Activation Energies of Crystallization Events in Electrochemically Lithiated Silicon

Li/Si coin cells were assembled using crystalline Si as a negative electrode material. The Si was electrochemically lithiated and delithiated to various states of charge. Differential scanning calorimetry studies at heating rates varying from 1 degrees C/min to 20 degrees C/min were performed and analyzed to yield activation energies for crystallization reactions occurring in lithiated Si with increasing temperatures. Activation energies requiring mainly the diffusion of Li atoms were near or below 150 kJ/mol while activation energies requiring the reworking of Si bonds were near or above 300 kJ/mol. Avoiding the formation of Li(15)Si(4) did not significantly impact the DSC signals of delithiated alpha-Li(x)Si samples. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.009111jes] All rights reserved.