Long-Life Regenerated LiFePO 4 from Spent Cathode by Elevating the d-Band Center of Fe.

A large amount of spent LiFePO 4 (LFP) are produced in recent years because it is one of the most widely used cathode materials for electric vehicles. The traditional hydrometallurgical and pyrometallurgical recycling methods are doubted because of economic and environmental benefits, direct regeneration method is considered a promising way to recycle spent LFP. However, the performance of regenerated LFP by the direct recycling method is generally not ideal due to the migration of iron (Fe) ions during cycling and irreversible phase transition caused by sluggish lithium ion (Li + ) diffusion. The key to addressing the challenge is to immobilize Fe atoms in the lattice and improve the Li + migration capability during cycling. Here, we effectively regenerated spent LFP by using environment-friendly ethanol and promoted its cycling stability by elevating the d-band center of Fe atoms via constructing a heterogeneous interface between LFP and nitrogen-doped carbon. The Fe-O bonding is strengthened and the migration of Fe ions during cycling is suppressed due to the elevated d-band center. The diffusion kinetics of Li + in regenerated LFP were improved, leading to an excellent reversibility of the phase transition. Therefore, the cell with a regenerated LFP cathode exhibits an ultra-stable cycling performance at a high rate of 10 C with ∼80% capacity retention after 1000 cycles. This article is protected by copyright. All rights reserved.