MnO₂|Mg(Ac)₂|V₆O_13-x: An Aqueous Full Cell for High-Performance Magnesium-Ion Storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous magnesium-ion batteries (AMIBs) are attractive for energy storage due to their low cost and high safety.
• Magnesium metal anodes are unstable in aqueous electrolytes, hindering AMIB development.
• Vanadium oxide is a potential anode material but suffers from low conductivity and sluggish kinetics.

Purpose of the Study:

• To investigate the potential of oxygen-deficient vanadium oxide (V₆O_13-x) as an efficient anode for AMIBs.
• To explore the impact of oxygen defect engineering on the electrochemical performance of vanadium oxide in AMIBs.
• To demonstrate the viability of V₆O_13-x in a full AMIB system.

Main Methods:

• Synthesis of oxygen-deficient V₆O_13-x.
• Electrochemical characterization of V₆O_13-x as an anode in AMIBs.
• Assembly and testing of a MnO₂|Mg(Ac)₂|V₆O_13-x full cell.

Main Results:

• Oxygen defect engineering in V₆O_13-x significantly accelerates Mg²⁺ and charge transfer.
• V₆O_13-x exhibits excellent rate capabilities (298.2 mAh g^-1 at 1.0 A g^-1) and cycle stability (123.1 mAh g^-1 at 5.0 A g^-1 after 1,500 cycles with 85% retention).
• The full cell demonstrates a reversible capacity of 159.2 mAh g^-1 at 0.2 A g^-1 and stable cycling for 3,000 cycles at 2.0 A g^-1.

Conclusions:

• Oxygen-deficient V₆O_13-x is a highly effective anode material for AMIBs.
• Defect engineering is a viable strategy to overcome the limitations of vanadium oxide anodes.
• This research offers a novel pathway towards high-performance and stable aqueous magnesium-ion batteries.