Battery Separator Coating Layout for Electrolyte Supply Balance
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Solution Overview
Problem
The heat-resistant layer on the separator in non-aqueous electrolyte secondary batteries, when formed only on the surface facing the positive electrode, leads to uneven electrolyte distribution, resulting in a shortage on the negative electrode side and decreased capacity during charge and discharge cycles.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a porous separator with a heat-resistant layer formed as a sheet on the surface facing the positive electrode and as dots on the surface facing the negative electrode, with the dots spaced between 30 μm and 100 μm apart, to create a sufficient space for electrolyte storage between the negative electrode and the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the heat-resistant layer is formed only on the surface facing the positive electrode, then the positive electrode side is protected from heat damage, but the electrolyte liquid becomes unevenly distributed and is in short supply on the negative electrode side
Solution Approach 1:
The patent applies different heat-resistant layer configurations to different surfaces of the separator. The first surface (positive electrode side) receives a continuous sheet-like heat-resistant layer for comprehensive protection, while the second surface (negative electrode side) receives dot-pattern heat-resistant layers that provide protection while maintaining electrolyte distribution. This local differentiation resolves the contradiction between heat protection and electrolyte supply.
Solution Approach 2:
The heat-resistant layer on the negative electrode side is segmented into discrete dots rather than a continuous sheet. This segmentation creates gaps between the dots that allow electrolyte liquid to reach the negative electrode, while the dots themselves still provide heat-resistant protection. The segmentation thus balances protection with electrolyte accessibility.
2Object-affected harmful factors
If the heat-resistant layer is formed as a continuous sheet on both surfaces, then heat protection is maximized, but electrolyte liquid storage space is reduced and capacity decreases
Solution Approach 1:
The patent differentiates the heat-resistant layer configuration between the two surfaces based on their different functional requirements. The positive electrode side requires continuous protection, so it receives a sheet-like layer. The negative electrode side requires both protection and electrolyte access, so it receives dot-pattern layers. This local quality differentiation optimizes both heat protection and electrolyte storage.
Solution Approach 2:
The dot-pattern heat-resistant layer creates a porous or discontinuous structure on the negative electrode side that allows electrolyte liquid to penetrate and be stored in the spaces between dots, while still providing heat-resistant barriers. This porous configuration balances protection with electrolyte accessibility.
3Object-affected harmful factors
If the pitch between dots is less than 30 μm, then heat protection coverage is increased, but electrolyte liquid storage space is insufficient and capacity maintenance rate decreases
Solution Approach 1:
The patent specifies an optimal pitch range (30-100 μm) for the dot-pattern heat-resistant layer that balances heat protection coverage with electrolyte storage space. This parameter optimization ensures that the dots are close enough to provide effective heat barriers but spaced far enough to allow sufficient electrolyte liquid storage and distribution to the negative electrode.
4Quantity of substance
If the pitch between dots is greater than 100 μm, then electrolyte liquid storage space is maximized, but heat protection coverage is insufficient and cycle characteristics deteriorate
Solution Approach 1:
The patent establishes an upper limit of 100 μm for the dot pitch to ensure adequate heat protection coverage. This parameter constraint ensures that the heat-resistant dots are distributed frequently enough to effectively block heat propagation while still maintaining sufficient spacing for electrolyte storage, thus preventing cycle characteristic deterioration.
Data Source
AI summary
An embodiment of the present invention provides a non-aqueous electrolyte secondary battery wherein a separator has a porous base material and a heat-resistant layer including a filler and a binding agent. The heat-resistant layer includes a first heat-resistant layer formed on a first surface of the base material facing a positive electrode and a second heat-resistant layer formed on a second surface of the base material facing a negative electrode. The first heat-resistant material is formed as a sheet on the first surface of the base material and the second heat-resistant layer is formed as dots on the second surface of the base material. The average value of the intervals between the plurality of dots constituting the second heat-resistant layer is 30-100 μm.