General Synthesis of 2D Mesoporous Multimetal Spinel Supracrystals for High‐Efficiency Electrochemical Applications

Two‐dimensional (2D) mesoporous metal oxide crystals that integrate atomic‐level single crystallinity with ordered mesoporosity represent a promising but rarely realized class of materials, particularly in multicomponent systems. Here, we report a universal strategy for synthesizing freestanding 2D mesoporous spinel supracrystals with tunable compositions, spanning from unary to multinary spinel oxide systems. This approach decouples crystalline framework formation from mesopore generation, combining emulsion‐mediated, on‐surface crystallization of 2D nanocrystal superlattices with thermally‐induced collective nanocrystal reorientation and facet‐selective epitaxial fusion. Concurrent surface reconstruction exposes {110} facets along nanocrystal edges, which define the internal surfaces of vertically aligned mesopores. As a proof of concept, 2D mesoporous FeMnCoO supracrystals are employed as functional interlayers in lithium–sulfur (Li–S) batteries. These interlayers demonstrate strong polysulfide adsorption, accelerated redox kinetics, and enhanced Li + ion transport, enabled by their multimetal‐induced electronic modulation, facet‐specific catalytic activity, and 2D mesoporous architecture. As a result, Li–S cells equipped with FeMnCoO‐modified separators deliver exceptional electrochemical performance, even under high sulfur loading and lean electrolyte conditions. This work addresses a longstanding challenge in reconciling ordered mesoporosity with crystallographic coherence in mesoporous materials, establishing a molecularly modular approach for synthesizing 2D mesoporous spinel crystals with programmable compositions and facet‐engineered functionality.