Anion-Regulated Deposition-Dissolution Chemistry in Acidic Aqueous Indium─MnO₂ Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Acidic aqueous metal-MnO2 rechargeable batteries offer high capacity via MnO2/Mn2+ redox chemistry.
• These batteries face challenges including severe anode corrosion and poor reversibility in acidic media.
• Developing stable electrode interfaces is crucial for advancing acidic battery technologies.

Purpose of the Study:

• To report a novel acidic Indium-Manganese dioxide (IMB) battery system.
• To investigate anion-regulated interfacial chemistry for reversible electrode reactions.
• To enhance the performance and stability of acidic rechargeable batteries.

Main Methods:

• Systematic investigation of anion effects (Cl-, SO4 2-) on Indium deposition and MnO2 reversibility.
• Development of tailored Cl-/SO4 2- ratios and an anion-decoupled dual-electrolyte configuration.
• Demonstration of an electrode-less IMB using a Bismuth (Bi) substrate for in situ alloying.

Main Results:

• The In-MnO2 battery operates at ~1.7 V with 72.3% energy efficiency and over 1500 cycles.
• Concentrated Cl- anions promote uniform Indium deposition, while SO4 2- enhances MnO2 reversibility.
• The electrode-less IMB achieves over 2000 cycles, delivering high energy density (484.5 Wh kg-1) and cumulative capacity (4120 mAh cm-2).

Conclusions:

• Anion-regulated interfacial chemistry enables reversible deposition-dissolution reactions in acidic IMBs.
• Tailored electrolyte compositions and substrate engineering are key for high-performance acidic batteries.
• This work establishes a design paradigm for advanced acidic rechargeable battery systems.