Ternary Self-Assembly of Ordered Metal Oxide−Graphene Nanocomposites for Electrochemical Energy Storage

TLDR

Self‑assembly has been widely used to create nanostructured metal oxides and hybrids, yet its application to complex, multiscale, multiphase systems has been limited. The study demonstrates a ternary self‑assembly method that uses graphene as a fundamental building block to construct ordered metal‑oxide/graphene nanocomposites. The method self‑assembles graphene into ordered layered structures, incorporates it into liquid‑crystal‑templated nanoporous networks, and produces flexible, free‑standing films and electrodes. The resulting layered nanocomposites show stable, ordered alternating metal‑oxide/graphene layers, and SnO₂‑graphene films achieve near‑theoretical Li‑ion energy density with minimal charge‑discharge degradation.

Abstract

Surfactant or polymer directed self-assembly has been widely investigated to prepare nanostructured metal oxides, semiconductors, and polymers, but this approach is mostly limited to two-phase materials, organic/inorganic hybrids, and nanoparticle or polymer-based nanocomposites. Self-assembled nanostructures from more complex, multiscale, and multiphase building blocks have been investigated with limited success. Here, we demonstrate a ternary self-assembly approach using graphene as fundamental building blocks to construct ordered metal oxide−graphene nanocomposites. A new class of layered nanocomposites is formed containing stable, ordered alternating layers of nanocrystalline metal oxides with graphene or graphene stacks. Alternatively, the graphene or graphene stacks can be incorporated into liquid-crystal-templated nanoporous structures to form high surface area, conductive networks. The self-assembly method can also be used to fabricate free-standing, flexible metal oxide−graphene nanocomposite films and electrodes. We have investigated the Li-ion insertion properties of the self-assembled electrodes for energy storage and show that the SnO2−graphene nanocomposite films can achieve near theoretical specific energy density without significant charge/discharge degradation.