Synthesis and characteristic of the ternary composite electrode material PTCDA/CNT@MPC and its electrochemical performance in sodium ion battery

Abstract

A three-dimensional composite carbon material ([email protected]) showing coaxial cable-like structure was prepared by carbon nanotubes (CNTs) and glucose through hydrothermal method. The ternary composite (PTCDA/[email protected]) was synthesized by coating a layer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecules on the surface of [email protected] composite carbon material. The sodium ion battery was assembled using the ternary composite as the positive electrode material, and sodium metal as the negative electrode. The results show that the electrochemical performance of PTCDA/[email protected] composite is much better than that of pure PTCDA. The first discharge capacity is 131.2 mAh g−1 as the current density is 0.1 A g−1, which is close to its theoretical specific capacity of 135 mAh g−1. In particular, the battery shows better discharge properties at higher discharge current rate. When the current density reaches 10 A g−1, the PTCDA/[email protected] electrode material is still able to attain a superior capacity of 90.1 mAh g−1. This is due to the higher conductivity of [email protected] composite carbon material, which not only enhances the conductivity of PTCDA, but also increases the transport channel of ions, so as to increase the adsorption of sodium ions into the composite positive electrode. Therefore, the reversible capacity and cycle life of the composite electrode are significantly improved, which exhibit the excellent intercalation and de-intercalation performance for sodium ions and the charge-discharge rate performance.