Self-Healing Polymer Coating for Lithium Metal Anodes

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Solution Overview

Problem

Lithium metal anodes in batteries face challenges such as dendrite growth and low Coulombic efficiency due to instability of the solid electrolyte interphase layer, which limits their application in high-energy-density batteries like Li-S and Li-Air.

Innovation Solution

A self-healing polymer with dynamic bonds, such as hydrogen-bonding supramolecular polymers, is applied as a conformal coating on the lithium metal anode, providing a flexible and adaptive layer that heals mechanical damage and maintains uniform lithium deposition even at high current densities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal anode is used to achieve high specific capacity, then energy density is improved, but dendrite growth and low Coulombic efficiency occur due to SEI layer instability

Engineering Contradiction:

Improvespecific capacityVSAvoidCoulombic efficiency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A polymer coating layer is introduced as an intermediary between the lithium metal anode and the electrolyte. This coating acts as a mediator that stabilizes the interface, preventing direct harmful interactions while allowing ionic transport. The polymer layer serves as a protective interface that maintains SEI stability, thereby improving Coulombic efficiency without sacrificing the high specific capacity of lithium metal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin polymer film is applied as a coating on the lithium metal anode surface. This flexible thin film accommodates volume changes during cycling while maintaining structural integrity and preventing dendrite penetration. The film's flexibility allows it to conform to the evolving morphology of lithium deposits, ensuring continuous protection and stable ionic transport pathways.

Inventive Principle:

Principle #30Flexible shells and thin films

2Use of energy by moving object

If lithium metal anode is used to achieve high energy density, then battery capacity is improved, but dendrite formation occurs due to SEI layer instability

Engineering Contradiction:

Improveenergy densityVSAvoiddendrite growth

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The polymer coating serves as an intermediary layer that mediates between the lithium metal and electrolyte, preventing the formation of unstable SEI structures that lead to dendrites. This intermediate layer promotes uniform lithium ion flux distribution, eliminating localized hotspots that would otherwise trigger dendrite nucleation and growth.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The polymer coating is applied beforehand to cushion and protect the lithium metal surface from direct exposure to the electrolyte. This pre-protective layer prevents the formation of unstable SEI structures that would lead to dendrite formation, cushioning the system against future harmful effects before they can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If conventional coating materials are used on lithium anode, then protection is provided, but mechanical damage and pinhole formation reduce effectiveness

Engineering Contradiction:

Improveprotection stabilityVSAvoidmechanical integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The polymer film provides flexible mechanical protection that can accommodate volume changes and stress during cycling without developing pinholes or cracks. The film's viscoelastic properties allow it to absorb mechanical energy and maintain integrity, ensuring continuous protection even under dynamic mechanical conditions.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The polymer coating exhibits dynamic mechanical properties that allow it to adapt to changing conditions during battery operation. The material can reversibly deform and recover, maintaining its protective function under varying mechanical stresses and preventing the formation of permanent defects like pinholes and cracks.

Inventive Principle:

Principle #15Dynamics

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 self-healing polymer coating significantly improves lithium deposition morphology, maintaining high Coulombic efficiency over extended cycles and suppressing dendrite formation, enabling stable and efficient lithium metal anode performance.

Implementation Method 1

self-healing polymer with dynamic bonds... providing a flexible and adaptive layer that heals mechanical damage

Methodology Applied

Scientific EffectSelf-healing:

Implementation Method 2

polymer including dynamic bonds... maintains uniform lithium deposition even at high current densities

Methodology Applied

Scientific EffectDynamic bonding:

Data Source

PatentUS10601049B2High performance battery anodes with polymeric coatings including molecules cross-linked through dynamic bonds

Publication Date: 2020.03.24 THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV

AI summary

A battery includes an anode, a cathode, and an electrolyte disposed between the anode and the cathode. The anode includes a current collector and an interfacial layer disposed over the current collector, and the interfacial layer includes a polymer including dynamic bonds.