Nanostructured Silicon- Carbon Hybrid Anode for Lithium Ion Battery

Abstract

Si has garnered considerable interest due to its substantial lithium storage capacity of 3590 mAh g -1 . However, its extensive volume dilatation over 300% upon lithiation limits its practical implementation. In this work, we present a hybrid Si-C composite synthesized from carbon rich preceramic polymer and milled Si particles. Pyrolyzing the mix at different temperatures followed by HF etching yielded the desired Si-C composites, whose phase, microstructure, and electrochemical performance were studied. The composite fabricated with 1:2 ratio of silicon nanoparticles and preceramic polymer pyrolyzed at 1200 ºC followed by etching exhibited the maximum stable capacity of 1048 mAh g -1 after 200 th cycle at a current density of 0.1 A g -1 . The sample also demonstrated excellent rate capabilities with a capacity of 840 mAh g -1 at a high current density of 2 A g -1 . The porous preceramic polymer derived carbon phase that encapsulated the Si nanoparticle with its graphitic structure and etching-induced porosity was able to absorb the mechanical strain resulting from lithiation-induced dilatation of silicon as well as impart enhanced electronic conductivity facilitating efficient cycling at high current rates.