Thermal Contractible Protection Layer for Secondary Battery Swelling
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Solution Overview
Problem
Secondary batteries experience swelling during charging and discharging, which reduces their lifespan due to changes in the electrode-separator interface, leading to increased resistance and potential deformation.
Innovation Solution
A thermal contractible protection layer made of insulative materials like nylon or polypropylene is applied around the electrode assembly to suppress swelling by contracting with heat and providing physical strength, preventing deformation and improving lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electrode assembly is charged and discharged, then the battery provides energy storage and release function, but the electrode expands causing swelling and reducing lifespan
Solution Approach 1:
A thermal contractible protection layer is disposed on the outer surface of the electrode assembly before swelling occurs. This protection layer is configured to contract when heated, providing pre-positioned constraint that prevents the electrode assembly from swelling during charging and discharging cycles, thereby cushioning against the harmful expansion before it causes damage.
Solution Approach 2:
The protection layer utilizes thermal parameter changes - specifically, it is designed to contract when exposed to heat. This thermal response changes the physical state of the protection layer from a relaxed state to a contracted state, allowing it to dynamically adjust and constrain the electrode assembly during thermal events that occur during battery operation.
2Reliability
If the electrode assembly swells, then the interface between electrode and separator changes, but this increases resistance and reduces battery performance
Solution Approach 1:
The thermal contractible protection layer is installed on the electrode assembly surface in advance, creating a constraint mechanism that prevents swelling before it can disrupt the electrode-separator interface. This beforehand cushioning maintains stable interfaces and prevents the harmful increase in resistance that would result from interface degradation.
3Reliability
If a protection layer is added to suppress swelling, then the lifespan is improved, but the device complexity increases
Solution Approach 1:
The protection layer is implemented as a thin, flexible layer with thermal contractible properties. This thin-film approach provides the necessary swelling constraint without adding significant structural complexity, weight, or volume to the battery assembly, maintaining simplicity while achieving the lifespan extension goal.
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 thermal contractible protection layer effectively reduces electrode assembly swelling, enhances lifespan, and prevents short circuits, allowing for continuous use as it returns to its original state upon cooling, while also improving manufacturing ease and usability.
Implementation Method 1
a thermal contractible protection layer disposed on an outer surface of the electrode assembly and contracted by heat
Data Source
AI summary
The present invention relates to a secondary battery comprising: an electrode assembly; and a thermal contractible protection layer disposed on an outer surface of the electrode assembly and contracted by heat.