Performance of Al-0.5In as Anode for Al–Air Battery in Inhibited Alkaline Solutions

Abstract

In this research, the performance of Al-air batteries based on pure Al and Al-0.5 wt%In anodes in 4M NaOH solutions with or without different concentrations of additives was investigated by galvanostatic discharge test. The characteristics of the anodes after discharge were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive analysis of X-ray (EDAX). The corrosion behavior of the anodes was researched by self-corrosion rate test and potentiodynamic polarization test. The results show that the Al-In alloy exhibits a low self-corrosion rate and high anodic efficiency when ZnO or Na 2 SnO 3 is added to 4M NaOH. The results of galvanostatic discharge at 20 mAcm −2 indicate that the Al-air battery based on Al-0.5 wt%In anode shows excellent discharge performance. The Al-air battery based on the alloy anode has an operating voltage of 1.3 V and anodic efficiency of 75.2% in 4M NaOH with 0.02M Na 2 SnO 3 , and an operating voltage of 1.01 V and anodic efficiency of 82.5% in 4M NaOH with 0.2M ZnO. SEM and EDAX results prove that zinc oxide or sodium stannate could inhibit the corrosion of the Al-In anode by the deposition of zinc or tin on the anode surface.Aluminum is an excellent anode material for metal-air batteries because of its high theoretical electrochemical equivalent value (2980 mAh g -1 ), which is just lower than that of lithium (3860 mAh g -1 ) and higher than those of other metals such as magnesium (2200 mAh g -1 ) and zinc (820 mAh g -1 ). 1 As promising power and energy storage devices, Al-air batteries can be applied in fields such as electric vehicles, navigation and portable sources. In addition, the final reaction product can be recovered as aluminum during recycling. However, severe self-corrosion of the aluminum anode in alkaline electrolyte causes fuel loss during standby. A protective oxide film forms spontaneously on the aluminum surface in neutral electrolyte, which slows down the active dissolution of the aluminum anode. These problems have hindered the development and business applications of Al-air batteries. 2,3 Two main methods have been proposed to inhibit the self-corrosion of aluminum anodes in alkaline solution. The first method is to dope aluminum with active metal elements. The active metal elements mainly include Ga, In, Sn, Zn and Mg. 4 As they have high hydrogen evolution overpotential, these alloying elements can reduce hydrogen evolution. An Al-air battery based on Al-1 wt%Mg-1 wt%Zn-0.1 wt%Ga-0.1 wt%Sn anode in 4M NaOH solution showed excellent discharge performance. 5 However, the addition of excessive kinds of elements is harmful to the recovery of aluminum. What's more, the amount of active metal elements added into the aluminum should be as low as possible. Therefore, researchers preferred to study some binary aluminum alloys as anodes of Al-air batteries. 6-9 For instance, Wilhelmsen studied the corrosion rate of Al-0.1 wt%In anode in 4M KOH solution by the weight loss method and the result revealed that t...

Corrosion and Discharge Behaviors of Al-Mg-Sn-Ga-In in Different Solutions

“…Moreover, Alloy 2 presents scalloped surface in the close-up view (Fig. 9d), and similar scalloped surface is also observed in Al-In alloys (Ref 4,9). Reports show that In element promotes an enrichment of Cl À at the metal surface (Ref 21) and the presence of In element in the alloy enhances the adsorption of Cl À at the electrode surface (Ref 10), leading to the observed activity of Al matrix.…”

“…Research of alloy anodes for Al-air batteries has focused on magnesium (Mg), zinc (Zn), tin (Sn), gallium (Ga), indium (In), and manganese (Mn) elements, because these elements can significantly modify the electrochemical activity and the anti-corrosion property of Al anodes (Ref 8). In previous studies, binary and ternary alloys were reported, such as Al-Ga, Al-Sn, Al-In, and Al-In-Ga alloys ( Ref 4,9,10). Research results also show that Al-air batteries can use either alkaline or brine electrolytes, such as NaCl or NaOH solution ( Ref 8,14,15).…”

“…The measuring frequency range was from 100 kHz to 0.1 Hz. Figure 1 shows the schematic diagram for Al-air battery test, a similar equipment as described in the previous report (Ref 9). Al-air batteries based on two alloy anodes were assembled and the cathode was air electrode with MnO 2 .…”

Recent Progress and Future Trends of Aluminum Batteries

“…20) is 2.74 V, [122][123] the practical voltages are limited to 1.2 to 1.6 V because of the intricate electrode processes occurring at the Al anode. [120,[124][125][126][127][128][129][130][131] The morphology, structure, grain size and crystal orientation also show great effect on the electrode reactions and cell performance. [120,[124][125][126][127][128][129][130][131] The morphology, structure, grain size and crystal orientation also show great effect on the electrode reactions and cell performance.…”

“…[120] Many efforts, such as using polynary Al alloys with Ga, Sn, Mg, In, Zn, Mn, Bi, Pb, Tl and Hg, have been made to better the electrochemical parameters of Al-air cell, including improving the open-circuit voltage (OCV) and decreasing the parasitic reactions at the anode. [120,[124][125][126][127][128][129][130][131] The morphology, structure, grain size and crystal orientation also show great effect on the electrode reactions and cell performance. [120,[132][133][134] For the electrolyte part, some additives like cationic surfactant, (In(OH) 4 À ), (SnO 3 2À ), zinc oxide and plant extracts have been proposed to suppress the evolution of hydrogen, corrosion and dissolution of Al metal electrode, leading to better performance.…”