Hierarchically organized CNT@TiO 2 @Mn 3 O 4 nanostructures for enhanced lithium storage performance

Here a new concept is conceived to design CNT@TiO 2 @Mn 3 O 4 nanostructures, in which CNTs, TiO 2 nanosheets and Mn 3 O 4 nanoparticles are hierarchically organized in a three-stage order. In this concept, each component plays a unique, indispensable role. In the first stage, 1D CNTs serve not only as a backbone to accommodate mechanical stress, but also as a conductive dopant to facilitate electron transport. In the second stage, 2D TiO 2 nanosheets act as a major active material to ensure high safety and a long cycle life. In the third stage, 0D Mn 3 O 4 nanoparticles function as an auxiliary active material to contribute an extraordinarily high theoretical capacity. Besides, the CNTs can minimize the restacking of the TiO 2 nanosheets, thus guaranteeing good structural integrity. TiO 2 nanosheets, being flexible and elastic in nature, are able to inhibit the aggregation of Mn 3 O 4 nanoparticles, as well as buffer the volume variation suffered during repeated lithiation/delithiation. Mn 3 O 4 nanoparticles, in turn, are capable of physically isolating the TiO 2 nanosheets to enlarge their interlayer distances for easy lithium and electron access. Thanks to the significant synergy, CNT@TiO 2 @Mn 3 O 4 nanostructures exhibit enhanced cycle and rate performances and represent a new step towards high-performance anode candidates of lithium-ion batteries.