Investigation of electrolyte salts in non-flammable triethyl phosphate for sodium-ion batteries

DOI: 10.1002/batt.202400489

Authors: Wessel W. A. Van Ekeren (Uppsala University) , Lasse Dettmann (Uppsala University) , Yonas Tesfamhret (Altris AB) , Andrew J. Naylor (Uppsala University) , Reza Younesi (Uppsala University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Batteries & Supercaps

State: Published (Approved)
Published: October 2024
Diamond Proposal Number(s): 36213

Abstract: Five different electrolyte salts, namely NaBF4, NaClO4, NaDFOB, NaFSI and NaPF6, were evaluated in non-flammable triethyl phosphate (TEP) based electrolyte solutions in sodium-ion full-cells using high-mass loading Prussian white and hard carbon electrodes. Their impact on the viscosity, ionic conductivity and solvation structure was analyzed, revealing that NaFSI-based electrolytes exhibited a stronger interaction with TEP and less ion-pairing than the other salts, resulting in the highest ionic conductivity at a concentration of 0.8 m (mol/kg). Galvanostatic cycling experiments showed that none of the electrolyte salts dissolved in TEP forms an efficient passivation layer. However, adding 1 wt.% vinylene carbonate (VC) significantly improved cycling performance for the cells with NaBF4, NaDFOB or NaFSI, but not with NaClO4 or NaPF6. Additionally, NaFSI in TEP with 1 wt.% VC electrolyte solution showed minimal gas evolution during the formation cycling (< 8 mbar). In a 1 Ah multilayer pouch cell, 0.8 m NaFSI in TEP with 1 wt.% VC showed promising results with 88% capacity retention after 200 cycles. X-ray photoelectron spectroscopy analysis revealed that the addition of VC results in the formation of a thin SEI and minimized TEP decomposition on hard carbon, especially for 0.8 m NaFSI TEP with 1 wt.% VC.

Diamond Keywords: Batteries; Sodium-ion

Subject Areas: Materials, Chemistry, Energy


Instruments: I09-Surface and Interface Structural Analysis

Added On: 09/10/2024 14:03

Documents:
Batteries Supercaps - 2024 - Van Ekeren - Investigation of Electrolyte Salts in Non‐Flammable Triethyl Phosphate for.pdf

Discipline Tags:

Surfaces Energy Storage Energy Physics Physical Chemistry Energy Materials Chemistry Materials Science

Technical Tags:

Spectroscopy X-ray Photoelectron Spectroscopy (XPS)