Core-Shell Carbon Anode Material for High-Density Roll Pressing

Solution Overview

Problem

Rechargeable lithium batteries face challenges in maintaining structural integrity of the negative electrode active material during roll pressing, which affects the production of high-density electrode plates, leading to reduced capacity and efficiency.

Innovation Solution

A negative electrode active material comprising a core of amorphous carbon surrounded by multiple shells of crystalline and amorphous carbon, with a specific D/G ratio, is used to enhance rollability and electrical conductivity, preventing structural collapse during processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional negative electrode active materials are used during roll pressing, then production efficiency is improved, but structural integrity is lost leading to structural collapse

Engineering Contradiction:

Improveproduction efficiencyVSAvoidstructural integrity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The negative electrode active material uses a composite structure consisting of hard carbon (amorphous) as the core and soft carbon (crystalline) as the shell. This composite structure combines the advantages of both materials: hard carbon provides structural stability and prevents collapse during roll pressing, while soft carbon provides high electrical conductivity and lithium ion insertion/extraction performance. The specific D/G ratio range (1.05-1.30) of the core further optimizes this balance between structural integrity and conductivity.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the negative electrode active material maintains structural integrity during roll pressing, then high-density electrode plates can be produced, but this requires complex core-shell structure fabrication

Engineering Contradiction:

Improveelectrode plate densityVSAvoidstructure fabrication complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The core-shell structure is prepared in advance through a controlled graphitization process. By mixing hard carbon and soft carbon raw materials with specific ratios and performing graphitization at 1000-1500°C for 0.5-5 hours, the desired core structure is formed before electrode assembly. This preliminary preparation ensures that the material has the optimal D/G ratio and structural integrity before being processed into electrode plates, simplifying the overall manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If amorphous carbon is used to prevent structural collapse, then structural stability is improved, but electrical conductivity decreases

Engineering Contradiction:

Improvestructural stabilityVSAvoidelectrical conductivity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The negative electrode active material uses a composite structure consisting of hard carbon (amorphous) as the core and soft carbon (crystalline) as the shell. This composite structure combines the advantages of both materials: hard carbon provides structural stability and prevents collapse during roll pressing, while soft carbon provides high electrical conductivity and lithium ion insertion/extraction performance. The specific D/G ratio range (1.05-1.30) of the core further optimizes this balance between structural integrity and conductivity.

Inventive Principle:

Principle #40Composite 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 proposed structure allows for the production of high-density negative electrodes with improved capacity, efficiency, and quick charging performance by maintaining the core's shape and facilitating lithium ion movement.

Implementation Method 1

a core including a first amorphous carbon and a shell on the core, wherein the shell includes a first shell on the core, with the first shell including a crystalline carbon

Methodology Applied

Scientific EffectAmorphous carbon structure:

Implementation Method 2

a first shell on the core, with the first shell including a crystalline carbon

Methodology Applied

Scientific EffectCrystalline carbon structure:

Implementation Method 3

a ratio of a D/G value of the core to a D/G value of the shell including the first shell and the second shell is about 1.4 to about 15

Methodology Applied

Scientific EffectD/G ratio characterization:

Implementation Method 4

graphitizing the mixture at about 1000 °C to about 1500 °C

Methodology Applied

Scientific EffectGraphitization:

Data Source

PatentEP4657548A1Negative electrode active material, negative electrode including the negative electrode active material, rechargeable lithium battery including the negative electrode, and method of preparing the negative electrode active material

Publication Date: 2025.12.03 SAMSUNG SDI CO LTD

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AI summary

A negative electrode active material includes a core containing a first amorphous carbon and a shell on the core. The shell includes a first shell on the core, with the first shell including a crystalline carbon. The shell also includes a second shell on the first shell, with the second shell including a second amorphous carbon. A ratio of a D/G value of the core to a D/G value of the shell including the first shell and the second shell is about 1.4 to about 15.