Hierarchical porous MnO/graphene composite aerogel as high-performance anode material for lithium ion batteries

Abstract

MnO is a promising anode material for lithium-ion batteries due to its high theoretical capacity and low conversion potential, but it exhibits poor electrical conductivity and volume expansion and hence its practical application is hindered. In this work, we describe a high-conductive and low-expansion MnO/porous-graphene aerogel (MnO/PGA) hybrid with hierarchical pore structure, which was synthesized by a novel site-localized nanoparticle-induced etching strategy. While graphene network intrinsically guarantees fast electron transfer, it is the characteristic presence of nanosized pores on the graphene sheets that lead to high reversible capacity, favorable rate capability and cycling stability by (i) facilitating the electrolyte infiltration and shortening the diffusion distances of Li-ions, (ii) providing more defects on the graphene sheets to increase the lithium-storage active sites. As a result, the MnO/PGA hybrid exhibits a reversible electrochemical lithium storage capacity as high as 979.6 mA h g⁻¹ at 0.5 A g⁻¹ after 300 cycles and excellent rate capability of delivering 493.6 mA h g⁻¹ at a high current density of 2 A g⁻¹.