Water soluble graphene as electrolyte in mg-air battery

What is it about?

Magnesium-air (Mg-air) batteries are an important energy source used to power electronic equipment and automobiles. Metal-air batteries give more energy density due to surplus air involved in reduction reaction at air cathode. In this study, the scope of improvements in the efficiency of Metal-air batteries is investigated through addition of water soluble graphene (WSG) as inhibitor in NaCl electrolyte. The discharge performance, corrosion behaviour and electrochemical impedance are studied for (i) the conventional Mg-air battery using 3.5% NaCl and (ii) Mg-air battery with WSG-based 3.5% NaCl electrolyte. X-ray diffraction analysis for WSG is carried out and it shows the crystalline nature of WSG by an intense sharp peak at 26.3. Scanning electron microscope study is also performed and shows the flakelike structure of WSG denoted by thin layers of carbon. The immersion of WSG in 3.5% NaCl electrolyte increased the current density from 13.24 to 19.33 mA cm2. Meanwhile, the WSG-based Mg-air battery was found to hold specific discharge capacity of 1030.71 mAh g1, which was higher than that obtained in 3.5% NaCl electrolyte (i.e., 822.85 mAh g1). The WSG-based Mg-air battery shows good self-discharge capacity and higher electrochemical activity during discharge.

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Why is it important?

The aim of this study was to investigate the utility of watersoluble graphene (WSG) as a catalyst additive in a salt electrolyte for Mg-air battery and to determine its impact on the performance of battery. Doping of graphene sheets with poly (sodium 4- styrenesulfonate) has been carried previously to disperse graphene in aqueous solution ; however this study did not investigate the utility of using graphene as a catalyst in an electrolyte in Mg-air battery to enhance the discharge capacity of the WSG-based Mg-air battery.

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