Constructing N, B co-doped carbon nanosheets with pyridine N–B sites for boosting sodium-ion storage

Carbonaceous materials have demonstrated extensive potential as anodes for sodium ion batteries (SIBs). Nevertheless, large-scale commercial use is severely hampered by the slow reaction kinetics and rapid capacity fading. Heteroatom doping can create abundant active sites to improve the ion adsorption properties of carbon materials. Here, we report a novel nitrogen/boron co-doped carbon nanosheet (NB-CN) with abundant N–B bonds for efficient Na+ storage. B-doped MIL-68 as a carbon precursor can not only achieve uniform B doping but also serve as the nitrogen doping site to form N–B bonds. N, B co-doping could promote ion adsorption with improved hydrophilicity, while the 2D porous structure can accelerate the Na+ transfer kinetics. Benefitting from the synergistic effect of dual-doping and hierarchical porosity, NB-CN shows improved Na+ storage performance, NB-CN displays a high capacity of 307.1 mA h g−1 in SIBs at 0.1 A g−1, and still has a reversible capacity of 157 mA h g−1 for SIBs at 4 A g−1 after 8000 cycles. Moreover, the assembled NB-CNs//Na3V2(PO4)3/C full cell also exhibits the potential application prospect. This work provides an insight for designing dual-doped carbon materials for high-performance SIBs.