Lithium Metal Electrode Protective Layer for Stable SEI Formation

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Solution Overview

Problem

Lithium metal batteries face issues with unreliable performance and premature electrochemical cell failure due to side reactions between lithium metal and the electrolyte, leading to solid-electrolyte interface (SEI) formation and electrolyte decomposition.

Innovation Solution

A fluorine-rich artificial solid-electrolyte interphase (SEI) layer is developed for lithium metal electrodes, comprising a carbonaceous matrix with lithium fluoride and a nitrate salt distributed within, formed from a fluoropolymer. This layer is designed to reduce side reactions and enhance the stability of lithium metal batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium metal is used as the negative electrode material to achieve high energy density, then the battery capacity and energy storage are improved, but side reactions occur between lithium metal and electrolyte leading to SEI formation and electrolyte decomposition

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrochemical cell stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A protective layer comprising a carbonaceous matrix with distributed lithium fluoride and nitrate salt is introduced as an intermediary between the lithium metal electrode and the electrolyte. This protective layer acts as a mediator that prevents direct contact and harmful side reactions between lithium metal and electrolyte, while still allowing lithium ion transport, thus resolving the contradiction between achieving high capacity and maintaining stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is constructed as a composite material system combining carbonaceous matrix, lithium fluoride, and nitrate salt. This composite structure provides both mechanical integrity and chemical functionality, creating a stable interface that prevents electrolyte decomposition while maintaining electrochemical performance, thereby addressing the reliability issue of lithium metal batteries.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium metal is used as the negative electrode material to achieve high energy density, then the battery capacity is improved, but premature electrochemical cell failure occurs due to continuous electrolyte decomposition

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery cycle life

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The protective layer is formed in advance on the lithium metal electrode surface before the battery operates. This preliminary protective coating prevents continuous electrolyte decomposition during cycling by blocking direct contact between electrolyte and lithium metal, thereby extending battery cycle life while preserving high capacity characteristics.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective layer converts the harmful effect of lithium metal reactivity into a beneficial protective function. By utilizing the reactive lithium metal to form a stable protective interface layer containing lithium fluoride and nitrate salt, the system transforms potential degradation mechanisms into a protective mechanism that enhances long-term stability and cycle life.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 protective SEI layer effectively suppresses lithium metal side reactions, improving the cycle life and capacity retention of lithium metal batteries, thereby addressing the issues of unreliable performance and premature failure.

Implementation Method 1

the fluoropolymer and the lithium-containing electroactive material layer to form a carbonaceous matrix and a lithium fluoride byproduct

Methodology Applied

Scientific EffectDefluorination reaction: Chemical Bonding

Implementation Method 2

The nitrate salt and the lithium fluoride byproduct may be dispersed within the carbonaceous matrix defining the protective layer

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS12334539B2Protective layers for lithium metal electrodes and methods of forming the same

Publication Date: 2025.06.17 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

An electrode assembly that includes an electroactive material layer and a protective layer disposed on or adjacent to the electroactive material layer is provided. The protective layer includes a carbonaceous matrix formed from a fluoropolymer, where lithium fluoride and a nitrate salt are distributed within the carbonaceous matrix. The protective layer further includes residual fluoropolymer and has a first surface adjacent to the electroactive material layer and a second surface opposite to the first surface. A first compositional gradient in the protective layer is defined from the first surface having a first amount of lithium fluoride that is greater than a second amount of lithium fluoride at the second surface, and a second compositional gradient in the protective layer is defined from the first surface having a first amount of residual fluoropolymer that is less than a second amount of residual fluoropolymer at the second surface.