MOFs as template-derived NiCoMn-LDH with a hollow polyhedron structure for high-performance supercapacitors

Abstract

Metal element selection and reasonable design of material morphology are essential to ensure the improvement of supercapacitor electrochemical performance. In this work, based on the cobalt salts and manganese salts in the bimetallic organic framework with different molar ratios, a ternary layered double hydroxide electrode material with a hollow polyhedral structure was made by Ni2+ etching the bimetallic organic framework to assess its suitability for use in a supercapacitor. When the molar ratio of Co/Mn is 3:1, NiCoMn-LDH 3:1 has a maximum specific capacity of 227.8 mAh g−1 at the current density of 1 A g−1 and a capacity retention rate after 1500 cycles is 83.9% at the large current density of 10 A g−1. Additionally, an asymmetric supercapacitor was assembled with NiCoMn LDH 3:1 as the positive electrode and AC as the negative electrode. The prepared NiCoMn-LDH 3:1//AC ASC device showed a high energy density of 64.3 Wh kg−1 at 799.9 W kg−1. Meanwhile, NiCoMn-LDH 3:1//AC ASC devices have excellent cycle stability, with a capacitance retention rate of 85.1% of the initial capacity after 5000 cycles at a high current density of 10 A g−1. This work provides a new idea for the development of supercapacitor materials.