Hydrogen Fluoride Research Articles

Eliminating Hydrogen Fluoride through Piperidine‐Doped Separators for Stable Li Metal Batteries with Nickel‐Rich Cathodes

AbstractHydrofluoric acid (HF)‐induced electrode and interfacial structure degeneration poses a significant challenge for high‐voltage lithium metal batteries (LMBs). To address this issue, we propose a separator strategy that involves decorating a regular polyethylene (PE) separator with molecular sieves (TW) impregnated with piperidine (PI). The porous structure of the TW serves as a reaction chamber for PI and HF. As a result, the HF content in the controlled electrolyte with 500 ppm H2O (ELE‐500) is notably reduced when using TW@PI‐PE separators, thereby shielding nickel‐rich cathodes from HF etching. Simultaneously, due to the hydrolysis of Li salts, and the inertness of PI towards H2O, a uniform lithium fluoride (LiF)‐rich solid electrolyte interphase can form on the Li metal anode, further mitigating dendrite formation. The lifespan of the symmetric Li cell using the TW@PI‐PE separator is doubled in ELE‐500, exhibiting stable 500‐hour cycles at 3 mA cm−2 and 3 mAh cm−2. Additionally, with the effective limitation of transition metal (TM) dissolution, the 4.6‐V LMBs employing a LiNi0.8Co0.1Mn0.1O2 cathode maintain an 81 % capacity retention over 100 cycles, even in ELE‐1000. The innovative TW@PI system presented here offers a fresh perspective for future research aimed at eliminating HF in LMBs.

Nanoporous Structure Fabrication on Glass Surfaces for Enhanced Glass Adhesion Using Hydrogen Fluoride Gas.

The bonding between glass and other materials plays a crucial role when glass is used in industrial products. In this study, we propose a new approach to enhance the bonding strength of glass with other materials by fabricating nanoscale porous structures on glass surfaces via a chemical reaction with hydrogen fluoride gas. Herein, we present a methodology for controlling the thickness of the porous structure, clarify the relationship between the thickness and adhesion strength, investigate the shape of the formed porous structure, and propose a method to control its shape. Our findings reveal that the fabricated porous structure greatly improves the adhesion strength of the adhesive owing to the microscopic anchoring effect induced by the penetration of the adhesive into the porous structure. This approach is expected to be applied to architectural and automobile window glasses, solar panels, sensor cover glasses of autonomous vehicles, display devices (including smartphones), and wearable devices.

UMRSF-TDDFT: Unrestricted Mixed-Reference Spin-Flip-TDDFT.

An unrestricted version of Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (UMRSF-TDDFT) was developed based on unrestricted Kohn-Sham orbitals (UKS) with a new molecular orbital (MO) reordering scheme. Additionally, a simple yet accurate method for estimating ⟨S2⟩ expectation values was devised. UMRSF-TDDFT was benchmarked against cases where DFT, TDDFT, and SF-TDDFT traditionally fail to provide accurate descriptions. In an application to the ground and excited states of a Be atom, UMRSF-TDDFT successfully recovers the degenerate states, with its energies slightly reduced compared to its RO counterpart, due to the additional variational flexibility of UKS. A clear difference between UMRSF and U-SF-TDDFT is evident in the bond breaking of the hydrogen fluoride system, as the latter misses an important configuration. In the case of the Jahn-Teller distortion of trimethylenemethane (TMM), the relative singlet energy compared to the triplet is lower by 0.1 and 0.2 eV for UMRSF and U-SF-TDDFT, respectively, than that of MRSF-TDDFT. The reduction in UMRSF energy is attributed to spatial orbital relaxations, whereas the reduction in U-SF-TDDFT energy results from spin contamination. Overall, the additional orbital relaxations afforded by unrestricted Kohn-Sham (UKS) orbitals in UMRSF-TDDFT lead to lower total system energies compared to their restricted open-shell counterparts. This enhancement adds a practical and accurate quantum chemical theory to the existing RO variant for addressing challenging systems where traditional quantum theories suffer.

Characterization of Lithium-Ion Battery Fire Emissions—Part 2: Particle Size Distributions and Emission Factors

The lithium-ion battery (LIB) thermal runaway (TR) emits a wide size range of particles with diverse chemical compositions. When inhaled, these particles can cause serious adverse health effects. This study measured the size distributions of particles with diameters less than 10 µm released throughout the TR-driven combustion of cylindrical lithium iron phosphate (LFP) and pouch-style lithium cobalt oxide (LCO) LIB cells. The chemical composition of fine particles (PM2.5) and some acidic gases were also characterized from filter samples. The emission factors of particle number and mass as well as chemical components were calculated. Particle number concentrations were dominated by those smaller than 500 nm with geometric number mean diameters below 130 nm. Mass concentrations were also dominated by smaller particles, with PM1 particles making up 81–95% of the measured PM10 mass. A significant amount of organic and elemental carbon, phosphate, and fluoride was released as PM2.5 constituents. The emission factor of gaseous hydrogen fluoride was 10–81 mg/Wh, posing the most immediate danger to human health. The tested LFP cells had higher emission factors of particles and HF than the LCO cells.

Assessment of the public health risk caused by exposure to atmospheric emissions from an aluminum plant

Introduction. Aluminum production is accompanied by emissions of pollutants that can negatively affect the environment and public health. The study aims to determine the impact of atmospheric emissions from an aluminum plant on the health of the population of the city of Novokuznetsk based on a risk assessment. Materials and methods. The volume of maximum permissible emissions of the Novokuznetsk Aluminum Plant was used in the work. Experts calculated the maximum and average concentrations of substances at 40 exposure points. The maximum permissible concentrations of substances were determined in accordance with SanPiN 1.2.3685-21. The authors calculated the carcinogenic risk and the risk of non-carcinogenic effects in accordance with the Guidelines 2.1.10.1920-04. They carried out the classification of risk levels based on methodological recommendations 2.1.10.0156-19. 2.1.10. Results. The authors have selected pollutants were for risk assessment: inorganic dust with a SiO2 content of <20%, sulfur dioxide, benz(a)pyrene, hydrogen fluoride, carbon monoxide, nitrogen dioxide, suspended solids, nitrogen oxide, carbon (soot). The maximum concentrations were 0.1–3.77 MPC for inorganic dust (SiO2<20%), 0.1–2.64 MPC for hydrogen fluoride and 0.05–1.74 MPC for sulfur dioxide; average concentrations were up to 9.16 MPC for benz(a)pyrene. The hazard indices for acute exposure are at an acceptable level; For chronic exposures, they correspond to alarming and high levels, reaching the highest value (13.469) at a point located closer to the sources of emissions. Hazard indices for critical organs and systems in acute exposures are at acceptable or minimum (target) levels, in chronic exposures they correspond to alarming and high-risk levels. The respiratory and immune systems are most affected. The total individual carcinogenic risk ranges from 4×10–7 to 8×10–6, without exceeding the upper limit of the permissible risk. Residents of the Kuznetsk district of the city are most affected by emissions. Limitations. The main limitation in the work carried out was the use of calculated concentrations of pollutants for risk assessment without the use of in-kind indicators. Conclusion. Elevated concentrations of pollutants were detected in the atmospheric air of residential areas adjacent to the territory of the aluminum plant, which determine alarming and high levels of non-carcinogenic risk to public health. Ethics. This study did not require the conclusion of the Ethics Committee.

On the moisture tolerance of LiFSI based lithium-ion batteries: A systematic study on NMC622/graphite full cells

Lithium-ion battery (LIB) technology is state-of-the-art energy storage technology for portable electronics and electric vehicles (EVs). In this incumbent LIB technology, lithium hexafluorophosphate (LiPF6) is the most widely used electrolyte salt to date. However, the challenges related to its chemical/thermal stability, sensitivity to moisture and the consequent formation of strong acids such as hydrogen fluoride (HF) need to be resolved with alternative salts. Due to its better chemical/thermal stability, resistance to moisture and HF formation, and better ionic conductivity, lithium bis(fluorosulfonyl)imide (LiFSI) has been considered as a promising alternative electrolyte salt to LiPF6. In this study, the effect of addition of 1000 ppm water on LiFSI based electrolytes was systematically investigated by testing NMC622/lithium and artificial graphite/lithium half and NMC622/graphite full cells in four LiFSI based electrolytes; plain LiFSI, LiFSI + 1000 ppm H2O, LiFSI + 10 wt% FEC, and LiFSI + 1000 ppm H2O + 10 wt% FEC. Post mortem characterization of selected electrodes was also conducted with SEM imaging and XPS to study the surface chemistry and morphology of cycled electrodes. Overall, this study shows that 1000 ppm water can slightly improve the electrochemical performance of NMC622/lithium half cells; however, the same amount of moisture severly degrades the graphite half and NMC622/graphite full cells.

The Effect of Fluorine and Hydrogen Concentrations on the Chain Reaction of HF Chemical Laser

A numerical investigation has been performed to examine the effect of fluorine concentration on the chain reaction mechanisms and parameters of hydrogen fluoride (HF) chemical laser. The practical difficulties associated with this type of lasers impose that an alternative route might be quite useful. Thus, particular attention was paid to develop a computer program to investigate various processes. The results of this computer simulation program proved their credibility when compared with the little published data. This computer program is called Reaction Rate Simulation Model (RRSM). An entirely new approach to emulate the reaction mechanisms has been followed. The effectiveness of reaction rates in the processes of HF laser production has been investigated. This simulation program dealt with the percentages of the forward and reverse reactions, when a large number of reactions have been considered. In addition a large number of species have been taken into account in these reactions. From the computer program (RRSM), some valuable results could be predicted with regard to the hydrogen fluoride chemical laser.

Boc/Bzl Solid-Phase Synthesis of Deltorphin II and Its Analogs without the Utilization of Anhydrous Hydrogen Fluoride

Boc/Bzl Solid-Phase Synthesis of Deltorphin II and Its Analogs without the Utilization of Anhydrous Hydrogen Fluoride

Effect of sensing material basicity on excited-state intramolecular proton transfer-based detection of G-series nerve agents

The use of G-series nerve agents represents a significant threat and there is a need for rapid and selective in-field identification. We report that sensing materials composed of ESIPT-based silyl ethers can be used to detect the hydrogen fluoride that is present in phosphonofluoridate agents such as sarin and its simulant di-iso-propyl fluorophosphate (DFP). We find that the ability of the sensing material to detect the hydrogen fluoride in DFP is dependent on the basicity of the nitrogen atom that forms part of the ESIPT moiety upon deprotection. When the pKa of the conjugate acid of the nitrogen atom was lower than that of hydrogen fluoride the ability of the sensing material to detect the acid and hence simulant was curtailed. However, when the pKa of the conjugate acid was 3 or higher, then hydrogen fluoride could be rapidly detected. The best performing sensing material could detect hydrogen fluoride concentrations as low as 3 ppb in DFP of 99 % purity in one minute. Based on sarin having the same purity level, we estimate that it would be detectable at a concentration of ≈40 ppb in one minute, which is lower than the Acute Exposure Guideline 3 (life-threatening effects) of 64 ppb for a 10-min exposure.

Experimental study on high temperature gaseous hydrogen fluoride corrosion of boiler water-cooled wall pipes

ABSTRACT Hydrogen fluoride (HF) corrosion of boiler water-cooled wall pipes at high temperature hinders the co-disposal of fluorinated hazardous wastes and coal by combustion. In this paper, common water-cooled wall pipes (15CrMoG and 20G) were utilized to perform gaseous HF corrosion experiments at high temperature on a horizontal tube furnace. The effects of temperature on HF corrosion of different water-cooled wall pipes in 0.2% HF were investigated. Corrosion kinetics curve was obtained by calculating the mass increase due to corrosion. The microscopic morphology and physical phase composition of water-cooled wall pipes after HF corrosion were analyzed. The corrosion resistances of the two water-cooled wall pipes decrease with increasing the temperature. The corrosion weight gain curves of 15CrMoG and 20G at 550 ℃ are ΔW 1.9144 = 0.2100t and ΔW 1.8356 = 0.1344t, respectively. The average corrosion rates of 15CrMoG and 20G are 0.0177 and 0.0125 mg/(cm2·h), respectively. The corrosion resistance of 15CrMoG is superior compared to 20G. The HF corrosion at high temperature consists of non-alternating fluorination and oxidation of the metal matrix. This study is of great significance for the protection of boilers with HF corrosion at high temperature.

Molecular Dynamics Simulation Model of Alkali Metal Reduction of Gaseous Halides and Reaction Mechanism Analysis.

The reaction of gaseous hydrogen halides with alkali metals provides a new pathway for producing hydrogen. The structure and reactivity of alkali metals are crucial for the reduction of gaseous halides. However, traditional gas-phase reaction models fail to provide insights into the dynamic processes occurring during alkali metal reactions. In this paper, based on the reaction between Hydrogen fluoride (HF) and alkali metal sodium (Na), we have established a metallic Na slab. HF molecules were randomly inserted above the surface of the Na slab, creating a reaction model for the reduction of HF by metallic Na. The reaction of HF on the Na surface was calculated using first-principles molecular dynamics. The configuration and reaction of the Na surface and HF molecules at different times were judged by analyzing the radial distribution function and mean squared displacement. Na atoms reacted with HF to produce intermediate NaFH, and then the F-H bond broke to form NaF and H. The F-H bond breaking of intermediate NaFH was the key step, and the kinetic parameters of this key step were calculated.

Application of Response Surface Methodology for concentration of fluorosilicic acid by extraction technique with benzyl alcohol as extractant

As a kind of alternative of natural fluorinated minerals and raw material for producing anhydrous hydrogen fluoride, fluorosilicic acid has attracted more and more attention. In order to raise its utilization rate, dilute fluorosilicic acid solution coming from chemical enterprises needs to be concentrated. The extraction technology with benzyl alcohol as extraction agent was used to concentrating fluorosilicic acid aqueous solution. In order to determine the optimizing operation conditions of the extracting process, single - factor experiments were carried out to confirm the significant affecting factors and their operating range. Then the Response Surface Methodology (RSM) was conducted to accomplish regression of a nonlinear quadratic polynomial model to the experimental data and statistical analysis. Based on these studies, the optimal technical parameters of extracting process are acquired by optimization of the model using the Design-Expert 13 software. The statistical analysis for the fitting response surface quadratic equation model indicated that the model was reliable and accurate with very low p-values (<0.0001), the predicted values with the model equation had remarkable consistency in experimental data. By a great number of optimizations carried out with the Design Expert 13 software based on the fitting model equation, the optimal extractive processing conditions for concentrating fluorosilicic acid aqueous solution were obtained: the phase ratio 7, the extraction time 120.11 min and the extraction temperature 39.70 °C. The optimal concentration of fluorosilicic acid is 26.68 %. In order to increase the concentration of fluorosilicic acid, three-stage cross-current extraction for dilute fluorosilicic acid solution was carried out at the optimizing extracting conditions, 17.43 wt% fluorosilicic acid solution can be concentrated up to 37.46 wt%. The extractant-benzyl alcohol can be recovered with vacuum distillation and recovery rate reached up to 98 %.

The impact of export controls on international trade: Evidence from the Japan–Korea trade dispute in semiconductor industry

In July 2019, the Japanese government announced export controls to South Korea of three chemical inputs essential in semiconductor production. This paper investigates the short- to middle-run effect of the Japan–Korea export controls on the trade patterns of the restricted and other related products of the semiconductor industry. The results show that the export controls caused a large decline in Japanese exports to South Korea of one of the three restricted inputs, hydrogen fluoride, but not in the other two restricted inputs, photoresist and fluorinated polyimide. Second, South Korea reallocated the sourcing of the restricted chemical inputs from Japan to other economies such as Belgium, the U.S., and Taiwan. Third, there was negative spillover effect on the South Korean imports of semiconductor manufacturing equipments, which is used complementarily with the restricted inputs in the semiconductor production. These results suggest a potential role of export controls in sourcing patterns and production relocation in the semiconductor industry.

Plasma simulation of HF plasma generated in dual-frequency chamber for high aspect ratio dielectric etching

For the 3D NAND memory hole with a high aspect ratio above 100, the etching process with hydrogen-fluoride (HF) contained plasmas has been proposed. We have developed a simulation model for gas-phase reactions that reproduces the HF plasma in experiments. The HF plasma was generated using a power supply of 100 MHz frequency, and electron and F densities were measured. The simulation model was constructed on the basis of the collision cross sections and reaction constants reported in the previous papers, and the F density in the simulation was calibrated by comparing it with that in the experiments. As a result of the plasma simulation, the densities of F and the electrons were determined to be 7.52 × 1016 m–3 and 8.50 × 1016 m–3, respectively. Taking into consideration the errors in the experiment, we considered that the simulation model is able to reproduce the experimental HF plasma well.

Adsorbtive removal of HF toxic gas via tinsulfide monolayer modification: A molecular perspective

Hydrofluoric Acid (HF) is considered one of the most hazardous chemicals used in industrial plants. Even small exposures to HF can have fatal consequences if not promptly and properly treated. Various research teams have presented numerous substances with the objective of capturing or detecting toxic HF gas. In this study, we explore the impact of HF gas on a single layer of SnS by employing density functional theory (DFT). The interaction nature between the gas molecule and the adsorbent is elucidated by analyzing the related adsorption energy, electronic structure properties and differential charge transfer. The findings indicate that HF is physically adsorbed on the pristine SnS with an adsorption energy value of −0.63 eV. By introducing a Sn mono vacancy defect, the modification of SnS enhances the adsorption energy to −1.26 eV, resulting in a chemisorption process. Molecular fluorine (F2) was discovered to undergo a barrierless reaction with SnS, resulting in the formation of fluorine-substituted SnS. It has been discovered that the substitution of fluorine atoms enhances the reactivity of SnS towards hydro-gen fluoride gas. The adsorption potential of the studied structures towards HF gas was determined to be in the following order: F2SnS > VSn–SnS > VS-SnS ∼ SnS. The current study is anticipated to offer new molecular insights that could lead to the creation of innovative devices for detecting or eliminating HF toxic gas from a specific atmosphere.

Eliminating Hydrogen Fluoride through Piperidine-Doped Separators for Stable Li Metal Batteries with Nickel-Rich Cathodes.

Hydrofluoric acid (HF)-induced electrode and interfacial structure degeneration poses a significant challenge for high-voltage lithium metal batteries (LMBs). To address this issue, we propose a separator strategy that involves decorating a regular polyethylene (PE) separator with molecular sieves (TW) impregnated with piperidine (PI). The porous structure of the TW serves as a reaction chamber for PI and HF. As a result, the HF content in the controlled electrolyte with 500 ppm H2O (ELE-500) is notably reduced when using TW@PI-PE separators, thereby shielding nickel-rich cathodes from HF etching. Simultaneously, due to the hydrolysis of Li salts, and the inertness of PI towards H2O, a uniform lithium fluoride (LiF)-rich solid electrolyte interphase can form on the Li metal anode, further mitigating dendrite formation. The lifespan of the symmetric Li cell using the TW@PI-PE separator is doubled in ELE-500, exhibiting stable 500-hour cycles at 3 mA cm-2 and 3 mAh cm-2. Additionally, with the effective limitation of transition metal (TM) dissolution, the 4.6-V LMBs employing a LiNi0.8Co0.1Mn0.1O2 cathode maintain an 81% capacity retention over 100 cycles, even in ELE-1000. The innovative TW@PI system presented here offers a fresh perspective for future research aimed at eliminating HF in LMBs.

Effect of a novel low-concentration hydrogen peroxide bleaching gel containing nano-sized sodium trimetaphosphate and fluoride

ObjectivesTo evaluate in vitro the effects of nano-sized sodium trimetaphosphate (TMPnano) and sodium fluoride (F) added to a 17.5 % hydrogen peroxide (H2O2) bleaching gel on the color change, enamel mechanical and morphological properties, and H2O2 transamelodentinal diffusion. Materials and MethodsBovine enamel/dentin discs (n = 180) were divided according to the bleaching gel: 17.5 % H2O2 (17.5 % HP); 17.5 % H2O2 + 0.1 % F (HP/F); 17.5 % H2O2 + 1 % TMPnano (HP/TMPnano); 17.5 % H2O2 + 0.1 % F + 1 % TMPnano (HP/F/TMPnano) and 35 % H2O2 (35 % HP). The gels were applied for 40 min on three sessions, each session spaced 7 days apart. The total color change (ΔE*ab) according to the Commission Internationale de l'Eclairage (CIE) L*a*b* color change measured by CIEDE2000 (ΔE00), whitening index (ΔWID), surface hardness (SH), surface roughness (Ra), cross-sectional hardness (ΔKHN), and transamelodentinal diffusion were assessed. Enamel surfaces were examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDS) analysis. The data were analyzed using ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). ResultsΔE*ab, ΔE00, and ΔWID values were comparable among the gels that produced a bleaching effect post-treatment (p < 0.001). The HP/F/TMPnano group exhibited lower mineral loss (SH and ΔKHN), Ra, and H2O2 diffusion compared to the 17.5 % HP and 35 % HP groups, which had the highest values (p < 0.001). SEM/EDS analysis revealed surface changes in all bleached groups, though these changes were less pronounced with F/TMPnano. ConclusionsThe 17.5 % HP gel containing F/TMPnano maintains the bleaching effect while reducing enamel demineralization, roughness, H2O2 diffusion, and enamel morphological changes. Clinical RelevanceLow-Concentration H2O2 bleaching gel containing F/TMPnano can be used as a novel approach to enhance safety and maintain the performance of aesthetic effects.

Thallium-Fluorides Revisited: Crystal Chemistry of TlHF2, Tl2[MF6]·2TlF, and Tl2[MF6]·TlCl (M = Si and Ge).

Although the formation of thallium hydrogen fluorides TlHxFx+1 (x = 1, 1.5, 2, 3, 5, 6.5, and 7) from TlF and HF was reported in the 1970s, little is known about the corresponding crystal structures. To shed light on the crystal chemistry of the thallium fluorides, we reinvestigated the structure of α-TlHF2, which was obtained by crystallization of TlF from 50% HF at room temperature. We disclose that β-TlHF2 is isostructural with α-MHF2 (M = K, Rb, and Cs), γ-TlHF2 is isostructural with β-MHF2 (M = K and Rb), whereas α-TlHF2 crystallizes in an unusual structure type. During the reaction of TlHF2 with the glass of the microscope slide, crystals of the previously unknown compound Tl2[SiF6]·2TlF were formed. We disclose that the related Tl2[GeF6]·2TlF can be obtained by the crystallization of stoichiometric amounts of Tl2[GeF6] with TlF from water at room temperature. The crystal structures of α-TlHF2, Tl2[SiF6]·2TlF, Tl2[SiF6]·TlCl, Tl2[GeF6]·2TlF, Tl2[GeF6]·TlCl, and Tl2[GeF6] were determined by single-crystal X-ray diffraction analysis. The crystal structures of α-TlF and Tl2[SiF6]·xTlF (x = 0, 1) were redetermined at low temperatures.

Ultrathin ZrO2 thickness control on TiO2/ZrO2 core/shell nanoparticles using ZrO2 atomic layer deposition and etching

Atomic layer deposition (ALD) and atomic layer etching (ALE) techniques were used to control the ZrO2 shell thickness on TiO2/ZrO2 core/shell nanoparticles. ALD and ALE were performed at 200 °C while the nanoparticles were agitated using a rotary reactor. To increase the ZrO2 shell thickness, ZrO2 ALD films were deposited using sequential exposures of tetrakis(dimethylamino) zirconium and H2O. Ex situ analysis using transmission electron microscopy (TEM) observed the growth of the ZrO2 shells. The ZrO2 ALD led to more spherical ZrO2 shells on the crystalline and irregular TiO2 cores. The ZrO2 ALD on the nanoparticles had a growth rate of 0.9 ± 0.1 Å/cycle. Tunable ZrO2 coatings were observed with thicknesses ranging from 5.9 to 27.1 nm after 240 ZrO2 ALD cycles. To demonstrate the decrease in the ZrO2 shell thickness, the ZrO2 film was then etched using sequential hydrogen fluoride (HF) and TiCl4 exposures. Quadrupole mass spectrometry experiments performed in a separate reactor identified the volatile products during ZrO2 ALE. H2O was monitored during HF exposures, and ZrCl4 etch products and TiFxCly ligand-exchange products were observed during TiCl4 exposures. Ex situ TEM studies revealed that the ZrO2 shells remained spherical during ZrO2 ALE. The ZrO2 ALE on the nanoparticles had an etch rate of 6.5 ± 0.2 Å/cycle. Tunable ZrO2 coatings were produced from 27.1 down to 7.6 nm using 30 ZrO2 ALE cycles. This study demonstrated that ZrO2 ALD and ZrO2 ALE can control the thickness of ZrO2 shells on TiO2/ZrO2 core/shell nanoparticles without inducing nanoparticle agglomeration.

Revealing the interfacial chemistry of silicon anodes with polysiloxane electrolyte additives

Silicon (Si) anodes are promising in lithium-ion batteries owing to their high specific capacity and suitable voltage platform. However, particle volume expansion (>300 %) and the continuous consumption of Li+ to form new interfacial layers result in poor cycle performance. We report a sustainable low-cost Si material derived from photovoltaic cutting waste, showing a high initial Coulombic efficiency (86.9 %). The cycle stability of Si/graphite is enhanced in terms of a 38 % capacity retention increase in the presence of vinyl-terminated polydimethylsiloxane (Vi-PDMS) additive. The C = C bond in Vi-PDMS plays a role in reacting with hydrogen fluoride (HF) by-products to prevent the side reaction between HF and solvent. The decomposed macromolecule Si-containing Li salt serves as a part of the solid electrolyte interphase film and has low interface resistance. This formed interphase layer effectively mitigates stress concentration at the contact surface between silicon particles and the current collector caused by expansion forces.