Sulfur-Carbon Positive Electrode for High-Loading Li-S Batteries

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Solution Overview

Problem

Conventional lithium-sulfur batteries face challenges in achieving high energy density due to the non-conductive nature of sulfur, which reduces reactivity when increasing sulfur content in the positive electrode, hindering commercialization and electrochemical performance.

Innovation Solution

A positive electrode with a sulfur-carbon composite is developed, where sulfur is loaded onto shape-modified porous carbon materials with high porosity and specific particle shape uniformity, enhancing electrical conductivity and sulfur loading, and a lithium-sulfur battery is constructed with a sulfur-carbon composite, binder polymer, and electrolyte to achieve improved energy density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfur content in the positive electrode is increased to achieve high energy density, then energy density is improved, but reactivity is reduced due to the non-conductive nature of sulfur

Engineering Contradiction:

Improveenergy densityVSAvoidreactivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A conductive polymer coating layer is applied to the surface of sulfur particles, serving as an intermediary that provides electrical conductivity while allowing sulfur to maintain its high energy density function. The conductive polymer acts as a mediator between the non-conductive sulfur and the electrochemical reaction environment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The positive electrode uses a composite structure combining sulfur particles with conductive polymer materials. This composite approach allows the electrode to simultaneously achieve high energy density from sulfur and adequate reactivity from the conductive polymer network.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If carbon materials with high specific surface area and high porosity are used as sulfur hosts, then energy density and life characteristics are improved, but additional research and development are needed for commercialization

Engineering Contradiction:

Improveenergy densityVSAvoidcomplexity of sulfur host structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent employs porous carbon materials as sulfur hosts, utilizing their high porosity to accommodate sulfur particles while maintaining structural integrity. The porous structure provides adequate surface area for electrochemical reactions while simplifying the overall electrode design compared to more complex architectures.

Inventive Principle:

Principle #31Porous materials

3Use of energy by moving object

If sulfur is used as the positive electrode active material, then high energy density is achieved, but the non-conductive nature of sulfur reduces reactivity

Engineering Contradiction:

Improveenergy densityVSAvoidelectrochemical reactivity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the surface properties of sulfur particles by coating them with conductive polymers, changing the electrical conductivity parameter without altering the fundamental sulfur structure that provides high energy density.

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 approach results in a lithium-sulfur battery with increased sulfur loading, maintained reactivity, and enhanced energy density, overcoming the limitations of conventional batteries by ensuring high porosity and effective electron transport, thereby improving capacity and stability.

Implementation Method 1

During discharging, the reduction reaction of sulfur and the oxidation reaction of lithium metal occur. In this process, sulfur forms lithium polysulfide (Li2S2, Li2S4, Li2S6, Li2S8) of a linear structure from S8 of a ring structure

Methodology Applied

Scientific EffectReduction reaction: Reduction

Implementation Method 2

During discharging, the reduction reaction of sulfur and the oxidation reaction of lithium metal occur

Methodology Applied

Scientific EffectOxidation reaction: Oxidation

Data Source

PatentUS20240178388A1Positive electrode and lithium-sulfur battery comprising the same

Publication Date: 2024.05.30 LG ENERGY SOLUTION LTD

AI summary

A positive electrode according to the present disclosure includes a current collector; and a positive electrode active material layer on at least one surface of the current collector, wherein the positive electrode active material layer comprises a sulfur-carbon composite and a binder polymer, wherein the sulfur-carbon composite comprises a porous carbon material and a sulfur-based material disposed on at least a portion of an inside of pores and a surface of the porous carbon material, and wherein a ratio of a thickness of the positive electrode (μm) to an amount of carbon per a unit area (1 cm×1 cm) in the positive electrode active material layer (mg) is 80 to 130 (μm/mg).