Metal-organic framework (MOF) templated hierarchical Al-doped CoxP @ graphene composite: A promising solid-state asymmetric supercapacitor with PANI derived carbon nanorods

Abstract

Metal phosphides are counted as smart electrodes for the supercapacitor field due to their fascinated capacity and conductive features. However, these materials are still suffering from lower conductivity, and significant changes in volume while cycling restricting their potential usage as cathode for such technology. In this study, a novel strategy was primarily established for building hierarchical Al-doped CoxP sheets on graphene as 2D on 2D nanoarchitecture with outstanding electrochemical properties. The hierarchical structure was formed through a cost-effective, and scalable hydrothermal method from a metal-organic framework followed by an efficient phosphorization step. Impressively, the graphene incorporation and Al doping besides morphology merit could largely improve the electrochemical properties of cobalt phosphide. Thus, the new material recorded an outstanding specific capacity as 312.3 mAh/g at an adjusted current density of 1 A/g which is relatively higher compared with the bare Al-CoxP with considerable capacitance retention of 87 % (at 40 A/g). Furthermore, the diffusion-controlled, and capacitive currents were differentiated using standard numerical packages in Python. Motivally, a solid-state asymmetric supercapacitor of Al-CoxP @ rGO//PCNRs was designed to give an ultrahigh energy density of 77.3 Wh/kg at a tuned power density of 1050.5 W/kg with remarkable cycling stability (90 % retention after 10,000 cycles).