Chemical oxidation in aqueous solutions as a method for study of cathode material based on LiFePO4
In the last two decades, a huge attention has been paid to lithium-ion batteries with cathode material based on lithium iron phosphate (LiFePO4). This material is quite environmentally friendly and thermally stable in a fully discharged state. One of the main problems associated with the massive use of the cathode material, is to overcome the limitations of power, due to the slow rate of transport of lithium ions within the solid-state structures and the relatively low electronic conductivity.
A detailed study of the characteristics, mechanisms and kinetics of the processes in the cathode material should result in improvement of its performance.
The paper represents two methods for the oxidation of LiFePO4 in water medium with and without dissolving of LiFePO4. The first method was used to determine oxidation degree of the material based on the homogeneous reaction of oxidation with K2Cr2O7 in an acid solution. It has been compared with Mossbauer spectroscopy. The second method allows to determine the kinetic characteristics of deintercalation process of the cathode material and is based on a heterogeneous oxidation reaction with hydrogen peroxide in alkaline solution using a lithium ion electrode for controlling the concentration of Li+ in aqueous solution.
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