No abstract

Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries. However, the formation of dendritic and mossy Li metal microstructures at the negative electrode during stripping/plating cycles causes electrolyte decomposition and the formation of electronically disconnected Li metal particles. Here we investigate the use of a Cu current collector coated with a high dielectric BaTiO3 porous scaffold to suppress the electrical field gradients that cause morphological inhomogeneities during Li metal stripping/plating. Applying operando solid-state nuclear magnetic resonance measurements, we demonstrate that the high dielectric BaTiO3 porous scaffold promotes dense Li deposition, improves the average plating/stripping efficiency and extends the cycling life of the cell compared to both bare Cu and to a low dielectric scaffold material (i.e., Al2O3). We report electrochemical tests in full anode-free coin cells using a LiNi0.8Co0.1Mn0.1O2-based positive electrode and a LiPF6-based electrolyte to demonstrate the cycling efficiency of the BaTiO3-coated Cu electrode.

A time of flight Modulation of Intensity by Zero Effort spectrometer mode has been developed for the Larmor instrument at the ISIS pulsed neutron source. The instrument utilizes resonant neutron spin flippers which employ electromagnets with pole shoes, allowing the flippers to operate at frequencies of up to 3 MHz. Tests were conducted at modulation frequencies of 103 kHz, 413 kHz, 826 kHz and 1.03 MHz, resulting in a Fourier time range of ~0.1 ns to 30 ns using a wavelength band of 4 Å to 11 Å.

Li 3 YX 6 (X = Cl, Br) materials are Li-ion conductors that can be used as solid electrolytes in all solid-state batteries. Solid electrolytes ideally have high ionic conductivity and (electro)chemical compatibility with the electrodes. It was proven that introducing Br to Li 3 YCl 6 increases ionic conductivity but, according to thermodynamic calculations, should also reduce oxidative stability. In this paper, the trade-off between ionic conductivity and electrochemical stability in Li 3 YBr x Cl 6−x halogensubstituted compounds is investigated. The compositions of Li 3 YBr 1.5 Cl 4.5 and Li 3 YBr 4.5 Cl 1.5 are reported for the first time, along with a consistent analysis of the whole Li 3 YBr x Cl 6−x (x = 0− 6) tie-line. The results show that, while Br-rich materials are more conductive (5.36 × 10 −3 S/cm at 30 °C for x = 4.5), the oxidative stability is lower (∼3 V compared to ∼3.5 V). Small Br content (x = 1.5) does not affect oxidative stability but substantially increases ionic conductivity compared to pristine Li 3 YCl 6 (2.1 compared to 0.049 × 10 −3 S/cm at 30 °C). This work highlights that optimization of substitutions in the anion framework provide prolific and rational avenues for tailoring the properties of solid electrolytes.

The initial formation stages of surfactant-templated silica thin films which grow at the air−water interface were studied using combined spin−echo modulated small-angle neutron scattering (SEMSANS) and small-angle neutron scattering (SANS). The films are formed from either a cationic surfactant or nonionic surfactant (C 16 EO 8) in a dilute acidic solution by the addition of tetramethoxysilane. Previous work has suggested a two stage formation mechanism with mesostructured particle formation in the bulk solution driving film formation at the solution surface. From the SEMSANS data, it is possible to pinpoint accurately the time associated with the formation of large particles in solution that go on to form the film and to show their emergence is concomitant with the appearance of Bragg peaks in the SANS pattern, associated with the two-dimensional hexagonal order. The combination of SANS and SEMSANS allows a complete depiction of the steps of the synthesis that occur in the subphase.

A time of flight MIEZE spectrometer study is presented. The instrument uses solenoid radio frequency (RF) spin flippers with square pole shoes and a magnetic yoke. These flippers can achieve higher static fields than conventional resonant RF spin flippers, which employ an air core. High fields are crucial for the construction of a high resolution and compact MIEZE spectrometer. Using both types of flippers two MIEZE spectrometer configurations are constructed and compared on the same beam line. It was demonstrated that the pole shoe/solenoid coil RF flippers can achieve a MIEZE signal, which is similar in quality to the conventional reference setup. The highest obtained modulation frequency was 100 kHz.

The materials Li3YX6 (X = Cl, Br) are Li-ion conductors to be used as solid electrolytes in all solid-state batteries. Solid electrolytes ideally have high ionic conductivity and (electro)chemical compatibility with the electrodes. It was proven that introducing Br to Li3YCl6 increases ionic conductivity, but, according to thermodynamic calculations, should also reduce oxidative stability. In this paper, the trade-off between ionic conductivity and electrochemical stability in Li3YBrxCl6-x (x = 0 – 6) is investigated. The results show that, while Br-rich materials are more conductive (5.36 10-3 S/cm at 30°C for x = 4.5), the oxidative stability is lower (3V compared to 3.5V). Small Br content (x = 1.5) doesn’t affect oxidative stability but substantially increases ionic conductivity compared to pristine Li3YCl6 (2.1 compared to 0.049 10-3 S/cm at 30°C). This work highlights that optimization of substitutions in the anion-framework provide prolific and rational avenues for tailoring the properties of solid electrolytes.

The quaternary compound Cs 2 Pb(MoO 4 ) 2 was synthesized and its structure was characterized using X-ray and neutron diffraction from 298 to 773 K, while thermal expansion was studied from 298 to 723 K. The crystal structure of the high-temperature phase β-Cs 2 Pb(MoO 4 ) 2 was elucidated, and it was found to crystallize in the space group R 3̅ m (No. 166), i.e., with a palmierite structure. In addition, the oxidation state of Mo in the low-temperature phase α-Cs 2 Pb(MoO 4 ) 2 was studied using X-ray absorption near-edge structure spectroscopy. Phase diagram equilibrium measurements in the Cs 2 MoO 4 –PbMoO 4 system were performed, revisiting a previously reported phase diagram. The equilibrium phase diagram proposed here includes a different composition of the intermediate compound in this system. The obtained data can serve as relevant information for thermodynamic modeling in view of the safety assessment of next-generation lead-cooled fast reactors.