Evaluating the Effect of Electrolyte Additive Functionalities on NMC622/Si Cell Performance

Yeyoung Ha, Trevor Martin, Sarah Frisco, Leah Rynearson, Maxwell Schulze, Sang-Don Han, Stephen Trask, Brett Lucht, Glenn Teeter, Nathan Neale

Research output: Contribution to journalArticlepeer-review

12 Scopus Citations

Abstract

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 LiNi0.6Mn0.2Co0.2O2/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.

Original languageAmerican English
Article number070515
Number of pages8
JournalJournal of the Electrochemical Society
Volume169
Issue number7
DOIs
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

NREL Publication Number

  • NREL/JA-5K00-82464

Keywords

  • electrolyte additives
  • Li-ion batteries
  • Si anodes

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