NiO/nitrogen-oxygen co-doped carbon nanoflower composites based on covalent organic frameworks for lithium-ion battery anodes

Designing novel NiO/porous carbon nanocomposites is an effective strategy to improve poor conductivity and rapid capacity fading of NiO in lithium-ion batteries (LIBs). Covalent organic frameworks (COFs) are attractive materials for LIBs as they have large specific surface areas, well-ordered structure, and controllable pore size. Here, we designed a COFTpPa nanoflower as templates for the preparation of porous carbon and a carrier for NiO to obtain NiO/nitrogen-oxygen co-doped carbon nanoflower (NiO/NCF) composites. NiO nanostructures have a smaller volume effect, and the coating of carbon nanoflowers can further buffer the volume expansion of NiO nanostructures, which effectively slow down the capacity decay. In addition, the NCF derived from COFTpPa provide a larger specific surface area and more pores, which not only increases the capacity of nanocomposites but also improves the electrical conductivity of the electrodes. When applied to the anode of LIBs, NCF and NiO/NCF exhibit excellent performance (with first-cycle capacities of 1038.2 and 1685.9 mAh g−1, respectively, and high first coulomb efficiencies of 61.5 % and 60.9 %, respectively). The designed NiO/NCF nanocomposites is a promising anode material for LIBs.