Graphene Protective Coating for Lithium Electrodes

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Solution Overview

Problem

Lithium-containing electrodes in electrochemical cells face issues with lithium dendrite growth and mossy lithium formation, which reduce cycle efficiency and increase overpotential, and existing methods often rely on costly and environmentally unfriendly wet chemistry techniques.

Innovation Solution

A protective coating comprising graphene is applied to the lithium-containing electrodes, removing passivation layers and preventing lithium dendrite growth through non-covalent interactions, while also accommodating volume changes during cycling, and this coating is formed simultaneously with the removal of passivation layers using a graphene source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective coating is applied to prevent lithium dendrite growth, then cycle efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecycle efficiencyVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies a thin film protective coating comprising graphene or few-layer graphene onto the lithium-containing electrode surface. This thin film structure prevents lithium dendrite growth and mossy lithium formation while maintaining flexibility to accommodate volume changes during cycling, thereby improving cycle efficiency without requiring complex manufacturing processes

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective coating is formed by combining a graphene source material with the electrode surface, creating a composite structure where graphene provides protective functionality. This composite approach enables the coating to prevent dendrite growth while remaining compatible with existing electrode manufacturing processes

Inventive Principle:

Principle #40Composite materials

2Reliability

If wet chemistry techniques are used to form protective coatings, then coating formation is effective, but environmental friendliness and cost are worsened

Engineering Contradiction:

Improvecoating formation effectivenessVSAvoidenvironmental friendliness

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces traditional wet chemistry techniques with a mechanical/physical approach where a graphene source is directly applied and transferred to the electrode surface. This substitution eliminates the need for harmful chemical solutions and complex wet chemistry processing steps, forming an effective protective coating through physical mechanisms alone

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The method uses a disposable graphene source that can be directly applied to the electrode surface without requiring expensive, environmentally harmful chemical reagents. The graphene source serves its purpose of transferring graphene to form the protective coating and can be discarded after use, eliminating waste treatment requirements

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If the protective coating is too thick, then dendrite prevention is improved, but volume change accommodation is reduced

Engineering Contradiction:

Improvedendrite preventionVSAvoidvolume change accommodation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent specifies that the protective coating comprises graphene or few-layer graphene with controlled thickness. The thin film structure provides sufficient barrier properties to prevent dendrite growth while maintaining the flexibility and mechanical compliance needed to accommodate volume changes of the underlying electrode material during charging and cycling

Inventive Principle:

Principle #30Flexible shells and thin films

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 graphene protective coating enhances cycle efficiency, reduces overpotential, and improves performance by preventing lithium dendrite growth and mossy lithium formation, while avoiding the drawbacks of traditional wet chemistry methods.

Implementation Method 1

removing a passivation layer present on the first Li-containing surface of the electrode by applying a graphene source to the first Li-containing surface of the electrode

Methodology Applied

Scientific EffectNon-covalent interactions: Van der Waals Force

Implementation Method 2

preventing lithium dendrite growth through non-covalent interactions

Methodology Applied

Scientific EffectNon-covalent interactions: Van der Waals Force

Data Source

PatentUS11063248B2Protective coating for lithium-containing electrode and methods of making the same

Publication Date: 2021.07.13 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods of removing a passivation layer on a lithium-containing electrode and preparing a protective coating on the lithium-containing electrode by applying a graphene source are provided herein. A lithium-containing electrode with the protective coating including graphene and lithium-containing electrochemical cells including the same are also provided herein.