Lithium Sulfide Anolyte Layer for Dendrite Prevention
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Solution Overview
Problem
Lithium-ion rechargeable batteries face safety concerns and limitations due to the use of liquid electrolytes, which can react with lithium metal anodes and copper current collectors, and are prone to lithium dendrite formation, leading to electrical shorts.
Innovation Solution
A negative electrode assembly with a lithium sulfide anolyte layer is introduced, where a sulfur-containing layer reacts with a metal current collector to form a metal sulfide, which is then converted into a lithium sulfide anolyte, providing a protective layer and ion-conductive pathway between the lithium metal anode and the electrolyte, thereby preventing dendrite formation and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If liquid electrolytes are used in lithium-ion batteries, then high ionic mobility is achieved, but safety concerns arise due to reactions with lithium metal anodes and copper current collectors
Solution Approach 1:
A solid electrolyte interlayer is introduced as an intermediary between the liquid electrolyte and the lithium metal anode/copper current collector. This interlayer acts as a protective barrier that prevents direct contact and harmful reactions between the liquid electrolyte and electrode components, while still allowing lithium ion transport. The interlayer mediates the interaction between the liquid electrolyte and electrode, resolving the safety issue without compromising ionic mobility.
2Speed
If liquid electrolytes are used, then high ionic conductivity is maintained, but lithium dendrite formation occurs leading to electrical shorts
Solution Approach 1:
The solid electrolyte interlayer serves as a mediator between the liquid electrolyte and lithium metal anode, preventing lithium dendrite penetration. The interlayer's solid structure physically blocks dendrite growth while its ion-conductive properties maintain high ionic conductivity for normal lithium ion transport. This resolves the harmful effect of dendrite formation without sacrificing ionic conductivity.
3Reliability
If sulfide-based solid electrolytes are used to improve safety, then chemical compatibility with copper current collectors deteriorates
Solution Approach 1:
The solid electrolyte interlayer acts as a protective intermediary between the sulfide-based solid electrolyte and the copper current collector. This interlayer prevents direct chemical interaction between the sulfide electrolyte and copper, avoiding the formation of copper sulfides and associated negative effects. The interlayer maintains chemical compatibility while allowing the sulfide electrolyte to provide its safety benefits.
4Reliability
If a protective layer is formed on the current collector, then safety is improved, but device complexity increases
Solution Approach 1:
The solid electrolyte interlayer is merged with the existing electrolyte system, forming an integrated layered structure where the interlayer and bulk electrolyte work together as a unified ion-conductive medium. This merging approach incorporates the protective function without creating a completely separate complex system, as the interlayer is seamlessly integrated into the electrolyte pathway between electrodes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lithium sulfide anolyte layer improves safety by preventing lithium dendrite growth and electrical shorts, while maintaining high ionic conductivity, allowing for the use of lithium metal anodes without intercalation or alloying mediums and reducing irreversible lithium loss.
Implementation Method 1
Sulfur from the sulfur based electrolyte or from the sulfur-containing layer which contacts the metal layer reacts with the metal layer of the current collector and forms a metal sulfide layer
Implementation Method 2
the anolyte provides a protective layer over a lithium metal anode and an ion conducting pathway between the lithium metal anode and an electrolyte in contact with the anolyte
Implementation Method 3
When lithium is later added to, or conducted through, the metal sulfide layer, a lithium sulfide anolyte layer is formed while the metal layer is recovered or reduced
Data Source
AI summary
Provided are negative electrode assemblies containing lithium sulfide anolyte layers, electrochemical cells including these assemblies, and methods of forming thereof. An anolyte layer may be disposed over a metal layer of a current collector and may be used to separate the current collector from the rest of the electrolyte. The metal layer may include copper or any other suitable metal that forms in situ a metal sulfide during fabrication of the electrode assembly. Specifically, a sulfur containing layer, such as a solid electrolyte, is formed on the metal layer. Sulfur from this layer reacts with the metal of the current collector and forms a metal sulfide layer. When lithium is later added to the metal sulfide layer, a lithium sulfide anolyte layer is formed while the metal layer is recovered. Most, if not all operations may, be performed in situ during fabrication of electrochemical cells.