Preparation of MOF-derived NiCoP nanocages as anodes for lithium ion batteries

Double metal phosphide (NiCoP) nanocage was synthesized with zeolitic imidazolate framework-67 (ZIF-67) as the template, further acidic etching and precipitation, finally phosphorization treatment with NaH2PO2. The nanocages well inherit the quasi-polyhedron shape of the ZIF-67 templates, and both the outer and inner shell of the nanocage is composed of many interconnected nanosheets with large quantities micro-holes on the surface. The nanosheets cross-link to form unique multi-channel frameworks for both ions and electrons fast-diffusion. Electrochemical measurements demonstrate that the NiCoP electrode, when used as an anode for lithium ion battery, offers a high reversible capacity (622 mAh/g at 100 mA/g), as well as a high rate capacity (373 mAh/g at 1000 mA/g), and good cyclability with a capacity retention of 104 mAh/g after 100 cycles at 1000 mA/g.