Electrochemical System of LiTi₂(PO₄)₃ | 1 M Aqueous Li₂SO₄ | LiFePO₄ and Prototypes of the Lithium-Ion Battery Based on it

The use of aqueous electrolyte in lithium-ion energy storage systems can choose some of the problems associated with the use of electrolytes based on organic solvents, such as a risk of ignition of an abnormal violation of tightness and the sensitivity of operational parameters to production conditions.

On determination of the mechanism of the processes proceeding at syntesis of electrode material LiFePO4

The methods for the synthesis of lithium iron phosphate LiFePO4 with olivine structure have been developed. New materials based on lithium iron phosphate, including doped with metals, the «LiFePO4 + carbon» composites obtained by pyrolysis of organic compounds have been synthesized. Crystallographic characterization of the synthesized materials was carried out; their electrochemical characteristics of the extraction and intercalation of lithium have been identified. A correlation between the crystallographic and electrochemical characteristics of the materials was found. It was confirmed that an effective way to improve the electrical conductivity of LiFePO4 is to create a carbon shell of the products of pyrolysis of organic compounds on the material's particles surface. A correlation of electrical conductivity and temperature of synthesis of the material was determined. The sequence of chemical interaction between precursors for the synthesis of LiFePO4 is defined; the mechanism of solid-phase interaction is described.

A study on LiMnyFe1-yPO4 as a cathode material for lithium-ion batteries

A series of solid phases (mixed lithium-iron-manganese phosphates) of the common formula LiMnyFe1-yPO4 (0 ≤ y ≤ 1) with a carbon coating on the particle surface was synthesized by mechanochemical activation with carbothermal reduction. The synthesized mixed phosphates were examined as promising cathode materials for lithium-ion batteries. The positive effect of replacement of a rather small fraction of iron by manganese is shown, which improves the electrochemical performance at the rates C/10–10C. The highest discharging capacity (above 160 mA·h/g at the C/10 rate, about 100 mA·h/g at the 10C rate) and cycling stability (the capacity decrease rate less than 0.05 mA·h/g per cycle at the 10 C rate) were established for the weakly doped cathode material LiMn0.05Fe0.95PO4.