Wound Secondary Battery Electrode Structure for Deformation Suppression
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Solution Overview
Problem
Conventional secondary batteries experience electrode plate deformation due to local stress during charging and discharging, leading to potential self-discharge through internal short circuits.
Innovation Solution
A secondary battery design with a negative electrode having a non-facing portion that does not face the positive electrode, featuring a low friction region with a static friction coefficient of less than or equal to 0.4, and utilizing insulating members on the non-facing portion to alleviate stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode assembly is wound tightly to increase capacity, then the battery capacity increases, but local stress concentrates at the winding core portion causing electrode plate deformation
Solution Approach 1:
The patent applies local quality by creating a non-facing portion at the winding start side end of the negative electrode, where the electrode does not face the positive electrode with the separator interposed therebetween. This local structural modification redistributes the stress that would otherwise concentrate at the winding core portion, preventing electrode plate deformation while maintaining the wound configuration for high capacity.
2Stability of the object's composition
If an insulating tape is attached to the negative electrode current collector to suppress deformation, then electrode plate deformation is suppressed, but the device complexity increases
Solution Approach 1:
The patent extracts the insulating tape from being a separate additional component and integrates it as part of the negative electrode structure itself. The insulating tape is attached to the negative electrode current collector at the winding start side end, forming an integrated assembly that suppresses deformation without requiring separate deformation prevention mechanisms.
3Strength
If the friction coefficient between the electrode and separator is high, then the electrode is firmly held, but stress concentration increases leading to deformation
Solution Approach 1:
The patent applies parameter changes by modifying the friction coefficient parameter at the winding start side end. The insulating tape creates a low-friction region with a friction coefficient of 0.05 or less between the negative electrode and separator, which reduces stress concentration and prevents electrode plate deformation while the insulating properties maintain adequate holding strength.
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
Suppresses electrode plate deformation during charging and discharging, preventing internal short circuits and enhancing battery stability.
Implementation Method 1
a surface on the non-facing portion has a low friction region where a friction coefficient with the facing separator is 0.05 or less
Data Source
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AI summary
The present invention provides a secondary battery with which electrode plate deformation caused by charging and discharging can be suppressed. This secondary battery has an electrode body in which a positive electrode (11) and a negative electrode (12) that has a negative electrode mixture layer (50) disposed on a negative electrode core body (48) are wound with a separator interposed therebetween. The secondary battery is characterized in that the negative electrode (12) has, at a winding start-side end, an outer peripheral-side non-facing section (44) and an inner peripheral-side non-facing section (46) that do not face the positive electrode (11), with the separator interposed therebetween, and at least one of the surface on the outer peripheral-side non-facing section (44) and the surface on the inner peripheral-side non-facing section (46) has a low-friction region in which the coefficient of static friction with the facing separator is 0.4 or less.