Sodium Quasi‐Intercalation in Black P for Superior Sodium‐Ion Battery Anodes

Abstract Herein, a Na quasi‐intercalation concept in black P is developed in order to achieve superior P‐based Na‐ion battery (NIB) anodes. Firstly, black P with a puckered layer structure is synthesized via a simple solid‐state reaction using commercially available red P. Additionally, an amorphous carbon modified black P nanocomposite (black P@C) is prepared to optimize its electrochemical Na reversibility. Furthermore, the Na reaction pathways of black P are demonstrated using various ex situ analytical tools. During sodiation/desodiation, black P undergoes the two‐step reactions of sequential quasi‐intercalation of NaP formation (at 0.25 V) and conversion of Na₃P formation (at 0 V). Interestingly, black P@C shows poor cycling performance when using the conversion reaction, but it shows superior performance when using the quasi‐intercalation reaction between black P and NaP. Therefore, we anticipate that the Na quasi‐intercalation in black P@C will lead to high‐performance NIB anodes.