Nitrogen-doped carbon/SiO_x composites from rice husks as a high-performance anode for lithium-ion batteries

摘要

Rice husks as agricultural waste contain abundant Si, C and N elements. We used rice husks as raw materials, ZnCl_2 as morphology control agent via a simple magnesiothermic reduction method to prepare nitrogen-doped carbon/SiO_x (N-C/SiO_x) composites as anode materials of lithium ion batteries. The composites exhibit high reversible capacity (at a current density of 100 mA g~(-1), after 100 cycles the discharge capacity as high as 1110 mAh g~(-1)), excellent cycling stability and outstanding rate performance (the discharge capacity reach 896, 665, 440, 310 and 225 mAh g~(-1) at the current density of 100, 200, 500, 1000 and 2000 mA g~(-1), respectively). The nice electrochemical performance of N-C/SiO_x anode materials attribute to the composites with ultrafine nanoparticles, which can release the stress generated during volume expansion timely. In addition, carbon in the composites is highly available to reduce the side reaction. Besides, N doping is an efficient way to improve the conductivity of composites. The rice husks-drived N-C/SiO_x composites synthesized by an environmentally friendly and economically method with satisfied electrochemical performance, which provide a promise for commercial of Si-based anode materials.