Developing bio-carbon matrices for the encapsulation of silicon nanoparticles for high-performance lithium-ion...

Silicon (Si) is considered to be one of the most promising anode materials for next-generation lithium-ion batteries because of its abundant reserves, low discharge potential, and most importantly, its high theoretical specific capacity. However, the practical application of Si-based anodes is mainly hindered by the low intrinsic conductivity of Si and the large volume change upon lithiation/de-lithiation. In order to improve the electrochemical performance of Si-based anodes, we prepared a composite material consisting of Si nanoparticles (NPs) and coconut silk bio-carbon (CSC) skeleton. The porous carbon skeleton derived from coconut silk with natural through-holes and ample micropores on the wall, which was used as the carrier of Si NPs. The continuous through-holes and well-distributed oxygen-containing functional groups of the CSC provided sufficient space and abundant adsorption active sites for Si NPs, what's more, the good dispersion of Si NPs in the through-holes increased their contact with the surrounding carbon materials, which was conducive to electron transport. Meanwhile, the pore structure also provided buffer space for the volume expansion of Si. The rich oxygen-containing functional groups can form a certain chemical force with silicon particles, and further stabilize the nano silicon particles. Hence, the CSC/Si electrode revealed an excellent capacity retention of 82.8 % at 1 A g^-1 after 100 cycles. This study provides a simple universal high-throughput method to obtain anode materials with outstanding electrochemical properties and promotes the further development of Si/C composites.