Щелочные аккумуляторы

The current situation in technology and developments in the field of polymer binders for composite electrodes of lithium electrochemical systems are discussed. A wide range of synthetic and natural polymers used for this purpose is considered. Emphasis is placed on commercially available materials, which form aqueous solutions or dispersions. The advantages of multifunctional polymer binders are demonstrated.

The paper considers the most significant properties of moulding solutions based on a mixture of polyvinylidene fluoride and polystyrene for the process of capillary-free electrospinning nonwoven materials. It has been shown that the material obtained from the mixed solution of polyvinylidene fluoride and polystyrene in the ratio of components 0.75 : 0.25 is the largest porous, the diameter of the fibers is in the widest range from 0.14 to 2.8 ?m, and branching of the fibers is observed.

The methodological issues of noise research in electrochemical systems are considered. The problem of reducing the spread of statistical estimation of the noise signal is solved. The study was conducted using specific stationary noises of a lithium battery. The analysis was performed using the two-sample dispersion method. It is shown that if the stationary conditions are met, noise measurements of electrochemical systems can provide the quality of results of high precision.

The effect of cathodic polarization on the rate of hydrogen sorption from an aqueous organic electrolyte on an Al-Sm alloy using the potentiostatic and potentiodynamic methods were studied. The obtained data allowed us to calculate the diffusion-kinetic characteristics of this process, such as the interstitial constant, diffusion constant $C_{\text{Н}}\!\!\sqrt{D}$, constant current iconst, diffusion coefficient D and adsorption of hydrogen atoms G. The number of nuclei decreases, but their mass and radius increase in the potential range from –2.0 V to –2.4 V.

The second part of the review describes the prospects of using alternative polymer binders for composite electrodes of lithium electrochemical systems. Possible options having been taken into account, the most popular commercially-available synthetic polymers with functional group (the ones forming aqueous solutions or dispersions predominantly) and water-soluble polymers of natural origin are considered. The versatility of such materials is their distinctive feature.

It was established that at the cathodic treatment of titanium in aqueous dimethyl sulfoxide solutions of sodium molybdate, containing phosphoric acid, at the potential of the cathodic incorporation of sodium (E_c  = ? 2.6 V) in the potentiostatic mode, the composition formed on the electrode surface layer depended not only on the composition of the solution, but also on the volume ratio of the aqueous electrolyte solution and the organic solvent (dimethyl sulfoxide).

A method of deriving standard electrochemical impedance spectroscopy (EIS) data such as Bode diagram, Nyquist diagram, and others from frequency dependence of the external impedance using numerical differentiation of the indicated dependence in quadratic coordinates is proposed, the method being named as the differential electrochemical impedance spectroscopy (DEIS). The method was tested experimentally on polyvinyl alcohol-based proton membranes doped with sulphated montmorillonite in granulated or dispersed states as an example.

The third part of the review is devoted to polymer binders with electronic conductivity used to make composite electrodes for lithium electrochemical systems. Polymer semiconductors (“synthetic metals”), related polymers with additionally introduced functional groups, related copolymers and mixtures of polymers, as well as carbon chain polymers and copolymers with inсorporated polyaromatic fragments are considered.

The structure and specific electrochemical characteristics of a mixed cathode material based on ground LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111) and highly porous activated carbon YEC-8B were studied. The mixed material containing 35 wt. % NMC111 and 65 wt. % YEC-8B (based on the mass of active materials), has a specific capacity ?70% higher in comparison with the cathode material based on pure coal YEC-8B.

The influence of small amounts of the Fe, Co, and Ni impurities on the spontaneous hydrolytic process of borohydride was studied within a temperature range of 60–100°C. The object under study was a simulated solution containing 9.53 M of OH^? ions and 0.14 M of BH₄^? ions, used as a fuel for borohydride fuel cells. The rate constant k of borohydride hydrolysis for a small amount of impurities at different temperature was estimated. The lowest non-accelerating concentrations of the impurities were established ( ? 10 ppm for iron? ?