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.
The use of thixotropic gel electrolytes in the rechargeable hybrid aqueous battery improves the battery performance but it is required to have a corrosion inhibitor in the gel electrolyte. These inhibitors are not always friendly to the environment. In this work, we use lignin -a renewable material -to neutralize strong acid sites of the fumed silica gelling agent prior to gel preparation. Linear polarization, chronoamperometry, and ex-situ scanning electron microscopy examinations show that the new gel electrolyte reduces the corrosion on zinc (up to 43%) and supports planar zinc deposit. In other words, the shape of the zinc surface is controlled and it is further confirmed by the XRD and SEM of post-battery run anodes. Moreover, the battery using this new lignin coated fumed silica based gel electrolyte exhibits a float charge current as low as 0.0025 mA after 24 hours of monitoring, which is 30.6% lower than the reference. The capacity retention of gelled battery is as high as 82%after 1000 cycles at 4 C, which is 14% higher than the reference battery using reference liquid electrolyte under the same CC-CV test, complemented by lower self-discharge and higher rate capability. The results lead the team nearer to a commercializable gelled battery system.
It has been recently reported that the fluorescence of some DNA templated silver nanoclusters (AgNCs) can be significantly enhanced upon hybridizing with a partially complementary DNA containing a Grich overhang near the AgNCs. This discovery has found a number of analytical applications but many fundamental questions remain to be answered. In this work, the photostability of these activated AgNCs is reported. After adding the G-rich DNA activator, the fluorescence intensity peaks in ~1 h and then starts to decay, where the decaying rate is much faster with light exposure. The lost fluorescence is recovered by adding NaBH4, suggesting that the bleaching is an oxidative process.Once activated, the G-rich activator can be removed while the AgNCs still maintain most of their fluorescence intensity. UV-vis spectroscopy suggests that new AgNC species are generated upon hybridization with the activator. The base sequence and length of the template DNA have also been varied, leading to different emission colors and color change after hybridization. G-rich aptamers can also serve as activators. Our results indicate that activation of the fluorescence by G-rich DNA could be a convenient method for biosensor development since the unstable NaBH4 is not required for the activation step.
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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