Molecular Ligand-Mediated Assembly of Multicomponent Nanosheet Superlattices for Compact Capacitive Energy Storage

Abstract

Inspired by the self-assembly of nanoparticle superlattices, we report a general method that exploits long-chain molecular ligands to induce ordered assembly of colloidal nanosheets (NSs), resulting in 2D laminate superlattices with high packing density. Co-assembly of two types of NSs further enables 2D/2D heterostructured superlattices. As a proof of concept, co-assembly of Ti3C2Tx and graphene oxide (GO) NSs followed by thermal annealing leads to MXene-rGO superlattices with tunable microstructures, which exhibit significantly higher capacitance than their filtrated counterparts, delivering an ultrahigh volumetric capacitance of 1443 F cm−3 at 2 mV s−1. Moreover, the as-fabricated binder-free symmetric supercapacitors show a high volumetric energy density of 42.1 Wh L−1, which is among the best reported for MXene-based materials in aqueous electrolytes. This work paves the way toward rational design of 2D material-based superstructures for energy applications.