The tunnel-structured
Na0.44MnO2 is considered
as a promising cathode material for sodium-ion batteries because of
its unique three-dimensional crystal structure. Multiangular rod-shaped
Na0.44MnO2 have been first synthesized via a
reverse microemulsion method and investigated as high-rate and long-life
cathode materials for Na-ion batteries. The microstructure and composition
of prepared Na0.44MnO2 is highly related to
the sintering temperature. This structure with suitable size increases
the contact area between the material and the electrolyte and guarantees
fast sodium-ion diffusion. The rods prepared at 850 °C maintain
specific capacity of 72.8 mA h g–1 and capacity
retention of 99.6% after 2000 cycles at a high current density of
1000 mA g–1. The as-designed multiangular Na0.44MnO2 provides new insight into the development
of tunnel-type electrode materials and their application in rechargeable
sodium-ion batteries.