Alkyl Carbon Research Articles

Methods–Temperature-Dependent Gassing Analysis by On-Line Electrochemical Mass Spectrometry of Lithium-Ion Battery Cells with Commercial Electrolytes

The evolution of gases is often associated with the decomposition of the electrolyte or active materials. Thus, its detection can be powerful for understanding degradation mechanisms in Li-ion batteries (LIBs). Here, we present an evaluation method for gas detection and quantification by on-line electrochemical mass spectrometry (OEMS) when using volatile electrolytes (e.g., electrolytes with linear alkyl carbonates) and a new OEMS cell design for improved leak tightness. With a significant fraction of the gases in the cell head-space being electrolyte vapor, we observe a pressure/time-dependency of the electrolyte background in the mass spectrometer, for which we here developed a correction method. We apply this method for the temperature-dependent gas analysis of a graphite/NCM831205 full-cell with an LP57 (1 M LiPF6 in EC:EMC 3:7 wt:wt) electrolyte. We conclude that the activation energy of the gas evolution associated with the formation of the solid-electrolyte interphase (SEI) is ∼15–20 kJ mol−1. Furthermore, we identify a significant temperature dependence of the lithium alkoxide triggered trans-esterification of EMC with an activation energy of ∼70 kJ mol−1. Lastly, the temperature-dependent analysis reveals the relation between the evolution of hydrogen related to water and HF impurities during the initial SEI formation and in situ generated protons.

Synthesis of Two-Dimensional Zeolite Nanosheets Applied to the Catalytic Cracking of a Waste Cooking Oil Model Compound to Produce Light Olefins.

Hierarchical zeolites can provide multidimensional spatial networks and, therefore, have significant potential as catalysts for the cracking of biomass to generate light olefins. The present work synthesized the diquaternary ammonium-type surfactant [C18H37-N+(CH3)2-(CH2)6-N+(CH3)2-C6H13]Br2, incorporating hydrophobic 18-carbon alkyl groups for usage as a structure-directing agent. This compound was subsequently used to prepare nanosheets of a hierarchical ZSM-5 two-dimensional zeolite (HNZSM-5) through a one-pot hydrothermal method. The crystal phase, morphology, and hierarchical structure of the HNZSM-5 were analyzed using various techniques, including X-ray diffraction, electron microscopy, and N2 adsorption/desorption. When applied to the catalytic cracking of a waste cooking oil model compound, the HNZSM-5 exhibited superior activity and stability compared with a conventional ZSM-5. This performance was attributed to the more accessible acid sites and unique lamellar structure of the former material. The HNZSM-5 also outlasted the conventional zeolite, showing deactivation after 45 h of reaction compared with 20 h, indicating exceptional stability and excellent resistance to coking.

Impact of Salts and Linear Carbonates on the Performance of Layered Oxide/Hard Carbon Sodium-Ion Pouch Cells with Alkyl Carbonate Electrolytes

This study examines the influence of electrolyte salts and solvents on the performance of O3 layered oxide NaMn0.39Fe0.31Ni0.22Zn0.08O2/hard carbon sodium-ion pouch cells with polyethylene terephthalate (PET) jellyroll tape. A significant enhancement in cell performance between 2.0 and 3.8 V was observed across various temperatures (20, 40, and 55 °C) by substituting NaPF6 with NaFSI, including reduced impedance growth, minimized gas generation, and supressed jellyroll tape decomposition. Ultra-high precision coulometry revealed that the use of NaPF6 resulted in increased unwanted parasitic reactions associated with tape decomposition, e.g., capacity fade and charge endpoint capacity slippage. Teardown of sodium-ion pouch cells after cycling in DMC-based electrolytes revealed a severe decomposition of the PET tape with NaPF6 but not with NaFSI. Gas chromatography shows significantly more electrolyte decomposition products with NaPF6 as opposed to NaFSI. DEC-based electrolyte showed less capacity fade, less electrolyte decomposition products, and less tape decomposition after cycling than DMC-based electrolyte. The electrolyte additive DTD can prevent parasitic reactions in DMC- and NaPF6-based electrolyte. Overall, the choice of salts and linear carbonates in alkyl carbonate electrolytes plays a crucial role in determining the overall cycling performance of the layered oxide/hard carbon sodium-ion cells with PET jellyroll tape.

The Impact of Chemical Modifications on The Ionic Conductivity of Ionic Liquid Encapsulated in Carbon Nanotubes, Potential Application in Aluminum Ion Battery

The transport and thermodynamic properties of 1-ethyl-3methyl imidazolium hexafluorophosphate ([EMIM][PF6]) ionic liquid encapsulated in carbon nanotubes or graphite represent a significant challenge in the development of Aluminum-ion batteries. To achieve high energy density in Aluminum-ion batteries, it is explored the use of ionic liquid solvents as electrolytes to enhance the ionic conductivity of the ionic liquid when encapsulated in carbon nanotubes as electrodes. The doping effects of sulfur and boron atoms in single-walled carbon nanotubes (SWCNTs) have been investigated to determine their impact on the ionic transfer number of the ionic liquid encapsulated in SWCNTs. The Green-Kubo formalism has been employed to calculate the ionic transfer number and electrical conductivity of the ionic liquid when encapsulated in SWCNTs doped with sulfur and boron atoms. The results obtained using the Green-Kubo formalism indicate that sulfur doping in SWCNTs, particularly in those with a larger radius, serves as a selective porous electrode material, significantly enhancing the electrical conductivity of the confined ionic liquid. Furthermore, the radial distribution function between the carbon alkyl groups in the ionic liquid and the carbon wall of the carbon nanotube, which is doped with sulfur and boron atoms, demonstrates that the doping effect does not alter the radial distribution function. The Green-Kubo result obtained for the electrical conductivity of the ([EMIM][PF6]) ionic liquid demonstrates excellent agreement with the experimental data.

Analysis of natural organic matter chemistry in bentonite clay under compaction using different dry densities and duration

The Nuclear Waste Management Organization of Canada has adopted an adaptive phased management plan for the long-term storage of used nuclear fuel in a Deep Geological Repository (DGR). The DGR barrier system employs copper-coated used fuel containers (UFCs) surrounded by buffer material which is composed of highly compacted bentonite clay. The natural organic matter (NOM) composition of the compacted bentonite is of practical importance for the safety assessment as it regulates the biogeochemical processes at the interface between the UFCs and the buffer layer. However, insufficient investigations on NOM constituents limits the understanding of biogeochemical dynamics in bentonites compacted under different dry densities. This study analyzed the carbon content and NOM composition using targeted compound analysis and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with bentonites compacted at 1.1, 1.4 or 1.6 g/cm3 dry density for 1, 3, 6, 12 or 18 months. Organic carbon contents were similar across bentonites with different compaction densities at various durations as compared to the reference clay (powdered bentonite sample before compaction). The overall NOM composition measured by solid-state 13C NMR suggested a predominance of alkyl and aromatic carbon in bentonite samples. No marked variations were observed for the NOM components (i.e., alkyl, O-alkyl and aromatic carbon) between the compacted bentonites and the reference clay. Targeted compound analysis revealed that the extractable lipid concentrations in the compacted clays did not significantly vary from the reference bentonite with only some compounds exhibiting nano-gram level differences. Bentonites with relatively lower dry densities (1.1 and 1.4 g/cm3) demonstrated slightly higher extractable compound concentrations, but these differences were not statistically significant. In contrast, the compound concentrations of bentonites compacted to 1.6 g/cm3 were similar or slightly lower compared with the reference bentonite, likely associated with limited microbial growth under high dry compaction density. Taken together, these results suggested that NOM composition and quantity did not significantly alter in bentonites under various pressures nor with longer experimental durations. These findings highlight that compacted bentonite exhibited geochemical stability under the simulated repository environments, which provides critical insight for design and performance of engineered barrier system in a DGR concept.

Fundamental properties and intermolecular interaction of triethylene glycol + ethylenediamine aqueous solution for CO2 capture

Solvent absorption as a significant method for carbon dioxide capture, exploring the mechanism of CO2 capture and regeneration solvents is essential for industrial applications. In this work, water (H2O) + (ethylenediamine (EDA) + triethylene glycol (TEG)) system with the constant mole ratio (TEG: EDA = 1: 1) was chosen as the liquid absorbent. In order to gain a deeper comprehension of solution properties of H2O + (EDA + TEG) system, the density (ρ) and viscosity (η) of fundamental properties were measured at P = 1005 hPa and T = (298.15 K to 318.15 K) with the temperature step of 5 K. The excess properties, including excess molar volume (VmE), viscosity deviation (Δη), and excess Gibbs energy of activation of viscous flow (ΔG*E) of H2O + (EDA + TEG) system were calculated from the experimental ρ and η values, and fitted well with the Redlich-Kister polynomial equation. The above results combined with the spectra proved the existence of intermolecular interaction in H2O + (EDA + TEG) system, which favorably fixed CO2. Subsequently, the aqueous solution with mass fraction of 15 wt% EDA and molar ratio EDA: TEG = 1: 1 was used for absorbing CO2 (room temperature) and desorbing (378.15 K) for 5-time cycles, and the cycling absorption performance decreased. So as to explore the reason of degradation, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance carbon spectroscopy (13C NMR) were used to analyze the circulating absorption mechanism of CO2 in H2O + (EDA + TEG) system, which revealed that alkyl carbonates and partially indecomposable substance 2-imidazolidinones generated in the cyclic process, and provided some implications for the industrial application.

A Guide for Mono-Selective N-Methylation, N-Ethylation, and N-n-Propylation of Primary Amines, Amides, and Sulfonamides and Their Applicability in Late-Stage Modification.

This review provides a comprehensive overview of mono-alkylation methodologies targeting crucial nitrogen moieties - amines, amides, and sulfonamides - found in organic building blocks and pharmaceuticals. Emphasizing the intersection of chemical precision with drug discovery, the central challenge addressed is achieving one-pot mono-selective short-chain N-alkylations (methylations, ethylations, and n-propylations), preventing undesired overalkylation. Additionally, sustainable, safe, and benign alternatives to traditional alkylating agents, including alcohols, carbon dioxide, carboxylic acids, nitriles, alkyl phosphates, quaternary ammonium salts, and alkyl carbonates, are explored. This review, categorized by the nature of the alkylating agent, aids researchers in selecting suitable methods for mono-selective N-alkylation.

Facile and Scalable Fabrication of Regenerated Cellulose Microspheres with High Strength and Porosity as a Potential Matrix for Hemoperfusion

For acquiring an ideal sorbent for hemoperfusion, three crucial problems should be addressed: 1. The gap between the stacked sorbents should be larger than the blood cells, around 600 μm, for a continuous pass-through of blood in a hemoperfusion device. 2. The hemoperfusion device should maintain at least a 190 ml/min flow rate. 3. Specific binding on the sorbents is required to absorb the harmful agent in blood. In this research we developed a low-surfactant emulsification technique to prepare physically crosslinked cellulose microspheres (CMs). The particle size of the CMs could be tuned from 150 μm to 1000 μm. Three dehydration methods also regulated the mechanical properties of the CMs. The perfusion column stacked by physically crosslinked CMs, after being treated by an ethanol bath, could withstand pressure induced by a flow rate of 190 ml/min. The adsorption processes of hydrophobic alkyl carbon chain (C18) modified CMs for bilirubin conformed to the Langmuir isothermal adsorption model, which indicated that the bilirubin adsorption by C18 grafted CMs mainly relied on the interaction between C18 and bilirubin. In summary, a facile, scalable and low-surfactant fabrication strategy was developed to synthesize regenerated cellulose microspheres with high strength and porosity as a promising absorbent for hemoperfusion.

Control of Polar/Antipolar Layered Organic Semiconductors by the Odd-Even Effect of Alkyl Chain.

Some rodlike organic molecules exhibit exceptionally high layered crystallinity when composed of a link between π-conjugated backbone (head) and alkyl chain (tail). These molecules are aligned side-by-side unidirectionally to form self-organized polar monomolecular layers, providing promising 2D materials and devices. However, their interlayer stacking arrangements have never been tunable, preventing the unidirectional arrangements of molecules in whole crystals. Here, it is demonstrated that polar/antipolar interlayer stacking can be systematically controlled by the alkyl carbon number n, when the molecules are designed to involve effectively weakened head-to-head affinity. They exhibit remarkable odd-even effect in the interlayer stacking: alternating head-to-head and tail-to-tail (antipolar) arrangement in odd-n crystals, and uniform head-to-tail (polar) arrangement in even-n crystals. The films show excellent field-effect transistor characteristics presenting unique polar/antipolar dependence and considerably improved subthreshold swing in the polar films. Additionally, the polar films present enhanced second-order nonlinear optical response along normal to the film plane. These findings are key for creating polarity-controlled optoelectronic materials and devices.

Microscopic mechanism of carbon oxides formation during long-flame coal oxidation at molecular scale

Precursors of carbon oxides in coals are considered to be related to aldehyde group(–CHO) and carboxyl group (–COOH), but the way of decomposition of precursors to produce carbon oxides is not clear. Through theoretical analysis, experimental research and quantum chemical calculation at molecular scale, this paper explores the decomposition mode and products of carbon oxide precursors during coal spontaneous combustion (CSC). A programmed heating device was used to investigate the change rule of gas product concentration during the constant temperature oxidation of coals, and the microstructure of the coals was characterized by low-temperature nitrogen adsorption experiments (BET), X-ray Diffraction (XRD) and X-ray photoelectron spectrometer (XPS). The results of the study show that during coal oxidation, the inhomogeneous energy exchange between the coals and the external heat source results in the change of gas product concentration with time following two rules. BET experiments reveal that oxidation leads to the evolution of fine mesopores to macropores and an increase in the number of pores with diameters larger than 20 nm in the coals, which facilitates the transport of oxygen molecules through the pore structure. Within 200 °C, the microcrystalline structure of coals is basically unchanged, and the active structure C–C/C–H on the side chain is converted to –CHO and –COOH and then decomposed to produce carbon oxides. Quantum chemical calculation shows that the reaction energy barrier of carbonyl group and carboxyl group decomposed step by step to form carbon oxides is much smaller than that of direct decomposition, and carbon oxides and alkyl radicals can be produced even at room temperature by step decomposition. The research results provide theoretical guidance for the formation mechanism of carbon oxides during low temperature oxidation of coals.

Disparity among cyclic alkyl carbonates associated with the cathode–electrolyte interphase at high voltage

The schematic of CEI evolution.

Activation of C(SP3)–H Bonds Promoted Oxidation of Sulfides by O2 Under Catalyst-Free Conditions

Oxidation of organic sulfides is a significant reaction due to its application in many fields. Herein, we have developed a novel catalyst-free oxidation of organic sulfides by O2 under relatively mild conditions. The choice of the procedure was based on the well-acknowledged reactivity of the active C(sp3)-H bond of organic compounds to form the corresponding alkyl carbon free radicals (Rand#183;) in the presence of O2. The results showed that hydrocarbons such as tetrahydronaphthalene (THN) and cumene possessing the active C(sp3)-H bonds due to their lower bond dissociation energy (BDE), as a solvent, markedly promoted this catalyst-free sulfoxidation. It has been proved that reactive oxygen species (ROS) in this reaction are alkyl-peroxide radicals that are produced from Rand#183;, which is derived from the homolytic cleavage of the active C(sp3)-H bond with the help of heating and dioxygen, and further its activation of molecular oxygen. On this basis, combined with the DFT calculation of the activation energy of two reaction pathways, a possible reaction mechanism is proposed. The work provided a green synthesis approach of sulfoxide and sulfone compounds, and a scientific basis for a green process of ultra-deep desulfurization of fuel oils.

Nanoparticle-enabled integration of air capture and conversion of CO2.

Integrating air capture and conversion of CO2 is key to realizing energy sustainability. However, current integration approaches require high temperature and pressure, making them energy intensive. Here, we demonstrate a nanoparticle (NP) catalysis approach for the hydrogenation of alkyl carbonate, an intermediate obtained from the CO2 capture process, to formate, achieving one-pot air capture and conversion of CO2 under ambient conditions. The capture is realized in an ethylene glycol (EG) solution of KOH (EG-KOH) at room temperature, where CO2 is selectively converted into HO-CH2CH2-O-COOK (∼100% conversion). This carbonate is then hydrogenated using ammonia borane (under ambient pressure and at 50 °C) to formate (HCOOK) (>90% yield) in the presence of a stable Pd NP catalyst with EG being regenerated. Atomistic simulations suggest that the CO2 absorption process in the EG-KOH solution is energetically stable, and the catalyst surface provides the reaction site to break the C-O bond in the -O-COOK structure, enabling the hydrogenation of the alkyl carbonate to formate and the regeneration of EG. Our study provides a promising NP-catalysis approach for air capture and conversion of CO2 into value-added chemicals/fuels under ambient conditions.

Organic Modification of Silica-Based Ionogels Improves the Electrolyte/Electrode Contact and Influences Their Functional Properties

The energy transition necessitates sustainable energy storage to address the mismatch between the production and consumption of renewable electricity. Sodium-ion batteries (SIBs) are a promising candidate for stationary energy storage as an alternative for lithium-ion batteries (LIBs). In spite of their lower energy density, SIBs have advantages over LIBs.1 Sodium is considerably more abundant than lithium (2.83% versus 0.01%) and, evenly distributed across the Earth, implying that SIBs may be less expensive and more sustainable than LIBs.1,2 Conventional LIBs contain flammable organic liquid electrolytes (e.g. alkyl carbonates) with limited thermal stability. Thermal runaway can therefore lead to cell ignition, causing a significant safety hazard. Non-flammable electrolytes can be based on ionic liquids, which are molten salts with flame retarding properties and negligible vapor pressures. However, the possibility of leakage and related environmental hazards remains a concern.3 This risk can be mitigated by the use of solid electrolytes. Apart from circumventing safety issues, solid electrolytes may allow a significant increase in energy density. After all, they take up less dead volume than liquid electrolytes and can allow the use of alkali metals as negative electrodes.An attractive type of solid electrolyte is the class of silica-based ionogels, owing to their high ionic conductivity, thermal stability, and broad electrochemical window.4 They comprise an ionic liquid electrolyte (ILE, a salt dissolved in ionic liquid) confined in the pores of a solid silica matrix. The silica matrix is electrochemically inactive but influences the functional properties of the resulting solid material. Ionogels based on solely silica (SiO2) as matrix tend to crack easily when subjected to pressure as the rigid Si-O-Si bonds result in high Young’s modulus materials. Furthermore, materials with high Young’s moduli cannot adapt easily to electrode surfaces, resulting in higher charge-transfer resistances (Rct) between the solid electrolyte and electrode. One way to reduce the stiffness of silica-based ionogels is to modify the silica matrix with e.g. organic groups. Ormosils® are a class of materials completely consisting of organically modified silica and show mechanical properties from glassy to rubbery depending on the amount of organic modification.5 Here, the concepts of ionogels and Ormosils® are combined to produce sodium-ion conducting organically modified ionogels. Two different phenyl-bearing silanes (phenyltrimethoxysilane, PhTMS, or diphenyldimethoxysilane, DPhDMS) are for the first time used as organic modifiers in silica-based ionogels. A non-aqueous sol-gel route with formic acid (FA) is used to synthesize the monoliths. Incorporating phenyl groups allow to reduce the Young’s modulus from 29 MPa down to 6 MPa. The charge-transfer resistances (Rct) of Na|ionogel|Na2Ti3O7 half cells, determined with electrochemical impedance spectroscopy (EIS), followed the trend of the ionogels’ Young’s modulus. Through NMR spectroscopy, pi-stacking was observed between the matrix phenyl moieties and IL imidazolium cations. Furthermore, the organic modification diminished the formation of hydrogen bonds between IL anions and matrix silanol groups. This shows that the organic modification of the matrix can have a pronounced effect on the coordination of the ILE components, which ultimately determine the solid electrolyte’s functional properties. In summary, incorporating phenyl groups in the silica matrix of ionogels improves the mechanical properties and charge transfer resistances, but impairs ionic conductivity. Acknowledgments: This research is made possible by the Research Foundation Flanders (FWO, project G053519N and 1S08921N) and the Special Research Fund (BOF) of Hasselt University (BOF20INCENT19). This work is further supported by Hasselt University and FWO Vlaanderen via the Hercules project AUHL/15/2 - GOH3816N.

Influence of Cyclic Alkyl Carbonate Ring-Opening Processes on Electrode/Electrolyte Interphase Formation in Li-Ion Batteries

Cyclic alkyl carbonates, such as ethylene and vinylene carbonate (EC and VC), form solid electrolyte interphases (SEI) suppressing continuous solvent reduction at the graphite anode. There is a consensus that the choice of carbonate clearly affects SEI performance. VC has been observed to polymerize, forming poly(VC), but also to release major amounts of CO2,1,2 which are two seemingly contradictory processes. In this work, we present a detailed study of reaction pathways of EC and VC in typical Li-ion battery electrolytes. The rate of the decomposition reactions of these carbonates in presence of hydroxide is monitored using an injection cell coupled mass spectrometer at varying temperatures ranging from 30°C to 60°C. The activation energies from the Arrhenius relationship between the CO2 evolution rate and the cell temperature confirms that VC hydrolysis is autocatalytic rather than stoichiometric. Direct quantifications and comparisons of the solubilized reaction products will be done over varying times and temperatures with the help of in-situ nuclear magnetic resonance (NMR) and Raman spectroscopy that will help in clarifying the individual steps in the reaction process. The kinetic studies of EC and VC hydrolysis in model systems like this is an important step towards improving our understanding towards carbonates as there is always some trace amounts of hydroxides present in the cells. The complex interconversions and equilibria of these organic alkyl carbonates and oxides investigated herein, will add to the knowledge of interphase formation processes, and support the tailoring of electrolyte formulations in order to enhance performance of future Li-ion batteries.

Effect of wax chain length on the adhesion dynamics and interfacial rigidity of Salmonella Typhimurium LT2

The wax layer on the surface of fruits and vegetables is the first line of defense against a range of environmental stresses. The initial stage in the etiology of bacterial foodborne illnesses involves the bacterial adhesion and colonization on the wax layer of food commodities. Herein, we report a systematic study that provides new insights into dynamics of interfacial nanoscale processes associated with the transition of bacteria from a planktonic state to a sessile state at the early stages. To achieve this, we coated a piezoelectric sensor with model waxes containing linear alkyl carbon chains of varying lengths (from 6 to 18 carbons) via chemisorption. The process of bacterial adhesion to these wax-coated sensors was monitored using the Quartz Crystal Microbalance with Dissipation (QCM-D) technique, which offers nanogram-level gravimetric accuracy and millisecond time resolution. Our findings revealed that surfaces with higher hydrophobicity are more susceptible to Salmonella adhesion. Furthermore, we conduct a comparative analysis of the viscoelastic properties of the adhered layer, revealing distinct behaviors: Salmonella adhered to C6-wax exhibited solid-like characteristics, while adherence to C18-wax rendered a more liquid-like response. This observation underscores the role of interfacial energy in governing bacterial adhesion, as interpreted through the thermodynamic and surface science model, ultimately influencing rigidity. This investigation offers valuable insights into the initial adhesion to surfaces and has potential implications for surface design and modification within the food industry and other relevant applications, while also contributing to our understanding of bacterial contamination in food commodities.

Computational insights into the spontaneity of epoxide formation from halohydrins and other mechanistic details of Williamson’s ether synthesis

The reaction mechanism of several Williamson‟s ether syntheses have been studied using density functional theory with triple-ζ basis sets. These computations show that the synthesis of geometrically-strained epoxide from deprotonated halohydrins is due to the combined effects of favourable solvation of the products, higher bond enthalpy of C-O bonds vs. C-Cl bonds and increased vibrational entropy of the epoxide vs. the original halohydrin. Examination of the pathways leading to the formation of larger cyclic ethers revealed that the experimentally-observed preference for the formation of five-atom rings over six-atom-rings is due to the preference of the intervening methylene groups for staggered conformations, which entails that the alkyl carbon in the reactant state leading to the six-atom cyclic ether is initially not properly aligned with the attacking alkoxide. Study of the competing elimination reactions further shows that during the synthesis of five-atom cyclic ethers the competing elimination reaction is strongly disfavoured due to steric effects. The temperature dependence of both reactions favours elimination over SN2 as temperature rises, though only when the alkoxide and the halogen moieties are not part of the same carbon chain.

Effects of stratified mining on the low-temperature oxidation and physicochemical properties of lower coal layers

To investigate the impact of stratified mining on the spontaneous combustion characteristics of lower coal in thick coal seams, an analysis was conducted on the macro pore structure, temperature rise, oxygen consumption characteristics, chemical structure, surface chemical properties, and functional group distribution of the upper and lower stratified coal samples (LSC, LSR) from the LinSheng Mine 1202 re-mining face. Post re-mining, the specific surface area, average pore diameter for adsorption, micropore volume, and mesopore volume of LSR showed a significant increase compared to LSC. The maximum mass loss rate for LSR was approximately three times that of LSC, and the characteristic temperature of LSR was lower. When the volumetric fraction of oxygen exceeded 12%, the oxygen consumption rate and CO generation rate of LSR surpassed those of LSC. The alkyl carbon content in LSR was 2% lower compared to LSC, while the oxygenated carbon content was higher by 4.37%. The oxygen content in LSR and the O/C ratio were higher than those in LSC. The structural order of LSR was lower by 11.3%, and the oxygen-containing functional groups were higher by 1.15%. These findings suggest that stratified mining increases the spontaneous combustion risk of lower coal layers. This study underscores the need for careful consideration of mining strategies to mitigate potential risks.

Emulsion polymerization of super-hydrophobic acrylate enabled by a novel “ferrying” strategy for developing waterborne coatings with reduced surface tension and glossiness

The emulsion polymerization of high-alcohol acrylates with extreme hydrophobicity while achieving high monomer conversion has been posed significant challenges. In this study, the emulsion copolymerization of super-hydrophobic stearyl acrylate (SA) with an 18-carbon alkyl group has been successfully conducted by a novel “ferrying” strategy. Specifically, an emulsifier with a 23-carbon alkyl group (hydrophobic) and a 20-oxethyl group (hydrophilic) simultaneously was designed to facilitate the efficient transfer of SA through hydrophobic interaction from monomer drops to micelles, leading to a remarkable improvement in monomer conversion. The self-migration of the 18-carbon alkyl groups grafted onto the copolymer chains, which moved from the inner matrix to the coating surface, resulted in the creation of the waterborne coating with low surface tension during the film formation process. Moreover, it was confirmed that the self-crystallization of the 18-carbon alkyl groups caused the coating to exhibit a self-matting effect with low glossiness. Using an industrial formula, the effects of different types and dosages of emulsifiers, as well as the dosage of SA, on the total monomer conversion, SA conversion, and coating properties were extensively investigated. This work not only broadens the monomer range for emulsion polymerization to highly hydrophobic species, but also provides a variety of industrial waterborne products with low surface tension and low glossiness derived from high-alcohol acrylates, contributing to the development of environmentally friendly chemical industries.

Tailoring chemical composition of solid electrolyte interphase by selective dissolution for long-life micron-sized silicon anode

Micron-sized Si anode promises a much higher theoretical capacity than the traditional graphite anode and more attractive application prospect compared to its nanoscale counterpart. However, its severe volume expansion during lithiation requires solid electrolyte interphase (SEI) with reinforced mechanical stability. Here, we propose a solvent-induced selective dissolution strategy to in situ regulate the mechanical properties of SEI. By introducing a high-donor-number solvent, gamma-butyrolactone, into conventional electrolytes, low-modulus components of the SEI, such as Li alkyl carbonates, can be selectively dissolved upon cycling, leaving a robust SEI mainly consisting of lithium fluoride and polycarbonates. With this strategy, raw micron-sized Si anode retains 87.5% capacity after 100 cycles at 0.5 C (1500 mA g−1, 25°C), which can be improved to >300 cycles with carbon-coated micron-sized Si anode. Furthermore, the Si||LiNi0.8Co0.1Mn0.1O2 battery using the raw micron-sized Si anode with the selectively dissolved SEI retains 83.7% capacity after 150 cycles at 0.5 C (90 mA g−1). The selective dissolution effect for tailoring the SEI, as well as the corresponding cycling life of the Si anodes, is positively related to the donor number of the solvents, which highlights designing high-donor-number electrolytes as a guideline to tailor the SEI for stabilizing volume-changing alloying-type anodes in high-energy rechargeable batteries.