Rubber-Based Binder Controls Cracking in High-Rate Rolled Lithium Battery Electrodes

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Solution Overview

Problem

Lithium secondary batteries face issues with crack development, internal short circuits, high voltage defects, and capacity decline due to increased rolling rates, which are linked to the rigidity of the positive electrode active material layer, necessitating a method to enhance the flexibility and rolling properties of this layer.

Innovation Solution

Incorporating a rubber-based binder in a specific ratio within the positive electrode active material slurry, along with a fluorine-based binder, to control the degree of non-crystallinity, thereby improving the flexibility and rolling properties of the positive electrode active material layer, and using a consecutive mixing method to enhance dispersibility and prevent conductor tangling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rolling rate is increased to improve productivity, then the manufacturing efficiency is improved, but cracks are developed in the positive electrode causing reliability deterioration

Engineering Contradiction:

Improverolling rateVSAvoidcrack development

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the binder by incorporating rubber-based binder (20-70 wt%) combined with fluorine-based binder, creating a composite binder system that modifies the mechanical properties of the positive electrode active material layer to resist cracking during high-speed rolling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite binder system combining rubber-based binder and fluorine-based binder in specific ratios, creating a material with enhanced flexibility and adhesion properties that prevents crack formation while maintaining structural integrity during high-rate rolling processes

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the thickness of the positive electrode is increased to improve capacity, then the energy density is improved, but the flexibility and rolling properties deteriorate

Engineering Contradiction:

Improvepositive electrode active material loadingVSAvoidflexibility and rolling properties

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The patent modifies the binder composition parameters to include rubber-based binder (20-70 wt%) which provides enhanced flexibility and adhesion, allowing the positive electrode active material layer to maintain good rolling properties even at increased thickness and higher active material loading

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10680247B2Positive electrode active material slurry including rubber-based binder and positive electrode prepared therefrom

Publication Date: 2020.06.09 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to positive electrode active material slurry of which degree of non-crystallinity is controlled by including a rubber-based binder in a specific ratio, a positive electrode including a positive electrode active material layer formed therefrom, and a lithium secondary battery including the positive electrode. The positive electrode active material layer formed from the positive electrode active material slurry has enhanced flexibility and rolling property, and internal short circuits, high voltage defects and capacity decline of the lithium secondary battery using the positive electrode including the same are capable of being suppressed.