Single atom site conjugated copper polyphthalocyanine assisted carbon nanotubes as cathode for reversible Li-CO₂ batteries

Recently, Li-CO₂ battery has gradually become a research hotspot due to its high discharge capacity, energy density and environmental benefits. However, it has been an important problem for researchers because of its slow decomposition kinetics and difficult to generalize to practical application. Herein, we prepared copper polyphthalocyanine-carbon nanotubes composites (CuPPc-CNTs) by solvothermal in-situ polymerization of copper phthalocyanine on the surface of carbon nanotubes as cathode for reversible Li-CO₂ batteries, which exhibits a high discharge capacity of 18,652.7 mAh·g^–1 at current density of 100 mA·g^–1, 1.64 V polarization at 1,000 mA·g^–1, and a stable cycles number of 160 is close to 1,630 h of charge-discharge process at 200 mA·g^–1. Copper polyphthalocyanine has highly efficient copper single-atom catalytic sites with excellent CO₂ adsorption and activation, while carbon nanotubes provide a conductive network. The synergistic effect of the two compounds enables it to have excellent catalytic activity. The density functional theory (DFT) calculation proved that the addition of copper polyphthalocyanine significantly improved the CO₂ adsorption and activation process. This study provides an opportunity for the research of covalent organic polymers (COPs) single-atom catalyst in Li-CO₂ battery field.