Onium salts-derived B and P dual-doped carbon microspheres as anode material for high-performance sodium-ion batteries

Boron (B) and phosphorus (P) dual-doped carbon microspheres (BPC) were successfully synthesized from onium salts by a facile one-step pyrolysis method. When employed as the anode material for sodium (Na)-ion batteries (NIBs), the resulting BPC delivers a reversible capacity of 221.9 mAh g−1 at 50 mA g−1. Impressively, the BPC can still deliver a capacity of 102 mAh g−1 after 1500 cycles at 1 A g−1 with the capacity retention up to 78%. The high performance of the BPC can be attributed to the significantly increased defects and dilated interlayer distance induced by synergistically B and P co-doping. [Display omitted] •B and P co-doped carbon (BPC) was synthesized from onium salts for the first time.•Co-doping with P (B) can synergistically promote the content of counterpart B (P).•The BPC delivers high capacity and excellent cycling stability for Na-ion storage.•Defects and dilated interlayer distance are the main factors for high performance.