Aqueous Lithium Carboxymethyl Cellulose and Polyacrylic Acid/Acrylate Copolymer Composite Binder for the LiNi0.5Mn0.3Co0.2O2 Cathode of Lithium-Ion Batteries

Water-soluble green cathode binders are developed to increase the performance of 18650 type LiNi0.5Mn0.3Co0.2O2 (NMC532) lithium-ion batteries (LIBs). Using four basal substances to prepare the composite binders, it is indicated that the cathode with lithium carboxymethyl cellulose (CMCLi)-polyacrylic acid/acrylate copolymer (type 306F) composite binder (Marked as Binder C) avoids the corrosion of aluminum substrate, and exhibits stronger adhesive force and better electrolyte adsorption capacity compared to other cathodes with PVDF binder and single aqueous binders. In particular, the electrochemical performance of the batteries with Binder C is also improved, initial specific capacity of 161.5 mAh g-1 at 0.2 C and retention capacity of 88.9% at 1 C after 1200 cycles are obtained. The batteries with Binder C also exhibit enhanced high-temperature storage performance, there is 97.9% residual capacity when the fully charged batteries are stored in 60 °C for 14 days. The enhanced performance is mainly attributed to the chemical stability and bonding ability of polyacrylic acid/acrylate copolymer and better conduction at the liquid-solid interface caused by CMCLi. These results indicate that Binder C has promising application prospects in the NMC532 cathode, and also provide a reference for the green production of NMC-based LIBs.

Hydration of Cement in the Presence of Biocidal Modifiers Based on Metal Hydrosilicates

This article presents the results of a study of the characteristics of hydration and properties of a composite biocidal cement binder containing hydrosilicates of barium, copper or zinc. It was found that copper hydrosilicates block hydration processes, and when zinc hydrosilicates are used, the rate of hydration is determined by the content of silicic acid. The limiting concentrations of biocidal modifiers have been established: zinc hydrosilicates—no more than 4% and copper hydrosilicates—no more than 0.5%, which are advisable to use for the manufacture of a biocidal composite binder. It is shown that modifying additives slow down the setting time, the amount of tricalcium silicate in cement stones increases, and their strength for some compositions decreases. Active binding of portlandite with the formation of calcium hydrosilicates occurs when the content of zinc hydrosilicates is 2%, which leads to an increase in the strength of the materials.

ANALYSIS OF THERMAL EFFECTS WITH MULTI-FOCI STRUCTURING

The possibility of a thermal imaging technique for studying the setting of composite materials in the light of the paradigm of multifocal structure formation is analyzed. Since thermal violated observations are characterized by a high thermal sensitivity to temperature gradients up to hundredths of degrees, they make it possible to distinguish the temperature differences arising in the adjacent sections of the hardening binding. A technique for obtaining thermal images (thermograms) of a hardening composite binder is implemented. A series of thermograms of setting processes was obtained, for two of them a quantitative study was carried out, including the temperature gauge and the construction of several types of graphic mappings of the obtained patterns ‒ the normalized frequency of the distribution of the area of the binder for those temperatures and two types of densitograms ‒ radial and circular, allowing to visualize the structure of thermal foci arising in a binder. The hardening of binding materials is considered as a multistage exothermic process, in which hydration processes is accompanied by heating. The speed of heterogeneous processes associated with hydration depends, in turn, on the characteristics of the forming structure of binding materials. The observed thermal processes are considered as an indirect response, "shadow" of structure formation processes. The information consisting in this indirect response, however, is enough to make a number of conclusions on the nature of the emerging structure. The study revealed a high probability of the formation of foci near the macroscopic boundaries of the section (walls and bottom of the form), inconsistency of the structural processes, the occurrence of diverse foci of structure formation corresponding to temperature foci. The interpretation of the data obtained is the conclusion about formation of the regions of high plastic deformations near the boundaries of the contact of the foci. This regions are considered as a cluster of microscopic boundaries of the section, cracks and pores, which give rise to the structure of the destruction of the hardened material. The emergence of such areas is associated with nonynchronouspassage of structuring in different parts of the binder.

Development of Fly Ash Composite Binder and Optimization of Slurry Ratio

In view of the high cost of cement filling, the new cementitious materials are developed by using solid waste resources. Firstly, on the basis of material physicochemical analysis, the fly ash composite cementation ratio test and optimization test are carried out to determine the optimal ratio. Then, the filling body strength and pipeline transportation characteristics test are carried out to analyze they influence law. Finally, the genetic algorithm is used to optimize the slurry ratio. The results show that the strength of cemented backfill increases linearly with the increase of slurry concentration; The slump and bleeding rate of slurry decrease with the increase of slurry mass fraction, and increase with the decrease of binder sand ratio, the optimal proportion of fly ash (FA) based composite binder is w(FA): w(clinker): w (desulfurized gypsum (DG)): w (slag powder (SP)) =40:12:12:36; The optimum slurry ratio is 1:4 of binder/sand and 72% of concentration.

Effect of Humic Acid Binder on Oxidation Roasting of Vanadium–Titanium Magnetite Pellets via Straight-Grate Process

The oxidation roasting of vanadium–titanium magnetite (VTM) pellets with a new composite binder was investigated using a pilot-scale straight-grate. The evolution of the chemical and phase composition, the compressive strength, and the metallurgical properties of the fired VTM pellets were investigated. Under a preheating temperature of 950 ∘C, a preheating time of 18 min, a firing temperature of 1300 ∘C, and a firing time of 10 min, the compressive strength of the fired pellets was as high as 2344 N per pellet. The fired pellets mainly consisted of hematite, pseudobrookite, spinel and olivine. The total iron content of the fired pellets was 0.97% higher using 0.75 wt% humic acid (HA) binder instead of 1.5 wt% bentonite binder. These properties are beneficial for the production efficiency and energy efficiency of their subsequent use in blast furnaces. Moreover, both the softening interval and the softening melting interval of the HA binder pellets were narrower than those of the bentonite binder pellets, conducive to the smooth and successful smelting of the VTM pellets in a blast furnace.

Increasing the performances of low permeable cement composites

Introduction. The purpose of the article is to expand the range of compositions for special structures, which will allow them to be operated in extreme conditions. To achieve this goal, a number of tasks have been solved containing ways to improve the efficiency of composites, incl. low-permeability ones. Materials and methods. The research methodology includes a system of transdisciplinary approaches that evaluate the composite as a complex system, taking into account the provisions of geomimetics, such as the law of similarity, the law of affinity of structures, technogenic metasomatism, and micromechanics of composite media. Results. A wide range of cement concretes has been created for unique objects: low-permeability (for protective objects, reservoirs and hydraulic structures). The developed composites have the following performance characteristics (the results for the control sample are given in parentheses): water absorption by weight — 2.5 % (6.1 %), waterproof grade — W14 (W10), air permeability — 0.0253 cm3/s (0.0565 cm3/s), vapor permeability — 0.0021 mg/(m-h-Pa) (0.0030 mg/(m-h-Pa)), effective diffusion coefficient — 1.34 · 10–4 cm2/s (1.56 · 10–4 cm2/s). Conclusions. The similarity in the work of the components of different composite binders, incl. During the two-stage hydration of clinker minerals, in particular, in the first phase, the formation of low-density compounds of different phases occurs, and in the second phase, the binding of calcium hydroxide to low-basic crystalline hydrates occurs. The increase in the activity of the composite binder is due to the synergistic effect of a number of reasons: amorphous silica-containing components bind Ca(OH)2, released during the hydration of clinker minerals, in the second generation CSH(I); limestone particles clog the pores, compacting the structure; and fly ash microspheres are centers of crystallization of new growths.