Sulfur-Carbon Composite Cathode for Low-Polarization Solid-State Cells

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Solution Overview

Problem

Lithium ion secondary batteries using sulfur as a positive active material experience significant polarization, which affects their performance.

Innovation Solution

An all-solid-state electrochemical device with a sulfur-carbon composite as the positive active material, where the carbon has an average pore size of 0.5 nm to 3.0 nm and an average particle size of 0.1 μm to 30.0 μm, enhancing electron and ion conduction paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If sulfur is used as the positive active material, then energy density is improved, but polarization increases

Engineering Contradiction:

Improveenergy densityVSAvoidpolarization

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent employs porous carbon materials with specifically controlled pore sizes (0.5-3.0 nm) to accommodate sulfur. The porous structure provides extensive surface area and interconnected pathways that facilitate lithium ion diffusion and electron transport, thereby reducing polarization while maintaining high sulfur content (5% or more by weight) for high energy density.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent creates a sulfur-carbon composite material where sulfur is integrated within a porous carbon matrix. This composite structure combines the high capacity of sulfur with the conductive and structural benefits of porous carbon, achieving both high energy density and reduced polarization through the synergistic interaction between the two materials.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If porous carbon with small pore size is used, then sulfur incorporation is improved, but ion and electron conduction may be hindered

Engineering Contradiction:

Improvesulfur incorporationVSAvoidion and electron conduction

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The patent optimizes the pore size parameter of the porous carbon to a specific range (0.5-3.0 nm) that balances sulfur incorporation efficiency with conduction performance. This parameter optimization ensures sufficient sulfur loading while maintaining adequate pathways for ion and electron transport, resolving the contradiction between sulfur content and conduction ability.

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 sulfur-carbon composite reduces polarization in the all-solid-state electrochemical device, improving charge-discharge characteristics and energy density.

Implementation Method 1

enhancing electron and ion conduction paths

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

enhancing electron and ion conduction paths

Methodology Applied

Scientific EffectElectron conduction: Conduction (electrical)

Data Source

PatentUS20240274793A1All-solid-state electrochemical device and sulfur-carbon composite

Publication Date: 2024.08.15 GS YUASA INT LTD

AI summary

An all-solid-state electrochemical device according to one aspect of the present invention includes: a positive active material layer; an isolation layer; and a negative active material layer, in which the positive active material layer includes a sulfur-carbon composite, the sulfur-carbon composite contains sulfur and porous carbon, and the carbon has an average pore size of 0.5 nm or more and 3.0 nm or less and an average particle size of 0.1 μm or more and 30.0 μm or less.