Electrochemical performance behavior of combustion-synthesized LiNi0.5Mn0.5O2 lithium-intercalation cathodes

LiNiO2, partially substituted with manganese in the form of a LiNi0.5Mn0.5O2 compound, has been synthesized by a gelatin assisted combustion method [GAC] method. Highly crystalline LiNi0.5Mn0.5O2 powders with R3m symmetry have been obtained at an optimum temperature of 850 degrees C, as confirmed by PXRD studies. The presence of cathodic and anodic CV peaks exhibited by the LiNi0.5Mn0.5O2 cathode at 4.4 and 4.3 V revealed the existence of Ni and Mn in their 2+ and 4+ oxidation states, respectively. The synthesized LiNi0.5Mn0.5O2 cathode has been subjected to systematic electrochemical performance evaluation, via capacity tapping at different cut-off voltage limits (3.0-4.2, 3.0-4.4 and 3.0-4.6 V) and the possible extraction of deliverable capacity under different current drains (0.1C, 0.5C, 0.75C and 1C rates). The LiNi0.5Mn0.5O2 cathode exhibited a maximum discharge capacity of 174 mAh g(-1) at the 0.1C rate between 3.0 and 4.6V. However, a slightly decreased capacity of 138 mAh g(-1) has been obtained in the 3.0-4.4 V range, when discharged at the 1C rate. On the other hand, extended cycling at the 0.1C rate encountered an acceptable capacity fade in the 3.0-4.4 V range (< 10%) for up to 50 cycles. (c) 2006 Elsevier B.V. All rights reserved.