Low-Temperature Performance Limitations of Lithium-Ion Batteries

Abstract

This work considers root causes for diminished performance of Li-ion cells at cold conditions, and provides suggestions toward improving low-temperature performance through modified electrolyte compositions. This evaluation considers concentration polarization, lithium desolvation, and potential electrolyte phase transformations from solid surface-driven Gibbs Adsorption processes. A new lumped parameter, denoted as Li-STEP, is used to describe the contribution of lithium desolvation to interfacial phenomena. Additionally, supporting insights are provided from test data for 18650 Li-ion cells and Li-ion button cells. The analyses suggest that at lower temperatures, poor transport properties of an EC-based electrolyte promote high concentration polarization, yielding localized enriched and depleted electrolyte regions that cause higher cell impedance and that can shift local thermodynamics to favor phase formation of EC-rich solid phases. Analysis of Li-STEP for an EC-based electrolyte suggests the lithium desolvation process accounts for roughly half of the activation energy required for lithium transport through interfacial regions.