Saqima-like Co3O4/CNTs secondary microstructures with ultrahigh initial Coulombic efficiency as an anode for lithium ion batteries

Abstract

In this work, Co3O4/CNTs composite with Saqima-like secondary microstructure has been synthesized by heat treatment of CoC2O4/CNTs precursors being obtained through ultrasonication-assisted precipitation method. Through SEM, in the composites, the microstructures are composed of tightly connected nanoparticles (30–50 nm), and abundant spaces exist among nanoparticles, which can relieve the strain produced by volume effect to ensure the stability of integral structure during cycles; CNTs are dispersed in microstructures and bridge between microstructures, which can form a long-range conductive network in the composite. The electrochemical test indicates that the composite shows ultrahigh initial coulombic efficiency (ICE) of 85%, as well as excellent rate performance and cyclic stability. The high ICE is mainly ascribed to the formation of a stable solid electrolyte interphase (SEI) film only on the outer surface of microstructures. This work offers an available and general way to improve the ICE of transitional metal oxide as an anode material for LIB.