Striped Separator Adhesive Layer for Lithium Plating Control
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Solution Overview
Problem
Lithium-ion batteries face challenges with high risks of lithium precipitation and formation of dead lithium areas at the negative electrode, which compromise safety and reliability.
Innovation Solution
The secondary battery design includes a striped adhesive layer on the separator, with specific peel strengths between the separator and negative electrode material layer, and between the negative electrode material layer and current collector, optimizing ion and electron transport channels to reduce lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the separator directly contacts the negative electrode material layer, then the structure is simple, but lithium precipitation occurs at the negative electrode
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the separator and the negative electrode material layer. This adhesive layer serves as a mediator that prevents direct contact between the separator and the electrode material, thereby eliminating the conditions that lead to lithium precipitation while maintaining structural simplicity.
Solution Approach 2:
The adhesive layer is extracted as a separate functional component from the separator structure. By taking out the adhesion function and implementing it through a distinct layer, the patent prevents the separator from directly contacting the electrode material, thus solving the lithium precipitation problem while keeping the overall design straightforward.
2Strength
If the adhesive layer is made thicker to improve adhesion, then bonding strength increases, but ion transport channels are blocked
Solution Approach 1:
The thickness of the adhesive layer is precisely controlled within a specific range (1-5 μm). By changing this critical parameter to an optimal value, the patent achieves sufficient bonding strength while maintaining adequate ion transport channels, thus resolving the contradiction between adhesion and ion conductivity.
Solution Approach 2:
The adhesive layer is designed with non-uniform distribution through the striped pattern, where adhesive material is concentrated in specific regions rather than uniformly distributed. This local quality approach ensures strong bonding where needed while preserving ion transport pathways in other areas.
3Reliability
If the adhesive layer is made thinner to improve ion transport, then ion transport channels are enhanced, but adhesion strength decreases
Solution Approach 1:
The patent optimizes the adhesive layer thickness to a specific range (1-5 μm) that balances ion transport and adhesion requirements. This precise parameter control ensures that the layer is thin enough for ion transport but thick enough to provide sufficient bonding strength.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing adhesive resin, conductive carbon black, and binder. This composite structure provides both adequate adhesion strength and sufficient electrical conductivity for ion transport, resolving the contradiction between bonding and ion conductivity.
4Volume of moving object
If the separator extension part is reduced to minimize dead lithium areas, then the structure is compact, but lithium precipitation risk increases
Solution Approach 1:
The adhesive layer acts as an intermediary that extends onto the separator extension part, creating a protective barrier that prevents lithium precipitation even when the extension part is minimized. This mediator allows the separator extension to be reduced while maintaining safety.
Solution Approach 2:
The adhesive layer is pre-applied onto the separator extension part during manufacturing, creating a protective configuration before battery operation. This preliminary action ensures that when the separator extension is minimized, the adhesive layer is already in position to prevent lithium precipitation.
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
This design enhances safety by reducing lithium precipitation and dead lithium area formation, improving the battery's safety and reliability.
Implementation Method 1
a first adhesive layer, the first adhesive layer being disposed on the third surface and being of a striped structure
Implementation Method 2
an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator
Data Source
AI summary
A secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator includes a substrate layer and a first adhesive layer. The substrate layer includes a third surface and a fourth surface opposite to each other. The third surface faces the negative electrode plate. The first adhesive layer is disposed on the third surface and is of a striped structure. A part of the separator extending beyond the negative electrode plate is defined as a separator extension part. The first adhesive layer is at least partially located on the separator extension part. A peel strength between the separator and the first negative electrode material layer is a N/m, and a peel strength between the first negative electrode material layer and the negative electrode current collector is b N/m, where 6.0≤a≤15.0, and a<b.