Negative Electrode Tg Gradient for Adhesion and Electrolyte Permeability

Solution Overview

Problem

Conventional non-aqueous electrolyte secondary batteries face challenges in achieving both good output characteristics and charge-discharge cycle characteristics due to issues with adhesiveness and permeability of the negative electrode active material layer.

Innovation Solution

A negative electrode for non-aqueous electrolyte secondary batteries is designed with a negative electrode active material layer that includes styrene-butadiene rubber, where the rubber in a 10% region near the current collector has a lower glass transition temperature for enhanced adhesiveness, and in a 10% region near the opposite surface has a higher glass transition temperature to reduce occlusiveness and enhance electrolyte permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If styrene-butadiene rubber with low glass transition temperature is used to enhance adhesiveness, then charge-discharge cycle characteristics improve, but electrolyte permeability decreases

Engineering Contradiction:

Improvecharge-discharge cycle characteristicsVSAvoidelectrolyte permeability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating a gradient structure where the glass transition temperature of styrene-butadiene rubber varies through the thickness of the active material layer. The region near the current collector uses lower Tg rubber for adhesion, while the outer region uses higher Tg rubber for permeability, allowing each zone to optimize its local function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of glass transition temperature spatially within the active material layer. By controlling the Tg distribution (lower near current collector, higher at outer surface), the patent simultaneously achieves good adhesiveness and electrolyte permeability, resolving the contradiction between these two properties.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If styrene-butadiene rubber with high glass transition temperature is used to enhance electrolyte permeability, then output characteristics improve, but adhesiveness decreases

Engineering Contradiction:

Improveoutput characteristicsVSAvoidadhesiveness

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies local quality by creating a gradient structure where the glass transition temperature of styrene-butadiene rubber varies through the thickness of the active material layer. The region near the current collector uses lower Tg rubber for adhesion, while the outer region uses higher Tg rubber for permeability, allowing each zone to optimize its local function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of glass transition temperature spatially within the active material layer. By controlling the Tg distribution (lower near current collector, higher at outer surface), the patent simultaneously achieves good adhesiveness and electrolyte permeability, resolving the contradiction between these two properties.

Inventive Principle:

Principle #35Parameter changes

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 configuration ensures good adhesiveness between the active material layer and the current collector while maintaining high permeability of the electrolyte solution, thereby achieving both excellent output characteristics and charge-discharge cycle characteristics.

Implementation Method 1

the styrene-butadiene rubber in a 10% region in a thickness direction, from a surface of the negative electrode active material layer, the surface being on an opposite side of the negative electrode current collector, is higher in glass transition temperature (Tg) than the styrene-butadiene rubber in a 10% region in a thickness direction, from a surface on a negative electrode current collector side

Methodology Applied

Scientific EffectGlass transition temperature:

Data Source

PatentUS12206088B2Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Publication Date: 2025.01.21 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A negative electrode for a nonaqueous electrolyte secondary battery, said negative electrode comprising a negative-electrode current collector, and a negative-electrode active material layer provided upon the negative-electrode current collector, wherein the negative-electrode active material layer includes a negative-electrode active material and a styrene-butadiene rubber, and the glass transition temperature (Tg) of the styrene-butadiene rubber in an area that extends 10% in the thickness direction from the surface of the reverse side of the negative-electrode active material layer from the negative-electrode current collector is higher than that of the styrene-butadiene rubber in an area that extends 10% in the thickness direction from the surface of the negative-electrode current collector side of the negative-electrode active material layer.