Secondary Battery Outermost Layer Electrode Warpage Stress
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Solution Overview
Problem
The existing secondary battery design with an electrode material layer on one main surface of the current collector in the outermost layer experiences warpage stress, leading to inadequate adhesion to the separator and compromised battery performance.
Innovation Solution
A secondary battery with a planar stacking structure where the outermost layer electrode, having an electrode material layer on one main surface, is wound around a partial electrode assembly to apply tension and maintain its shape, thereby suppressing warpage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode material layer is provided only on one main surface of the current collector in the outermost layer electrode, then the energy density is improved, but warpage stress occurs leading to inadequate adhesion to the separator
Solution Approach 1:
The patent applies preliminary anti-action by providing a protective coating layer on the current collector of the outermost layer electrode before assembly. This coating layer prevents warpage stress from developing during battery operation, thereby maintaining adhesion between the electrode material layer and separator while enabling the single-sided electrode structure for higher energy density.
Solution Approach 2:
The patent uses composite materials by combining the current collector, electrode material layer, and protective coating layer into a multi-layer structure. The coating layer acts as a composite component that compensates for the warpage tendency of the single-sided electrode structure, ensuring reliable adhesion while maintaining the energy density benefits of the outermost layer design.
2Volume of moving object
If the electrode material layer is provided only on one main surface of the current collector in the outermost layer electrode, then the battery size is reduced, but warpage stress occurs compromising battery performance
Solution Approach 1:
The protective coating layer is applied in advance to prevent warpage stress from compromising battery performance. This preliminary protective measure enables the battery to maintain compact size through single-sided electrode design while ensuring reliable performance by preventing adhesion failure during operation.
3Quantity of substance
If pressure treatment is performed to obtain desired density of the electrode, then the energy density is improved, but warpage stress occurs due to differential stretching between current collector and electrode material layer
Solution Approach 1:
The multi-layer composite structure including the protective coating layer distributes the stress during pressure treatment more uniformly. The coating layer acts as a stress buffer that reduces differential stretching between the current collector and electrode material layer, enabling high energy density through effective pressure treatment while minimizing warpage stress.
Solution Approach 2:
The patent modifies the physical parameters of the current collector by adding a coating layer with different mechanical properties. This parameter change in the current collector structure allows it to better match the thermal and mechanical expansion characteristics of the electrode material layer during pressure treatment, reducing warpage stress while maintaining high energy density.
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 effectively prevents warpage stress in the outermost layer electrode, ensuring proper adhesion and function within the electrode assembly, allowing the battery to exhibit desired characteristics without reducing energy density.
Implementation Method 1
the outermost layer electrode, having an electrode material layer on one main surface, is wound around a partial electrode assembly to apply tension and maintain its shape, thereby suppressing warpage stress
Implementation Method 2
heat-pressing (also referred to as 'hot-pressing') the laminate to connect layers to each other
Data Source
AI summary
A secondary battery that includes a partial electrode assembly having a planar stacking structure in which a plurality of electrode constituting layers are stacked, the plurality of electrode constituting layers each include a pair of electrodes and a separator therebetween, and at least one of the pair of electrodes includes a double-sided electrode having an electrode material layer on opposed main surfaces of a current collector; and an outermost layer electrode surrounding the partial electrode assembly along at least a portion of a contour of the partial electrode assembly in a cross-sectional view thereof, the outermost layer electrode including a single-sided electrode having an outermost electrode material layer on one main surface of an outermost current collector.