Li-ion battery

An approach for constructing mathematical models of the current dependence of the capacity of electrode materials is proposed. The approach involves analyzing the probabilities of favorable and unfavorable events occurring on the elements of electrical equivalent circuits that can be used to model the electrode. Several probabilistic models that correspond to different combinations of a capacitor, a Warburg element and a constant phase element in an electrical circuit are proposed.

Features of lithiated iron phosphate behavior (PH/P1, Phostech Lithium Inc, Canada) used as positive electrode of lithium-ion battery with LiPF₆-based electrolyte were investigated. It was shown that lihiated iron phosphate potential does not depend of lithium contents in active material. It was shown that cycle life of the positive electrode strongly depends on charge/discharge current. Fast degradation of the positive electrode takes place at low current rates (0.25 and 0.5C). At the same time degradation is considerably lower at 1 and 2.5C rates.

New phases in the Li₂O-MnO₂ system were obtained, capable of introducing lithium electrochemically at potentials about 3 V and reversibly. They possess a stable capacity on the level 70-80 mA·hour/g. Due to their low cost, simplicity of synthesis, and high cycling ability, the oxides synthesized show promise as a cathodic material for lithium-ionic batteries.