High-Elongation Insulating Layer for Battery Case Safety
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to thermal instability and rapid exothermic reactions during overcharging and physical penetration, leading to potential ignition or explosion, which existing additives fail to adequately address.
Innovation Solution
A case for secondary batteries featuring a laminate sheet with an insulating layer having an elongation percentage of 10% or more, composed of polyurethane or aramid fibers and a plasticizer, which prevents direct contact between conductive objects and electrodes, thereby enhancing safety against physical forces and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional case structure without high-elongation insulating layer is used, then the battery structure is simple and manufacturing is easy, but the battery safety is poor due to inability to prevent short circuits during nail penetration or impact
Solution Approach 1:
The case is constructed as a laminate sheet comprising multiple layers including an outer layer, an intermediate layer, and an inner layer, where at least one layer is an insulating layer with elongation percentage of 10% or more. This composite structure combines materials with different properties to achieve both safety and structural requirements.
Solution Approach 2:
The insulating layer is designed with high elongation capability (10% or more) allowing it to deform and wrap around penetrating objects such as nails during impact or penetration events. This flexibility enables the layer to maintain continuity and prevent short circuits between electrodes even under mechanical stress.
2Reliability
If no insulating layer with high elongation is added, then the manufacturing process is simple, but the battery cannot prevent short circuits during physical penetration or impact
Solution Approach 1:
The laminate sheet integrates an insulating layer with specific elongation properties (10% or more) into the case structure. This layer is positioned between the outer and inner layers, creating a composite structure that provides short circuit prevention during manufacturing and operation.
Solution Approach 2:
The insulating layer's high elongation characteristic allows it to act as a flexible barrier that can deform during penetration events while maintaining its insulating function, preventing direct contact between conductive objects and electrodes.
3Reliability
If the insulating layer has low elongation percentage, then the case structure is simpler and manufacturing is easier, but the layer cannot wrap conductive objects during penetration to prevent short circuits
Solution Approach 1:
The insulating layer is specifically designed with elongation percentage of 10% or more, enabling it to stretch and wrap around penetrating objects during impact or nail penetration events. This high elongation capability allows the layer to maintain its barrier function even when deformed.
Solution Approach 2:
The key parameter of elongation percentage is set to 10% or more for the insulating layer, distinguishing it from conventional materials. This parameter change enables the layer to exhibit wrapping behavior during penetration events, effectively preventing short circuits.
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 high elongation percentage insulating layer effectively prevents short circuits and heat generation, thereby enhancing battery stability and safety by elongating to wrap conductive objects and preventing direct contact, thus inhibiting ignition and thermal runaway.
Implementation Method 1
an insulating layer having an elongation percentage of 10% or more... the insulating layer is effectively elongated in a shape wherein an object having conductivity as an electrode is wrapped, thereby being penetrated
Implementation Method 2
When heat is generated in a battery, a separator is contracted, additional short circuit in a positive electrode and a negative electrode is induced... the insulating layer prevents direct contact between an object having conductivity and electrodes or direct contact between a positive electrode and a negative electrode, thereby effectively addressing the above problem
Data Source
Figure 1~3
Figure 4
AI summary
Disclosed is a case for secondary batteries including a laminate sheet composed of multiple layers, the laminate sheet including an insulating layer having an elongation percentage of 10% or more.