In-situ synthesis of heteroatom-doped hard carbon for sodium-ion batteries: Dual benefits for green energy and environment.

Heteroatom-doped carbon has been widely investigated as anode materials for sodium-ion batteries (SIBs). However, simplifying the preparation process and precisely controlling their microstructure to achieve excellent Na storage performance remain significant challenges. Therefore, in this study, high-performance N, P co-doped Na storage carbon anode electrode materials were prepared by one-step carbonization using N, P-rich Eichhornia crassipes (EC) as raw materials and systematically tested for their Na storage performance. The doping levels of N and P atoms as well as the spatial structure of the carbon material were adjusted by changing the carbonization temperature during the pyrolysis process. Among them, the anode material corresponding to 1300 °C (EC-PN1300) showed an excellent Na storage capacity of 336 ± 4 mAh g (50 mA g) and excellent cycling stability (99.8 % retention after 2000 cycles). In addition, the Na storage mechanism of EC-PN1300 was systematically analyzed using galvanostatic intermittent titration (GITT), ex-situ XPS and in-situ Raman spectroscopy, providing accurate research directions for developing carbon anode electrode materials with superior electrochemical performance. This study not only provides some insights into the preparation of carbon anode materials in alkali metal batteries and the development of carbon materials in other fields, but also realizes the interaction between environmental protection and new energy development.