Marine oil contamination remediation remains a worldwide challenge. Siphon action provides a spontaneous, continuous, low-cost and green route for oil recovery. However, it is still limited by the low oil...
The flow behavior of oil in nanochannels has attracted extensive attention for oil transport applications. In most, if not all, of the prior theoretical simulations, oil molecules were observed to flow steadily in nanochannels under pressure gradients. In this study, non-equilibrium molecular dynamics simulations are conducted to simulate the Poiseuille flow of oil with three different hydrocarbon chain lengths in graphene nanochannels. Contrary to the conventional perception of steady flows of oil in nanochannels, we find that oil molecules with the longest hydrocarbon chain (i.e., n-dodecane) exhibit notable stick−slip flow behavior. An alternation between the high average velocity of n-dodecane in the slip motion and the low average velocity in the stick motion is observed, with a drastic, abrupt velocity jolt of up to 40 times occurring at the transition in a stick−slip motion. Further statistical analyses show that the stick−slip flow behavior of n-dodecane molecules originates from the molecular alignment change of oil near the graphene wall. The molecular alignment of n-dodecane shows different statistical distributions under stick and slip motion states, leading to significant changes of friction forces and thus notable velocity fluctuations. This work provides new insights into the Poiseuille flow behavior of oil in graphene nanochannels and may offer useful guidelines for other mass transport applications.
The poor reversibility of Zn metal anodes arising from water‐induced parasitic reactions poses a significant challenge to the practical applications of aqueous zinc‐ion batteries (AZIBs). Herein, a novel quasi‐solid‐state “water‐in‐swelling‐clay” electrolyte (WiSCE) containing zinc sulfate and swelling clay, bentonite (BT), is designed to enable highly reversible Zn metal anodes. AZIB full cells based on the WiSCE exhibit excellent cyclic stability at various current densities, long shelf life, low self‐discharge rate, and outstanding high‐temperature adaptability. Particularly, the capacity of WiSCE‐based AZIB full cells retains 90.47% after 200 cycles at 0.1 A g−1, 96.64% after 2000 cycles at 1 A g−1, and 88.29% after 5000 cycles at 3 A g−1. Detailed density functional theory calculations show that strong hydrogen bonds are formed between BT and water molecules in the WiSCE. Thus, water molecules are strongly confined by BT, particularly within the interlayers, which significantly inhibits water‐induced parasitic reactions and greatly improves cyclic stability. Compared to the state‐of‐the‐art “water‐in‐salt” electrolytes, the WiSCE can provide a significantly higher capacity at the full‐cell level with a substantially reduced cost, which is promising for the design of next‐generation high‐performance AZIBs. This work provides a new direction for developing cost‐competitive AZIBs as alternatives to grid‐scale energy storage.
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