Internal Al/Al ₂ O ₃ Potential Drop Impacted by External Al ₂ O ₃ /Electrolyte Interaction to Unlock Al Corrosion in Lithium Metal Batteries

ABSTRACT High‐voltage lithium‐metal batteries are pivotal for increasing energy density but suffer from aluminum (Al) current collector corrosion. While the native Al 2 O 3 layer provides thermodynamic stability, corrosion persists through electric‐field‐driven Al 3+ migration. Guided by P. Marcus theory, we identify that the total potential drop across the Al/Al 2 O 3 /electrolyte system is partitioned between two distinct interfaces, where the internal Al/Al 2 O 3 potential drop generates a localized electric field that serves as the fundamental kinetic driver for Al 3+ egress. Departing from conventional strategies focused on anion‐induced chemical passivation, we establish an interfacial potential modulation framework and report a cascade effect where intensifying specific anion adsorption at the external Al 2 O 3 /electrolyte interface increases the external potential drop, which inherently reduces the internal potential drop. This potential redistribution weakens the internal electric field and elevates the energy barrier for outward Al 3+ transport. By introducing NO 3 − as an electric‐field‐responsive anion to optimize this distribution, we enable Li||NCM811 cells to maintain stable capacity at 4.5 V for over 180 cycles. These findings establish a versatile theoretical framework for stabilizing multiphase interfaces in high‐voltage energy storage systems.