Alkali Metal-Sulfur Battery Cathode with Expanded Inter-Graphene Spaces

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium-sulfur batteries face issues such as dendrite formation, low electric and ionic conductivity of sulfur, capacity decay due to polysulfide dissolution, and short cycle life, limiting their widespread commercialization and energy density.

Innovation Solution

A rechargeable alkali metal-sulfur battery with a cathode active material layer containing ultra-thin sulfur or ultra-small sulfur particles in a graphite or carbon material with expanded inter-graphene planar spaces, enabling high sulfur utilization efficiency and rate capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfur is used as cathode active material with high theoretical capacity, then energy density is improved, but electric and ionic conductivity deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidelectric and ionic conductivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses composite materials by combining sulfur with conductive carbon matrices (graphite, graphene, carbon nanotubes) to create a cathode that maintains high energy density while improving electric and ionic conductivity. The carbon matrix provides conductive pathways while sulfur provides the high-capacity active material.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs porous carbon structures with controlled pore sizes and high surface areas to accommodate sulfur. The porous structure increases the contact area between sulfur and conductive additives, improving ionic and electric conductivity while maintaining high sulfur loading for energy density.

Inventive Principle:

Principle #31Porous materials

2Ease of manufacture

If conventional sulfur cathode structure is used, then manufacturing is simplified, but capacity decay due to polysulfide dissolution increases

Engineering Contradiction:

Improvecathode structure simplicityVSAvoidcycle life

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent uses thin film coatings of conductive materials on carbon structures to encapsulate sulfur and prevent polysulfide dissolution. The thin film barrier prevents harmful interactions while maintaining the simplicity of the overall cathode manufacturing process.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent introduces conductive carbon matrices and surface coatings as intermediary materials between sulfur and the electrolyte. These intermediaries prevent direct contact between polysulfides and the electrolyte, reducing dissolution and capacity decay while maintaining ease of manufacture through standard coating and assembly processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If sulfur particles are made ultra-thin or ultra-small to improve rate capability, then power density is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improverate capabilityVSAvoidsulfur particle size control

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The patent changes the physical parameters of sulfur by reducing particle size to ultra-thin or ultra-small dimensions and controlling morphology. This increases the surface area to volume ratio, improving rate capability and power density while the conductive matrix compensates for the increased manufacturing complexity.

Inventive Principle:

Principle #35Parameter changes

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 solution achieves a high specific energy density, long cycle life, and reduced dendrite formation, overcoming the limitations of conventional lithium-sulfur batteries by maintaining intimate contact between sulfur and conductive additives and trapping sulfur within expanded interstitial spaces.

Implementation Method 1

Methodology Applied

Scientific EffectPhysical containment in expanded interstitial spaces: Physical Containment

Implementation Method 2

an electrolyte with an optional porous separator layer in ionic contact with the anode active material layer and the cathode active material layer

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS10651464B2Alkali metal-sulfur secondary battery containing a nano sulfur-loaded cathode and manufacturing method

Publication Date: 2020.05.12 HONEYCOMB BATTERY CO

AI summary

A rechargeable alkali metal-sulfur cell selected from lithium-sulfur cell, sodium-sulfur cell, or potassium-sulfur cell The alkali metal-sulfur cell comprises an anode active material layer, an optional anode current collector supporting the anode active material layer, a cathode active material layer, an electrolyte with an optional porous separator layer in ionic contact with the anode active material layer and the cathode active material layer, and an optional cathode current collector supporting the cathode active material layer, wherein the cathode active material layer contains a graphite or carbon material having expanded inter-graphene planar spaces with an inter-planar spacing d002 from 0.43 nm to 2.0 nm, as measured by X-ray diffraction, and 1%-95% by weight of sulfur or a metal polysulfide residing in these expanded inter-graphene planar spaces. This battery exhibits an excellent combination of high sulfur content, high sulfur utilization efficiency, high energy density, and long cycle life.