Stable Low-Temperature Lithium Metal Batteries with Dendrite-Free Ability Enabled by Electrolytes with Cooperative Li+-Solvation

Abstract

In subzero environments, sluggish electrochemical kinetics and unstable electrode/electrolyte interphases hinder progress in lithium metal batteries (LMBs), emphasizing the need for advanced electrolytes to ensure stability in harsh environments. Herein, we proposed a balanced “cocktail optimized” electrolyte by manipulating solvated and anionic species. The dual salt/dual solvent electrolyte simultaneously achieves low bulk impedance and low interfacial impedance, while also demonstrating improved Li reversibility and oxidation stability. The tailored solvation structure encourages the breakdown of anions, leading to the formation of inorganic-rich interphases at both the cathode and Li-anode, which enables a uniform plating-stripping of Li while maintaining exceptional voltage resilience on the cathode. Moreover, NO3- ions preferentially adsorb onto the cathode surface within the inner Helmholtz plane, shielding the easily-oxidized non-solvating solvent molecules, a phenomenon referred to as the "shielding effect", thus inhibiting side oxidation reactions. Consequently, the anion-derived interface chemistry contributes to the dendrite-free Li deposition with a high CE of 99.45%, a stable cycling of Li||NCM523 battery with 85% capacity retention after 150 cycles, and a superior low-temperature discharge performance at -30 ℃ with a capacity retention of 68.2%. This work sheds light on an encouraging high-entropy electrolyte strategy for stable LMBs in a wide-temperature range.

Keywords: lithium metal batteries, low-temperature, cocktail electrolyte, dual salt/dual solvent electrolyte, High-entropy