Metalation of porphyrin units in a porous organic polymer stabilizing its anodic cycling performance in lithium-ion battery

Organic materials have attracted tremendous interest as electrodes materials for lithium-ion battery, however, they still suffer from intractable problems including inherent low electronic conductivity, poor cycling stability and high solubility in electrolyte etc. Herein, a porphyrin-based porous organic polymer (POP) is employed to serve as anode material by virtue of its good insolubility, unique π-π interaction and abundant active sites. The POP electrode exhibits a high specific capacity of 584 mAh g⁻¹ at 100 mA g⁻¹ originated from fast redox activity while unfortunately undergoes a severe capacity fading during long-term cycles. It is found that the metalation of porphyrin moiety in POP by Ni²⁺ (Ni-POP) enables an excellent cycling stability of 380 mAh g⁻¹ with a capacity retention of 99 % for 500 cycles. We revealed that porphyrin unit is decomposed from the cleavage of the C-N/C=N bonds in porphyrin units, while Ni coordination stabilizes porphyrin units during fast redox process as affirmed by ex situ X-ray photoelectron spectroscopy. The easy fabrication, low-cost and excellent performance make Ni-POP great potential as anode material for lithium-ion battery.