Methodologies for Design, Characterization and Testing of Electrolytes that Enable Extreme Fast Charging of Lithium-Ion Cells

Ningshengjie Gao, Sangwook Kim, Parameswara Chinnam, Eric Dufek, Andrew Colclasure, Andrew Jansen, Seoung-Bum Son, Ira Bloom, Alison Dunlop, Stephen Trask, Kevin Gering

Research output: Contribution to journalArticlepeer-review

24 Scopus Citations

Abstract

Selection, testing and validation of electrolyte candidates for Li-ion cells are discussed, based on a 10-minute target for extreme fast charge (XFC). A combination of modeling and laboratory measurements create a timely and synergistic approach to identifying candidate electrolyte formulations. Multi-solvent systems provide a balanced set of properties, wherein lower molecular-weight solvents offer reduced viscosity, increased species diffusivity, and mitigation of concentration polarization at high charge rates. Carefully selected formulations can exhibit peak conductivity and usable conductivity range of two to three times that of the baseline EC-EMC (3:7, wt.) + LiPF6. Candidates are also chosen based on stability and longevity within the cell environment. Lab testing coincides with property predictions from the Advanced Electrolyte Model (AEM) and a macro-scale cell model. Cell testing utilized coin and pouch cells having NMC532 or NMC811 cathodes with graphite electrodes. Results indicate combinations of low-molecular weight solvents are key for fast-charge electrolytes as they extend the useful conductivity range to both low and higher salt concentrations, and possess higher self-diffusivities compared to conventional solvents. This reduces impacts from concentration polarization. The choice of electrolyte also influences the tendency for lithium metal deposition at the anode, as showcased by experimental and modeling results herein.

Original languageAmerican English
Pages (from-to)296-312
Number of pages17
JournalEnergy Storage Materials
Volume44
DOIs
StatePublished - Jan 2022

Bibliographical note

Publisher Copyright:
© 2021

NREL Publication Number

  • NREL/JA-5700-79866

Keywords

  • advanced electrolyte model (AEM)
  • cell transport model
  • extreme fast charge
  • lithium metal plating
  • lithium-ion batteries

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