Mechanistically Engineered Heterojunction From Spent LFP for Efficient Oxygen Evolution Electrocatalysis.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Chemistry

Background:

• Large-scale retirement of lithium iron phosphate (LFP) batteries necessitates sustainable recycling and repurposing strategies.
• The inert nature of spent LFP materials limits their direct application in catalysis.
• Developing efficient electrocatalysts for oxygen evolution reaction (OER) is crucial for water-splitting technologies.

Purpose of the Study:

• To develop a structure-guided strategy for upcycling spent LFP batteries into high-performance OER electrocatalysts.
• To investigate the mechanism of the upcycled catalyst in chloride-containing electrolytes.
• To assess the economic viability of the proposed upcycling method.

Main Methods:

• Mild air oxidation of spent LFP to form Li3Fe2(PO4)3 (LFP(III)) with α-Fe2O3 nanodots.
• Spatially selective growth of NiO on α-Fe2O3 to create p-NiO/n-Fe2O3 heterojunctions.
• In situ Raman and XPS analyses to study catalytic mechanisms and material stability.
• Electrochemical testing in chloride-containing electrolytes to evaluate OER performance and durability.

Main Results:

• The upcycled LFP(III)/NiO catalyst exhibits a well-defined p-NiO/n-Fe2O3 heterojunction.
• The catalyst demonstrates efficient OER activity with low overpotentials (268 mV at 10 mA cm⁻² and 292 mV at 100 mA cm⁻²).
• The phosphate-rich matrix effectively suppresses halide corrosion, ensuring excellent durability.
• Techno-economic analysis shows a six-fold cost-efficiency improvement over conventional recycling.

Conclusions:

• A novel, energy-efficient strategy upcycles spent LFP batteries into advanced OER electrocatalysts.
• The developed catalyst offers superior performance and durability in challenging electrolytes.
• This approach bridges battery waste management with functional catalyst design, advancing sustainable materials chemistry and water-splitting applications.