Lithium Ion Battery Separator With Localized Coating Thickness

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Solution Overview

Problem

Current lithium ion battery separators with uniform ceramic and organic coatings lack thickness variation, leading to inadequate safety in critical areas, such as corners, where heat shrinkage can cause short circuits and thermal runaway.

Innovation Solution

A separator with a porous substrate and a coating layer comprising inorganic particles and a binder, featuring varying thickness in specific regions, particularly at corners, to enhance local strength and safety without increasing the battery's overall thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a uniform coating layer is applied on the entire surface of the polyolefin separator, then the manufacturing process is simple and consistent, but the local safety in critical areas such as corners is insufficient

Engineering Contradiction:

Improvecoating process simplicityVSAvoidlocal safety in critical areas

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies different coating thicknesses to different regions of the separator. Critical areas such as corners receive a first coating layer with greater thickness, while non-critical areas receive a second coating layer with smaller thickness. This local differentiation ensures enhanced safety where needed while maintaining manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The separator surface is divided into multiple regions with different coating requirements. The coating layer is segmented into a first coating layer for critical areas and a second coating layer for non-critical areas, allowing tailored protection strategies for different zones of the separator.

Inventive Principle:

Principle #1Segmentation

2Strength

If the coating layer thickness is increased uniformly across the entire separator, then the local strength and safety are improved, but the overall battery thickness and volume increase

Engineering Contradiction:

Improveseparator strengthVSAvoidbattery volume

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

Instead of uniformly increasing coating thickness across the entire separator, the patent selectively applies thicker coating only to critical areas such as corners where heat shrinkage and short circuit risks are highest. This localized approach enhances separator strength where needed while minimizing the overall volume increase of the battery.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies excessive coating thickness (first thickness) only to specific critical regions rather than uniformly across the entire separator. This partial application of excessive material provides enhanced protection at danger zones while avoiding unnecessary material usage and volume increase in non-critical areas.

Inventive Principle:

Principle #16Partial or excessive action

3Strength

If the coating layer thickness is increased uniformly across the entire separator, then the local strength and safety are improved, but the energy density of the battery is reduced

Engineering Contradiction:

Improveseparator strengthVSAvoidenergy density

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent selectively increases coating thickness only in critical areas such as corners where safety is most needed, rather than uniformly across the entire separator. This localized thickening provides enhanced strength and safety while minimizing the overall material usage, thereby preserving the battery's energy density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies excessive coating thickness (first thickness greater than second thickness) only to specific critical regions. This partial application of enhanced protection ensures adequate strength where heat shrinkage risks exist while avoiding unnecessary material consumption that would reduce the battery's energy density.

Inventive Principle:

Principle #16Partial or excessive action

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 varying thickness of the coating layer improves the local strength of the separator, enhancing safety and performance by providing enhanced protection at critical areas without increasing the battery's volume or reducing energy density.

Implementation Method 1

a first coating layer disposed on at least one surface of the porous substrate; the first coating layer comprises an inorganic particle and a binder

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS11575178B2Separator and lithium ion battery

Publication Date: 2023.02.07 NINGDE AMPEREX TECHNOLOGY LTD

AI summary

An aspect of the present application provides a separator comprising a porous substrate, and a first coating layer disposed on at least one surface of the porous substrate and comprising an inorganic particle and a binder. The first coating layer comprises a first region and a second region, the first coating layer in the first region comprises a first thickness, and the first coating layer in the second region comprises a second thickness; the first thickness is greater than the second thickness, and the area in the second region is greater than the area in the first region. Another aspect of the present application provides a lithium ion battery comprising a positive electrode, a negative electrode and the above separator. The purpose of the present application is to provide a separator having an increased thickness in a partial coating layer and a lithium ion battery comprising the above separator.