SWCNT Silicon Anode Composition for Stable Battery Cycle Conductivity

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Solution Overview

Problem

Conventional lithium secondary batteries face challenges in securing sufficient conductivity and maintaining lifespan characteristics due to the use of silicon-based active materials, which experience high volume expansion during charging and discharging, and multi-walled carbon nanotubes fail to maintain conductivity as the cycle progresses.

Innovation Solution

A negative electrode mixture comprising a silicon-based active material and single-walled carbon nanotubes (SWCNT) is formulated, where SWCNTs are added in a specific ratio and shape to connect and cover the surfaces of active material particles, enhancing conductivity and reducing resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multi-walled carbon nanotubes are used as a binder-free active material, then the capacity is improved, but the first charge capacity retention is poor

Engineering Contradiction:

ImprovecapacityVSAvoidfirst charge capacity retention

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The multi-walled carbon nanotubes are segmented into smaller sections along their length through controlled breakdown. This segmentation creates multiple active sites while maintaining the overall tubular structure, improving both capacity and retention by preventing aggregation and enhancing electrolyte access to interior surfaces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The carbon nanotube structure utilizes its inherent porous architecture with controlled inter-tubular spacing. The porous arrangement allows efficient electrolyte penetration and ion transport while maintaining high surface area for lithium insertion, resolving the contradiction between capacity and retention.

Inventive Principle:

Principle #31Porous materials

2Quantity of substance

If the surface area of carbon nanotubes is increased to improve capacity, then the capacity is improved, but the density of the negative electrode is reduced

Engineering Contradiction:

ImprovecapacityVSAvoiddensity of negative electrode

Core Design Contradiction:

Quantity of substanceVSWeight of stationary object

Solution Approach 1:

The carbon nanotubes are arranged in a three-dimensional network structure with controlled orientation and spacing. This dimensional arrangement maximizes surface area for lithium insertion while maintaining compact packing density, effectively decoupling the relationship between surface area and electrode density.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention creates a composite structure where carbon nanotubes are combined with conductive additives and binders in optimized ratios. This composite approach maintains high capacity through increased nanotube surface area while preserving electrode density through efficient material composition and packing.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If conventional mixing and coating methods are used to prepare the negative electrode, then the manufacturing process is simple, but the homogeneity of active material distribution is poor

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidhomogeneity of active material distribution

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The conventional mechanical mixing process is replaced with a slurry-based coating method where carbon nanotubes are dispersed in a liquid medium and applied to the current collector. This substitution enables more uniform distribution while maintaining manufacturing simplicity through standard coating equipment and processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The manufacturing process utilizes parameter optimization including slurry viscosity control, coating speed, and drying temperature to achieve homogeneous active material distribution. By adjusting these parameters, the process maintains simplicity while significantly improving distribution uniformity compared to conventional mixing methods.

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 solution ensures reduced resistance increase and improved lifespan characteristics by maintaining conductivity throughout the battery cycle, with a DCIR growth rate of 47% or less and discharge capacity retention of 91% or more at cycle 100.

Implementation Method 1

single-walled carbon nanotubes which facilitate insertion and extraction of lithium

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 2

a negative electrode for a non-aqueous electrolyte secondary battery, and a method for preparing the same

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentEP4287303B1Negative electrode with single walled carbon nanotube and secondary battery comprising the same

Publication Date: 2026.04.08 LG ENERGY SOLUTION LTD

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AI summary

According to the present embodiment, provided is a negative electrode for a secondary battery which is configured to form a negative electrode mixture on at least one surface of a negative electrode current collector, wherein the negative electrode mixture comprises a negative electrode active material and a conductive material, wherein the negative electrode active material comprises a silicon-based active material, and wherein the conductive material is composed of a single-walled carbon nanotube (SWCNT).