High Porosity Microporous Polymer Separator for Electrochemical Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium cells face inefficiencies due to low porosity in separators and electrodes, leading to restricted ion flow and suboptimal energy trade-offs, which limits battery capacity and performance.
Innovation Solution
The development of a high porosity polymer composition and centrifugal casting process to create a symmetric, strong, highly porous microporous polymer film that acts as a separator, combined with densified electrodes, ensuring unimpeded ion flow and increased battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional polymer binders and processing methods are used to fabricate electrodes, then production ease is improved, but porosity retention and ionic conductivity deteriorate
Solution Approach 1:
The patent employs highly porous polymer films with controlled pore structures (porosity >80%, sub-micron pore sizes) as separators and electrode matrices. This porous structure allows efficient ion transport while maintaining mechanical integrity, resolving the contradiction between ease of manufacture and ionic conductivity by providing a naturally porous architecture that facilitates ion flow without requiring complex processing.
Solution Approach 2:
The patent utilizes centrifugal casting process parameters (rotation speed, casting temperature, solvent evaporation rate) to control the microstructure of the polymer film. By adjusting these parameters, the process achieves >80% porosity with sub-micron pore sizes, transforming the physical and chemical properties of the polymer material to simultaneously enable easy production and high ionic conductivity.
2Quantity of substance
If electrode density is increased by calendaring, then electrode capacity is improved, but ion flow restriction worsens
Solution Approach 1:
The patent creates electrodes with non-uniform density distribution through centrifugal casting, where the pore structure and material density vary locally within the electrode. This local quality variation allows regions of high active material content for capacity while maintaining interconnected porous pathways for ion transport, resolving the contradiction between electrode capacity and ion flow.
Solution Approach 2:
The patent combines active materials with highly porous polymer matrices to create composite electrode structures. The polymer matrix provides a three-dimensional porous network that maintains ion accessibility to active material particles even at high loadings, enabling high capacity without sacrificing ion flow productivity.
3Reliability
If separator porosity is increased to eliminate ion flow bottlenecks, then ion conductivity is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent employs highly porous polymer films (>80% porosity) with controlled sub-micron pore structures as separators. The uniform porous architecture provides continuous ion transport pathways while the polymer matrix maintains mechanical integrity, achieving high ion conductivity without sacrificing mechanical strength through optimized pore formation and material selection.
Solution Approach 2:
The patent utilizes phase separation during the centrifugal casting process to create the porous structure. By controlling the phase transition of the polymer solution during solvent evaporation and cooling, a bicontinuous porous structure forms with interconnected voids for ion transport and solid polymer regions for mechanical support, resolving the strength-porosity trade-off.
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
This approach enhances ion flow and battery capacity by maintaining high porosity in the separator while achieving high density electrodes, resulting in improved electrochemical cell performance and efficiency.
Implementation Method 1
a symmetric, strong, highly porous microporous polymer film that acts as a separator, combined with densified electrodes
Data Source
AI summary
An optimized electrochemical cell comprised of a housing divided into two chambers, a first chamber containing a protogenous, ion-conducting liquid and a positive high density electrode including a first active material and a porous binder, surrounded by a surface in which the porosity level increases towards the surface, a second chamber containing an aprotic, ion conducting liquid and a negative high density electrode including a second active material and a porous binder, surrounded by a surface in which the porosity level increases towards the surface. A symmetric, strong, highly porous, microporous polymer membrane divides the housing into the first and second chamber. The porosity level of the polymer membrane is 25% greater than the porosity level at the surface of the positive and negative high density electrodes.