Battery Cell Exterior With Notched Pressure Relief for Swelling

Solution Overview

Problem

Lithium secondary batteries face a swelling phenomenon during repeated charging and discharging, leading to increased internal pressure, heat generation, and potential explosion or fire, necessitating improved internal pressure control and stability.

Innovation Solution

A battery cell design featuring an exterior material with a variable tensile strength, including a notch portion with lower tensile strength than the surrounding region, allows for controlled internal pressure adjustment by opening the notch portion when internal pressure exceeds a fracture point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the exterior material has high tensile strength throughout, then the battery cell can withstand high internal pressure, but the battery cell cannot release pressure when swelling occurs

Engineering Contradiction:

Improvetensile strength of exterior materialVSAvoidinternal pressure control

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The exterior material is designed with different tensile strengths in different regions: the first region has lower tensile strength to allow pressure release, while the second region has higher tensile strength to maintain structural integrity. This local differentiation resolves the contradiction by allowing the material to both withstand and release pressure as needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The exterior material is segmented into multiple regions with different mechanical properties. The first region (with lower tensile strength) acts as a pressure release zone, while the second region (with higher tensile strength) maintains overall structural strength, enabling both pressure control and structural stability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the exterior material has low tensile strength, then the battery cell can release internal pressure easily, but the battery cell cannot withstand high internal pressure

Engineering Contradiction:

Improveinternal pressure controlVSAvoidtensile strength of exterior material

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The exterior material is designed with different tensile strengths in different regions: the first region has lower tensile strength to allow pressure release, while the second region has higher tensile strength to maintain structural integrity. This local differentiation resolves the contradiction by allowing the material to both withstand and release pressure as needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The exterior material is segmented into multiple regions with different mechanical properties. The first region (with lower tensile strength) acts as a pressure release zone, while the second region (with higher tensile strength) maintains overall structural strength, enabling both pressure control and structural stability.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If the notch portion is manufactured separately and assembled, then the exterior material can have precise tensile strength control, but the manufacturing process becomes complex and less efficient

Engineering Contradiction:

Improvetensile strength controlVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The notch portion and the exterior material are manufactured as a single integrated component rather than separate parts. This merging maintains the tensile strength control achieved through the multi-region design while eliminating the complexity of separate manufacturing and assembly processes, improving overall manufacturing efficiency.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively controls internal pressure, enhancing the stability and safety of lithium secondary batteries by allowing pressure relief through the notch portion, thereby preventing explosions and fires.

Implementation Method 1

the tensile strength of the first region is provided to be lower than the tensile strength of the second region... allows for controlled internal pressure adjustment by opening the notch portion when internal pressure exceeds a fracture point

Methodology Applied

Scientific EffectFracture mechanics: Fracture Mechanics

Data Source

PatentUS20250087823A1Battery cell and manufacturing method of the same

Publication Date: 2025.03.13 SK ON CO LTD

AI summary

A battery cell of the present disclosure includes: an electrode assembly including a cathode, an anode, and a separator disposed between the cathode and the anode; and an exterior material accommodating the electrode assembly therein, wherein the exterior material includes: a first region including a notch portion provided on an outer surface; and a second region surrounding the first region, wherein the tensile strength of the first region is provided to be lower than the tensile strength of the second region.