Oxy-fluoride Surface Modification for Aqueous Cathode Processing

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Solution Overview

Problem

High-voltage, high-capacity lithium metal oxide cathode active materials are challenging to process with water due to their water-reactive surfaces, leading to corrosion of metal current collectors and the need for toxic organic solvents, which increases costs and environmental burden.

Innovation Solution

The surfaces of lithium metal oxide cathode active material particles are modified by forming metal-oxy-fluoride or metal-fluoride bonds through fluorination with agents like LiBF4 or HF, allowing for water-based processing without corrosion and eliminating the need for organic solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If water-based processing is used for lithium metal oxide cathode active materials, then manufacturing cost and environmental burden are reduced, but current collector corrosion and binder agglomeration occur due to high pH

Engineering Contradiction:

Improvemanufacturing costVSAvoidcurrent collector corrosion

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the cathode material surface by introducing fluorine-containing compounds. This modifies the surface chemistry to reduce water reactivity and lower the pH of water-based slurries, preventing current collector corrosion while maintaining the benefits of water-based processing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses fluorine-containing compounds as intermediary substances that coat the cathode material surface. This intermediary layer acts as a barrier that reduces direct water interaction with the cathode material, thereby lowering slurry pH and preventing corrosion of metal current collectors

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If organic solvents are used for processing lithium metal oxide cathode active materials, then current collector corrosion is prevented, but toxic substances are introduced and disposal costs increase

Engineering Contradiction:

Improvecurrent collector corrosionVSAvoidtoxic organic solvents

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent converts the naturally high pH property of water-based slurries (which causes corrosion) into a beneficial feature by using fluorine-containing compounds to lower the pH. This eliminates the need for toxic organic solvents while still preventing current collector corrosion, turning a harmful situation into a beneficial one

Inventive Principle:

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

Solution Approach 2:

The patent replaces expensive and toxic organic solvents with water, which is cheap and environmentally friendly. The fluorine-containing compounds enable this substitution by modifying the slurry chemistry to be compatible with water-based processing

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Use of energy by moving object

If high-voltage, high-capacity lithium metal oxide cathode materials are used, then energy density is increased, but water reactivity increases causing processing problems

Engineering Contradiction:

Improveenergy densityVSAvoidwater reactivity

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies fluorine-containing compounds specifically to the surface of the cathode material particles, creating a localized modification that reduces water reactivity at the surface while preserving the high-voltage, high-capacity properties of the bulk material. This local surface treatment enables water-based processing without sacrificing energy density

Inventive Principle:

Principle #3Local quality

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

This method reduces the pH of water-based slurries, preventing current collector corrosion and binder agglomeration, enabling cost-effective and environmentally friendly manufacturing of lithium battery cells using water instead of organic solvents.

Implementation Method 1

The surfaces of the particles are made of M-oxy-fluoride and/or M-fluoride

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

This method reduces the pH of water-based slurries, preventing current collector corrosion

Methodology Applied

Scientific EffectpH reduction through surface modification:

Data Source

PatentUS11322748B2High-energy cathode material particles with oxy-fluoride surfaces for aqueous processing

Publication Date: 2022.05.03 ROBERT BOSCH GMBH

AI summary

A method of forming a metal oxy-fluoride surface on lithium metal oxide cathode material particles is disclosed. Such a metal oxy-fluoride surface may help to prevent lithium metal oxide cathode active materials from reacting with water, thus enabling aqueous processing of cathodes made from such materials in the manufacture of lithium batteries. Such a method may also reduce lithium battery manufacturing costs and time by substituting water for currently-used organic solvents that are expensive and require special handling and disposal. Such a method may also reduce the cost of lithium metal oxide cathode active materials as the requirements for moisture-free manufacture, storage, and processing will be reduced or eliminated.