Lithium Metal Negative Electrode Protective Layer for Dendrite Suppression

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Solution Overview

Problem

Lithium metal batteries face issues with dendrite growth and reduced coulombic efficiency, lifespan, and thermal stability due to the high reactivity of lithium metal thin films, leading to deteriorated electrochemical stability.

Innovation Solution

A negative electrode with a protective layer made of an ion-conductive oligomer, which includes ion-conductive structural units and hydrogen-bond forming functional groups, is applied directly to a metal substrate, reducing interfacial resistance and inhibiting dendrite growth while enhancing ionic conductivity and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a lithium metal thin film is used as a negative electrode, then high capacity and fast charging are achieved, but dendrite growth and reduced electrochemical stability occur due to high reactivity with liquid electrode

Engineering Contradiction:

Improvecharging speedVSAvoidelectrochemical stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A protective layer comprising an ion-conductive polymer and a porous layer is introduced as an intermediary between the lithium metal thin film and the liquid electrode. This protective layer acts as a mediator that prevents direct contact and harmful reactions between the lithium metal and liquid electrode, thereby suppressing dendrite growth and improving electrochemical stability while maintaining fast charging capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The negative electrode uses a composite structure combining lithium metal thin film with a protective layer that includes ion-conductive polymer and porous layer. This composite material approach allows the system to benefit from the high capacity of lithium metal while the protective layer components work together to prevent dendrite formation and improve overall electrochemical stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If a protective layer is applied to prevent dendrite growth, then electrochemical stability improves, but interfacial resistance increases

Engineering Contradiction:

Improveelectrochemical stabilityVSAvoidinterfacial resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective layer includes a porous layer with controlled porosity that allows efficient ion transport while maintaining physical protection against dendrites. The porous structure reduces interfacial resistance by providing multiple pathways for ion conduction, preventing the resistance increase that would normally occur with protective coatings

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The protective layer is designed with different regions having different properties: an ion-conductive polymer layer for ionic transport and a porous layer for structural support and dendrite prevention. This local differentiation allows each layer to optimize its function while working together to reduce overall interfacial resistance

Inventive Principle:

Principle #3Local quality

3Strength

If the protective layer thickness is increased to improve mechanical strength, then dendrite prevention improves, but ionic conductivity decreases

Engineering Contradiction:

Improvemechanical strengthVSAvoidionic conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The porous layer provides mechanical strength through its structured framework while maintaining high ionic conductivity through the porous channels. The porosity allows ions to travel efficiently through the layer without requiring excessive thickness, thus maintaining both mechanical protection and ionic transport capability

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The composite structure of ion-conductive polymer and porous layer creates a synergistic effect where the polymer provides ionic conductivity and the porous structure provides mechanical strength. This composite approach allows achieving both goals simultaneously without needing to increase thickness excessively

Inventive Principle:

Principle #40Composite materials

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 solution improves the charging and discharging characteristics, including coulombic efficiency and lifespan, while providing thermal stability and mechanical properties, effectively preventing dendrite growth and enhancing electrodeposition density.

Implementation Method 1

the protective layer includes an ion-conductive oligomer

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

at least two hydrogen-bond forming functional groups at different ends of the ion-conductive oligomer

Methodology Applied

Scientific EffectHydrogen bonding: Van der Waals Force

Data Source

PatentUS10818913B2Negative electrode for metal battery, metal battery comprising the same, and method of preparing the negative electrode for metal battery

Publication Date: 2020.10.27 SAMSUNG ELECTRONICS CO LTD

AI summary

A negative electrode for a metal battery, the negative electrode a metal substrate; and a protective layer disposed directly on at least a portion of the metal substrate, wherein the protective layer comprises an ion-conductive oligomer, wherein the ion-conductive oligomer comprises an ion-conductive structural unit in at least one of a main chain and a side chain of the an ion-conductive oligomer, and at least two hydrogen-bond-forming functional groups at different ends of the ion-conductive oligomer, and wherein the protective layer has a thickness of 5 micrometers or less.