Effect of quinoline-8-sulfonic acid and CaO as hybrid electrolyte additives on microstructure and property of AA5052 alloy anode for aluminum-air battery

Boosting the Performance of Aluminum-Air Batteries by Interface Modification

The large-scale application of aqueous Al-air batteries is highly restricted by the performance of Al anodes. The severe self-corrosion and hydrogen evolution of the Al anode in a concentrated alkaline electrolyte are the main reason. Here, aimed at relieving side reactions and enhancing the utilization of metal Al, we propose a hybrid electrolyte additive of 2-mercaptobenzothiazole (MBT) and ZnO to form a protective film at the anode/electrolyte interface and to decrease the hydrogen evolution active site. The strong absorption capability of MBT on the metal surface, along with the reduced Zn-containing layer, enables a compact protective film with high hydrogen evolution potential on the Al surface. With this benefit, the hydrogen evolution reaction (HER) inhibition efficiency is up to 83.58%, endowing a superior Al-air battery with an energy density of 2376.71 Wh kgAl-1 under a current density of 25 mA cm-2. The conception of constructing a hybrid protective film on the metal surface not only favors the development of metal-air batteries but also facilitates metal corrosion protection.

Self-assembly of an amino acid derivative as an anode interface layer for advanced alkaline Al-air batteries

Alkaline Al-air batteries (AABs) are gaining increasing attention for large-scale energy storage systems due to their attractive intrinsic safety and cost-effectiveness. Nonetheless, the future development of AABs is substantially hampered by water-induced self-corrosion processes on the Al anode. In this work, we introduce an amino acid derivative, namely Nα-Boc-N1-formyl-L-tryptophan (NBLT), into a 4 M NaOH electrolyte to construct a unique layer that can effectively regulate the surface microstructure of the Al anode. The findings of the experiments show that NBLT can be used as a reliable corrosion inhibitor. The effectiveness of such inhibitors increases with NBLT concentration, reaching a maximum of 73.9% at 1.5 mM. In comparison to the pristine condition, there is a significant increase in anode utilization from 31.8% to 82.9%, capacity density from 947.9 to 2469.1 mA h g-1, and energy density from 1261.6 to 3384.6 W h kg-1. Theoretical calculations indicate that the carboxyl moieties present in the NBLT molecule establish coordination bonds with the Al atoms, thereby exerting a dominant role in the formation of the self-assembled barrier. The present investigation paves an effective strategy to inhibit reactions between anodes and electrolytes for advanced AABs.

La-based perovskites for capacity enhancement of Li-O2 batteries

Li-O2 batteries are a promising technology for the upcoming energy storage requirements because of their high theoretical specific energy density of 11,680 Wh kg-1. Currently, the actual capacity of Li-O2 batteries is much lower than this theoretical value. In many studies, perovskites have been applied as catalysts to improve the air electrode reactions in Li-O2 batteries. The effects of structure and doping on the catalytic activity of perovskites are still unclear. La1-xSrxCoO3-δ (x = 0.1, 0.3, and 0.5) and La0.9Sr0.1YbO3-δ mixed with carbon black (Vulcan XC500 or Super P) were used as air electrode catalysts. Electrochemical characterizations were conducted using a Swagelok-type cell. The charge-discharge capacity and cyclic voltammetry (CV) performance were investigated in this study. The La1-xSrxCoO3-δ (x = 0.1, 0.3, and 0.5) is a suitable cathode catalyst for Li-O2 batteries. In this study, the La0.5Sr0.5CoO3-δ/Super P cathode demonstrated the highest discharge capacity (6,032 mAh g-1). This excellent performance was attributed to the large reaction area and enhanced Li2CO3 generation.

Effect of Indole-2-carboxylic Acid on the Self-Corrosion and Discharge Activity of Aluminum Alloy Anode in Alkaline Al-Air Battery

Al-air battery has been regarded as a promising new energy source. However, the self-corrosion of aluminum anode leads to a loss of battery capacity and a decrease in battery longevity, limiting its commercial applications. Herein, indole-2-carboxylic acid (ICA) has been added to 4 M NaOH as a corrosion inhibitor. Its impact on the self-corrosion of aluminum alloy and the enhancement of the functionality of Al-air batteries at various concentrations have been investigated. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques have been used to examine the compositional and morphological alterations of aluminum alloy surfaces. Electrochemical and hydrogen evolution tests showed that indole-2-carboxylic acid is an efficient corrosion inhibitor in alkaline solutions, and its impact grows with concentration. Our findings demonstrated that when the inhibitor concentration is 0.07 M, the inhibition efficiency is 54.0%, the anode utilization rises from 40.2% to 79.9%, the capacity density increases from 1197.6 to 2380.9 mAh g^-1, and the energy density increases from 1469.9 to 2951.8 Wh kg^-1. In addition, theoretical calculations have been performed to support the experimental results.

Regulating the Anode Corrosion by a Tryptophan Derivative for Alkaline Al-Air Batteries

Screening a green corrosion inhibitor that can prevent Al anode corrosion and enhance the battery performance is highly significant for developing next-generation Al-air batteries. This work explores the non-toxic, environmentally safe, and nitrogen-rich amino acid derivative, N(α)-Boc-l-tryptophan (BCTO), as a green corrosion inhibitor for Al anodes. Our results confirm that BCTO has an excellent corrosion inhibition effect for the Al-5052 alloy in 4 M NaOH solution. An optimum inhibitor addition (2 mM) has increased the Al-air battery performance; the corrosion inhibition efficiency was 68.2%, and the anode utilization efficiency reached 92.0%. The capacity and energy density values increased from 990.10 mA h g^-1 and 1317.23 W h kg^-1 of the uninhibited system to 2739.70 mA h g^-1 and 3723.53 W h kg^-1 for the 2 mM BCTO added system. The adsorption behavior of BCTO on the Al-5052 surface was further explored by theoretical calculations. This work paves the way for constructing durable Al-air batteries through an electrolyte regulation strategy.