Serpentine Separator Electrode Assembly for Uniform Adhesion and Porosity
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Solution Overview
Problem
Existing electrode assemblies experience deviations in adhesive force and air permeability across layers, leading to issues like lithium precipitation and non-charging, while maintaining adequate adhesive force and air permeability remains a challenge.
Innovation Solution
The electrode assembly employs an elongated separator sheet folded in a serpentine pattern between electrodes, with a manufacturing process involving primary and secondary heat press operations to ensure uniform adhesive force and air permeability across the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a separator sheet is used between electrodes, then adhesive force is provided to hold electrodes, but deviations in adhesive force across layers occur leading to lithium precipitation
Solution Approach 1:
The patent applies parameter changes by controlling the pressing force distribution during assembly. Specifically, the pressing force is set to be greater at the end portions of the separator sheet than at the intermediate portions, creating a non-uniform pressure distribution that compensates for natural adhesive force variations. This parameter optimization ensures uniform adhesive force across all layers, preventing lithium precipitation while maintaining adequate bonding strength.
2Reliability
If a separator sheet is used between electrodes, then air permeability is provided for ion transport, but deviations in air permeability across layers occur leading to non-charging
Solution Approach 1:
The patent controls air permeability uniformity by optimizing the pressing force parameters during assembly. The pressing force is carefully calibrated to be stronger at the end portions and weaker at the intermediate portions of the separator sheet. This parameter adjustment prevents excessive compression that would reduce air permeability, while still ensuring adequate bonding. The result is uniform air permeability across all layers, enabling reliable ion transport and preventing non-charging issues.
3Strength
If pressing force is increased to improve adhesive force, then adhesive force increases, but air permeability decreases leading to non-charging
Solution Approach 1:
The patent applies local quality by creating different pressing force conditions at different locations of the separator sheet. The end portions receive greater pressing force to ensure strong adhesive force and prevent lithium precipitation, while the intermediate portions receive lesser pressing force to maintain adequate air permeability for ion transport. This spatially differentiated pressing force distribution allows both adhesive force and air permeability to be optimized simultaneously at different locations.
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 solution prevents lithium precipitation and non-charging, ensures uniform performance, and maintains appropriate adhesive force and air permeability, enhancing the safety and efficiency of the electrode assembly.
Implementation Method 1
a heating unit that heats the separator
Implementation Method 2
a pressing unit that presses the separator and the first electrode and the second electrode to be bonded to each other
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An electrode assembly includes a plurality of electrodes arranged in a stack along a stacking axis with a respective separator portion of an elongated separator sheet positioned between and winding around each of the electrodes in the stack along a serpentine path. The plurality of electrodes include a top electrode positioned at a top of the stack along the stacking axis, and the plurality of electrodes include a bottom electrode positioned at a bottom of the stack. The separator portions in the stack include a top separator portion abutting the top electrode and a bottom separator portion abutting the bottom electrode. The top separator portion and the bottom separator portion each have a value of air permeability from 80 sec/100 ml to 120 sec/100 ml per square inch of the respective separator portion at a pressure of 0.05 MPa and at room temperature.