Polymer electrolyte-modified semi-solid iron anodes for efficient hydrogen evolution reaction suppression and highly...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous iron-ion batteries face challenges with iron anode reversibility due to the hydrogen evolution reaction (HER).
• HER is thermodynamically favored over Fe²⁺ electroplating in acidic electrolytes, leading to low coulombic efficiency and short cycle life.
• Existing anode designs are limited by direct contact with aqueous electrolytes.

Purpose of the Study:

• To develop a novel semi-solid iron anode (SSIA) to overcome HER limitations in aqueous iron-ion batteries.
• To enhance the coulombic efficiency and cycling stability of iron anodes.
• To provide insights for designing advanced anode materials for grid-scale energy storage.

Main Methods:

• Fabrication of a semi-solid iron anode (SSIA) using Fe powder and Super P encapsulated in polyethylene glycol (PEG) with Fe(CF₃SO₃)₂.
• Encapsulation isolates the iron anode from the aqueous electrolyte, mitigating HER.
• Testing of symmetric cells in 1 M Fe(CF₃SO₃)₂ electrolyte to evaluate performance.

Main Results:

• The SSIA effectively mitigated the hydrogen evolution reaction by isolating the iron anode.
• Achieved a high coulombic efficiency of 97% in 1 M Fe(CF₃SO₃)₂ electrolyte.
• Demonstrated stable cycling of symmetric cells for over 1400 hours at 0.1 mA cm^-2.

Conclusions:

• The novel SSIA design significantly improves anode reversibility and cycling stability in aqueous iron-ion batteries.
• This strategy effectively suppresses HER, paving the way for more efficient iron-based energy storage.
• The findings offer valuable insights for the development of advanced anode materials for grid-scale applications.