Amorphous MnO 2 thin film cathode for rechargeable lithium batteries

Abstract

MnO 2 thin films have been deposited electrochemically from a MnSO 4 solution. The deposition conditions have been optimized. The open circuit voltage versus lithium content of the Li x MnO 2 cathode shows a linear relation with a break in the slope at x=0.5. The specific energy density is 580 Wh/kg and the volume energy density 2916 Wh/ℓ. The chemical diffusion coefficient of lithium in the MnO 2 film is 4.27 to 4.85×10 −13 cm 2/s for 0≤ x≤0.2 and 1.1×10 −11 cm 2/s for x=0.9. The good reversibility of lithium insertion and extraction has been shown by voltammetry and shallow charge-discharge cycling.