Harnessing Ion-Dipole Interactions for Water-Lean Solvation Chemistry: Achieving High-Stability Zn Anodes in Aqueous Zinc-Ion Batteries.

The reversibility and stability of aqueous zinc-ion batteries (AZIBs) are largely limited by water-induced interfacial parasitic reactions. Here, dimethyl(3,3-difluoro-2-oxoheptyl)phosphonate (DP) is introduced to tailor primary solvation sheath and inner-Helmholtz configurations for robust zinc anode. Informed by theoretical guidance on solvation process, DP with high permanent dipole moments can effectively substitute the coordination of H2O with charge carriers through relatively strong ion-dipolar interactions, resulting in a water-lean environment of solvated Zn2+. Thus, interfacial side reactions can be suppressed through a shielding effect. Meanwhile, lone-pair electrons of oxygen and fluorinated features of DP also reinforce the interfacial affinity of metallic zinc, associated with exclusion of neighboring water to facilitate reversible zinc planarized deposition. Thus, these merits endow the Zn anode with a high-stability performance exceeds 3800 hours at 0.5 mA cm-2 and 0.5 mAh cm-2 for Zn||Zn batteries and a high average Coulombic efficiency of 99.8 % at 4 mA cm-2 and 1 mAh cm-2 for Zn||Cu batteries. Benefiting from the stable zinc anode, the Zn||NH4V4O10 cell maintains 80.3 % of initial discharge capacity after 3000 cycles at 5 A g-1 and exhibits a high retention rate of 99.4 % against to the initial capacity during the self-discharge characterizations.

A Flexible Triboelectric Nanogenerator Based on Multilayer MXene/Cellulose Nanofibril Composite Film for Patterned Electroluminescence Display.

The flexible self-powered display system integrating a flexible triboelectric nanogenerator (TENG) and flexible alternating current electroluminescence (ACEL) has attracted increasing attention for its promising potential in human-machine interaction applications. In this work, a performance-enhanced MXene/cellulose nanofibril (CNF)/MXene-based TENG (MCM-TENG) is reported for powering a flexible patterned ACEL device in order to realize self-powered display. The MCM multilayer composite film was self-assembled through the layer-by-layer method. The MCM film concurrently acted as a triboelectric layer and electrode layer due to its high conductivity and strength. Moreover, the effect of CNF concentration and number of layers on the output performance of TENG was investigated. It was found that the MCM-TENG realized the optimum output performance. Finally, a flexible self-powered display device was realized by integrating the flexible TENG and ACEL. The MCM-TENG with an output voltage of ≈90 V at a frequency of 2 Hz was found to be efficient enough to power the ACEL device. Therefore, the as-fabricated flexible TENG demonstrates a promising potential in terms of self-powered displays and human-machine interaction.

A new model based on adiabatic flame temperature for evaluation of the upper flammable limit of alkane-air-CO2 mixtures.

For security issue of alkane used in Organic Rankine Cycle, a new model to evaluate the upper flammability limits for mixtures of alkanes, carbon dioxide and air has been proposed in present study. The linear relationship was found at upper flammability limits between molar fraction of diluent in alkane-CO2 mixture and calculated adiabatic flame temperature. The prediction ability of the variable calculated adiabatic flame temperature model that incorporated the linear relationship above is greatly better than the models that adopted the fixed calculated adiabatic flame temperature at upper flammability limit. The average relative differences between results predicted by the new model and observed values are less than 3.51% for upper flammability limit evaluation. In order to enhance persuasion of the new model, the observed values of n-butane-CO2 and isopentane-CO2 mixtures measured in this study were used to confirm the validity of the new model. The predicted results indicated that the new model possesses the capacity of practical application and can adequately provide safe non-flammable ranges for alkanes diluted with carbon dioxide.

A quantitative risk-assessment system (QR-AS) evaluating operation safety of Organic Rankine Cycle using flammable mixture working fluid.

Mixture of hydrocarbon and carbon dioxide shows excellent cycle performance in Organic Rankine Cycle (ORC) used for engine waste heat recovery, but the unavoidable leakage in practical application is a threat for safety due to its flammability. In this work, a quantitative risk assessment system (QR-AS) is established aiming at providing a general method of risk assessment for flammable working fluid leakage. The QR-AS covers three main aspects: analysis of concentration distribution based on CFD simulations, explosive risk assessment based on the TNT equivalent method and risk mitigation based on evaluation results. A typical case of propane/carbon dioxide mixture leaking from ORC is investigated to illustrate the application of QR-AS. According to the assessment results, proper ventilation speed, safe mixture ratio and location of gas-detecting devices have been proposed to guarantee the security in case of leakage. The results revealed that this presented QR-AS was reliable for the practical application and the evaluation results could provide valuable guidance for the design of mitigation measures to improve the safe performance of ORC system.

1,1'-(Butane-1,4-di-yl)dipyridinium dibromide dihydrate.

The organic cation in the title compound, C(14)H(18)N(2) (2+)·2Br(-)·2H(2)O, is situated on an inversion centre. The cations, anions and water mol-ecules are linked via O-H⋯Br, C-H⋯Br and C-H⋯O hydrogen bonds, and π-π stacking inter-actions between adjacent pyridine rings, with a centroid-centroid separation of 3.8518 (17) Å.