Electrode Assembly With Porous Adhesive Layers
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Solution Overview
Problem
Existing electrode assemblies for secondary batteries face challenges such as high electrical resistance and safety issues due to internal short circuits, particularly when exposed to high temperatures, which can lead to fires or explosions.
Innovation Solution
The electrode assembly features a zigzag or sequential winding pattern using a first separator with a porous polyolefin substrate and a porous electrode adhesive layer on one surface, and a second separator with adhesive layers on both surfaces, comprising inorganic particles and a binder polymer, which reduces electrical resistance and prevents inorganic particle escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If organic-inorganic composite layers are introduced into separators to improve heat resistance, then heat resistance is improved, but electrical resistance increases
Solution Approach 1:
The patent applies local quality by forming the organic-inorganic composite adhesive layer only on one surface of the separator (the surface contacting electrodes) rather than both surfaces. This localized application provides heat resistance where needed (at the electrode interface) while minimizing the amount of inorganic particles that would increase electrical resistance, thus resolving the contradiction between heat resistance and electrical resistance
Solution Approach 2:
The patent uses partial action by applying the composite adhesive layer to only one surface of the separator instead of both surfaces. This partial application is sufficient to achieve the desired heat resistance at the critical electrode interface while reducing the overall quantity of inorganic particles in the separator structure, thereby maintaining lower electrical resistance
2Temperature
If separators are exposed to high temperatures, then heat resistance is tested, but shrinkage or breakage occurs causing internal short circuits
Solution Approach 1:
The patent uses composite materials by combining organic polymer matrix with inorganic particles to create an organic-inorganic composite adhesive layer. This composite structure provides superior heat resistance compared to pure organic separators, preventing shrinkage and breakage at high temperatures while maintaining structural integrity to prevent internal short circuits
Solution Approach 2:
The patent applies preliminary action by pre-coating the separator with the organic-inorganic composite adhesive layer before battery assembly. This pre-applied layer provides immediate thermal protection and structural reinforcement that prevents high-temperature shrinkage and breakage, thereby preventing internal short circuits before they can occur during battery operation or abuse conditions
3Strength
If adhesive layers are formed on both surfaces of separators, then electrode adhesion is improved, but inorganic particles may escape and electrical resistance increases
Solution Approach 1:
The patent applies local quality by forming the adhesive layer only on one surface of the separator (the surface that contacts the electrodes) rather than both surfaces. This localized adhesion is sufficient to maintain electrode attachment while minimizing the total quantity of inorganic particles in the separator structure, thereby reducing the risk of particle escape and maintaining lower electrical resistance
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 enhances the performance and safety of secondary batteries by minimizing electrical resistance and preventing inorganic particle exposure, leading to improved stability and output.
Implementation Method 1
a first porous electrode adhesive layer on one surface of the porous polyolefin substrate, to which electrodes of the unit cells are adhered
Implementation Method 2
a porous polyolefin substrate
Implementation Method 3
porous separator
Data Source
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AI summary
An electrode assembly is disclosed. The electrode assembly has a structure in which a plurality of unit cells are bonded to one or both surfaces of a first separator whose length is greater than width and are stacked in a zigzag pattern or wound sequentially. The first separator includes a first porous electrode adhesive layer, to which electrodes of the unit cells are adhered, formed at one surface thereof to which the unit cells are bonded. The first porous electrode adhesive layer includes a mixture of inorganic particles and a binder polymer. Each of the unit cells includes a second separator. The second separator includes second porous electrode adhesive layers, to which electrodes of the unit cell are adhered, formed at both surfaces thereof. Each of the second porous electrode adhesive layers includes a mixture of inorganic particles and a binder polymer. Further disclosed is an electrochemical device including the electrode assembly. The separators, each of which includes the porous electrode adhesive layers, to which electrodes are adhered, formed at both surfaces thereof, and the separator including a porous electrode adhesive layer, to which electrodes are adhered, formed at one surface thereof are separately used in the electrode assembly. This reduces the electrical resistance of the separators, contributing to an improvement in the performance of the electrochemical device.