The small energy pooling rate constant for THAP indicates that the potential contribution of the energy pooling mechanism to the generation of THAP matrix primary ions should be reconsidered.

No abstract

Combining high energy density electrodes, such as silicon and NMC, has the potential to meet the growing demand of high energy electric vehicles. Herein, we report a full-cell design using a macroporous silicon anode and alumina-coated NMC cathode that provides stable cyclability by means of capacity-limited charging. The proposed Si-NMC full-cell design with alumina passivation on cathode has exhibited a stable capacity of 1000 mAh/g, with 1.2 times higher energy density than the Si-NMC full-cell without cathode passivation. The role of alumina coating on the altered half-cell electrode charging mechanisms and electrochemical full-cell reactions with Si anode was investigated systematically using various structural and chemical analyses. The alumina passivated Si-NMC full-cell designed in this study elucidated an interesting electrochemical behavior of Li trapping, which shed light on a significant pathway in the efficient utilization of Si-NMC battery for high energy applications.

The structure of organic matter in anthracite samples of different ranks and coal-derived natural graphites was investigated using XRD, micro-Raman spectroscopy, and HRTEM to determine XRD and Raman parameters that are suitable to characterize the structural evolution of anthracite throughout the coalification and natural graphitization processes. Additionally, the reactive force field molecular dynamics simulations were performed based on the molecular model of one anthracite analyzed in the present study to visualize the structural evolution of the carbon skeleton of anthracite at a molecular scale. The XRD parameters d (002)-spacing and full width at half maximum (FWHM) of (002) reflections of the short-range ordered carbon skeleton in anthracite do not show an obvious change trend with the coal rank increases before the transition stage between coalification and graphitization, which dispaly a decreasing change trend when entering the graphitization stage. This indicates the two XRD parameters may not be the reliable indicators to identify the structure of high-rank coals prior to meta-anthracite due to the fact that the microcrystalline structure of graphite has not been formed at the coalification stage, but are applicable to characterize the structural order of graphite with different graphitization degree. The Raman parameters D1-FWHM, G-FWHM, and their height and area ratios show a regular change trend for anthracite at the coalification and graphitization stages, which are effective to follow the structural evolution of high-rank coals during coalification and graphitization processes. The temperature plays an important role in facilitating the coalescence of carbon layers of anthracite and the ordered arrangement of carbon layers during coalification and graphitization processes by removing the heteroatomic cross-linkers and some hydrogen and reorienting the carbon layers. Besides the temperature, the pressure, shear stress, and time are also important factors promoting the graphitization of anthracite in nature.

RationaleUltraviolet matrix‐assisted laser desorption/ionization (MALDI) is among the most popular soft ionization methods in mass spectrometry. Several theoretical models have been proposed to explain the primary ion generation in MALDI. These models require knowledge of various matrix molecular parameters for simulation. One such parameter is the fluorescence quantum yield. However, the fluorescence quantum yield reported in previous studies remains controversial.MethodsIn this study, we used a commercial and a homemade integrating sphere to measure the absorption and fluorescence quantum yields of several commonly used matrices, including 2,3‐dihydroxybenzoic acid, 2,4‐dihydroxybenzoic acid (2,4‐DHB), 2,5‐dihydroxybenzoic acid (2,5‐DHB), 2,6‐dihydroxybenzoic acid, 3,4‐dihydroxybenzoic acid, 3,5‐dihydroxybenzoic acid, α‐cyano‐4‐hydroxycinnamic acid, 2,4,6‐trihydroxyacetophenone, and ferulic acid.ResultsThe fluorescence quantum yields of these matrices were determined to be low (<0.08) at low laser fluences and decreased as the laser fluence increased. The fluorescence quantum yields at the typical laser fluence for MALDI are below 0.04 (2,4‐DHB and 2,5‐DHB) and 0.01 (the other matrices). Shot‐to‐shot fluctuations of fluorescence intensity and absorption are not directly related to the fluctuation of ions. Possible mechanisms for the decrease in the fluorescence quantum yield as the laser fluence increased were discussed.ConclusionsThe fluorescence quantum yields of these commonly used matrices are much lower than those reported in previous studies. Although fluorescence quantum yield is an important parameter and it is crucial to obtain an accurate value for theoretical models in simulations, the use of fluorescence quantum yield alone is not a sufficient parameter to justify these models.