Due to the great advantages of low cost, high capacity, and excellent safety, the Zn metal is a promising candidate material for rechargeable aqueous battery systems. However, its practical applications have been restricted by the uncontrollable dendrite growth and electrode side reactions (such as corrosion, passivation, and hydrogen evolution reactions) during the plating process. Herein, we reveal that the dendrite growth would expose the electrode to more highly active tips, exacerbating the passivation of the electrode and the decomposition of the electrolyte by in situ optical microscopies. We propose a low-cost, nontoxic, low-concentration (less than 1 g/L), and effective electrolyte additive, saccharin sodium, which can guide an even Zn deposition without obvious electrode side reactions in the charge/discharge process. The saccharin anion acts as a “traffic assistant” of Zn2+ and demonstrates its great potential for practical application. The assembled Zn symmetrical battery shows an excellent cycling performance at a high current density and capacity (an extremely long cycle life over 3800 h is obtained at 5 mA/cm2 and 8 mA h/cm2, and 20 mA/cm2 and 5 mA h/cm2 show a lifetime over 800 h), and the full cell (coupled to an AC electrode) presents a stable cycle life with a capacity retention of 86.4% even after 8000 cycles at 5 mA/cm2. The saccharin sodium proposed in this work is promising to solve the anode problems in advanced Zn batteries.

Because of its safety, cost-effectiveness, and environmental friendliness, aqueous zinc ion batteries (ZIBs) have aroused the wide interest of researchers. In particular, the use of Z foil as an anode of ZIBs has a higher theoretical capacity and simplifies the battery manufacturing process. However, serious problems occur at the electrode/electrolyte interface, such as dendrite growth and side reactions, making the coulombic efficiency and lifetime of Zn-metal electrodes far from satisfactory. This has aroused interest in researchers seeking various additives to solve those above problems. For the rapid development of electrolyte additives in this new field, it is necessary to provide theoretical support. The electroplating of metal zinc has been developed for nearly two centuries. A rich theoretical basis and various efficient electroplating additives have been developed to improve the structure and properties. Furthermore, the essence of conventional electroplating and Zn plating for ZIBs is parallel. This review starts from the basic theory of electroplating and relates the application of electroplating additives in reversible ZIBs. The basic and new understanding of traditional electroplating additives applied to high-performance ZIBs is summarized, providing guidance for accurate evaluation and analysis of high-efficiency ZIBs electrolyte additives in the near future

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A facile and simple strategy to modify polypropylene (PP) separators with dopamine (DA) and polyethylenimine (PEI) has been proposed. The cross-linked DA-PEI nanoparticles can be adsorbed to the PP separator by the quinonyl groups of DA efficiently. The electrolyte wettability of the modified separator is obviously improved. The Li-S battery with the modified separator delivers a high cycling capacity and rate capacity. The specific capacity of Li-S battery with A1P3 separator is 1033.4 mA h g−1 and stabilizes at 470.8 mA h g−1 at 0.2 C after 100 cycles. And its rate capacity at 0.2 C, 0.5 C, 1 C, and 2 C is 1016.5 mA h g−1, 754.6 mA h g−1, 676.2 mA h g−1, and 463.6 mA h g−1, respectively. The outstanding electrochemical performance could be ascribed to that the polar deposited layer, which not only alleviates the shuttle effect by physical blocking and electrostatic interactions, but also facilitates Li+ ions migration by the improved electrolyte wettability.

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