ZnMn2O4 microtubules (ZMO-MTs) with a mesoporous
structure are fabricated by a novel yet effective biomorphic approach
employing cotton fiber as a biotemplate. The fabricated ZMO-MT has
approximately an inner diameter of 8.5 μm and wall thickness
of 1.5 μm. Further, the sample of ZMO-MT displays a large specific
surface area of 48.5 m2 g–1. When evaluated
as a negative material for Li-ion batteries, ZMO-MT demonstrates an
improved cyclic performance with discharge capacities of 750.4 and
535.2 mA h g–1 after 300 cycles, under current densities
of 200 and 500 mA g–1, respectively. Meanwhile,
ZMO-MT exhibits superior rate performances with high reversible discharge
capacities of 614.7 and 465.2 mA h g–1 under high
rates of 1000 and 2000 mA g–1, respectively. In
sodium ion batteries applications, ZMO-MT delivers excellent high
discharge capacities of 102 and 71.4 mA h g–1 after
300 cycles under 100 and 200 mA g–1, respectively.
An excellent rate capability of 58.2 mA h g–1 under
the current density of 2000 mA g–1 can also be achieved.
The promising cycling performance and rate capability could be benefited
from the unique one-dimensional mesoporous microtubular architecture
of ZMO-MT, which offers a large electrolyte/electrode accessible contact
area and short diffusion distance for both of ions and electrons,
buffering the volume variation originated from the repeated ion intercalation/deintercalation
processes.