A Highly Concentrated Electrolyte for High Capacity and Coulombic Efficiency in Li-NCM811 Cells

Top: Scanning electron microscopy (SEM) images showing numerous high-contrast features on the surface of Li metal after cycling in a cell with a 1 M LiPF6 electrolyte and lack of similar features for the HCE cell. Bottom: Galvanostatic cycling results showing higher discharge capacity and Coulombic efficiency for the HCE cell over the dilute 1 M LiPF6 cell.

Scientific Achievement

Replacing a dilute 1 M LiPF6-based electrolyte with a hydrofluoroether (HFE)-modified highly concentrated electrolyte (HCE) stabilizes the Li metal interface and results in higher discharge capacity, Coulombic efficiency, and thermal stability.

Significance and Impact

This study demonstrates that HCEs can be used with lithium metal anode and a high capacity cathode to improve the thermodynamic stability as well as the thermal stability of the electrolyte. Furthermore, replacing LiPF6 with a concentrated electrolyte can possibly mitigate some of the safety concerns regarding HF formation.

Research Details

  • The HCE mitigates the formation of dendrites and/or an inhomogeneous degradation layer as seen using SEM imaging.
  • The higher thermodynamic stability of the HCE against Li metal, as demonstrated through lower resistivity using electrochemical impedance spectroscopy, leads to higher discharge capacity and Coulombic efficiency.

Download this highlight

DOI: 10.1002/batt.202000192

Latest Updates

See All