Core-Shell Sulfur Cathode Composites for Polysulfide Containment

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Solution Overview

Problem

Conventional sulfur-based cathodes in metal-ion batteries face challenges with low electrical and ionic conductivity, as well as physical instability, which hinder their practical application due to issues like sulfur dissolution and polysulfide precipitation.

Innovation Solution

The development of core-shell composites comprising a sulfur-based core encased in a multi-functional shell that is permeable to metal ions but impermeable to electrolyte solvent molecules and polysulfides, enhancing electrical and ionic conductivity while maintaining structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfur-based cathodes are used to achieve high specific capacity, then energy density is improved, but electrical conductivity deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidelectrical conductivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs a core-shell composite structure where sulfur-based active material forms the core and a conductive shell material envelops it. This composite architecture combines the high capacity advantage of sulfur with the electrical conductivity of the shell material, resolving the contradiction between energy density and conductivity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The conductive shell acts as a flexible coating that conforms to the sulfur core surface, providing continuous electrical pathways while maintaining the high surface area-to-volume ratio needed for high capacity. The thin film structure minimizes resistance without compromising conductivity.

Inventive Principle:

Principle #30Flexible shells and thin films

2Use of energy by moving object

If sulfur-based cathodes are used to achieve high specific capacity, then energy density is improved, but structural stability deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The core-shell composite structure provides mechanical support to the sulfur core, preventing structural collapse during volume changes. The shell acts as a reinforcing framework that maintains structural integrity while allowing the high-capacity sulfur material to function.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The shell material is strategically positioned at the surface of the sulfur particles, providing localized mechanical support where it is most needed during electrochemical cycling. This localized reinforcement prevents catastrophic structural failure while preserving the bulk sulfur capacity.

Inventive Principle:

Principle #3Local quality

3Use of energy by moving object

If sulfur-based cathodes are used to achieve high specific capacity, then energy density is improved, but ionic conductivity deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidionic conductivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The conductive shell material provides pathways for ion transport that complement the sulfur core's electrochemical activity. The composite structure creates multiple conduits for ionic movement, enhancing overall ionic conductivity while maintaining high capacity.

Inventive Principle:

Principle #40Composite materials

4Use of energy by moving object

If sulfur-based cathodes are used to achieve high specific capacity, then energy density is improved, but reversibility deteriorates due to polysulfide dissolution

Engineering Contradiction:

Improveenergy densityVSAvoidelectrochemical reversibility

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The conductive shell extracts or removes polysulfides from the electrolyte environment by providing alternative accommodation sites within the shell structure. This prevents polysulfide dissolution into the bulk electrolyte, maintaining electrochemical reversibility while preserving sulfur's high capacity.

Inventive Principle:

Principle #2Taking out (Extraction)

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 design significantly improves the stability and performance of sulfur-based cathodes by reducing sulfur dissolution and enhancing electrochemical reversibility, leading to higher energy density and longer cycle life in metal-ion batteries.

Implementation Method 1

a multi-functional shell that is permeable to metal ions

Methodology Applied

Scientific EffectPermeation: Permeation

Implementation Method 2

substantially impermeable to electrolyte solvent molecules and polysulfides

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 3

enhancing electrical and ionic conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

enhancing electrical and ionic conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 5

electrochemically react with metal ions during battery operation to store the metal ions

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentUS11843114B2Core-shell composites for electrodes in metal-ion batteries

Publication Date: 2023.12.12 SILA NANOTECHNOLOGIES INC

AI summary

A battery electrode composition is provided comprising core-shell composites. Each of the composites may comprise a core and a multi-functional shell.