CNTs/Gr composite sandwich layered rare earth phthalocyanines MPcs (M = Yb, La) used as improved energy storage behaviors for lithium-ion batteries

Abstract

To address the problem of aggregation and low electrical conductivity of rare earth phthalocyanines MPc (M = Yb, La), four composites are obtained by applying a physical method to combine two rare earth phthalocyanines with Gr/CNTs. These composites of rare earth phthalocyanines with Gr/CNTs effectively reduce the aggregation of phthalocyanine conjugated units and enhance the electrical conductivity. The electrochemical testing exhibits that the YbPc/CNTs electrode delivers a specific capacity of 1447 mAh/g after 275 cycles at a current density of 100 mA/g, demonstrating a capacity retention of 157.5 %. Similarly, the primitive specific capacity of LaPc/CNTs electrode is increasing from 515 mAh/g to 753 mAh/g at 100 mA/g after 400 cycles. Likewise, YbPc/Gr and LaPc/Gr electrodes have specific capacity of 912 mAh/g and 667 mAh/g after 450 cycles and 356 cycles, revealing capacity retention of 152 % and 74 %. It can be noted that compounding with Gr/CNTs can successfully solve the problems of a few exposures of redox-active sites caused by the aggregation of phthalocyanine conjugate units and poor rate performance owing to the sluggish ion/electrons transport of phthalocyanine, which furnishes a promising perspective for practical research and application of new organic anode materials in the field of superior electrochemical performance lithium-ion batteries.