MnO/C-graphene composite aerogels with uniform nanoparticles anchored on GNS as high-capacity and long-life anode materials promoted by pseudocapacitance

Abstract

To effectively boost the lithium storage ability of MnO-based materials on account of the poor conductivity and volume change in the lithiation/delithiation process, the MnO/C-graphene composite aerogels are facilely fabricated by a one-step sol-gel method, in which carbon-coating MnO grains with uniform fine size are linked together and homogeneously dispersed on graphene sheets (GNS). Controlling the amount of GO addition can tune the grain size, the dispersion on GNS and the porosity of composites. When the GO addition is 0.5%, MnO/C-GNS-0.5 composites have the most homogenous nanoparticles without agglomeration or uneven size and show the largest surface area. As expected, MnO/C-GNS-0.5 displays the best lithium-storage performances with ultrahigh reversible capacity of 1310 mAh g−1 at 0.2 A g−1 after 100 cycles and long-term cycle life (98% retention after 1000 cycles at 5 A g−1), which can be ascribed to the unique architecture with dual-carbon decorated MnO and the large surface area. The coated carbon can effectively maintain structure integrity and GNS significantly improve the conductivity of electrode materials. Moreover, the large surface area and porosity enable boost pseudocapacitive lithium storage to improve rate capability and extend cycling life due to the good contact between electrode-electrolyte.