Литиевые электрохимические системы

Lithium-ion batteries with improved performance are increasingly in demand in various fields. Silicon-based materials are one of the most actively studied materials, because they allow increasing the discharge capacity of the anode. In this work, we continue studying the behavior of the thin-film silicon anodes inside the anode half-cell of a lithium-ion battery in the conditions of limited charge capacity to 1000 and 4000 mA·h/g.

It was studied that the quality of the electrolyte of lithium-iron-phosphate batteries has a significant effect on their service life and operational characteristics. It was shown that TS-EDM01 and DGZh018 electrolytes can be used in the production of lithium iron phosphate batteries. It was found that the use of carbon in modifying the surface of LiFePO4 and electrode manufacturing increases the stability, service life and specific characteristics of batteries.

The oxidative and hydrolytic stability of the precursors Li2S and P2S5 for the synthesis of sulfide solid electrolytes was studied using gravimetric analysis. The study was conducted in air with different water content and dry argon. It was established that the water content in air significantly affects the stability of materials. Li2S and P2S5 are unstable even in air with the water content of 5 ppm. Moreover, it was found that the oxidative-hydrolytic stability of Li2S depends on the presence of impurities.

The hydrolytic and oxidative stability of sulfide solid electrolytes Li7P3S11 and Li3PS4 at different humidity of the gas environment (air and argon) was studied. It was found that increasing the air humidity the oxidation rate of sulfide solid electrolytes also increases. It was shown that the oxidation rate of sulfide solid electrolytes depends on their composition. Thus, Li7P3S11 electrolyte has higher oxidation stability in the humid air compared to Li3PS4. Lithium sulfate is the main oxidation product of sulfide solid electrolytes.

Using the method of normalized galvanostatic curves, as well as taking into account the changes in the half-charge and half-discharge potentials of an electrode, the latter based on a sulfur composite with reduced graphene oxide, it was established that the main reason for electrode degradation during cycling was the loss of active material (due to the shuttle transfer of polysulfides and sulfur from the positive electrode to the negative lithium one).

Silicon is one of the promising anode materials for lithium-ion batteries with enhanced performance. However, the degradation of silicon during lithiation/delithiation is still the main problem that prevents it commercial use as electrodes. In this work the behavior of a silicon film of about 5–6 µm thick electrodeposited from LiCl-KCl-CsCl-K2SiF6 melt on glassy carbon was studied during its lithiation and delithiation, the film being a part of the anode half-cell of a lithium-ion battery.