Regulating Cu-F bonding force with cobalt phthalocyanine to boost the reversibility of CuF2 for endurable lithium-ion storage within moderate voltage-cutoff window.

The CuF 2 @CoPPc lamellar hybrid was prepared by the recrystallization of CoPPc on the surface of CuF 2. This configuration can efficiently prevent CuF 2 from contacting directly with electrolyte and improve the reaction activity by weakening the bonding strength of Cu-F. CoPPc can catalyze the invertibility and surface reaction of CuF 2 , resulting in long cyclability, high capacity and high reversibility. [Display omitted] • A new strategy of tailoring the intrinsic Cu-F bond strength of CuF 2 is introduced to improve its durable reversibility. • As a catalyst, CoPPc enhances and improves the reversibility and surface reaction of CuF 2. • The synergistic effect of CuF 2 and CoPPc drastically promotes the charge transfer kinetics of the composite. • CuF 2 @CoPPc has long cyclability, high capacity and high reversibility. CuF 2 is a promising candidate of electrode materials for lithium-ion batteries due to its high specific capacity, high power density and environmental friendliness. However, the irreversible phase conversion and sluggish kinetics caused by serious copper dissolution and low conductivity make CuF 2 difficult to achieve long cycling life. A facile strategy to incorporate CoPPc into CuF 2 was proposed firstly to regulate the Cu-F bonding force to realize the high reversibility of CuF 2 for lithium-ion storage. The results of DFT calculation, differential charge density simulation, work function calculation and COHP bond level calculation show that the existence of CoPPc can improve the surface charge distribution of CuF 2 and thus improve the reversibility for durable lithium-ion storage. The cycle life performance of the CuF 2 @CoPPc composite electrode obtained by this method reached staggering 500 cycles and the capacity remained at 594.8 mAh/g. [ABSTRACT FROM AUTHOR]