Nanostructured Si/C Composite with Porous Architecture as an Anode Material for Li-Ion Battery

Abstract

Silicon is one of the most promising anode materials for replacing conventional graphite-based anode for Li-ion batteries due to its highgravimetric capacity and a volumetric capacity. However, Si undergoes volume change (~400%) during the Li alloying process, which leads tosevere mechanical strain on the particles and results in decay of specific capacity. To mitigate such problems, we demonstrate the synthesis ofporous structured Si/C composite by using the co-assembly of Si nanoparticles, SiO2 , and phenolic resin, followed by a carbonizing process andthe subsequent removal of the SiO2 template to create pores. In the nanostructured Si/C composite, the porous carbon structure is expected toabsorb the mechanical strain originating due to the lithiation/delithiation process and also improve the electronic conductivity. Various analyticalcharacterization tools, such as XRD, Raman spectroscopy, BET, XPS, FE-SEM, and TEM, are used to evaluate the phase, structure, andmicrostructure of the Si/C composite. Later, the electrochemical performance of the Si/C composite in the half cell is studied. TEM reveals theentrapping of Si nanoparticles in the mesoporous carbon matrix, which helps to facilitate the easy diffusion of Li-ion. BET confirms the presenceof mesopores in the structure. The porous Si/C composite delivered a stable discharge capacity of 730 mAh g−1over 100 cycles at 100 mA g−1witha coulombic efficiency of more than 99 %.