Elastomeric Cathode Binder to Reduce Li-Ion Metal Dissolution

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Solution Overview

Problem

Conventional binders used in Li-ion batteries, such as PVDF and PTFE, are brittle and have high fluoride content, leading to mechanical integrity issues and increased metal dissolution, which limits the cycle life of cathodes.

Innovation Solution

A cathode binder comprising elastomeric polyurethane, specifically spandex, with additives like hydrogenated nitrile butadiene rubber (HNBR) to enhance mechanical strength, adhesion, and reduce metal dissolution, while being environmentally benign and cost-effective.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional binders like PVDF and PTFE are used, then the cathode structure is maintained, but the mechanical integrity deteriorates over time due to brittleness and high fluoride content

Engineering Contradiction:

Improvecathode structure stabilityVSAvoidmechanical integrity

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the binder by replacing fluorinated polymers (PVDF, PTFE) with elastomeric polyurethane containing specific functional groups (-NH2, -COOH, -OH). This parameter change transforms the binder from brittle to elastomeric, improving mechanical integrity while maintaining cathode structure stability through the new chemical composition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite binder system using elastomeric polyurethane with specific functional groups that combine adhesive properties with structural stability. The composite nature of the polyurethane, incorporating multiple functional groups, provides both mechanical strength and long-term structural maintenance for the cathode.

Inventive Principle:

Principle #40Composite materials

2Force

If conventional fluorinated binders are used, then adhesion is provided, but metal dissolution increases leading to reduced cycle life

Engineering Contradiction:

ImproveadhesionVSAvoidcycle life

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent extracts and eliminates the harmful fluoride content from the binder composition by replacing PVDF and PTFE with elastomeric polyurethane. This removal of the harmful substance (fluoride) stops the metal dissolution process while retaining the necessary adhesion functionality through the polyurethane's functional groups.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive, harmful fluorinated binders with a more sustainable, environmentally benign elastomeric polyurethane that provides long-term reliability. The new binder material is designed to prevent metal dissolution and extend cycle life, making it a superior alternative despite different cost and environmental characteristics.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Strength

If elastomeric polyurethane is used as binder, then mechanical strength and adhesion are improved, but environmental safety and cost-effectiveness need verification

Engineering Contradiction:

Improvemechanical strengthVSAvoidenvironmental impact

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potential harm of using non-traditional binder materials into a benefit by selecting elastomeric polyurethane that is environmentally benign. The functional groups in the polyurethane (-NH2, -COOH, -OH) provide strong adhesion and mechanical strength while the material itself presents no environmental harm, transforming a potential risk into a sustainable solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20250023051A1Binder for a secondary cell

Publication Date: 2025.01.16 NORTHVOLT AB

AI summary

A binder for a cathode in a secondary cell, wherein the binder comprises an elastomeric polyurethane; a cathode material as well as a cathode comprising said binder; a method to produce said cathode; a secondary cell comprising said cathode; and a vehicle comprising said secondary cell.