In-situ synthesis of Cu-based conductive metal organic frameworks on graphene layers for high-performance lithium and potassium ion batteries

To meet the increasing energy demands, developing new materials is necessary for high-performance rechargeable batteries. Using hexahydroxytriphenylene (HHTP) as ligand, a novel Cu-based conductive metal organic framework composite (Cu-HHTP/G) was synthesized by adding graphene (G) in situ during the synthesis process. The introduction of graphene could effectively reduce the stacking of Cu-HHTP and induce the formation of a continuous 2D conductive network which could efficiently facilitate the charge transfer. The higher porosity and more exposed surface of Cu-HHTP/G compared with pristine Cu-HHTP resulted in better electrochemical performances. The ex-situ XPS analysis confirmed that both copper ions and aromatic rings of the ligand participated in the lithium storage mechanism. When tested as anode of lithium-ion and potassium-ion batteries (LIBs and PIBs) for the first time, Cu-HHTP/G composite provided large reversible capacities of 1086/226 mAh g−1 for LIBs/PIBs at 0.1 C after 300 cycles. In addition, it still exhibited the specific capacities of 621/165 mAh g−1 for LIBs/PIBs at 1 C after 500 cycles. The Cu-HHTP/G composite represented a promising anode of next-generation LIBs and PIBs.