3d Nitrogen Doped Bimetallic Phosphate Superstructure for Enhanced Electrochemical Energy Storage

Abstract

Phosphates have sparked significant interest as a promising candidate for supercapacitors’ cathode on account of their large channels, superior conductivity, and charge storage capacity. Currently, nitrogen doping is widely employed to achieve customized properties of phosphates. Notably, the construction of bimetallic compounds will remarkably promote redox reactions and improve the cycle stability of the electrode through synergistic effects between the metals. Furthermore, compared to crystalline phases, amorphous materials have the potential to achieve increased specific capacity and cycle stability because of numerous active sites for redox reactions and higher strength. In this work, we propose a nitrogen-doped bimetallic phosphate Co0.5Ni0.5-NPO·nH2O, which is converted to amorphous state (A-Co0.5Ni0.5-NPO) through the calcination process in an oxygen atmosphere. A-Co0.5Ni0.5-NPO electrode achieves a high specific capacity (971.84 F g-1 at 0.5 A g-1) and outstanding rate capability. Furthermore, A-Co0.5Ni0.5-NPO//AC asymmetric supercapacitor (ASC) device with a high specific capacity (328 F g-1) and outstanding cycle stability (86.51% retention after 3000 cycles at 3 A g-1) is constructed. The research provide valuable insights for developing bimetallic phosphates as desirable electrode materials for enhanced energy storage systems.

Keywords: supercapacitor, bimetal, phosphate, superstructure, electrochemical energy storage