Multimetal–Ligand Synergy in Metal–Organic Frameworks: Unleashing High-Performance Supercapacitor Electrodes

With the rapid depletion of fossil fuels, the development of efficient energy storage devices is of great research significance to solving the energy storage problem. In this article, a solvothermal synthesis process of bimetallic and trimetallic MOF composites was investigated to improve their electrochemical properties by modulating the synergistic effect of metal ions and organic ligands in order to effectively solve the problems of poor conductivity and stability of the materials. The effects of temperature, time, nickel–manganese ratio, metal-to-organic ratio, and ammonia dosage on the structural and electrochemical properties of NiMn-MOF materials were investigated, and the maximum specific capacity of NiMn-MOF materials under optimal conditions was 972 C g–1 at a current density of 1 A g–1. The electrochemical performance of NiMn-MOF//AC, an asymmetric supercapacitor assembled with NiMn-MOF and activated carbon (AC), was explored, and it still showed excellent long-term stability after 5000 consecutive charge/discharge cycles. The NiMn-MOF materials were explored to be synthesized by doping Co ions into the NiMn-MOF materials, which had a unique coral reef structure that can provide abundant void channels to reduce the internal resistance of the material. Finally, the assembled asymmetric supercapacitor NiCoMn-MOF//AC not only has higher energy density and power density than NiMn-MOF//AC but also maintains 93.27% of its initial capacity after 5000 charge–discharge cycles at a current density of 5 A g–1. In this study, through the synergistic effect of polymetallic and organic ligands, not only excellent morphological structures are prepared but also the problems of poor electrical conductivity and insufficient stability can be effectively solved, which is expected to help the energy storage industry to improve the electrochemical performance of energy storage devices.