Lithium Battery Insulation Case Composite Rigidity

Solution Overview

Problem

Lithium secondary batteries face the risk of short-circuiting due to the weak rigidity of polypropylene insulation cases, which deform under external forces, causing local stress on the electrode assembly.

Innovation Solution

The use of a resin or resin composite material with a tensile strength of at least 500 kg/cm2 and compressive strength of at least 900 kg/cm2 for the insulation case, which prevents deformation and uniformly distributes stress, thereby enhancing the battery's resistance to physical forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polypropylene insulation case is used, then insulation function is provided, but rigidity is weak causing deformation under external forces

Engineering Contradiction:

ImproverigidityVSAvoidshort-circuit prevention

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies composite materials by combining polypropylene with glass fiber or carbon fiber to create a reinforcement case. This composite structure provides both the necessary rigidity to resist external forces and maintain battery shape, and the insulation properties to prevent short-circuiting. The reinforcement fibers embedded in the polypropylene matrix create a material that is both strong and electrically insulating.

Inventive Principle:

Principle #40Composite materials

2Strength

If insulation case thickness is increased to improve rigidity, then strength increases, but battery thickness increases

Engineering Contradiction:

ImproverigidityVSAvoidbattery thickness

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

The patent applies local quality by strategically placing reinforcement fibers (glass fiber or carbon fiber) within the polypropylene insulation case. Instead of uniformly increasing the entire case thickness, the reinforcement is localized in areas where structural strength is most needed, such as around the electrode assembly and at stress concentration points. This provides enhanced rigidity where required while maintaining overall battery compactness.

Inventive Principle:

Principle #3Local quality

3Reliability

If polypropylene insulation case is used, then insulation function is provided, but deformation causes local stress on electrode assembly

Engineering Contradiction:

Improveinsulation functionVSAvoidstress distribution uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by combining polypropylene with glass fiber or carbon fiber to create a reinforcement case. This composite structure provides both the necessary rigidity to resist external forces and maintain battery shape, and the insulation properties to prevent short-circuiting. The reinforcement fibers embedded in the polypropylene matrix create a material that is both strong and electrically insulating.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS7666546B2Lithium secondary battery

Publication Date: 2010.02.23 SAMSUNG SDI CO LTD

AI summary

A lithium secondary battery includes an electrode assembly having first and second electrodes wound together with a separator interposed between them and an insulation case positioned on the electrode assembly. The insulation case is made of a resin or resin composite material having a tensile strength of at least 500 kg/cm2.