Multiangular Rod-Shaped Na_0.44MnO₂ as Cathode Materials with High Rate and Long Life for Sodium-Ion Batteries

The tunnel-structured Na_0.44MnO₂ is considered as a promising cathode material for sodium-ion batteries because of its unique three-dimensional crystal structure. Multiangular rod-shaped Na_0.44MnO₂ 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 Na_0.44MnO₂ 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 Na_0.44MnO₂ provides new insight into the development of tunnel-type electrode materials and their application in rechargeable sodium-ion batteries.