Lithium Battery Electrode Assembly with Segmented Separator Adhesion
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Solution Overview
Problem
Rechargeable lithium batteries with high energy density face challenges in maintaining appropriate air permeability of the separator while ensuring adherence between the electrode and separator, leading to performance degradation.
Innovation Solution
An electrode assembly is designed with a current collector, electrode active material layer, and adhesive layer, where the separator has a larger surface area than the adhesive layer, and its surface is divided into an adhesive region and an overhang region, ensuring suitable adherence and air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator area is increased to maintain air permeability, then air permeability is improved, but adherence between electrode and separator deteriorates
Solution Approach 1:
The separator is divided into two distinct regions: an adhesive region that contacts the electrode active material layer to ensure strong adherence, and an overhang region that extends beyond the electrode to maintain air permeability. This segmentation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the separator are given different functional properties: the adhesive region is optimized for bonding with the electrode (with adhesive layer contact), while the overhang region is optimized for air flow (without adhesive layer contact). This local differentiation resolves the contradiction between adherence and air permeability.
2Reliability
If adhesive layer coverage is increased to improve adherence, then adherence between electrode and separator is improved, but air permeability of separator deteriorates
Solution Approach 1:
The adhesive layer coverage is segmented rather than continuous. It is applied only in the adhesive region where electrode contact is needed, while the overhang region remains free of adhesive layer to preserve air permeability pathways.
Solution Approach 2:
Instead of applying adhesive layer across the entire separator surface (excessive action), the adhesive layer is applied partially only where needed for adherence. This partial action maintains the necessary bond strength while preserving air permeability in the uncovered overhang region.
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 configuration maintains excellent adherence between electrodes and separators while maintaining appropriate air permeability, thereby minimizing battery performance degradation and ensuring safety and reliability.
Implementation Method 1
an adhesive layer on the electrode active material layer
Implementation Method 2
maintaining air permeability of the separator within an appropriate or suitable range
Data Source
AI summary
An electrode assembly and a rechargeable lithium battery including the same are disclosed herein. The electrode assembly includes an electrode and a separator, wherein the electrode includes a current collector, an electrode active material layer on the current collector, and an adhesive layer on the electrode active material layer; and wherein the separator has a larger surface area than the adhesive layer of the electrode; and a surface of the separator opposing the adhesive layer of the electrode is divided into an adhesive region in contact with the adhesive layer of the electrode and an overhang region not in contact with the adhesive layer of the electrode.