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.