Microenvironment‐Regulated Interfacial Reconstruction Enables High‐Performance Direct Regeneration of Spent LiFePO 4 Cathodes

ABSTRACT Driven by the massive deployment of LiFePO 4 (LFP) in energy storage systems, the high‐value direct regeneration of spent LFP (SLFP) has become a critical pathway toward closed‐loop recycling of lithium‐ion batteries. However, direct regeneration technologies are considered challenging because residual surface impurities on SLFP hinder the relithiation process and the low electrical conductivity of regenerated LFP limits rate capability. Herein, we propose a microenvironment regulation strategy in which dicyandiamide (DCD) and lithium orotate (LiOr) synergistically achieve lattice restoration and interfacial reconstruction of SLFP. Mechanistic investigations reveal that the NH 3 ‐rich reducing microenvironment generated from DCD efficiently removes the residual C–F and CO 3 2– species by gas‐phase reactions and suppresses nitrogen loss of LiOr decomposition during regeneration. Under the microenvironment, LiOr serves as a multifunctional relithiation agent, enabling efficient lithium replenishment and in situ nitrogen‐doping (N‐doping) of the carbon layer. As a result, the regenerated LFP achieves a capacity retention of 90.9% after 1000 cycles at 5 C, demonstrating excellent cycling stability and rate performance. Techno‐economic analysis further highlights its advantages over conventional recycling routes, offering a viable pathway for the direct regeneration of SLFP.