Cross-linked Polysiloxane Separator for Lithium-Air Battery

Solution Overview

Problem

Lithium-air batteries face challenges in preventing dendritic lithium growth, which leads to cell shorting and capacity fade due to the inability of existing separators like LiSICON to effectively inhibit lithium reformation and moisture/air infiltration.

Innovation Solution

A lithium-air battery design incorporating a cross-linked polysiloxane separator that allows lithium ion conductivity while preventing oxygen incursion, either as a standalone membrane or coated on the lithium anode, and potentially laminated with ceramic or other polymers to enhance mechanical strength and prevent dendrite formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If LiSICON is used as separator, then lithium ion conductivity is improved, but dendritic lithium formation is not prevented and the material is fragile and expensive

Engineering Contradiction:

Improvelithium ion conductivityVSAvoiddendrite prevention capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs a composite separator structure consisting of a porous substrate (such as polyolefin or ceramic) coated with a thin film of solid electrolyte material (LiSICON or alternative). This composite approach combines the mechanical strength and porosity of the substrate with the ionic conductivity of the coating, achieving both structural integrity and effective ion transport while preventing dendrite penetration.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent utilizes thin film coatings of solid electrolyte materials on flexible porous substrates. The thin film provides effective dendrite blocking while the flexible porous substrate provides mechanical support and allows for ion transport. This thin film approach reduces material usage and cost while maintaining performance.

Inventive Principle:

Principle #30Flexible shells and thin films

2Use of energy by moving object

If LiSICON is used as separator, then lithium ion conductivity is improved, but the material is fragile and expensive

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidmaterial cost and fragility

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent employs a composite separator structure consisting of a porous substrate (such as polyolefin or ceramic) coated with a thin film of solid electrolyte material (LiSICON or alternative). This composite approach combines the mechanical strength and porosity of the substrate with the ionic conductivity of the coating, achieving both structural integrity and effective ion transport while preventing dendrite penetration.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent explores alternative solid electrolyte materials that are less expensive and more mechanically robust than LiSICON, such as lithium phosphorus oxynitride (LiPON) or polymer-based solid electrolytes. These materials aim to reduce manufacturing cost and improve ease of handling while maintaining adequate ionic conductivity for battery operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Use of energy by moving object

If separator allows lithium ion migration, then electrochemical function is maintained, but oxygen and water incursion is not prevented

Engineering Contradiction:

Improvelithium ion migrationVSAvoidoxygen and water infiltration

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies different functional properties to different regions or aspects of the separator. The separator is designed to be ion-conductive to lithium ions while simultaneously being impermeable to oxygen and water molecules. This is achieved through careful selection of solid electrolyte materials and optimization of pore structure to allow selective transport based on ion size and charge.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs a composite separator structure consisting of a porous substrate (such as polyolefin or ceramic) coated with a thin film of solid electrolyte material (LiSICON or alternative). This composite approach combines the mechanical strength and porosity of the substrate with the ionic conductivity of the coating, achieving both structural integrity and effective ion transport while preventing dendrite penetration.

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 cross-linked polysiloxane separator effectively suppresses lithium dendrite growth, enhances the robustness and cost-effectiveness of lithium-air batteries, and provides a controlled environment for lithium ion transfer, addressing the limitations of traditional LiSICON membranes.

Implementation Method 1

The separator allows for the conductance of lithium ions, while preventing oxygen incursion into the battery

Methodology Applied

Scientific EffectLithium ion conductivity: Conduction (electrical)

Implementation Method 2

The cross-linked polysiloxane separator effectively suppresses lithium dendrite growth

Methodology Applied

Scientific EffectPhysical barrier effect: Physical Containment

Data Source

PatentUS9478782B2Lithium air battery having a cross-linked polysiloxane separator

Publication Date: 2016.10.25 UCHICAGO ARGONNE LLC

AI summary

A lithium-air battery includes a lithium anode; an air cathode; and a separator between the lithium anode and an air cathode the separator including a cross-linked polysiloxane.