Partial Bonding Separator for Lithium Battery Internal Resistance
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Solution Overview
Problem
Conventional electrode assemblies in secondary batteries face issues with high internal resistance due to full bonding between electrodes and separators, which hinders gas discharge and electrolyte impregnation, leading to potential electrode separation and deformation during charging and discharging.
Innovation Solution
The electrode assembly employs a plasma discharging process to modify the separator surfaces, achieving partial bonding between the electrodes and separators, which reduces internal resistance by controlling the bonding area to 30% to 90% of the interface, thereby improving adhesion and electrolyte impregnation while allowing for efficient gas discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bonding interface between electrode and separator is entirely formed through lamination process, then adhesion between electrode and separator is improved, but internal resistance of battery cell increases and gas discharge becomes difficult
Solution Approach 1:
The patent applies partial bonding instead of complete bonding between electrode and separator. The bonding interface is formed only in specific regions rather than across the entire interface, achieving sufficient adhesion while preserving non-bonded areas that allow gas discharge and maintain low internal resistance. This partial action resolves the contradiction by providing just enough bonding to prevent separation without the harmful effects of complete bonding.
2Stability of the object's composition
If excessive adhesion is formed between electrode and separator, then separation between electrodes and separator is prevented, but electrolyte impregnation deteriorates and gas discharge becomes difficult
Solution Approach 1:
The patent implements local quality by creating different bonding characteristics in different regions of the electrode-separator interface. Some areas have bonding interfaces that provide strong adhesion to prevent separation, while other areas remain non-bonded to allow electrolyte impregnation and gas discharge. This spatial variation in bonding quality resolves the contradiction between stability and ease of manufacture.
3Strength
If full bonding interface is formed between electrode and separator, then structural integrity is improved, but the bonding interface acts as resistive layer increasing internal resistance
Solution Approach 1:
The patent segments the bonding interface into bonded regions and non-bonded regions. This segmentation allows the system to have both bonded areas that provide structural integrity and non-bonded areas that reduce internal resistance by not forming resistive layers. The segmented approach resolves the contradiction between strength and energy loss.
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 approach decreases internal resistance, maintains necessary adhesion, and enhances electrolyte impregnation, resulting in improved battery performance and structural integrity during charging and discharging cycles.
Implementation Method 1
one surface or both surfaces of the separator facing the electrodes are modified by a plasma discharging process
Implementation Method 2
bonded by heating and/or compression
Implementation Method 3
bonded by heating and/or compression
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present disclosure relates to an electrode assembly in which an internal resistance can be decreased while adhesion between a separator and an electrode is maintained and electrolyte impregnation can be improved, and provides a separator for lithium secondary battery of which a surface includes a processed area to which a corona discharging process is performed and a non-processed area to which the corona discharging process is performed and a method of manufacturing an electrode assembly including the same.