Two-dimensional flower-like cobalt-porphyrin MOF/rGO composite anodes for high-performance Li-ion batteries

In this study, a novel flower-like Co-TCPP MOF/rGO composite has been successfully synthesized by combining cobalt meso-tetrakis(4-carboxyphenyl) porphyrin (Co-TCPP MOF) and reduced graphene oxide (rGO) via a simple one-pot solvothermal method. The introduction of rGO not only reduces the stacking of MOF effectively, but also facilitates the formation of a continuous conductive network composed of entangled graphene and Co-TCPP MOF in favor of rapid electron transport. More importantly, the ultrathin lamellar structure of Co-TCPP MOF/rGO composite nanosheets could expose more active sites, reduce the diffusion distance of Li+ to the internal electroactive sites, and improve the overall electrical conductivity of the electrode due to their sufficient contact with carbon. When evaluated as anode materials for lithium-ion batteries, the flower-like Co-TCPP MOF/(15 wt%)rGO composite electrode delivers a specific capacity of 1050 mAh g−1 at 100 mA g−1 after 100 cycles. A specific capacity of 650 mAh g−1 can be remained after 300 cycles even at 1000 mA g−1. The superior performance of the Co-TCPP MOF/(15 wt%)rGO composite electrode could be attributed to the introduction of rGO, which prevents the stacking growth of Co-TCPP MOF crystals along the horizontal direction and improves the electrical conductivity.