Construction of hierarchical nanoparticle-assembled magnesium‑nickel‑cobalt oxides@carbon composites nanorods for high-performance supercapacitor

Abstract

Construction of hierarchical nanostructured multimetallic oxides@carbon composite is an effective strategy to develop advanced electrode material for high performance asymmetric supercapacitors. In this paper, we synthesized a series of Mg-Ni-Co oxides@carbon composites via calcination of multimetal-ethylenediamine tetraacetic acid (EDTA) coordination complexes in air. We revealed the different coordination abilities of Mg²⁺, Co²⁺ and Ni²⁺ with EDTA by analyzing the compositions of these composites and pointed out the presence of Ni²⁺ is required for the formation of rod-like structures. More importantly, we found trimetal-EDTA complexes derivatives exhibit better electrochemical performance than the related bimetal-EDTA complexes derivatives due to the synergistic effects of structure and composition. An asymmetric supercapacitor assembled with the optimal trimetal-EDTA complex derivative (NiCo₂O₄/NiO/MgO/C composite) as positive electrode exhibited high energy density (22.1 Wh kg⁻¹ at a power density of 375 W kg⁻¹) and excellent cycling stability (93.8 % after 10,000 cycles). This work provides meaningful insights into the design of high-performance electrode materials derived from metal-EDTA complexes.