Fe-N-C decorated fibrous network-wrapped biomass SiOx/C with gradient conductive structure for high performance Li-ion battery anodes

Fabrication of high performance silicon-based materials derived from natural biowastes plays a significant role in the green recycling of biomass resources. However, low utilization of organic component and poor lifespan hinders the its large scale applications. Herein, biomass derived SiOx/C-3 composite was encapsulated into Fe-N-C decorated carbon nanofibers network (Fe-N-C/SiOx/C-3) by a facile magnesiothermic reduction combined with electrostatic spinning strategy. The ingenious designed indirect contact biomass carbon/SiO2 interface effectively utilizes the organic components of rice husk and prevents the formation of SiC during reduction process. HAADF-STEM and XPS characterization confirmed the presence of Fe single atoms and the formation of Fe-N coordination bonds. Benefiting from the unique carbonaceous network and catalytic effect of Fe-N-C, the Fe-N-C/SiOx/C-3 exhibit excellent lithium storage properties (832.6 mAh g−1 after 250 cycles at 0.1 A g−1). Even at high current density (1 A g−1), the electrode can still remain a capacity of 602 mAh g−1 after 1000 cycles with capacity retention of 79.4%. The ex-situ SEM and XPS characterizations demonstrated that the gradient structure consisting of inner biomass-derived carbon and flexible carbonaceous networks enhanced the overall conductivity and structural integrity of the composite. Furthermore, the catalytic effect of Fe-N-C facilitates the rapidly formation of stable LiF-rich solid electrolyte interphase (SEI) films during charge/discharge process. The assembled LiFePO4‖Fe-N-C/SiOx/C-3 full cell shows excellent electrochemical performance (106.5 mAh g−1 after 100 cycles at 0.1A g−1), which provides insights into the fabrication of high performance biomass derived silicon based anodes.