Regenerating Spent Lithium-Ion Battery Cathodes as Dual-Functional Biocatalysts for Highly-Efficient Oxygen and Hydrogen Evolution Using <i>Aspergillus niger</i> Soluble Extracellular Polymers

Abstract

The lithium-ion battery market is rapidly expanding but lacks recycling for spent lithium-ion battery (SLIB) cathodes, overlooking their potential as valuable raw materials. Herein, we present a novel win–win bioregulation strategy to repurpose SLIB cathodes into dual-functional biocatalysts for oxygen and hydrogen evolution reactions (OER and HER) using Aspergillus niger soluble extracellular polymers. In the recycled SLIB cathode ink, 85% of cobalt has been regenerated as catalysts. Simultaneously, valuable materials such as graphite and cobalt, which have not been regenerated, are separated and stored. Integrating characterization and theoretical calculations reveals that bioregulation enhances the hydrophilicity of 70-Bio-Co/GOs and enables biological nitrogen doping. Compared to the catalyst lacking bioregulation, we observe a 0.27 eV elevation in the d-band center and identify a metallic-like electron distribution around the Fermi level. Consequently, compared with other studies, 70-Bio-Co/GO exhibits a slight superiority in OER (η 10 of 251 mV), HER (η 10 of 110 mV), and overall water splitting (25 mA cm –2 with a potential of 1.641 V) performance, along with stability (98 h). Overall, we investigated the potential of bioregulation technology for regenerating SLIBs.