Water corrosion and dendrite growth seriously break the zinc plating/stripping process at the electrolyte/anode interface, causing the instability of the zinc metal anode of aqueous zinc batteries. Herein, a self‐consistent hydrophobic interface and orderly channels are assembled by three quaternary ammonium cationic surfactants, which can block the water erosion. Of particular interest, experimental results combined with theoretical calculation (DFT) reveals that the hydrophobic groups in quaternary ammonium cations are the determinaning factor in the kinetic process of zinc ion deposition and the life of the zinc anode. The massive micelles formed by benzyldimethyldodecylammonium with dodecyl and benzyl groups cause great hindrance to the transport and deposition of zinc ions. And dodecyltrimethylammonium with only a main hydrophobic group of dodecyl results in the higher polarization overpotential or voltage hysteresis for the zinc plating and lower coulombic efficiency (CE) < 99%. Surprisingly, the hydrophobic interface assembled by benzyltrimethylammonium (TMBA+) with a main benzyl group can inhibit side reactions and regulate zinc uniform deposition. And the batteries based on TMBA+ can achieve superb cycle stability with low voltage hysteresis and almost 100% CE. The proposed hydrophobic interface formed by quaternary ammonium cationic surfactants establishes pioneering work on zinc anode stability for zinc batteries and beyond.
A novel poly(phenazine‐alt‐pyromellitic anhydride) (PPPA) has been successfully designed and synthesized via a condensation polymerization strategy as promising cathode material in organic zinc‐ion batteries. Electrochemical quartz crystal microbalance (EQCM), FTIR and XPS characterizations verify a reversible Zn2+‐coordination mechanism in our PPPA cathode. Intriguingly, an ultrahigh Zn2+ diffusion coefficient of 1.2×10−7 cm2 s−1 was found in this large π‐conjugated system, which is the highest one among all organic cathode materials for zinc‐ion batteries. Theoretical calculations reveal the extended π‐conjugated plane in our PPPA sample results in a significant reduction on energy gap, effectively accelerating intramolecular electron transfer during charge/discharge process. Our finding provides insights to achieve high zinc‐ion transport kinetics by a design strategy on planar polymer system.
Rechargeable aqueous batteries based on ammonium‐ions shows great potential in low‐cost energy storage systems owing to their prominent superior characteristics, including ultrafast kinetics, long‐term lifespan, and environmental friendliness. Nevertheless, their development is severely challenged by the fact that the as‐reported cathode materials generally fail to satisfy the requirements on high capacity and stable working voltage simultaneously. Herein, the first NH4+ storage behavior in a MnAl layered double hydroxide (LDH) series is reported. Intriguingly, stable working voltage at 0.2 V is observed in the optimized Mn3Al1‐LDH sample with a high discharge capacity of 183.7 mAh g−1 at 0.1 A g−1. When assembling the rocking‐chair battery using a 3,4,9,10‐perylenetetracarboxylic diimide anode, the full battery delivers a high energy density of 45.8 Wh kg−1, surpassing most of its recently reported counterparts. A rapid amorphization conversion of the LDH cathode during the first charge process is revealed, which should be beneficial to NH4+ isotropic transport accompanied by a highly reversible building/breaking process of hydrogen bonds. The results realize a novel layered inorganic cathode material with superior performance for aqueous ammonium‐ion batteries, and the amorphization conversion to facilitate ion storage provides new insight into electrode design for aqueous batteries.
Zinc metal batteries show tremendous applications in wide-scale storages still impeded by aqueous electrolytes corrosion and interfacial water splitting reaction. Herein, a zincophobic electrolyte containing succinonitrile (SN) additive is proposed, the SN electrolyte shows a lower affinity for zinc but a stronger affinity for solid-state interphase (SEI). In the SN electrolyte, zinc hydroxide sulfate (ZHS) is more inclined to accumulate horizontally, forming a dense SEI protective layer on the surface of the Zn anode, effectively slowing down the corrosion of Zn and dendrite growth. The zincophobic SN electrolyte enables excellent performance: zinc plating/stripping Coulombic efficiency of 99.71% for an average of 400 cycles; stable cycles in a symmetric cell for 4000 h (0.9% zinc utilization) and 325 h (86.1% zinc utilization). The soft pack battery using limited zinc delivers maximum energy density of 57.0 Wh kg −1 (based on mass loading of cathode materials and anode materials). Such a simple additive strategy provides a theoretical reference for zinc chemistry in a mild electrolyte environment in practical applications.
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