Battery Separator Coating Layout for Electrolyte Penetration
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in achieving sufficient penetration of the electrolyte into the electrode assembly, leading to increased production costs and potential side reactions due to insufficient electrolyte penetration. Additionally, abnormal heat generation from foreign matter can cause separator deformation and voltage variations, compromising battery safety.
Innovation Solution
A separator design featuring a resin substrate with a first heat-resistant layer covering the entire first surface, a second heat-resistant layer covering part of the second surface, and a non-covered region in communication with the edge of the resin substrate. The heat-resistant layers consist of inorganic particles and a binder, with specific mass content ratios to enhance heat resistance and electrolyte penetration while minimizing deformation during abnormal heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator is thinned and electrodes are densified to increase battery capacity, then energy density is improved, but electrolyte penetration into the inner part of the electrode assembly becomes insufficient
Solution Approach 1:
The separator surface is segmented into bonding regions and non-bonding regions, creating a heterogeneous structure with voids that facilitate electrolyte penetration while maintaining structural integrity
Solution Approach 2:
Different regions of the separator are assigned different functions: bonding regions provide structural support and electrode bonding, while non-bonding regions with voids provide electrolyte penetration pathways
2Strength
If a bonding region is formed on the separator to bond the electrode and separator, then bonding strength is improved, but heat resistance and deformation suppression capability deteriorate
Solution Approach 1:
The separator is divided into bonding regions and non-bonding regions, allowing the bonding function to be localized while preserving heat-resistant properties in non-bonding regions
Solution Approach 2:
The bonding region is localized to specific areas where electrode contact is needed, while the majority of the separator maintains its original heat-resistant properties
3Reliability
If the separator deforms during abnormal heat generation, then insulation properties are compromised, but this leads to direct contact between electrodes and further heat generation
Solution Approach 1:
The separator is pre-designed with non-bonding regions that act as heat-resistant barriers, preventing deformation and maintaining insulation properties before abnormal heat generation occurs
Solution Approach 2:
The non-bonding regions, which do not bond to electrodes, are converted into beneficial heat-resistant barriers that prevent thermal runaway during abnormal conditions
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 proposed separator design achieves sufficient electrolyte penetration into the electrode assembly, reducing production costs and minimizing the risk of side reactions. It also effectively suppresses separator deformation and voltage variations during abnormal heat generation, enhancing the safety and reliability of the battery.
Implementation Method 1
the first heat-resistant layer and the second heat-resistant layer each include inorganic particles and a binder... suppresses the deformation of the separator and the variation in voltage of a battery during abnormal heat generation
Implementation Method 2
the non-covered region is in communication with an edge of the resin substrate... achieves sufficient penetration of a non-aqueous electrolyte into the inner part of the electrode assembly
Data Source
AI summary
This separator is provided with a resin substrate, a first heat-resistant layer that covers the entirety of one surface of the resin substrate, a second heat-resistant layer that covers a portion of the other surface of the resin substrate, and an uncovered region that is in the other surface of the resin substrate and that is not covered by the second heat-resistant layer, wherein the first heat-resistant layer and the second heat-resistant layer each include inorganic particles and a binder. In each of the heat-resistant layers, the contained amount of the inorganic particles is 50-90 mass %, the contained amount of the binder is 10-50 mass %, and the uncovered region is connected to the end portion of the resin substrate.