Nitrogen/sulfur co-doped disordered porous biocarbon as high performance anode materials of lithium/sodium ion batteries

Nitrogen/sulfur co-doped disordered porous biocarbon was facilely synthesized and applied as anode materials for lithium/sodium ion batteries. Benefiting from high nitrogen (3.38 wt%) and sulfur (9.75 wt%) doping, NS1-1 as anode materials showed a high reversible capacity of 1010.4 mA h g−1 at 0.1 A g−1 in lithium ion batteries. In addition, it also exhibited excellent cycling stability, which can maintain at 412 mAh g-1 after 1000 cycles at 5 A g−1. As anode materials of sodium ion batteries, NS1-1 can still reach 745.2 mA h g−1 at 100 mAg-1 after 100 cycles. At a high current density (5 A g-1), the reversible capacity is 272.5 mA h g−1 after 1000 cycles, which exhibits excellent electrochemical performance and cycle stability. The preeminent electrochemical performance can be attributed to three effects: (1) the high level of sulfur and nitrogen; (2) the synergic effect of dual-doping heteroatoms; (3) the large quantity of edge defects and abundant micropores and mesopores, providing extra Li/Na storage regions. This disordered porous biocarbon co-doped with nitrogen/sulfur exhibits unique features, which is very suitable for anode materials of lithium/sodium ion batteries.