High-Performance Asymmetric Supercapacitors Based on Monodisperse CuO@C Polyhedron Nanocomposites

Abstract

Herein, CuO nanocrystals spatially embedded inside carbon polyhedron (CuO@C) derived via morphology-preserved transformation of metal-organic frameworks (MOFs) are utilized for high-performance asymmetric supercapacitors (SCs). Using a conventional MOF (several micrometers in size), pore-filling with polymer inside MOF (polymer@MOF) via vapor-phase polymerization (VPP) process was achieved that amount of polymer used for VPP can be readily adjusted to control the carbon content of CuO@C after thermolysis and subsequent oxidation processes. When monodisperse and nano-sized MOF is used for CuO@C (denoted as nCuO@C_1), it presents superior electrochemical performance because monodispersity and smaller size reduce interfacial resistance and promote mass-transport property, respectively. Asymmetric SC of nCuO@C_1 with carbon sphere (CS) as a counter electrode presents excellent energy density of 55.47 Wh/kg and long-term stability of 88.7% at 5000 cycles, comparable to the best MO-based asymmetric SCs derived from MOFs.