Polydopamine-Coated Battery Separator for Wet Heat Stability

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Solution Overview

Problem

Secondary battery separators face challenges in maintaining dimensional stability at high temperatures, especially when wet with electrolyte, and in increasing the loading amount of polydopamine for improved performance.

Innovation Solution

A separator for secondary batteries is developed, comprising a porous substrate with a functional coating layer that includes a first coating layer containing inorganic particles, an acrylic binder, and polydopamine, and a second coating layer of polydopamine. This configuration enhances the loading amount of polydopamine and improves ionic conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a single coating layer is used, then the structure is simple, but the loading amount of polydopamine is insufficient

Engineering Contradiction:

Improveloading amount of polydopamineVSAvoidcoating layer structure

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The coating layer is divided into two distinct layers: a first coating layer containing inorganic particles, acrylic binder, and polydopamine, and a second coating layer containing polydopamine. This segmentation allows each layer to serve specific functions while collectively achieving high polydopamine loading

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first coating layer combines inorganic particles with acrylic binder and polydopamine to create a composite structure that provides both mechanical strength and high polydopamine content, while the second coating layer adds additional polydopamine functionality

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If excessive coating is applied to prevent separator shrinkage, then dimensional stability improves, but battery cell capacity decreases and resistance increases

Engineering Contradiction:

Improvedimensional stability of separatorVSAvoidbattery cell capacity

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The coating layers are applied locally on the separator surface with controlled thickness (first coating layer: 0.1-5 μm, second coating layer: 0.005-0.05 μm), providing dimensional stability only where needed on the separator surface rather than throughout the entire battery structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating layers are designed to be porous rather than dense, allowing electrolyte penetration and ion transport while still providing thermal shrinkage resistance, thus maintaining battery performance while achieving dimensional stability

Inventive Principle:

Principle #31Porous materials

3Reliability

If polydopamine loading is increased, then dimensional stability at high temperatures improves, but manufacturing complexity increases

Engineering Contradiction:

Improvedimensional stability at high temperatureVSAvoidcoating layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The polydopamine is distributed across two layers with different compositions and functions, allowing high total loading while maintaining manageable manufacturing complexity through standardized layering procedures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The thickness parameters of the two coating layers are optimized (first layer: 0.1-5 μm, second layer: 0.005-0.05 μm) to achieve the required dimensional stability while controlling the overall complexity of the coating structure

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

The enhanced polydopamine loading and ionic conductivity in the separator improve dimensional stability at high temperatures, preventing electrode exposure due to thermal shrinkage and ensuring safer and more efficient battery performance.

Implementation Method 1

it has been confirmed that when an acrylic binder and polydopamine are combined, a condensation reaction is proceeded, thereby remarkably increasing the loading amount of polydopamine

Methodology Applied

Scientific EffectCondensation reaction:

Implementation Method 2

the problem of electrode exposure due to thermal shrinkage of the separator under high temperature conditions can be solved

Methodology Applied

Scientific EffectThermal shrinkage resistance:

Implementation Method 3

a porous substrate; and a functional coating layer on at least one surface of the porous substrate

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentUS20250192363A1Separator for secondary battery, method for manufacturing same, and secondary battery

Publication Date: 2025.06.12 LG ENERGY SOLUTION LTD

AI summary

Disclosed is a separator for a secondary battery, which has excellent dimensional stability even at high temperatures when it is a wet state in which an electrolyte has been injected. The separator includes a porous substrate, and a functional coating layer disposed on at least one surface of the porous substrate. The functional coating layer includes a first coating layer and a second coating layer disposed on the first coating layer, the first coating layer contains inorganic particles, an acrylic binder, and polydopamine, and the second coating layer contains polydopamine.