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Facile and Cost Effective Directly Electrosprayed Graphene/Silicon Nanocomposites for High-Rate Lithium-Ion Battery Anodes

Monday, 14 May 2018
Ballroom 6ABC (Washington State Convention Center)
G. Shoorideh (Cornell Univesity), S. M. Park (Cornell University), A. Berry (Cornell Univesity), and Y. L. Joo (Cornell University)
Silicon is in the research spotlight for the next generation of Li-ion battery anodes due to its high specific capacity of 4200 mAh/g for lithium storage at room temperature. However, it has a few serious shortcomings that prevent its commercialization. In the present work, we explored a facile and environmentally friendly process based on electrospraying to directly deposit active material on the current collector and remedy silicon problems in one step. Instead of graphene-oxide or other derivatives, direct employment of a graphene suspension in the deposition process which does not require heat treatment to increase its conductivity enables usage of a polymeric binder in the system. As a result, the sprayed composite layer has a uniform morphology with an excellent dispersion of nanoparticles between graphene layers and an electrode density above 0.7 g/cc was prepared. Graphene sheets provide conductivity and keep the silicon nanoparticles in place during constant volume expansion/contraction. Nevertheless, existence of polymeric binder greatly increases the life of the electrodes with minimal capacity fading of about 15% after 300 cycles with a specific capacity of 2100 mAh/g. In addition, electrodes prepared with this technique have a noticeably high first cycle columbic efficiency up to 92%, which makes them desirable for full cell fabrication. These electrodes also have a great electrochemical performance at high rates (1200 mAh/g at 2C and 1000 at 5C), due to the highly conductive network of dispersed graphene sheets. In this presentation, the innovative and facile electrode preparation technique will be introduced and underlying phenomena responsible for the outstanding electrochemical performance of the fabricated electrodes will be discussed.