CNT Binder Cathodes for Fluorine-Free High-Density Li-Ion Cells

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Solution Overview

Problem

There is a need for lithium ion batteries with high volumetric energy density that do not include environmentally harmful elements such as fluorine atoms, and existing cathodes require non-CNT binders and additional carbon sources.

Innovation Solution

The use of single-wall and double-wall carbon nanotubes (SW-CNTs and DW-CNTs) as binders without the need for non-CNT binders or additional carbon sources, combined with conductive carbon and polar adhesives, to form cathodes with high active material content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional non-CNT binders and additional carbon sources are used in cathodes, then cathode structure stability and conductivity are maintained, but volumetric energy density decreases and environmentally harmful elements are introduced

Engineering Contradiction:

Improvevolumetric energy densityVSAvoidenvironmentally harmful elements (fluorine atoms)

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes non-CNT binders and additional carbon sources from the cathode composition, retaining only CNT binders. This extraction eliminates environmentally harmful fluorine atoms associated with conventional binders like PVDF while maintaining cathode structure stability through the unique properties of carbon nanotubes.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the binder material parameter from conventional non-CNT binders (such as PVDF containing fluorine) to CNT-based binders. This parameter change eliminates harmful fluorine elements while improving volumetric energy density through the high aspect ratio and conductive properties of carbon nanotubes.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If non-CNT binders are used in cathodes, then cathode structure stability is maintained, but volumetric energy density and environmental friendliness deteriorate

Engineering Contradiction:

Improvecathode structure stabilityVSAvoidvolumetric energy density

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The CNT binder performs multiple functions simultaneously: it provides structural stability to maintain cathode integrity, enhances electrical conductivity through its conductive network, and eliminates the need for additional carbon sources. This multi-functionality achieves structure stability without compromising volumetric energy density.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses carbon nanotubes as a composite binder material that combines the structural stability function of traditional binders with enhanced conductivity and space efficiency. The CNT composite structure provides mechanical support while occupying minimal volume, thereby maintaining stability without reducing volumetric energy density.

Inventive Principle:

Principle #40Composite materials

3Reliability

If non-CNT binders and additional carbon sources are added to cathodes, then cathode performance is maintained, but device complexity and manufacturing complexity increase

Engineering Contradiction:

Improvecathode performanceVSAvoidcathode composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of binders and carbon sources into a single CNT binder component. Instead of using separate non-CNT binders and additional carbon sources, the CNT material simultaneously provides binding, structural support, and conductivity, thereby simplifying cathode composition while maintaining performance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The CNT binder serves as a universal material that replaces multiple components (non-CNT binders and carbon sources). Its ability to perform binding, provide structural stability, and enhance conductivity in a single material reduces cathode composition complexity and simplifies manufacturing processes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 SW-CNT and DW-CNT cathodes achieve higher volumetric energy density and improved tensile strength, thermal conductivity, and conductivity without the use of non-CNT binders, while maintaining comparable performance to conventional cathodes.

Implementation Method 1

single-wall carbon nanotubes (SW-CNTs) and/or double-wall carbon nanotubes (DW-CNTs) as binders

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

conductive carbon includes graphite, carbon black, multi-walled CNT

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

improved tensile strength, thermal conductivity, and conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250343236A1Single wall and double wall carbon nanotube containing cathodes

Publication Date: 2025.11.06 APPLE INC

AI summary

The disclosure relates generally to batteries, and more particularly, cathodes having a single-wall carbon nanotube (SW-CNT) and/or double-wall carbon nanotube (DW-CNT) binders for use in lithium ion battery cells.