Electrode Mixture Binder Composition for Strong Flexible Sheets

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Solution Overview

Problem

Existing secondary batteries face challenges in achieving higher energy densities and improved battery characteristics while maintaining sufficient strength and flexibility in their electrode structures.

Innovation Solution

Incorporating a tetrafluoroethylene-based polymer composition with a macromolecular compound containing an ionic group as a binder in the electrochemical device mixture, with a specific mass percentage range to enhance binding force and flexibility, allowing for increased active material and conductive aid content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the binder content is increased to improve strength and flexibility, then the mechanical properties of the mixture sheet improve, but the energy density decreases due to higher binder content

Engineering Contradiction:

Improvestrength and flexibility of mixture sheetVSAvoidenergy density

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The invention changes the chemical composition parameters of the binder by incorporating specific fluorinated polymers (polytetrafluoroethylene, polyvinylidene fluoride) with defined molecular weights and compositions. This allows achieving optimal mechanical properties at reduced binder content (3-15 mass%), thereby resolving the contradiction between strength and energy density

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite binder materials combining fluorinated polymers with conductive additives and specific molecular weight distributions. This composite approach enables the binder to provide both mechanical reinforcement and electrical conductivity functions, reducing the required binder amount while maintaining performance

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If more active material and conductive aid are added to increase energy density, then the battery characteristics improve, but the strength and flexibility of the electrode structure deteriorate

Engineering Contradiction:

Improveenergy densityVSAvoidstrength and flexibility of electrode structure

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The invention optimizes the molecular weight parameters of the fluorinated polymer binder (number average molecular weight 10,000-1,000,000) and its composition ratios to achieve maximum binding efficiency. This allows using minimal binder content (3-15 mass%) to maintain electrode structural integrity while maximizing active material content for high energy density

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fluorinated polymer binder acts as an intermediary material that simultaneously provides mechanical binding function and electrical conductivity pathway. This dual-function mediator allows close contact between active material particles while maintaining structural strength, enabling high energy density without sacrificing mechanical properties

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250343240A1Electrochemical device mixture, electrochemical device mixture sheet, electrode, and electrochemical device

Publication Date: 2025.11.06 DAIKIN INDUSTRIES LTD

AI summary

The disclosure provides an electrochemical device mixture capable of providing a mixture sheet exhibiting excellent strength and excellent flexibility while containing a small amount of binder, and an electrochemical device mixture sheet, an electrode, and an electrochemical device each containing the electrochemical device mixture. The electrochemical device mixture contains an electrode active material and/or a solid electrolyte; and a binder. The binder contains a tetrafluoroethylene-based polymer composition. the tetrafluoroethylene-based polymer composition contains a tetrafluoroethylene-based polymer and a macromolecular compound containing an ionic group. The binder is contained in an amount of 0.3% by mass or more and 8% by mass or less relative to the electrochemical device mixture.