Aqueous metal batteries routinely suffer from the dendritic growth at the anode, leading to significant capacity fading and ultimately, battery failure from short‐circuit. Herein, we utilize polyethylene glycol to regulate dendrite growth and improve the long‐term cycling stability of an aqueous rechargeable lithium/zinc battery. PEG200 in the electrolyte decreases the corrosion and chronoamperometric current densities of the zinc electrode up to four‐fold. Batteries with pre‐grown dendrites also perform significantly better when PEG is present in the electrolyte (41.4 mAh g−1 vs. 7.9 mAh g−1 after 1000 cycles). X‐ray diffraction and electron microscopy studies show that dendrites in the PEG‐containing electrolyte have been inhibited, leading to much smaller/smoother surface features than those of the control. The facile preparation process of the aqueous electrolyte combined with low cost and vast performance improvement in batteries of all sizes indicates high upscaling viability.

We have designed an aqueous gel electrolyte containing fumed silica as the thixotropic gelling agent and poly(ethylene glycol) (MW = 300 gmol -1 ) as the nonthixotropic gelling agent. Poly(ethylene glycol) is also the dendrite suppressor and the corrosion inhibitor. Both PEG300 and fumed silica can inhibit dendrite formation, shown by chronoamperometry results and ex-situ scanning electron microscopy images. Furthermore, the corrosion current density on the Zn anode in the 4wt.%FS-1wt.%PEG300 gel electrolyte is 27% less than that of the Zn in the reference aqueous

Aqueous lithium energy storage systems (ALESSs) offer several advantages over the commercially available nonaqueous systems, and the most noteworthy is that ALESSs have higher ionic conductivity, can be used safely, and are environmental-friendly in nature. The ALESS, however, exhibits faster capacity fading than their nonaqueous counterparts after repeated cycles of charge and discharge, thus limiting their wide-range applications. Excessive corrosion of metallic anodes in the aqueous electrolyte and accelerated growth of dendrites during the charge-discharge process are found to be the main reasons that severely impact the life span of ALESSs. Here, we introduce ultrathin graphene films as an artificial solid electrolyte interface (G-SEI) on the surface of a zinc anode to improve the cycling stability of an aqueous lithium battery system. The G-SEI is fabricated at different thicknesses and areas ranging from ∼1 to 100 nm and ∼1 to 10 cm, respectively, via a Langmuir-Blodgett trough method and deposited onto the surface of the zinc anode. Electrochemical characterizations show a significant reduction in corrosion current density (0.033 mA cm vs 1.046 mA cm for the control), suppression of dendritic growth (∼50%), and reduction in charge-transfer resistance (222 Ω vs 563 Ω for the control) when the G-SEI is utilized. The aqueous battery system with the G-SEI (100 nm thickness) on the anode exhibits ∼17% improvement in cycling stability (82% capacity retention after 300 cycles) compared to the control system. Comprehensive microscopy and spectroscopy characterizations reveal that the G-SEI not only controls the ion transport between the electrolyte and the anode surface (lower corrosion) but also promotes a uniform deposition (less dendritic growth) of zinc on the anode.

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