Search Results (163)

In this work, graphite anodes and lithium iron phosphate (LFP) cathodes are used to examine the effects of sodium hexafluorophosphate (NaPF₆) and potassium hexafluorophosphate (KPF₆) electrolyte additives on the formation of the solid electrolyte interphase and the performance of lithium-ion batteries in both half-cell and full-cell designs. The objective is to assess whether these additives may increase cycle performance, decrease irreversible capacity loss, and improve interfacial stability. Compared to the control electrolyte (1.22 M Lithium hexafluorophosphate (LiPF₆)), cells with NaPF₆ and KPF₆ additives produced less SEI products, which decreased irreversible capacity loss and enhanced initial coulombic efficiency. Following the formation of the solid electrolyte interphase, the specific capacity of the control cell was 607 mA·h/g, with 177 mA·h/g irreversible capacity loss. In contrast, irreversible capacity loss was reduced by 38.98% and 37.85% in cells containing KPF₆ and NaPF₆ additives, respectively. In full cell cycling, a considerable improvement in capacity retention was achieved by adding NaPF₆ and KPF₆. The electrolyte, including NaPF₆, maintained 67.39% greater capacity than the LiPF₆ baseline after 20 cycles, whereas the electrolyte with KPF₆ demonstrated a 30.43% improvement, indicating the positive impacts of these additions. X-ray photoelectron spectroscopy verified that sodium (Na⁺) and potassium (K⁺) ions were present in the SEI of samples containing NaPF₆ and KPF₆. While K⁺ did not intercalate in LFP, cyclic voltammetry confirmed that Na⁺ intercalated into LFP with negligible impact on the energy storage of full cells. These findings demonstrate that NaPF₆ and KPF₆ are suitable additions for enhancing lithium-ion battery performance in the popular artificial graphite/LFP system. Full article

A 12-membered pyridinophane scaffold containing two pyridine and two tertiary amine residues is examined as a prototype ligand (^tBuN4) for supporting nitrene transfer to olefins. The known [(^tBuN4)M^II(MeCN)₂]²⁺ (M = Mn, Fe, Co, and Ni) and [(^tBuN4)Cu^I(MeCN)]⁺ cations are synthesized with the hexafluorophosphate counteranion. The aziridination of para-substituted styrenes with PhI=NTs (Ts = tosyl) in various solvents proved to be high yielding for the Cu(I) and Cu(II) reagents, in contrast to the modest efficacy of all other metals. For α-substituted styrenes, aziridination is accompanied by products of aziridine ring opening, especially in chlorinated solvents. Bulkier β-substituted styrenes reduce product yields, largely for the Cu(II) reagent. Aromatic olefins are more reactive than aliphatic congeners by a significant margin. Mechanistic studies (Hammett plots, KIE, and stereochemical scrambling) suggest that both copper reagents operate via sequential formation of two N–C bonds during the aziridination of styrene, but with differential mechanistic parameters, pointing towards two distinct catalytic manifolds. Computational studies indicate that the putative copper nitrenes derived from Cu(I) and Cu(II) are each associated with closely spaced dual spin states, featuring high spin densities on the nitrene N atom. The computed electrophilicity of the Cu(I)-derived nitrene reflects the faster operation of the Cu(I) manifold. Full article

High-power lithium-ion batteries impose stringent requirements on output power. Tetramethylene sulfone (TMS), serving as a novel electrolyte additive, effectively enhances the stability of electrolytes under high-voltage conditions due to its high flash point and high dielectric constant, thereby boosting the output performance of lithium-ion batteries. In this work, we selected lithium hexafluorophosphate (LiPF₆) as the lithium salt, using a solvent carrier consisting of a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). TMS was added as an additive to create a novel high-power electrolyte system. We prepared five electrolytes with different TMS concentrations and conducted in-depth investigations into their impacts on the performance of lithium-ion batteries. The findings indicate that the electrolytes with TMS ratios of 2 wt% and 5 wt% demonstrated good synergistic cathode–anode stability in the NCM//soft carbon system, and the electrolyte with a 5 wt% TMS ratio demonstrated the most significant improvement in the overall performance of the full battery. Full article

The paper shows the effect of using a lubricant in the form of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆), on the tribological properties of a hydrogenated diamond-like coating (DLC) doped with tungsten a-C:H:W. The coatings were deposited on 100Cr6 steel by plasma-enhanced chemical vapor deposition PECVD. Tribological tests were carried out on a TRB³ tribometer in a rotary motion in a ball–disc combination. 100Cr6 steel balls were used as a counter-sample. Friction and wear tests were carried out for discs made of 100Cr6 steel and 100Cr6 steel discs with a DLC coating. They were performed under friction conditions with and without lubrication under 10 N and 15 N loads. The ionic liquid BMIM-PF₆ was used as a lubricant. Coating thickness was observed on a scanning microscope, and the linear analysis of chemical composition on the cross-section was analyzed using the EDS analyzer. The confocal microscope with an interferometric mode was used for analysis of the geometric structure of the surface before and after the tribological tests. The contact angle of the samples for distilled water, diiodomethane and ionic liquid was tested on an optical tensiometer. The test results showed good cooperation of the DLC coating with the lubricant. It lowered the coefficient of friction in comparison to steel about 20%. This indicates the synergistic nature of the interaction: DLC coating–BMIM-PF₆ lubricant–100Cr6 steel. Full article

Batteries are used as energy storage devices in various equipment. Today, research is focused on solid-state batteries (SSBs), replacing the liquid electrolyte with a solid separator. The solid separators provide electrolyte stability, no leakage, and provide mechanical strength to the battery. Separators are mostly manufactured by either traditional processes or 3D printing technologies. These processes involve making a slurry of plastic, active and conductive material and usually adding a plasticizer when making thin films or filaments for 3D printing. This study investigates the additive manufacturing of solid-state electrolytes (SSEs) by employing fused deposition modeling (FDM) with recyclable, bio-derived polylactic acid (PLA) filaments. Precise control of macro-porosity is achieved by systematically varying key process parameters, including raster orientation, infill percentage, and interlayer adhesion conditions, thereby enabling the formation of tunable, interconnected pore networks within the polymer matrix. Following 3D printing, these engineered porous frameworks are infiltrated with lithium hexafluorophosphate (LiPF₆), which functions as the active ionic conductor. A tailored thermal sintering protocol is then applied to promote solid-phase fusion of the embedded salt throughout the macro-porous PLA scaffold, resulting in a mechanically robust and ionically conductive composite separator. The electrochemical ionic conductivity and structural integrity of the sintered SSEs are characterized through electrochemical impedance spectroscopy (EIS) and standardized mechanical testing to assess their suitability for integration into advanced solid-state battery architectures. The solid-state separator achieved an average ionic conductivity of 2.529 × 10⁻⁵ S·cm⁻¹. The integrated FDM-sintering process enhances ion exchange at the electrode–electrolyte interface, minimizes material waste, and supports cost-efficient, fully recyclable component fabrication. Full article

This work presents the synthesis and structural characterization of a novel type of biscyclometalated Ir(III) complex, which is equipped with two iodoethynyl moieties on its 2,2′-bipyridine (bpy) ligand. Iodoethynyl moieties represent prominent donor systems for the formation of supramolecular structures via halogen bonding (X-bonding). The synthesis of bis(2-phenylpyridinato)-[4,4′-bis(iodoethynyl)-2,2′-bipyridine]iridium(III) hexafluorophosphate, (2)(PF₆), is straightforward and involves post-complexation iodination, thus expanding the already rich toolbox for performing “chemistry on the complex”. The formation of the iodoethynyl moieties was unequivocally proven by ¹H-NMR spectroscopy, ESI-TOF mass spectrometry, and single-crystal XRD analysis. Full article

In this article, we present experimental and theoretical studies of pyridine derivatives (pyDs) inspired by natural systems to investigate the electron transfer processes occurring in aqueous media and elaborate a theoretical model that adequately predicts the behavior of new derivatives. Our results might be relevant to scientific and technological applications, including energy storage, redox-active scaffolds for organic synthesis, photoredox catalysis, and new materials. The synthesis of eight pyDs is reported. To improve water solubility, six new compounds are hexafluorophosphate alkylammonium salts. The pyDs exhibit irreversible redox processes, with electron-donating substituents decreasing the cathodic peak potential while electron-withdrawing groups increase it; when both substituents are present, the latter effect prevails. A computational study was performed to investigate the electrochemical behavior of the synthesized compounds and design new electroactive pyDs. DFT calculations provided the predominant species’ redox potentials and acidity constants to elaborate Pourbaix diagrams for each compound. The synthesized molecules exhibit a two-electron-one-proton dismutation process in the water pH window. Beyond this range, stabilized radical species undergo one-electron exchange processes. We correlated experimental and calculated parameters, screening 22 additional derivatives to evaluate their electrochemical behavior, identifying potential candidates capable of performing a one-electron transfer process in the pH window of water, revealing new applications for pyDs. Full article

The continuous advancement of technology has led to escalating demands for superior tribological performance in industrial applications, necessitating the enhancement of ceramic materials’ frictional properties through innovative approaches. Solid-lubricant embedding is a widely employed lubrication strategy in metals. However, the challenge of machining holes on ceramic surfaces remains a significant barrier to applying this lubrication technique to ceramics. Gel casting, as a near-net-shaping process, offers several advantages, including uniform green body density, low organic content, and the capability to fabricate components with complex geometries, making it a promising solution for addressing these challenges. In this study, alumina ceramics with small surface holes designed for embedding oil-containing microcapsules were fabricated via gel casting using an N-hydroxy methylacrylamide gel system, which demonstrates lower toxicity compared to conventional acrylamide systems. The fabricated alumina ceramic materials exhibited a high density of 98.2%, a hardness of 16 GPa, and a bending strength of 276 MPa. The oil-containing microcapsules were self-synthesized using hexafluorophosphate ionic liquid as the core material and polyurea-formaldehyde as the wall material. The research results show that under conditions of using an alumina ball, sliding speed of 10 cm/min, load of 5 N, and at room temperature, the material with a microcapsule content of 15 wt% and embedded hole diameter of 1.2 mm reduced the friction coefficient from 0.696 in an unlubricated condition to 0.317. Moreover, the embedding of microcapsules further improved the wear resistance of the alumina. Full article

Excited state intramolecular proton transfer (ESIPT) within molecules in solvents plays important roles in photo-chemistry and photo-biology. Herein, the influence of 1-ethyl-3-methyl-imidazolium bis (trifluoromethylsulfonyl) imide ([EMIm][NTf₂]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF₆]) on the ESIPT of 4′-N,N-diethylamino-3-hydroxyflavone (DEAHF) was explored. The density functional theory and time-dependent density functional theory methodologies were used. The calculated fluorescence spectrum reveals that the fluorescence peaks of DEAHF in [EMIm][NTf₂] and [BMIm][PF₆] originate from the emission of N* and T* forms. The structure’s optimization, infrared spectra, non-covalent interactions and the scanning of potential energy curves collectively demonstrate that the ESIPT of DEAHF likely happen more in [EMIm][NTf₂] than in [BMIm][PF₆]. The solvation effects in [BMIm][PF₆] exhibit greater prominence compared to those in [EMIm][NTf₂], as evidenced by the free energy curve. The alterations in dipole moment indicate a substantial solvation relaxation during the ESIPT processes. Our aforementioned research offers backing for the advancement of novel fluorescent probes. Full article

Hard carbon (HC), which is one of the anode materials widely used in commercial sodium-ion batteries at present, suffers from a thick and unstable solid electrolyte interface (SEI) layer formed by the self-reduction in traditional carbonate-based electrolytes on its surface. This phenomenon impacts the battery’s Coulomb efficiency, cycle stability, and rate performance. In this paper, a pyrrolidinium-type di-cation ionic liquid, butyl-1,4-di(methylpyrrolidinium) di[hexafluorophosphate] (C₄di[mPy].di[PF₆]), is studied as an electrolyte additive to improve the interphase stability of the HC anode. The PF₆⁻ in C₄di[mPy].di[PF₆] enhances the coordination number between Na⁺ and PF₆⁻, and C₄di[mPy]²⁺ is preferentially reduced, jointly participating in the construction of stable, thin, dense and NaF-rich SEI films, thus laying the foundation for improving battery performance. As a result, in the carbonate electrolyte containing 2 wt% C₄di[mPy].di[PF₆], the reversible capacity of the HC/Na half-cell is increased by 14.7%, and the capacity retention rate remains at 90.4% after 400 cycles. This work provides reference for future research and design of high-performance ion liquid additives. Full article

Each battery cell consists of three main components: the anode, the cathode, and the separator soaked with liquid electrolyte, the medium in the battery that allows charged ions to move between the two electrodes. Besides a wide electrochemical stability window and good compatibility with both electrodes, the electrolyte should also be safe, thermally stable and environmentally benign, showing a high ionic conductivity of the charge-carrying Li ions and finally a low price. This unique combination of properties is impossible to achieve with a simple salt–solvent mixture and usually requires a combination of different electrolyte components, i.e., several liquid solvents and additives and one or more conducting salt(s). For lithium-based batteries, which are the most common electrochemical energy storage devices today, a solution based on lithium hexafluorophosphate (LiPF₆) in a mixture of organic carbonates as the solvent is used. Usually, the conducting salt concentrations used for lithium-based electrolytes are in the range of ≈1 to 1.2 M, but recently, electrolytes with much higher conducting salt concentrations of 5 M and even over 10 M have been investigated as they offer several benefits ranging from increased safety to a broadened electrochemical stability window, thus enabling cheap and safe solvents, even water. Full article

Dual-ion batteries (DIBs) were demonstrated as a promising technology for large-scale energy storage due to their low cost, recyclability, and impressively fast charge capability. Graphite as a commonly used cathode material in DIBs, however, suffers from poor compatibility with commercial Li-ion electrolytes and graphite anodes, making it difficult to directly utilize the well-established infrastructure for Li-ion batteries. Herein, we report a small aromatic amine molecule 4,4′,4″-tris(diphenylamino)triphenylamine (N4) functioning as a compatible anion host in the EC-containing Li-ion electrolyte. With an average discharge voltage of 3.6 V (vs. Li⁺/Li), the N4 electrode delivers a reversible specific capacity of 108 mAh/g, which is much higher than 29 mAh/g for the graphite cathode at the same condition. The high capacity retention of 91.3% was achieved after 500 cycles at 1 A/g. The N4 electrode also exhibited good rate performance. Via different characterization techniques like Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, the energy storage mechanism of N4 was revealed as a conversion between amine and quaternary amine cations, accompanied by PF₆⁻ (de-)insertion. As consequences, the assembled N4||graphite DIB w showed a high discharge capacity of 90 mAh/g within 1.5–4.1 V, and good cycling stability with a 98% capacity retention after 40 cycles. Decent rate performance was achieved in the N4||graphite DIB as well. This work provides new insights into designing a compatible anion host for affordable DIBs. Full article

Lithium metal batteries (LiMBs) have emerged as extremely viable options for next-generation energy storage owing to their elevated energy density and improved theoretical specific capacity relative to traditional lithium batteries. However, safety concerns, such as the flammability of organic liquid electrolytes, have limited their extensive application. In the present study, we utilize molecular dynamics and Density Functional Theory based simulations to investigate the Li interactions in gel polymer electrolytes (GPEs), composed of a 3D cross-linked polymer matrix combined with two different non-flammable electrolytes: 1 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in trimethyl phosphate (TMP) solvents. The findings derived from radial distribution functions, coordination numbers, and interaction energy calculations indicate that Li⁺ exhibits an affinity with solvent molecules and counter-anions over the functional groups on the polymer matrix, highlighting the preeminent influence of electrolyte components in Li⁺ solvation and transport. Furthermore, the second electrolyte demonstrated enhanced binding energies, implying greater ionic stability and conductivity relative to the first system. These findings offer insights into the Li⁺ transport mechanism at the molecular scale in the GPE by suggesting that lithium-ion transport does not occur by hopping between polymer functional groups but by diffusion into the solvent/counter anion system. The information provided in the work allows for the improvement of the design of electrolytes in LiMBs to augment both safety and efficiency. Full article

In this study we report on the efficiency of a furane-indole-chromenone-based organic derivative (FIC) as a photocatalyst in the α-arylation of enol acetate upon LED irradiation at 405 nm, and as a photoinitiator/photocatalyst in the free radical polymerization of an acrylate group in the presence of bis-(4-tert-butylphenyl)iodonium hexafluorophosphate (Iod) as an additive, or in the presence of both Iod and ethyl-4-(dimethyl amino) benzoate (EDB) under LED irradiation at 365 nm. The photochemical properties of this new light-sensitive compound are described, and the wide redox window (3.27 eV) and the high excited-state potentials FIC*/FIC^●− (+2.64 V vs. SCE) and FIC^●+/FIC* (−2.41 V vs. SCE) offered by this photocatalyst are revealed. The chemical mechanisms that govern the radical chemistry are discussed by means of different techniques, including fluorescence-quenching experiments, UV-visible absorption and fluorescence spectroscopy, and cyclic voltammetry analysis. Full article

Background: Melanoma is the most aggressive and lethal skin cancer that affects thousands of people worldwide. Ruthenium complexes have shown promising results as cancer chemotherapeutics, offering several advantages over platinum drugs, such as potent efficacy, low toxicity, and less drug resistance. Additionally, anthraquinone derivatives have broad therapeutic applications, including melanoma. Objectives: Thus, two new ruthenium complexes with 1-hydroxy-9,10-anthraquinone were obtained: trans-[Ru(HQ)(PPh₃)₂(bipy)]PF₆ (1) and cis-[RuCl₂(HQ)(dppb)] (2), where HQ = 1-hydroxy-9,10-anthraquinone, PPh₃ = triphenylphospine, bipy = 2,2′-bipyridine, PF₆ = hexafluorophosphate, and dppb = 1,4-bis(diphenylphosphine)butane. Methods: The complexes were characterized by infrared (IR), UV–vis, ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopies, molar conductivity, cyclic voltammetry, and elemental analysis. Furthermore, density functional theory (DFT) calculations were performed. Results: Compound (2) was determined by single-crystal X-ray diffraction, which confirms the bidentate coordination mode of HQ through the carbonyl and phenolate oxygens. Additionally, DNA-binding experiments yielded constants of 10⁵ M⁻¹ (Kb = 6.93 × 10⁵ for (1) and 1.60 × 10⁵ for (2)) and demonstrate that both complexes can interact with DNA through intercalation, electrostatic attraction, or hydrogen bonding. Conclusions: The cytotoxicity profiles of the compounds were evaluated in human melanoma cell lines (SK-MEL-147, CHL-1, and WM1366), revealing greater cytotoxic activity for (1) on the CHL-1 cell line with an IC₅₀ of 14.50 ± 1.09 µM. Subsequent studies showed that (1) inhibits the proliferation of CHL-1 cells and induces apoptosis, associated at least in part with the pro-oxidant effect and cell cycle arrest at the G1/S transition. Full article