Preparation of Li1.03Mn1.97O4 and Li1.06Mn1.94O4 by the Polymer Precursor Method and X-ray, Neutron Diffraction and Electrochemical Studies

The compounds, Li 1.03 Mn 1.97 O 4 and Li 1.06 Mn 1.94 O 4 were prepared by the polymer precursor method followed by heat treatment at 650°C for 6 hours in air. X-ray and neutron diffraction, scanning electron microscopy, and the Brunauer-Emmett-Teller surface area and density determination techniques were used to characterise the compounds. The lattice parameters obtained using neutron diffraction data of Li 1.03 Mn 1.97 O 4 and Li 1.06 Mn 1.94 O 4 are smaller than the parent LiMn 2 O 4 at a = 8.20717(17) and 8.22899(13) Å, respectively. Cyclic voltammetry studies were carried out in the potential range of 3.5-4.4V at scan rate of 0.058 mV/sec. Li-doped LiMn 2 O 4 showed the main cathodic and anodic redox peaks at ∼3.9/4.0 and ∼4.1/4.15V, respectively. The reversible charge capacities of Li 1.03 Mn 1.97 O 4 with an applied current rate of 360 mA g −1 at the end of 2 nd and 230 th cycle are 88 and 83 (±3) mAh g −1 , respectively. At a current rate of 600 mA g −1 these charge capacities are 67 and 61 (±3) mAh g −1 , respectively. Li 1.06 Mn 1.94 O 4 shows a capacity of 64 and 62 (±3) mAh g −1 at the end of 2 nd and 100 th cycles, respectively, at a current rate of 360 mA g −1 .