Serpentine Separator Electrode Assembly 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 such as lithium precipitation and non-charging, with existing manufacturing methods failing to maintain uniform performance and stability.
Innovation Solution
The electrode assembly is designed with a serpentine-folded separator structure and a manufacturing process involving primary and secondary heat press operations to ensure consistent adhesive force and air permeability, using a stack of electrodes separated by an elongated separator sheet, which is folded zigzag and thermally bonded to maintain uniformity and prevent side-effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a separator sheet is used between electrodes, then adhesive force between layers is improved, but air permeability becomes insufficient leading to lithium precipitation
Solution Approach 1:
The separator sheet is designed with a porous structure having specific porosity (30-70%) and air permeability (80-120 sec/100ml at 0.05 MPa). This porous structure allows sufficient air and electrolyte penetration while maintaining adequate adhesive force between electrode layers, preventing lithium precipitation by ensuring proper ion transport.
Solution Approach 2:
The invention optimizes specific parameters of the separator sheet including thickness (15-50 μm), porosity (30-70%), and air permeability (80-120 sec/100ml). By carefully controlling these parameters, the separator achieves a balance between adhesive strength and permeability, resolving the contradiction between holding layers together and allowing sufficient ion flow.
2Stability of the object's composition
If separator thickness is increased to improve adhesive force, then layer stability is improved, but air permeability decreases causing non-charging issues
Solution Approach 1:
The separator thickness is optimized within a specific range of 15-50 μm. This thickness provides sufficient mechanical strength and adhesive force to maintain layer stability during assembly and operation, while simultaneously maintaining adequate air permeability (80-120 sec/100ml) to ensure proper electrolyte distribution and prevent non-charging issues.
Solution Approach 2:
The porous structure of the separator with controlled porosity (30-70%) compensates for the limited thickness, providing both mechanical stability and sufficient permeability. The porous network maintains structural integrity while allowing adequate ion transport even at thinner dimensions.
3Object-affected harmful factors
If separator air permeability is increased to prevent lithium precipitation, then ion transport is improved, but adhesive force between layers decreases
Solution Approach 1:
The air permeability is optimized within the range of 80-120 sec/100ml at 0.05 MPa, and porosity is controlled at 30-70%. This parameter optimization ensures sufficient ion transport to prevent lithium precipitation while maintaining adequate adhesive force through proper material selection and structural design.
Solution Approach 2:
The porous structure provides a balance between permeability and adhesion. The pore distribution and size are controlled to allow sufficient ion flow while the solid matrix maintains mechanical strength and adhesive bonding between 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 achieves uniform performance and stability by ensuring appropriate adhesive force and air permeability, preventing lithium precipitation and non-charging, while maintaining structural integrity and efficiency.
Implementation Method 1
The top separator portion and the bottom separator portion may 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
Implementation Method 2
a primary heat press operation and a secondary heat press operation may be performed on the stack
Data Source
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.