Role of SiO in rice-husk-derived anodes for Li-ion batteries.

The present study investigated the role of SiO in a rice-husk-derived C/SiO anode on the rate and cycling performance of a Li-ion battery. C/SiO active materials with different SiO contents (45, 24, and 5 mass%) were prepared from rice husk by heat treatment and immersion in NaOH solution. The C and SiO specific capacities were 375 and 475 mAh g, respectively. A stable anodic operation was achieved by pre-lithiating the C/SiO anode. Full-cells consisting of this anode and a Li(NiCoMn)O cathode displayed high initial Coulombic efficiency (~ 85%) and high discharge specific capacity, indicating the maximum performance of the cathode (~ 150 mAh g). At increased current density, the higher the SiO content, the higher the specific capacity retention, suggesting that the time response of the reversible reaction of SiO with Li ions is faster than that of the C component. The full-cell with the highest SiO content exhibited the largest decrease in cell specific capacity during the cycle test. The structural decay caused by the volume expansion of SiO during Li-ion uptake and release degraded the cycling performance. Based on its high production yield and electrochemical benefits, degree of cycling performance degradation, and disadvantages of its removal, SiO is preferably retained for Li-ion battery anode applications.