Capitalizing on the Iodometric Reaction for Energetic Aqueous Energy Storage

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Iodometric titrations are common for Cu²⁺ determination but face challenges in electrochemical energy storage.
• Poor reversibility and iodide/triiodide (I^-/I₃^-) shuttling limit the use of Cu²⁺ in batteries.

Purpose of the Study:

• To develop a separator that mitigates ion shuttling for improved Cu²⁺ utilization in energy storage.
• To investigate the mechanism of ion suppression using a 4A zeolite separator.
• To evaluate the performance of a Cu²⁺-mediated hybrid aqueous battery.

Main Methods:

• Fabrication and characterization of a 4A zeolite separator.
• Electrochemical testing of a Zn∥I₂ hybrid cell with the zeolite separator.
• Theoretical and experimental analysis of electrostatic interactions between zeolite and triiodide ions.

Main Results:

• The 4A zeolite separator significantly suppressed triiodide (I₃^-) shuttling.
• Achieved record-high capacity retention of 95.7% over 600 cycles.
• Assembled Zn∥I₂ hybrid cell demonstrated a discharge capacity of 356 mA h g^-1 and specific energies of 443 W h kg^-1 (based on I₂) or 193 W h kg^-1 (based on both electrodes).

Conclusions:

• Zeolite separators effectively prevent triiodide (I₃^-) shuttling via electrostatic repulsion.
• Cu²⁺-mediated aqueous batteries show promise for high-capacity energy storage.
• This approach offers a pathway to double the capacity and energy of conventional aqueous battery systems.