Silicon Anode Composite Structure for Expansion-Stable Cycle Life

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Solution Overview

Problem

Rechargeable lithium batteries face challenges with silicon-based negative active materials due to severe volume expansion during charging and discharging, leading to structural breakdown and reduced cycle-life characteristics, particularly when exposed to electrolytes.

Innovation Solution

A negative active material comprising secondary particles of agglomerated silicon particles coated with a ceramic oxide layer and surrounded by amorphous carbon, where the ceramic oxide is discontinuous in the form of islands or dots, with specific thickness and size, and amorphous carbon further includes a second ceramic oxide, enhancing mechanical strength and inhibiting volume expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based negative active material is used, then capacity is improved, but structural stability deteriorates due to severe volume expansion during charging and discharging

Engineering Contradiction:

ImprovecapacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies nested structure by placing silicon particles inside a protective matrix consisting of ceramic oxide and amorphous carbon. The silicon particles are embedded within the ceramic oxide layer, which is further surrounded by amorphous carbon, creating a multi-layer nested structure that accommodates volume expansion while maintaining structural integrity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent uses composite materials by combining silicon with ceramic oxide (such as Al2O3, SiO2, ZrO2) and amorphous carbon to form a composite negative active material. This composite structure leverages the high capacity of silicon while the ceramic oxide and carbon components provide structural stability and resistance to volume expansion.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If silicon particles are exposed to electrolytes, then electrochemical activity is improved, but cycle-life characteristics deteriorate due to structural breakdown

Engineering Contradiction:

Improveelectrochemical activityVSAvoidcycle-life characteristics

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

The patent introduces ceramic oxide and amorphous carbon as intermediary layers between silicon particles and electrolytes. These intermediary materials allow electrochemical reactions to proceed while protecting silicon from direct contact with electrolytes, thereby preventing structural breakdown and improving cycle-life characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The amorphous carbon surrounding the ceramic oxide layer acts as a flexible shell that can accommodate volume changes of silicon particles during charging and discharging. This flexible shell structure maintains structural integrity over multiple cycles while allowing electrochemical activity.

Inventive Principle:

Principle #30Flexible shells and thin films

3Stability of the object's composition

If ceramic oxide coating is applied to suppress volume expansion, then structural stability is improved, but electrical conductivity deteriorates

Engineering Contradiction:

Improvestructural stabilityVSAvoidelectrical conductivity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent creates a composite structure where ceramic oxide particles are embedded in an amorphous carbon matrix. The ceramic oxide provides structural stability and volume expansion control, while the amorphous carbon provides electrical conductivity, achieving a balance between structural stability and electrical conductivity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The amorphous carbon acts as an intermediary material that bridges the electrical conductivity gap created by ceramic oxide coating. It surrounds the ceramic oxide-coated silicon particles and provides conductive pathways, ensuring electrical conductivity is maintained while ceramic oxide provides structural stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively suppresses structural breakdown and improves cycle-life characteristics by minimizing exposure to electrolytes and maintaining electrical conductivity, resulting in enhanced durability and capacity retention.

Implementation Method 1

enhancing mechanical strength and inhibiting volume expansion

Methodology Applied

Scientific EffectMechanical strength enhancement:

Implementation Method 2

maintaining electrical conductivity

Methodology Applied

Scientific EffectElectrical conductivity maintenance:

Implementation Method 3

minimizing exposure to electrolytes

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS12355068B2Negative active material for rechargeable lithium battery, and rechargeable lithium battery including same

Publication Date: 2025.07.08 SAMSUNG SDI CO LTD

AI summary

A negative active material for a rechargeable lithium battery and a rechargeable lithium battery including the same, the negative active material including secondary particles of agglomerated primary particles, the primary particles including Si particles and a first ceramic oxide on a surface of the Si particles; and amorphous carbon, wherein the amorphous carbon surrounds a surface of the primary particles and a surface of the secondary particles.