Battery Separator Functional Layer Composition for Heat Shrinkage Resistance
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Solution Overview
Problem
Conventional non-aqueous secondary battery functional layers face challenges in achieving sufficient heat shrinkage resistance and low residual water content, which affects their high-temperature cycle characteristics.
Innovation Solution
A composition for a non-aqueous secondary battery functional layer is developed, comprising non-conductive particles with a BET specific surface area of 25 m2/g or less and a water-soluble polymer with specific monomer units, where the packing rate parameter P is set to ensure excellent heat shrinkage resistance and low residual water content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the coating film is reduced to achieve a thinner functional layer, then the thickness of the functional layer is reduced, but the heat shrinkage resistance becomes insufficient
Solution Approach 1:
The patent changes the particle size parameter of the inorganic particles to a specific range (0.03 μm to 0.1 μm) and controls the BET specific surface area (5 m²/g to 20 m²/g) to achieve optimal heat shrinkage resistance in thin functional layers. This parameter optimization allows the functional layer to maintain sufficient heat shrinkage resistance even at reduced thickness
Solution Approach 2:
The patent uses a composite composition containing inorganic particles dispersed in a specific polymer matrix (polymer with carboxyl groups). This composite structure provides both the mechanical integrity needed for thin layers and the heat shrinkage resistance required for safety, resolving the contradiction between thickness reduction and heat shrinkage performance
2Ease of manufacture
If a conventional composition for functional layer is used, then the functional layer can be formed, but the residual water content is high
Solution Approach 1:
The patent optimizes the particle size parameter (0.03 μm to 0.1 μm) and surface area parameter (BET specific surface area of 5-20 m²/g) of inorganic particles to minimize water retention while maintaining functional layer formability. The controlled particle characteristics reduce capillary water retention and improve drying efficiency
Solution Approach 2:
The patent applies local quality optimization by controlling the surface properties and size distribution of inorganic particles within the functional layer composition. This localized optimization of particle characteristics reduces water content in critical areas while maintaining overall layer integrity and ease of manufacture
3Length of moving object
If the thickness of the coating film is reduced, then the functional layer is thinner, but the high-temperature cycle characteristics deteriorate
Solution Approach 1:
The patent optimizes the particle size (0.03 μm to 0.1 μm) and surface area (BET specific surface area of 5-20 m²/g) parameters to achieve a balance where thin functional layers maintain sufficient mechanical strength and thermal stability for good high-temperature cycle characteristics
Solution Approach 2:
The composite composition of inorganic particles in a polymer matrix provides enhanced thermal stability and mechanical properties that enable thin functional layers to withstand high-temperature cycling without deteriorating performance
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 effectively forms a functional layer with enhanced heat shrinkage resistance and reduced residual water content, leading to improved high-temperature cycle characteristics for non-aqueous secondary batteries.
Implementation Method 1
a composition for a non-aqueous secondary battery functional layer, a functional layer for a non-aqueous secondary battery, a separator for a non-aqueous secondary battery, and a non-aqueous secondary battery
Implementation Method 2
a functional layer composed of a porous membrane layer formed by binding non-conductive particles using a binder (binding material)
Implementation Method 3
applying a composition for a functional layer that contains non-conductive particles, various polymers that can function as binders, and a dispersion medium onto the surface of a substrate (separator substrate, electrode substrate, etc.), and then drying the applied composition for a functional layer
Data Source
AI summary
Provided is a composition for a non-aqueous secondary battery functional layer containing non-conductive particles, a water-soluble polymer, and water, wherein the non-conductive particles have a BET specific surface area of 25 m2/g or less, and the following parameter P is 35 or more. Parameter P=packing rate of composition for non-aqueous secondary battery functional layer/Log(BET specific surface area of non-conductive particles), given that: packing rate of composition for non-aqueous secondary battery functional layer (%)={(solid content in composition for non-aqueous secondary battery functional layer (volume %)×volume of composition for non-aqueous secondary battery functional layer in test tube)/volume of sediment layer}×100%.