Abstract
The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery. C/SiOx active materials with different SiOx contents (45, 24, and 5 mass%) were prepared from rice husk by heat treatment and immersion in NaOH solution. The C and SiOx specific capacities were 375 and 475 mAh g−1, respectively. A stable anodic operation was achieved by pre-lithiating the C/SiOx anode. Full-cells consisting of this anode and a Li(Ni0.5Co0.2Mn0.3)O2 cathode displayed high initial Coulombic efficiency (~ 85%) and high discharge specific capacity, indicating the maximum performance of the cathode (~ 150 mAh g−1). At increased current density, the higher the SiOx content, the higher the specific capacity retention, suggesting that the time response of the reversible reaction of SiOx with Li ions is faster than that of the C component. The full-cell with the highest SiOx content exhibited the largest decrease in cell specific capacity during the cycle test. The structural decay caused by the volume expansion of SiOx 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, SiOx is preferably retained for Li-ion battery anode applications.
Highlights
The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery
These results demonstrate that SiOx is beneficial for increasing the specific capacity of C/SiOx active materials (AMs)
rice husk (RH)-derived C/SiOx AMs with 45, 24, and 5 mass% SiOx were prepared by heat treatment and immersion in a NaOH solution
Summary
The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery. High specific capacity for Li-ion uptake and release, good cycle stability, low toxicity, low cost, and natural abundance are required for anodic AMs. Graphite, which follows the insertion mechanism, is still mainly used in commercial LIBs because of its low and flat potential profile, low irreversible capacity, low cost, and accumulated experience. Si, which follows the alloying mechanism, is anticipated to supersede graphite because of its very high specific capacity (4200 mAh g−1 at full Li alloying)[14] It undergoes a large volume expansion during Li-ion uptake and release (~ 280%)[16], causing the cracking of Si particles and repeated formation of a solid-electrolyte interphase (SEI). C/SiOx composites have attracted much attention as anodic AMs for LIBs18–21
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