Facile synthesis of CoMn2O4@CoMn2S4 core-shell nanoclusters@nanosheets as advanced hybrid capacitor electrode materials

Abstract

In this work, a novel CoMn2O4@CoMn2S4 core-shell nanocluster@nanosheet was successfully grown onto Ni foam via a hydrothermal reaction, which omitted the addition of a binder and conductive additive and the need for a complicated electrode preparation process. CoMn2S4 nanosheets as "shells" were found to be uniformly distributed on the surface of CoMn2O4 nanoclusters as "cores" to form a typical core-shell structure. These structures possess a high specific surface area and abundant active sites, which not only shorten the transmission path for electrons and ions, but also prevent collapse of the structure, thus improving its cycling stability. The specific capacity of CoMn2O4@CoMn2S4 is 1542.0 C g−1 at a current density of 1 A g−1, which is 3.1 times higher than that obtained for CoMn2O4. Moreover, CoMn2O4@CoMn2S4 shows excellent electrochemical cycling performance, and the specific capacity retention rate for CoMn2O4@CoMn2S4 reaches 95.81% after 5000 cycles at a current density of 20 A g−1. The specific energy of the CoMn2O4@CoMn2S4 reaches 44.30 Wh kg−1 at a specific power of 774.98 W kg−1. Therefore, the CoMn2O4@CoMn2S4//AC device shows excellent practical application capability.