Simultaneous regulation on electrolyte structure and electrode interface with glucose additive for high-energy aluminum metal-air batteries

Abstract

Aqueous metal-based batteries have attracted great attention due to their high energy density and high safety. However, currently suppressing the severe parasitic hydrogen evolution reaction (HER) at the metal anodes in aqueous electrolytes remains challenging. Here, a novel “two birds with one stone” strategy of simultaneously reducing water activity and constructing a protective layer on Al anode with a green and low-cost glucose additive is proposed to suppress the HER. Theoretical studies and experimental characterizations confirm that the glucose additive could reduce water activity via the “molecular crowding effect” and form an organic protective layer on Al metal via chemical adsorption. The dual-functional glucose additive exhibits significant suppression on the HER and self-discharge of Al-metal anodes, which endows a flow-based Al-air battery with ultra-high specific capacity of 2886.7 mAh g_Al⁻¹ and energy density of 3675.1 Wh kg_Al⁻¹. This study not only blazes a new path for suppressing HER on Al-metal anodes but also casts new light on aqueous electrolyte design and the stabilization of metal anodes.