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

Abstract

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.