Lithium Battery Negative Electrode Drying for Binder Uniformity

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Solution Overview

Problem

High loading designs for lithium secondary battery electrodes face limitations due to binder migration during the drying process, leading to non-uniform distribution, reduced adhesion, and increased interfacial resistance, which degrade cycle characteristics and charging performance.

Innovation Solution

A method involving a multilayer structure for the negative electrode active material, where each layer has distinct drying conditions, with a higher drying rate and temperature for the lower layer and a lower rate and temperature for the upper layer, to prevent binder migration and ensure uniform distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a high loading design is used to increase the amount of active material in the electrode, then the energy density is improved, but the binder migrates during drying leading to non-uniform distribution and increased interfacial resistance

Engineering Contradiction:

Improveamount of active materialVSAvoiduniformity of binder distribution

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The electrode is divided into multiple layers, with each layer containing a portion of the binder. This segmentation prevents binder migration within each individual layer while maintaining high overall active material loading, thus resolving the contradiction between quantity and uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electrode (different layers) are assigned different binder amounts optimized for their specific positions. This local optimization ensures uniform binder distribution throughout the entire electrode structure while maintaining high overall loading, addressing the contradiction between quantity and precision.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If a high loading design is used to increase the amount of active material in the electrode, then the energy density is improved, but the adhesion between active material and current collector is reduced

Engineering Contradiction:

Improveamount of active materialVSAvoidadhesion between active material and current collector

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The electrode structure is segmented into multiple layers, each with controlled binder content. This ensures sufficient adhesion strength at each interface between active material and current collector, preventing the adhesion loss that occurs in high-loading single-layer designs.

Inventive Principle:

Principle #1Segmentation

3Quantity of substance

If a high loading design is used to increase the amount of active material in the electrode, then the energy density is improved, but the interfacial resistance of the negative electrode is increased

Engineering Contradiction:

Improveamount of active materialVSAvoidinterfacial resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Dividing the electrode into multiple layers with controlled binder distribution reduces interfacial resistance by ensuring proper contact and adhesion at each interface, thereby maintaining reliability despite high overall loading.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Optimizing binder content locally in different layers ensures that each region has appropriate interfacial properties, reducing overall interfacial resistance while maintaining high active material loading throughout the electrode.

Inventive Principle:

Principle #3Local quality

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

This approach enhances adhesion between the active material and current collector, improves charging characteristics by reducing interfacial resistance, and extends battery life by maintaining consistent conductivity and structural stability.

Implementation Method 1

a lower negative electrode active material layer facing the current collector is dried at a higher drying rate

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

the lower negative electrode active material layer is dried at a higher drying rate and temperature

Methodology Applied

Scientific EffectThermal energy transfer: Heating

Implementation Method 3

an upper negative electrode active material layer is dried at a lower drying rate

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 4

the upper negative electrode active material layer is dried at a lower temperature

Methodology Applied

Scientific EffectThermal energy transfer: Heating

Data Source

PatentEP3335260B1Method of preparing electrode for lithium secondary battery and electrode for lithium secondary battery prepared thereby

Publication Date: 2023.08.30 LG ENERGY SOLUTION LTD

Figure 1a~2
Figure 3~4

AI summary

The present invention relates to a method of preparing an electrode for a lithium secondary battery and an electrode for a lithium secondary battery prepared thereby, wherein, since the method may suppress the migration of a binder and may uniformly control the distribution of the binder in the electrode by forming a plurality of negative electrode active material layers and allowing a drying condition of each of the negative electrode active material layers to be different, the method may improve life characteristics by improving adhesion between a negative electrode active material and a current collector and may improve charging characteristics by reducing interfacial resistance of the negative electrode.