Enhancing Proton Co-Intercalation in Iron Ion Batteries Cathodes for Increased Capacity

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous iron ion batteries (AIIBs) are promising for low-cost, sustainable energy storage.
• Current AIIBs face limitations due to low cathode capacity and poor Fe²⁺ intercalation kinetics.

Purpose of the Study:

• To enhance the capacity and rate capability of AIIBs cathode materials.
• To introduce a H⁺ and Fe²⁺ co-intercalation mechanism for improved battery performance.

Main Methods:

• Electrochemical activation to form an in situ FeOOH nanowire layer on the cathode.
• Investigating H⁺ and Fe²⁺ co-intercalation in iron hexacyanoferrate (FeHCF) and Na₄Fe₃(PO₄)₂(P₂O₇) (NFPP) cathodes.

Main Results:

• Activated FeHCF cathodes achieved a specific capacity of 151 mAh g^-1 with 93% retention over 500 cycles.
• The activation process doubled the capacity of NFPP cathodes.
• The FeOOH layer facilitated H⁺ co-intercalation, boosting performance.

Conclusions:

• The proposed H⁺/Fe²⁺ co-insertion electrochemistry significantly improves AIIB performance.
• This strategy enhances capacity and rate capability for various cathode materials.
• AIIBs with this co-intercalation mechanism represent a sustainable energy storage advancement.