Freeze-drying preparation of MnOx/graphene nanocomposite as anode material for highly reversible lithium storage

Abstract

Manganese oxides (MnOx) as potential anode materials need support by porous carbonaceous materials to avoid its large volume change, pulverization and poor conductivity during lithiation and delithiation. However, the homogeneous distribution of MnOx particles onto graphene sheets (rGO) is still questionable, because both components have different densities and activity in solution. Freeze-drying technique has gained remarkable attention for the fabrication of porous nanocomposites. In this work, a homogeneous nanocomposite of MnOx/rGO is successfully synthesized by freeze-drying technique compared with MnOx/rGO sample synthesized by traditional drying method, and MnrGO-FD sample exhibits an improved rate performance and cyclic performance. It delivers 1446.4 mAh g−1 with Coulombic efficiency (CE) of 70.4% at the initial cycle and remains 1246.6 mAh g−1 with CE of 98.6% after 150 cycles at 0.1 A g−1. Moreover, it delivers capacity of 729.1 mAh g−1 with CE of 99.3% at 1 A g−1 for 300 cycles. Benefiting from freeze-drying, MnOx nanoparticles are distributed on porous graphene framework and graphene buffers the volume expansion of MnOx and provides conductive channels between electrolyte and active materials.