High-performance sodium-ion anode based on stable phosphorus–carbon bond in black phosphorus−hard carbon nanocomposite.

Black phosphorus (BP) is a promising material with a high theoretical specific capacity and high carrier mobility. Nevertheless, the anode volume expansion of BP during charging and discharging represents a significant obstacle to its further development in sodium-ion batteries (SIBs) which reduces their properties in terms of specific capacity and cycling stability. To solve the problem, a series of BP and hard carbon (BP-HC) composites are prepared with different mass ratios (7:3, 5:5, and 4:6) by a simple ball milling method. Various characterization techniques are used to analyze the microstructures and binding conformations of the materials. It is found that a strong interaction between BP and HC through the formation of phosphorus-carbon (P–C) and phosphorus-oxygen-carbon (P–O–C) bonds which benefits the electrochemical performance of SIBs. Among the three BP-HC anodes, the BP-HC-46 anode shows the best cycling stability, with a high initial discharge specific capacity of 2448.8 mAh g−1 at a current density of 0.1 A g−1 and a reversible capacity of up to 1842.2 mAh g−1 after 50 cycles with a retention rate of 97.4 % (compared to the second discharge specific capacity of 1890.6 mAh g−1). This study proposes a straightforward method for synthesizing BP-HC anode composites in SIBs. [Display omitted] • BP-HC nanocomposites were fabricated by a straightforward ball milling process. • Strong P–C and P–O–C bonds are formed between BP-HC Nanocomposite. • The ratio of BP-HC composites with the best electrochemical performance is 4:6. • The anode shows good cyclic stability and an initial capacity of 2448.8 mAh g−1. • The fast Na + diffusion kinetics and capacitance-dominated behavior were elucidated. [ABSTRACT FROM AUTHOR]