Heat-Resistant Battery Separator Coating Without Inorganic Fillers

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Solution Overview

Problem

Existing electrochemical device separators face challenges with high processing inefficiency and inadequate heat resistance, particularly due to severe heat shrinking behavior at elevated temperatures, which can lead to short-circuits between electrodes.

Innovation Solution

A separator with a porous polymer substrate and a heat-resistant coating layer composed of a polyvinylidene fluoride (PVDF)-based polymer and polyvinyl pyrrolidone (PVP)-based polymer, where the PVP-based polymer has a molecular weight of 900,000 g/mol or more, and the coating layer has a thickness of 0.5 μm to 5.0 μm, providing enhanced heat resistance and stability without the need for dispersing or milling inorganic particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a porous coating layer is formed by coating a mixture of inorganic particles with a binder resin, then heat resistance is improved, but processing time increases due to dispersing and milling steps

Engineering Contradiction:

Improveheat resistanceVSAvoidprocessing time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The patent removes the inorganic particles from the coating layer formulation, extracting only the essential binder resin component. This eliminates the time-consuming dispersing and milling steps while maintaining heat resistance through the optimized polymer composition and coating process

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical dispersing and milling system with a chemical solution approach. By using a pre-formed polymer slurry with controlled viscosity and composition, the need for mechanical particle dispersion is eliminated, substituting a simpler coating and drying process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If a porous coating layer with inorganic particles is used, then heat resistance is improved, but device complexity increases due to multiple manufacturing steps

Engineering Contradiction:

Improveheat resistanceVSAvoidmanufacturing process complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the inorganic particle component from the coating formulation, thereby removing the associated manufacturing steps for particle dispersing, milling, and quality control. This simplifies the overall manufacturing process while maintaining the essential heat resistance function through optimized polymer selection

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The binder resin is formulated to perform multiple functions simultaneously: providing heat resistance, ensuring adequate adhesion to the porous substrate, and maintaining coating integrity. This multi-functionality eliminates the need for separate inorganic particle additives that would otherwise be required for heat resistance

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a separator with enhanced heat resistance is designed, then safety is improved, but thickness increases reducing processing efficiency

Engineering Contradiction:

ImprovesafetyVSAvoidprocessing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters of the binder resin, specifically using polymers with high glass transition temperatures and optimized molecular weights. This allows achieving enhanced heat resistance at thinner coating thicknesses, thereby maintaining processing efficiency while improving safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating system using multiple polymer components with complementary properties. The combination of polymers with different Tg values and molecular weights provides synergistic effects, achieving superior heat resistance in a thin coating layer that does not compromise processing efficiency

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

The solution significantly improves processing efficiency and achieves excellent heat resistance and stability, preventing short-circuits while maintaining a small thickness, thus ensuring safer electrochemical devices.

Implementation Method 1

the PVP-based polymer has a molecular weight (Mw) of 900,000 g/mol or more... the separator has an air permeability of 900 s/100 cc or less... preventing short-circuits while maintaining a small thickness, thus ensuring safer electrochemical devices

Methodology Applied

Scientific EffectThermal stabilization:

Implementation Method 2

it is possible to maintain electrical insulation between a positive electrode and a negative electrode, even when an electrochemical device is overheated, thereby preventing a short-circuit

Methodology Applied

Scientific EffectThermal resistance:

Data Source

PatentUS12100860B2Separator for electrochemical device and an electrochemical device comprising the same

Publication Date: 2024.09.24 LG ENERGY SOLUTION LTD

AI summary

A separator for an electrochemical device and an electrochemical device comprising the same. The separator comprises a porous polymer substrate and a heat resistant coating layer on at least one surface of the porous polymer substrate. The heat resistant coating layer is a porous polymer layer having pores, and comprises a polyvinyl pyrrolidone-based polymer and a polyvinylidene fluoride (PVDF)-based polymer.