rGO) as a conductive additive to enhance the discharge capacity and rate capability of Mn2CoO4 electrode material is evaluated. Mn2CoO4 and Mn2CoO4/rGO composites are prepared by a modified sol-gel method and a reflux technique, respectively. The structural and morphological features of the materials are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD shows spinel crystalline structure for Mn2CoO4. The Mn2CoO4 calcined at 800 °C exhibits a three-dimensional space network structure and has better cyclic performance than the ones obtained at 600, 700, 750 and 850 °C. Mn2CoO4 particles are anchored and dispersible on the flexible rGO for the Mn2CoO4/rGO composite. The Mn2CoO4/rGO anode shows a reversible capacity of 625 mAh/g over 50 cycles with 75.8% capacity retention of the 2nd cycle and excellent rate capability. Its rate capability and cycle stability are much better compared with those of pure Mn2CoO4calcined at 800 °C. RGO not only works as a substrate to provide space for loading scattered grains, but also serves as conductive network to facilitate the collection and transportation of electrons during the cycling, indirectly increasing the conductivity of Mn2CoO4.