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Aqueous zinc-ion batteries are regarded as one of the new promising rechargeable batteries. However, serious Zn dendrite growth causes short-circuit issues in the batteries. Herein, we report that arginine (Arg), a cationic surfactant electrolyte additive, can inhibit irregular and nonplanar dendrite growth and induce uniform Zn deposition. It shows a long cycle life (515 h) of Zn/Zn cells in the electrolyte containing Arg, which is ∼10 times longer than that of the electrolyte with no additive. The hydrolysis of Arg produces arginine cations (Arg + ), which will be preferentially adsorbed on Zn dendrites due to the tip charge accumulation effect during the Zn plating process. Arg + increases the overpotential for the nucleation of Zn dendrites and results in uniform Zn deposition. After about 350 cycles, the MnO 2 /Zn cell shows 84.59% capacity retention and 99.85% average Coulomb efficiency in the electrolyte with the additive. The low-cost and nontoxic electrolyte additive identified in this work provides a new pathway toward inducing regular Zn deposition morphology.

Abstract. Limiting fuel sulfur content (FSC) is a widely adopted approach for reducing ship emissions of sulfur dioxide (SO2) and particulate matter (PM), particularly in emission control areas (ECAs), but its impact on the emissions of volatile organic compounds (VOCs) is still not well understood. In this study, emissions from ships at berth in Guangzhou, southern China, were characterized before and after the implementation of the fuel switch policy (IFSP) with an FSC limit of 0.5 % in the Pearl River Delta ECA (ECA-PRD). After IFSP, the emission factors (EFs) of SO2 and PM2.5 for the coastal vessels decreased by 78 % and 56 % on average, respectively; however, the EFs of the VOCs were 1807±1746 mg kg−1, approximately 15 times that of 118±56.1 mg kg−1 before IFSP. This dramatic increase in the emissions of the VOCs might have been largely due to the replacement of high-sulfur residual fuel oil with low-sulfur diesel or heavy oils, which are typically richer in short-chain hydrocarbons. Moreover, reactive alkenes surpassed alkanes to become the dominant group among the VOCs, and low-carbon-number VOCs, such as ethylene, propene and isobutane, became the dominant species after IFSP. As a result of the largely elevated EFs of the reactive alkenes and aromatics after IFSP, the emitted VOCs per kilogram of fuel burned had nearly 29 times greater ozone formation potential (OFP) and approximately 2 times greater secondary organic aerosol formation potential (SOAFP) than those before IFSP. Unlike the coastal vessels, the river vessels in the region used diesel fuels consistently and were not affected by the fuel switch policy, but the EFs of their VOCs were 90 % greater than those of the coastal vessels after IFSP, with approximately 120 % greater fuel-based OFP and 70 %–140 % greater SOAFP. The results from this study suggest that while the fuel switch policy could effectively reduce SO2 and PM emissions, and thus help control PM2.5 pollution, it will also lead to greater emissions of reactive VOCs, which may threaten ozone pollution control in harbor cities. This change for coastal or ocean-going vessels, in addition to the large amounts of reactive VOCs from the river vessels, raises regulatory concerns for ship emissions of reactive VOCs.

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