Porous CoP@N/P co-doped carbon/CNTs nanocubes: In-situ autocatalytic synthesis and excellent performance as the anode for lithium-ion batteries

Abstract

A rational and convenient method was selected to prepare CoP@N/P-co-doped-(C/CNTs) (CoP@N/P-(C/CNTs)) composites with porous nanocubic structure through a pyrolysis-phosphorization strategy derived from ZIF-67. The production of N, P-doped carbon and CNTs formed by in-situ autocatalysis improved the electrical conductivity of the nanocomposite greatly and made the combination of N, P-(C/CNTs) with CoP nanoparticles (NPs) very tightly. The CoP NPs were well encapsulated into the N/P-(C/CNTs) polyhedron. The prepared CoP@N/P-(C/CNTs) had a large specific surface area with 114 m2 g−1 and an average pore diameter of about 10 nm, which were helpful for the efficient diffusion of electrolyte and transfer of ions/electrons. Benefiting from the synergistic effects between highly active CoP NPs and wonderfully conductive N/P-C/CNTs, the CoP@N/P-(C/CNTs) composites exhibited outstanding electrochemical performance. As anodes for lithium-ion batteries (LIBs), the CoP@N/P-(C/CNTs) composites exhibited an excellent initial discharge capacity of 1215 mA h g−1 and reversible capacity of 600 mA h g−1 after 200 cycles at 0.5 A g−1. Even at the high current density of 2 A g−1, it still retained a capacity of 385 mA h g−1. It proved that the autocatalytic formation of CoP@N/P-(C/CNTs) resulted from Co-MOFs is an economical and convenient approach to synthesize electrode materials with high performance for LIBs.