Jelly-Roll Electrode Composite Membrane Deformation Prevention
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Solution Overview
Problem
Jelly-roll type electrode assemblies face issues with deformation and safety due to stress accumulation during charge/discharge, and conventional organic/inorganic composite membranes can cause 'tail out' conditions and damage during mandrel removal, leading to reduced battery performance and safety.
Innovation Solution
A composite membrane with organic/inorganic composite layers applied to both sides, featuring microfine pores and a low interfacial friction coefficient with the mandrel, is used to moderate volume variations and prevent deformation, improving safety and production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an organic/inorganic composite membrane is used to prevent deformation, then the mechanical strength and deformation resistance are improved, but the interfacial friction with the mandrel increases causing tail out conditions
Solution Approach 1:
The patent applies a dual-layer structure where the outer layer has high mechanical strength to prevent deformation, while the inner layer has low friction coefficient to prevent tail out during mandrel removal. This local differentiation of material properties resolves the contradiction between strength and friction.
Solution Approach 2:
The patent uses a composite membrane structure combining organic and inorganic materials with different functional properties. The outer layer provides mechanical strength through inorganic particles, while the inner layer provides low friction through specific material selection, thus resolving the contradiction between strength and friction.
2Ease of operation
If the interfacial friction coefficient is reduced to prevent tail out, then the ease of mandrel removal is improved, but the ability to moderate volume variation during charge/discharge is reduced
Solution Approach 1:
The patent creates different functional zones within the membrane: the inner layer is optimized for low friction to facilitate mandrel removal, while the outer layer is optimized for volume moderation during battery operation. This spatial differentiation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The membrane is segmented into multiple layers with distinct functions. The inner layer handles the friction issue during manufacturing, while the outer layer handles the volume variation issue during battery operation, thus resolving the contradiction through functional segmentation.
3Reliability
If a conventional organic/inorganic composite membrane is used, then the thermal safety is improved, but the production workability decreases due to high friction during winding
Solution Approach 1:
The patent employs a composite membrane structure where the outer layer maintains thermal safety through inorganic particles, while the inner layer is specifically designed with low friction properties to improve production workability during the winding process. This composite approach resolves the contradiction between thermal safety and manufacturability.
Solution Approach 2:
The membrane structure differentiates material properties across its thickness: the outer surface maintains thermal safety characteristics, while the inner surface near the mandrel interface provides low friction for easy removal, thus resolving the contradiction between thermal safety and production ease.
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 reduces the 'tail out' condition, enhances mechanical strength, and inhibits deformation, thereby improving battery safety and performance by buffering electrode expansion and contraction.
Implementation Method 1
an organic/inorganic composite layer which includes microfine pores capable of buffering contraction and/or expansion of an electrode
Implementation Method 2
the interfacial friction coefficient (μ) between the composite membrane and the mandrel is 0.28 or less
Data Source
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AI summary
Provided is a method for fabrication of a jelly-roll type electrode assembly having a cathode/separation membrane/anode laminate structure, including: (a) coating both sides of a porous substrate with organic/inorganic composite layers, each of which includes inorganic particles and an organic polymer as a binder, so as to fabricate a composite membrane; and (b) inserting one end of a sheet laminate comprising a cathode sheet and an anode sheet as well as the composite membrane into a mandrel, winding the sheet laminate around the mandrel, and then, removing the mandrel, wherein the organic/inorganic composite layer includes microfine pores capable of moderating a variation in volume during charge/discharge of a secondary battery and an interfacial friction coefficient between the composite membrane and the mandrel is not more than 0.28.