Overlooked residue of Li-ion battery recycling waste as high-value bifunctional oxygen electrocatalyst for Zn-air batteries

Funding Information: This research has been supported by the Estonian Research Council (PUTJD1029, PSG312), the European Regional Development Fund (projects no: 2014-2020.4.01.16-0041 and 2014-2020.4.01.15-0005), the Environmental Investment Centre (KIK 17988), as well as the Business Finland BatCircle2.0 project (Grant Number 44886/31/2020). Additionally, the Academy of Finland's RawMatTERS Finland Infrastructure (RAMI) based at Aalto University and the OtaNano - Nanomicroscopy Center (Aalto-NMC) were utilized as part of this research. Publisher Copyright: © 2023 The Authors Continuously increasing production of Li-ion batteries (LIBs) for the Green Transition is underlined by the absence of feasible recycling methods for graphite, regardless of its criticality as a raw material. The current study demonstrates a novel strategy to valorize waste graphite as a valuable raw material in oxygen electrocatalyst production. Industrially produced LIBs post-metallurgical leach residue was transformed into highly active bifunctional oxygen electrocatalyst, which was subsequently successfully applied as an active catalyst for Zn-air batteries. Moreover, produced graphene-like material was in-situ doped by the impurity cobalt present in the recycling residue. The resultant Zn-air battery was shown to deliver a high specific capacity of 719 mA h g-1, peak power density of 112.8 mW cm-2 and could be cycled over 400 times. Results clearly demonstrate that an often-neglected LIB recycling waste fraction can be a valuable source for electrocatalysts production required in metal-air batteries and regenerative fuel cells.