Recycling spent ternary cathodes into multi-heterogeneous Ni4N/Co5.47N/MnO composite catalysts enable efficient oxygen evolution reaction

Fabricating efficient electrocatalysts for water splitting through recycling ternary (LiNi 1-x-y Mn x Co y O 2 ) cathodes of spent lithium-ion batteries (LIBs) is promising and sustainable, however, the relative reasonable phase composition and microstructure still need be explored. Herein, a composite material composed of multi-heterogeneous Ni 4 N/Co 5.47 N/MnO nanoparticles coupled with porous carbon fibers was fabricated through a direct carbothermal reduction process of waste LiNi 0.5 Mn 0.2 Co 0.3 O 2 (NCM523) cathodes material dispersed into nitrogenous spinning precursor. Interestingly, this optimized material obtained at 800 °C (NCM523@CF-800) possesses abundant Ni 4 N/Co 5.47 N/MnO multi-heterostructure, endowing it with multifaceted advantages as electrocatalysts for oxygen evolution reaction (OER). Specifically, the unique structural features of multi-heterostructure promote the transfer of electrons/charges on the interface, and highly enhance the reaction kinetics. Additionally, during OER process, because of the protection of carbon matrix, Ni 4 N/Co 5.47 N/MnO has the mere surface reconstruction and forms the real active oxygen-containing species especial NiOOH. And the maintained core of Ni 4 N/Co 5.47 N/MnO provides high conductivity for the formed active oxygen-containing species. As a result, the optimized NCM523@CF-800 employed as OER electrocatalyst in water electrolysis only require 271 mV to deliver a current density of 10 mA cm −2 in 1 M KOH. Meanwhile, an excellent stability of 140 h can be achieved under high current density of about 160 mA cm −2 . This work may pave the way for the rapid and efficient recycling and utilization of spent battery electrode materials.