Garnet-like Protective Membrane for Lithium Anode Stability

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Solution Overview

Problem

Lithium/air battery cells face challenges in stabilizing the lithium anode in aqueous electrolytes due to corrosion issues with water and oxygen, limiting their energy density and operational efficiency.

Innovation Solution

The development of Li/air battery cells with a protected lithium electrode and an aqueous catholyte in the cathode compartment, which includes an air cathode for oxygen reduction, uses high concentrations of active and non-active salts to render the cathode compartment hygroscopic, maintaining conductivity and preventing dryout, and incorporates a hydrogel or porous reservoir structure to manage water and discharge products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal anode is used in aqueous electrolyte, then high energy density is achieved, but corrosion occurs due to reaction with water and oxygen

Engineering Contradiction:

Improveenergy densityVSAvoidanode stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A protective membrane is introduced as an intermediary layer between the lithium metal anode and the aqueous electrolyte. This membrane allows ion transport while preventing direct contact between lithium and water/oxygen, thus eliminating corrosion while maintaining high energy density benefits

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin protective membrane is applied to the lithium anode surface. This film acts as a barrier that prevents harmful reactions with aqueous electrolyte components while permitting necessary ionic conduction for battery operation

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If protective membrane is added to stabilize lithium anode, then anode stability is improved, but device complexity increases

Engineering Contradiction:

Improveanode stabilityVSAvoidmembrane architecture complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective membrane is divided into multiple functional layers, each with specific properties: one layer interfaces with lithium metal while another interfaces with aqueous electrolyte. This segmentation allows each layer to be optimized for its specific function, managing complexity through functional decomposition

Inventive Principle:

Principle #1Segmentation

3Use of energy by moving object

If high concentration salts are used in cathode compartment, then energy density is improved, but conductivity maintenance becomes challenging

Engineering Contradiction:

Improveenergy densityVSAvoidelectrolyte conductivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The electrolyte composition is optimized by adjusting salt concentrations and selecting specific salt types that maintain high ionic conductivity even at elevated concentrations. Temperature and pH parameters are also controlled to preserve conductivity while achieving high energy density

Inventive Principle:

Principle #35Parameter changes

4Duration of action of moving object

If cathode compartment is made hygroscopic to scavenge water from air, then discharge duration is prolonged, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedischarge durationVSAvoidmembrane interface stability

Core Design Contradiction:

Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

Different regions of the cathode compartment are assigned different properties: the membrane interface region is designed for stability and controlled permeability, while the bulk electrolyte region is made hygroscopic for water scavenging. This local differentiation allows both prolonged discharge and manufacturing feasibility

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 configuration enhances the energy density and prolongs the discharge of Li/air battery cells by scavenging water from ambient air, stabilizing the membrane interface, and accommodating discharge products, thereby improving the overall performance and efficiency of the cells.

Implementation Method 1

protected lithium anodes having protective membranes and protective membrane architectures that are stable in water environments

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

components of the cathode compartment include an air cathode (e.g., oxygen electrode) for the reduction of molecular oxygen

Methodology Applied

Scientific EffectHygroscopic absorption: Absorption (physical)

Implementation Method 3

an air cathode (e.g., oxygen electrode) for the reduction of molecular oxygen

Methodology Applied

Scientific EffectOxygen reduction reaction: Redox Reactions

Implementation Method 4

incorporates a hydrogel or porous reservoir structure to manage water and discharge products

Methodology Applied

Scientific EffectHydrogel absorption: Hydrogel

Data Source

PatentUS9287573B2Lithium battery cell with protective membrane having a garnet like structure

Publication Date: 2016.03.15 POLYPLUS BATTERY CO INC

AI summary

Li/air battery cells are configurable to achieve very high energy density. The cells include a protected a lithium metal or alloy anode and an aqueous catholyte in a cathode compartment. In addition to the aqueous catholyte, components of the cathode compartment include an air cathode (e.g., oxygen electrode) and a variety of other possible elements.