Upcycling Spent Cathodes from Li–Ion Batteries into a High-Entropy Alloy Catalyst with Reverse Electron Transfer for Li–O2 Batteries

Traditional recovery of valuable metals from spent ternary lithium-ion batteries concentrates on complicated pyrometallurgy and hydrometallurgy routes. Direct reutilization of these valuable used metals to catalyze Li-O2 batteries is highly appealing yet remains a significant challenge. Here, we report a general synthesis of ultrafine αNiCoMn (α = Pt, Ir, Ru) high-entropy alloy (HEA) nanoparticles anchored on a nitrogen-doped carbon (N-C) support through a facile one-step Joule heating, which serves as a high-efficiency catalyst for Li-O2 batteries. Solution alloying of recycled NiCoMn with Pt group metals facilitates catalytic efficiency through 3d-5d electronic interactions and the high-entropy assembly effect. Both experimental and calculation results reveal that, driven by rapid, nonequilibrium thermal shock, electron transfer defies conventional expectations, where the electrons are inclined to transfer from the higher electronegative Pt to the surrounding NiCoMn atoms. This interesting reverse local charge redistribution and orbital hybridization endow Pt with an elevated d-band center and an optimized electronic structure. The induced high-entropy coordination effects further generate highly active catalysis surfaces, favoring the adsorption of LiO2 intermediates and facilitating rapid decomposition kinetics of nanoscale Li2O2 products. These advantages endow Pt HEA@N-C with superior bifunctional catalytic activity, achieving an ultralow polarization of 0.27 V and a significantly enhanced cycling life of 240 cycles. We anticipate that this work will provide further insights into upcycling spent valuable metals for constructing efficient HEA electrocatalysts.