Highly effective bifunctional defective cobalt phthalocyanine for photo-involved lithium-oxygen batteries

Abstract

Lithium-oxygen batteries (LOBs) have become efficient energy storage devices. However, the discharge product (Li₂O₂) results in a large overpotential in the charge and discharge process, which hinders the application of LOBs. Herein, carbon nanotube-supported defective polymerized cobalt phthalocyanine composite was prepared by hydrothermal method and used as a cathode in photo-involved LOBs. The introduction of irregular structural defects not only facilitates the diffusion of O₂ and Li⁺ but also accelerates the separation of photoelectrons and holes. Under light irradiation, the discharge potential is promoted to 3.30 V and the charge potential is reduced to 3.40 V at 0.05 mA cm⁻², resulting in a high energy efficiency of 97.1%. Meanwhile, the complete decomposition of sheet Li₂O₂ is realized in the charge process, so that the battery polarization remained unchanged after more than 65 h of cycling. This study provides an effective reference for subsequent application of metal–organic materials in metal-air batteries as a photoelectric-cathode.