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

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.