Multilayer Superlattices of Monolayer Mesoporous Carbon Framework‐Intercalated MXene for Efficient Capacitive Energy Storage

Abstract Incorporating conductive and porous components as pillaring materials into the interlayers of two‐dimensional (2D) materials offers a solution to the restacking issue and enables the creation of multifunctional hetero‐superstructures. Here, multilayer MXene superlattices intercalated with monolayer mesoporous carbon frameworks (MMCFs) are synthesized by colloidal co‐assembly of MXene Ti 3 C 2 T x nanosheets and Fe 3 O 4 nanoparticles. The intercalated MMCFs not only increase interlayer spacing and create porous channels for fast mass transport but also act as conductive pillars to facilitate electron transfer along the z ‐direction. These unique structural features allow for the full utilization of unilamellar MXene, making the resulting Ti 3 C 2 T x /MMCF superlattices particularly suitable for capacitive energy storage in organic electrolytes containing bulky ions. As a demonstration, supercapacitors made from Ti 3 C 2 T x /MMCFs exhibit a volumetric capacitance of 317 F cm −3 in a tetraethylammonium tetrafluoroborate/propylene carbonate electrolyte. Furthermore, on‐chip micro‐supercapacitors (MSCs) fabricated from Ti 3 C 2 T x /MMCFs, using the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate as an electrolyte, achieve an areal energy density of 0.10 mWh cm −2 , surpassing that of most state‐of‐the‐art MXene‐based MSCs developed to date. This study not only highlights the significant potential of Ti 3 C 2 T x /MMCFs for efficient capacitive energy storage in organic electrolytes but also introduces a new method for synthesizing 2D porous hetero‐superstructures for various applications.