Secondary Battery Positive Electrode with Thin Region for Deformation Relief
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Solution Overview
Problem
The plastic deformation of electrode plates in secondary batteries, such as lithium-ion batteries, during charge and discharge leads to potential short circuits, necessitating complex insulation measures that increase cost and reduce capacity.
Innovation Solution
A positive electrode design with a first region and a second region of reduced thickness, positioned on the winding core side, effectively inhibits plastic deformation by allowing stress relaxation and minimizing expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation measures are taken to prevent short circuit caused by plastic deformation, then reliability is improved, but device complexity increases
Solution Approach 1:
The electrode plate structure is modified locally by creating a reduced thickness region at the specific position where plastic deformation occurs during winding. This local structural change provides stress relaxation capability exactly where needed, preventing short circuit between electrodes without requiring insulation measures throughout the entire electrode assembly.
2Reliability
If insulation measures are disposed between electrode assembly and exterior housing, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of applying insulation measures across the entire electrode assembly, the invention creates a localized reduced thickness region at the winding core side. This local modification prevents plastic deformation at the critical location where electrodes may contact the exterior housing, eliminating the need for additional insulation components and simplifying manufacturing.
3Strength
If electrode plate is made thicker to prevent deformation, then strength is improved, but volume increases
Solution Approach 1:
The invention applies thickness modification only at the specific location where plastic deformation occurs (the winding core side), rather than uniformly increasing or decreasing the thickness of the entire electrode plate. This localized approach maintains structural strength where needed while minimizing overall volume increase.
Solution Approach 2:
The electrode plate thickness is segmented into different regions: a reduced thickness region at the winding core side for stress relaxation, and a normal thickness region elsewhere for maintaining structural strength. This segmentation allows the electrode to achieve both deformation resistance and compact volume.
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
The design significantly reduces plastic deformation of both positive and negative electrodes, simplifies insulation requirements, and maintains high capacity and efficiency.
Implementation Method 1
the second region is provided from one end in a length direction of the positive electrode mixture layer with a length of greater than or equal to 8% of a length of the positive electrode mixture layer
Data Source
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AI summary
A positive electrode (11), which is an example of an embodiment, comprises: a long positive electrode core body (30); and a positive electrode mixture layer (31) disposed on both surfaces of the positive electrode core body (30). The positive electrode mixture layer (31) includes a first region (32) and a thin portion (33) that is a second region thinner than the first region (32). The thickness of the thin portion (33) is 20-98% of the average thickness of the first region (32). The thin portion (33) is provided at a length of 8% or more of the length of the positive electrode mixture layer (31) from a starting end (11x), which is one end in the length direction of the positive electrode mixture layer (31).