RESUMEN
Zinc metal suffers from violent and long-lasting water-induced side reactions and uncontrollable dendritic Zn growth, which seriously reduce the coulombic efficiency (CE) and lifespan of aqueous zinc-metal batteries (AZMBs). To suppress the corresponding harmful effects of the highly active water, a stable zirconium-based metal-organic framework with water catchers decorated inside its sub-nano channels is used to protect Zn-metal. Water catchers within narrow channels can constantly trap water molecules from the solvated Zn-ions and facilitate step-by-step desolvation/dehydration, thereby promoting the formation of an aggregative electrolyte configuration, which consequently eliminates water-induced corrosion and side reactions. More importantly, the functionalized sub-nano channels also act as ion rectifiers and promote fast but even Zn-ions transport, thereby leading to a dendrite-free Zn metal. As a result, the protected Zn metal demonstrates an unprecedented cycling stability of more than 10 000 h and an ultra-high average CE of 99.92% during 4000 cycles. More inspiringly, a practical NH4V4O10//Zn pouch-cell is fabricated and delivers a capacity of 98 mAh (under high cathode mass loading of 25.7 mg cm-2) and preserves 86.2% capacity retention after 150 cycles. This new strategy in promoting highly reversible Zn metal anodes would spur the practical utilization of AZMBs.
RESUMEN
Aqueous zinc-metal batteries (AZMBs) have received tremendous attentions due to their high safety, low cost, environmental friendliness, and simple process. However, zinc-metal still suffer from uncontrollable dendrite growth and surface parasitic reactions that reduce the Coulombic efficiency (CE) and lifetime of AZMBs. These problems which are closely related to the active water are not well-solved. Here, an ultrathin crack-free metal-organic framework (ZIF-7x -8) with rigid sub-nanopore (0.3 nm) is constructed on Zn-metal to promote the de-solvation of zinc-ions before approaching Zn-metal surface, reduce the contacting opportunity between water and Zn, and consequently eliminate water-induced corrosion and side-reactions. Due to the presence of rigid and ordered sub-nanochannels, Zn-ions deposits on Zn-metal follow a highly ordered manner, resulting in a dendrite-free Zn-metal with negligible by-products, which significantly improve the reversibility and lifespan of Zn-metals. As a result, Zn-metal protected by ultrathin crack-free ZIF-7x -8 layer exhibits excellent cycling stability (over 2200 h) and extremely-high 99.96% CE during 6000 cycles. The aqueous PANI-V2 O5 //ZIF-7x -8@Zn full-cell preserves 86% high-capacity retention even after ultra-long 2000 cycles. The practical pouch-cell can also be cycled for more than 120 cycles. It is believed that the simple strategy demonstrated in this work can accelerate the practical utilizations of AZMBs.
RESUMEN
Titanium alloy materials are used in a variety of engineering applications in the aerospace, aircraft, electronics, and shipbuilding industries, and due to the continuous improvement of the contemporary age, surface integrity needs to be improved for engineering applications. Belt grinding parameters and levels directly affect the surface integrity of titanium alloys (TC4), which further affects the fatigue life of the titanium alloys during service. In order to investigate the surface integrity of titanium alloys at different roughness levels, the surfaces were repeatedly ground with the same type and different models of abrasive belts. The results showed that at roughness Ra levels of 0.4 µm to 0.2 µm, the compressive residual stresses decreased with increasing linear velocity and there were problems with large surface morphological defects. At the roughness Ra of 0.2 µm or less, grinding improves the surface morphology, the compressive residual stress increases with increasing feed rate, and the surface hardness decreases with increasing linear velocity. In addition, the research facilitates the engineering of grinding parameters and levels that affect surface integrity under different roughness conditions, providing a theoretical basis and practical reference.
