Selective Phosphorization Boosting High-Performance NiO/Ni₂Co₄P₃ Microspheres as Anode Materials for Lithium Ion...

Phosphorization of metal oxides/hydoxides to promote electronic conductivity as a promising strategy has attracted enormous attention for improving the electrochemical properties of anode material in lithium ion batteries. For this article, selective phosphorization from NiCo₂O₄ to NiO/Ni₂Co₄P₃ microspheres was realized as an efficient route to enhance the electrochemical lithium storage properties of bimetal Ni-Co based anode materials. The results show that varying phosphorizaed reagent amount can significantly affect the transformation of crystalline structure from NiCo₂O₄ to intermediate NiO, hybrid NiO/Ni₂Co₄P₃, and, finally, to Ni₂Co₄P₃, during which alterated sphere morphology, shifted surface valance, and enhanced lithium-ion storage behavior are detected. The optimized phosphorization with 1:3 reagent mass ratio can maintain the spherical architecture, hold hybrid crystal structure, and improve the reversibly electrochemical lithium-ion storage properties. A specific capacity of 415 mAh g^-1 is achieved at 100 mA g^-1 specific current and maintains at 106 mAh g^-1 when the specific current increases to 5000 mA g^-1. Even after 200 cycles at 500 mA g^-1, the optimized electrode still delivers 224 mAh g^-1 of specific capacity, exhibiting desirable cycling stability. We believe that understanding of such selective phosphorization can further evoke a particular research enthusiasm for anode materials in lithium ion battery with high performances.