Carbon Binder Research Articles

Решение технологических вопросов крепления постоянных магнитов на роторах электрических машин

Рассмотрены различные варианты конструкций и технологических решений, а также технология бандажирования ротора с постоянными магнитами углеродными конструкционными нитями. Описаны технологическое оборудование и оснастка для выполнения операции бандажирования. Выполнены сравнительные механические испытания углепластиковых бандажей с использованием углеродных конструкционных нитей и связующих различных производителей.

Optimization of the preparation method of a mechanically strong carbon electrode

Nowadays, a strategy for the utilization of secondary resources to obtain valuable components is actual. It will lead to the most rational use of natural resources and environmental protection. Electrochemical methods are perfectly applicable to solve this problem. Electrochemical methods allow concentrating of the target components without preliminary preparation of the raw material. Carbon materials (CM) based on plant and carbon-mineral raw materials are an excellent option as a matrix for obtaining the electrodes, due to their availability, low cost, high specific surface area, and the presence of different functional groups. The lack of theoretical substantiation of the adsorption phenomena on carbon electrodes served as an incentive for the study and development of a method for obtaining a mechanically strong electrode based on modified carbon and polyethylene. The design and mechanical strength of carbon electrodes (CE) are of great importance for the efficiency of purification and extraction of valuable components. In this article, we obtained carbon mate- rial from walnut shells by hydrothermal carbonization with further steam-gas activation (the specific surface area is 754.0 m2/g). The structural, physicochemical characteristics of the carbon material, binder, and carrier material were studied by the following methods: scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis and differential scanning calorymetry (TGA-DSC). The method of hot-pressing is applied for obtaining the carbon electrodes. Using the method of full-factor experiment and steepest ascent, the values of pressure and temperature during pressing and the ratio of carbon material: binder was optimized: P = 226 atm; T = 90.8 °C; carbon material: binder ratio = 67.5:32.5 %, respectively

Exploring Binder and Solvent for Depositing Activated Carbon Electrode on Indium–Tin-Oxide Substrate to Prepare Supercapacitors

Supercapacitor electrode slurry is prepared for mass production by mixing activated carbon powder, conductive agent, and binder, which is then deposited on a substrate using the doctor-blade method. Polyvinylidene fluoride (PVDF) and 1-methyl-2-pyrrolidone (NMP) are used as binder and solvent, respectively, to form the electrode slurry on a metal substrate. In this study, ethyl cellulose (EC) is evaluated as a binder to prepare an electrode on an indium-tin-oxide (ITO) substrate obtaining transparent supercapacitors. Terpineol and isopropyl alcohol (IPA) are compared as suitable solvents for the EC binder. When terpineol is employed as a solvent, the conductive agent is uniformly deposited around the activated carbon powder. An electrode prepared using EC and terpineol exhibits slightly lower specific capacitance and rate performance than that using conventional PVDF and NMP. However, the electrode prepared using EC and terpineol securely adheres to the electrode components, resulting in a robust electrode. In contrast, an electrode prepared using EC and IPA exhibits high charge transfer resistance at the interface of the electrode/electrolyte, leading to a low specific capacitance and rate performance. Thus, ecofriendly EC and terpineol can substitute the conventional PVDF and NMP for depositing activated carbon powder on an ITO substrate, while improving the specific capacitance of manufactured electrodes.

LiBr-coated Air Electrodes for Li-air Batteries

Li–air batteries (LAB) have a theoretical energy density as high as 3500 Wh kg−1; however, many problems remain to be addressed before their practical application. Introduction of a redox mediator (RM) is commonly applied to reduce the high overpotential of the air electrode (AE) during the charge process. We try to fix an RM on the AE by coating it with a slurry of carbon black and binder on a carbon paper substrate to enable us not only to suppress the shuttle effect but also to concentrate the RM on the surface of the AE where it works. We use LiBr as the RM in this study and compare two types of LAB cells: one with a LiBr-coated AE and the other with LiBr dissolved in the electrolyte solution. The cell with the LiBr-coated AE exhibits a better cell performance than that with the dissolved LiBr.

Electrode Microstructure and Electrolyte Conductivity Modifications to Improve Thick Sintered Electrode Rate Capability

Increasing the electrode thickness and/or reducing the inert content in a cell are routes to improve the energy density of lithium-ion batteries (Li-ion battery). Sintered electrodes have been pursued towards achieving both of those routes to increase energy density at the cell level. These electrodes are fabricated by sintering of pure active material pellets and thus do not contain any inert additives such as conductive carbon and polymer binder. The greater thickness of sintered electrodes compared to composite electrodes increases the energy density and areal capacity at the cell level. However, a limitation is that Li-ion transport in thick porous electrodes is restricted and impacts the charge/discharge capacity at high rate/current density.In this work, different approaches to mitigate transport restrictions have been investigated with sintered electrode system. First, electrolytes with different Li+ concentration and conductivity were investigated. The highest conductivity electrolyte had the highest retention of capacity at high cycling rates and was combined with pellets with directional porosity which were fabricated via ice-templating. Ice-templating alone also improved the rate capability of the electrodes in the cells, and the combined system with higher conductivity electrolyte and a directional porosity electrode demonstrated substantive retention of capacity at increasing rates. These results showed limitations of thick battery electrodes, and demonstrate possible design improvements in the context of molecular transport properties.

Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes.

The development of silicon anodes for lithium-ion batteries has been largely impeded by poor interfacial stability against liquid electrolytes. Here, we enabled the stable operation of a 99.9 weight % microsilicon anode by using the interface passivating properties of sulfide solid electrolytes. Bulk and surface characterization, and quantification of interfacial components, showed that such an approach eliminates continuous interfacial growth and irreversible lithium losses. Microsilicon full cells were assembled and found to achieve high areal current density, wide operating temperature range, and high areal loadings for the different cells. The promising performance can be attributed to both the desirable interfacial property between microsilicon and sulfide electrolytes and the distinctive chemomechanical behavior of the lithium-silicon alloy.

Enhancement of the wettability of graphite-based lithium-ion battery anodes by selective laser surface modification using low energy nanosecond pulses

The electrolyte filling process of battery cells is one of the time-critical bottlenecks in cell production. Wetting is of particular importance here, since only completely wetted electrode sections are working. In order to accelerate and facilitate this process, the authors of this study developed a method to significantly increase the wettability of graphite-based anodes by a laser surface modification using low energy nanosecond laser pulses. The anode surface microstructure was evaluated by means of white-light interferometry and scanning electron microscopy. The assessment of wettability was done by drop test and capillary rise test of the liquid electrolyte. The results show that there is a predominantly selective ablation process for laser energy inputs below 2 J/m by which the graphite active material remains unaffected and the binder material is decomposed. The observed increase in surface roughness correlates with the increasing wettability. Investigations using Raman spectroscopy showed that laser treatment leads to a damage on the crystalline structure of the graphite particle surface. However, treating an entire anode including 6 wt% binder and conductive carbon black has shown that the overall amorphous content of the anodes surface can be reduced by 32% through treating the surface with a laser energy of 1.29 J/m. Up to that point, which is the resulting parameter range for the selective process, it is possible to ablate the amorphous binder and carbon black phase coevally exposing graphite particles while keeping their crystalline structure. Exceeding that range, ablation of the whole anode composite dominates and amorphization of the graphite surface occurs. The electrode’s capacity was tested on half-cells in coin cell format. For the whole laser parameter range investigated, the anodes capacity matches the mass loss caused by laser ablation. No additional capacity loss was observed due to amorphization of the exterior graphite particle’s surface.

Low carbon binder modified by calcined quarry dust for cemented paste backfill and the associated environmental assessments

Cemented paste backfill (CPB) favors the sustainable development of mine industry. However, as the primary cementitious binders in CPB, the high cost of ordinary Portland cement (OPC) discourages CPB utilization. In the present work, low-carbon and low-cost binders activated by Na2CO3 supplemented by calcined quarry dust were used in CPB. The binder was prepared using a ‘one-part’ method. It was found that binders prepared using 8% Na2CO3 and 5% CQD show the best performance. The superior properties of the binders were attributed to the promoted binder hydration and special phase assembles of the hydration products. Cost and carbon emission analysis showed that Na2CO3 activated binder was cheaper and greener. The cost and CO2 emission of binder B8Q5 were lower than OPC by around 34.16% and 87.76%, respectively. Besides, leaching tests showed that all the toxic metals were stabilized, which posed no environmental risk.

Mechanical Properties and Microstructure of Low Carbon Binders Manufactured from Calcined Canal Sediments and Ground Granulated Blast Furnace Slag (GGBS)

This research study evaluated the effects of adding Scottish canal sediment after calcination at 750 °C in combination with GGBS on hydration, strength and microstructural properties in ternary cement mixtures in order to reduce their carbon footprint (CO2) and cost. A series of physico-chemical, hydration heat, mechanic performance, mercury porosity and microstructure tests or observations was performed in order to evaluate the fresh and hardened properties. The physical and chemical characterisation of the calcined sediments revealed good pozzolanic properties that could be valorised as a potential co-product in the cement industry. The results obtained for mortars with various percentages of calcined sediment confirmed that this represents a previously unrecognised potential source of high reactivity pozzolanic materials. The evolution of the compressive strength for the different types of mortars based on the partial substitution of cement by slag and calcined sediments showed a linear increase in compressive strength for 90 days. The best compressive strengths and porosity were observed in mortars composed of 50% cement, 40% slag and 10% calcined sediment (CSS10%) after 90 days. In conclusion, the addition of calcined canal sediments as an artificial pozzolanic material could improve strength and save significant amounts of energy or greenhouse gas emissions, while potentially contributing to Scotland’s ambitious 2045 net zero target and reducing greenhouse gas emissions by 2050 in the UK and Europe.

Carbstone Pavers: A Sustainable Solution for the Urban Environment

To reduce CO2 emissions from the building industry, one option is to replace cement in specific applications with alternative binders. The Carbstone technology is based on the reaction of calcium- and magnesium-containing minerals with CO2 to form carbonate binders. Mixes of carbon steel slag and stainless-steel slag, with tailored particle size distributions, were compacted with a vibro-press and subsequently carbonated in an autoclave to produce carbonated steel slag pavers. The carbonated materials sequester 100–150 g CO2/kg slag. Compressive and tensile splitting strength of the resulting pavers were determined, and the ratio was found to be comparable to that of concrete. The environmental performance of the Carbstone pavers, with an average tensile splitting strength of 3.6 MPa, was found to be in compliance with Belgian and Dutch leaching limit values for construction materials. In addition, leaching results for a concrete mix made with aggregates of crushed Carbstone pavers (simulating the so-called “second life” of pavers) demonstrate that the pavers can be recycled as aggregates in cement-bound products after their product lifetime.

SUGGESTIONS OF NEW TECHNOLOGIES FOR PROCESSING COAL ON THE BASIS OF USING UNIVERSAL MODULES OF INDUSTRIAL DISINTEGRATORS/ACTIVATORS

The UMID/A developed by the authors of the present paper represent the devices, which are fully compliant with the nano energetics of the Sixth Technological Paradigm and possess unique technical characteristics (extremely high density of the magnetic induction, which is close to the hundred percent of the performance factor, low consumption of materials etc.) that provides for the possibility of grinding in those modules of various materials up to nano dimensions with the purpose of using the ground materials in various sectors of industrial manufacturing, chemistry and medicine. Unique characteristics of the UMID/A determined the possibility of using such disintegrators in the principally new, developed by us technologies for obtaining inexpensive alkaline nano-cements/concretes without additional annealing of the waste of mining and metallurgy productions, inexpensive and environmentally friendly pure arbolite made of alkaline cements, boiler furnace fuel, diesel fuel, lubricating preparations made of coal inexpensive carbon nanotubes and binders of brittle and not very demanded by the construction industry inexpensive materials.

Pore Network Modelling of Galvanostatic Discharge Behaviour of Lithium-Ion Battery Cathodes

The performance of Lithium-Ion batteries (LIB’s) strongly depends on 3D microstructure and continued research is needed for the development and optimization of electrode designs to further reduce cost and improve performance and durability. In this work, a pore network modelling approach is presented to understand the structure-performance relationship of porous cathodes of LIB’s. It was demonstrated that pore network models can efficiently predict the rate-dependent capacity of an electrode using only a 3-phase tomogram as input. The developed modelling framework was used to perform structural analysis on two Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) cathodes of different thickness and calendaring pressure and revealed important insights of microstructural heterogeneities inside porous structures, including spatial distribution of concentration, potential and state of lithiation in electrolyte, active material and carbon binder domain. The computational performance of the pore network model was analyzed, and excellent performance was demonstrated, taking hours instead of weeks for a similar direct numerical simulation. The novel modelling framework reported in this study will enable the study of local heterogeneities in other types of cathode material to help screen next-generation electrode designs, augmenting and informing time-consuming cell fabrication and laboratory testing.

A Framework to Optimize Electrode Morphology

Since the invention of lithium-ion batteries, porous electrodes have been manufactured in essentially the same way: granulating active materials into powder, mixing them with some additives such as carbon black and binder, and pasting them on conductive substrate. Optimizations have been focusing on tuning parameters such as particle sizes, porosity and electrode thickness, with the assumption of a uniform electrode. Some recent work demonstrated better cell performance by engineering the shape of the electrode with features such as nano cylinders, tunnels and fractal branches. 3D printing has been used to fabricate the structure of batter electrode. On the simulation side, however, there have been few reports on freeform electrode shape optimization. Most shape optimizations assume a particular electrode pattern with a few adjustable dimensional parameters. Here we report a method to optimize porosity distribution of electrode without a prior assumption of the pattern. An NMC 333 electrode with lithium metal as the counter electrode is considered as an example. To find the optimal solid material distribution for maximum specific energy, we represented the NMC material distribution by discrete nodal design variables. To solve this high dimensional optimization problem, we used a gradient-free optimization algorithm, self-directed online learning optimization. We show that the method can produce an electrode pattern with the specific energy more than 15% higher than that of the uniform electrode. This generic distribution optimization approach provides a powerful tool for the design and optimization of porous electrodes. Figure 1

Sewage treatment sludge biochar activated blast furnace slag as a low carbon binder for soft soil stabilisation

Portland cement forms the basis of most binders used in deep dry soil mixing, significantly improving the shear strength and compressibility properties of soils. However, due to the high environmental and socio-economic impacts of cement production, there is great interest in developing alternative low-carbon binders for soil stabilisation. One of the most desirable routes involves the use of industrial by-products, such as ground granulated blast furnace slag, whose pozzolanic properties require activation by alkali agents. This paper assesses the feasibility of using sewage treatment sludge biochar as a low-carbon 100% waste-based alternative to traditional alkali agents. Two biochar:slag ratios (0.5:0.5 and 0.67:0.33) were added to an artificial soil at dosages of 7.5 and 10% by dry weight and cured for up to 56 days. The engineering performance of these stabilised soil mixtures was assessed by performing a suite of compressive strength, pH, water content, mineralogical and microstructural analyses. Results were compared with those of untreated and CEM-II stabilised alluvium, along with data published in the literature. Biochar was observed to successfully activate the pozzolanic properties of the slag, whereby the studied mixtures resulted in 28-day strengths that met European soil stabilisation standards requirements. Binder mixtures with higher biochar concentrations achieved greater strengths. The best performing mixture had a biochar-slag ratio of 0.67:0.33 and dosage of 10%, which produced strengths up to 1243 kPa. This study suggests that the biochar-slag binder has encouraging prospects for replacing Portland cements in soil stabilisation, reducing the carbon footprint of the construction sector and improving the circular economy.

Three‐Phase Reconstruction Reveals How the Microscopic Structure of the Carbon‐Binder Domain Affects Ion Transport in Lithium‐Ion Batteries

AbstractThe morphology of the electrolyte‐filled pore space in lithium‐ion batteries is determined by the solid microstructure formed by μm‐sized active material particles and the smaller‐featured carbon binder domain (CBD). Tomographic reconstructions have largely neglected the CBD, resulting in inadequately defined pore space morphologies at odds with experimental ionic tortuosity values. We present a three‐phase reconstruction of a LiCoO2 composite cathode by focused ion‐beam scanning electron microscopy tomography. Morphological analysis proves that the reconstruction, which combines an unprecedented volume (20 μm minimum edge length) with the hitherto highest resolution (13.9×13.9×20 nm3 voxel size), represents the cathode's pore space morphology. Pore‐scale diffusion simulations show consideration of the resolved CBD as indispensable to reproduce ionic tortuosity values from electrochemical impedance spectroscopy. Our results reveal the CBD as a convoluted network that dominates the pore space morphology and limits Li+ transport through tortuous and constricted diffusion pathways.

Self-healable metal-organic gel membranes as anodes with high lithium storage

Amorphous metal-organic gel (MOG) can be applied as anode for lithium ion batteries (LIBs) due to its advantages of the controllable structure and the adjustable pore size. In this work, M-MOGs (M=Ni, Zr, Fe, Al, Cr) membranes were fabricated by drop casting method and used as LIB anodes for the first time. They exhibited the excellent electrochemical performance, which were much better than metal-organic frameworks (MOFs) or MOGs without membrane formation of the same metal atom. There was no need to add carbon black, binder or organic solvent when fabricating the membrane electrode which can be attributed to the excellent electronic conductibility of membrane and the viscosity of MOGs. At the same time, the prepared MOGs have the self-healable property which can effectively restrain volume expansion during the lithium ion intercalation/extraction process. In five membrane electrodes, Ni-MOG membrane had a great specific capacity reaching to 1710.1 mA h g−1 at the current density of 100 mA g−1, and remained at 1245.5 mA h g−1 after 30 cycles with high rate performance. Furthermore, the coulombic efficiency was nearly 100% after 100 cycles at a high current density of 2 A g−1 or 5 A g−1. The conductivities of the five MOG membranes were between 10−8 and 10−7 S m−1, indicating that the membrane anodes had semiconductor property. It can be seen that amorphous MOG membrane is a promising anode material for LIBs. [Display omitted]

Production of Carbon Binders from Petroleum and Coal Derivatives

Production of Carbon Binders from Petroleum and Coal Derivatives

A Multiscale X-Ray Tomography Study of the Cycled-Induced Degradation in Magnesium-Sulfur Batteries.

Rechargeable Mg/S batteries have the potential to provide a compelling battery for a range of applications owing to their high capacity and gravimetric energy density, safety, and low-cost construction. However, the Mg/S energy storage is not widely developed and deployed due to technical challenges, which include short cycle lifespan and lack of suitable electrolyte. To study the microstructure degradation of Mg/S batteries, multiscale X-ray tomography, an inherently nondestructive method, is performed on dismantled Swagelok Mg/S cells comprising a graphene-sulfur cathode and a super-P separator. For the first time, 3Dmicrostructure visualization and quantification reveal the dissolution (volume fraction decreases from 13.5% to 0.7%, surface area reduces from 2.91 to 1.74 µm2 µm-3 ) and agglomeration of sulfur particles, and the carbon binder densification after 10 cycles. Using tomography data, the image-based simulations are then performed. The results show that the insoluble polysulfides can inevitably block the Mg2+ transportation via shuttle effect. The representative volume should exceed 8200 µm3 to represent bulk cathode. This work elucidates that the Mg/S cell performance is significantly affected by microstructural degradation, and moreover demonstrates how multiscale and multimodal characterization can play an indispensable role in developing and optimizing the Mg/S electrode design.

COMPARISON OF THERMAL DECOMPOSITION AND SEQUENTIAL DISSOLUTION—TWO SAMPLE PREPARATION METHODS FOR RADIOCARBON DATING OF LIME MORTARS

ABSTRACTDating lime mortar samples using the radiocarbon (14C) method can be difficult. This is because the contamination is similar to the primary dating material (CaCO3) and consequently difficult to remove. Mortar can also have late-in-formation pyrogenic carbonate from interactions with the environment after the initial hardening phase, such as recrystallization, fire damage or delayed hardening. When 14C dating a system of primary dating material, contamination and late-in-formation pyrogenic carbonate, one approach is multi-fraction dating with conclusiveness criteria. If a sample has sufficient contamination or late-in-formation pyrogenic carbonate, the criteria evaluate the result inconclusive. To improve inconclusive results from such samples, this study investigates sample preparation by thermal decomposition. Here samples that were inconclusively dated by the authors’ traditional method, sequential dissolution with 85% phosphoric acid, are investigated further. This study finds that CO2 thermally decomposed at low temperatures contains some late-in-formation pyrogenic carbonate. By rejecting CO2 decomposed at low temperatures, Kastelholm castle and Kimito church in Finland are conclusively and accurately dated. Furthermore, a preheating method removes some late-in-formation carbonate, but not enough for a conclusive result. Finally, thermal decomposition finds difficulty in discerning binder carbonate from limestone and marble contamination.

CNT Microtubes with Entrapped Fe3O4 Nanoparticles Remove Micropollutants through a Heterogeneous Electro‐Fenton Process at Neutral pH

AbstractCatalyst‐coated carbon electrodes require two preparation stages: electrode assembly using carbon and polymeric binders and subsequent catalyst immobilization on the porous carbons electrode. Such conventional coating methods require several steps, which is time‐, chemical‐, and energy‐consuming. Also, polymeric binders can impair the porosity and block catalytic sites of final electrodes. This study introduces a novel one‐pot synthesis method in which Fe3O4 nanoparticles are entrapped within a multi‐walled carbon nanotube network, the latter being templated with microtubular geometry. Such carbon microtubes (CMT) represent a standalone geometry, serving as a binder‐free electrode for an energy‐efficient heterogeneous electro‐Fenton (HEF) process. Fe3O4‐containing CMTs remove carbamazepine (CBZ), a frequently detected pharmaceutical micropollutant in water bodies. While almost all literature reports degradation at acidic conditions requiring the use of acid, this material system functions at pH 7 ± 0.3 with lengthy reusability. The remarkable mineralization of the total oxidized CBZ emerges from the confinement of oxidation by‐products in CMTs’ 3D framework, where unselective radicals are formed once the electro‐generated H2O2 reacts with embedded Fe3O4. Additionally, the 3D network prevents the entrapped catalysts from leaching in acidic environments because of the increased local pH during electrolysis.