Synthesis of NiCoMn ternary metal–organic frameworks with a hollow spherical structure for high-performance asymmetric supercapacitors.

With adequate specific surface area and adjustable pore structure, metal–organic frameworks (MOFs) have raised concerns over super-capacitor development. However, its practical application in supercapacitors was limited by the restricted electroactive sites and poor stability. This paper proposes a simple one-step solvothermal method to synthesize a hollow spherical NiCoMn-MOF. The formed hollow structure is conducive to electrolyte permeation and electron/ion transport. In addition, the as-prepared NiCoMn-MOF exhibit a clear synergy between transition metal ions, which contributes to enhanced electrochemical performance. The advantageous structure and composition make the resulting Ni₃Co₁Mn_0.5-MOF displays a superior specific capacitance of 572 C g⁻¹ (1 A g⁻¹) and excellent cycling stability with 84.05% of the original specific capacitance retained after 5000 charge–discharge cycles. Moreover, an asymmetric supercapacitor assembled with Ni₃Co₁Mn_0.5-MOF and activated carbon demonstrates a good specific capacitance of 188.7 F g⁻¹ at 1 A g⁻¹ and a high energy density of 66.75 Wh kg⁻¹ at a power density of 791.65 W kg⁻¹. This research reveals that the hollow NiCoMn-MOF has great potentials in the application in supercapacitors. [ABSTRACT FROM AUTHOR]