Stable Lithium Electrodeposition in Liquid and Nanoporous Solid Electrolytes

TL;DR

This study demonstrates that lithium electrodeposition in liquid and nanoporous electrolytes can be stabilized over long cycles, challenging the belief that metal deposition instability is unavoidable due to inherent metal properties.

Contribution

The paper shows that simple liquid electrolytes with halogenated salts enable stable lithium electrodeposition, supported by surface energy and impedance analysis, confirming theoretical predictions about surface mobility.

Findings

Stable cycling with no deposition instabilities over hundreds of cycles

Enhanced surface mobility of lithium in halogenated salt electrolytes

Surface energy analysis explains stability mechanisms

Abstract

Rechargeable lithium, sodium, and aluminum metal-based batteries are among the most versatile platform for high-energy, cost effective electrochemical energy storage. Non-uniform metal deposition and dendrite formation on the negative electrode during repeated cycles of charge and discharge are major hurdles to commercialization of energy storage devices based on each of these chemistries. A long held view is that unstable electrodeposition is a consequence of inherent characteristics of these metals and their inability to form uniform electrodeposits on surfaces with inevitable defects. We report on electrodeposition of lithium in simple liquid electrolytes and in nanoporous solids infused with liquid electrolytes. We find that simple liquid electrolytes reinforced with halogenated salt blends exhibit stable long-term cycling at room temperature, often with no signs of deposition instabilities over hundreds of cycles of charge and discharge and thousands of operating hours. We rationalize these observations with the help of surface energy data for the electrolyte/lithium interface and impedance analysis of the interface during different stages of cell operation. Our findings provide support for an important recent theoretical prediction that the surface mobility of lithium is significantly enhanced in the presence of lithium halide salts.