Optimization of Electrode and Cell Design for Ultrafast-Charging Lithium-Ion Batteries Based on Molybdenum Niobium Oxide Anodes.

Niobium oxides are an emerging class of anode materials for use in high-power lithium-ion batteries. Galvanostatic cycling and electrochemical impedance spectroscopy (EIS) were used in this study to investigate the influence of electrode porosity, electrode mass ratio, and cycling rate on the capacity, cycle life, and ionic conductivity of Li-ion battery cells based on a modified micron-sized MoNb12O33 (MNO) anode powder. Both electrode and cell designs were found to have a significant impact on the rate performance and cycle life of Li-ion half- and full cells. A higher specific capacity, improved rate performance, and a longer cycle life were obtained in both anode and cathode half-cells by lowering the electrode porosity through calendaring. MNO/Li half-coin cells displayed excellent cyclability, reaching 80% state of health (SOH) after 600 cycles at C/2 charge and 1C discharge. MNO/NMC622 full-coin cells displayed a high capacity of 179 mAh g-1 at 100 mA g-1 (0.5 mA cm-2) and excellent cyclability at 25 °C, reaching 70% SOH after over 1000 cycles at 1 mA cm-2 after optimizing their N/P ratio. Excellent cyclability was obtained at both 1C/1C and fast 2C/2C cycling, reaching 80% SOH after 700 and 470 cycles, respectively. Full-coin and small pouch cells had outstanding rate performance as they could be charged from 0 to 84% capacity in less than 5 min at 10 mA cm-2 and to 70% SOC in 120 s at 20 mA cm-2.

Continuous-Flow Synthesis of Carbon-Coated Silicon/Iron Silicide Secondary Particles for Li-Ion Batteries.

The development of better Li-ion battery (LIB) electrodes requires an orchestrated effort to improve the active materials as well as the electron and ion transport in the electrode. In this paper, iron silicide is studied as an anode material for LIBs because of its higher conductivity and lower volume expansion compared to pure Si particles. In addition, carbon nanotubes (CNTs) can be synthesized from the surface of iron-silicides using a continuous flow coating process where precursors are first spray dried into micrometer-scale secondary particles and are then flown through a chemical vapor deposition (CVD) reactor. Some CNTs are formed inside the secondary particles, which are important for short-range electrical transport and good utilization of the active material. Surface-bound CNTs on the secondary particles may help establish a long-range conductivity. We also observed that these spherical secondary particles allow for better electrode coating quality, cyclability, and rate performance than unstructured materials with the same composition. The developed electrodes retain a gravimetric capacity of 1150 mAh/g over 300 cycles at 1A/g as well as a 43% capacity retention at a rate of 5 C. Further, blended electrodes with graphite delivered a 539 mAh/g with high electrode density (∼1.6 g/cm3) and areal capacity (∼3.5 mAh/cm2) with stable cycling performance.

Aqueous interfacial gels assembled from small molecule supramolecular polymers.

The self-assembly of a stimuli-responsive aqueous supramolecular hyperbranched polymer from small molecules is reported. This system is composed of ditopic and tritopic guest-functionalised molecules that are able to form heteroternary supramolecular complexes with the macrocyclic host cucurbit[8]uril (CB[8]). We demonstrate that the supramolecular hyperbranched polymer formed is responsive to both photo- and chemical stimuli, exhibiting reversibility. Furthermore, this system is shown to assemble at liquid-liquid interfaces, which upon gelation, is observable on the micrometre scale. This self-healing supramolecular network can act as a soft matter barrier for aqueous microdroplets, inhibiting their coalescence.

Microcapsule Buckling Triggered by Compression-Induced Interfacial Phase Change.

There is an emerging trend toward the fabrication of microcapsules at liquid interfaces. In order to control the parameters of such capsules, the interfacial processes governing their formation must be understood. Here, poly(vinyl alcohol) films are assembled at the interface of water-in-oil microfluidic droplets. The polymer is cross-linked using cucurbit[8]uril ternary supramolecular complexes. It is shown that compression-induced phase change causes the onset of buckling in the interfacial film. On evaporative compression, the interfacial film both increases in density and thickens, until it reaches a critical density and a phase change occurs. We show that this increase in density can be simply related to the film Poisson ratio and area compression. This description captures fundamentals of many compressive interfacial phase changes and can also explain the observation of a fixed thickness-to-radius ratio at buckling, [Formula: see text].

Time-resolved ICP-MS measurement: a new method for elemental and multiparametric analysis of single cells.

Time-resolved inductively coupled plasma mass spectrometry (ICP-MS) has attracted much attention for elemental and multiparametric analysis of single cells, instead of a classical bulk analysis of large amount of cells after a dissolution. In the time-resolved measurement, cells are directly introduced into the plasma via nebulizing or micro drop dispensing, and then ion plumes corresponding to single cells are individually detected with a high time resolution. The sensitivity and cell throughput in the measurement strongly depend on the time resolution. A high cell introduction efficiency into the plasma supports for a reduction of cell consumption. Biomolecules can also be measured through the attachment of elemental tags, and then the amount distribution of elements and biomolecules in single cells can be evaluated, while providing information concerning cell-to-cell variations. By applying ICP time-of-flight mass spectrometry (ICP-TOFMS), multiparametric analysis of elements and biomolecules can be achieved similar to that by a flow cytometer. This article highlights the technical aspects of the time-resolved ICP-MS measurement technique for elemental and multiparametric analysis of single cells.

Separation and quantification of RNA molecules using size-exclusion chromatography hyphenated with inductively coupled plasma-mass spectrometry.

The hyphenation of SEC with ICP-MS was successfully applied to RNA quantification. The developed method combines the separation technique for large biomolecules and element selective detection of ICP-MS. The separation of RNA molecules was performed under the SEC condition without additive reagents such as salts to prevent the adhesion of RNA molecules on the column resin. Fragments of RNA, which were commercially available as a ladder marker solution and certified reference materials, were successfully separated and analyzed by measuring ³¹P⁺ with this method. RNA was quantified with good repeatability (RSD of peak area; 2.7%, n = 3) and linearity (R² = 0.999) using a P standard solution as a calibrant. LOD and absolute detection limit of RNA were 6.7 µg/kg and 67 pg, respectively, which were equal to the values obtained by the analysis of a P standard solution. The accuracy of the proposed measurement was evaluated by measuring certified reference materials of RNA solutions for quantitative analysis (NMIJ CRM 6204-a). The results obtained by this method agreed with the certified values within uncertainty. The proposed analysis method, which demonstrates good accuracy and high precision and is free from interference by nucleotide analogues, qualifies as a method of quality control for the RNA synthesis and extraction process.

High sensitive elemental analysis of single yeast cells (Saccharomyces cerevisiae) by time-resolved inductively-coupled plasma mass spectrometry using a high efficiency cell introduction system.

Trace elemental analysis of single yeast cells with time-resolved inductively coupled plasma mass spectrometry (ICP-MS) was successfully carried out, where a high efficiency cell introduction system (HECIS) consisting of the high performance concentric nebulizer (HPCN) and a low-volume (15 mL) on-axis spray chamber utilizing a sheath gas flow were used. Cell adsorption to the flow injector and sample tubing was reduced with the addition of a simple 4.3 mmol L(-1) of NaCl solution to the cell suspension and cell flowing liquid, allowing consecutive measurements without fear of significant contamination from previous measurements. Initially using a quadrupole mass analyzer ICP-MS (ICP-QMS) at its lowest integration time (10 ms), current spikes corresponding to separate cell events were detected for several elements (Mg, P, Ca, Mn, Fe, Cu, and Zn) on the introduction of the cell suspension. On comparing the number of peaks in the spectrum for phosphorous with the cell count using a haemocytometer, a reproducible cell transport efficiency of 75.0 ± 4.7% was achieved. Preliminary experiments into using time of flight ICP-MS (ICP-TOFMS) for single-cell analysis were carried out, allowing quasi-simultaneous multielement detection. The spectra of Mg, P, Ca, Mn, Fe, Cu, and Zn, with a time resolution of 1 ms were simultaneously obtained in one measurement. A relatively strong correlation was observed for the spectra between P and Zn (correlation factor 0.69), P and Mg (0.63), and Mg and Zn (0.63). These results indicate that the time resolved quasi-simultaneous multielement measurement may be useful for the correlation analysis of multielements in cells.