Hydrothermal synthesis of nanostructured MnO2 under magnetic field for rechargeable lithium batteries

Nanocrystalline MnO2 was synthesized by the hydrothermal method with or without pulsed magnetic fields. It was found that the morphology of the MnO2 prepared without magnetic field has an urchin-like structure, while the MnO2 prepared with magnetic fields has a rambutan-like structure. A pronounced increase in the Brunauer–Emmett–Teller specific surface area was obtained when the intensities of the pulsed magnetic fields increased. The battery performances were improved for the samples prepared with magnetic fields. The MnO2 prepared under a magnetic field of 4 T shows a capacity of 121.8 mAh g−1, while the MnO2 prepared without magnetic field only shows 103.0 mAh g−1 after 30 cycles.