Annular Polymer Separator for Lithium Battery Adhesion
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Solution Overview
Problem
Conventional rechargeable lithium battery separators face challenges in maintaining optimal ion conductivity and adherence to electrodes, leading to issues such as clogging, reduced cycle-life characteristics, and increased interfacial resistance due to uneven polymer coating and potential side reactions with the electrolyte.
Innovation Solution
A separator with a porous substrate coated with annular patterns of polyvinylidene fluoride-based and (meth)acryl-based polymer microparticles, specifically designed to minimize clogging and enhance ion conductivity, featuring a controlled particle diameter, ring width, and loading amount, which improves adhesion and reduces interfacial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coating layer is applied on the porous substrate to improve adhesion, then adherence to electrodes is improved, but ion conductivity deteriorates due to clogging of pores
Solution Approach 1:
The coating layer is segmented into discrete annular patterns rather than a continuous coating. This segmentation allows polymer microparticles to be distributed in isolated rings, providing adhesion points while leaving gaps between rings that maintain pore openness for ion transport.
Solution Approach 2:
The annular patterns create local regions of high polymer concentration at the ring structures for enhanced adhesion, while the centers and inter-ring regions maintain low polymer concentration to preserve ion conductivity. This local quality variation resolves the contradiction between needing adhesion and maintaining ion transport.
2Strength
If polymer coating amount is increased to improve adhesion, then adherence to electrodes is improved, but cycle-life characteristics deteriorate due to side reactions with electrolyte
Solution Approach 1:
Instead of applying excessive polymer coating throughout the entire separator surface, the invention applies polymer microparticles in partial coverage annular patterns. This provides sufficient adhesion through concentrated ring structures while minimizing total polymer-electrolyte contact area, reducing side reactions and improving cycle life.
3Strength
If polymer microparticles are uniformly distributed to improve adhesion, then adherence to electrodes is improved, but interfacial resistance increases due to uneven coating
Solution Approach 1:
The spray coating method with controlled parameters (pressure, pulse duration, temperature) prepares the coating layer in advance with uniform annular patterns before battery assembly. This preliminary controlled deposition ensures consistent microparticle distribution and ring formation, preventing uneven coating and reducing interfacial resistance.
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 enhances ion conductivity, adherence, and cycle-life characteristics of rechargeable lithium batteries by optimizing the distribution and amount of polymer microparticles on the separator, thereby improving battery performance and stability.
Implementation Method 1
a coating layer including a plurality of annular patterns on at least one surface of the porous substrate... improves adhesion and reduces interfacial resistance
Implementation Method 2
a porous substrate... may provide a movement path of ions in the electrolyte while preventing direct contact (and thus an internal short-circuit) between the positive electrode and the negative electrode
Implementation Method 3
coating the coating layer composition on at least one surface of the porous substrate by a spray coating method
Data Source
AI summary
A separator for a rechargeable battery includes a porous substrate, and a coating layer including a plurality of annular patterns on at least one surface of the porous substrate. The annular patterns may include a plurality of polymer microparticles, the annular patterns may have an average particle diameter (D50) of about 50 μm to about 500 μm, and rings of the annular patterns may have a ring width of about 5 μm to about 50 μm.