Ionic liquid-induced interfacially bonding of bio-based RH-Si/SiOx@C anodes for enhanced ultra-long cycling of Li-ion batteries

Silicon (Si) as anode material has a very high theoretical specific capacity for lithium-ion batteries (LIBs), but there are serious problems such as volume expansion and poor conductivity. Even though abundant carbon-silicon composite has been designed to alleviate these problems, the unstable carbon-silicon interface makes it hard to present high-performance. Herein, we created a core-shell structure (RH-Si/SiO x @C) that had a robust carbon-silicon interface with Si–C, Si–O–C, and Si–N bonding between rice husk-derived silicon nanoparticles (Si NPs) and pitch-derived soft carbon induced by 1-butyl-3-methyl-imidazole acetate ([BMIm]Ac). The pitch-derived soft carbon was evenly coated on the Si NPs and supplied outstanding electrical conductivity, while the oxygen of pitch and [BMIm]Ac caused SiO x growth on the Si NPs surface to buffer expansion. RH-Si/SiO x @C electrode demonstrated extraordinary long-term cycling performance for LIBs. After going through 1000 cycles at 2 A g −1 , it still possessed 89.78% retention and kept 622 mAh g −1 . When the test current was applied to 3 A g −1 , it maintained a 357 mAh g −1 specific capacity with 60.16% retention. RH-Si/SiO x @C has a lot of promise for high-energy-density LIBs because of its outstanding electrochemical performance and easy fabrication procedures. • Ionic liquids built robust C/Si interfaces by Si–O–C, Si–C, and Si–N bonds. • A homogenous coating of soft carbon increased electric conductivity. • The RH-Si/SiOx@C shows excellent long-term cycle performance.