Mesoporous Silicon-Carbon Anode Material for Longer Battery Cycle Life

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Solution Overview

Problem

Existing rechargeable lithium batteries face challenges in achieving high capacity, high efficiency, and excellent cycle-life characteristics due to issues with volume expansion of silicon-based negative active materials during charging and discharging.

Innovation Solution

A negative active material is developed comprising a porous support with mesopores, a carbon layer, a silicon layer, and an amorphous carbon layer, prepared through vapor coating processes to control silicon deposition and minimize volume expansion, enhancing ionic conductivity and cycle-life characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based negative active material is used to increase capacity, then battery capacity is improved, but volume expansion occurs during charging and discharging leading to poor cycle-life

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle-life characteristic

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The negative active material is segmented into a composite structure consisting of silicon particles embedded in a carbon matrix, rather than using bulk silicon. This segmentation into discrete phases (silicon domains and carbon matrix) allows the silicon to expand and contract locally without compromising the overall electrode structure, thereby maintaining capacity while improving cycle-life

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A composite material system is employed combining silicon and carbon in a specific architecture where silicon particles are dispersed within a conductive carbon matrix. This composite structure leverages the high capacity of silicon while the carbon component provides structural stability and electrical conductivity, resolving the contradiction between capacity and cycle-life

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silicon layer is added to increase capacity, then battery capacity is improved, but structural stability deteriorates due to volume expansion

Engineering Contradiction:

Improvebattery capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

A carbon matrix acts as a flexible confining medium surrounding silicon particles. This carbon shell/matrix structure can accommodate the volume changes of silicon during lithiation and delithiation, providing mechanical stability while allowing the necessary expansion, thus maintaining both capacity and structural integrity

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The carbon matrix serves as an intermediary between the silicon particles and the electrolyte, and also as a mechanical buffer between expanding silicon particles. This intermediary carbon phase mediates the stress and strain during cycling, preventing direct structural degradation of the silicon and maintaining overall compositional stability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional coating methods are used, then manufacturing simplicity is maintained, but control over silicon deposition and volume expansion is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidsilicon deposition control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Conventional mechanical coating methods are replaced with chemical vapor deposition (CVD) processes. This substitution allows precise control over silicon layer deposition through chemical reactions in the vapor phase, enabling better control of deposition thickness and uniformity while maintaining a relatively simple continuous manufacturing process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in a negative active material with improved charge and discharge efficiency, high-rate characteristics, and extended cycle-life, suitable for high-capacity rechargeable lithium batteries.

Implementation Method 1

a porous support with mesopores, a carbon layer, a silicon layer, and an amorphous carbon layer

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

prepared through vapor coating processes to control silicon deposition

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Data Source

PatentUS20250323251A1Negative active material, method of preparing negative active material, negative electrode including negative active material, and rechargeable lithium battery including negative active material

Publication Date: 2025.10.16 SAMSUNG SDI CO LTD

AI summary

Disclosed are a negative active material, a method of preparing the negative active material, and a rechargeable lithium battery including the negative active material. The negative active material includes a core comprising a porous support comprising pores, a carbon layer provided in the pores, a silicon layer provided on the carbon layer, and an amorphous carbon layer provided on an outer surface of the core. The pores comprise mesopores that are about 50% to about 100% of a total porosity of the porous support.