Heterostructured core–shell ZnMn2O4 nanosheets@carbon nanotubes’ coaxial nanocables: a competitive anode towards high-performance Li-ion batteries

Abstract

In this study, we rationally designed a rapid, low-temperature yet general synthetic methodology for the first time, involving in situ growth of two-dimensional (2D) birnessite-type MnO2 nanosheets (NSs) upon each carbon nanotube (CNT), and we designed the subsequent phase transformation into untrathin mesoporous ZnMn2O4 NSs with a thickness of ∼2–3 nm at room temperature to efficiently fabricate heterostructured core–shell ZnMn2O4 NSs@CNT coaxial nanocables with well-dispersed and tunable ZnMn2O4 loading. The underlying insights into the low-temperature formation mechanism of the unique core–shell hybrid nanoarchitectures were tentatively proposed here. When utilized as a high-performance anode for advanced LIBs, the resultant core–shell ZnMn2O4@CNTs’ coaxial nanocables (∼84.5 wt.% loading) exhibited large specific discharge capacity (∼1033 mAh g−1), good rate capability (∼528 mAh g−1) and excellent cycling stability (average capacity degradation of only ∼5.2% per cycle) at a high current rate of 1224 mA g−1, originating from the distinct core–shell synergetic effect of fast electronic delivery and from the large electrode/electrolyte contacting surfaces/interfaces provided by three-dimensional entangling coaxial CNT-based nanonetwork topology.