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Fluoride shuttle batteries (FSBs), which utilize F– ion migration in electrochemical reactions, have recently advanced in academic research as next-generation rechargeable batteries. Bismuth trifluoride (BiF₃) and its relatives are expected to be promising positive electrode materials for FSBs because of their high theoretical capacity. Herein, the defluorination/fluorination reaction of a BaF₂-doped BiF₃, Bi₀.₈Ba₀.₂F₂.₈, positive electrode was investigated using synchrotron-radiation X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. The Bi₀.₈Ba₀.₂F₂.₈ electrode showed a higher reversible capacity in the first cycle and improved capacity retention compared to the BiF₃ electrode. The pristine Bi₀.₈Ba₀.₂F₂.₈ showed a tysonite-type structure, and metallic Bi and BaF₂ nanoparticles were observed in the fully defluorinated state. Moreover, we found that the (re-)fluorinated material consisted of BiF₃ and BaF₂ nanoparticles, indicating that bismuth is the only redox-active element, and that the tysonite structure is not recovered after the initial discharging. This suggests that the cycle performance of the Bi₀.₈Ba₀.₂F₂.₈ electrode may be improved due to the suppression of the coarsening of BiF₃ nanoparticles by the adhesion of BaF₂ nanoparticles formed after initial defluorination.

Ionic mobility in solid solutions with tysonite structure obtained by doping bismuth trifluoride with potassium and neodymium fluorides is studied using 19F NMR. The types of ionic motions are determined in the fluoride sublattice of the synthesized solid solutions at 150–450 K, their activation energies are estimated.

Gananite is a rare bismuth based mineral with a general formula of bismuth trifluoride (BiF3). In this manuscript, a facile laboratory based wet-chemical method has been reported for the synthesis of organic molecule stabilized BiF3 nanoparticles for the electrochemical supercapacitor application. The X-ray diffraction pattern indicates the crystalline nature of the BiF3 nanoparticles with the pure form of the face centered cubic crystal structure. At current densities of 2 and 70 A g−1, the material exhibited specific capacitances of 1127 and 400 F g−1, respectively, in the presence of 10 wt% of carbon black as a dopant, within a potential range from −1.0 to 0.0 V. Under the above mentioned conditions the capacitor also showed superior energy and power density values (313 and 112 W h kg−1 at 1.9 and 70 kW kg−1, respectively). The BiF3 based device displays high cycling stability and retains 96% of its initial specific capacitance after 103 uninterrupted charge–discharge cycles at a current density of 10 A g−1.

The ion mobility and conductivity of solid solutions with tysonite-type structure obtained by doping bismuth trifluoride with lead (II) fluoride, and zirconium and bismuth oxides have been studied using 19F NMR, X-ray diffraction analysis, and impedance spectroscopy. The types of ionic motions in the fluoride sublattice of the synthesized solid solutions in the temperature range 150–450 K have been determined and the energy of their activation has been estimated. Due to high ionic conductivity, above 10–2 S/cm at 570 K, these solid solutions can be considered as superionic conductors.

Fluoride shuttle batteries (FSBs), which utilize F– ion migration in electrochemical reactions, have recently advanced in academic research as next-generation rechargeable batteries. Bismuth trifluoride (BiF3) and its relatives are expected to be promising positive electrode materials for FSBs because of their high theoretical capacity. Herein, the defluorination/fluorination reaction of a BaF2-doped BiF3, Bi0.8Ba0.2F2.8, positive electrode was investigated using synchrotron-radiation X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. The Bi0.8Ba0.2F2.8 electrode showed a higher reversible capacity in the first cycle and improved capacity retention compared to the BiF3 electrode. The pristine Bi0.8Ba0.2F2.8 showed a tysonite-type structure, and metallic Bi and BaF2 nanoparticles were observed in the fully defluorinated state. Moreover, we found that the (re-)fluorinated material consisted of BiF3 and BaF2 nanoparticles, indicating that bismuth is the only redox-active element, and that the tysonite structure is not recovered after the initial discharging. This suggests that the cycle performance of the Bi0.8Ba0.2F2.8 electrode may be improved due to the suppression of the coarsening of BiF3 nanoparticles by the adhesion of BaF2 nanoparticles formed after initial defluorination.

A rechargeable lithium anode requires a porous structure for a high capacity, and a stable electrode/electrolyte interface against dendrite formation and polysulfide crossover when used in a lithium-sulfur battery. Here, we design two simple steps of spontaneous reactions for protecting porous lithium electrodes. First, a reaction between molten lithium and sulfur-impregnated carbon nanofiber forms a fibrous network with a lithium shell and a carbon core. Second, we coat the surface of this porous lithium electrode with a composite of lithium bismuth alloys and lithium fluoride through another spontaneous reaction between lithium and bismuth trifluoride, solvated with phosphorous pentasulfide, which also polymerizes with lithium sulfide residual in the electrode to form a solid electrolyte layer. This protected porous lithium electrode enables stable operation of a lithium-sulfur battery with a sulfur loading of 10.2 mg cm−2 at 6.0 mA cm−2 for 200 cycles., Stabilizing lithium anodes has been a crucial yet challenging task in developing high-energy batteries. Here the authors design two simple steps of spontaneous reactions to achieve a porous lithium electrode with a composite protective layer, enabling high-loading Li-S batteries with excellent cyclability.

The glasses in the ZrF 4 –BiF 3 –BaF 2 system with different content of bismuth trifluoride have been investigated. The trends of the decrease of glass transition and crystallization temperatures along with the increase of the BiF 3 content in glass, the presence of more than one crystallization peak and composition of crystalline phases in glasses have been revealed. All the studied glasses of the fluorozirconate series have nanosized heterogeneities of virtually the same scale. The crystallization process depends on the bismuth trifluoride content in glass. The contribution of photoluminescence of bismuth with transition emission 540 nm was found for the glass doped with 1% Bi.

Bismuth Trifluoride (BiF 3 ), with a high thermal stability and a low deposition temperature, has been studied as a novel dopant for the conventional hole transporting material of N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB). The efficiency and lifetime of organic light-emitting diodes (OLEDs) have been remarkably improved by using BiF 3 doped NPB. For an optimized green device, a current efficiency of 21.6 cd/A is reached, 40% higher than the control device without BiF 3 . And the lifetime is increased from 115 h to 222 h at room temperature. The enhanced efficiency and lifetime are attributed to the improved balance of holes and electrons in the emissive layer. Most importantly, the thermal stability at an elevated temperature of the OLEDs with BiF 3 doped NPB is largely improved, showing an order of magnitude longer lifetime than the control device at 80 °C.

The electrical conductivity of oxyfluoride glasses in the MnNbOF5-BaF2-BiF3 system in the temperature range 299–550 K was studied by impedance spectroscopy. It was shown that the conductivity is mainly caused by fluoride ions forming fluorobismuth polyhedra in the glass structure, being as high as 7.46 × 10−3 S/cm (533 K) in the 20MnNbOF5-30BaF2-50BiF3 system reaches, which is at the level of the best values for fluoride glasses.

Glasses have been prepared in the InF3-BiF3-BaF2-PbF2-ZnF2-LnF3 (Ln = Eu, Tm) system. The short-range and medium-range order structure of the glass network is discussed on the basis of IR and Raman spectroscopy data. The effect of bismuth trifluoride on the thermal properties, structure, and photo-luminescence properties of glasses was studied. Bismuth trifluoride doping improves the thermal parameters of glasses. The polyhedra formed by bismuth trifluoride in the glass are not involved in the medium-range order. In rare-earth-containing glasses, strong photoluminescence was discovered in the range 530–560 nm with excitation by the Raman-masking 532-nm wavelength. Bismuth in the glass enhances the europium photoluminescence level in the glass of the InF3-BiF3-BaF2-PbF2-ZnF2-EuF3 system.

New glasses are prepared in the MnNbOF5-BaF2-BiF3 system. The thermal parameters of these glasses are analyzed as influenced by bismuth trifluoride. IR and Raman spectroscopy shows that the glass structures are built of Nb(O, F)6 polyhedra, which are linked by oxygen bridges to form glass nets via. A medium-order order region in the glass includes fluoroniobate polyhedra not linked directly to bismuth trifluoride polyhedra. A Ba0.55Bi0.45F2.45 crystalline phase is discovered at 320°C in a glass of composition 20MnNbOF5-40BaF2-40BiF3.

Glass formation in the InF3-BiF3-BaF2 system is studied. Partial substitutions of BiF3 for InF3 in the InF3-BaF2 system reduce the glass-transition and glass-crystallization temperatures and increase the thermal stability range and refractive index. The glass structure is studied using IR and Raman spectroscopy. InF6 and BiFn polyhedra are identified in the system. Doping the glass with bismuth trifluoride changes the degree and linkage character of the InF6 polyhedra in the glass network. The medium-range order length is not affected by the bismuth trifluoride concentration in the glass. The modifier cation (Ba2+) substantially determines the correlation length in the glasses.

Monodisperse orthorhombic-phase BiF(3) nanocrystals with various shapes were prepared easily by a novel solvent extraction approach using an acid-base-coupled extractant. More importantly, the extractant used in this route can be recycled after synthesis. Our results show great promise for further extending the method to the preparation of other metal-fluoride nanoparticles.

The InF3-BaF2-BiF3 glass-forming system is investigated by the IR and19F NMR spectroscopic techniques. The influence of bismuth trifluoride on the dynamic behavior of fluorine ions and the structure of glasses in this system is demonstrated.

The processes of anodic oxidation of bismuth in neutral aqueous halide solutions have been investigated. It has been found by X-ray diffraction analysis that in KCl, KBr and KI solutions, porous polycrystalline anodic bismuth oxyhalide (BiOHal) films are formed on the bismuth electrode, while in KF solutions, a bismuth trifluoride (BiF3) film with an admixture of tysonite-type BiOxF3−2x phases (0

Films of BiF(3) with thicknesses up to 2.35 microm have been deposited on KCl. Similar optical properties have been obtained in films prepared by thermal evaporation and reactive sputtering in a Freon atmosphere. A very broad transmission range from 2600 A to 20 microm has been measured on BiF(3) films ~1 microm thick. Far ir and Auger spectra are presented. BiF(3) appears promising as a new optical thin film coating for applications not involving high powers at 10.6 microm and longer wavelengths.