Conjugated cobalt polyphthalocyanine with defective ?-? extended structure for enhanced rechargeable li-oxygen batteries

The urgent demand for high-energy and high-power energy storage devices initiates considerable interest for LiO2 batteries. Considering the catalytic reaction that happened on the cathode, the electrocatalyst plays a key role in deciding the performance of Li-O2 batteries. Herein, a cobalt polyphthalocyanine with defective polymeric layered structure (D-CoPPc) is prepared by an annealing treatment. The macromolecular structure of D-CoPPc overcomes the dissolution of cobalt phthalocyanine (CoPc) therefore guarantying structural stability. Such a distinctive structure provides imperative features for Li-O2 batteries involving the intrinsic high catalytic activity of CoPc unit, high conductivity given by pi-pi extended conjugated skeleton. Moreover, the introduced irregular structural defects are expected to promote the diffusion of oxygen. As a result, Li-O2 battery with D-CoPPc as a catalyst achieves a high specific capacity of 4.0 mA h cm-2 at a current density of 50 mu A cm-2, a remarkable rate capability with the discharge voltage reached at 2.55 V at a current density of 500 mu A cm-2, and a superior cycling stability of more than 1000 h at 20 mu A cm- 2. As such, the presented framework tailoring and defect engineering strategy open new avenues to regulate the catalytic activity for high-performance metal-oxygen batteries.

Automated summary

The cobalt polyphthalocyanine with defective polymeric layered structure (D-CoPPc) prepared by annealing treatment exhibits excellent catalytic activity, high conductivity, and structural stability in Li-O2 batteries, showing potential to improve the specific capacity, rate capability, and cycling stability of the battery.