Ion‐Electron Coupling Strategy Induced by Interface Electric Field Enables High‐Performance LiFePO ₄ From Spent Cathode

Abstract

ABSTRACT The direct regeneration of spent LiFePO 4 (LFP) is primarily constrained by the high energy barriers for concurrent Li + and electron transport, which has rarely been systematically addressed. Herein, an ion‐electron coupling (IEC) strategy is proposed, driven by an interfacial electric field (IEF), to achieve coordinated Li + and electron flow, thereby overcoming these transport barriers. The strategy of constructing localized boron–carbon (B–C) dipoles clothing on the LFP surface establishes a work function ( W F ) gradient with the exterior lower than the interior. This unique gradient drives spontaneous electron flow from the C@B to the LFP to form a directional IEF that simultaneously establishes efficient Li + transport pathways. This synergistic process significantly lowers the energy barriers for both carriers, ensuring ample Li + and electron supply for effective regeneration. Moreover, the IEF is maintained in the regenerated LFP, which also ensures rapid Li + and electron transport and leads to the excellent electrochemical performance of the regenerated LFP, with an outstanding rate capacity of 111.4 mAh g − 1 at 10 C, a capacity retention of 86.6% after 1000 cycles at 1 C. This work provides a novel and universal strategy to upgrade the LFP cathode from spent lithium‐ion batteries.