%0 Journal Article
%A Jagjit Nanda
%A Guang Yang
%A Tingzheng Hou
%A Dmitry N Voylov
%A Xin Li
%A Rose E Ruther
%A Michael Naguib
%A Kristin A Persson
%A Gabriel M Veith
%A Alexei P Sokolov
%B Joule
%D 2019
%G eng
%R 10.1016/j.joule.2019.05.026
%T Unraveling the Nanoscale Heterogeneity of Solid Electrolyte Interphase Using Tip-Enhanced Raman Spectroscopy
%8 01/2019
%! Joule
%X <p><span>We employ tip-enhanced Raman spectroscopy (TERS) to study model amorphous silicon (a-Si) thin film anodes galvanostatically cycled for different numbers. For the 1× cycled a-Si, TERS shows good correlation between solid electrolyte interphase (SEI) topography and chemical mapping, corresponding to distribution of lithium ethylene dicarbonate (LEDC) and poly (ethylene oxide) (PEO)-like oligomer species. Subsequent electrochemical cycling makes the SEI relatively thick and rough with the chemical composition heavily dominated by LEDC monomer-dimer for 5× cycled a-Si. For 20× cycled a-Si, the TERS signal is dominated by carboxylate (RCO</span><span>2</span><span>Li) compounds of various conformations and fluorinated species (Li</span><span>x</span><span>PO</span><span>y</span><span>F</span><span>z</span><span>). A nanomosaic-multilayer hybrid SEI model on top of the a-Si anode is proposed. The significance of this work is applicable not only to silicon, where SEI plays a dominant role in determining the cycle life performance and reversibility, but also for a number of other relevant battery chemistries such as Na-ion and multivalent redox systems.</span></p>