Low Bis-Cyanoethyl Ether Polymer Binder for Battery Separator Heat Resistance

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Solution Overview

Problem

Current lithium ion secondary battery separators with 2-cyanoethyl group-containing polymers as binders in heat-resistant layers face challenges in achieving sufficient heat resistance and ion conductivity due to high bis-cyanoethyl ether content, leading to reduced mechanical strength and ion conductivity, which can result in battery deterioration and safety issues during internal short circuits.

Innovation Solution

A 2-cyanoethyl group-containing polymer binder with a bis-cyanoethyl ether content of 0.5% by weight or less is used, ensuring strong adhesion with inorganic filler particles and maintaining mechanical strength and ion conductivity, while minimizing bis-cyanoethyl ether's negative effects on heat resistance and ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a 2-cyanoethyl group-containing polymer is used as a binder in a heat-resistant porous layer, then adhesion with inorganic filler particles is improved, but bis-cyanoethyl ether content increases which reduces mechanical strength and ion conductivity

Engineering Contradiction:

Improveadhesion strengthVSAvoidmechanical strength and ion conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies parameter changes by strictly controlling the bis-cyanoethyl ether content to 0.5% by weight or less through optimized polymerization conditions (temperature, time, catalyst selection), thereby maintaining both adhesion strength and mechanical properties simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by ensuring uniform distribution of the 2-cyanoethyl group-containing polymer within the heat-resistant porous layer, creating localized strong adhesion zones while maintaining overall structural integrity and ion conductivity

Inventive Principle:

Principle #3Local quality

2Reliability

If the separator uses a conventional porous substrate, then ion conductivity is maintained, but heat resistance at high temperatures (600°C or higher) is insufficient

Engineering Contradiction:

Improveheat resistanceVSAvoidheat shrinkage and melting

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by combining a porous substrate with a heat-resistant porous layer containing inorganic filler particles and 2-cyanoethyl group-containing polymer, creating a composite structure that provides both ion conductivity and high-temperature heat resistance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies preliminary action by pre-forming the heat-resistant porous layer on the porous substrate before battery operation, establishing protective functionality against heat shrinkage and melting at 600°C or higher temperatures

Inventive Principle:

Principle #10Preliminary action

3Reliability

If internal short circuit occurs, then Joule heat is generated causing temperature increase, but the separator shrinks or melts leading to battery safety hazards

Engineering Contradiction:

Improvebattery safetyVSAvoidtemperature resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies beforehand cushioning by incorporating a heat-resistant porous layer with specific binder composition that acts as a thermal buffer, preventing heat-induced shrinkage and melting even when temperature reaches 600°C or higher during internal short circuit

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

The solution provides a non-aqueous electrolyte battery separator with enhanced heat resistance and mechanical strength, maintaining ion conductivity and load characteristics, thereby improving battery performance and safety by preventing heat-induced failures.

Implementation Method 1

ensuring strong adhesion with inorganic filler particles

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

the separator comprising the porous substrate melts to block the pores

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

When the temperature increases owing to the heat generated by short circuit, the separator comprising the porous substrate melts

Methodology Applied

Scientific EffectHeat-induced phase change: Phase Change

Implementation Method 4

improved heat resistance at the time of internal short circuit

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Implementation Method 5

a non-aqueous electrolyte battery with improved heat resistance

Methodology Applied

Scientific EffectHeat resistance: Thermal Insulation

Implementation Method 6

heat is generated in the battery due to Joule heat caused by short circuit

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2509138B1Use of a binder comprising 2-cyanoethyl group-containing polymer for a separator of non-aqueous electrolyte battery , and process for preparing the separator

Publication Date: 2019.11.20 MATSUGAKI CHEM IND

AI summary

An object of the invention is to provide a binder for a separator, which can be comprised by a non-aqueous electrolyte battery with improved battery properties and heat resistance; a separator comprising the binder; and a non-aqueous electrolyte battery comprising the separator. More specifically, provided is a binder for a separator of a non-aqueous electrolyte battery, the separator comprising a 2-cyanoethyl group-containing polymer having bis-cyanoethyl ether content of 0.5% by weight or less as an impurity.