A Partially Stripped Succinonitrile Shield Rendering Air‐Stable Li ₅ FeO ₄ Prelithiation Agent for Dendrite‐Free and Long‐Lifespan Lithium‐Ion Batteries

ABSTRACT Li ₅ FeO ₄ (LFO) is one of the promising prelithiation additives due to its high theoretical capacity (>867 mA h g ⁻¹ ) and facile synthesis. Nevertheless, its practical applicability is grossly compromised by its high air sensitivity. Succinonitrile (SN) is an expected coating material with excellent air stability, high ionic conductivity, and a wide electrochemical window. Herein, a rationally designed SN layer is proposed to evenly coat LFO particles (LFO@SN) through a facile wet‐chemical process. On the one hand, SN effectively suppresses the spontaneous alkalization reaction on the surface of LFO under ambient environment, thereby achieving a high initial charge capacity of 623.8 mA h g ⁻¹ after air exposure (1 h, 25°C, 60%RH). On the other hand, SN partially dissolves in electrolyte and promotes the formation of a Li ₃ N‐containing solid electrolyte interphase, while the residual part acts as a harmful Fe ion adsorbent to prevent its dissolution. Impressively, the LiFePO ₄ ||graphite full cells with LFO@SN additive deliver a remarkable discharge capacity of 167.4 mA h g ⁻¹ and superior capacity retention of 97.3% after 200 cycles. This work provides a simple and feasible strategy to fabricate air‐stable prethiation additives with ultra‐high lithium compensation capacity and interface stabilization ability for advanced lithium‐ion batteries.