Battery Negative Electrode Coating for Crack-Free Cutting

Solution Overview

Problem

The existing manufacturing process for negative electrodes in secondary batteries often results in cracks and peeling off of the active material layer during cutting, leading to performance deterioration and safety issues.

Innovation Solution

A negative electrode with a continuous adhesive force of 30 gf/20 mm or more and a breaking stress of 3.6 N or more is achieved by forming a negative electrode active material layer on a current collector with a binder content of 2% by weight or more and porosity of 28% or less, and through controlled misfit strain during drying and rolling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the negative electrode active material layer is applied onto the current collector using conventional manufacturing processes, then the battery production can proceed, but cracks and peeling off occur during cutting due to insufficient adhesive force and breaking stress

Engineering Contradiction:

Improveadhesive forceVSAvoidcutting process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the binder content (2-10 wt% based on total slurry weight) and controlling the porosity (20-40%) of the negative electrode active material layer. These parameter adjustments enhance the continuous adhesive force (≥30 gf/20mm) and breaking stress (≥3.6 N), preventing cracks and peeling during cutting while maintaining manufacturability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by formulating a slurry comprising negative electrode active material, binder, and conductive material in specific proportions. This composite structure provides both the necessary electrical conductivity and mechanical strength, ensuring the layer withstands cutting forces without defect formation

Inventive Principle:

Principle #40Composite materials

2Reliability

If the negative electrode active material layer is applied onto the current collector using conventional manufacturing processes, then the battery production can proceed, but cracks and peeling off occur during cutting due to insufficient breaking stress

Engineering Contradiction:

Improvebreaking stressVSAvoidcutting process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the binder content (2-10 wt% based on total slurry weight) and controlling the porosity (20-40%) of the negative electrode active material layer. These parameter adjustments enhance the continuous adhesive force (≥30 gf/20mm) and breaking stress (≥3.6 N), preventing cracks and peeling during cutting while maintaining manufacturability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by formulating a slurry comprising negative electrode active material, binder, and conductive material in specific proportions. This composite structure provides both the necessary electrical conductivity and mechanical strength, ensuring the layer withstands cutting forces without defect formation

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

Prevents cracks and peeling off of the negative electrode active material layer during cutting, thereby enhancing the stability and safety of secondary batteries.

Implementation Method 1

the continuous adhesive force in the thickness direction of the negative electrode for secondary battery is 30 gf/20 mm or more

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20230387382A1Negative Electrode For Secondary Battery, Manufacturing Method Thereof, and Secondary Battery Comprising the Same

Publication Date: 2023.11.30 LG ENERGY SOLUTION LTD

AI summary

A negative electrode for a secondary battery in which a negative electrode active material layer is formed on at least one surface of a current collector.The continuous adhesive force in the thickness direction of the negative electrode for the secondary battery is 30 gf/20 mm or more, and/orthe breaking stress of the negative electrode is 3.6 N or more. The breaking stress is a value measured by pressing the negative electrode active material layer with a linear tip having a width of 2.5 mm and a sharp end at a speed of 10 μm/s.