Wound Electrode Assembly Cushioning for Tab Lead Pressure Relief
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Solution Overview
Problem
The existing power storage cells with wound electrode assemblies face issues of local pressure due to unevenness caused by the thickness of tab leads, which can lead to mechanical stress and potential performance degradation.
Innovation Solution
Incorporating a cushioning material with a lower elastic modulus than the tab lead and current collector, disposed adjacent to the tab lead on uncoated portions of the current collector, to reduce unevenness and prevent local pressure application during the winding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tab lead with significant thickness is used for electrical connection, then the electrical conductivity and current carrying capacity are improved, but unevenness is formed on the current collector surface causing local pressure on the wound electrode assembly
Solution Approach 1:
The patent applies local quality by providing cushioning material only at specific locations where tab leads are disposed on the current collector, rather than uniformly across the entire surface. This localized approach compensates for thickness variations only where needed, maintaining surface uniformity while preserving the electrical connection functionality of the tab leads.
Solution Approach 2:
The cushioning material is placed in advance on the current collector at positions where tab leads will be attached. This beforehand cushioning prevents the formation of unevenness before the tab leads are installed, thereby avoiding local pressure issues in the final wound electrode assembly while maintaining reliable electrical connections.
2Volume of moving object
If the wound electrode assembly is tightly confined in a case to improve energy density, then the volume efficiency is improved, but local pressure from unevenness causes mechanical stress and potential performance degradation
Solution Approach 1:
By placing cushioning material on the current collector before assembling the electrode and confining it in the case, the patent prevents unevenness from forming. This allows the electrode assembly to be tightly confined for high energy density while avoiding the mechanical stress and performance degradation that would result from local pressure on protruding tab leads.
Solution Approach 2:
The cushioning material is strategically placed only at locations where tab leads create unevenness, allowing tight confinement of the overall assembly for high energy density while locally compensating for thickness variations to maintain mechanical integrity.
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 use of cushioning material effectively minimizes unevenness and reduces the likelihood of local pressure on the wound electrode assembly, enhancing the structural integrity and performance of the power storage cell by allowing for more even deformation and adhesion during winding.
Implementation Method 1
the cushioning has a lower elastic modulus than the tab lead. When the first electrode is unfurled in a form of sheet, a thickness of the cushioning in an orthogonal direction orthogonal to the current collector is greater than or equal to a thickness of the tab lead in the orthogonal direction. Since the cushioning has a lower elastic modulus than the tab lead, the cushioning is more likely to deform than the tab lead.
Data Source
AI summary
A power storage cell includes a wound electrode assembly which includes a positive plate (a first electrode), a negative plate (a second electrode), and a separator. The positive plate includes a positive current collector (a current collector), a positive electrode mixture layer (an electrode material layer) with which a portion of the positive current collector is coated, a positive tab lead (a tab lead), and an adhesive (a cushioning). The positive tab lead is disposed on an uncoated portion that is not coated with the positive electrode mixture layer. The adhesive is disposed adjacent to the positive tab lead on the uncoated portion.