Tailoring Inner Helmholtz Layer via the Lewis Acid–Base Theory Endow an Elastic SEI for Dendrites‐Free Lithium Metal Anode

Abstract The complex reaction at the electrode‐electrolyte interface in Lithium metal batteries (LMBs) leads to difficulties in precisely modulating the solid electrolyte interphase (SEI) composition. However, the composition and chemical coordination of compounds in the inner Helmholtz plane (IHP) play a crucial role in the evolution of SEI components. Therefore, an interface for cation‐anion co‐enrichment in IHP is engineered by fabricating a Lewis amphoteric V ₂ C T _x ‐Cu ( T _x : ‐O/‐OH/‐F) substrate. V ₂ C T _x ‐Cu is elaborately designed to coordinate with solutes in the electrolyte via Lewis acid–base interactions (Cu ²⁺ ‐TFSI ^– and T _x ^– ‐Li ⁺ ), and increases the anion concentration in the IHP and guides 2D Li deposition behavior along T _x , which promotes the formation of an elastic LiF‐dominated SEI and achieves uniform deposition of Li. Under the synergistic effect of the dual mechanism, dendrite‐free Li deposition/ stripping is achieved even at 8 mA cm ^{− 2} and 24 mAh cm ^{− 2} , facilitating high capacity retention of LMBs with low N/P ratios. The LiFePO ₄ based anode‐free Li metal batteries with a commercial level aeral capacity (4.1 mAh cm ⁻² ) enable stable operation. This work highlights the critical role of interfacial composition and provides valuable insights into the optimization of the IHP through electrode interfacial charge engineering.