Biomass-derived SiO_x/C nanocomposite anode synthesis by induction heating for lithium ion battery

Graphite is the main anode active material used in commercial lithium ion batteries and it is currently included in the European Union’s Critical Raw Materials list. Due to increased demand in the battery market, a global graphite shortage is expected within the next five years. Therefore, an alternative anode active material is needed to substitute graphite. Motivated by this need, this paper proposes a green synthesis method for producing SiO_x/C nanocomposite anode active material from an organic waste, namely rice husk, via a single-step induction heating process. In this study, for the first time in the open literature, rice husk is pyrolyzed under a controlled atmosphere with fast heating (> 50 °C/min) to be used as an alternative to graphite for lithium ion batteries. Fast heating is employed to preserve the maximum amount of carbon in the structure with minimal agglomeration. Four samples (800-Ar, 750-Ar, 700-Ar, 700-Ar-H) are fabricated to study the effect of pyrolysis conditions (temperature and atmosphere) on the formation of rice husk-derived amorphous SiO_x/C nanocomposite anodes, also referred to as biochar. Their electrochemical performances are then tested. Biochar produced at 700 °C under the argon atmosphere (700-Ar) delivers the highest specific capacities of 1366, 800, and 275 mAh/g in the 1st, 5th, and 200th cycles. This is attributed to the reduction of silica to SiO_x and high amount of carbon, which creates conductive pathways in the structure while buffering volumetric expansion during cycling. Graphical abstract: (Figure presented.)