Battery Separator Coating for Heat Resistance and Low Gas Generation
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Solution Overview
Problem
Existing separators for non-aqueous secondary batteries, particularly those with porous layers containing barium sulfate particles, face challenges in heat resistance and productivity, leading to gas generation and potential battery safety issues.
Innovation Solution
A separator design featuring a porous substrate with a heat-resistant porous layer containing barium sulfate particles, polyvinylidene fluoride type resin, and specific particle size and volume ratios to enhance heat resistance and suppress gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a porous layer containing barium sulfate particles is used on a porous substrate, then gas generation from electrolyte decomposition is suppressed, but heat resistance is insufficient at high temperatures
Solution Approach 1:
The patent applies composite materials by combining barium sulfate particles with heat-resistant resin (such as polyimide or polyetherimide) to form a heat-resistant porous layer. This composite structure maintains the gas suppression properties of barium sulfate while adding high-temperature stability from the heat-resistant resin matrix, resolving the contradiction between gas generation suppression and heat resistance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the porous layer by controlling the particle size distribution, porosity, and composition ratio of barium sulfate particles to heat-resistant resin. By optimizing these parameters, the layer maintains effective gas suppression at low temperatures while achieving sufficient heat resistance at elevated temperatures up to 150°C or higher.
2Temperature
If the porous layer contains barium sulfate particles with optimized properties, then heat resistance is improved, but productivity decreases
Solution Approach 1:
The patent utilizes porous materials with optimized pore structure and size distribution that allow for improved heat resistance while maintaining manufacturing efficiency. The porous structure enables effective heat management and gas suppression without requiring excessive material thickness or complex processing steps, thereby preserving productivity.
3Temperature
If a porous layer containing magnesium hydroxide or alumina is used, then heat resistance is improved, but gas generation increases due to electrolyte decomposition
Solution Approach 1:
The patent applies local quality by using barium sulfate particles specifically in the porous layer where gas generation occurs, rather than using heat-resistant materials like magnesium hydroxide or alumina throughout. This localized approach targets the gas suppression function at the electrolyte interface while maintaining overall heat resistance through the heat-resistant resin matrix, avoiding the gas generation problem associated with alternative materials.
Data Source
AI summary
An embodiment of the invention provide a separator for a non-aqueous secondary battery, including a porous substrate; and a heat-resistant porous layer that is provided on one side or on both sides of the porous substrate, and that contains a binder resin and barium sulfate particles, in which an average primary particle diameter of the barium sulfate particles contained in the heat-resistant porous layer is from 0.01 μm to less than 0.30 μm, and in which a volume ratio of the barium sulfate particles in the heat-resistant porous layer is from 30% by volume to less than 50% by volume.