Nano-MnS@ N doped lignite derived carbon composites as superior anode material for sodium-ion batteries

It is well known that sodium-ion batteries prepared by using MnS as anode material have higher theoretical capacity, electrochemical activity, and lower cost. Nevertheless, the rapid decay of capacity owing to the larger volume expansion and lower electrical conductivity during charge/discharge processes heavily hinder their practical utilization. To overcome these shortcomings, MnS@NC composites are synthesized with humic acid extraction residue of lignite as C source and urea as N source. In obtained MnS@NC composites, MnS nanoparticles dispersed uniformly on outer surface and inner wall of porous N doped C skeleton. When applied as anode material to sodium-ion batteries, its specific capacity remained to 461.2 mAh/g after 200 cycles at 0.1 A/g, superb rate capability, and excellent-good cycle stability. This outstanding electrochemical property is due to the existence of N doped C skeleton, which could not only buffer the volume expansion of MnS nanoparticles, but also offer it a superior electronic conductivity.