Hierarchical assembly of SnO2 nanowires on MnO2 nanosheets: a novel 1/2D hybrid architecture for high-capacity, reversible lithium storage

Abstract

MnO₂, featured by an extremely high theoretical capacity (1230 mA h g⁻¹), has recently been explored as a promising anode material for lithium-ion batteries (LIBs). Moreover, MnO₂ in different nanostructures is particularly attractive because of shortened lithium diffusion pathways and increased active sites for lithium storage. However, nanostructured MnO₂ still faces unsatisfactory cyclability, especially at high rates, due to a strong inclination to aggregate as well as a low intrinsic conductivity. Here we report a novel, delicate 1/2D hybrid architecture through an elaborate morphological design, by which SnO₂ nanowires are hierarchically assembled on MnO₂ nanosheets based on van der Waals interactions. The two building blocks, hand in hand, exhibit a remarkable synergy in reversible lithium storage. On the one hand, the large, flexible and elastic MnO₂ nanosheets provide not only excellent electrochemical activities but also superior mechanical performances. On the other hand, the SnO₂ nanowires, in addition to the substantial capacity contribution, play two other vital roles: (1) acting as a spacer to isolate the MnO₂ nanosheets from restacking, thereby ensuring a large interlayer spacing for lithium diffusion; (2) serving as a conductive dopant to enable efficient, continuous one-way electron transport due to a high intrinsic conductivity. It is very encouraging to find that strikingly high reversible capacities and rate capabilities are delivered, ranking our 1/2D hybrid architecture as an advanced anode material for next-generation, high-power LIBs.