Triple-function eutectic solvent additive for high performance lithium metal batteries

Wenqiang Fang; Zuxin Wen; Fenglin Wang; Long Chen; Ying Zhang; Ning Zhang; Xiaohe Liu; Gen Chen

doi:10.1016/j.scib.2024.02.009

Triple-function eutectic solvent additive for high performance lithium metal batteries

Sci Bull (Beijing). 2024 Feb 9:S2095-9273(24)00078-1. doi: 10.1016/j.scib.2024.02.009. Online ahead of print.

Authors

Wenqiang Fang¹, Zuxin Wen¹, Fenglin Wang¹, Long Chen¹, Ying Zhang², Ning Zhang¹, Xiaohe Liu², Gen Chen³

Affiliations

¹ School of Materials Science and Engineering, Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan Province, Central South University, Changsha 410083, China.
² Zhongyuan Critical Metals Laboratory, School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China.
³ School of Materials Science and Engineering, Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan Province, Central South University, Changsha 410083, China. Electronic address: geenchen@csu.edu.cn.

PMID: 38423878
DOI: 10.1016/j.scib.2024.02.009

Abstract

Rational carbonate electrolyte chemistry is critical for the development of high-voltage lithium metal batteries (LMBs). However, the implementation of traditional carbonate electrolyte is greatly hindered by the generation of an unstable electrode interphase and corrosive by-product (HF). Herein, we propose a triple-function eutectic solvent additive of N-methylacetamide (NmAc) with LiNO₃ to enhance the stability and compatibility of carbonate electrolyte. Firstly, the addition of NmAc significantly improves the solubility of LiNO₃ in carbonate electrolyte by forming an eutectic pair, which regulates the Li⁺ solvation structure and leads to dense and homogenous Li plating. Secondly, the hydrolysis of acidic PF₅ is effectively alleviated due to the strong complexation of NmAc with PF₅, thus reducing the generation of corrosive HF. In addition, the optimized cathode electrolyte interphase layer decreases the structural degradation and transition metal dissolution. Consequently, Li||LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cells with the designed electrolyte deliver superior long-term cycle reversibility and excellent rate capability. This study unveils the rationale for incorporating eutectic solvent additives within carbonate electrolytes, which significantly contribute to the advancement of their practical application for high-voltage LMBs.

Keywords: Eutectic solvent additive; Interfacial chemistry; Lithium metal battery; PF(5) capturer; Solvation structure.