Graphene-Selenium Sulfide Composite Electrodes for Lithium Batteries

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium sulfur batteries face challenges due to sulfur's electrical insulating nature, requiring conductive additives like carbonaceous materials, which increase device mass and reduce charge density, and suffer from poor cycle life due to polysulfide migration.

Innovation Solution

Incorporating composites of selenium-sulfur compounds with individual graphene sheets to enhance conductivity and reduce the need for carbonaceous materials, while maintaining or exceeding capacity and improving cycle life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbonaceous material is added to sulfur to improve conductivity, then electrical conductivity is improved, but device mass increases and charge density decreases

Engineering Contradiction:

Improveelectrical conductivityVSAvoiddevice mass

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent uses graphene-sulfur composite materials where sulfur particles are embedded in a graphene matrix. This composite structure provides intrinsic conductivity through the graphene network while maintaining high sulfur content (70-90 wt%) to preserve charge density, resolving the contradiction between conductivity enhancement and mass increase associated with traditional carbonaceous additives.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the conductive material by using reduced graphene oxide with specific properties (high surface area, defect density, and conductivity) rather than traditional carbon black or graphite. This parameter change allows achieving better conductivity with lower mass fraction of conductive material.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If carbonaceous material is added to sulfur to improve conductivity, then electrical conductivity is improved, but apparent charge capacity density decreases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidapparent charge capacity density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The graphene-sulfur composite enables high sulfur loading (70-90 wt%) because the graphene matrix provides sufficient conductivity without adding significant mass. This maintains a high ratio of active material to total electrode mass, preserving apparent charge capacity density while achieving the required conductivity for battery operation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent extracts and removes traditional carbonaceous additives (carbon black, graphite) from the electrode formulation and replaces them with a minimal amount of graphene that serves both as conductive matrix and structural framework, thereby maximizing the fraction of active sulfur material.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If high mass fraction of conductive additive is used to enable high rate charge and discharge, then rate capability is improved, but apparent charge capacity density is reduced

Engineering Contradiction:

Improvecharge and discharge rateVSAvoidapparent charge capacity density

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The graphene-sulfur composite provides superior electrical conductivity and electron transport pathways compared to traditional carbon additives. This intrinsic conductivity of the composite structure enables fast charge and discharge rates without requiring high mass fractions of conductive additive, thus maintaining high apparent charge capacity density.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The porous structure of graphene provides extensive surface area and interconnected pathways for ion and electron transport. This porous architecture facilitates rapid electrochemical reactions at high rates while maintaining a low mass fraction of conductive material, preserving charge capacity density.

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

The selenium-sulfur composite electrodes achieve higher capacity and improved cycle life compared to carbonaceous material-based electrodes, with selenium's higher conductivity supporting better electrical characteristics without decreasing capacity at higher rates.

Implementation Method 1

selenium's higher conductivity supporting better electrical characteristics

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The charge and discharge of the device at high rates

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentUS10177378B2Electrodes incorporating composites of graphene and selenium-sulfur compounds for improved rechargeable lithium batteries

Publication Date: 2019.01.08 VORBECK MATERIALS CORP

AI summary

Embodiments of the present invention relate to battery electrodes incorporating composites of graphene and selenium-sulfur compounds for improved rechargeable batteries. In one embodiment, a conductive composition comprises a conductive composition having a Se—S compound, a conductive additive. The Se—S compound is present as SexS8-x, wherein 0<x<8.