Co-N-macrocyclic modified graphene with excellent electrocatalytic activity for lithium-thionyl chloride batteries

A mixture of cobalt phthalocyanine (CoPc) and graphene is thermally decomposed at 800 °C to synthesize a novel catalyst. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) show that the catalyst retains the lamellar structure of graphene. X-ray diffraction (XRD) reveals that the catalyst is no longer composed of CoPc and high-resolution TEM (HRTEM), X-ray photoelectron spectra (XPS) prove that Co and N elements have entered the graphene molecular structure, thus forming a Co-Nx-graphene (Co-Nx-G) catalyst composed of a CoN4-macrocyclic-like structure. This catalyst serves as an excellent catalyst of thionyl chloride (SOCl2) reduction. Cyclic voltammetry and battery discharge tests reveal that Co-Nx-G-800 substantially increases the discharge voltage and capacity of a Li/SOCl2 battery. Moreover, Co-Nx-G-800 exhibits stable catalytic activity during battery storage. Ultraviolet-visible spectroscopy shows that CoPc is soluble in a SOCl2 electrolyte solution, whereas Co-Nx-G-800 is not, this characteristic contributes to the stable catalytic property of Co-Nx-G.