Issue 13, 2024

A reversible self-assembled molecular layer for lithium metal batteries with high energy/power densities at ultra-low temperatures

Abstract

Electrolytes for low temperature, high energy lithium metal batteries are expected to possess both fast Li+ transfer in the bulk electrolytes (low bulk resistance) and a fast Li+ de-solvation process at the electrode/electrolyte interface (low interfacial resistance). However, the nature of the solvent determines that the two always stand at either ends of the balance, and conventional electrolyte designs have to make a compromise to favor one at the expense of the other. Here, we address this irreconcilable dilemma using an “electric-field assisted self-assembly layer”, i.e. sodium perfluorooctanoate (NaPFO). Driven by the bias-potential, PFO anions dissolved in the electrolyte could reversibly self-assemble into a dense and ordered molecular layer at the cathode/electrolyte interface, which could protect the electrolyte from anodic degradation due to the high voltage and enable the stable cycling of LiNi0.8Mn0.1Co0.1O2 (NMC811) in ether-based electrolyte with an ultra-low freeing point. More importantly, the self-assembly of the PFO layer could aid the Li+ de-solvation behavior at the cathode/electrolyte interface, thus significantly lowering the interfacial resistance. Thus, with this reversible self-assembly layer on the cathode surface, low bulk resistance and low interfacial resistance are simultaneously achieved. Consequently, the tetrahydrofuran (THF)-based electrolyte containing NaPFO is applied to practical Li‖NMC811 pouch cells and achieves an unprecedented energy density of 122 W h kg−1 (except taps and packing foil, same hereafter) at −85 °C, the highest reported power density of 318 W kg−1 at a high current density of 4.1 mA cm−2 at −60 °C, and can be recharged with stable performance (175 W h kg−1 at 20th cycles) at −40 °C. This electric-field assisted self-assembly layer enables fine tuning of the micro-environment at the cathode–electrolyte interface, and provides a new design concept for the electrolyte of ultra-low temperature high voltage lithium-metal batteries.

Graphical abstract: A reversible self-assembled molecular layer for lithium metal batteries with high energy/power densities at ultra-low temperatures

Supplementary files

Article information

Article type
Paper
Submitted
22 Mar 2024
Accepted
20 May 2024
First published
22 May 2024

Energy Environ. Sci., 2024,17, 4531-4543

A reversible self-assembled molecular layer for lithium metal batteries with high energy/power densities at ultra-low temperatures

W. Zhang, Y. Lu, Q. Cao, H. Liu, Q. Feng, P. Zhou, Y. Xia, W. Hou, S. Yan and K. Liu, Energy Environ. Sci., 2024, 17, 4531 DOI: 10.1039/D4EE01298D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements