Synthesis of non-stoichiometric lithium nickel cobalt oxides and their structural and electrochemical characterization

Non-stoichiometric phases of lithium nickel cobalt oxides were synthesized by a sol¯gel method using oxalic acid as a chelating agent. The structural properties have been examined using X-ray diffraction techniques. Electrochemical coin cell studies showed materials with excess lithium stoichiometry had interesting properties of improved capacity and cyclability. Of all the compositions with excess lithium stoichiometry, Li1.1Ni0.8Co0.2O2, showed better electrochemical characteristics with a first cycle discharge capacity of 182 mAh/g and a 10th cycle of 172 mAh/g than the ideal stoichiometry LiNi0.8Co0.2O2. The structural and electrochemical properties of LixNi0.8Co0.2O2 with x=1.00, 1.05, 1.10 and 1.15 are discussed in detail.