импеданс

In this paper, we investigated the possibility of determining the internal resistance of the battery by pulsed method with followed Fourier transformation in transition characteristics. The changes of internal resistance of lithium sulfur cells were studied in dependence on the discharge and charge depths during continuous cycling by proposed method. It was shown that the internal resistance of lithium sulfur cell was maximal at the point corresponding to the transition between high-voltage and low-voltage plateaus both at the charge curves and at the discharge curves.

The analysis of electrochemical impedance of lithium-sulfur cells is complicated by the complexity of the processes occurring inside them. Both electrochemical processes and mass transport processes simultaneously occur on the lithium and sulfur electrodes of the cells, as well as in the bulk electrolyte. A comparative analysis of the distribution functions of relaxation times of symmetric Li||Li, S||Sand and the full lithium-sulfur cell has been conducted.

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 electrochemical characteristics of the tubular solid oxide fuel cells (SOFC) and the symmetrical anodic cells with conventional nickel-cermet and modified nickel-cobalt cermet anodes were studied using voltammetry, electrochemical impedance spectroscopy, and distribution of relaxation time analysis. The tubular SOFC with the modified anode exhibited higher power output and demonstrated lower power loss at reduced temperatures, which is attributed to higher electrical conductivity and lower activation energy of the anodic electrode reaction.

The electrochemical characteristics of the negative electrodes of the lead-acid battery with additives of carbon nanotubes and graphene were studied. It was shown that the highest values of the capacitive characteristics of the electrodes were obtained by adding carbon nanotubes to the negative active mass. The processes occurring on the negative electrode were studied by the method of impedance spectroscopy. Applying simulation, an equivalent electrical circuit was obtained, which adequately approximated the obtained frequency dependences.

The new materials obtained in the potassium polytitanate (PPT)–MnSO₄ system by modifying PPT in aqueous solutions of manganese sulfate of various concentrations, followed by thermal treatment and annealing at 1080°C, were synthesized and studied. The phase composition of the obtained materials was determined. Their electrochemical and electrophysical properties in the temperature range from 250 to 700°C were studied.

The electrochemical and electrophysical properties of the protonated and modified with silver iodide potassium titanates, which can be applied in energy storage units, have been investigated by impedance spectroscopy. It has been shown that the dielectric losses at medium and high frequencies are weakly dependent on the polarizing voltage. It has also been established that transfer in modified potassium titanate can be made through potassium and silver ions.