Stabilizing the cycling stability of rechargeable lithium metal batteries with tris(hexafluoroisopropyl)phosphate additive

The application of rechargeable lithium metal batteries (LMBs) has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the elec-trolyte at the interface. Here, we have developed a non-flammable triethyl phosphate (TEP)-based elec-trolyte with tris(hexafluoroisopropyl)phosphate (THFP) as an additive. The polar nature of the C-F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable, LiF-rich solid electrolyte interphase (SEI) layer through the reduction of THFP and increases the binding ability of the PF6 & DBLBOND; anions, which significantly suppresses lithium dendrite growth and reduces the elec-trolyte decomposition. Moreover, THFP participates in the formation of a thin, C-F rich electrolyte inter-phase (CEI) layer to provide the stable cycling of the cathode at a high voltage. The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life, which demon-strates the importance of the additive to the application of the LMBs. (C)& nbsp;2022 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

A non-flammable triethyl phosphate (TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate (THFP) as an additive has been developed. THFP helps to form a stable LiF-rich solid electrolyte interphase (SEI) layer, suppress lithium dendrite growth, and reduce electrolyte decomposition. THFP also participates in the formation of a stable electrolyte interphase (CEI) layer for stable cycling of the cathode.