Using Recovered Lithium Iron Phosphate Battery Materials as Efficient Electrocatalysts for the Oxygen Evolution Reaction

Abstract

The rapid emergence of lithium-ion batteries (LIBs) to satisfy our ever increasing energy demands will result in a significant future waste problem at their end of life. Lithium iron phosphate (LFP) as a cathode material is now widely used in LIBs with increasing market share. It is expected that there will be significant volumes of battery waste containing this material in the near future, and therefore it is important to develop methods for effectively repurposing this LFP waste to mitigate its impact on the environment. In this work we demonstrate the repurposing of LFP from spent LIBs as electrocatalysts for the oxygen evolution reaction (OER) which is critical to electrochemical water splitting and the production of green hydrogen. Our study has shown that the recovered LFP once immobilized onto a Ni substrate reconstructs into a mixed Fe/Ni oxide surface layer which is highly active for the OER. Promisingly, the LFP recovered from batteries that were cycled multiple times (up to 100 cycles) showed excellent electrocatalytic performance with a low Tafel slope of 58 mV dec⁻¹, overpotential values of 250 and 310 mV to reach 10 and 100 mA cm⁻², respectively and 24 h stability at over 200 mA cm⁻². This research provides potential motivation for recycling companies to isolate LFP from spent Li ion batteries for later use in water electrolysis technologies.