High‐Energy‐Density Magnesium‐Air Battery Based on Dual‐Layer Gel Electrolyte

Abstract

Mg-air batteries are explored as the next-generation power systems for wearable and implantable electronics as they could work stably in neutral electrolytes and are also biocompatible. However, high corrosion rate and low utilization of Mg anode largely impair the performance of Mg-air battery with low discharge voltage, poor specific capacity and low energy density. Here, to the best of our knowledge, we first report a dual-layer gel electrolyte to simultaneously solve the above two problems by preventing the corrosion of Mg anode and the production of dense passive layer, respectively. The resulting Mg-air batteries produced an average specific capacity of 2190 mAh g À1 based on the total Mg anode (99.3 % utilization rate of Mg anode) and energy density of 2282 Wh kg À1 based on the total anode and air electrode, both of which are the highest among the reported Mg-air batteries. Besides, our Mg-air batteries could be made into a fiber shape, and they were flexible to work stably under various deformations such as bending and twisting.Wearable and implantable electronic devices represent the next-generation electronics and are booming rapidly in the recent decade. [1][2][3] To stably and long-termly power these electronic devices, it is critical to make matchable and safe energy storage devices. [4][5][6][7] To this end, metal-air batteries with high energy densities have attracted increasing interests. [8,9] Among them, Mg-air batteries work stably in neutral electrolytes and are also biocompatible as Mg 2+ ions are harmless to the human body. [10][11][12] Therefore, Mg-air batteries are explored as promising candidates on the skin and inside the body.

Challenges and prospects of Mg-air batteries: a review

“…Metal-air batteries with gel-polymer electrolytes offer the advantages of safety, high energy density, and flexible design. In view of the mature research and application of polymer electrolytes for Li-air batteries [53] , gel-polymer electrolytes have also drawn great interest from researchers for Mg-air batteries [54,55] .…”

“…Liew et al designed an economical, inherently safe, and environmentally benign biopolymer WSGincorporated agar gel electrolyte for Mg-air batteries [54] . They investigated the effect of agar concentrations on electrolyte performance.…”

“…While in the Mg 2+ (Mg(TFSI) 2 )-containing [BMP][TFSI] electrolyte, the ORR was irreversible due to the formation of passivation layers limiting the diffusion of O 2 and O 2to/away from the electrode surfaces. The morphology and the chemical composition of the deposits formed on the electrodes after the [54] . (B) Discharge performance of Mg-air batteries with different WSG-incorporated agar gel electrolytes at the current density of 11.11 mA•cm -2 [54] .…”

“…The morphology and the chemical composition of the deposits formed on the electrodes after the [54] . (B) Discharge performance of Mg-air batteries with different WSG-incorporated agar gel electrolytes at the current density of 11.11 mA•cm -2 [54] . (C) Discharge curves of Mg-air batteries applying dual-layer gel and hydrogel electrolytes [55] .…”

A dual-electrolyte system for highly efficient Al–air batteries

“…Al–air, Mg–air, Zn–air, Li–air, and Na–air) possess many merits, such as high safety, environmental protection, and high energy density, exhibiting bright development and application prospects. 3–7 Among them, Al–air batteries demonstrate great potential due to their high specific capacity (2980 mA h g −1 ), the abundance of resources, and the low cost of Al. 8,9…”