摘要
Cobalt phosphide （COP） nanoparticles which were uniformly embedded in N-doped C nanosheets （CNSs） were fabricated via the simple one-step calcination of a Co-based metal-organic framework （MOF） and red P and exhibited a high capacity, fast kinetics, and a long cycle life. This CoP/CNS composite contained small CoP particles （approximately 11.3 nm） and P-C bonds. When its electrochemical properties were evaluated by testing CoP/Na coin cells, the composite delivered a Na-storage capacity of 598 mAh·g-1 at 0.1 A·g-1 according to the total mass of the composite, which means that the capacity of pure CoP reached 831 mAh·g-1 The composite also exhibited a high rate capability and long-term cyclability （174 mAh·g-1 at 20 A·g-1 and 98.5% capacity retention after 900 cycles at 1 A·g-1）, which are commonly attributed to robust P-C bonding and highly conductive CNSs. When the reaction mechanism of the CoP/CNS composite was investigated, a conversion reaction expressed as CoP ＋ 3Na＋ ＋ 3e＋＋ Co ＋ Na3P was observed. The outstanding Na-storage properties of the CoP/CNS composite may suggest a new strategy for developing high-performance anode materials for Na-ion batteries.
Cobalt phosphide （COP） nanoparticles which were uniformly embedded in N-doped C nanosheets （CNSs） were fabricated via the simple one-step calcination of a Co-based metal-organic framework （MOF） and red P and exhibited a high capacity, fast kinetics, and a long cycle life. This CoP/CNS composite contained small CoP particles （approximately 11.3 nm） and P-C bonds. When its electrochemical properties were evaluated by testing CoP/Na coin cells, the composite delivered a Na-storage capacity of 598 mAh·g-1 at 0.1 A·g-1 according to the total mass of the composite, which means that the capacity of pure CoP reached 831 mAh·g-1 The composite also exhibited a high rate capability and long-term cyclability （174 mAh·g-1 at 20 A·g-1 and 98.5% capacity retention after 900 cycles at 1 A·g-1）, which are commonly attributed to robust P-C bonding and highly conductive CNSs. When the reaction mechanism of the CoP/CNS composite was investigated, a conversion reaction expressed as CoP ＋ 3Na＋ ＋ 3e＋＋ Co ＋ Na3P was observed. The outstanding Na-storage properties of the CoP/CNS composite may suggest a new strategy for developing high-performance anode materials for Na-ion batteries.
