Silicon Anode Nanocomposite Coating for Volume Expansion Control

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Solution Overview

Problem

The use of silicon as a negative electrode active material in lithium-ion batteries is limited by significant swelling and shrinking, leading to reduced energy density and safety concerns, and existing solutions have not effectively addressed these issues.

Innovation Solution

A carbon-based nanocomposite coating liquid is prepared by encapsulating silicon nanoparticles with carbon nanotubes and conductive additives, including a surface treatment and milling process to form a stable electron conduction network, which is then applied to the negative electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon is used as negative electrode active material to increase storage capacity, then theoretical storage capacity increases to 4,200 mAh/g, but volume expansion reaches 310% causing battery swelling and safety issues

Engineering Contradiction:

Improvestorage capacityVSAvoidvolume expansion

Core Design Contradiction:

Quantity of substanceVSShape

Solution Approach 1:

The patent applies nested structure by placing silicon nanoparticles inside carbon-based nanocomposite hollow spheres, creating a core-shell configuration where the carbon shell accommodates the silicon core and its volume expansion, effectively resolving the contradiction between high storage capacity and volume stability

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The carbon-based nanocomposite hollow sphere shell provides a flexible container that can accommodate the 310% volume expansion of silicon during lithiation while maintaining overall structural integrity, preventing battery swelling and safety issues

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If silicon is used as negative electrode active material, then theoretical storage capacity increases to 4,200 mAh/g, but energy density decreases due to volume expansion and cracks

Engineering Contradiction:

Improvestorage capacityVSAvoidenergy density

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent creates a composite material system combining silicon nanoparticles with carbon-based nanocomposite hollow spheres, leveraging the high capacity of silicon while the carbon composite matrix maintains structural stability and prevents energy loss from cracking and volume changes

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If graphite is used as negative electrode active material, then structural stability is improved, but storage capacity is limited to 372 mAh/g

Engineering Contradiction:

Improvestructural stabilityVSAvoidstorage capacity

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The patent changes the fundamental parameter of storage capacity by transitioning from graphite (372 mAh/g) to silicon-based materials (4,200 mAh/g), while using carbon-based nanocomposite hollow spheres to maintain structural stability, thus achieving both high capacity and stability

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If silicon is used as negative electrode active material, then storage capacity increases, but reliability decreases due to separator disruption from battery swelling

Engineering Contradiction:

Improvestorage capacityVSAvoidbattery safety

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The carbon-based nanocomposite hollow sphere shell acts as a flexible containment structure that absorbs the 310% volume expansion of silicon during charging, preventing battery swelling that would otherwise disrupt the separator and compromise safety

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The hollow sphere structure provides pre-designed internal space and structural cushioning to accommodate silicon expansion before it can affect the battery separator, preventing safety issues before they occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 carbon-based nanocomposite coating enhances the energy density and stability of the battery by minimizing volume expansion and maintaining charge-discharge efficiency, resulting in improved capacity and lifespan.

Implementation Method 1

a-2) adding a surface treatment agent to a carbon-based nanomaterial to prepare a surface-treated carbon nanostructure

Methodology Applied

Scientific EffectSurface treatment: Adsorption

Implementation Method 2

a-3) adding the surface-treated carbon nanostructure and a binder to the silicon nanoparticle and then milling the mixture

Methodology Applied

Scientific EffectMilling: Mechanical Force

Implementation Method 3

preparing a composite dispersion including a carbon nanotube and a conductive additive... to form a stable electron conduction network

Methodology Applied

Scientific EffectElectron conduction: Conduction (electrical)

Data Source

PatentUS20250316693A1Method for preparing coating liquid including carbon-based nanocomposite for negative electrode of secondary battery

Publication Date: 2025.10.09 KIM HONG KI

AI summary

A method for preparing a coating liquid for a negative electrode of a secondary battery includes a) preparing a carbon-based nanocomposite, b) preparing a composite dispersion including a carbon nanotube and a conductive additive, and c) mixing the carbon-based nanocomposite in the composite dispersion to prepare a composite coating liquid.