Microscopy Investigation of Streblus asper Lour. Leaves-derived SiO2/C with Polypyrrole Nanocomposites as Sustainable Anode Materials for Lithium-ion Batteries

Lith ium-ion batteries (LIBs) are chemically reactive rechargeable energy storages. Silica (SiO2) is one of the most popular alternative materials to replace graphite as an anode material in LIBs due to its higher specific capacity, non-toxicity, and natural resources. Streblus asper Lour. (Khoi) is widely grown in Southeast Asia and contains high SiO2 and SiO2/C levels in its leaves. In order to overcome the volume change issue of Si-based materials and enhance cycle stability, carbon (C) and polypyrrole (PPy) were utilized to reinforce the SiO2 structure during the lithiation/delithiation process. X-ray diffraction (XRD) was utilized to investigate the SiO2, C, and PPy amorphous phases of the synthesized products. Fourier transform infrared spectroscopy (FT-IR), which confirmed the formation of PPy in composites. The scanning electron microscopy (SEM) images revealed different morphologies of SiO2 aggregates, SiO2/C with plate layers, the network structure of PPy and in the composites with PPy. Transmission electron microscopy (TEM) revealed the aggregation of nano-sized SiO2, SAED phase confirmation, and demonstrated the coating of PPy on SiO2/C (KSCPy composites), indicating the presence of C and PPy as supporters. In addition, the performance of synthesized composites as anodes was investigated by assembling them into half-coin cells and performing electrochemical tests. Khoi-SiO2/C/PPy (KSCPy) obtained a specific capacity of 497.9 mA g−1 for 400 cycles at 0.1 A g−1 and the lowest charge transfer resistance. Furthermore, these materials have the potential to be used as sustainable anode materials in LIBs due to their use of natural materials, a non-toxic synthesis method, and C and PPy as both support materials and conductive polymers, which can enhance electrical performance as anode materials