Serpentine Separator Electrode Stack for Uniform Air Permeability
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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.
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 applied differently at different positions (stronger at edges, weaker at center) to compensate for natural variations in adhesive properties, achieving uniform adhesive force across all separator layers and preventing lithium precipitation
Solution Approach 2:
The patent implements local quality by applying different pressing forces to different regions of the separator sheet. The edge portions receive stronger pressing force while the central portion receives weaker force, creating a non-uniform pressing distribution that results in uniform adhesive force across the entire separator structure
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 adjusting pressing force parameters during assembly. The controlled pressing force distribution maintains consistent porosity and air permeability across all separator layers, ensuring reliable ion transport and preventing non-charging issues
Solution Approach 2:
Instead of trying to make each individual separator layer have identical air permeability, the patent inverts the approach by controlling the overall assembly to achieve uniform effective air permeability through coordinated pressing of multiple layers, where the collective structure compensates for individual variations
3Quantity of substance
If multiple electrodes are stacked with separators, then battery capacity is increased, but structural stability deteriorates due to adhesive force deviations
Solution Approach 1:
The patent maintains structural stability in multi-electrode stacks by controlling pressing force parameters during assembly. The optimized pressing force distribution ensures uniform adhesive force across all separator layers, preventing structural degradation and maintaining stability even as battery capacity increases through additional electrode layers
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, ensuring structural stability and high safety with improved adhesive force and air permeability across the electrode assembly.
Implementation Method 1
a heating unit configured to heat the separator
Implementation Method 2
a pressing unit configured to press the heated separator to be bonded to the positive electrode and the negative electrode
Data Source
Figure 1
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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 bottom electrode may have a thickness along the stacking axis that is from 80% to 120% of a thickness of the top electrode along the stacking axis. Moreover, a maximum thickness of each of the electrodes in the stack may be less than 8.3 mm.