• Schulze, Maxwell C.
• Han, Sang-Don
• Frisco, Sarah
• Rynearson, Leah
• Teeter, Glenn
• Lucht, Brett
• Neale, Nathan R.

Abstract

<jats:p>Unstable electrode/electrolyte interface is the major cause of degradation for silicon (Si)-based anodes for lithium (Li)-ion batteries. Development of functional electrolyte additives can provide a viable path toward stabilizing the dynamic Si/electrolyte interface, which will benefit the development of high energy density Li-ion batteries. Here, we evaluate polymerizable electrolyte additives with varying functional groups (fluorocarbon, thiophosphate, and fluorophosphazene). The additives are examined using LiNi<jats:sub>0.6</jats:sub>Mn<jats:sub>0.2</jats:sub>Co<jats:sub>0.2</jats:sub>O<jats:sub>2</jats:sub>/Si full cells where the cycle performance and impedance are measured. Electrochemical tests show that the fluorine-containing additives provide better passivation at the Si electrode, leading to enhanced full cell performance. Among the three additives examined, best electrochemical performance is observed from the fluorocarbon-containing compound, followed by fluorophosphazene- and thiophosphate-containing compounds. Characterization of the solid electrolyte interphase (SEI) on cycled electrodes using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) reveal that higher concentration of fluorine and lithium oxide, and lower concentration of carbonate and organic species correlate with enhanced electrochemical performance.</jats:p>

Topics

• density
• impedance spectroscopy
• compound
• energy density
• x-ray photoelectron spectroscopy
• Silicon
• Lithium
• Fourier transform infrared spectroscopy
• atomic emission spectroscopy
• Auger electron spectroscopy