Conformal Reconstruction and Dual‐Vacancy Engineering Breaks Kinetics Limitations for Energetic Aqueous Dual‐Cation Storage

Efficient aqueous energy storage with non‐metallic ions is highly desired but challenged by achieving kinetically favorable surface/interface storage chemistry. Herein, by refining the surface proton environment, layered double hydroxides (LDHs) with hydrogen‐aluminum dual vacancies and 3D diffusion channels are demonstrated upon conformal surface reconstruction. An energetic NH4+/H+ dual‐ion co‐intercalation chemistry is enabled, leading to a remarkable gravimetric specific capacity of up to 604 mAh g‐1 and long‐cycle stability. Combining in‐situ Raman spectroscopy and in‐situ electrochemical quartz crystal microbalance (EQCM) techniques, we reveal and visualize the conformal reconstruction process and the reversible dual‐cation storage mechanism. Density functional theory (DFT) calculation shows that the dual‐vacancy coupling helps the dissolution of inert Al from LDH for enriching active sites. At the same time, the residual Al shows the pining effect on the [MnO6] octahedron to restrain the Jahn‐Teller distortion. The manganese sites adjacent to Al vacancies promote the adsorption of NH4+/H+ and the H vacancies facilitate the adsorption of NH4+, responsible for an optimal dual‐cation storage chemistry. This work demonstrates how the dual vacancies emerge to modulate the carrier migration and thereby the capacity, providing a viable solution of surface/interface optimization for efficient aqueous energy storage.