Tris Pentafluorophenyl Borane Research Articles

Multifunctional Additive Enables a "5H" PEO Solid Electrolyte for High-Performance Lithium Metal Batteries.

The solid-state battery with a lithium metal anode is a promising candidate for next-generation batteries with improved energy density and safety. However, the current polymer electrolytes still cannot fulfill the demands of solid-state batteries. In this work, we propose a "5H" poly(ethylene oxide) (PEO) electrolyte via introducing a multifunctional additive of tris(pentafluorophenyl)borane (TPFPB) for high-performance lithium metal batteries. The addition of TPFPB improves the ionic conductivity from 6.08 × 10-5 to 1.54 × 10-4 S cm-1 via reducing the crystallinity of the PEO electrolyte and enhances the lithium-ion transference number from 0.19 to 0.53 via anion trapping due to its Lewis acid nature. Furthermore, the fluorine and boron segments from TPFPB can optimize the composition of the solid-electrolyte interphase and cathode-electrolyte interphase, providing a high electrochemical stability window over 4.6 V of the PEO electrolyte along with significantly improved interface stability. At last, TPFPB can ensure improved safety through a self-extinguishing effect. As a result, the "5H" electrolyte enables the Li/Li symmetric cells to achieve a stable cycle over 2200 h at the current density of 0.2 mA cm-2 with a capacity of 0.2 mA h cm-2; the LiFePO4/Li full cells with a high LFP loading of 8 mg cm-2 exhibits decay-free capacity of 140 mA h g-1 (99% capacity retention) after 100 cycles; and the NCM811/Li cells exhibit a high capacity of 160 mA h g-1 after 50 cycles at 0.5 C. This work presents an innovative approach to utilizing a "5H" electrolyte for high-performance solid-state lithium batteries.

Tris(pentafluorophenyl)borane-catalyzed Hydride Transfer Reactions in Polysiloxane Chemistry-Piers-Rubinsztajn Reaction and Related Processes.

Tris(pentafluorophenyl)borane (TPFPB) is a unique Lewis acid that catalyzes the condensation between hydrosilanes (Si-H) and alkoxysilanes (Si-OR), leading to the formation of siloxane bonds (Si-OSi) with the release of hydrocarbon (R-H) as a byproduct-the so-called Piers-Rubinsztajn reaction. The analogous reactions of hydrosilanes with silanols (Si-OH), alcohols (R-OH), ethers (R-OR') or water in the presence of TPFPB leads to the formation of a siloxane bond, alkoxysilane (Si-OR or Si-OR') or silanol (Si-OH), respectively. The above processes, often referred to as Piers-Rubinsztajn reactions, provide new synthetic tools for the controlled synthesis of siloxane materials under mild conditions with high yields. The common feature of these reactions is the TPFPB-mediated hydride transfer from silicon to carbon or hydrogen. This review presents a summary of 20 years of research efforts related to this field, with a focus on new synthetic methodologies leading to numerous previously difficult to synthesize well-defined siloxane oligomers, polymers and copolymers of a complex structure and potential applications of these new materials. In addition, the mechanistic aspects of the recently discovered reactions involving hydride transfer from silicon to silicon are discussed in more detail.

Effect of Hole Transport Materials and Their Dopants on the Stability and Recoverability of Perovskite Solar Cells on Very Thin Substrates after 7 MeV Proton Irradiation

AbstractThe drastic reduction in launch and manufacturing costs of space hardware has facilitated the emergence of "commercial" space. Radiation‐hard organometal halide perovskite solar cells (PSCs) with low‐cost and high‐efficiency potentials are promising for space applications.High‐efficiency PSCs are tested with different hole transport materials (HTMs) and dopants on 175µm sapphire substrates under 7MeV‐proton‐irradiation‐tests at accumulated fluences of 1011, 1012, and 1013 protons cm−2. While all cells retain >90% of their initial power conversion efficiencies (PCEs) after 1011 protons cm−2 irradiation, PSCs that have tris(pentafluorophenyl)borane (TPFB) as the HTM dopant and poly[bis(4‐phenyl)(2,5,6‐trimethylphenyl) amine (PTAA) or PTAA:C8BTBT (C8BTBT = 2,7‐Dioctyl[1]benzothieno[3,2‐b][1]benzothiophene) as the HTM are more tolerant to higher‐fluence radiation than their counterparts with the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant and the 2,2′,7,7′‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD) HTM. Radiation induces fluorine diffusion from the LiTFSI dopant toward the perovskite absorber (confirmed by depth‐resolved X‐ray photoelectron spectroscopy) introducing defects. Radiation‐induced defects in cells with the TPFB dopant instead are different and can be “annealed out” by thermal vacuum resulting in PCE recovery. This is the first report using thermal admittance spectroscopy and deep‐level transient spectroscopy for defect analyses on proton‐irradiated and thermal‐vacuum‐recovered PSCs. The insights generated are expected to contribute to efforts in developing low‐cost light‐weight solar cells for space applications.

Anion Receptor Weakens ClO4− Solvation for High‐Temperature Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) with wide operating temperature are regarded as promising candidates for large‐scale energy storage systems. However, SIBs operating under elevated temperature aggravate the electrolyte decomposition with unstable cathode‐electrolyte interphase (CEI), causing a rapid capacity degradation. Herein, anion receptor tris(pentafluorophenyl)borane (TPFPB) is selected as electrolyte additive to construct robust NaF‐rich CEI. The strong interactions between anion and TPFPB via the electron‐deficient boron atoms weaken ClO4− solvation and promote the coordination capability between solvents and Na+ cations, demonstrating greatly improved oxidative stability. Na3V2(PO4)3 cathode in TPFPB‐containing electrolyte delivers long‐term stability with a capacity retention of 86.9% after 100 cycles at a high cut‐off voltage of 4.2 V (vs. Na+/Na) and a high temperature of 60 °C. Besides, TPFPB also works well with enhanced performance over a temperature range from −30 to 60 °C. This study proposes a prospective method by manipulating the solvation chemistry for constructing high‐temperature rechargeable SIBs.

Stable Anion‐Derived Solid Electrolyte Interphase in Lithium Metal Batteries

AbstractHigh‐energy‐density lithium (Li) metal batteries are severely hindered by the dendritic Li deposition dictated by non‐uniform solid electrolyte interphase (SEI). Despite its unique advantages in improving the uniformity of Li deposition, the current anion‐derived SEI is unsatisfactory under practical conditions. Herein regulating the electrolyte structure of anions by anion receptors was proposed to construct stable anion‐derived SEI. Tris(pentafluorophenyl)borane (TPFPB) anion acceptors with electron‐deficient boron atoms interact with bis(fluorosulfonyl)imide anions (FSI−) and decrease the reduction stability of FSI−. Furthermore, the type of aggregate cluster of FSI− in electrolyte changes, FSI− interacting with more Li ions in the presence of TPFPB. Therefore, the decomposition of FSI− to form Li2S is promoted, improving the stability of anion‐derived SEI. In working Li | LiNi0.5Co0.2Mn0.3O2 batteries under practical conditions, the anion‐derived SEI with TPFPB undergoes 194 cycles compared with 98 cycles of routine anion‐derived SEI. This work inspires a fresh ground to construct stable anion‐derived SEI by manipulating the electrolyte structure of anions.

Stable Anion‐Derived Solid Electrolyte Interphase in Lithium Metal Batteries

AbstractHigh‐energy‐density lithium (Li) metal batteries are severely hindered by the dendritic Li deposition dictated by non‐uniform solid electrolyte interphase (SEI). Despite its unique advantages in improving the uniformity of Li deposition, the current anion‐derived SEI is unsatisfactory under practical conditions. Herein regulating the electrolyte structure of anions by anion receptors was proposed to construct stable anion‐derived SEI. Tris(pentafluorophenyl)borane (TPFPB) anion acceptors with electron‐deficient boron atoms interact with bis(fluorosulfonyl)imide anions (FSI−) and decrease the reduction stability of FSI−. Furthermore, the type of aggregate cluster of FSI− in electrolyte changes, FSI− interacting with more Li ions in the presence of TPFPB. Therefore, the decomposition of FSI− to form Li2S is promoted, improving the stability of anion‐derived SEI. In working Li | LiNi0.5Co0.2Mn0.3O2 batteries under practical conditions, the anion‐derived SEI with TPFPB undergoes 194 cycles compared with 98 cycles of routine anion‐derived SEI. This work inspires a fresh ground to construct stable anion‐derived SEI by manipulating the electrolyte structure of anions.

Tris(pentafluorophenyl)borane‐Modified P3CT‐K as an Efficient Hole‐Transport Layer for Inverted Planar MAPbI3 Perovskite Solar Cells

AbstractPolythiophene‐acid‐based conjugated polyelectrolytes have shown great potential as hole‐transport materials for the fabrication of inverted planar perovskite devices with decent power conversion efficiencies (PCEs), benefiting from their tunable structure and functional properties. In contrast to the current progress mainly from side functional group modification, here a simple and effective strategy is reported to effectively regulate the aggregation of P3CT‐K through the modification of the thiophene units in the main chain. A small molecule tris(pentafluorophenyl)borane (TPB) is applied as the Lewis acid to interact with the thiophene unit of polythiophene chain and regulate the aggregation of conjugated polyelectrolytes. The control of aggregation of P3CT‐K not only elevates the hole mobility of P3CT‐K, but also suppresses charge recombination in P3CT‐K composite films. Consequently, the high efficiency of inverted MAPbI3 perovskite solar cells is achieved with a peak power conversion efficiency of 20.7% and simultaneously improved short‐circuit current density and fill factor. This work provides an effective method for the aggregation control of the polyelectrolyte hole materials to promote the performance of inverted planar perovskite solar cells.

Luminescent Polymorphic Co-crystals: A Promising Way to the Diversity of Molecular Assembly, Fluorescence Polarization, and Optical Waveguide.

The design of molecular optoelectronic materials based on fabricating polymorphs and/or co-crystals has received much recent attention in the fields of luminescence, sensors, nonlinear optics, and so on. If the advantages of the two crystal engineering strategies above were combined, the diversity of self-assembly fashions and the tuning of photofunctional performances would be largely extended. However, such multicomponent examples have still been very limited to date. Herein, we report the construction of luminescent polymorphic co-crystals by assembly of tris(pentafluorophenyl)borane (TPFB) with 9,10-dicyanoanthracene (DCA) and acridine (AC) as paradigms. Different stacking modes and arrangement styles based on identical building block units in polymorphic co-crystals result in adjustable crystalline morphologies and variant photophysical properties (such as fluorescence wavelength, lifetimes, and up-conversion luminescence). The optimized photoluminescence quantum yield (63.1%) and lifetime (57.1 ns) are much higher than those of the pristine assembled units. In addition, two polymorphic co-crystals (DCA@TPFB-1 and AC@TPFB-2) present prominent fluorescence polarization and optical waveguide behaviors due to the highly regulated molecular orientation. Their high one-dimensional luminescence anisotropy (0.652) and low optical waveguide loss (0.0079 dB/μm) outperform most state-of-the-art low-dimensional molecular systems and thus endow them with great opportunities for photonic materials and devices. Therefore, this work not only confirms that constructing polymorphic co-crystals can be an effective way to design new photofunctional materials for luminescence and photonic applications but also discloses a deep understanding on the relationship between variant self-assembled fashions and tunable photofunctional properties of new TPFB-based molecular materials.

Lewis-Acid Doping of Triphenylamine-Based Hole Transport Materials Improves the Performance and Stability of Perovskite Solar Cells.

Highly efficient perovskite solar cells (PSCs) fabricated in the classic n-i-p configuration generally employ triphenylamine-based hole-transport layers (HTLs) such as spiro-OMeTAD, PTAA, and poly-TPD. Controllable doping of such layers has been critical to achieve increased conductivity and high device performance. To this end, LiTFSI/tBP doping and subsequent air exposure is widely utilized. However, this approach often leads to low device stability and reproducibility. Departing from this point, we introduce the Lewis acid tris(pentafluorophenyl)borane (TPFB) as an effective dopant, resulting in a significantly improved conductivity and lowered surface potential for triphenylamine-based HTLs. Here, we specifically investigated spiro-OMeTAD, which is the most widely used HTL for n-i-p devices, and revealed improved power conversion efficiency (PCE) and stability of the PSCs. Further, we demonstrated the applicability of TPFB doping to other triphenylamine-based HTLs. Spectroscopic characterizations reveal that TPFB doping results in significantly improved charge transport and reduced recombination losses. Importantly, the TPFB-doped perovskite devices retained near 85% of the initial PCE after 1000 h of storage in the air, while the conventional LiTFSI-doped device dropped to 75%. Finally, we give insight into utilizing other similar molecular dopants such as fluorine-free triphenylborane and phosphorus-centered tris(pentafluorophenyl)phosphine (TPFP) by density functional theory analysis underscoring the significance of the central boron atom and fluorination in TPFB for the formation of Lewis acid-base adducts.

Activation of Water at the Active‐Site Cavity of Zinc Phthalocyanine with Tris(pentafluorophenyl)borane

Activation of water bound with Zn2+ has attracted much attention as an artificial model of natural enzymes. Despite many attempts, water activation accompanied with a change in the coordination geometry of Zn2+ in complexes remains a challenge. In this study, we discover a new structure that is composed of partially protonated zinc phthalocyanine (ZnPc), hydroxide ion, and tris(pentafluorophenyl)borane (TPFB). The coordination of TPFB with water bounded with ZnPc results in the dissociation of water, and the dissociated proton from water moves to one nitrogen atom of the phthalocyanine ring through the intramolecular proton transfer. On the basis of this reaction, the coordination geometry transforms from a five‐coordinated to a distorted tetrahedral species. The Zn2+‐bound hydroxide nucleophile in the ZnPc‐TPFB complex attacks amide of ε‐caprolactam to produce hydrolyzed 6‐aminohexanoic acid in toluene.

Tailoring C60 for Efficient Inorganic CsPbI2 Br Perovskite Solar Cells and Modules.

Although inorganic perovskite solar cells (PSCs) are promising in thermal stability, their large open-circuit voltage (VOC ) deficit and difficulty in large-area preparation still limit their development toward commercialization. The present work tailors C60 via a codoping strategy to construct an efficient electron-transporting layer (ETL), leading to a significant improvement in VOC of the inverted inorganic CsPbI2 Br PSC. Specifically, tris(pentafluorophenyl)borane (TPFPB) is introduced as a dopant to lower the lowest unoccupied molecular orbital (LUMO) level of the C60 layer by forming a Lewis acidic adduct. The enlarged free energy difference provides a favorable enhancement in electron injection and thereby reduces charge recombination. Subsequently, a nonhygroscopic lithium salt (LiClO4 ) is added to increase electron mobility and conductivity of the film, leading to a reduction in the device hysteresis and facilitating the fabrication of a large-area device. Finally, the as-optimized inorganic CsPbI2 Br PSCs gain a champion power conversion efficiency (PCE) of 15.19%, with a stabilized power output (SPO) of 14.21% (0.09 cm2 ). More importantly, this work also demonstrates a record PCE of 14.44% for large-area inorganic CsPbI2 Br PSCs (1.0 cm2 ) and reports the first inorganic perovskite solar module with the excellent efficiency exceeding 12% (10.92 cm2 ) by a self-developed quasi-curved heating method.

Selective Ammonia-Sensing Platforms Based on a Solution-Processed Film of Poly(3-Hexylthiophene) and p-Doping Tris(Pentafluorophenyl)Borane.

Here, we fabricate ammonia sensors based on organic transistors by using poly(3-hexylthiophene) (P3HT) blended with tris(pentafluorophenyl)borane (TPFB) as an active layer. As TPFB is an efficient p-type dopant for P3HT, the current level of the blend films can be easily modulated by controlling the blend ratio. The devices exhibit significantly increased on-state and off-state current levels owing to the ohmic current originated from the large number of charge carriers when the active polymer layer contains TPFB with concentrations up to 20 wt % (P3HT:TPFB = 8:2). The current is decreased at 40 wt % of TPFB (P3HT:TPFB = 6:4). The P3HT:TPFB blend with a weight ratio of 9:1 exhibits the highest sensing performances for various concentrations of ammonia. The device exhibits an increased percentage current response compared to that of a pristine P3HT device. The current response of the P3HT:TPFB (9:1) device at 100 ppm of ammonia is as high as 65.8%, 3.2 times that of the pristine P3HT (20.3%). Furthermore, the sensor based on the blend exhibits a remarkable selectivity to ammonia with respect to acetone, methanol, and dichloromethane, owing to the strong interaction between the Lewis acid (TPFB) and Lewis base (ammonia).

Tandem deoxygenative hydrosilation of carbon dioxide with a cationic scandium hydridoborate and B(C6F5)3.

A scandium hydridoborate complex supported by the dianionic pentadentate ligand B2Pz4Py is prepared via hydride abstraction from the previously reported scandium hydride complex with tris-pentafluorophenyl borane. Exposure of [(B2Pz4Py)Sc][HB(C6F5)3] to CO2 immediately forms [(B2Pz4Py)Sc][HCOOB(C6F5)3] at room temperature. The formatoborate complex can also be synthesized directly from the starting material (B2Pz4Py)ScCl with Et3SiH and B(C6F5)3 while in the presence of an atmosphere of CO2 in 81% yield. This compound was evaluated as the transition metal component of a tandem deoxgenative CO2 hydrosilation catalyst. At 5% loadings, complete consumption of Et3SiH was observed along with CO2 reduction products, but conversion to an inactive scandium complex identified as (B2Pz4Py)ScOSiEt3 was observed.

Tris(pentafluorophenyl)borane‐pyrrolo[3,2‐b]pyrrole Hybrids: Solid‐State Structure and Crystallization‐Induced Enhanced Emission

AbstractThe work demonstrates that the quadrupolar nature of acceptor‐donor‐acceptor pyrrolo[3,2‐b]pyrrole systems can be substantially modified via the formation of boron‐nitrogen (B−N) bonds between peripheral CN groups and B(C6F5)3. This coordination enables a strong bathochromic shift of emission for both the solid crystalline state as well as in certain solvents. The B−N complex, or co‐crystal, was effectively isolated from the reaction between a pyrrolo[3,2‐b]pyrrole with two cyanophenyl moieties and tris(pentafluorophenyl)borane (TPFB), which were mixed in non‐polar solvents or prepared via liquid‐assisted solid‐state synthesis in a ball mill. An investigation of the structure‐property relationship confirmed that the intermolecular B−N bond influences the bathochromic shift in the absorption and emission spectra and that crystallization‐induced emission enhancement was observed owing to the benefits of the molecular packing style and the intermolecular C−H⋅⋅⋅F interactions. The postsynthetic strategy involves hybridization of molecules on a molecular level, which should provide a variety of novel photofunctional materials.

The Effect of Lifsi Salt Concentration and Electrolyte Additives on the Performance of Silicon Anodes for Li-Ion Batteries

Silicon is considered a promising anode material for Li-ion batteries due to the very high theoretical capacity (ca 3600 mAh/g). In fact, commercial batteries today might have up to 5-10 wt% silicon added to the anode. The extensive expansion of the material is a challenge for the mechanical integrity of the electrode, and leads to continuous exposure of fresh surface of silicon to the electrolyte and thereby continuous formation of solid electrolyte interphase (SEI). Thus, the choice of electrolyte, i.e. an electrolyte with good passivating properties, is crucial for the performance of the anode. Common additives for electrolytes to be used in combination with silicon anodes, are fluoroethylene carbonate (FEC) and vinylene carbonate (VC), both known to reduce prior to the solvent (i.e. ethylene carbonate). Furthermore, replacing the lithium hexafluorophosphate (LiPF6) salt, known to decompose to PF5, which again form HF upon reaction with trace amounts of H2O, could improve the performance. More stable salts are particularly advantageous for silicon electrodes, as HF might attack the native surface oxide (SiO2) [1]. Salts known to be more stable are lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI), and silicon anodes have been shown to perform better with electrolytes containing LiFSI [2]. These salts are furthermore highly soluble in a wide number of solvents, and have therefore frequently been applied in concentrated electrolytes, which are showing great promise as Li-ion battery electrolytes [3]. In spite of increased viscosity and reduced conductivity, a significant change of interfacial reactions at high concentrations might outweigh these drawbacks. Improved performance of Silicon electrodes (nanowires) in highly concentrated electrolytes has been demonstrated [4]. In this work, the electrolyte was optimized by increasing the concentration of LiFSI salt (1M, 3M and 5 M), combined with the electrolyte additives FEC, as well as the anion receptors tris(hexafluoroisopropyl) (THFIPB) and tris(pentafluorophenyl) borane (TPFPB). The silicon based anodes were made of 73 wt% Si (Silgrain®, e-Si 400, a commercially available battery grade silicon from Elkem), with an average particle size of 3 µm, 11 wt% carbon black (Timcal, C-Nergy C65, CB) and 16 wt% Na-CMC binder (Sigma Aldrich Mw ~90000). Slurries were cast onto dendritic copper foil. The electrodes were cycled in 2016 coin cells in a half cell configuration with metallic lithium as the counter electrode. The impact of the concentration on the solvation of the salt was investigated by FTIR. The surface of the cycled electrodes was investigated post mortem by FTIR, XPS and SEM/EDX as well as FIB-SEM. By increasing the electrolyte concentration, the initial capacity increased, and the SEI layers were found to contain more salt reduction products, and also the SEI appeared to be thinner than for 1M concentration. However, the capacity of the 5M was fading more rapidly than the other electrolytes. The best capacity over 200 cycles was obtained for cells cycled with 3M LiFSI in combination with 10 wt% FEC and 2 wt% THFIPB. Based on the post mortem investigations, the SEI layer of this electrode was found to be rich in LiF, and with only small amounts of salt reduction products, comparable to the 1M electrolyte. [1] B. Philippe, R. Dedryvere, M. Gorgoi, H. Rensmo, D. Gonbeau, and K. Edström, Chemistry of Materials, 25(3) (2013) 394 [2] B. Philippe, R. Dedryvere, M. Gorgoi, H. Rensmo, D. Gonbeau and K. Edström, Journal of the American Chemical Society, 135 (2013) 9829 [3] Y. Yamada and A. Yamada, Journal of the Electrochemical Society, 162 (14) (2015) A2406 [4] Z. Chang, J. Wang, Z. Wu, M. Gao, S. Wu and S. Lu, Chem Sus Chem, 11 (2018) 1787

New Insights into Mechanism of Molybdenum(VI)-Dioxo Complex Catalyzed Hydrosilylation of Carbonyls: An Alternative Model for Activating Si-H Bond.

Recently, a series of oxo/nitrido-Re(V)/Mo(VI)/Ru(VI)/Mn(V) complexes were demonstrated to be efficient catalysts in activating silanes and catalyzing hydrosilylations of unsaturated organic substrates. In the present study, the high-valent molybdenum(VI)-dioxo complex MoO2Cl2 catalyzed hydrosilylations of carbonyls was reinvestigated using density functional theory method. Previous experimental and theoretical investigations suggested a [2 + 2] addition pathway for MoO2Cl2 catalyzed hydrosilylations of ketones. In the present study, we propose an ionic outer-sphere mechanistic pathway to be the most favorable pathway. The key step in the ionic outer-sphere pathway is oxygen atom of C═O bonds nucleophilically attacking the silicon atom in an η(1)-silane molybdenum adduct. The Si-H bond is then cleaved heterolytically. This process features a novel SN2@Si transition state, which then generates a loosely bound ion pair: anionic molybdenum hydride paired with silylcarbenium ion ([MoO2Cl2H](-) [SiR3(OCR'R″)](+)) in solvent. The last step is silylcarbenium ion abstracting the hydride on molybdenum hydride to yield silyl ether. The calculated activation free energy barrier of the rate-determing step was 24.1 kcal/mol for diphenylketone (PhC═OPh) and silane of PhMe2SiH. Furthermore, the ionic outer-sphere pathway is calculated to be ∼10.0 kcal/mol lower than the previously proposed [2 + 2] addition pathway for a variety of silanes and aldehyde/ketone substrates. This preference arises from stronger electrophilicity of the high-valent molybdenum(VI) metal center toward a hydride. Here, we emphasize MoO2Cl2 behaves similar to Lewis acidic trispentafluorophenyl borane B(C6F5)3 in activating Si-H bond.

Electrical Conductivity, Viscosity and Thermal Properties of TEGDME-Based Composite Electrolytes for Lithium-Air Batteries

Some important properties of the electrolytes used in Li-air batteries were investigated. Electrolyte composed of a solution of 1 M LiPF6 in tetra ethylene glycol dimethyl ether (TEGDME) was reinforced with SiO2, Al2O3, poly(ethylene) oxide (PEO) and tris (pentafluorophenyl) borane (TPFPB) additives. The eects of these reinforcements on conductivity, viscosity and thermal stability were investigated. Electrical conductivity tests were carried out using a multiparameter meter. Viscosity tests were performed in a viscometer using tuning-fork vibration method. Thermal stability of the electrolytes was tested by both TG and DSC. DOI: 10.12693/APhysPolA.129.816 PACS/topics: 88.80.F‐, 88.80., 82.45.Gj, 82.45.Wx, 81.07.‐b

Improvement of Cycling Performance of FeF3-Based Lithium-Ion Battery by Boron-Based Additives

Two boron-based additives, tris(pentafluorophenyl)borane (TPFPB) and tris(1H,1H-heptafluorobutyl)borate (THFBuBO), are studied for their effects on the cycling performance of the FeF3/Li battery. When dissolved in the electrolyte consisting of LiPF6-ethylene carbonate/1,2-dimethyl carbonate, these compounds act as F− receptors to improve the electrochemical properties of the FeF3 cathode and cycling performance. The initial discharge capacity and voltage profile of FeF3/Li battery displayed little change with the additives. However, TPFPB and THFBuBO improved the capacity retention, with respective retention rates of 85.2% and 86.5% at the 10th cycle, while this value was 68.6% when no additive was used. Inductively coupled plasma atomic emission spectroscopy analysis showed that LiF was dissociated by TPFPB or THFBuBO in the electrolyte, and its solubility was higher with TPFPB. THFBuBO has the weak affinity for F− ions to allow reversible formation/dissociation of the [THFBuBO-F]− complex. Therefore, THFBuBO maintained the capacity of the FeF3/Li battery better than TPFPB.

Electrochemical properties of LiCoPO4-thin film electrodes in LiF-based electrolyte solution with anion receptors

Compatibility of LiF + anion receptors/propylene carbonate (PC) electrolyte solution with high potential positive electrode for lithium-ion batteries was examined by cyclic voltammetry. As anion receptors, tripropyl borate (TPB), tris(pentafluorophenyl) borane (TPFPB), and tris(hexafluoroisopropyl) borate (THFIPB) were used. LiCoPO4 thin-film electrodes were prepared by sol–gel method and used as both carbon- and binder-free model electrodes. From cyclic voltammograms, LiCoPO4 showed better cycleability in 0.1 mol dm−3 LiF + 0.1 mol dm−3 THFIPB/PC, however, other anion receptors did not give positive influence. It is indicated that the surface protecting layer from F−-THFIPB complex and made LiCoPO4 stable. Electrochemical behavior depending on anion receptors was discussed according to reaction activity of F−.

Multicomponent Molecular Puzzles for Photofunction Design: Emission Color Variation in Lewis Acid-Base Pair Crystals Coupled with Guest-to-Host Charge Transfer Excitation.

Simple yet ubiquitous multimolecular assembly systems with color-tunable emissions are realized by cooperative electron donor-acceptor interactions, such as the boron-nitrogen (B-N) dative bond as a Lewis acid-base pair and charge transfer (CT) interactions. These are ternary-component systems consisting of a naphthalenediimide derivative (NDI), tris(pentafluorophenyl)borane (TPFB), and aromatic molecules (guest) with an NDI:TPFB:guest ratio of 1:2:2. The crystal shows guest-dependent color-tunable emissions such as deep blue to orange when a guest molecule of benzene is replaced with other π-conjugated systems. A good correlation between the emission wavelength and ionization potential of the guest and electronic structure calculations indicated that the emission is due to the CT transition from the guest to the NDI. The present study suggests that a rational solution of multcomponent molecular puzzles would be useful for obtaining novel photofunctional solid-state systems.