Unique FeP@C with polyhedral structure in-situ coated with reduced graphene oxide as an anode material for lithium ion batteries

Iron phosphide as anode material for lithium ion batteries (LIBs) attracts a lot of attention because of large theoretical capacity. Nevertheless, the inherent disadvantages of huge volume expansion and low electrical conductivity inhibit its further application. In this work, FeP@C/reduced graphene oxide (rGO) anode material with unique polyhedral structure was synthesized by a simple solvothermal and low temperature phosphiding method. Metal organic framework MIL-101(Fe) was used as the precursor and anchored on the surface of graphene oxide (GO). The organic ligand of MIL-101(Fe) was transformed to polyhedral carbon skeleton, which combined with GO to form a three-dimensional conductive network that provides efficient channels for electrons and ions, and attenuates volume expansion during the insertion/extraction of lithium ions, and avoids partial pulverization and improves cycle stability. The optimized FeP@C/rGO anode material showed a discharge capacity of 414.7 mAh g−1 at the current density of 8 A g−1, and reached a capacity of 949.7 mAh g−1 after 100 cycles at 0.1 A g−1; even cycled at the current density of 1 A g−1, it provided a capacity of 737.7 mAh g−1 after 450 cycles. In virtue of ingenious microstructure design and structural optimization, FeP@C/rGO exhibited outstanding electrochemical properties in LIBs. [Display omitted] •Metal organic framework MIL-101(Fe) was used as the precursor.•A stable three-dimensional conductive network was formed in the composite.•FeP@C composite was anchored on rGO sheets.•The conductivity of ions and electrons of FeP@C/rGO were obviously improved.•FeP@C/rGO composite showed excellent electrochemical properties.