Designer interphases for the lithium-oxygen electrochemical cell

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-Oxygen (Li-O2) cells offer high energy density for applications like electric transportation.
• Practical Li-O2 cell development is hindered by anode, cathode, and electrolyte instability.
• Poor rechargeability and low specific energies limit current Li-O2 cell performance.

Purpose of the Study:

• To overcome critical challenges in Li-O2 battery technology.
• To improve the stability and efficiency of Li-O2 cells.
• To enable practical application of high-energy-density Li-O2 batteries.

Main Methods:

• In-situ formation of solid-electrolyte interphases (SEIs) using bromide ionomers tethered to a lithium (Li) anode.
• Studying the protective effects of SEIs on the Li anode during parasitic reactions and electrodeposition.
• Investigating the role of bromine species as redox mediators at the cathode.
• Analyzing SEI stability in high Gutmann donor number electrolytes.

Main Results:

• Ionomer SEIs effectively protect the Li anode from parasitic reactions and stabilize Li electrodeposition.
• Liberated bromine species act as redox mediators, significantly reducing cathode charge overpotential.
• The SEI creates a stable interphase with Li, crucial for high donor number electrolytes.
• Demonstrated mitigation of spontaneous reactions between Li metal anodes and reactive electrolytes.

Conclusions:

• Rationally designed SEIs are crucial for regulating ion and matter transport at the electrolyte/anode interface.
• SEIs offer a promising strategy to address major technical barriers in practical Li-O2 cells.
• This approach enhances Li-O2 battery rechargeability, efficiency, and overall performance.