Non-aqueous Battery Separator with Swellable Resin Layer
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Solution Overview
Problem
Current separators for non-aqueous batteries face challenges in achieving low electric resistance, high strength, and safety features such as preventing short circuits and deformation due to heat, while maintaining effective ion conductivity and mechanical integrity.
Innovation Solution
A separator comprising a base layer with a fiber aggregate and an electrolyte-swellable resin layer formed from a specific urethane resin, which is capable of swelling with liquid electrolyte, integrated to reduce resistance and ensure strength, with a heat-resistant polymer layer for thermal stability and a low melting-point polymer layer for shutdown characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a porous film made from polyolefin is used as separator, then the separator structure is simple and manufacturing is easy, but the electric resistance is high and output is limited
Solution Approach 1:
The invention uses a composite structure consisting of a polyolefin base material layer and a gel electrolyte layer. The gel electrolyte layer contains ether-based polyurethane and liquid electrolyte, creating a composite material that combines the structural advantages of polyolefin with the high ion conductivity of gel electrolyte, thereby reducing electric resistance and improving battery output while maintaining manufacturing feasibility
Solution Approach 2:
The gel electrolyte layer is designed with a porous structure that allows efficient ion transport. The pores in the gel electrolyte layer are formed through the network structure of ether-based polyurethane, enabling high ion conductivity and low electric resistance while maintaining the separator's mechanical integrity
2Reliability
If gel electrolyte is used to improve liquid retaining property, then contact between electrodes and electrolyte is improved, but the coating film layer lacks sufficient strength
Solution Approach 1:
The separator combines a polyolefin base material layer with a gel electrolyte layer containing ether-based polyurethane. The polyolefin base material provides mechanical strength and structural stability, while the gel electrolyte layer ensures good contact with electrodes and high ion conductivity, thus resolving the contradiction between strength and reliability
Solution Approach 2:
The gel electrolyte layer forms a flexible coating on the polyolefin base material, creating a thin film structure that maintains good contact with electrode surfaces while the underlying polyolefin base material provides the necessary mechanical strength and support
3Quantity of substance
If ether-based polyurethane is used in gel electrolyte, then liquid retaining property is improved, but the ability to swell with liquid electrolyte is insufficient resulting in increased internal resistance
Solution Approach 1:
The invention optimizes the composition and structure of the gel electrolyte layer by using ether-based polyurethane with specific molecular weight and crosslinking density. These parameter changes enhance both the liquid electrolyte retention capability and the swelling ability with liquid electrolyte, thereby reducing internal resistance while maintaining high liquid content
Solution Approach 2:
The gel electrolyte layer is formulated as a composite material containing ether-based polyurethane and liquid electrolyte in optimized proportions. This composite structure enables simultaneous improvement of liquid retention and electrolyte swelling capability, resolving the contradiction between quantity of liquid retained and internal resistance
4Power
If a separator with high swelling ability is used, then electric resistance is reduced, but the separator may deform under heat causing safety issues
Solution Approach 1:
The separator uses a composite structure where the polyolefin base material layer provides thermal stability and heat resistance, while the gel electrolyte layer with ether-based polyurethane provides high ion conductivity and low electric resistance. This composite design allows the separator to maintain its dimensional stability under heat while achieving low resistance
Solution Approach 2:
Different layers of the separator have different functional properties: the polyolefin base material layer is designed for thermal stability and mechanical strength, while the gel electrolyte layer is designed for high ion conductivity. This local differentiation of quality allows the separator to simultaneously achieve low electric resistance and thermal stability
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 achieves lower resistance, enhanced mechanical strength, and improved safety by preventing short circuits and deformation, while maintaining effective ion conductivity and shutdown properties.
Implementation Method 1
an electrolyte-swellable resin layer formed on at least one surface of the base layer being such that the resin layer and the base layer are integrated with each other, the resin layer being capable of swelling with liquid electrolyte
Data Source
AI summary
Provided is a separator for non-aqueous batteries, capable of being usefully used in non-aqueous batteries, and a non-aqueous battery equipped with this separator. The separator for non-aqueous batteries includes: a base layer comprising a fiber aggregate, and an electrolyte-swellable resin layer formed on at least one surface of the base layer, the resin layer comprising a urethane resin (C) obtained by reacting a polyol (A) including a vinyl polymer (a1) and a polyether polyol (a2) with a polyisocyanate (B). The vinyl polymer (a1) has as a main chain a vinyl polymer (a1') having two hydroxyl groups at one of the termini of the main chain, and a polyoxyethylene chain having a number average molecular weight of 200 to 800 as a side chain, the percentage of the polyoxyethylene chain based on the vinyl polymer (a1) being within the range of 70 mass% to 98 mass%.