Metal Phosphide-Embedded Phosphorus-Based Nanocomposite Anode Materials for Rechargeable Batteries

Abstract

The development of high-performance rechargeable batteries including advanced lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) has been accelerated due to the rapid growth of electric vehicles and stationary large-scale energy storage systems. As one of promising alloying-based anode candidates, elemental phosphorus has attracted much attention among researchers because of its significantly high theoretical specific capacity of 2595 mA h g-1 in both LIBs and SIBs, low-cost, and environmental benignity. However, there are shortcomings such as the large volume change during alloying/dealloying reactions and low conductivity (10-14 S cm-1) of phosphorus, which results in poor cycle performance and slow electrode kinetics. Most approaches aiming at the development of phosphorus-based anode materials have focused on overcoming these difficulties through the utilization of composite structure with nanoscale carbonaceous materials as conductive buffer matrices. While these composites have shown improved cycle and rate performance of phosphorus, they suffer from low initial charge/discharge efficiency and low energy density due to the high carbon content in the structure. In this work, phosphorus-based nanocomposites containing both metal phosphide structure-reinforcing buffer and carbon network have been synthesized by a simple mechanical ball milling method. Morphological characterization shows that metal phosphide particles are well-mixed with phosphorus and further dispersed in carbon matrix. The resultant phosphorus-based nanocomposites exhibit a significantly improved electrochemical performance compared with amorphous red phosphorus, with a high initial Coulombic efficiency of over 80% in both LIB and SIB systems. Combined structural and electrochemical investigation demostrates that the performance improvement is mainly attributed to the presence of conductive phosphide inclusions that mitigates structural degradation and offers high conductivity.