Cellulose Separator Coating for Stronger Sodium-Ion Electrodes

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Solution Overview

Problem

Pure cellulose separators for sodium ion batteries have poor tensile strength, limiting their applicability due to fragility and ease of tearing.

Innovation Solution

A method of forming a cellulose-based separator directly on the electrode active layer of a sodium-ion battery, comprising a nonwoven web of cellulosic fibres, which improves adhesion and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If pure cellulose separators are used in sodium ion batteries, then thermal stability is improved, but tensile strength deteriorates

Engineering Contradiction:

Improvethermal stabilityVSAvoidtensile strength

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent applies composite materials by combining cellulose fibres with other materials (such as polymers or coatings) to create a separator that maintains the thermal stability of cellulose while gaining improved tensile strength from the additional materials. This composite approach allows the separator to withstand mechanical handling stresses without compromising its thermal resistance properties.

Inventive Principle:

Principle #40Composite materials

2Temperature

If pure cellulose separators are used in sodium ion batteries, then thermal stability is improved, but handling performance deteriorates

Engineering Contradiction:

Improvethermal stabilityVSAvoidhandling performance

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The patent uses composite materials to enhance the mechanical properties of cellulose separators, making them more suitable for handling during manufacturing and assembly processes while preserving the excellent thermal stability that makes cellulose an attractive separator material for sodium ion batteries.

Inventive Principle:

Principle #40Composite materials

3Temperature

If pure cellulose separators are used in sodium ion batteries, then thermal stability is improved, but applicability deteriorates

Engineering Contradiction:

Improvethermal stabilityVSAvoidapplicability

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent employs composite materials to create a separator that overcomes the limitations of pure cellulose, thereby expanding the applicability of cellulose-based separators in commercial sodium ion battery applications while maintaining their inherent thermal stability advantages.

Inventive Principle:

Principle #40Composite materials

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 integrated cellulose-based separator enhances the mechanical strength and adhesion to the electrode, addressing the limitations of pure cellulose separators and improving the performance and handling of sodium-ion batteries.

Implementation Method 1

The integrated cellulose-based separator enhances the mechanical strength and adhesion to the electrode

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP4539188A1Separator for a sodium ion cell

Publication Date: 2025.04.16 NORTHVOLT AB

AI summary

The disclosure provides a method of forming a separator on an electrode of a sodium ion cell, and to an electrode/separator composite and to a cell comprising said separator. In particular, the separator is made using methods which dispose a cellulose based separator layer directly onto an electrode.