Facile Controlled Synthesis of MnO₂ Nanostructures of Novel Shapes and Their Application in Batteries

Abstract

In this paper, MnO2 nanomaterials of different crystallographic types and crystal morphologies have been selectively synthesized via a facile hydrothermal route and electrochemically investigated as the cathode active materials of primary and rechargeable batteries. Beta-MnO2 nano/microstructures, including one-dimensional (1-D) nanowires, nanorods, and nanoneedles, as well as 2-D hexagramlike and dendritelike hierarchical forms, were obtained by simple hydrothermal decomposition of an Mn(NO3)2 solution under controlled reaction conditions. Alpha- and gamma-MnO2 nanowires and nanorods were also prepared on the basis of previous literature. The as-synthesized samples were characterized by instrumental analyses such as XRD, SEM, TEM, and HRTEM. Furthermore, the obtained 1-D alpha- and gamma-MnO2 nanostructures were found to exhibit favorable discharge performance in both primary alkaline Zn-MnO2 cells and rechargeable Li-MnO2 cells, showing their potential applications in high-energy batteries.

Facile synthesis and magnetic properties of manganese dioxide nanowires

“…The first discharge capacity reaches 223.5 mA h g À1 . The value is slightly higher than that observed in the data of commercial -MnO 2 powders and reported 1-D nanostructures, and much higher than that of bulk materials [37,38]. The value of discharge capacity is relatively decreased rapidly with cycling from 1 to 10 times, and is steadily decreased in the following cycles, down to an acceptable capacity of 122.3 mA h g À1 after 25 cycles.…”

“…The as-synthesised MnO 2 nanowires were employed as cathode active materials for rechargeable lithium-ion cells. The detailed measurement process is in accordance with the literature [37].…”

Hierarchical urchin-shaped α-MnO2 on graphene-coated carbon microfibers: a binder-free electrode for rechargeable aqueous Na–air battery

“…Furthermore, the nanowire morphology minimizes the distance over, which the Na + ions have to diffuse during the redox processes and decreases the electrode polarization. [39][40][41][42] At the same time, highly crystalline MnO 2 nanowires are also sufficiently exposed for the O 2 diffusion and electron transport, greatly benefiting the ORR. Thus, owing to the urchin shape of the MnO 2 , the MGC electrode exhibits an excellent rechargeable performance.…”

Effect of hemochromatosis on manganese neurotoxicity

“…Large amounts of Mn are used in agricultural fungicides, welding rods coating, and in steelmaking [121,150]. Also, Mn is used in novel applications of nanoparticles (MnO2 and Mn3O4), including batteries, sensors and waste water treatment [151][152][153]. Workers are exposed through inhalation to both engendered Mn nanoparticles and metal fumes [154,155].…”