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

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 LiPF ₆-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) LiNi _0.8Co _0.1Mn _0.1O ₂-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.

Abstract

Lithium metal batteries suffer from poor (electro)chemical stability of the electrodes during prolonged cycling. Here, the authors report a dual function liquid electrolyte additive to form protective interphases on both electrodes to produce lab-scale high energy lithium metal batteries.