Electrode Coating for Lithium-Sulfur Cell Pore Blockage

Solution Overview

Problem

In electrochemical cells, excessive solid formation at unwanted locations leads to pore blockage, reducing system performance and specific energy due to premature end-of-discharge, affecting lithium-sulfur and other electrochemical systems.

Innovation Solution

Employing electrodes with relatively low electronic conductivities, often less than or equal to 200% of the electrolyte's ionic conductivity, and using a ceramic electronic conductivity inhibitor coating to slow down solid precipitation and maintain pore accessibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrodes with high electronic conductivity are used, then electron transport is improved, but solid precipitate formation increases leading to pore blockage

Engineering Contradiction:

Improveelectron transportVSAvoidsolid precipitate formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a dual-conductivity electrode structure where the bulk electrode material maintains high electronic conductivity for efficient electron transport, while the pore surfaces are coated with materials of lower electronic conductivity to suppress unwanted solid precipitate formation. This spatial differentiation of conductivity properties allows simultaneous optimization of both electron transport and precipitate suppression.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining conductive bulk electrode materials (such as carbon or metal foams) with coating materials having controlled electronic conductivity properties. The composite structure integrates the high conductivity needed for electron transport with the lower conductivity surfaces that inhibit solid precipitate formation, resolving the contradiction between these two requirements.

Inventive Principle:

Principle #40Composite materials

2Productivity

If solid precipitates form during discharge, then electrochemical reaction occurs, but pore blockage prevents electrolyte access to active material

Engineering Contradiction:

Improveelectrochemical reaction rateVSAvoidpore accessibility

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent utilizes porous materials with optimized pore size distributions and surface areas to accommodate solid precipitate formation without blocking electrolyte access. The porous structure provides sufficient void space for reaction products while maintaining open pathways for ion transport, thereby sustaining both high reaction productivity and reliable pore accessibility throughout discharge.

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If electrode thickness is increased to提高 energy density, then more active material is available, but solid formation blocks interior pores from electrolyte

Engineering Contradiction:

Improveactive material quantityVSAvoidpore blockage

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a dual-conductivity electrode structure where the bulk electrode material maintains high electronic conductivity for efficient electron transport, while the pore surfaces are coated with materials of lower electronic conductivity to suppress unwanted solid precipitate formation. This spatial differentiation of conductivity properties allows simultaneous optimization of both electron transport and precipitate suppression.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes porous materials with optimized pore size distributions and surface areas to accommodate solid precipitate formation without blocking electrolyte access. The porous structure provides sufficient void space for reaction products while maintaining open pathways for ion transport, thereby sustaining both high reaction productivity and reliable pore accessibility throughout discharge.

Inventive Principle:

Principle #31Porous 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

Inhibits unwanted solid formation, enhances active material utilization, increases specific energy and energy density, and allows for thicker electrodes with higher current densities, improving overall cell performance.

Implementation Method 1

an electronic conductivity inhibitor coating disposed over at least a portion of the electronically conductive material within the porous support structure

Methodology Applied

Scientific EffectElectronic conductivity inhibition: Electrical Resistance

Implementation Method 2

the porous support structure maintains at least a portion of its pore volume

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 3

electrochemical cells comprising electrodes having desirable electronic conductivities and electrolytes having desirable ionic conductivities

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Implementation Method 4

polysulfides such as S2− ions formed during the electrochemical reaction can react with Li+ ions to precipitate as solid Li2S

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Data Source

PatentUS9531009B2Passivation of electrodes in electrochemical cells

Publication Date: 2016.12.27 SION POWER CORP

AI summary

Electrochemical cells having desirable electronic and ionic conductivities, and associated systems and methods, are generally described.