A study about γ-MnOOH nanowires as anode materials for rechargeable Li-ion batteries

Manganite (gamma-MnOOH) nanowires have been synthesized using a hydrothermal method and their electrochemical properties as the anode materials for rechargeable Li-ion batteries have been measured. The results show that the hydroxide ions present in gamma-MnOOH do not interfere with the lithium uptake and extraction, making the manganite nanowires able to reversibly react with large amount of Li. The working mechanism of gamma-MnOOH as the anode active material for rechargeable Li-ion batteries is examined by TEM and the corresponding SAEDs, and is confirmed to be conversion reactions: during the first discharge, the gamma-MnOOH nanowires are reduced into clusters of metallic Mn embedded in an amorphous matrix of Li2O and LiOH; the subsequent cycles are reversible redox reactions between metallic Mn and Mn3O4 nanoparticles. The discharge capacity is 1660 mA h g(-1) for the first cycle and can stabilize at about 400 mA h g(-1) after 20 cycles, which implies that this material can also be a candidate for the anode electrodes for Li-ion batteries. (C) 2012 Elsevier B.V. All rights reserved.