Coupling Ferricyanide/Ferrocyanide Redox Mediated Recycling Spent LiFePO with Hydrogen Production.

Replacing the oxygen evolution reaction with thermodynamically more favorable alternative oxidation reactions offers a promising alternative to reduce the energy consumption of hydrogen production. However, questions remain regarding the economic viability of alternative oxidation reactions for industrial-scale hydrogen production. Here, we propose an innovative cost-effective, environment-friendly and energy-efficient strategy for simultaneous recycling of spent LiFePO (LFP) batteries and hydrogen production by coupling the spent LFP-assisted ferricyanide/ferrocyanide ([Fe(CN) ] /[Fe(CN) ] ) redox reaction. The onset potential for the electrooxidation of [Fe(CN) ] to [Fe(CN) ] is low at 0.87 V. Operando Raman and UV/Visible spectroscopy confirm that the presence of LFP in the electrolyte allows for the rapid reduction of [Fe(CN) ] to [Fe(CN) ] , thereby completing the [Fe(CN) ] /[Fe(CN) ] redox cycle as well as facilitating the conversion of spent LiFePO into LiOH ⋅ H O and FePO . The electrolyzer consumes 3.6 kWh of electricity per cubic meter of H produced at 300 mA cm , which is 43 % less than conventional water electrolysis. Additionally, this recycling pathway for spent LFP batteries not only minimizes chemical consumption and prevents secondary pollution but also presents significant economic benefits.