Hybrid silicon-carbon nanostructured composites as superior anodes for lithium ion batteries

Abstract

We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area (about 25.5 in2) in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon (a-Si) works as the active material to store electrical energy, and the pre-coated carbon nanofibers (CNFs) serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of >2000 mA·h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of >98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.