645
Selectively-Etched Silicon/Graphite Nanocomposites As Anode Materials for Li-Ion Batteries: Towards the Reduced-Cost Battery

Tuesday, 21 June 2016
Riverside Center (Hyatt Regency)
M. Ashuri, Q. He, S. Emani (Illinois Institute of Technology, Wanger Institute for Sustainable Energy Research), and L. Shaw (Wanger Institute for Sustainable Energy Research, Illinois Institute of Technology)
Silicon with more than 4000 mA h g-1 theoretical specific capacity is one of the most promising candidates for replacing conventional graphite anodes in Li-ion batteries. However, due to the huge volume change in cycling, the specific capacity fades fast. Several strategies have been proposed, but the best results were obtained by special designs (such as core-shell, yolk-shell, etc.) along with reducing grain size to nm scale. These strategies have improved the specific capacity dramatically, but most of them do not have the potential for mass production. Here, we report a facile synthesis method which is based on the idea of making composites of silicon and graphite, which are abundant and cheap. Silicon and graphite were mixed together with the weight ratio of 90:10 and high-energy ball milled before carbon coating via carbonization of pyrrole. The carbon-coated powder was then etched with 0.5 M NaOH solution to create carbon-encapsulated Si/graphite composites with engineered void (i.e., Si/graphite@void@carbon). For comparisons Si/graphite@void@carbon was also synthesized via carbon coating with polydopamine (PODA) as the precursor. Both Si/graphite@void@carbon powders were utilized to fabricate CR2032 coin cells with Li chip as the counter electrode. Electrochemical results of Si/graphite@void@carbon were compared to those of both micron- and nano-sized silicon particles and discussed.