A dual-function liquid electrolyte additive for high-energy non-aqueous lithium metal batteries

Yuji Zhang,Danni Lei,Jinghao Chen,Chengxin Wang,Huiyi Li,Yuan Wu

doi:10.1038/s41467-022-28959-5

Abstract

Engineering the formulation of non-aqueous liquid electrolytes is a viable strategy to produce high-energy lithium metal batteries. However, when the lithium metal anode is combined with a Ni-rich layered cathode, the (electro)chemical stability of both electrodes could be compromised. To circumvent this issue, we report a combination of aluminum ethoxide (0.4 wt.%) and fluoroethylene carbonate (5 vol.%) as additives in a conventional LiPF6-containing carbonate-based electrolyte solution. This electrolyte formulation enables the formation of mechanically robust and ionically conductive interphases on both electrodes’ surfaces. In particular, the alumina formed at the interphases prevents the formation of dendritic structures on the lithium metal anode and mitigate the stress-induced cracking and phase transformation in the Ni-rich layered cathode. By coupling a thin (i.e., about 40 μm) lithium metal anode with a high-loading (i.e., 21.5 mg cm−2) LiNi0.8Co0.1Mn0.1O2-based cathode in coin cell configuration and lean electrolyte conditions, the engineered electrolyte allows a specific discharge capacity retention of 80.3% after 130 cycles at 60 mA g−1 and 30 °C which results in calculated specific cell energy of about 350 Wh kg−1.

Highlights

Engineering the formulation of non-aqueous liquid electrolytes is a viable strategy to produce high-energy lithium metal batteries
The design of improved nonaqueous liquid electrolyte solutions to construct a consistent and robust solid electrolyte interphase (SEI) at the anode and a cathode-electrolyte interphase (CEI) at the cathode is critical to the practical utilization of high specific energy LMBs14,15
The color of the Al(EtO)3-containing electrolyte (AFE, 0.4 wt.% Al(EtO)[3] and 5 vol.% fluoroethylene carbonate (FEC) in 1 M LiPF6/ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1 by volume)) in a polyolefin bottle that was placed in an Ar-filled glove box for five days at 30 °C and 60 °C turns from transparent to brown and produces an acidic gas (Supplementary Figs. 1 and 2), suggesting that side reactions were occurring

Summary

Introduction

Engineering the formulation of non-aqueous liquid electrolytes is a viable strategy to produce high-energy lithium metal batteries. With the synergistic effect of Al(EtO)[3] and fluoroethylene carbonate (FEC), Al2O3-containing interphases that provide robust and high ionic conductivity protection are formed, which is beneficial to both Li metal anodes and Ni-rich NCM cathodes.

Results

Conclusion