卷 23, 编号 1 (2023)
Articles
Digital oscillography of proton-conductive polymer membranes
摘要
Polyvinyl alcohol-based cast membranes have promising application in creating commonly available fuel cells and fuel synthesizers, as well as inexpensive water sources and microelectromechanical systems. In order to control the properties of such membranes a deep understanding of the charge transfer mechanisms and their relationship with the structure formed at a certain composition and manufacturing technology is required. A method for studying the structure of the proton-conductive polymer membranes using digital oscillography of ion currents excited by the low-frequency rectangular pulses with the amplitudes below the threshold voltage of the ionic conductivity in a dehydrated membrane, and for the analysis of the resulting ion current pulses (spikes) in the frames of the model of a proton pump acting in each layer of the membrane is proposed in this paper. Fast Fourier transform of these oscillograms reveals from 2 to 4 branches or spike sequences corresponding to the phases with different ionic conductivity and makes it possible to determine the thicknesses of both high-conductivity phase layers (7–30 µm) and low-conductivity phase interlayers (1–7 µm) formed in the process of polymerization. The reason of spike merging into bursts is described in terms of successively induced increase in the excited proton density over a threshold value in highly conductive layers. The resonance observed in dry proton membranes at the frequencies of about 2.2 to 3.0 kHz is interpreted as the burst merge point with the further increase in impedance due to proton lagging and respective decrease in the effective thickness of active layers. The effective charge carrier concentrations (as small as 1012 to 1013 cm−3) and the velocity (from 5 to 18 cm/s for the highly conductive phases which turned out to be much higher than those observed in solutions) are estimated. The asymmetry of the cast membranes, which becomes apparent at low frequencies and causes the generation of a direct ion current in response to excitation by a purely alternating current, is studied. It is found that the apparent conductivity determining contribution to the total ohmic resistance is made by a thin interlayer with a very low ion velocity, presumably surface layer, rather than the main layers. The conclusion on the optimization of the production technology and the composition of the proton membranes for various applications is made.
Electrochemical Energetics. 2023;23(1):3-25
3-25
Impediance spectroscopy of modified potassium titanates. II
摘要
The electrochemical and electrophysical properties of basic and protonated potassium titanates in contact with the graphite electrodes were studied using the method of impedance spectroscopy. The characteristics of potassium titanates are given depending on the methods of modification and on the methods of their processing. The activation energies for some compositions were determined.
Electrochemical Energetics. 2023;23(1):26-32
26-32
Electrochemical reduction of multilayer graphene oxide in alkaline electrolyte
摘要
The results of the study of the electrochemical reduction of multilayer graphene oxide in the potentiostatic mode are presented and the possibility of using alkaline electrolyte (KOH) with the concentration below 0.1 M is shown. The identification of the electrochemically reduced graphene oxide was carried out using the XRD, FTIR and Raman-spectroscopy methods. Applying the method of Raman spectroscopy the increase in the intensity of the G and 2D bands, indicating the formation of few-layer forms of reduced graphene oxide was found. The surface morphology of the electrochemically reduced graphene oxide was studied by means of the SEM method.
Electrochemical Energetics. 2023;23(1):33-40
33-40
C/SiC-based anodes for lithium-ion current source
摘要
Compositions of ultrafine Si and C particles are promising anode materials for lithium-ion power sources with improved energy characteristics. In the work, samples of lithium-ion power sources with an anode made of ultrafine SiC fibers, as well as mixtures of SiC fibers with graphite (C/SiC) and electrolytically deposited submicron silicon fibers (C/Si/SiC) were fabricated and studied for energy characteristics. The working ability of the mixtures obtained during lithiation/delithiation was shown, and the main energy characteristics of the investigated anode half-cells were determined. After 100 cycles, the SiC anode reached a discharge capacity of 180 and 138 mA⋅h/g at a charge current of C/20 and C, respectively. Anodes made of mixtures (wt%) 29.5C-70.5SiC and 50Si-14.5C-35.5SiC show discharge capacities of 328 and 400 mA⋅h/g at a charge current of C/2. The Coulomb efficiency of all samples was above 99%.
Electrochemical Energetics. 2023;23(1):41-50
41-50
International Specialized Fair “INDEPENDABLE POWER SOURCES – 2023”
摘要
Международная специализированная выставка «Автономные источники тока – 2023» Дата проведения: 10–12 апреля 2023 Место проведения: г. Москва, ул. Новый Арбат, д. 36, фойе БКЗ здания Правительства Москвы. Время работы выставки: 10–11 апреля 2023 10.00–17.00 12 апреля 2023 10.00–12.00 Организатор: Национальная ассоциация производителей источников тока «РУСБАТ»
Electrochemical Energetics. 2023;23(1):51-52
51-52