cycling

The correlation between the Coulombic efficiency and the change in the residual capacity of electrodes and batteries under conditions without any parallel irreversible reactions was formulated. It was shown that this relationship allows drawing certain conclusions regarding the nature of degradation processes during cycling.

The effect of the electrode sizes, the cell design and the compression force of the electrode modules on the impedance and discharge characteristics of lithium-sulfur cells was studied. It was shown that Swagelok and pouch cells with identical electrodes have different electrochemical characteristics – charge transfer resistance, discharge capacity and cycling duration. It was found that the discharge capacity at the first cycle of Swagelok and pouch cells differs by 20% approximately. The capacity of pouch cells decreases faster during cycling.

The effect of sulfur content in positive electrodes (the surface capacity of sulfur electrodes) on the characteristics (such as the depth of sulfur electrochemical reduction, changes in capacitance and Coulomb efficiency during cycle life) of lithium-sulfur cells with electrolytes based on sulfolane was studied. It was shown that the reason for the capacitance decrease of the lithium-sulfur cells at the early stage of its cycle life is the displacement of sulfur of the porous positive electrode from the rear regions into the front ones.

In this paper, we present the results of electrochemical characterisation of a Li[Ni1/3Co1/3Mn1/3]O2 cathode material prepared by the solution combustion synthesis. Initially, [CoMnNi]Ox powder was obtained by combustion of cobalt, nickel and manganese nitrate solution with glycine or both glycine and citric acid. Li[Ni1/3Co1/3Mn1/3]O2 was then synthesised by annealing of the mixed oxide powder impregnated with lithium nitrate at 920–970°C.

Degradation of Na₂Ti₃O₇-based electrodes is studied by galvanostatic as well as electrochemical impedance spectroscopy methods. The rate of degradation was shown to decrease from cycle to cycle as the cycling progresses and also as the cycling current increases. It was concluded that the main reason of degradation is the gradual an electrolyte reduction with the formation of insoluble products (SEI).