Li-ion cell designs, component integrity, and manufacturing processes all have critical influence on the safety of Li-ion batteries. Any internal defective features that induce a short circuit, can trigger a thermal runaway: a cascade of reactions, leading to a device fire. As consumer device manufacturers push aggressively for increased battery energy, instances of field failure are increasingly reported. Notably, Samsung made a press release in 2017 following a total product recall of their Galaxy Note 7 mobile phone, confirming speculation that the events were attributable to the battery and its mode of manufacture. Recent incidences of battery swelling on the new iPhone 8 have been reported in the media, and the techniques and lessons reported herein may have future relevance. Here we look deeper into the key components of one of these cells and confirm evidence of cracking of electrode material in tightly folded areas, combined with a delamination of surface coating on the separator, which itself is an unusually thin monolayer. We report microstructural information about the electrodes, battery welding attributes, and thermal mapping of the battery whilst operational. The findings present a deeper insight into the battery's component microstructures than previously disseminated. This points to the most probable combination of events and highlights the impact of design features, whilst providing structural considerations most likely to have led to the reported incidences relating to this phone.

The present work deals with the effect of iron intermetallics on the microstructure and mechanical properties of Al-7% Si alloys. Two different iron additions were made, 0.6% Fe and 2% Fe, to study the effect of iron intermetallics on Al-Si alloys. Microstructure property correlations were carried out using SEM-EDS and tensile testing of alloys. Microstructure results show that the rise in iron content significantly increased the average size, thickness and number of intermetallic particles in the alloys. Nano-indentation study shows that the iron intermetallics are too brittle compared with the primary aluminium. Moreover, the hardness and Young's modulus of iron intermetallics are higher than those of primary aluminium. Tensile test results show that there is no significant difference in strength levels between Al-7%Si and Al-7Si-0.6Fe alloys. However, an increase in iron from 0.6% to 2% resulted in a significant decrease in tensile strength and elongation of the alloys. Two-dimensional SEM studies suggest that the increased number of needle-shaped b-phase intermetallic particles formed because of increased amounts of Fe could be the reason for early failure of the alloy. To further understand the early failure of iron-containing alloys, the fractured tensile specimens were studied using the 3D x-ray tomography technique. XCT results show that the failure in tensile testing of 2% Fe alloy was not mainly due to breaking of brittle b-phase intermetallic particles, but due to the morphology and particle-matrix interface debonding. XCT shows that the needleshaped particles are long, sharp-edged platelets in 3D, which act as stress raisers for crack initiation and propagation along the interphase.

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Regenerative hydrogen/vanadium flow cells (RHVFCs) require electrode architectures combining electrochemical, catalytic, and mechanical properties across nano-, micro-, and milliscales. The use of current carbon-based electrodes can lead to poor electrolyte utilization, slow kinetics, and rapid electrode deterioration, resulting in suboptimal electrochemical performance and hindering RHVFC's commercial viability.To address this, we here demonstrate the application of trichome-like carbon-metal fabrics (CMFs) made of carbon microfibers, carbon nanotubes, and iron-based nanoparticles as both a catalytic layer and electrode in RHVFCs by evaluating their key figures of merit. CMFs in combination with commercial carbon cloth not only offer a high power density ∼645 mW cm −2 (∼0.82 V) but also excellent cycling performance at 150 mA cm −2 , yielding nearly 100% energy efficiency and a high average discharge capacity of ∼23 Ah L −1 (∼90% electrolyte utilization). These electrochemical results together with electrode microstructural features assessed by X-ray tomography and projected cost analysis represent a step change in the design and development of tailored electrodes capable of withstanding RHVFC cycling conditions without compromising electrochemical performance.

6(N.K.); R.Genieser@warwick.ac.uk (R. G

lett.9b00663.Experimental section and additional results on z-plane wireless charging misalignment and temperature effect on charging current (PDF)

No abstract

Abstract. The eastern cloud of the nearby Cepheus complex, located at 111• < l < 117• and 14• , has been mapped in the CO(J = 1 → 0) transition at a resolution of 0.8 pc with the CfA 1.2 m telescope. This massive, but fairly diffuse cloud, with visual extinction < 2 mag, has also been sampled in the J = 1 → 0 and 2→1 rotational transitions of CO and 13 CO at the same resolution, using the CfA and POM-2 millimeter telescopes.The radiative transfer of the lines has been treated in the LTE and LVG approximations, the two yielding comparable results. In CO, low excitation temperatures have been found in the range of 5 − 11 K, with moderate optical depths (τ < 3) and CO column-densities up to 4 10 16 cm −2 . In 13 CO, the gas is optically thin with slightly lower excitation temperatures of 4−8 K, for 13 CO column-densities up to 6 10 15 cm −2 . Under these conditions, the observed ratios of 2 → 1 over 1 → 0 velocityintegrated intensities, W 2→1 /W 1→0 , have been found to be consistent with a uniform value over the cloud of 0.88 ± 0.09 in CO and 0.60 ± 0.07 in 13 CO, as typical of many clouds.The ratios of CO over 13 CO velocity-integrated intensities, W ( 12 CO)/W ( 13 CO), have been found to decrease with 13 CO intensity as expected from the progressive saturation of the CO lines. The large scatter about this relation, observed at scales of 0.8 and 0.2 pc, cannot be accounted for by instrumental error, beam dilution, or the dispersion of excitation temperatures and line widths measured in the cloud. The W ( 12 CO)/W ( 13 CO) fluctuations are therefore indicative of intrinsic variations in the molecular abundances. In particular, very low W ( 12 CO)/W ( 13 CO) ratios may result from efficient isotopic fractionation in this cold environment. Similar vari-