Flat Wound Cell Design for Battery Symmetry and Energy Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current secondary battery wound cells face issues with energy density reduction due to excessive separator usage and asymmetrical cell structure caused by electrode tabs, leading to potential deformation.
Innovation Solution
A flat-shaped wound cell design where separators and electrode plates are stacked and wound with electrode tabs positioned on a flat plane, reducing separator layers and optimizing tab placement to enhance symmetry and reduce material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four layers of separator are successively stacked at the innermost side of the cell, then the cell structure is complete and functional, but the separator usage is excessive and cell thickness increases, reducing energy density
Solution Approach 1:
The patent merges the functions of multiple separator layers into a single integrated separator structure. The first separator includes a first electrode plate with active material coated on both sides, while the second separator includes a second electrode plate with active material coated on one side. This combining approach reduces separator layer count from four to two, decreasing material usage and cell thickness while maintaining structural integrity and safety functions.
Solution Approach 2:
The patent makes the separator structures multi-functional by integrating electrode plates with active materials directly into the separator layers. The first separator serves both as a separator and contains a complete electrode plate with active material on both sides, while the second separator serves as both separator and contains an electrode plate with active material on one side. This multi-functionality reduces the need for separate component layers.
2Reliability
If the electrode tab is provided at the innermost side of the cell, then electrical connection is achieved, but the cell structure becomes asymmetric leading to cell deformation
Solution Approach 1:
The patent relocates the electrode tab from the innermost side (radial dimension) to the outermost side (peripheral dimension) of the wound cell. The first electrode tab is connected to the first electrode plate and extends to the outer peripheral side, while the second electrode tab is connected to the second electrode plate and also extends to the outer peripheral side. This dimensional relocation maintains electrical connection functionality while achieving symmetric cell structure.
Solution Approach 2:
The patent deliberately creates asymmetric electrode tab configurations to achieve overall cell symmetry. The first electrode tab and second electrode tab are positioned at different locations on the outer peripheral side, with their distances to respective current collector tail ends optimized (no larger than 1/3 of total length). This controlled asymmetry in tab positioning balances the overall cell structure and prevents deformation.
3Reliability
If multiple layers of separator are stacked to ensure safety and function, then cell reliability is improved, but cell thickness increases and energy density decreases
Solution Approach 1:
The patent combines separator function with electrode plate function in an integrated structure. The first separator integrates a first electrode plate with active material on both sides, and the second separator integrates a second electrode plate with active material on one side. This merging eliminates the need for separate electrode plate layers, reducing overall cell thickness while maintaining safety through the separator's inherent structure.
Solution Approach 2:
The patent creates composite separator structures that combine separator material with electrode active materials. The first separator comprises a first electrode plate with active material coated on both sides of the current collector, and the second separator comprises a second electrode plate with active material coated on one side. This composite structure achieves both separation safety and energy storage function in a single integrated component.
Data Source
AI summary
Provided is a wound cell, formed by successively stacking and winding of first separator, first electrode plate, second separator and second electrode plate from head ends thereof, the first separator is located at innermost side of the flat-shaped cell; a first and second electrode tab is electrically connected with the first and second electrode plate, respectively; the first and second electrode tabs are located on a flat plane of the flat-shaped cell along a length direction thereof and do not overlap each other in a thickness direction thereof; a distance from the first or second electrode tab to a tail end of the first or second current collector is no larger than ⅓ of total length of the first or second current collector, a sum of number of layers of the first separator and the second separator at the innermost side of the cell is no more than two.