Waste to Watts: Upcycling Cobalt From Spent Lithium-Ion Batteries Into LaCoO3-Based Heterostructure for High-Performance Supercapacitors

Abstract

The increasing demand for cobalt in energy storage systems, resource scarcity, uneven distribution across territories, and the environmental impacts of its mining pose challenges to sustainable resource use and supply chain security. The current study proposes recovering cobalt from spent lithium-ion batteries for use in supercapacitor devices. A solid-state reaction was proposed to develop a heterostructure mixed-phase architecture, with heterointerfaces that enhance electronic pathways and provide increased active redox sites from lanthanum and cobalt. The synthesized material exhibits synergistic interactions between spinel Co₃O₄ and perovskite LaCoO₃ phases, displaying a hierarchical porous morphology with enhanced electrical conductivity, abundant redox-active sites, and improved charge transfer, ultimately yielding superior electrochemical performance and stability, offering a specific capacitance of 2920.60 F g⁻¹ at 1 A g⁻¹. Additionally, symmetric and asymmetric two-electrode setups were established, achieving maximum power densities of 50 000 W kg⁻¹ and capacitance retention of 51.76% and 13.79% after 10 000 cycles, respectively. The symmetric and asymmetric systems attained maximum energy densities of 880 and 369 Wh kg⁻¹, respectively, and coulombic efficiencies of 97.95% and 100.99% at 1 A g⁻¹, respectively. The work presents a closed-loop approach that combines green recovery of cobalt with the subsequent synthesis of a synergistic multi-phase electrode material, thereby facilitating enhanced electrochemical performance.