Fluoride Coating on Electrode Materials for Battery Stability

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Solution Overview

Problem

Lithium ion batteries face irreversible capacity losses due to corrosion and electrolyte decomposition, primarily caused by hydrofluoric acid attacking electrode materials, and surface carbonates formed during processing degrade battery performance, making it challenging to achieve stable and efficient electrochemical performance.

Innovation Solution

A method involving precursor vapor phase synthesis or atomic layer deposition to form a fluoride coating on electrode materials, specifically a LiF coating, which stabilizes the electrode surface, prevents hydrofluoric acid attack, and enhances ionic conductivity, while also reducing surface carbonate formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If electrode materials are used to deliver high energies and capacities, then battery performance is improved, but cathode-surface reactions, oxygen activity, and transition metal dissolution occur causing instability

Engineering Contradiction:

Improvebattery energy and capacityVSAvoidinterface stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

A fluoride coating layer is deposited on the cathode surface before battery assembly and operation. This preliminary protective layer prevents harmful cathode-surface reactions, oxygen loss, and transition metal dissolution that would otherwise occur during battery cycling, thereby maintaining both high performance and interface stability throughout battery operation.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If surface carbonates are present on electrode materials, then processing is simplified, but battery performance degrades due to corrosion and electrolyte decomposition

Engineering Contradiction:

Improveprocessing simplicityVSAvoidbattery performance stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Instead of completely removing surface carbonates formed during processing, the invention converts this potentially harmful byproduct into a beneficial component by depositing a fluoride coating layer over the carbonate surface. This fluoride layer protects the underlying carbonate and electrode material from corrosion and prevents electrolyte decomposition, thereby improving long-term performance stability while accepting the simplified processing approach.

Inventive Principle:

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

3Manufacturing precision

If conventional coating methods are used, then coating can be applied, but uniform deposition and scalability are limited

Engineering Contradiction:

Improvecoating uniformityVSAvoidscalability

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The invention employs a vapor-phase deposition process where fluoride precursor materials are delivered as vapors that uniformly coat the cathode surface through gas flow dynamics. This pneumatic approach enables consistent and uniform fluoride layer deposition across large-scale electrode surfaces, significantly improving both coating uniformity and manufacturing scalability compared to conventional liquid or contact-based coating methods.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 LiF coating improves the long-term cycling stability and efficiency of lithium ion batteries by preventing transition metal dissolution and electrolyte decomposition, maintaining performance even after exposure to atmospheric conditions, and allowing for scalable and uniform deposition at low temperatures.

Implementation Method 1

surface modification of a surface carbonate using precursor vapor phase synthesis or atomic layer deposition so as to form fluoride coatings on electrode materials

Methodology Applied

Scientific EffectVapor phase synthesis: Chemical Vapour Deposition

Implementation Method 2

surface modification of a surface carbonate using precursor vapor phase synthesis or atomic layer deposition so as to form fluoride coatings on electrode materials

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Implementation Method 3

the fluoride-based precursor material dopes the surface carbonate so as to form a layer of a fluoride coating on the electrode material

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS20220293900A1Methods for coating electrode materials with fluoride coating and electrodes formed therefrom

Publication Date: 2022.09.15 UCHICAGO ARGONNE LLC

AI summary

A process for forming a fluoride-based coating on an electrode material that is at least partially covered with a surface carbonate, includes disposing the electrode material in a reactor. The electrode material is exposed to a vapor of a fluoride-based precursor material such that the fluoride-based precursor material dopes the surface carbonate so as to form a layer of a fluoride coating on the electrode material.