Multi-Valent Cation Strategies for Controlling Interphase Chemistry at the Lithium Metal Anode.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• The solid electrolyte interphase (SEI) is critical for lithium metal battery (LMB) performance, governing lithium deposition and dissolution.
• Current methods to improve SEI often involve increasing conducting salt concentrations, raising costs and environmental concerns.

Purpose of the Study:

• To introduce a cost-effective and environmentally friendly multi-valent cation (MVC) approach for superior LMB performance.
• To demonstrate enhanced SEI formation and stability in LMBs using minimal magnesium carbonate.

Main Methods:

• Addition of a small amount (0.05 m) of magnesium carbonate (MgCO3) to a lithium hexafluorophosphate (LiPF6) based electrolyte.
• Utilizing Mg2+ cations to scavenge hydrogen fluoride (HF) and promote the formation of an anion-derived SEI.
• Evaluating the performance of LiNi0.8Mn0.1Co0.1O2 (NMC811)||Li cells under galvanostatic cycling.

Main Results:

• The MVC approach effectively scavenges HF, leading to the release of Mg2+ cations.
• Mg2+ cations promote the formation of a stable, anion-derived SEI layer.
• Demonstrated enhanced reversibility of lithium deposition/dissolution and stable cycling of NMC811||Li cells.

Conclusions:

• The MVC approach offers a highly effective strategy for designing anion-derived SEI in LMBs.
• This method improves lithium metal interface stability and battery performance without increasing salt concentration.
• Provides new insights into controlling SEI formation for advanced energy storage applications.